Sewing machine frame having reinforced structure and sewing machine provided with the frame

Information

  • Patent Grant
  • 6796255
  • Patent Number
    6,796,255
  • Date Filed
    Friday, September 27, 2002
    22 years ago
  • Date Issued
    Tuesday, September 28, 2004
    20 years ago
Abstract
A sewing machine frame having reinforced structure for use in a sewing machine is disclosed. The sewing machine frame has a frame member formed of a synthetic resin and having a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion at a position above the bed portion, the bed portion, the tower portion and the arm portion being formed integrally and providing a concaved peripheral wall defining a stitch working space. The sewing machine frame is characterized by a peripheral wall reinforcing rib protruding from the frame member, the peripheral wall reinforcing rib extending along the peripheral wall and ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a sewing machine frame made from a synthetic resin in which an arm portion, a tower portion and a bed portion are provided integrally. The present invention also relates to a sewing machine having the sewing machine frame.




In the sewing machine frame, a horizontally extending arm portion supports a reciprocation mechanism for a needle carrying a needle thread, and the tower portion vertically extends from the bed portion for supporting the arm portion in a cantilevered fashion. In the bed portion, a loop taker is supported for trapping a loop of the needle thread carried on the vertically reciprocating needle in order to form a stitch.




In the sewing machine, a smooth stitching operation is required. To this effect, vibration and displacement of a needle tip due to the vertically reciprocating motion of the needle must be reduced or minimized, otherwise a loop seizing beak of the loop taker disposed in the bed portion cannot trap the needle thread loop formed by vertical reciprocation of the sewing needle. Thus, the stitching may be degraded.




In order to avoid this problem, the needle & rotary hook timing must be adequately provided. To this effect, the sewing machine frame must provide high rigidity capable of avoiding deformation or displacement thereof due to reaction force occurring when the needle penetrates a workpiece fabric. Therefore, in the conventional sewing machine, a metallic frame having high rigidity is provided in an interior of a sewing machine cover, and a stitch forming mechanism including a needle vertical reciprocating mechanism and the loop taker is attached to the metallic frame.




However, such a conventional arrangement is costly, bulky and heavy. More specifically, the sewing machine frame has a rigid box shape arrangement in order to provide high rigidity. Further, the frame is made from a metal such as a cast iron or aluminum, which in turn increase weight and size. Further, high skill and elaboration is required for assembling the sewing machine because the stitch forming mechanism must be installed into the metallic frame through a small area opening thereof. This increases assembly cost.




Laid open Japanese Patent Application Kokai No. Hei-11-137880 discloses a sewing machine frame made from a synthetic resin to reduce production cost and to provide a light weight frame. As shown in

FIG. 16

, the frame


300


has an open end arrangement in a U-shape cross-section in which a bed portion


304


, a tower portion


303


and an arm portion


302


are provided integrally, and a reinforcing plate


301


is fixed between upper and lower portions at the open end of the bed portion


304


.




However, the disclosed sewing machine frame


300


provides a rigidity still lesser than that of the metallic frame. More specifically, as shown in

FIG. 16

, vertical vibration occurs in the arm portion


302


due to a load exerted along a vertical line containing the needle, the load being caused by the reciprocating motion of the needle during stitching operation. Further, a horizontal swing also occurs at an upper portion of the tower portion


303


during stitching.




Such vibration and swing occur due to the cantilevered support structure of the arm portion


302


with respect to the tower


303


. That is, a combination of the arm portion


303


, the tower portion


303


and the bed portion


304


provides an arcuate recessed wall


305


, and a stress generated by the vertically reciprocating motion of the needle will be concentrated on the wall


305


. However, the wall


305


does not have a sufficient rigidity, and therefore, such unwanted vibration and swing occur to lower stitching quality in comparison with the conventional sewing machine provided with the metallic frame.




SUMMARY OF THE INVENTION




It is an object of the present invention to overcome the above-described problems and to provide a sewing machine frame having a bed portion, a tower portion and an arm portion those integrally with each other and formed of a synthetic resin, yet having high rigidity, and to provide a sewing machine having such an improved sewing machine frame.




This and other objects of the present invention will be attained by a sewing machine frame for use in a sewing machine including a frame member, and a peripheral wall reinforcing rib. The frame member is formed of a synthetic resin and has a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion at a position above the bed portion. The bed portion, the tower portion and the arm portion are formed integrally and provide a concaved peripheral wall defining a stitch working space. The peripheral wall reinforcing rib protrudes from the frame member. The peripheral wall reinforcing rib extends along the peripheral wall and ranges at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.




In another aspect of the invention, there is provided a sewing machine frame for use in a sewing machine including an outer panel wall, a side wall, a peripheral wall reinforcing rib, and an outer panel wall reinforcing rib. The outer panel wall constitutes a front wall and a rear wall and has a peripheral edge. The side wall protrudes from the peripheral edge to provide a closed space with the outer panel wall and is formed integrally with the outer panel wall with a synthetic resin. A combination of the outer panel wall and the side wall provides a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion and positioned above the bed portion. The side wall has a part providing a concaved peripheral wall which defines a stitch working space surrounded by the bed portion, the tower portion and the arm portion. The peripheral wall reinforcing rib protrudes from the outer panel wall and extends along the peripheral wall. The peripheral wall reinforcing rib ranges at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion. The outer panel wall reinforcing rib protrudes from the outer panel wall for reinforcing the same.




In still another aspect of the invention, there is provided a sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, a stitch forming mechanism of the sewing machine being assembled in the sewing machine frame. The sewing machine frame includes an integral main frame body, an integral frame cover and a concave wall reinforcing rib. The integral main frame body is made from a synthetic resin and to which the stitch forming mechanism is assembled. The integral main frame body includes a back panel wall having a first peripheral edge, and a first side wall integrally protruding from the first peripheral edge. The integral main frame body provides an arm section, a tower section and a bed section. The integral frame cover is made from a synthetic resin and is attached to the main frame body. The integral frame cover includes a front panel wall having a second peripheral edge, and a second side wall integrally protruding from the second peripheral edge for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the bed section, and a complementary arm section to form the arm portion with the arm section. The first side wall and the second side wall have parts defining a concave wall surroundingly provided by the combination of the arm portion, the tower portion, and the bed portion. The concave wall reinforcing rib extends along the concave wall and ranges at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.




In still another aspect of the invention, there is provided a sewing machine frame for use in a sewing machine including an outer panel wall, a side wall, and a reinforcing member. The outer panel wall constitutes a front wall and a rear wall. The side wall protrudes from a peripheral edge of the outer panel wall to provide a closed space with the outer panel wall and is formed integrally with the outer panel wall with a synthetic resin. A combination of the outer panel wall and the side wall provides a bed portion extending in its longitudinal direction, a tower portion upstanding from the bed portion, and an arm portion extending in its longitudinal direction from the tower portion and positioned above the bed portion. A congregated area among the bed portion, the tower portion and the arm portion provides a concaved peripheral wall defining a stitch working space of the sewing machine. The reinforcing member is formed integrally with the outer panel wall and has a generally semi-circular hollow cross-section. The reinforcing member is positioned along the peripheral wall and has one end portion positioned in the arm portion and extending in the longitudinal direction thereof, and has another end portion positioned in the bed portion and extending in the longitudinal direction thereof.




In still another aspect of the invention, there is provided a sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, a stitch forming mechanism of a sewing machine being assembled in the sewing machine frame. The sewing machine frame includes an integral main frame body, an integral frame cover, and a reinforcing member. The integral main frame body is made from a synthetic resin and to which the stitch forming mechanism is assembled. The integral main frame body includes a back panel wall having a peripheral edge, and a side wall integrally protruding from the peripheral edge. The integral main frame body provides an arm section, a tower section and a bed section. The side wall has a part defining a peripheral wall surroundingly provided by the combination of the arm section, the tower section and the bed section. The integral frame cover serves as a front panel wall and is made from a synthetic resin and is attached to the main frame body for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the tower section, and a complementary arm section to form the arm portion with the arm section. The reinforcing member is formed integrally with the main frame body and has a generally semi-circular hollow cross-section. The reinforcing member is positioned along the peripheral wall and has one end portion positioned in the arm section and extending in the longitudinal direction thereof, and has another end portion positioned in the bed section and extending in the longitudinal direction thereof.




In still another aspect of the invention, there is provided a sewing machine including a stitch forming mechanism and any one of the above-described sewing machine frames.











BRIEF DESCRIPTION OF THE DRAWINGS




The aforementioned aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawing figures wherein:





FIG. 1

is a front view showing the overall construction of a sewing machine comprising a frame according to the preferred embodiment;





FIG. 2

is a side view showing the overall construction of the sewing machine in

FIG. 1

;





FIG. 3

is a perspective view showing the external appearance of a main frame;





FIG. 4

is a perspective view showing the internal construction of the main frame;





FIG. 5

is a plan view showing the internal construction of the main frame;




FIG.


6


(A) is a cross-sectional view along the plane of the main frame indicated by the arrows A in

FIG. 5

;




FIG.


6


(B) is a cross-sectional view along the plane of the main frame indicated by the arrows B in

FIG. 5

;




FIG.


7


(A) is a cross-sectional view along the plane of the main frame indicated by the arrows C in

FIG. 5

;




FIG.


7


(B) is an enlarged view showing the lower end of the main frame;




FIG.


7


(C) is a cross-sectional view along the plane of the main frame indicated by the arrows D in

FIG. 5

;




FIG.


8


(A) is a cross-sectional view along the plane of the main frame indicated by the arrows E in

FIG. 5

;




FIG.


8


(B) is a cross-sectional view along the plane of the main frame indicated by the arrows F in

FIG. 5

;




FIG.


8


(C) is an enlarge view of a protrusion;




FIG.


8


(D) is a cross-sectional view along the plane of the main frame indicated by the arrows M in

FIG. 5

;




FIG.


9


(A) is an enlarged plan view showing the main frame from the perspective of the line G in

FIG. 5

;




FIG.


9


(B) is an enlarged plan view showing the main frame from the perspective of the line H in

FIG. 5

;





FIG. 10

is a perspective view showing the external appearance of the frame cover;





FIG. 11

is a perspective view showing the internal construction of the frame cover;





FIG. 12

is a plan view showing the internal construction of the frame cover;





FIG. 13

is a cross-sectional view along the plane of the frame cover indicated by the arrows I in

FIG. 12

;




FIG.


