Patent Application
20060150877
The disclosure relates to a horizontal rotary hook for a sewing machine which includes an inner bobbin-case holder for accommodating a bobbin and an outer rotating hook which has a beak and accommodates the bobbin case holder, and more particularly to such a horizontal rotary hook for a sewing machine in which the beak is a component separated from the rotating hook.
A horizontal rotary hook providing an easy replacement of a bobbin has conventionally been used in sewing machines. The horizontal rotary hook comprises an outer rotating hook formed with a lace and an inner bobbin case holder which accommodates a bobbin and is held so as to be rotatable relative to the lace face. The rotating hook is adapted to be rotated in a predetermined direction by a sewing machine motor or the like.
The bobbin case holder is made of a synthetic resin so that a reduction is achieved in the weight and production cost thereof. Furthermore, the rotating hook has also been made of a synthetic resin recently. In this case, a beak is provided on an outer peripheral wall of the rotating hook for seizing a loop of bobbin thread. However, when the beak is formed integrally on the rotating hook, the structure of a forming die used for forming the rotating hook is complicated. Furthermore, the beak necessitates a higher strength than the other part of the rotating hook. In view of these problems, a beak member provided with a beak has been proposed to be formed separately from the rotating hook and mounted on the rotating hook. For example, JP-U-S60-149388 discloses a horizontal rotary hook in which a beak is made of a metal and mounted on an inner peripheral surface of an outer peripheral wall of the hook so as to be laid on the inner peripheral surface.
However, a thickness of a part of the rotating hook on which the beak member is laid is increased when the beak member is mounted inside the outer peripheral wall of the rotating hook. Consequently, the size of the horizontal rotary hook is increased.
In order that the increase in the size of the overall horizontal rotary hook may be limited, the beak member is suggested to be disposed in an opening formed by cutting out the outer peripheral wall of the horizontal rotary hook and mounted to the bottom of the rotating hook by screws so as to joined to the rotating hook. However, when the beak member is simply mounted to the bottom of the rotating hook made of the synthetic resin, a sewing thread is entangled in a space defined between the inner rotating hook and the beak member. Upon occurrence of such thread entanglement, the beak member is instantaneously subjected to a large external stress traveling outward. As a result, the beak member is deformed or a part of the beak member mounted to the outer rotating hook is damaged.
Therefore, an object of the disclosure is to provide a horizontal rotary hook for a sewing machine, in which a beak member separate from the outer rotating hook can be mounted on the rotating hook reliably and rigidly while the thickness of the outer peripheral wall of the rotating hook is prevented from being increased.
In one aspect, the disclosure provides a horizontal rotary hook for a sewing machine, which includes an inner bobbin case holder accommodating a bobbin therein and an outer rotating hook accommodating the bobbin case holder and rotated in a predetermined direction with the bobbin case holder being accommodated in the rotating hook, the rotating hook having an outer peripheral wall formed with a bobbin-thread passing opening through which the bobbin thread passes, the horizontal rotary hook comprising an enlarged opening defined in the outer peripheral wall of the rotating hook so as to be continuous to the bobbin-thread passing opening, a beak member separate from the rotating hook and mounted on the rotating hook so as to close the enlarged opening, and a fitting holder provided on the rotating hook so that a lower part of the beak member is fitted thereinto, thereby holding the beak member.
According to the above-described aspect of the disclosure, the beak member is mounted on the rotating hook so as to close the enlarged opening. Accordingly, since the beak member is prevented from being laid on the outer peripheral wall of the rotating hook, the thickness of the outer peripheral wall of the rotating hook and accordingly, the entire size of the horizontal rotary hook can be prevented from being increased. Further, since the beak member is held by the holder while being fitted therein, the beak member can be mounted on the rotating hook reliably and firmly. Additionally, only the beak member needs to be replaced even when the loop seizing beak has broken. Consequently, the replacement of the beak member can render the repair cost lower than the replacement of the entire rotating hook.
In one embodiment of the disclosure, the beak member has an outer surface, the rotating hook has a bottom, and the fitting holder is formed so as to protrude outward from the outer peripheral wall of the rotating hook and has a reinforcing peripheral wall continuous to the outer peripheral wall of the rotating hook and supporting the outer surface of the beak member and a reinforcing bottom continuous to the bottom of the rotating hook. Consequently, even if thread entanglement causes the beak member to be subjected to an outgoing force, the outer surface side of the beak member can be received and supported by the reinforcing peripheral wall, whereupon the mounting strength of the beak member against an outward stress can be improved.
In another embodiment of the disclosure, the beak member is made of a synthetic resin and as a result, the production cost can be reduced. When both beak member and outer rotating hook are made of a synthetic resin, different materials can be used so that the material for the beak member has a higher hardness. Consequently, the strength of the beak member can be improved.
