US3130699A

US3130699A - Double action draw press

Info

Publication number: US3130699A
Application number: US158965A
Authority: US
Inventors: William E Ward
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-12-13
Filing date: 1961-12-13
Publication date: 1964-04-28
Anticipated expiration: 1981-04-28

Description

w. E. WARD 3,130,699

DOUBLE ACTION DRAW PRESS April 28, 1964 Filed Dec. 15, 1961 8 Sheets-Sheet l INVENTOR.

WILLIAM E .WARD

ATTORNEYS April 28, 1964 w. E. WARD 3,130,699

DOUBLE ACTION DRAW PRESS Filed Dec. 15, 1961 8 Sheets-Sheet 2 INVENTOR. WILLIAM E-WARD TORNEYS April 29, 1964 w, E, WARD 3,130,699

DOUBLE ACTION DRAW PRESS Filed Dec. 15, 1961 8 Sheets-Sheet 5 FIG3 INVENTOR. WILLIAM E,WARD

BY W W ATTORN vs April 28, 1964 w. E. WARD DOUBLE ACTION DRAW PRESS Filed Dec. 13, 1961 8 Sheets-Sheet 4 INVENTOR.

E .W ARD WILLIAM FIG T TORNEYS April 28, 1964 w. E. WARD 3,130,699 DOUBLE ACTION DRAW PRESS 8 Sheets-Sheet .5

Filed Dec. 15, 1961 INVENTOR. WILLIAM E.WARO

ATTORNEYS April 28, 1964 w. E. WARD 3,130,699

DOUBLE ACTION DRAW PRESS Filed Dec. 13, 1961 8 Sheets-Sheet 6 INVENTOR.

WILLIAM E.WI \RD BY ATTORNEYS April 28, 1964 w. E. WARD DOUBLE ACTION DRAW PRESS 8 Sheets-Sheet 7 Filed Dec. 13, 1961 0 2O 4O 60 80 I00 I20 [40!60 I80 200 220240260280300320 340360 T 33m $2250 865ml FIG ll INVENTOR. WILLIAM EWARD BY @M; WW TTORNEYS A ril 28, 1964 w. E. WARD 3,130,699

' DOUBLE ACTION DRAW PRESS Filed Dec. 15, 1961 8 Sheets-Sheet 8 FIG l2 INVENTOR;

WILLIAM .EWARp TTORNEYS United States Patent 3,130,699 DOUBLE ACTION DRAW PRESS William E. Ward, 3264- Kenmore Road, Shaker Heights, Ohio Filed Dec. 13, 1961, Ser. No. 158,965 13 Claims. (Cl. 113-38) The present invention relates to presses and more particularly to eccentric or crank operated drawing presses having blank holder and die slides reciprocated by crank or eccentric means in such a manner that the blank holder carried by the blank holder slide engages the work blank prior to engagement of the work blank by the die carried by the die slide and dwells or remains in this position to clamp the work blank during the drawing stroke and until the die slide begins its return stroke.

The principal object of the present invention is the provision of a new and improved press having a die slide which is moved at a relatively slow and uniform rate during the working stroke and at a relatively higher rate during the approach and return strokes and wherein the structure which provides such operation is compact and conveniently located preferably in the crown of the press.

Another object of the present invention is the provision of a new and improved drawing press having a blank holder slide actuated to engage a work blank prior to the engagement thereof by the die and to clamp the blank during the drawing operation by a linkage mechanism having fewer working parts than other known linkages of this type and which is simple in construction, reliable in operation, and extremely durable.

Another object of the present invention is the provision of a new and improved press, of the last referred to type, wherein the blank holder slide during the dwell engages the blank at substantially a constant pressure.

