US3377835A - Hydraulic push rod for stretch draw press - Google Patents

Description

ed Dec 5 I [/6 6 ets-s II jill q I I i J iil l -lll /1 I l p l [u h ll 1' I 1| [I h I JIM I. ll j Y a April 16, 1968 s. M. DOLNEY HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS 6 Sheets-Sheet 2 Filed Dec. 30, 1965 I INVENTOR.

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April 16, 1968 s. M. DOLNEY HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS 6 Sheets-Sheet 15 Filed Dec. 30, 1965 INVENTOR.

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April 6, 1968 s. M. DOLNEY 3,377,335

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRES Filed Dec. 30, 1965 6 Sheets-Sheet 4 as F774. B 733M41 Ct 3- ATTORNEY.

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April 16, 1968 s. M. DOLNEY 3,377,835

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS Filed Dec. 50, 1965 e Sheets-Sheet 5 6 ATTORNEY.

April 16, 1968 s. M. DOLNEY 3,377,835

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS Filed Dec. 30, 1965 s Sheets-Sheet ATTORNEY.

United States Patent Filed Dec. 30, 1965, Ser. No. 517,616 8 Claims. (Cl. 72-305) This invention relates to stretch draw presses of the general type disclosed in Us. Patent of Paul F. Maize, No. 3,113,607, issued Dec. 10, 1963, and entitled, Prestretch Forming Fixture For Drawing Die Press.

In the above patent stretch units are arranged in a conventional drawing press at opposite sides of the die space. These units were provided with gripping heads which grip two opposite margins of a strip of stock and hold it under tension while it is drawn by companion drawing dies. The heads are supported on carriages which, in turn, are supported on vertically movable elevators. The heads can be moved relative to their respective elevators toward and away from the die space and the elevators can be moved vertically, during the concurrent stretching and drawing operation.

In the above prior structure the elevators are moved upwardly and downwardly by upright push rods mounted on the ram of the press. These rods are arranged so as to engage the tops of the elevators, after the ram has descended part way, and force them downwardly in fixed relation to the continued lowering of the ram. These push rods generally are manually extensible and contractible endwise. However, the rods strike the elevators with a severe impact and require very precise adjustment for proper operation.

In accordance with the present invention, push rod assemblages are provided which are continuously connected to both the ram and elevators and efiect lowering and raising of the elevators without the severe impact. The rod assemblages are such that precise adjustment of them axially, parallel to the ram and elevator paths, is unnecessary for proper operation and protection of the equipment. Also, the rod assemblages are so connected to the elevators so as to provide a cushioning effect when they become operative for lowering and returning the elevators.

Various specific objects and advantages of the present invention will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a front elevation of the stretch draw press embodying the principles of the present invention;

FIG. 2 is a right side elevation of the press illustrated in FIG. 1 and showing a hydraulic circuit employed in connection therewith.

FIG. 3 is an enlarged fragmentary front elevation of a portion of the press showing in greater detail one of the stretch draw units;

FIG. 4 is a top plan view of one of the stretch draw units and a portion of the press, illustrated in FIG. 3, part thereof being broken away for clearness in illustration;

FIG. 5 is a vertical sectional view of the stretch draw unit illustrated in FIG. 4 and is taken on the line 5-5 thereof.

FIG. 6 is a diagrammatic illustration of the stretch draw press of FIGS. 1-4, showing the driving hydraulic circuitry therefor.

Referring to the drawings the press comp-rises a frame 1 including upright corner posts 2, and a bolster block or bed 3. Mounted for vertical reciprocation on the upright corner posts 2 is a ram 4. The ram may be reciprocated vertically by any suitable means. In the form illustrated,

this means is shown as piston and cylinder assemblages 5 mounted on the top of the frame. Each assemblage 5 includes cylinders 6 having a piston 7 therein with its rod 7a connected to the top of the ram.

For die drawing the stock between companion drawing dies, a stationery fem-ale die D1 is mounted on the ram and a companion male die D2 is mounted on suitable supports 8 resting on the bolster block 3.

Mounted on the bolster 3, one at each end of the die D2, are stretch forming units 9. The units 9 are preferably identical and generally such as shown in US. Patent No. 3,116,780, of Cyril J. Bath, issued Jan. 7, 1964.

As illustrated in the drawing, each unit 9 comprises upright side frames 10 connected together by suitable transverse plates. An elevator 11 is mounted between each pair of side frame members for guided reciprocation in a vertical path, as more fully described in the above Bath patent.