Other objects, features and advantages of the disclosure will become clear upon reviewing the following description of the illustrative aspects with reference to the accompanying drawings, in which:
An embodiment of the invention will be described with reference to the accompanying drawings. In the embodiment, the invention is applied to a horizontal full rotary hook in which an outer rotating hook is rotated continuously in one direction. Referring first to
A cloth feed mechanism (not shown) is provided inside the bed 52 for driving the feed dog in synchronization with the vertical movement of the needle bar 55. Further, a horizontal full rotary hook 1 of the embodiment is located below the bobbin-accommodating hole 57. The horizontal full rotary hook 1 includes a beak member 5 and an outer rotating hook 3 (see
In the sewing machine thus constructed, when the rotating hook 3 is rotated counterclockwise in synchronization with the vertical movement of the needle bar 55, a loop of needle thread (not shown) formed by a sewing needle 54 below an eye 56a of the sewing needle is caught by a loop seizing beak member 5. This direction of rotation will hereinafter be referred to as “hook rotating direction A.” The thread loop is then entangled with the bobbin thread 59 while being passed outside the bobbin case holder 2, whereby a stitch is formed.
The horizontal full rotary hook 1 will now be described in detail with reference to FIGS. 2 to 12. The bobbin case holder 2 will first be described. Referring to
Referring to
Next, the rotating hook 3 will be described. Referring to
The hook body 4 has a disc-shaped bottom 21 and an outer circumferential wall 20 which is formed integrally with the bottom so as to rise from an outer circumference of the bottom. The hook body 4 has a slightly larger diameter than the bobbin case holder 2. The hook body 4 includes a part formed into a needle thread passing opening 22 through which a needle thread caught by the beak member 5 passes, as shown in FIGS. 5 to 7. The wall 20 is further formed with an enlarged opening 23 (see
Referring now to
The beak member 5 is a component separate from the hook body 4 and is detachably attached to the hook body 4 in the embodiment. A mounting structure for the beak member 5 will be described in detail. The construction of the beak member 5 will firstly be described. The beak member 5 has a height equal to that of the outer circumferential wall 20 and is formed into the shape of a plate curved at the same curvature as the wall 20 as viewed from above, as shown in
The beak peripheral wall 32 has an upper face including a forward side with respect to a rotation direction A of the rotating hook as shown in
The beak peripheral wall 32 also has an inner periphery including a horizontal thin plate-shaped beak body 33 formed integrally with the wall 32 so as to be located near to the lower side of the lace 24 (the side lower than the chain line K) as shown in
A fixing block 34 is integrally formed on the inner periphery of the support wall 31 as shown in
On the other hand, the hook body 4 is provided with a fitting holder 43 for holding the beak member 5. The fitting holder 43 includes a reinforcing peripheral wall 41 protruding outward from the outer peripheral wall 20 of the hook body 4 and supporting a lower outer face of the beak member 5 as shown in
On the other hand, the reinforcing bottom 40 continuous to the bottom 21 is formed into a generally T-shape as viewed on a plane so as to be located slightly lower than the bottom 21. The reinforcing bottom 40 has a screw hole 40a formed an inner part thereof so that the screw hole 40a corresponds to the screw hole 36a of the fixing block 34 of the beak member 5. The reinforcing bottom 40 further has a circular pin hole 40b for positioning the beak member 5 and an elongate circular pin hole 40c which is slightly longer laterally than the pin hole 40b. The pin holes 40b and 40c are formed so as to correspond to the aforesaid two positioning pins 37 respectively. A small fixing screw 38 is inserted upward through the screw hole 40a to be screwed into the screw hole 36a of the fixing block 34 (see
A plurality of inclined faces 32a, 33a, 20a and 20b are adapted to be formed when the beak member 5 and the rotating hook 5 are injection-molded. More specifically, as shown in
On the other hand, the third inclined face 20a is formed on an edge of the outer peripheral wall 20 fronting to the aforesaid enlarged opening 23 and the beak member 5 as shown in
An operation and effect of the horizontal rotary hook constructed above will now be described. The beak member 5 is mounted on the rotating hook 3 in the manner as described below. Firstly, the beak member 5 is fitted with the fitting holder 43 provided on the rotating hook 3 from above as shown in
The pin hole 40c which is slightly longer laterally than the pin hole 40b. Accordingly, even if the distance between the positioning pins 37 has a dimensional error, the error can be absorbed by the elongate pin hole 40c. Consequently, the beak member 5 can be mounted on the rotating hook 5 reliably and accurately, and productivity and workability can be improved. Furthermore, since the beak member 5 is guided by the reinforcing peripheral wall 41 and inner reinforcing wall 42 onto the reinforcing bottom 40 of the fitting holder 43, the beak member 5 can readily be mounted on the rotating hook 3.
When the beak member 5 is located on the reinforcing bottom 40, the fixing screws 38 of the beak member 5 are screwed into the screw holes 40a and 36a respectively so that the beak member 5 is fixed via the fixing block 34 to the rotating hook 3. Consequently, the beak member 5 is stably fixed to and reliably mounted on the rotating hook 3. Furthermore, the two positioning pins 37 are in engagement with the pin holes 40b and 40c respectively. As a result, even when the beak member 5 is instantaneously subjected to an external stress caused by thread entanglement or the like and acting outward, the strength of the beak member 5 can be increased so as to withstand the stress.
