Slide drive unit of a press

Information

  • Patent Grant
  • 6595125
  • Patent Number
    6,595,125
  • Date Filed
    Tuesday, April 23, 2002
    22 years ago
  • Date Issued
    Tuesday, July 22, 2003
    20 years ago
Abstract
Angle (θ) formed by straight lines (A, B) connecting a fixed shaft (23) and two connecting shafts (24, 25) of a triaxial link (16) of a slide drive unit (10) is set acute, so that position of a slide at any crank angle can be made higher than a conventional arrangement throughout the entire slide motion and the slide can be located above a height necessary for conveying a workpiece for a longer time per the same cycle speed, thereby driving a transfer feeder with sufficient time, allowing secure conveyance of the workpiece while improving productivity of a press and avoiding restriction of design.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a slide drive unit of a press, which more specifically relates to a slide drive unit with improved slide motion.




2. Description of Related Art




Conventionally, a slide drive unit of a link press slowly lowers and quickly raises a slide, an example of which has been shown in Japanese Examined Patent Publication No. Sho 47-7835.




The slide drive unit has: a main gear rotated around a main gear supporting fixed shaft; a double-arm link and a single-arm link rotatably fitted to an eccentric drum integrated with the main gear; a connecting rod connected to an end of the double-arm link; an intermediate link connected to the other end of the double-arm link; and a triaxial link rotated around another fixed shaft parallel to the main gear supporting fixed shaft and connected to the intermediate link and the single-arm link, the fixed shaft and the other two shafts (connected with the intermediate link and the single-arm link) of the triaxial link being located approximately on a straight line extending approximately perpendicular with the fixed shaft at the center thereof.




Since deep-drawing formability is attached so much importance in the slide drive unit that slide motion in lowering the slide becomes too gentle, the difference between crank angle where the slide is located at a height above the bottom dead center and crank angle at the bottom dead center is substantially great. Accordingly, the slide reaches at a low position at an early stage before the bottom dead center.




Incidentally, a transfer press is ordinarily continuously driven without stopping at the top dead center per one operation cycle as in a single press and a tandem press, and SPM (cycle per a minute) tends to increase for improving productivity, where the time per one cycle may be two to three seconds.




When the above-described slide drive unit is applied to the transfer press, since the slide reaches to the low position at a too early stage, the time reserved for conveyance of a workpiece with a transfer bar is further shortened and feed motion of the transfer bar is strictly limited. Accordingly, high-speed drive of the transfer feeder is required.




However, when the transfer feeder is driven at a high speed without changing the feed motion, great acceleration and deceleration is applied on the transfer bar, thereby easily causing misfeed of a workpiece. Therefore, there is inherent limit for increasing the speed of the transfer feeder. Though a workpiece may be securely conveyed while causing small acceleration and deceleration on the transfer bar by adjusting the feed motion, the conveyed workpiece is likely to interfere with the die in this arrangement, so that die design becomes difficult.




In order to reduce acceleration and deceleration generated on the transfer bar while overcoming the restriction on the die to improve the productivity of a press, longer time has to be retained for conveying the workpiece, and slide motion therefor has been desired.




SUMMARY OF THE INVENTION




An object of the present invention is to achieve a slide motion of a slide drive unit of a press capable of improving the productivity of a press and prolonging the time for conveying a workpiece.




A slide drive unit of a press according to an aspect of the present invention includes: a main gear; a double-arm link and a single-arm link rotatably fitted to an eccentric drum integrated with the main gear; a connecting rod connected to one end of the double-arm link; an intermediate link connected to the other end of the double-arm link; and a triaxial link rotated around a fixed shaft parallel to a main gear supporting fixed shaft for supporting the main gear, the triaxial link being connected with the intermediate link and the single-arm link, in which an angle formed by a straight line connecting a connecting shaft of the intermediate link with the fixed shaft of the triaxial link and another straight line connecting the connecting shaft of the single-arm link and the triaxial link and the fixed shaft of the triaxial link is acute.