Mounted on each elevator 11 is a tensioning unit which comprises generally a carriage 12 on which is secured a suitable gripping head 13. Each head includes a stationery gripping jaw 13a fixed securely on the carriage and a movable gripping jaw 13b pivoted to the carriage for rocking about a horizontal axis. The movable jaw is moved to and from open and closed position by a plurality of piston and cylinder assemblages 14. Each assemblage 14 includes a cylinder 15 having a transverse pivot 16, and a piston 17 having a rod 18. The pivot 16 of each cylinder provides a common pivot of two pivotally connected links 19 and 20, respectively. The piston rod 18 is pivotally connected to the stationery jaw or to the carriage by means of a pivot 21. Thus, the cylinder 14 floats with the links 19 and 20 as they rock about the axis of the pivot 16. The outer end of the link 19 is pivotally connected to the jaw 13b and the outer end of the link 20 is pivotally connected to the carriage 12.

On top of the elevator 11 is a horizontal trackway 22. The carriage is provided with a series of rollers 23 which ride on the trackway 22 so that the carriage can move horizontally relative to the elevator toward and away from the die space.

In order to apply yieldable tensioning force to the heads 13, a bank of like tensioning piston and cylinder assemblages 25 is provided. In the form illustrated, each assemblage of each bank comprises the cylinder 26 having a piston 27 with a piston rod 28 extending therefrom. The rods are pivotally connected by pivots 29 to suitable links 30. Each link 30 is connected at one of its ends to theelevator 11 by means of a pivot 31, and at its opposite end to the carriage 12 by means of a pivot 32. Each of the cylinders is mounted on its elevator 11 by means of trunnions 33 so that the cylinders can rock about a common horizontal axis and compensate for differences in elevation of pivot 29 and consequent upon rocking of the link 30.

By admission of pressure fluid to the head ends of the cylinders 26, yieldable tension is applied to the stock through the medium of the links 30, carriages 12, and heads 13 in all positions of the elevators.

The specific structure of the stretching units as thus far described is more fully shown and described in the above identified Patent No. 3,116,780 of Cyril J. Bath.

As mentioned, in the Maize patent the push rods are mounted on the ram of the press and are arranged to engage the elevators after the ram has moved partway downwardly and thereupon move the elevators downwardly. In the present instance, instead of the push rods described in Maize, a different type of push rod assemblies is pro vided for driving the elevators by the ram. These push rod assemblies comprise the improvement of the present invention.

In the improved form of structure brackets 36 are fixedly mounted on the opposite ends of the elevators, respectively. Mounted fixedly in upright position on each bracket for movement vertically therewith is an upright cylinder 37. Mounted in upright position on the ram are dependent push rods 38 which are in the form of piston rods arranged one for each cylinder 37. Each rod has at its lower end a piston 39 reciprocable in its associated cylinder 37. Each of the cylinders 37 is connected in a hydraulic circuit such that pressure fluid can be drawn into the head end of the cylinder freely, and discharged therefrom through a pressure relief or control valve. For convenience, both cylinders 37 of the same stretch unit 9 are connected in parallel to such a valve, though obviously each might have its own circuit.

As best illustrated in FIG. 2, the head end of the cylinders are connected by a conduit 40. A conduit 41 leads from the conduit 40 to an adjustable pressure relief valve 42' which can be adjusted for controlling the pressure developed in the head ends of the cylinders 37 due to downward movement of the rods 38 and pistons 39 by the ram. Each pressure control valve is set to release at a preselected maximum pressure.

The pressure control valve, in turn, discharges to a suitable sump 43. A conduit 44 connects a check valve 45 in parallel with the valve 42. The check valve 45 is arranged to open to permit free flow of the fluid from the sump into the head end of the associated cylinders 37 so that as the pistons 39 are lifted by rising of the ram, hydraulic fluid is drawn into the head ends of the cylinders, and to close to constrain the fluid to pass from the head ends of the cylinders 37 through the valve 42 upon downward movement of the pistons 39 by the ram.