The invention resides in certain constructions, combinations, and arrangements of parts and further objects and advantages will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification and in which FIG. 1 is a front elevational view of a press embodying the present invention,

FIG. 2 is a side elevational view of the press shown in FIG. 1,

FIG. 3 is a front view of the press shown in FIG. 1 with certain parts removed and other parts in section,

FIG. 4 is a sectional view of the press shown in FIG. 3 taken approximately along section line 44 thereof with certain parts in elevation,

FIG. 5 is an elevational view of a portion of the press of FIG. 1, illustrating the die slide operating mechanism,

FIG. 6 is a side elevational view of the die slide operating mechanism shown in FIG. 5,

FIG. 7 is an elevational view of the blank holder slide operating mechanism used in the press of FIG. 1,

FIG. 8 is a side elevational view of the blank holder slide operating mechanism shown in FIG. 7,

FIG. 9 is an elevational view of a part of a modified blank holder slide operating mechanism which may be used in the press of FIG. 1,

FIG. 10 is a sectional view taken approximately on section line 10-40 of FIG. 9,

FIG. 11 is a graph illustrating the relative movement of the die slide and blank holder slide of the press of FIG. 1, and

FIG. 12 is a schematic View showing the operating linkage for the blank holder slide of the press of FIG. 1 in different positions.

The invention is susceptible of various modifications and constructions and of use in various types of presses "ice including underdrive presses. For purposes of illustration it is shown embodied in a four-point double action drawing press including a frame of conventional construction having a bed 10, two uprights 11, 12 extending vertically on opposite sides of the bed, and a crown structure 13 secured to the uprights 11, 12 above bed 1%. A rectangular blank holder or hold-down slide 14 is adapted for reciprocable movement between the uprights 11, 12 and is guided by gibs 15 mounted on the uprights 11, 12 and engaging the corners of the slide. The blank holder slide 14 may be of usual construction having a generally rectangular opening therethrough and provided with internal slideways 17 on which a rectangular die slide 18 is adapted to reciprocate relative to the blank holder-slide as is best illustrated in FIG. 4.

The die slide 18 may be of any suitable construction well known in the art and is adapted to have a forming die attachced thereto to cooperate with a die on the press bed 10 to deep draw metal forms from metal blanks. The dies are not shown since they do not form part of the present invention and may be of any desired form, nor are the die cushions or counterbalancing devices shown since they are well known in the art and are not necessary to an understanding of the invention.

The

slides

14, 18 are actuated by means located in the crown 13 in such a manner that the blank holder slide engages the work positioned on the press bed just prior to the commencement of the drawing stroke, i.e. just prior to the engagement of the die on the die slide with the metal blank, and remains in its blank holding position until after the die slide has commenced its return movement to thereby assure stripping of the formed metal from the forming die. The relative movements of the die and blank holder slides are shown by lines A and B, respectively, in FIG. 11. The point :1 represents the beginning of the drawing portion of the die closing stroke when maximum draw is employed, and 1) represents the bottom of the drawing stroke.

The mechanism for operating the

slides

14 and 18 is located in the crown of the press and includes two horizontal shafts 25 fixedly supported in intermediate longitudinal walls 26 in the crown 13. The shafts 25 are positioned transversely of the length of the crown with one shaft 25 on each side of the center of the crown as the press is viewed in FIGS. 1 and 3. A shaft 25 is illustrated in FIG. 4, it being understood that the other shaft 25 is located behind and parallel to the shaft shown. A pair of stud shafts 27 are located in end to end relation with each shaft 25. Specifically, a stud shaft 27 is located at each end of each shaft 25 and is fixedly supported in adjacent wall 26 and the frame of the press. The stud shafts 27 could be formed as integral extensions of the shafts 25, if desired, but are made separate from shafts 25 to facilitate manufacture and assembly of the press.