According to the above aspect of the present invention, the angle formed by straight lines connecting a fixed shaft and two connecting shafts of a triaxial link is set acute, so that position of a slide at any crank angle can be made higher than a conventional arrangement throughout the entire slide motion, where the time for, for instance, the slide to be lowered from the top dead center to a predetermined position can be lengthened. Accordingly, the slide can be located above a height necessary for conveying a workpiece for a longer time per the same SPM, thereby driving a transfer feeder with sufficient time. Therefore, the workpiece can be securely conveyed without causing great acceleration and deceleration to a transfer bar etc. and restricting die design even when the productivity of the press is enhanced.




In the above arrangement, one end of the connecting rod may preferably be connected to the double-arm link and the other end of the connecting rod may preferably be connected to the slide or a plunger perpendicularly reciprocating between the connecting rod and the slide, and wherein horizontal position of a center of a shaft connecting the other end of the connecting rod may preferably be shifted to a side opposite to the fixed shaft of the triaxial link relative to a shaft center of the main gear supporting fixed shaft. With the above arrangement, only compressive force is applied to the single-arm link or the intermediate link while driving the slide, so that shaky movement at the connecting shaft of the respective links caused by switching force such as alternately applied compressive force and tensile force is unlikely to be caused, thereby improving processing accuracy.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front elevational view schematically showing a press applied with a slide drive unit according to an embodiment of the present invention;





FIG. 2

is an entire perspective view showing the slide drive unit according to the aforesaid embodiment;





FIG. 3

is a front elevational view enlarging the slide drive unit according to the aforesaid embodiment when a slide is located at a bottom dead center;





FIG. 4

is a cross section showing a slide drive unit according to the aforesaid embodiment; and





FIG. 5

is a graph showing a slide motion of the slide drive unit of the aforesaid embodiment.











DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)




An embodiment of the present invention will be described below with reference to attached drawings.





FIG. 1

is a front elevational view showing a press


1


applied with a slide drive unit


10


(


10


A,


10


B) according to the present embodiment,

FIG. 2

is an entire perspective view represented by a slide drive unit


10


A,

FIG. 3

is a front elevational view showing a slide drive unit


10


A when a slide (not shown) is at a bottom dead center in an enlarged manner, and

FIG. 4

is a cross section of the slide drive unit


10


A.




In

FIG. 1

, the press


1


constitutes a part of a transfer press having a plurality of processing stations. The press


1


has a crown


2


accommodating two slide drive units


10


(


10


A,


10


B), a slide


3


connected to the slide drive unit


10


through a plunger


3


A and attached with an upper die, a bed (not shown) provided with an accommodatable moving bolster


4


A for a lower die to be attached, and an upright


5


for connecting the bed and the crown


2


.




Incidentally, an ordinary bolster fixed to a bed may be used instead of the moving bolster


4


A and the slide drive unit


10


and the slide


3


may be directly connected without using the plunger


3


A.




The slide drive unit


10


of transfer press includes a slide drive unit


10


A of greater capacity and a slide drive unit


10


B of smaller capacity.




The slide drive unit


10


A is driven by a drive force transferred from a main motor (not shown) through a flywheel


6


and gears


7


A and


7


B. The slide drive unit


10


B is driven by drive force transferred from the main motor through the flywheel


6


and gears


7


A,


7


C and


7


D, the main gears


11


of the slide drive unit


10


A and


10


B being rotated in mutually reverse manner.




Ordinarily, the slide drive unit


10


A of greater capacity is located on an upstream in a direction for a workpiece to be conveyed (left side in FIG.


1


), and the slide drive unit


10


B of smaller capacity is located on a downstream in a direction for a workpiece to be conveyed (right side in

FIG. 1

) in approximately symmetric manner. However, the two slide drive units


10


A and


10


B may have the same capacity.




The slide drive unit


10


A will be specifically described below. Since the slide drive unit


10


B has the same structure and can be understood by the description of the slide drive unit


10


A, the same reference number used for the components of the slide drive unit


10


A will be attached to the slide drive unit


10


B (FIG.