A similar arrangement is used at the rod ends of the cylinders 37 if it is desired to dampen or cushion the application of lifting or return force to the elevators for lifting the elevators by the rods 38. For this latter purpose, a conduit 47 connects the rod ends of the cylinders 36 in parallel. A conduit 48 leads from the conduit 47 to the adjustable pressure relief valve 49, similar to the valve 42, the pressure valve having its discharge connected to the sump 43. A line 50 connects a check valve 51 in by-passing relation to the valve 49. The check valve 51 is arranged to open so as to permit free flow of fiuid from the sump to the rod end of the cylinders during lowering of the pistons 39 by downward movement of the ram to force the pressure fluid in the rod ends of the cylinders to pass to the valve 49 upon lifting of the pistons 39 by the ram. 7

When the ram begins lowering it does not instantly initiate the downward travel of the elevator as it would were solid or rigid push rods provided. Generally it is desired to lower the ram part way and gradually build up pressure in the head ends of the cylinders 37 to render the rods effective for driving the elevator. The inherent yieldability in the fittings and conduits of the hydraulic circuit are adequate to reduce the shock to a negligible amount.

The valve 42 may be set so that downward pressure built up in the head ends of the cylinders 37 by the pistons upon lowering of the ram soon becomes suflicient to force the elevator downwardly against the resistance of metal being stretched and drawn, whereupon the ram and the elevator lower together because of the hydraulic locking of the pistons 39 and cylinders 37 in the downward direction. Thus the shock absorbing effect is provided before the downward starting of the elevator.

The force at which a particular elevator is to be moved downwardly can readily be determined for a given operation and the relief valve 42 of that elevator is set so that when such force is exceeded, the valve opens sufliciently to prevent further increase. It is to be noted that each elevator has its own circuit and valves 42 and 49, so that each can be separately controlled. Downward movement of an elevator can be arrested by closure of the dies or bottoming of the elevator in its supporting frame, or by placing stop blocks 52 disposed between the frame of an elevator and the associated elevator. These blocks may be arranged in sets of difierent selected heights, the set used depending upon the lowered position in which downward movement of a particular elevator is to be arrested. The valve necessarily opens, relieves the pressure, and thereby protects the equipment when downward movement of the elevator is arrested.

For the purposes of illustration, the units and ram are shown as controlled manually by circuitry, including remote control valves as illustrated in FIG. 6.

The circuitry for operating each stretch forming unit is separate from, but identical with, that of the other, and only one will be referred to in detail herein.

Each unit is supplied with hydraulic pressure fluid from a pump 56 driven by a motor 57. The pump 56 is connected to a suitable control valve 59 which supplies pressure fluid to the stretch forming piston and cylinder assemblages 25. The valve 59 is arranged so that the flow of hydraulic fluid to the ends of the assemblage can be reversed and the ends opposite the pressure ends connected to a sump. When the valve 59 is in an intermediate position the cylinders 25 are hydraulically locked so that the associated unit can function merely as an anchorage, all stretching being performed by the opposite unit.

The pump 56 also supplies pressure fluid through the solenoid operated valve 61 to the cylinders 15 of the gripper jaw operating assemblages.

The fluid delivery to the piston and cylinder assemblages may be regulated by conventional remotely controlled hydraulic pressure and flow operators. For example, a settable pressure regulator 62, which may be remotely controlled by a driving motor 63, is provided between the valve 59 and the pressure side of the pump 56. A similar regulator 64, operated by remotely controlled motor 65, is interposed between the pressure side of the pump 56 and the valve 61.

The controls for the valves and regulators of both units are operable from a common panel.

As herein shown, the pressure fluid for operation of the ram is supplied by a motor 67, having its pressure side connected to the assemblages 5 by a conduit 68 through a remotely settable pressure control regulator 69 and solenoid operated valve 70. The valve 70 can hydraulically lock the assemblages 5 or supply pressure to the head ends of both concurrently for forcing the ram downwardly while venting the rod ends of the assemblages 5. The valve 70 may be set to reverse the flow of hydraulic fluid for lifting the ram.

Necessarily the maximum pressure applied to the elevator by the ram upon movement of the ram on its forming stroke is much greater than that imposed on the elevator by the ram as the ram moves on its return stroke. Accordingly, the valve 42 may be set at relatively high pressure determined by the pull-down force required for forming a particular piece of metal. The valve 49, on the other hand, may be set at relatively low pressure so as to assure lifting of the elevator and return of the piston 39. This pressure is dependent on the weight of the elevator and the parts supported thereon, and should be just enough to cause return of the elevator while not unduly resisting the return of the ram after the elevator has reached its return position and the piston 39 is being returned relative to its cylinder.

For purposes of illustration herein, the cylinders 37 have been shown as connected to the elevator bracket 36 and the push rods 38 connected to the ram. However, if desired, these cylinders and push rods may be reversed, the cylinders being connected to the ram and the push rods to the bracket of the elevator.