Each shaft 25 is provided with a pair of bull gears 28 rotatably mounted on the shaft, each bull gear being in mesh with a driving pinion 29. The driving pinions 29 for the pair of gears 28 located on the left side of the press looking at FIG. 3 are mounted on a common transverse shaft 36 in the crown 13 as are the pinions 29 for the pair of gears 28 located on the right side of the press looking at FIG. 3. Each of the shafts 30 for the pinions 29 is driven by a gear 31 mounted thereon, the gears 31 being in mesh with each other so that they rotate in opposite directions. One of the gears 31 is driven by a pinion 32 mounted on a horizontal drive shaft 33 and connected by a suitable clutch mechanism to a flywheel 34 driven by belt drive 35 connected to a suitable motor. The clutch mechanism for connecting the drive shaft 33 to the flywheel 34 is not shown since it can be of any well known construction having control means to effect a single r0- tation of the bull gears 28 each time a pedal or other control member is actuated by the press operator. During the operation of the press, the flywheel is rotated continuously by the motor. The shafts 3th for the pinions 29 and the shaft 33 are suitably journaled in hearings in the crown structure 13 which for the sake of clarity are not shown since the structure is well known in the art.

The rotation of the bull gears 28 operates the blank holder and die slides through linkages and mechanisms associated with each bull gear 28. T he'mechanisms and linkages associated with each gear 28 are the same and, for the sake of clarity, the following description will be directed toward the mechanism and linkages associated with one of the gears 28, it being understood that there are three others in the illustrated embodiment.

Mounted on the shaft 25 for rotation with the gear 28 is an eccentric means which comprises eccentric 36 preferably formed integral with the bull gear 28. The eccentric 36 has a bell crank or eccentric strap 37 journaled thereon which includes

arms

38, 39. The

arms

38, 39 extend away from the eccentric 36 and define an obtuse angle with respect to each other. The arm 38 which is bifurcated is pivotally attached to a link 40 by a pin 41, and the lower end of link 40 is pivotally attached to the die slide 18 by a pin 42 at a point on a side of the slide adjacent to a corner. As is common practice, an adjusting mechanism 43 is provided in the die slide so that the exact shut height or stroke position required for the various dies employed may be easily obtained. It will be understood that there are four links 49 and that one is connected adjacent to each corner of the die slide.

The strap 37 is mounted to pivot about pin 44 fixedly attached to the inner wall 26 of the crown structure. The arm 39 of the strap 37 is provided with a slot 45 through the center line of the arm 39, which line extends through the center of the eccentric. A block or bearing 46 is pivotally journaled on the pin 44 and is positioned in the slot 45.

It is apparent from the above description that when the eccentric 36 is rotated by the gear 28, the block 46 causes the arm 39 of strap 37 to oscillate. This movement causes the toggle joint comprising pin 41 to move through closed elliptical path 49 shown in FIG. 5, thereby causing the die slide 18 to move at a relatively slow and uniform speed through or during the drawing or working stroke and to move at a higher speed during the remainder of its cycle of operation, as is illustrated in the graph shown in FIG. 11. The path 49 is an elongated loop defined by the movement of the pivoted connection of the arm 38 and the link 40 and has its length generally transverse to the line of movement of the lower end of the link 43. The excursion of the pivotal connection to one side of this line is greater than its excursion to the other side of the line. Referring to the graph in FIG. 11, it can be seen that this mechanism causes the approach stroke to occur during approximately 80 of rotation of the eccentric 36, the work or drawing stroke to occur during approximately 120 of rotation of the eccentric 36 and the return stroke to occur during approximately 160 of rotation of the eccentric.

The blank holder slide 14 is actuated in timed relation to the movement of die slide 18 by four links 56, each one being pivotally connected adjacent to one corner of the slide by pins 51 supported in the yoke 52 of a con Ventional screw type adjusting device 53 attached to the slide 14 so that the slide can be adjusted relative to the links 50 to obtain the desired shut height for the blank holder slide. The upper end of the links 50 are attached to individual rocker members 54 which are pivotally mounted on the shafts 27 mounted in the frame. Each of the rocker members 54 includes bifurcated

arms

56, 57 which are oifset from one another, as seen in FIG. 8, and which form an obtuse angle with respect to each other, as shown in FIG. 7. The link 59 associated with each rocker member 54 is pivotally connected to the arm 56 of the rocker member by a pin 58. The end of each of the arms 57 which is remote from the shaft 27 upon which it is supported is pivotally connected to one end of a link 61 by a pivot means including pin 62 which is secured to arm 57. The other end of each of the links 61 is pivotally connected by a pivot means including pin 64 to a support arm 65 formed integral with the eccentric strap 37 and which extends through an opening 66 in the adjacent wall 26 of the crown structure.