14


(A) is a cross-sectional view along the plane of the frame cover indicated by the arrows J in

FIG. 12

;




FIG.


14


(B) is an enlarged view showing the lower end of the frame cover;




FIG.


15


(A) is an enlarged plan view along the plane of the frame cover indicated by the arrows K in

FIG. 12

;




FIG.


15


(B) is an enlarged plan view along the plane of the frame cover indicated by the arrows L in

FIG. 12

; and





FIG. 16

is a perspective view showing a conventional sewing machine frame.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Structure of a Sewing Machine




A sewing machine frame according to a preferred embodiment of the present invention will be described while referring to the accompanying drawings. First the overall construction of a sewing machine comprising a frame according to the preferred embodiment will be described with reference to

FIGS. 1 and 2

.

FIG. 1

is a front view, and

FIG. 2

is a side view showing the overall construction of the sewing machine comprising a frame


1


according to the preferred embodiment.




As shown in

FIG. 1

, the frame


1


substantially comprises a bed


8


, a cantilever support


7


provided vertically on the bed


8


, an arm


6


, and an arm


6


cantilevered from the cantilever support


7


above the bed


8


. The bed


8


, the cantilever support


7


, and the arm


6


are integrally formed of a synthetic resin in a substantially C shape.




The frame


1


supports a stitch forming mechanism including a loop taker and a mechanism for driving a needle


16


reciprocally up and down, and constitutes a shell of the sewing machine. In other words, the frame


1


does not need any metallic frame for mounting the stitch forming mechanism. Accordingly, it is possible to manufacture a lighter frame


1


having simplified structure, compared with a conventional metal frame to mount a stitch forming mechanism, covering with a resin cover. The frame


1


may be formed of a synthetic resin material by using a well-known injection molding method.




The synthetic resin material for the frame


1


may be a noncrystalline thermoplastic resin, such as a styrene resin. More specifically, the material may be one or mixture of acrylonitrile-butadiene-styrene copolymer, polystyrene, acrylonitrile-styrene, acrylonitrile-acrylate-styrene, acrylonitrile-ethylene-styrene, chlorinated acrylonitrile-polyethylene-styrene. Of these materials, a resinous matter having acrylonitrile-butadiene-styrene copolymer as the primary component with an inorganic additive of talc or glass bead has good rigidity and a good thermal expansion coefficient. The usage of the above material may eliminate frame coating in the later step due to a good appearance of the frame.




The arm


6


supports a top mechanism


3


for reciprocally driving the needle


16


up and down, the needle


16


retaining needle thread. A motor


2


provided in the cantilever support


7


generates rotational motion. The top mechanism


3


converts this rotational motion to reciprocal motion by means of a crank mechanism to transfer the reciprocal motion to the needle


16


. The top mechanism


3


comprises a spindle


12


, a thread take-up crank


13


, a needle bar holder


14


, a needle bar


15


, and a thread take-up lever link hinge pin


17


mounted in a metal top frame


11


. The top frame


11


is directly attached to the frame


1


by several screws.




Next, the operations of the top mechanism


3


will be described. A rotational driving force generated by the motor


2


is transferred to a large pulley


35


via a motor belt


36


. The rotational driving force transferred to the large pulley


35


is further transferred to the thread take-up crank


13


via an arm shaft


31


and the spindle


12


. The arm shaft


31


is rotatably supported by two bearings


32


,


32


. The spindle


12


is linked to the arm shaft


31


via a coupler. Through the movement of a needle bar crank rod, rotational motion transferred to the thread take-up crank


13


is converted to reciprocal motion of the needle bar


15


that is supported rotatably on the needle bar holder


14


. The needle bar


15


is capable of moving vertically in the needle bar holder


14


. This reciprocal motion is transferred to the needle


16


.




The arm


6


is supported on the top end of the cantilever support


7


, while the bed


8


is connected to the bottom end of the cantilever support


7


. A drive transferring mechanism


5


is disposed in the cantilever support


7


for transferring rotational driving force generated by the motor


2


to the top mechanism


3


housed in the arm


6


and a lower mechanism


4


housed in the bed


8


. The drive transferring mechanism


5


comprises the motor


2


, the large pulley


35


, the motor belt


36


, a pulley


38


, a pulley


39


, and a timing belt. The drive transferring mechanism


5


is directly attached to the frame


1


. The motor


2


is supported by motor supporting brackets


33


that are fixed near the bottom end of the cantilever support


7


.




Next, the operations of the drive transferring mechanism


5


will be described. The rotational driving force provided by the motor


2


is transferred to the large pulley


35


via the motor belt


36


. The rotational driving force transferred to the large pulley


35


is then transferred to the arm shaft


31


rotatably supported by the two bearings


32


,


32


. As described above, this rotational motion is transferred to the top mechanism


3


via the spindle


12


, while this movement is also transferred to the lower mechanism


4


. That is, the pulley


39


is fixed at approximately the center point of the arm shaft


31


. Rotational motion transferred to the pulley


39


is further transferred to the pulley


38


disposed in the bed


8


via the timing belt


41


. A rotary hook shaft


37


is rotatably supported by a bearing


32


. Since the rotary hook shaft


37


is linked to the pulley


38


, the rotary hook shaft


37


rotates in synchronization with the rotations of the arm shaft


31


due to the rotational motion of the pulley


38


.




The cantilever support


7


is formed on one end of the bed


8


. The bed


8


supports a rotary hook


23


constituting a loop taker for catching a thread loop of the needle thread as the needle moves up and down and forming a stitch. The lower mechanism


4


is provided inside the bed


8


for rotating the rotary hook


23


in synchonization with the reciprocal motion of the needle


16


. The lower mechanism


4


comprises a rotary hook shaft


21


, a helical gear


22


, the rotary hook


23


, a helical gear


24


, and the rotary hook shaft


37


mounted on a metal lower frame


20


. The lower frame


20


is mounted directly on the frame


1


by a plurality of screws.




Next, the operations of the lower mechanism


4


will be described. The rotational motion transferred via the timing belt


41


to the pulley


38


is transferred to the helical gear


22


via the rotary hook shaft


37


rotatably supported by the bearing


32


and the rotary hook shaft


21


rotatably supported by two bearings


25


,


25


and linked to the rotary hook shaft


37


via a coupler. As shown in

FIG. 2

, the helical gear


22


is fixed on the rotary hook shaft


21


. A rotary hook shaft on which the rotary hook


23


is fixed is rotatably supported on the lower frame


20


for rotating beneath the top surface of the bed


8


. The helical gear


24


engaged with the helical gear


22


is fixed to the rotary hook shaft. Accordingly, when the rotary hook shaft


21


rotates, the rotary hook


23


rotates via the helical gear


22


and helical gear


24


. At the same time, A loop seizing beak of the loop taker moves in synchronization with the tip of the needle


16


, and catches the thread loop of the needle thread supported on the needle


16


as the needle


16


moves vertically.




Sewing Machine Frame




In order to execute smooth sewing operations with a sewing machine having the construction described above, it is necessary to minimize vibration caused by the vertical movement of the needle


16


. Simultaneously, displacement of the needle tip caused by deformation of the frame


1


due to the vertical movement of the needle


16


is required to be minimized. This is because large amount of the displacement and the vibration of the needle tip can prevent the loop seizing beak of the loop taker provided in the bed


8


from catching the thread loop, resulting in the formation of an inappropriate stitch. To avoid this, it is necessary to maintain at all times an appropriate needle and rotary hook timing between the loop seizing beak of the rotating rotary hook


23


and the needle


16


that is moved reciprocally up and down. Accordingly, the frame


1


must have high rigidity in order to prevent deformation (displacement) due to a reaction force generated when the needle penetrates a working piece cloth. However, since it is difficult to maintain sufficient rigidity in a frame formed of synthetic resin, the frame


1


of the present embodiment employs various constructions to achieve sufficient rigidity.




As shown in

FIG. 2

, the frame


1


is formed of a main frame


1


A and a frame cover


1


B along a dividing plane


52


formed in approximately the center of the periphery of the frame


1


when viewed from the end (the dotted line in FIG.


2


). The main frame


1


A is provided with the stitch forming mechanism including the top mechanism


3


for driving the needle


16


reciprocally up and down and the lower mechanism


4


for rotating the rotary hook


23


is mounted. The frame cover


1


B is coupled to the main frame


1


A to cover the stitch forming mechanism.




The insides of the main frame


1


A and frame cover


1


B are configured to accommodate the top mechanism


3


and the lower mechanism, as shown when the main frame


1


A and frame cover


1


B are in an open state divided along the dividing plane


52


(refer to FIGS.


4


and


11


). When assembling the sewing machine, the top mechanism


3


and the lower mechanism are first mounted in the main frame


1


A while the main frame


1


A is rendered in an open state. The main frame


1


A and frame cover


1


B are then joined together by inserting screws through couplings


90


,


190


provided in the main frame


1


A and the frame cover


1


B (see FIGS.


4


and


11


). By simplifying the process for assembling the sewing machine in this way, it is possible to reduce the assembly costs. Since the open area of the frame is closed after assembly, the frame retains sufficient rigidity, and the arm


2


is not easily subject to torsional deformation due to reciprocal motion of the needle


16


.




Main Frame




Next, the main frame


1


A of the frame


1


will be described with reference to

FIGS. 3 through 9

.

FIG. 3

is a perspective view showing the external appearance of the main frame


1


A.

FIG. 4

is a perspective view showing the internal construction of the main frame


1


A.

FIG. 5

is a plan view showing the internal construction of the main frame


1


A. FIG.


6


(A) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows A in FIG.


5


. FIG.


6


(B) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows B in FIG.


5


. FIG.


7


(A) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows C in FIG.


5


. FIG.


7


(B) is an enlarged view showing the lower end of the main frame


1


A. FIG.


7


(C) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows D in FIG.


5


. FIG.


8


(A) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows E in FIG.


5


. FIG.


8


(B) is a cross-sectional view along the plane of the main frame


1


A indicated by the arrows F in FIG.


5


. FIG.