1


), and detailed description will be omitted.




In

FIGS. 1

to


5


, the slide drive unit


10


A is a device having so-called link mechanism, which includes a main gear


11


rotatably supported by a main gear supporting fixed shaft


20


and meshing with the gear


7


A for the drive force from the main motor to be transferred.




Incidentally, the gear portion of the main gear


11


is omitted in

FIGS. 2 and 3

.




Eccentric drums


11


A are respectively provided on both sides of the main gear


11


and a double-arm link


12


is rotatably fitted to an outer circumference of the eccentric drum


11


A. Similarly, a single-arm link


13


is rotatably fitted to the outer circumference of the respective eccentric drums


11


A to be located on an inside of the double-arm link


12


. A connecting rod


14


is connected to a lower side of the respective double-arm link


12


through a connecting shaft


21


and an intermediate link


15


is connected to an upper end of the double-arm link


12


through a connecting shaft


22


.




The intermediate link


15


and the single-arm link


13


are connected to a triaxial link


16


rotated around a fixed shaft


23


parallel to the main gear supporting fixed shaft


20


through connecting shafts


24


and


25


. The fixed shaft


23


is located opposite to the slide drive unit


10


B relative to the main gear supporting fixed shaft


20


.




The plunger


3


A is connected to the lower end of two connecting rods


14


through a connecting shaft


26


and a slide


3


(

FIG. 1

) is connected to the lower side of the respective plungers


3


A. In other words, the press of the present embodiment is of a four-connecting-point type of which slide


3


is connected with total four plungers


3


A of the respective slide drive units


10


A and


10


B. The respective plungers


3


A reciprocally move inside a plunger guide


3


B (only one is shown in

FIG. 2

) in perpendicular direction between the connecting rod


14


and the slide


3


.




The triaxial link


16


includes a triangle first link member


16


A to which the fixed shaft


23


and the connecting shafts


24


and


25


are inserted, an outside second link member


16


B to which the fixed shaft


23


and the connecting shaft


24


are inserted, and an inside third link member


16


C for the fixed shaft


23


and the connecting shaft


25


are inserted, a part of the triaxial link


16


being accommodated in a projecting part


2


A projecting from a side of the crown


2


(FIG.


1


).




In the triaxial link


16


, angle θ formed by a straight line A connecting respective centers of the fixed shaft


23


and the connecting shaft


24


and a straight line B connecting respective centers of the fixed shaft


23


and the connecting shaft


25


is an acute angle smaller than ninety degrees. Especially, when the slide


3


is at the bottom dead center thereof, the shaft center of the connecting shaft


24


is located below the shaft center of the fixed shaft


23


and on the side of the main gear supporting fixed shaft


20


, and the shaft center of the connecting shaft


25


is located below the shaft center of the fixed shaft


23


and on the side of the main gear supporting fixed shaft


20


and opposite to the main gear supporting fixed shaft


20


relative to the connecting shaft


24


(on the side of the fixed shaft


23


).




The shaft center of the connecting shaft


26


connecting the connecting rod


14


and the plunger


3


A is horizontally shifted relative to the shaft center of the main gear supporting fixed shaft


20


by an offset C and is located opposite to the fixed shaft


23


. The offset C is set so that a locus D of a shaft center of the connecting shaft


21


connecting the double-arm link


12


and the connecting rod


14


is always drawn on one side relative to the shaft center of the main gear supporting fixed shaft


20


, i.e. on the opposite side of the fixed shaft


23


. Accordingly, the force applied to the single-arm link and the intermediate link


15


is 5 to 10% of connecting point capacity (tonnage) and is restricted only to compressive force.




The slide motion of the slide drive unit


10


arranged above is shown in solid line in FIG.


5


. In

FIG. 5

, horizontal axis represents crank angle and vertical axis represents the height from the bottom dead center of the slide


3


. The dotted line represents the slide motion of the conventional slide drive unit described in the background art section.