Having thus described my invention, I claim:

1. A stretch draw press comprising a bed having a die supporting space;

an upright frame;

a ram carried by the frame and movable in an upright path toward and away from the bed in vertical alignment with the die space;

power means for driving the ram;

gripper means carried by the bed at one side of the die space;

a stretch forming unit on the bed at the other side of the die space including an elevator movable in a generally upright path, a carriage on the elevator and movable relative thereto in a generally horizontal path, stretch forming means for moving the carriage and for yieldably resisting movement thereof, respectively, relative to the elevator along said horizontal path, and a gripping head on and movable with the carriage;

said heads being adapted to grip opposite margins, re-

spectively, of a sheet of metal for applying tension thereto;

power transmission means drivingly interconnecting the ram and elevator for driving the elevator downwardly by the ram;

characterized in that means are provided in the transmission means for limiting to a preselected maximum the force transmittable by the transmission means from the ram to the elevator on the forming stroke of the ram.

2. A stretch draw press according to claim 1 wherein the transmission means includes a normally closed hydraulic circuit and the force is transmitted through the hydraulic fluid therein, and a pressure relief valve is connected in the circuit for releasing fluid therefrom when the pressure of the fluid in the circuit exceeds a predetermined maximum.

3. A stretch draw press according to claim 1 wherein additional means are provided in the transmission means for limiting to a lower predetermined maximum the force transmitted by the transmission means from the ram to the elevator on the return stroke of the ram.

4. A stretch draw press according to claim 1 wherein the transmission means includes yieldable shock absorbing means which reduce shocks imposed on the elevator by the ram during movement of the ram on its forming stroke.

5. A stretch draw press according to claim 1 wherein said power transmission means are extensible and retractable push rods, each rod comprising a piston and cylinder assemblage including a piston member and a cylinder member, means connects one of the members to the ram for movement in a fixed relation thereto as the ram moves downwardly; means connecting the other member to the elevator for movement in fixed relation thereto as the elevator moves downwardly;

pressure relief valve means are provided;

a hydraulic circuit connects one end of the cylinder member to the valve means so that the movement of the piston member relative to the cylinder member in one direction upon downward movement of the ram is resisted by the fluid pressure which is dependent upon the pressure at which the valve releases hydraulic pressure fluid from said one end of the cylinder; and

means are provided for admitting hydraulic fluid pressure to said one end of the cylinder member upon relative movement of the members in the opposite direction.

6. A stretch draw press according to claim 5 wherein an additional pressure relief valve means is provided, an additional hydraulic circuit connects the other end of the cylinder member to the additional valve means so that movement of the piston member relative to the cylinder member in the said opposite direction is resisted by a preselected pressure depending upon the pressure at which the additional valve releases hydraulic pressure fluid from said other end, and additional means are provided for admitting hydraulic fluid to said other end of the cylinder member upon relative movement of the members in said one direction.

7. A stretch draw press according to claim 5 wherein the piston member is connected fixedly in position on the ram, and the cylinder member is connected fixedly in position on the elevator.

8. A stretch draw press according to claim 5 wherein said push rods are connected to opposite sides of the elevator, respectively.

References Cited UNITED STATES PATENTS 1,315,937 9/1919 Artz 72305 X 3,073,373 1/1963 Wheeler 72297 3,113,607 12/1963 Maize 72-296 3,116,780 1/1964 Bath 72297 CHARLES W. LANHAM, Primary Examiner.

K. C. DECKER, Assistant Examiner.

Claims (1)

1. A STRETCH DRAW PRESS COMPRISING A BED HAVING A DIE SUPPORTING SPACE; AN UPRIGHT FRAME; A RAM CARRIED BY THE FRAME AND MOVABLE IN AN UPRIGHT PATH TOWARD AND AWAY FROM THE BED IN VERTICAL ALIGNMENT WITH THE DIE SPACE; POWER MEANS FOR DRIVING THE RAM; GRIPPER MEANS CARRIED BY THE BED AT ONE SIDE OF THE DIE SPACE; A STRETCH FORMING UNIT ON THE BED AT THE OTHER SIDE OF THE DIE SPACE INCLUDING AN ELEVATOR MOVABLE IN A GENERALLY UPRIGHT PATH, A CARRIAGE ON THE ELEVATOR AND MOVABLE RELATIVE THERETO IN A GENERALLY HORIZONTAL PATH, STRETCH FORMING MEANS FOR MOVING THE CARRIAGE AND FOR YIELDABLY RESISTING MOVEMENT THERE-

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