8


(C) is an enlarge view of a protrusion shown in FIG.


8


(B). FIG.


8


(D) is a cross sectional view along the plane of the main frame


1


A indicated by the arrows M. FIG.


9


(A) is an enlarged plan view showing the main frame


1


A from the perspective of the line G in FIG.


5


. FIG.


9


(B) is an enlarged plan view showing the main frame


1


A from the perspective of the line H in FIG.


5


.




As shown in

FIG. 3

, the main frame


1


A substantially comprises the arm


6


, the cantilever support


7


, and the bed


8


formed integrally. The semicircular space surrounded by the arm


6


, cantilever support


7


, and bed


8


is a space


9


.




In addition, the main frame


1


A comprises a back panel wall


250


constituting a back side of the sewing machine, and side wall


251


extending from a peripheral edge


250




a


of the back panel wall


250


. Especially, the surface of the main frame


1


A facing the space


9


is designated as an inner surface wall


51


. The inner surface wall


51


has a rectangular opening


53


that a cloth-pressing lever for fabric (not shown) is passed through.




As shown in

FIGS. 1

,


4


and


5


, the main frame


1


A is provided with an arrangement for mounting stitch forming mechanism. More specifically, the interior of the arm


6


is provided with a pair of thread take-up shaft supports


140


,


140


for rotatably supporting the thread take-up lever link hinge pin (not shown); a needle bar holder mount


141


on which the needle bar holder


14


is mounted; an upper frame mount


142


on which the top frame


11


is mounted; and a pair of arm shaft supports


144


,


144


for rotatably supporting the arm shaft


31


that transfers the rotational drive force from the motor


2


to the top mechanism


3


. Motor support bracket mounts


146


are mounted in the cantilever support


7


for attaching the motor supporting brackets


33


that fixedly support the motor


2


. Further, the interior of the bed


8


is provided with a pair of lower conducting shaft supports


147


,


147


for rotatably supporting the rotary hook shaft


37


that transfer the rotational drive force from the motor


2


to the lower mechanism


4


, and a lower frame mount


148


on which the lower frame


20


is mounted.




Reinforcing Member




Referring to

FIGS. 4 and 5

, a reinforcing member


60


is provided around the inner surface wall


51


of the main frame


1


A facing the space


9


surrounded the arm


6


, cantilever support


7


, and bed


8


. The reinforcing member


60


is formed integrally with the back panel wall


250


. One end of the reinforcing member


60


extends along the longitudinal direction of the arm


6


to the point adjacent to the side wall


251


at one end of the arm


6


opposing the cantilever support


7


. The other end of the reinforcing member


60


extends along the longitudinal direction of the bed


8


to the point adjacent to the side wall


251


at one end of the bed


8


opposing the bed


8


. As described above, the reinforcing member


60


comprises three parts: one part placed around the inner surface wall


51


in a semicircle shape, another part placed in a linear manner as if it crosses the arm


6


, and the other part placed in a linear manner as if it crosses the bed


8


. Accordingly, the reinforcing member


60


is placed in a continuous manner to form a U-shape as a whole. The above structure of the reinforcing member


60


reinforces projecting portions of the arm


6


and the bed


8


which extend from the cantilever support


7


.




Referring to FIG.


8


(D), the reinforcing member


60


has a tubular shape with a hollow circular cross-section. This reinforcing member


60


is formed with the back panel wall


250


integrally to project from the inner surface of the back panel wall


250


. The reinforcing member


60


is formed in a tubular shape for the following reasons. As described above, the main frame


1


A is formed according to an injection molding method. In this method, after injecting a molten resinous material in a cavity die shell, the resinous material is cooled. At this time, thicker portions of the molded product harden slower than thinner portions. Since contraction is greater at the thicker portions, shrinkage occurs in those portions. In order to prevent such shrinkage, it is necessary to maintain a uniform thickness in the molded product. For this reason, the reinforcing member


60


is formed in a hollow tubular shape. When forming the frame


1


, the tubular shape of the reinforcing member


60


is formed by injecting an inert fluid, such as argon gas or nitrogen gas, through an injection hole


61


formed at one end of the reinforcing member


60


adjacent to the side wall


251


, and subsequently cooling the reinforcing member


60


.




The above structure of the reinforcing member


60


ensures the rigidity of the inner surface wall


51


facing the space


9


surrounded by the arm


6


, the cantilever support


7


, and the bed


8


on which stress caused by the reciprocating motion of the needle


16


is concentrated. The above structure of the reinforcing member


60


also ensures the rigidity of the back panel wall


250


and the side wall


251


of the arm


6


, cantilever support


7


, and bed


8


adjacent to the inner surface wall


51


. Accordingly, a sewing machine including the main frame


1


A prevents horizontal and vertical vibrations of the main frame


1


A caused by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




In addition, the reinforcing member


60


has a semicircle hollow section to achieve a light weight and provide sufficient rigidity. The reinforcing member


60


is formed integrally with the back panel wall


250


. Accordingly, process for manufacturing the main frame


1


A is simplified.




In the embodiment described above, the reinforcing member


60


has one end extending to the point adjacent to the side wall


251


placed at the tip of the arm


6


, and the other end extending to the point adjacent to the side wall


251


placed at the tip of the bed


8


. In another embodiment, the reinforcing member


60


may extend to a certain point between the arm


6


and the bed


8


. It is preferable that the reinforcing member


60


is provided around at least the space


9


. In this case, the arrangement of the reinforcing member


60


may have a J-shape, C-shape, or a rectangular shape with one open side.




Auxiliary Reinforcing Member




Referring to

FIGS. 4 and 5

, the back panel wall


250


of the main frame


1


A has an auxiliary reinforcing member


66


formed integrally therewith. The auxiliary reinforcing member


66


is placed substantially parallel to the reinforcing member


60


outside thereof at a predetermined interval. The auxiliary reinforcing member


66


is placed in a continuous manner described as follows: The auxiliary reinforcing member


66


extends from a certain point between the cantilever support


7


and the side wall


251


at the arm


6


along the longitudinal direction of the arm


6


within the arm


6


to one end of the cantilever support


7


. The auxiliary reinforcing member


66


is then curved in a semicircle shape within the cantilever support


7


to extend to one end of the bed


8


. The auxiliary reinforcing member


66


further extends from the one end of the cantilever support


7


along the bed


8


with in the bed


8


to the point adjacent to the side wall


251


opposing to the cantilever support


7


. As describe above, the parallel arrangement of the reinforcing member


60


and the auxiliary reinforcing member


66


leads to a uniform filling to the interior of the back panel wall


250


between the reinforcing member


60


and the auxiliary reinforcing member


66


with synthetic resin, thereby preventing weld line and shrinkage appearing on the back panel wall


250


. As a result, the main frame


1


A can obtain a good appearance.




Referring to FIG.


7


(


c


), the auxiliary reinforcing member


66


has the substantially semicircle cross section similar to that of the reinforcing member


60


. The auxiliary reinforcing member


66


has a hollow tubular shape having a hollow space


68


within the auxiliary reinforcing member


66


. The auxiliary reinforcing member


66


is formed integrally with the back panel wall


250


in a manner to project from the interior of the back panel wall


250


of the main frame


1


A. The reason why the auxiliary reinforcing member


66


has a tubular shape is the same as that of the reinforcing member


60


. Additionally, a method to form the auxiliary reinforcing member


66


is the same as that of the reinforcing member


60


.




The above arrangement of the auxiliary reinforcing member


66


ensures the rigidity of the back panel wall


250


. Therefore, a sewing machine including the above main frame


1


A can advantageously prevent horizontal and vertical vibrations of the main frame


1


A caused by the reciprocating motion of the needle


16


, thereby performing smooth stitch forming action




In the above embodiment, the main frame


1


A is provided with the reinforcing member


60


and the auxiliary reinforcing member


66


, while the frame cover


1


B does not has any reinforcing member and auxiliary reinforcing member (See FIG.


11


). The reason why frame cover


1


B has no reinforcing member is as follows: the main frame


1


A accommodates the stitch forming mechanism including the tope mechanism


3


for reciprocating the needle


16


and the lower mechanism


4


for rotating the rotary hook


23


. Therefore, vibrations or displacement are more easily induced to the main frame


1


A than the frame cover


1


B. However, the frame cover


1


B may be provided with a reinforcing member or an auxiliary reinforcing member, if necessary. In that case, the frame cover


1


B obtains stronger rigidity.




Inside Wall Reinforcing Rib




As shown in

FIGS. 4 and 5

, an inside wall reinforcing rib


70


for reinforcing the inner surface wall


51


of the main frame


1


A facing the space


9


is provided on the inside of the back panel wall


250


around the periphery of the space


9


. A lot of inside wall reinforcing ribs


70


are provided around the periphery of the space


9


from the joint of the arm


6


and the cantilever support


7


to the joint of the cantilever support


7


and the bed


8


.




The inside wall reinforcing rib


70


comprises a partitioning rib


71


spaced from the inner surface


51


and a plurality of intermediate ribs


72


intersecting with the inner surface


51


and partitioning rib


71


. The partitioning rib


71


extends from the inside of the back panel wall


250


and parallel and perpendicularly to the inner surface wall


51


in a continuous manner. The intermediate rib


72


extends from the inside of the back panel wall


250


between the inner surface wall


51


and the partitioning rib


71


at a constant intervals perpendicularly to the back panel wall


250


. The intermediate rib


72


connects the inner surface wall


51


to the partitioning rib


71


, and connects the inner surface wall


51


and the partitioning rib


71


to the back panel wall


250


. The above arrangement of the inner surface wall


51


, the partitioning rib


71


, and the intermediate ribs


72


provides a plurality of cells


73


in the space between the inner surface


51


and partitioning rib


71


. The intermediate ribs


72


are arranged radially from a center point located in the space


9


, because the inner surface wall


51


surrounding the space


9


has a semicircle shape. Accordingly, each intermediate rib


72


intersects the inner surface


51


and partitioning rib


71


at a perpendicular angle. Thus, the arrangement of the ribs is optimized, thereby reinforcing the inner surface wall


51


advantageously.