As shown in

FIG. 5

, according to the slide drive unit


10


of the present embodiment, the slide position at the crank angle of ninety degrees in lowering the slide


3


is Y


1


. On the contrary, the slide position of the conventional slide unit is Y


2


, showing that the position is higher in the slide drive unit


10


by ΔY at the same crank angle, which also holds true from the start of lowering to the bottom dead center. Further, the solid line is above the dotted line after the slide


3


passes the bottom dead center and starts moving upward, which shows that the slide position is higher at the same crank angle than the conventional arrangement.




When the slide position is higher for the same crank angle, the time capable for being reserved for conveyance of workpiece can be lengthened. For instance, when the height necessary for conveying the workpiece is assumed Y


2


, though the workpiece cannot be conveyed at the crank angle ninety degrees in the conventional slide drive unit in lowering the slide, the workpiece can be conveyed until the crank is rotated to the angle θ


1


in the slide drive unit of the present embodiment. Further, in raising the slide, though the workpiece cannot be conveyed until the crank angle reaches θ


3


in the conventional slide drive unit, the workpiece can be conveyed from the crank angle θ


2


in the slide drive unit of the present embodiment. Accordingly, the slide drive unit of the present embodiment can lengthen the time reserved for conveyance of the workpiece as compared to the conventional slide drive unit.




According to the present embodiment, following advantages can be obtained.




(1) Since the angle θ formed by the straight lines A and B connecting the fixed shaft


23


and the two connecting shafts


24


and


25


of the triaxial link


16


is set acute in the slide drive unit


10


, the position of the slide


3


for the same crank angle is higher than the conventional arrangement until the slide


3


moves from the top dead center to the bottom dead center, so that the time for the slide


3


to reach a predetermined position, i.e. the time for the slide


3


to be lowered to a height where conveyance of the workpiece becomes difficult, becomes longer than the conventional arrangement at the same SPM, thereby allowing the transfer feeder to be driven with sufficient time. Accordingly, even when SPM of the press is raised to improve the productivity, the workpiece can be securely conveyed without causing great acceleration and deceleration on the transfer bar or strictly limiting the design of die configuration.




(2) Further, as shown in

FIG. 5

, since the slide


3


is raised earlier than the conventional arrangement after raising the slide


3


, the workpiece can be transferred from a processing station at earlier timing. Accordingly, the transfer feeder can be driven with sufficient time, and the transfer feeder can easily follow increase in SPM of the press


1


, productivity can be improved.




(3) Since the shaft center of the connecting shaft


26


connecting the connecting rod


14


and the plunger


3


A of the slide drive unit


10


is shifted by offset C relative to the shaft center of the main gear supporting fixed shaft


20


and the locus D of the shaft center of the connecting shaft


21


connecting the double-arm link


12


and the connecting rod


14


is always drawn on the side opposite to the fixed shaft


23


relative to the shaft center of the main gear supporting fixed shaft


20


, only compressive force can be constantly applied to the single-arm link


13


and the intermediate link


15


, thereby preventing tension force and compressive force from being alternately applied. Accordingly, shaky movement of the single-arm link


13


and the intermediate link


15


is unlikely while driving the slide drive unit


10


, thereby obtaining highly accurate molding.




(4) Since the compressive force applied to the single-arm link


13


and the intermediate link


15


can be substantially reduced by the arrangement of (3), the thickness of the single-arm link


13


and the intermediate link


15


can be reduced, thereby reducing the size and weight of the link member.




(5) Since the angle θ formed by the straight lines A and B of the triaxial link


16


is acute, the dimension between the connecting shafts


24


and


25


can be reduced, so that vertical dimension of the entire triaxial link


16


can be reduced, thereby further enhancing reduction in size and weight of the link member.




Since the size of the triaxial link is reduced, only the projecting part


2


A is provided on a side of the crown


2


and the length of the body of the crown


2


is not necessarily be extended on the entire height as in the conventional link mechanism, so that the weight of the body of the crown


2


can be substantially reduced.