Different positions of the blank holder slide 14 and the relative positions of its actuating mechanism during a reciprocation of the blank holder slide is illustrated in FIG. 12. The different parts or elements of the actuating mechanism illustrated are indicated by the corresponding reference characters having suffixes applied to indicate the diiferent positions of the elements for the corresponding different positions of the blank holder slide. The position of the elements are shown in full lines when the blank holding slide is in its raised or rest position and in dotted lines when in its down or blank holding position. As shown in FIG. 12, as the eccentric 36 rotates, the pin 64 which connects the link 61 to the eccentric strap 37 moves through a path defined as a closed loop 71, and the pin 62 which connects the other end of link 61 to the rocker member arm 57 moves through an arcuate path designated '72. The pin 58 which pivotally connects the link 59 to the rocker member arm 56 moves through the arcuate path designated 73, and the pin 51 which connects link 55 to the blank. holder slide moves through a vertical path on line 74. When the blank holder slide is in its topmost vertical position the center of the eccentric is at point 36a, the pin 64- will be located in its path of movement at point 64a, the pin 62 will be located in its path of movement at 62a, and the pin 58 and the pin 51 will be located at points 53a and 51a, respectively, in their paths of movement. Rotation of the eccentric 36 to point 361) causes the pin 64 carried by the eccentric strap 37 to move from point 64a to point 64b which, in turn, through the link 61 moves the pin 62 along its arcuate path 72 to point 62b. This causes pin 53 to move along its arcuate path 73 to point 58b and pin 51 to move vertically on line 74 to its down position designated 51b, at which time the blank holder engages the blank.

Further rotation of the eccentric 36 to point 360 causes the pin 64 to move to point 640, the pin 62 to move to point 620 and pin 58 to move to point 58c. This movement causes the pin 58 to move from the right side of line 74 to the left side thereof as viewed in FIG. 12 even though the blank holder slide is in engagement with the blank because of the flexibility of the parts of the press and the fact that the pin 5% at this time is moving substantially at right angles to the line 74. During this movement of the pin 58 from the point 58]) to the point 580 the blank holder slide is in its down or clamping position and does not move. As the eccentric 36 continues to rotate to point 36d the pin 64 moves from point Me to 64d. This movement produces only a small amount of movement of the pin 62, moving it back to point 62b, concurrently the pin 58 moves back to point 53b, which is on the right side of the line 74 as viewed in FIG. 12. This movement does not move the blank holder slide out of engagement with the blank and the slide remains in its dwell position. The blank holder slide remains in its dwell position during the rotation of the eccentric from the point 36b to the point 36d partly because a portion of the path of movement of the pin 64 from point 640 to 6411 is along an are having a radius approximating the length of the link 61 and the center of which is the pin 62 which moves merely the short distance from the point 62c to 62b. Thus, the link 61 merely pivots about pin 62 and does not cause the pin 62 to move any substantial amount, with the result that the

pins

58 and 51 will be held substantially stationary. This causes the blank slide to remain in its down position without any substantial change in the pressure between the blank slide and the blank.

The pin 58, as it moves along the portion of path 73 between points 58b and 580 and then back to point 58b, maintains the blank holder slide in its dwell position in engagement with the blank, as aforementioned. Movement of the pin 58 in this portion of its path does not result in any substantial change in the pressure exerted by the blank holder slide on the blank. This is true whether the pin 58 which moves the blank holder slide is completing its arcuate movement toward the left as viewed in FIG. 12 and passes from the right side of line 74 to the left side, as viewed in FIG. 12, or whether the pin 58 is beginning its return movement toward the right as viewed in FIG. 12 and is moving from the left side of line 74 to the right side thereof.