The above structure of the inside wall reinforcing ribs


70


provides the rigidity equal to that of the inner surface wall


51


having a considerable thickness. In other words, the above structure of the inside wall reinforcing ribs


70


ensures the rigidity over the back panel wall


250


from the area adjacent to the joint of the arm


6


and the cantilever support


7


, through the cantilever support


7


, to the area adjacent to the joint of the cantilever support


7


and the bed


8


. A sewing machine having the main frame


1


A can prevent horizontal and vertical vibrations of the main frame


1


A caused by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




In the above embodiment, the inside wall reinforcing ribs


70


are provided on the back panel wall


250


from the joint of the arm


6


and the cantilever support


7


through the


7


through the


7


to the joint of the cantilever support


7


and the bed


8


. In another embodiment, the inside wall reinforcing rib


70


may be formed over the whole of the inner surface wall


51


. In the above embodiment, a lot of intermediate ribs


72


are provided. However, in another embodiment, the number of the intermediate ribs


72


may be only one or a few. Each of the intermediate ribs


72


may be coupled or crossed to each other, so that the resultant arrangement of the intermediate ribs


72


may have honeycomb or diagram shape.




As described above, the hollow reinforcing member


60


having a substantially semicircle shape is formed integrally with the back panel wall


250


around the inner surface wall


51


. In other words, both the reinforcing member


60


and the inside wall reinforcing rib


70


are formed at the substantially same positions on the inner surface wall


51


. Especially, the reinforcing member


60


is located near the back panel wall


250


inside of the inside wall reinforcing rib


70


. The inside wall reinforcing rib


70


projects from the surface of the reinforcing member


60


. The above structure is necessary to obtain considerable reinforcement, because stress induced by the reciprocating motion of the needle


16


is concentrated on the inner surface wall


51


. In addition, the space around the inner surface wall


51


has sufficient spare room because the stitch forming mechanism is not mounted. Therefore, the inside wall reinforcing rib


70


having a considerable height can be formed.




Outside Wall Reinforcing Rib




As shown in

FIGS. 4 and 5

, outside wall reinforcing ribs


80


are formed in a matrix shape over nearly the entire inside of the back panel wall


250


. The outside wall reinforcing rib


80


projects from the inside of the back panel wall


250


. The outside wall reinforcing rib


80


is formed of vertical ribs


81


vertically oriented when the sewing machine is placed on a working surface, and horizontal ribs


82


oriented horizontally when the sewing machine is in the same position. As shown in FIGS.


6


(A) and


6


(B), these vertical ribs


81


and horizontal ribs


82


are approximately perpendicular to the back panel wall


250


. The ends of the vertical ribs


81


and horizontal ribs


82


are joined with the side wall


251


on the side portions of the main frame


1


A. The spaces surrounded by pairs of intersecting vertical ribs


81


,


81


and horizontal ribs


82


,


82


form approximately square or rectangular shaped cells


83


. Hence, a plurality of cells


83


are formed on the back side of the back panel wall


250


.




Among the cells


83


, the outside wall reinforcing rib


80


defining a cell


83


having a wider area is formed to have a higher height from the back panel wall


250


, compared to a cell


83


having a narrower area. The above structure of the cell


83


will be explained with respect to a wider cell


83


A located on the right side of the arm conducting shaft supports


144


in the cantilever support


7


(see FIGS.


4


and


5


), and a narrower cell


83


B located on the lower-right side of the needle bar holder mount


141


in the arm


6


(see FIGS.


4


and


5


).




As shown in

FIG. 5

, the vertical length X of the wider cell


83


A is identical to the vertical length U of the narrower cell


83


B. On the other hand, the horizontal length Y of the wider cell


83


A is longer more than two times of the horizontal length V of the narrower cell


83


B. Thus, the area of the wider cell


83


A is wider than that of the narrower cell


83


B.




Referring to FIG.


6


(A), the height Z from the


250


of the outside wall reinforcing rib


80


constituting the wider cell


83


A (horizontal rib


82


) is higher than the height W from the back panel wall


250


of the outside wall reinforcing rib


80


constituting the narrower cell


83


B (vertical rib


81


). In the case where the outside wall reinforcing ribs


80


have different height from each other due to requirements for a design of the main frame


1


A, the wider area of the higher outside wall reinforcing rib


80


and the narrower area of the narrower outside wall reinforcing rib


80


lead to the uniform rigidity over the whole of the back panel wall


250


. Accordingly, the action of stress on the particular point on the back panel wall


250


can be avoided. Thus, the main frame


1


A ensures considerable rigidity as a whole.




The outside wall reinforcing rib


80


on the accommodating part for the stitch forming mechanism in the arm


6


or the bed


8


has a lower height from the back panel wall


250


than those of the outside wall reinforcing ribs


80


on the inside of the back panel wall


250


other than the accommodating part. In other words, as described above, the narrower cell


83


B is located on the right-lower side of the needle bar holder mount


141


for mounting the needle bar holder


14


constituting the tope mechanism


3


, thereby corresponding to the part accommodating the stitch forming mechanism. Therefore, the outside wall reinforcing rib


80


(vertical rib


81


) has a relatively lower height W from the back panel wall


250


so as to face the stitch forming mechanism at a closer distance. On the other hand, the wider cell


83


A is not a part for accommodating the stitch forming mechanism. Accordingly, as described above, the outside wall reinforcing rib


80


(horizontal rib


82


) has a relatively higher height Z form the back panel wall


250


. However, the above structure may lead to insufficient rigidity over the part for accommodating the stitch forming mechanism. To overcome the above problem, the narrower area of the cell


83


, that is, the formation of the narrower cell


83


B, results in the increase of the rigidity thereof. The resultant rigidity is substantially the same as that of the wider cell


83


A. Accordingly, the concentration of stress to a certain point of the back panel wall


250


can be prevented, so that the main frame


1


A can obtain sufficient rigidity.




The above arrangement of the outside wall reinforcing rib


80


ensures the sufficient rigidity of the back panel wall


250


, thereby minimizing or restricting distortion appearing on the back panel wall


250


of the arm


6


due to the reciprocating motion of the needle


16


. The above arrangement of the outside wall reinforcing rib


80


also minimizes distortion appearing on the back panel wall


250


of the cantilever support


7


and the bed


8


due to the distortion of the arm


6


. In this embodiment, the outside wall reinforcing ribs


80


extend in vertical and horizontal directions on the back panel wall


250


to define the cells


83


. This arrangement results in the sufficient rigidity of the back panel wall


250


in the case where the outside wall reinforcing rib


80


is not allowed to have a higher height in order that the main frame


1


A accommodates the stitch forming mechanism. Accordingly, a sewing machine having the above main frame


1


A can prevent vertical and horizontal vibrations of the main frame


1


A caused by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




In another embodiment, the outside wall reinforcing rib


80


may not be formed over the whole back panel wall


250


, but be formed over only the part of the back panel wall


250


which needs sufficient rigidity of the back panel wall


250


for accommodating the stitch forming mechanism. In another embodiment, the outside wall reinforcing ribs


80


may be arranged in order that the cells


83


have hexagonal or octagonal shapes.




It should be noted that the inside wall reinforcing rib


70


has a higher height from the back panel wall


250


than that of the outside wall reinforcing rib


80


. More specifically, as shown in FIG.


8


(A), at the base end of the arm


6


, the inside wall reinforcing rib


70


is formed at a height from the back panel wall


250


reaching the dividing plane


52


. In contrast, the vertical ribs


81


reach approximately halfway to the dividing plane


52


from the back panel wall


250


. As shown in FIG.


8


(B), in the center portion of the cantilever support


7


, the intermediate ribs


72


have a height from the sidewall


50


reaching the dividing plane


52


. In contrast, the horizontal ribs


82


reach less than half the height of the dividing plane


52


from the sidewall


50


. A high rigidity is necessary for the inner surface wall


51


since stress generated by the vertical movement of the needle


16


is concentrated in this area. On the other hand, these height differences are necessary to maintain space at the inside of the back panel wall


250


for accommodating the stitch forming mechanism including the top mechanism


3


and the lower mechanism


4


.




Couplings




As shown in

FIGS. 4 and 5

, a plurality of couplings


90


,


92


,


94


, and


96


are provided in the back panel wall


250


of the main frame


1


A for joining the main frame


1


A to the frame cover


1


B. The coupling


90


is formed near the inner surface wall


51


in the area adjacent to the joint of the bed


8


and the cantilever support


7


. More specially, the coupling


90


is placed in the vicinity of the inside wall reinforcing rib


70


and the reinforcing member


60


. The above arrangement of the coupling


90


is aimed at preventing distortion of the arm


6


and the cantilever support


7


which causes swings of the top portion of the cantilever support


7


during the reciprocating motion of the needle


16


. The coupling


92


is formed near the inner surface wall


51


at the joint area of the arm


6


and the cantilever support


7


. More particularly, the coupling


92


is placed in the vicinity of the inside wall reinforcing rib


70


and the reinforcing member


60


. The coupling


94


is formed near the inner surface wall


51


in the vicinity of the end of the inside wall reinforcing rib


70


near the arm


6


. The couplings


92


,


94


are placed on the circumference of the semicircle of the space


9


at constant intervals with respect to the coupling


90


. A plurality of couplings


96


are formed on the sides and the corners of the inside of the back panel wall


250


in order to couple the main frame


1


A and the frame cover


1


B by a uniform pressure.




Screw holes


91


,


93


,


95


, and


97


are formed inside the couplings


90


,


92


,


94


, and


96


. The main frame


1


A and frame cover


1


B can be detachably joined together by inserting screws (not shown) in the screw holes


91


,


93


,


95


, and


97


when the couplings


90


,


92


,


94


, and


96


are aligned with couplings


190


,


192


,


194


, and


196


(see

FIG. 11

) provided in corresponding positions on the frame cover


1


B. Accordingly, the sewing machine is easily assembled by mounting the stitch forming mechanism to the main frame


1


A, and then screwing the frame cover


1


B to the main frame


1


A, thereby enabling cost reductions. In the case of maintenance, only undoing the screws leads to remove of the frame cover


1


B from the main frame


1


A, so that all the stitch forming mechanism is exposed. Therefore, the maintenance work is facilitated. In the present embodiment, screws are used to join the main frame


1


A to the frame cover


1


B, but bolts and nuts may also be used in place of the screws.