Moreover, in this case, the corner support 41a, reinforcing peripheral wall 41 and inner reinforcing wall 42 are constructed to be caused to abut against the beak member 5, thereby holding the beak member 5 in a vertical position. More specifically, the outer surface of the beak member 5 abuts against the inner surface of the reinforcing peripheral wall 41, and the forward side of the beak member 5 with respect to the rotation direction A of the rotating hook 3 abuts against the corner support 41a from inside. The inner surface of the forward side of the beak member 5 with respect to the rotation direction A of the rotating hook 3 abuts against the inner reinforcing wall 42 from outside. Accordingly, the beak member 5 is reinforced as the result of the abutment against the corner support 41a, reinforcing peripheral wall 41 and inner reinforcing wall 42. Consequently, the strength overcoming the aforesaid external stress can be ensured.
Furthermore, since the beak member 5 is fixed to the rotating hook 3 by the fixing screw 38, only the beak member 5 can easily be replaced as occasion demands. As a result, the replacement can render the replacement cost lower than the replacement of the whole rotating hook 3. Since a synthetic resin is employed as the material for the beak member 5, the beak member can readily be formed into a product. The synthetic resin can reduce the production cost of the beak member 5 as compared with the beak member is made of a metal. More specifically, since the rotating hook 3 is made of a nylon resin and the beak member 5 is made of a polyimide resin having a higher hardness than the nylon resin, a sufficient hardness can be ensured for the beak member 5. Additionally, the production cost can be reduced in this case as compared with the case where the whole rotating hook 3 is made of the polyimide resin.
Furthermore, the enlarged opening 23 is formed so as to be continuous to the needle-thread passing opening 22. The beak member 5 is mounted on the rotating hook 3 so as to close the enlarged opening 23. Accordingly, the thickness of the outer peripheral wall 20 need not be increased. Thus, the beak member 5 and the rotating hook 3 can be composed as discrete components while the size of the rotating hook 3 is prevented from being increased. Furthermore, even when the beak member 5 and the rotating hook 3 are separate from each other, the outer peripheral wall 20 of the rotating hook 3 can be extended by the beak peripheral wall 32, whereupon the needle thread can reliably be captured. Additionally, the beak body 33 is formed so as to extend toward the forward side by the predetermined dimension and so as to protrude inward. Consequently, the needle thread can be captured more effectively and more reliably.
In a sewing operation, the rotating hook 3 is rotated in the rotation direction A by a hook driving mechanism (not shown) such that the bobbin case holder 2 is rotated relative to the rotating hook 3 while being supported on the lace 24 (see
The beak peripheral wall 32 is located outside the lace 24 of the rotating hook 3 (outside the chain line K) and is continuous to the outer peripheral wall 20. Consequently, the bobbin case holder 2 can smoothly be rotated without interference with the beak peripheral wall 32.
The thread guide 13 of the bobbin case holder 2 is prevented from colliding with the beak peripheral wall 32 and beak body 33 when passing over the beak body 33. More specifically, the beak peripheral wall 32 is formed with the first inclined face 32a and the beak body 33 is formed with the second inclined face 33a. Each inclined face is located at the forward side of the beak member 5 with respect to the rotation direction A of the rotating hook 3. Since the thread guide 13 is guided by the inclined faces 32a and 33a, the thread guide 13 of the bobbin case holder 2 can smoothly pass over the beak member 5.
Furthermore, the thread guide 13 can be prevented from colliding with the forward side edge of the outer peripheral wall 20 when passing the forward side edge of the outer peripheral wall 20. More specifically, the forward side edge of the outer peripheral wall 20 is formed with the third and fourth inclined faces 20a and 20b both located at the forward side with respect to the rotation direction A of the rotating hook 3. Since the thread guide 13 is guided by the third and fourth inclined faces 20a and 20b, the thread guide 13 can smoothly pass the forward edge of the outer peripheral wall 20.
Several modified forms of the foregoing embodiment will now be described. The beak member 5 may be made of a metal, instead. Three or more positioning pins 37 may be formed on the beak member 5. Also, three or more pin holes may be formed in the reinforcing bottom 40. When a sufficient space is allowed to be provided around the rotating hook 3, the reinforcing peripheral wall 41 may have a height increased up to about a half of a height of the outer peripheral wall 20. In this case, the reinforcement strength of the beak member 5 can further be improved.
The foregoing description and drawings are merely illustrative of the principles of the present invention and are not to be construed in a limiting sense. Various changes and modifications will become apparent to those of ordinary skill in the art. All such changes and modifications are seen to fall within the scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-338541 | Nov 2004 | JP | national |
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-338541, filed on Nov. 24, 2004, the entire contents of which are incorporated herein by reference.