In order to insure that the blank holder slide engages the blank with a substantially constant pressure, either or both ends of the link 61 may be connected to the

pins

64 and 62 by yieldable means. The yieldable means may be constructed in different ways and may include yieldable

material encircling pins

62, 64 or partially encircling the

pins

62, 64. An example of this alternate construction is shown in FIGS. 9 and 10. As shown in these figures, opposite ends of the link 61 are provided with yieldable means 80, 81, each of which includes a metal bushing 82 encircling the

pins

62, 64 and a resilient material 83, which conveniently may be rubber, located around a portion of the bushing 82 and between the bushing 32 and link 61. Specifically, the resilient material 83 of each yieldable means 30, S1 is in the form of one-half of a cylinder wall and each of these cylinder walls is located encircling one-half of one of the bushings 82, as shown in FIGS. 9 and 10. The portions of bushings 82 encircled by the resilient material 83 are the portions located above a line through the centers of the

pins

62, 64 and which line is perpendicular to a line connecting the centers of

pins

62, 64. Spacer means 34 are provided at the circumferential edges of the resilient material 83. The spacer means 84 extend the length of bushings 82 and are provided with grooves 85 positioned so that the resilient material 83 upon compression can expand into the grooves 85.

It should be apparent that the yieldable means S6, 81 will insure that the blank holder slide maintains a substantially constant pressure on the blank. When the blank holder slide engages the blank upon reaching point 5812 the pin 64 is at point 64b and pin 62 is at point 62b and moving towards the right, as viewed in FIG. 12, thereby tending to force the blank holder slide downwardly. Since the blank holder slide is in engagement with the blank, the force of the link 61 tending to move the pin 62 toward the right will cause the link 61 to compress the resilient material 83 around the pin 62. This compression causes the resilient material 83 to flow into the grooves 85 provided for this purpose, which in turn permits the link 61 to move relative to the pin 62 and the arm 57 and eccentric 36. Subsequently, the force of the link 61 tending to move the pin 62 toward the left will cause the link 61 to compress the resilient material 83 around pin 64. When pin 62 begins to move the compression forces on the material 83 around pins 62, 64 are released and the link 61 returns to its normal position in which it does not compress the material 33. Thus, pin 58 will remain substantially stationary between points 58b and 580 through the entire dwell period, depending upon the amount of resiliency of the material 83 and the resistance encountered by the blank holder slide. Further rotation of the eccentric will cause the press to operate in the same manner as the press shown in FIG. 1 without the resilient material.

While the present invention has been illustrated as embodied in a four point press, it will be readily apparent to those skilled in the art that it is suitable for use in a single point or other type press, and it is to be understood that other forms, adaptations and constructions could be employed which fall within the spirit of the present invention and the scope of the appended claims.

Having thus described my invention, I claim:

1. In a press, a frame structure, a die slide mounted for reciprocation in said frame, means for reciprocating said die slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap cooperating with said eccentric means and including first and second arm members extending from said eccentric means, a link pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said second arm, a guide block pivotally attached to said frame and extending into said slot so that the pivotal axis thereof intersects said center line for constraining said second arm to move said connection between said link and said die slide in a closed path for causing said die slide to move in a work stroke and then in a return stroke at a substantially higher speed than the speed of the work stroke.

2. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a link pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said second arm, a guide block pivotally attached to said frame extending into said slot so that the pivotal axis thereof intersects said center line for constraining said arm to move said connection between said link and said die slide in a closed path for causing said die slide to move in a work stroke and then in a return stroke at a substantially higher speed than the speed of the work stroke, and means operatively connected to said eccentric strap and to said blank holder slide for reciprocating said blank holder slide into engagement with a blank prior to engagement of the blank by said die slide.

3. in a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a first link pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said arm, a guide block pivotally attached to said frame extending into said slot 50 that the pivotal axis thereof intersects said center line for constraining said arm to move said connection between said first link and said die slide in a closed path for causing said die slide to move in a work stroke and then in a return stroke at a substantially higher speed than the speed of the work stroke, a rocker member, means for connecting said rocker member to said blank holder slide, and a second link pivotally connected at one end to said rocker member and at the other end to said eccentric strap for moving said blank holder slide in timed relation to movement of said die slide.

4. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a first link pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said arm, a guide block pivotally attached to said frame extending into said slot so that the pivotal axis thereof intersects said center line for constraining said arm to move said connection between said link and said die slide in a closed path for causing said die slide to move in a drawing stroke and then in a return stroke at a substantially higher speed than the speed of the work stroke, a rocker member, means for connecting said rocker member to said blank holder slide, a second link, a first pivot connection connecting said second link at one end to said rocker member, a second pivotal connection connecting the other end of said second link to said eccentric strap for moving said blank holder slide in timed relation to movement of said die slide, and means for causing said second pivotal connection to move in a substantially circular path having said first pivotal connection as a center and said second link as a radius to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means which produces the drawing stroke.

5. -In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a first link member pivotally connected at one end to said first arm member and at the other to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said second arm, a guide block pivotally attached to said frame extending into said slot so that the pivotal axis thereof intersects said center line for constraining said arm to move said connection between said first link and said die slide in a closed path for causing said die slide to move in a drawing stroke and then in a return stroke at a substantially higher speed than the speed of the drawing stroke, a rocker member, means for connecting said rocker member to said blank holder slide, a second link member, pivot means pivotally connecting said second link member to said rocker member at a first pivot point, pivot means pivotally connecting said second link member to said eccentric strap member at a second pivot point for moving said blank holder slide in timed relation to said die slide, and means in one of said pivot means permitting relative movement between the tWo pivot points perpendicular to their pivot axes in addition to pivotal movement therebetween during the drawing stroke of the die slide.

6. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a link pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot in said second arm, said slot having a center line extending in the same direction as said arm, a guide block pivotally attached to said frame extending into said slot so that the pivotal axis thereof intersects said center line for constraining said arm to move said connection between said 1,-

link and said die slide in a closed path for causing said die slide to move in a drawing stroke and in a return stroke at a substantially higher speed than the speed of the drawing stroke, a rocker member, means for connecting said rocker member to said blank holder slide, a link member, a first pivotal connection connecting said link member to said rocker member, a second pivotal connection connecting said link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, means for causing said second pivotal connection to move in a substantially circular path having said first pivotal connection as a center and said second link as a radius to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means which produces the drawing stroke, and means in one of said pivotal connections permitting relative movement between the two pivotal connections perpendicular to their pivot axes in addition to pivotal movement therebetween.

7. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, a link pivotally connected at one end to said eccentric means and at the other end to said die slide for movin g said die slide in a drawing stroke and in a return stroke, a rocker member, means for connecting said rocker member to said blank holder, a second link, a first pivotal connection connecting said second link at one end to said rocker member, a second pivotal connection connecting said second link at the other end to said eccentric means for moving said blank holder slide in timed relation to movement of said die slide, and means for causing said second pivotal connection to move in a substantially circular path having said first pivotal connection as the center and said second link as a radius to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means which produces the drawing stroke.

8. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member cooperating with said eccentric means, means for connecting said strap member to said die slide, a rocker member, means for connecting said rocker member to said blank holder slide, a link member, a first pivot means for pivotally connecting said link member to said rocker member, a second pivot means for pivotally connecting said link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, and resilient means in one of said pivot means permitting relative movement between the two pivot means perpendicular to their pivot axes in addition to pivotal movement therebetween.

9. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member cooperating with said eccentric means, means for connecting said strap member to said die slide, a rocker member, a first link pivotally connected at one end to said rocker member and at the other end to said blank holder slide, a second link member, first pivot means pivotally connecting one end of said second link member to said rocker member, second pivot means pivotally connecting the other end of said second link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, means for causing said second pivot means to move in a substantially circular path having said first pivot means as a center and said second link as a radius to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means, and means permitting relative movement between the two pivot means perpendicular to their pivot axes in addition to pivotal movement therebetween.

10. A press as defined in claim 9 wherein said last recited means comprises a resilient material positioned between said link member and said first and second pivot means.

11. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said blank holder slide and said die slide, said means including an eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member cooperating with said eccentric means, means for connecting said strap member to said die slide, a rocker member having first and second arm members, a first link member, a first pivot means pivotally connecting one end of said first link to said first arm of said rocker member and a second pivot means pivotally connecting the other end of said first link to said blank holder slide, a second link member, a third pivot means pivotally connecting one end of said second link member to said second arm of said rocker member, fourth pivot means pivotally connecting the other end of said second link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, means for causing said fourth pivot means to move in a circular path having said third pivot means as a center to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means, and means permitting relative movement between the two pivot points perpendicular to their pivot axes in addition to pivotal movement therebetween.

12. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said holder slide and said die slide, said means including eccentric means rotatably axis thereof intersects said center line to move said connection between said link and said die slide in a closed path for causing said die slide to move in a drawing stroke and in a return stroke at a substantially higher speed than the speed of the drawing stroke, a rocker member having first and second arm members, a second link means for pivotally connecting the first arm of said rocker member to said blank holder slide, a third link member, a first pivotal connection connecting said third link member to said second arm of said rocker member, a second pivotal connection connecting said third link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, means for causing said second pivotal connection to move in a circular path having said first pivotal connection as a center to thereby provide a substantially constant pressure between the blank holder and a blank to be drawn during a portion of the rotation of said eccentric means which produces the drawing stroke, and means in one of said pivotal connections permitting relative movement between the two pivot points perpendicular to their pivot axes in addition to the pivotal movement therebetween during the drawing stroke of the die slide.

13. In a press, a frame structure, a die slide mounted for reciprocation in said frame structure, a blank holder slide mounted for reciprocation relative to said die slide, means for reciprocating said die slide and said blank holder slide, said means including eccentric means rotatably supported by said frame for rotation about a fixed axis, an eccentric strap member cooperating with said eccentric means, means for connecting said strap member to said die slide, a rocker member, means for connecting said rocker member to said blank holder slide, a

link member, a first pivot means for pivotally connecting said link member to said rocker member, a second pivot means for pivotally connecting said link member to said eccentric strap member for moving said blank holder slide in timed relation to said die slide, spacer means termed as a half cylinder wall positioned between said link member and each of said first and second pivot means, resilient means formed as a half cylinder wall positioned between said link member and each of said first and second pivot means, said spacer and resilient means together encircling each of said pivot means, said spacer means having grooves formed therein to allow said re- .silient means to expand therein upon compression of the supported by said'f-rame for rotation about a fixed axis, I

an eccentric strap member having first and second arm members extending from said eccentric means and cooperating with said eccentric means, a first lin-k pivotally connected at one end to said first arm member and at the other end to said die slide, means providing a slot through the center line in said second arm, a guide block pivotally attached to said frame and extending into said slot for constraining said second arm and where the pivotal resilient means to thereby permit relative movement between the members connected to the pivot means relative to one another in addition to pivotal movement therebetween.

References Cited in the file of this patent UNITED STATES PATENTS Engel Sept. 15, 1959

Claims

1. IN A PRESS, A FRAME STRUCTURE, A DIE SLIDE MOUNTED FOR RECIPROCATION IN SAID FRAME, MEANS FOR RECIPROCATING SAID DIE SLIDE, SAID MEANS INCLUDING ECCENTRIC MEANS ROTATABLY SUPPORTED BY SAID FRAME FOR ROTATION ABOUT A FIXED AXIS, AN ECCENTRIC STRAP COOPERATING WITH SAID ECCENTRIC MEANS AND INCLUDING FIRST AND SECOND ARM MEMBERS EXTENDING FROM SAID ECCENTRIC MEANS, A LINK PIVOTALLY CONNECTED AT ONE END TO SAID FIRST ARM MEMBER AND AT THE OTHER END TO SAID DIE SLIDE, MEANS PROVIDING A SLOT IN SAID SECOND ARM, SAID SLOT HAVING A CENTER LINE EXTENDING IN THE SAME DIRECTION