When stress induced by the reciprocating motion of the needle


16


forces the inner surface wall


51


of the main frame


1


A and an inner surface wall


161


of the frame cover


1


B to relatively move in a vertical or horizontal directions, relative movement of the main frame


1


A and the frame cover


1


B is restricted because a plurality of couplings


190


,


192


, and


194


(see

FIG. 11

) are arranged around the inner surface walls


51


,


161


. Therefore, the inner surface wall


51


of the main frame


1


A remains contact with the inner surface wall


161


of the frame cover


1


B. A appropriate coupling between the main frame


1


A and the frame cover


1


B is maintained. Stress is transmitted from the main frame


1


A including the stitch forming mechanism which generates vibrations to the frame cover


1


B through the inner surface walls


51


,


161


which are contact to each other, thereby dispersing over the whole frame


1


. The stress dispersion ensures the sufficient rigidity of the frame


1


. As a result, a sewing machine including the frame


1


can prevent vertical vibrations and horizontal swings of the frame


1


induced by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




In another embodiment, two or more than four couplings may be formed around the inner surface wall


51


of the main frame


1


A.




Protrusions




As shown in

FIG. 4

, protrusions


100


,


101


,


102


, and


103


are formed on the main frame


1


A at the dividing plane


52


. These protrusions


100


,


101


,


102


, and


103


engage with engaging units


111


,


112


,


113


, and


114


provided on the frame cover


1


B at the dividing plane


52


(see

FIG. 11

) when the main frame


1


A is joined with the frame cover


1


B. The protrusions


100


,


101


,


102


, and


103


are aimed at limiting the relative movement of the main frame


1


A and frame cover


1


B in the horizontal direction.




Next, the reason that the sewing machine frame of the present invention is configured in this way will be described. As mentioned earlier, a swing effect occurs in the horizontal direction in the top portion of the cantilever support


7


due to the vertical movement of the needle


16


. When this happens, the main frame


1


A and frame cover


1


B can move relative to one another in the horizontal direction, shifting their relative positions. When this positional shifting occurs, a reliable joined state cannot be maintained, resulting in insufficient rigidity, thereby promoting vibrations and displacement in the frame


1


. Moreover, the main frame


1


A and frame cover


1


B are joined by screws through considerable pressure, causing a large frictional coefficient. As a result, when the relative position of the main frame


1


A and frame cover


1


B shifts, they do not easily return to their original positions. The above construction is employed because it is necessary to prevent such shifting in the relative position of the main frame


1


A and frame cover


1


B from occurring. With this construction, it is possible to maintain sufficient rigidity in the frame


1


.




As shown in FIG.


9


(A), the protrusion


100


protrudes from the bottom of the arm


6


at the dividing plane


52


substantially perpendicular to the frame cover


1


B and near the border between the horizontal portion on which the mechanism for reciprocally driving the needle


16


is supported and the semicircular portion by which the space


9


is formed. An opening


143


is formed in the front end of the arm


6


from which the reciprocally driving mechanism protrudes downward. The protrusion


100


is positioned to one side of the opening


143


. The protrusion


100


fits in the engaging unit


111


provided on the arm


6


of the frame cover


1


B (see FIG.


11


). This configuration prevents relative movement of the main frame


1


A and frame cover


1


B generated by vibrations and displacement at the dividing plane


52


of arm


6


.




As shown in FIG.


9


(B), the protrusions


101


and


102


protrude from the top of the bed


8


at the dividing plane


52


, that is, at both ends of an opening


149


approximately perpendicular to the frame cover


1


B. The opening


149


is aimed for exposing rotary hook


23


. The protrusions


101


,


102


are fitted into engaging units


112


,


113


provided in the bed


8


of the frame cover


1


B (see FIG.


11


). The above arrangement can prevent relative movement of both the main frame


1


A and the frame cover


1


B caused by vibrations and displacement at the dividing plane


52


of the bed


8


in the main frame


1


A and the frame cover


1


B.




Referring to FIGS.


8


(B),


8


(C), the protrusion


103


protrudes to the frame cover


1


B being coupled at a predetermined point on the dividing plane


52


around the space


9


. The predetermined point is placed on the intermediate rib


72


constituting the inside wall reinforcing rib


70


in the vicinity of a cross point with the inner surface wall


51


around the space


9


. The protrusion


103


fits a channel-shaped engaging unit


114


(see

FIG. 11

) provided the periphery of the frame cover


1


B facing the space


9


. The above structure prevents vibrations and displacement at the dividing plane


52


around space


9


, thereby restricting relative movement of the coupled main frame


1


A and frame cover


1


B.




Referring to FIG.


9


(A), an engaging unit


110


for receiving the protrusion


104


(see

FIG. 11

) protruding from the dividing plane


52


below the arm


6


of the frame cover


1


B. The place of the engaging unit


110


is on the dividing plane


52


below the arm


6


of the main frame


1


A. The above arrangement prevents vibrations and displacement at the dividing plane


52


of the arm


6


of the coupled main frame


1


A and frame cover


1


B, thereby restricting relative movement of the main frame


1


A and frame cover


1


B.




Top Edge




As shown in FIGS.


4


and


7


(A), a top edge


120


is formed across the top of the main frame


1


A for contacting the frame cover


1


B. A raised step


121


is formed across nearly the entire top edge


120


, the bottom of raised step


121


protruding toward the frame cover


1


B. The protruding portion of the raised step


121


fits into a recessed step


126


formed in a top edge


125


of the frame cover


1


B for contacting the main frame


1


A (see FIG.


11


). By engaging the raised step


121


with the recessed step


126


from above, this construction can limit the relative movement of the main frame


1


A in the upward direction.




Next, the reason that the sewing machine frame of the present invention is configured in this way will be described. As mentioned earlier, the portion of the main frame


1


A near the arm


6


vibrates in the vertical direction due to the vertical movement of the needle


16


. In particular, the main frame


1


A on which the top mechanism


3


is mounted for supporting the needle


16


tends to move in the upward direction. When this happens, the main frame


1


A and frame cover


1


B can move relative to one another in the vertical direction, shifting their relative positions. When this positional shifting occurs, a reliable joined state cannot be maintained, resulting in insufficient rigidity, thereby promoting vibrations and displacement in the frame


1


. Moreover, the main frame


1


A and frame cover


1


B are joined by screws through considerable pressure, causing a large frictional coefficient. As a result, when the relative position of the main frame


1


A and frame cover


1


B shifts, they do not easily return to their original positions. The above construction is employed because it is necessary to prevent such shifting in the relative position of the main frame


1


A and frame cover


1


B from occurring. With this construction, it is possible to maintain sufficient rigidity in the frame


1


.




While the raised step


121


in the present embodiment is formed across nearly the entire length of the top edge


120


of the main frame


1


A that contacts the frame cover


1


B, it is not necessary for the raised step


121


to span the entire length of the top edge


120


. In view of the reason described above for forming the raised step


121


, however, it is desirable that the raised step


121


be formed on the top edge


120


at least at portions of the main frame


1


A corresponding to the arm


6


. Similarly, the recessed step


126


(see

FIG. 11

) should be formed on the top edge


125


at least on portions of the frame cover


1


B that correspond to the arm


6


. With this construction, it is possible to achieve sufficient rigidity for the arm


6


.




A bottom edge


130


is formed across the bottom of the main frame


1


A for contacting the frame cover


1


B. A raised step


131


is formed across nearly the entire length of the bottom edge


130


, the top of the raised step


131


protruding toward the frame cover


1


B. As shown in FIG.


7


(B), the raised step


131


comprises an insertion part


132


for inserting into a recessed step


136


(see

FIG. 11

) formed on a bottom edge


135


of the frame cover


1


B for contacting the main frame


1


A; a sliding surface


133


for guiding the raised step


131


into the recessed step


136


; and an engaging wall


134


for engaging in the recessed step


136


after the recessed step


136


has been slid to a prescribed position. By inserting the insertion part


132


in the recessed step


136


of the frame cover


1


B and engaging the sliding surface


133


with the bottom of the recessed step


136


, it is possible to limit relative movement of the main frame


1


A in the downward direction.




Next, the reason that the sewing machine frame of the present invention is configured in this way will be described. As mentioned earlier, the portion of the main frame


1


A tends to move upward due to the vertical movement of the needle


16


. When this happens, the bed


8


of the frame cover


1


B engaged with the main frame


1


A attempts to move downward relative to the main frame


1


A. As a result, the frame cover


1


B shifts vertically from the main frame


1


A, promoting the generation of vibrations and displacement in the frame


1


. Hence, it is necessary to prevent such shifting in the relative position of the main frame


1


A and frame cover


1


B from occurring. With this construction, it is possible to maintain sufficient rigidity in the frame


1


.




While the raised step


131


in the present embodiment is formed across nearly the entire length of the bottom edge


130


of the main frame


1


A that contacts the frame cover


1


B, it is not necessary for the raised step


131


to span the entire length of the bottom edge


130


. In view of the reason described above for forming the raised step


131


, however, it is desirable that the raised step


131


be formed on the bottom edge


130


at least at portions of the main frame


1


A corresponding to the bed


8


. Similarly, the recessed step


136


(see

FIG. 11

) should be formed on the bottom edge


135


at least on portions of the frame cover


1


B that correspond to the bed


8


. With this construction, it is possible to achieve sufficient rigidity for the bed


8


.




Here, the sliding surface


133


of the raised step


131


is retracted further internally than the back panel wall


250


of the main frame


1


A. When the recessed step


136


of the frame cover


1


B overlaps this portion, the sidewall of the main frame


1


A and frame cover


1


B become the same height. Accordingly, by engaging the main frame


1


A with the frame cover


1


B, the sidewall of the main frame


1


A and frame cover


1


B forms a continuous surface at this point, improving the appearance of the frame


1


.




While a detailed construction of the raised step


121


described above is not shown in the drawings, this construction is similar to the raised step


131


of the bottom edge


130


shown in FIG.


7


(B). However, the raised step


121


is vertically symmetrical to the raised step


131


.




Flame Cover




Next, the frame cover


1


B of the frame


1


will be described with reference to FIG.


10


through needle bar


15


.

FIG. 10

is a perspective view showing the external appearance of the frame cover


1


B.

FIG. 11

is a perspective view showing the internal construction of the frame cover


1


B.