Incidentally, the scope of the present invention is not restricted to the above-described embodiments.




For instance, though the shaft center of the connecting shaft


26


is shifted by offset C relative to the shaft center of the main gear supporting fixed shaft


20


, the offset may be zero and there may be no shift between the shaft centers in the present invention. However, since the above advantages of (3) and (4) can be obtained by setting the offset C, the shaft centers may preferably be offset.




In the triaxial link


16


of the present embodiment, though the shaft center of the connecting shaft


24


is below the shaft center of the fixed shaft


23


and on the side of the main gear supporting fixed shaft


20


and the shaft center of the connecting shaft


25


is below the shaft center of the fixed shaft


23


and on the side of the main gear supporting fixed shaft


20


and on the side of the fixed shaft


23


relative to the connecting shaft


24


, the connecting shaft


24


may be located approximately at the same height as the fixed shaft


23


or may be located slightly above the fixed shaft


23


. In other words, the present invention only requires that the angle θ formed by the straight lines A and B connecting the fixed shaft


23


and the connecting shafts


24


and


25


is acute and the positional relationship between the fixed shaft


23


and the connecting shafts


24


and


25


may be changed in implementing the present invention.




Though the press


1


of the above-described embodiment is four-connecting-point type which includes two slide drive units


10


(


10


A and


10


B) and four plungers


3


A, the motion or number of the connecting-points is not limited to the above-described embodiment but may be set as desired considering the capacity of the press to which the present invention is applied. However, since the respective slide drive units


10


A and


10


B are approximately symmetrically located as in the present embodiment, sufficient durability can be obtained in a transfer press to which biased load is easily applied in processing.




Further, though the slide position at the same crank angle is higher than the conventional arrangement not only in lowering the slide


3


but also in raising the slide


3


, approximately the same slide motion may be conducted in raising the slide


3


in the present invention.




The configuration etc. of the respective link member constituting the slide drive unit may be designed at will in implementing the present invention, which is not restricted to the above specific embodiments.



Claims
  • 1. A slide drive unit of a press, comprising:a main gear (11); a main gear supporting fixed shaft (20) for the main gear to be supported; a double-arm link (12) and a single-arm link (13) rotatably fitted to an eccentric drum (11A) integrated with the main gear (11) of which a rotation center is eccentric relative to the main gear supporting fixed shaft; a connecting rod (14) connected to one end of the double-arm link (12); an intermediate link (15) connected to the other end of the double-arm link (12); and a triaxial link (16) rotated around a fixed shaft (23) parallel to the main gear supporting fixed shaft (20), the triaxial link being connected with the intermediate link (15) and the single-arm link (13), wherein an angle (θ) formed by a straight line (A) connecting a connecting shaft (24) of the intermediate link (15) with the fixed shaft (23) of the triaxial link (16) and another straight line (B) connecting a connecting shaft (25) of the single-arm link (13) and the triaxial link (16) and the fixed shaft (23) of the triaxial link (16) is acute.
  • 2. The slide drive unit of a press according to claim 1, wherein one end of the connecting rod (14) is connected to the double-arm link (12) and the other end of the connecting rod (14) is connected to a slide (3) or a plunger (3A) perpendicularly reciprocating between the connecting rod (14) and the slide (3), andwherein horizontal position of a center of a shaft (26) connecting the other end of the connecting rod is shifted to a side opposite to the fixed shaft (23) of the triaxial link (16) relative to a shaft center of the main gear supporting fixed shaft (20).
Priority Claims (1)
Number Date Country Kind
2001-127488 Apr 2001 JP
US Referenced Citations (3)
Number Name Date Kind
2688296 Danly et al. Sep 1954 A
3695090 Kita Oct 1972 A
3772986 Kawagoshi et al. Nov 1973 A
Foreign Referenced Citations (1)
Number Date Country
47-7835 Mar 1972 JP