FIG. 12

is a plan view showing the internal construction of the frame cover


1


B.

FIG. 13

is a cross-sectional view along the plane of the frame cover


1


B indicated by the arrows I in FIG.


12


. FIG.


14


(A) is a cross-sectional view along the plane of the frame cover


1


B indicated by the arrows J in FIG.


12


. FIG.


14


(B) is an enlarged view showing the lower end of the frame cover


1


B. FIG.


15


(A) is an enlarged plan view along the plane of the frame cover


1


B indicated by the arrows K in FIG.


12


. FIG.


15


(B) is an enlarged plan view along the plane of the frame cover


1


B indicated by the arrows L in FIG.


12


.




As shown in

FIG. 10

, the frame cover


1


B comprises the arm


6


, cantilever support


7


, and bed


8


, and is integrally formed of a synthetic resin with the arm


6


, cantilever support


7


, and bed


8


. The semicircular area surrounded by the arm


6


, cantilever support


7


, and bed


8


is the space


9


the main frame


1


A substantially comprises the arm


6


, the cantilever support


7


, and the bed


8


formed integrally. The semicircular space surrounded by the arm


6


, cantilever support


7


, and bed


8


is a space


9


.




In addition, the frame cover


1


B comprises a front panel wall


252


constituting a front side of the sewing machine, and side wall


253


extending from a peripheral edge


252




a


of the front panel wall


252


. Especially, the surface of the frame cover


1


B facing the space


9


is designated as an inner surface wall


161


. A side portion of the arm


6


is provided with a thread cassette mount


203


in which a thread cassette including different kinds of thread.




Inside Wall Reinforcing Rib




As shown in

FIGS. 11 and 12

, an inside wall reinforcing rib


170


for reinforcing the inner surface wall


161


of the frame cover


1


B facing the space


9


is provided on the inside of the front panel wall


252


around the periphery of the space


9


. A lot of inside wall reinforcing ribs


170


are provided around the periphery of the space


9


from the joint of the arm


6


and the cantilever support


7


to the joint of the cantilever support


7


and the bed


8


in order to surround the inner surface wall


161


.




The inside wall reinforcing rib


170


comprises a partitioning rib


171


spaced from the inner surface


161


and a plurality of intermediate ribs


172


intersecting with the inner surface


161


and partitioning rib


171


. The partitioning rib


171


extends from the inside of the front panel wall


252


and parallel and perpendicularly to the inner surface wall


161


in a continuous manner. The intermediate rib


172


extends from the inside of the front panel wall


252


between the inner surface wall


161


and the partitioning rib


171


at a constant intervals perpendicularly to the front panel wall


252


. The intermediate rib


172


connects the inner surface wall


161


to the partitioning rib


171


, and connects the inner surface wall


161


and the partitioning rib


171


to the front panel wall


252


. The above arrangement of the inner surface wall


161


, the partitioning rib


171


, and the intermediate ribs


172


provides a plurality of cells


173


in the space between the inner surface


161


and partitioning rib


171


. The intermediate ribs


172


are arranged radially from a center point located in the space


9


, because the inner surface wall


161


surrounding the space


9


has a semicircle shape. Accordingly, each intermediate rib


172


intersects the inner surface


161


and partitioning rib


171


at a perpendicular angle. Thus, the arrangement of the ribs is optimized, thereby reinforcing the inner surface wall


161


advantageously.




The above structure of the inside wall reinforcing ribs


170


provides the rigidity equal to that of the inner surface wall


161


having a considerable thickness. In other words, the above structure of the inside wall reinforcing ribs


170


ensures the rigidity over the front panel wall


252


from the area adjacent to the joint of the arm


6


and the cantilever support


7


, through the cantilever support


7


, to the area adjacent to the joint of the cantilever support


7


and the bed


8


. A sewing machine having the frame cover


1


B can prevent horizontal vibrations and swings of the frame cover


1


B caused by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




In the above embodiment, the inside wall reinforcing ribs


170


are provided on the front panel wall


252


from the joint of the arm


6


and the cantilever support


7


through the


7


through the


7


to the joint of the cantilever support


7


and the bed


8


. In another embodiment, the inside wall reinforcing rib


170


may be formed over the whole of the inner surface wall


161


. In the above embodiment, a lot of intermediate ribs


172


are provided. However, in another embodiment, the number of the intermediate ribs


172


may be only one or a few. Each of the intermediate ribs


172


may be coupled or crossed to each other, so that the resultant arrangement of the intermediate ribs


172


may have a honeycomb or diagram shape.




In order to further support the partitioning rib


171


of the inside wall reinforcing ribs


170


, a supplemental concave wall reinforcing rib


177


is provided outside of the inside wall reinforcing ribs


170


. The supplemental concave wall reinforcing rib


177


comprises an auxiliary partitioning rib


174


and a plurality of auxiliary intermediate ribs


175


. The auxiliary partitioning rib


174


is provided in a continuous manner along the partitioning rib


171


, while being spaced from the partitioning rib


171


. The auxiliary intermediate ribs


175


intersect the partitioning rib


171


and partitioning rib


174


at predetermined intervals, and form a plurality of cells or compartments


176


between the partitioning rib


171


and partitioning rib


174


. This construction attains further rigidity of the inner surface


161


of the space


9


. In another embodiment, supplemental concave wall reinforcing ribs may be provided outside of the inside wall reinforcing rib


70


of the main frame


1


A, if the main frame


1


A has sufficient spare space.




Outside Wall Reinforcing Rib




As shown in

FIGS. 11 and 12

, outside wall reinforcing ribs


180


are formed in a matrix shape over nearly the entire inside of the front panel wall


252


. The outside wall reinforcing rib


180


projects from the inside of the front panel wall


252


. The outside wall reinforcing rib


180


is formed of vertical ribs


181


vertically oriented when the sewing machine is placed on a working surface, and horizontal ribs


182


oriented horizontally when the sewing machine is in the same position. As shown in FIGS.


13


and


14


(A), these vertical ribs


181


and horizontal ribs


182


are approximately perpendicular to the front panel wall


252


. The ends of the vertical ribs


181


and horizontal ribs


182


are joined with the side wall


253


on the side portions of the frame cover


1


B. The upper ends of the vertical ribs


181


are not coupled to the side wall


253


. This is because the upper portion of the frame cover


1


B needs sufficient space to accommodate thread cassettes and an LED display substrate. The spaces surrounded by pairs of intersecting vertical ribs


181


,


181


and horizontal ribs


182


,


182


form approximately square or rectangular shaped cells


183


. Hence, a plurality of cells


183


are formed on the back side of the front panel wall


252


.




Among the cells


183


, the outside wall reinforcing rib


180


defining a cell


183


having a wider area is formed to have a higher height from the front panel wall


252


, compared to a cell


183


having a narrower area. The outside wall reinforcing rib


180


on the accommodating part for the stitch forming mechanism in the arm


6


or the bed


8


has a lower height from the front panel wall


252


than those of the outside wall reinforcing ribs


180


on the inside of the front panel wall


252


other than the accommodating part. The cells


183


in the vicinity of the accommodating part for the stitch forming mechanism have narrower areas than those of the cells


183


provided on the area other than the accommodating part. The reason the above arrangement has been adopted is the same as that of the main frame


1


A, so that detailed explanation will be omitted.




The above arrangement of the outside wall reinforcing rib


180


ensures the sufficient rigidity of the front panel wall


252


, thereby minimizing or restricting distortion appearing on the front panel wall


252


of the arm


6


due to the reciprocating motion of the needle


16


. The above arrangement of the outside wall reinforcing rib


180


also minimizes distortion appearing on the front panel wall


252


of the cantilever support


7


and the bed


8


due to the distortion of the arm


6


. In this embodiment, the outside wall reinforcing ribs


180


extend in vertical and horizontal directions on the front panel wall


252


to define the cells


183


. This arrangement results in the sufficient rigidity of the front panel wall


252


in the case where the outside wall reinforcing rib


180


is not allowed to have a higher height in order that the frame cover


1


B accommodates the stitch forming mechanism. Accordingly, a sewing machine having the above frame cover


1


B can prevent vertical and horizontal vibrations of the frame cover


1


B caused by the reciprocating motion of the needle


16


, thereby performing a smooth stitch forming action.




It should be noted that the inside wall reinforcing rib


170


has a higher height from the front panel wall


252


than that of the outside wall reinforcing rib


180


. More specifically, as shown in FIG.


14


(A), at the base end of the arm


6


, the inside wall reinforcing rib


170


is formed at a height from the front panel wall


252


reaching the dividing plane


52


. In contrast, the vertical ribs


181


reach approximately halfway to the dividing plane


52


from the front panel wall


252


. The reason is as follows: the inner surface wall


161


needs sufficient rigidity, because stress induced by the reciprocating motion of the needle


16


generally tends to concentrate on the inner surface wall


161


.




In another embodiment, the outside wall reinforcing rib


180


may be provided on the only part of the frame cover


1


B. Alternatively, the frame cover


1


B may have no outside wall reinforcing rib


180


. The frame cover


1


B does not need so high rigidity as that of the main frame


1


A.




Couplings




As shown in

FIGS. 11 and 12

, a plurality of couplings


190


,


192


,


194


, and


196


are provided in the front panel wall


252


of the main frame


1


A for joining the main frame


1


A to the frame cover


1


B. The coupling


190


,


192


,


194


, and


196


are placed at positions corresponding to the positions of the couplings


90


,


92


,


94


, and


94


of the main frame


1


A. The coupling


190


is formed near the inner surface wall


161


in the area adjacent to the joint of the bed


8


and the cantilever support


7


. More specially, the coupling


190


is placed in the vicinity of the inside wall reinforcing rib


170


formed outside of the inner surface wall


161


. The above arrangement of the coupling


190


is aimed at preventing distortion of the arm


6


and the cantilever support


7


which causes swings of the top portion of the cantilever support


7


during the reciprocating motion of the needle


16


. The coupling


192


is formed near the inner surface wall


161


at the joint area of the arm


6


and the cantilever support


7


. More particularly, the coupling


192


is placed in the vicinity of the inside wall reinforcing rib


170


outside of the inner surface wall


161


. The coupling


194


is formed near the inner surface wall


161


in the vicinity of the end of the inside wall reinforcing rib


170


near the arm


6


. The couplings


192


,


194


are placed on the circumference of the semicircle of the space


9


at constant intervals with respect to the coupling


190


. A plurality of couplings


196


are formed on the sides and the corners of the inside of the back panel wall


250


in order to couple the main frame


1


A and the frame cover


1


B by a uniform pressure.




Screw holes


191


,


193


,


195


, and


197


are formed inside the couplings


190


,


192


,


194


, and


196


. The main frame


1


A and frame cover


1


B can be detachably joined together by inserting screws (not shown) in the screw holes


191


,


193


,


195


, and


197


when the couplings


190


,


192


,


194


, and


196


are aligned with couplings


90


,


92


,


94


, and


96


provided in corresponding positions on the main frame


1


A.




Engaging Unit




As shown in

FIG. 11

, engaging units


111


,


112


,


113


, and


114


are formed in the frame cover


1


B at the dividing plane


52


. These engaging units


111


,


112


,


113


, and


114


engage with protrusions


100


,


101


,


102


, and


103


provided on the main frame


1


A at the dividing plane


52


(see

FIG. 4

) when the main frame


1


A is joined with the frame cover


1


B and function to limit the relative movement of the main frame


1


A and frame cover


1


B in the horizontal direction.




As shown in FIG.


15


(A), the engaging unit


111


is recessed in the bottom of the arm


6


on the frame cover


1


B at the dividing plane


52


and on one side of an opening


200


through which the mechanism for reciprocally driving the needle


16


protrudes downward. The engaging unit


111


engages with the protrusion


100


(see

FIG. 4

) formed on the arm


6


of the main frame


1


A. This construction limits relative movement of the main frame


1


A and frame cover


1


B generated by vibrations and displacement at the dividing plane


52


of the arm


6


.




As shown in FIG.


15


(B), the engaging units


112


and


113


are recessed in the top of the bed


8


at the dividing plane


52


and on both sides of an opening


202


for exposing the rotary hook


23


. The engaging units


112


and


113


engage with the protrusions


101


and


102


formed on the bed


8


of the main frame


1


A (see FIG.


4


). This construction restricts relative movement of the main frame


1


A and frame cover


1


B caused by vibrations and displacement at the dividing plane


52


of the bed


8


.




As shown in

FIG. 11

, the engaging unit


114


is formed in a continuous channel on the inner surface


161


of the space


9


. The protrusions


103


provided on the main frame


1


A (see

FIG. 4

) engage with this channel portion. This construction restricts relative movement of the main frame


1


A and frame cover


1


B caused by vibrations and displacement at the dividing plane


52


of the space


9


.




Protrusion




As shown in FIG.


15


(A), the protrusion


104


is formed on the bottom of the arm


6


of the frame cover


1


B at the dividing plane


52


and on the opposite side of the opening


200


as that in which the engaging unit


111


is formed. The protrusion


104


protrudes substantially perpendicularly to the frame cover


1


B. The protrusion


104


fits in the engaging unit


110


provided on the arm


6


of the main frame


1


A (see FIG.


4


). This construction restricts relative movement of the main frame


1


A and frame cover


1


B caused by vibrations and displacement at the dividing plane


52


of the arm


6


.




Recessed Top Edge




As shown in FIG.


14


(A), the recessed step


126


is formed across nearly the entire top edge


125


on the frame cover


1


B that contacts the main frame


1


A for accommodating the raised step


121


formed on the top edge


120


of the main frame


1


A and engaging the raised step


121


from the top. As shown in FIG.


14


(B), the recessed step


126


comprises an engaging wall


127


protruding toward the main frame


1


A for engaging the raised step


121


of the main frame


1


A when the raised step


121


is guided to a prescribed position; a sliding surface


128


for guiding the raised step


121


; and an accommodating portion


129


for accommodating the insertion part of the raised step


121


. By accommodating the insertion part of the raised step


121


in the accommodating portion


129


and when the sliding surface of the raised step


121


engages with the sliding surface


128


from above, it is possible to limit relative movement of the main frame


1


A in the upward direction.




The recessed step


136


is formed across nearly the entire bottom edge


135


of the frame cover


1


B that contacts the main frame


1


A for accommodating the raised step


131


formed on the bottom edge


130


of the main frame


1


A and engaging the raised step


131


from below. While a detailed construction of the recessed step


136


is not shown in the drawings, this construction is basically the same as the recessed step


126


of the top edge


125


shown in FIG.


14


(B). However, the recessed step


136


is vertically symmetrical to the recessed step


126


. By engaging the raised step


131


with the recessed step


136


, it is possible to limit the relative movement of the main frame


1


A in the downward direction.




It is understood that the foregoing description and accompanying drawings set forth the preferred embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the spirit and scope of the disclosed invention. Thus, it should be appreciated that the invention is not limited to the disclosed embodiments but may be practiced within the full scope of the appended claims.



Claims
  • 1. A sewing machine frame for use in a sewing machine comprising:a frame member formed of a synthetic resin and having a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion at a position above the bed portion, the bed portion, the tower portion and the arm portion being formed integrally and providing a concaved peripheral wall defining a stitch working space; and a peripheral wall reinforcing rib protruding from the frame member, the peripheral wall reinforcing rib extending along the peripheral wall and ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.
  • 2. The sewing machine frame as claimed in claim 1, wherein the peripheral wall reinforcing rib comprises:an elongated rib extending substantially along the peripheral wall and positioned spaced away therefrom; and a plurality of sectioning ribs each extending from the peripheral wall in a direction to intersect with the elongated rib for providing a plurality of partitioning cells defined by the peripheral wall, the elongated rib and the plurality of sectioning ribs.
  • 3. The sewing machine frame as claimed in claim 2, wherein the elongated rib extends continuously along the peripheral wall.
  • 4. The sewing machine frame as claimed in claim 3, wherein the peripheral wall is in a form of a semi-circular shape, and, wherein the plurality of sectioning ribs extend in a radial direction of the semi-circular shaped peripheral wall.
  • 5. A sewing machine frame for use in a sewing machine comprising:an outer panel wall constituting a front wall and a rear wall, the outer panel wall having a peripheral edge; a side wall protruding from the peripheral edge to provide a closed space with the outer panel wall and being formed integrally with the outer panel wall with a synthetic resin, a combination of the outer panel wall and the side wall providing a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion and positioned above the bed portion, the side wall having a part providing a concaved peripheral wall which defines a stitch working space surrounded by the bed portion, the tower portion and the arm portion; a peripheral wall reinforcing rib protruding from the outer panel wall and extending along the peripheral wall, the peripheral wall reinforcing rib ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion; and an outer panel wall reinforcing rib protruding from the outer panel wall for reinforcing the same.
  • 6. The sewing machine frame as claimed in claim 5, wherein the peripheral wall reinforcing rib has a height from the outer panel wall higher than that of the outer panel wall reinforcing rib.
  • 7. The sewing machine frame as claimed in claim 6, wherein the outer panel wall reinforcing rib is provided at substantially entire area of the outer panel wall, and comprises a plurality of horizontally extending ribs, and a plurality of vertically extending ribs intersecting with the horizontally extending ribs for defining a plurality of isolating cells.
  • 8. The sewing machine frame as claimed in claim 5, further comprising a reinforcing member at a position between the outer panel wall and the peripheral wall reinforcing rib and provided integrally with the outer panel wall and the peripheral wall reinforcing rib, the reinforcing member having a generally semi-circular hollow cross-section, and having one end portion positioned in the arm portion and extending in a longitudinal direction thereof, and having another end portion positioned in the bed portion and extending in a longitudinal direction thereof.
  • 9. A sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, a stitch forming mechanism of the sewing machine being assembled in the sewing machine frame; the sewing machine frame comprising:an integral main frame body made from a synthetic resin and to which the stitch forming mechanism is assembled, the integral main frame body comprising a back panel wall having a first peripheral edge, and a first side wall integrally protruding from the first peripheral edge, the integral main frame body providing an arm section, a tower section and a bed section; an integral frame cover made from a synthetic resin and attached to the main frame body, the integral frame cover comprising a front panel wall having a second peripheral edge, and a second side wall integrally protruding from the second peripheral edge for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the bed section, and a complementary arm section to form the arm portion with the arm section, the first side wall and the second side wall having parts defining a concave wall surroundingly provided by the combination of the arm portion, the tower portion, and the bed portion; and a concave wall reinforcing rib extending along the concave wall and ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.
  • 10. The sewing machine frame as claimed in claim 9, wherein the concave wall reinforcing rib has an outer peripheral portion, and the sewing machine frame further comprising a supplemental concave wall reinforcing rib positioned at the outer peripheral portion for reinforcing the concave wall reinforcing rib.
  • 11. A sewing machine frame for use in a sewing machine comprising:an outer panel wall constituting a front wall and a rear wall, the outer panel wall having a peripheral edge; a side wall protruding from the peripheral edge to provide a closed space with the outer panel wall and being formed integrally with the outer panel wall with a synthetic resin, a combination of the outer panel wall and the side wall providing a bed portion extending in its longitudinal direction, a tower portion upstanding from the bed portion, and an arm portion extending in its longitudinal direction from the tower portion and positioned above the bed portion, and a congregated area among the bed portion, the tower portion and the arm portion providing a peripheral wall defining a stitch working space of the sewing machine; and a reinforcing member formed integrally with the outer panel wall and having a hollow cross-section, the reinforcing member being positioned along the peripheral wall and having one end portion positioned in the arm portion and extending in the longitudinal direction thereof, and having another end portion positioned in the bed portion and extending in the longitudinal direction thereof.
  • 12. The sewing machine frame as claimed in claim 11, wherein the reinforcing member has a generally semi-circular cross-section.
  • 13. The sewing machine frame as claimed in claim 11, wherein the arm portion has a base end connected to the tower portion, and a free end defined by the side wall; andwherein the one end portion of the reinforcing member has a tip end positioned adjacent to the free end.
  • 14. The sewing machine frame as claimed in claim 11, wherein the bed portion has a base end connected to the tower portion, and a free end portion defined by the side wall; andwherein the another end portion of the reinforcing member has a tip end positioned adjacent to the free end of the bed portion.
  • 15. The sewing machine frame as claimed in claim 11, further comprising a supplemental reinforcing member provided integrally with the outer panel wall and extending substantially in parallel with the reinforcing member.
  • 16. A sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, a stitch forming mechanism of a sewing machine being assembled in the sewing machine frame; the sewing machine frame comprising:an integral main frame body made from a synthetic resin and to which the stitch forming mechanism is assembled, the integral main frame body comprising a back panel wall having a peripheral edge, and a side wall integrally protruding from the peripheral edge, the integral main frame body providing an arm section, a tower section and a bed section, the side wall having a part defining a peripheral wall surroundingly provided by the combination of the arm section, the tower section and the bed section; an integral frame cover serving as a front panel wall made from a synthetic resin and attached to the main frame body for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the tower section, and a complementary arm section to form the arm portion with the arm section; and a reinforcing member formed integrally with the main frame body and having a hollow cross-section, the reinforcing member being positioned along the peripheral wall and having one end portion positioned in the arm section and extending in the longitudinal direction thereof, and having another end portion positioned in the bed section and extending in the longitudinal direction thereof.
  • 17. The sewing machine frame as claimed in claim 16, wherein the reinforcing member has a generally semi-circular cross-section.
  • 18. The sewing machine frame as claimed in claim 16, wherein the arm section has a base end connected to the tower section, and a free end defined by the side wall; andwherein the one end portion of the reinforcing member has a tip end positioned adjacent to the free end.
  • 19. The sewing machine frame as claimed in claim 16, wherein the bed section has a base end connected to the tower section, and a free end portion defined by the side wall; andwherein the another end portion of the reinforcing member has a tip end positioned adjacent to the free end of the bed section.
  • 20. The sewing machine frame as claimed in claim 16, further comprising a supplemental reinforcing member provided integrally with the main frame body and extending substantially in parallel with the reinforcing member.
  • 21. A sewing machine comprising:a stitch forming mechanism; and a sewing machine frame comprising a frame member formed of a synthetic resin and having a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion at a position above the bed portion, the bed portion, the tower portion and the arm portion being formed integrally and providing a peripheral wall defining a stitch working space surrounded by the bed portion, the tower portion and the arm portion; and a peripheral wall reinforcing rib protruding from the frame member, the peripheral wall reinforcing rib extending along the peripheral wall and ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.
  • 22. The sewing machine as claimed in claim 21, wherein the peripheral wall reinforcing rib comprises:an elongated rib extending substantially along the peripheral wall and positioned spaced away therefrom; and a plurality of sectioning ribs each extending from the peripheral wall in a direction to intersect with the elongated rib for providing a plurality of partitioning cells defined by the peripheral wall, the elongated rib and the plurality of sectioning ribs.
  • 23. The sewing machine as claimed in claim 22, wherein the elongated rib extends continuously along the peripheral wall.
  • 24. The sewing machine as claimed in claim 23, wherein the peripheral wall is in a form of a semi-circular shape, and, wherein the plurality of sectioning ribs extend in a radial direction of the semi-circular shaped peripheral wall.
  • 25. A sewing machine comprising:a stitch forming mechanism; and a sewing machine frame comprising an outer panel wall constituting a front wall and a rear wall, the outer panel wall having a peripheral edge; a side wall protruding from the peripheral edge to provide a closed space with the outer panel wall and being formed integrally with the outer panel wall with a synthetic resin, a combination of the outer panel wall and the side wall providing a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion and positioned above the bed portion, the side wall having a part providing a peripheral wall at a congregated area among the bed portion, the tower portion and the arm portion for defining a stitch working space surrounded by the bed portion, the tower portion and the arm portion; a peripheral wall reinforcing rib protruding from the outer panel wall and extending along the peripheral wall, the peripheral wall reinforcing rib ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion; and an outer panel wall reinforcing rib protruding from the outer panel wall for reinforcing the same.
  • 26. The sewing machine as claimed in claim 25, wherein the peripheral wall reinforcing rib has a height from the outer panel wall higher than that of the outer panel wall reinforcing rib.
  • 27. The sewing machine as claimed in claim 26, wherein the outer panel wall reinforcing rib is provided at substantially entire area of the outer panel wall, and comprises a plurality of horizontally extending ribs, and a plurality of vertically extending ribs intersecting with the horizontally extending ribs for defining a plurality of isolating cells.
  • 28. The sewing machine as claimed in claim 25, further comprising a reinforcing member at a position between the outer panel wall and the peripheral wall reinforcing rib and provided integrally with the outer panel wall and the peripheral wall reinforcing rib, the reinforcing member having a hollow cross-section, and having one end portion positioned in the arm portion and extending in a longitudinal direction thereof, and having another end portion positioned in the bed portion and extending in a longitudinal direction thereof.
  • 29. The sewing machine as claimed in claim 28, wherein the reinforcing member has a generally semi-circular cross-section.
  • 30. A sewing machine comprisinga stitch forming mechanism; and a sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, the stitch forming mechanism being assembled in the sewing machine frame; the sewing machine frame comprising: an integral main frame body made from a synthetic resin and to which the stitch forming mechanism is assembled, the integral main frame body comprising a back panel wall having a first peripheral edge, and a first side wall integrally protruding from the first peripheral edge, the integral main frame body providing an arm section, a tower section and a bed section; an integral frame cover made from a synthetic resin and attached to the main frame body, the integral frame cover comprising a front panel wall having a second peripheral edge, and a second side wall integrally protruding from the second peripheral edge for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the bed section, and a complementary arm section to form the arm portion with the arm section, the first side wall and the second side wall having parts defining a concave wall surroundingly provided by the combination of the arm portion, the tower portion, and the bed portion; and a concave wall reinforcing rib extending along the concave wall and ranging at least from a boundary between the bed portion and the tower portion to a boundary between the tower portion and the arm portion.
  • 31. The sewing machine frame as claimed in claim 30, wherein the concave wall reinforcing rib has an outer peripheral portion, and the sewing machine frame further comprising a supplemental concave wall reinforcing rib positioned at the outer peripheral portion for reinforcing the concave wall reinforcing rib.
  • 32. A sewing machine comprising:a stitch forming mechanism; and a sewing machine frame comprising: an outer panel wall constituting a front wall and a rear wall, the outer panel wall having a peripheral edge; a side wall protruding from the peripheral edge to provide a closed space with the outer panel wall and being formed integrally with the outer panel wall with a synthetic resin, a combination of the outer panel wall and the side wall providing a bed portion extending in its longitudinal direction, a tower portion upstanding from the bed portion, and an arm portion extending in its longitudinal direction from the tower portion and positioned above the bed portion, and a congregated area among the bed portion, the tower portion and the arm portion providing a peripheral wall defining a stitch working space; and a reinforcing member formed integrally with the outer panel wall and having a hollow cross-section, the reinforcing member being positioned along the peripheral wall and having one end portion positioned in the arm portion and extending in the longitudinal direction thereof, and having another end portion positioned in the bed portion and extending in the longitudinal direction thereof.
  • 33. The sewing machine as claimed in claim 32, wherein the reinforcing member has a generally semi-circular cross-section.
  • 34. The sewing machine as claimed in claim 32, wherein the arm portion has a base end connected to the tower portion, and a free end defined by the side wall; andwherein the one end portion of the reinforcing member has a tip end positioned adjacent to the free end.
  • 35. The sewing machine as claimed in claim 32, wherein the bed portion has a base end connected to the tower portion, and a free end portion defined by the side wall; andwherein the another end portion of the reinforcing member has a tip end positioned adjacent to the free end of the bed portion.
  • 36. The sewing machine frame as claimed in claim 32, further comprising a supplemental reinforcing member provided integrally with the outer panel wall and extending substantially in parallel with the reinforcing member.
  • 37. A sewing machine comprising:a stitch forming mechanism; and a sewing machine frame including a bed portion, a tower portion upstanding from the bed portion, and an arm portion extending from the tower portion in a cantilevered fashion, the stitch forming mechanism being assembled in the sewing machine frame; the sewing machine frame comprising: an integral main frame body made from a synthetic resin and to which the stitch forming mechanism is assembled, the integral main frame body comprising a back panel wall having a peripheral edge, and a side wall integrally protruding from the peripheral edge, the integral main frame body providing an arm section, a tower section and a bed section, the side wall having a part defining a peripheral wall surroundingly provided by the combination of the arm section, the tower section and the bed section; an integral frame cover serving as a front panel wall made from a synthetic resin and attached to the main frame body for providing a complementary bed section to form the bed portion with the bed section, a complementary tower section to form the tower portion with the tower section, and a complementary arm section to form the arm portion with the arm section; and a reinforcing member formed integrally with the main frame body and having a hollow cross-section, the reinforcing member being positioned along the peripheral wall and having one end portion positioned in the arm section and extending in the longitudinal direction thereof, and having another end portion positioned in the bed section and extending in the longitudinal direction thereof.
  • 38. The sewing machine as claimed in claim 37, wherein the reinforcing member has a generally semi-circular cross-section.
  • 39. The sewing machine as claimed in claim 37, wherein the arm section has a base end connected to the tower section, and a free end defined by the side wall; andwherein the one end portion of the reinforcing member has a tip end positioned adjacent to the free end.
  • 40. The sewing machine as claimed in claim 37, wherein the bed section has a base end connected to the tower section, and a free end portion defined by the side wall; andwherein the another end portion of the reinforcing member has a tip end positioned adjacent to the free end of the bed section.
  • 41. The sewing machine as claimed in claim 37, further comprising a supplemental reinforcing member provided integrally with the main frame body and extending substantially in parallel with the reinforcing member.
Priority Claims (3)
Number Date Country Kind
P2001-295559 Sep 2001 JP
P2001-295560 Sep 2001 JP
P2002-277137 Sep 2002 JP
US Referenced Citations (7)
Number Name Date Kind
2411459 Perkins et al. Nov 1946 A
3467041 Greulich Sep 1969 A
4037549 Hanyu et al. Jul 1977 A
4193361 Johnson Mar 1980 A
4353857 Ray et al. Oct 1982 A
4628845 Matsuda Dec 1986 A
5566707 Ching et al. Oct 1996 A
Foreign Referenced Citations (1)
Number Date Country
11-137880 May 1999 JP