US3266284A - Combined drawing die press and stretch forming apparatus - Google Patents

Description

6, 1966 s. M. DOLNEY 3,266,284

COMBINED DRAWING DIE PRESS AND STRETCH FORMING APPARATUS 4 Sheets-$heet 1 Filed March 5 1964 """Wlllli Aug. 16, 1966 s. M. DOLNEY 3,266,234

COMBINED DRAWING DIE PRESS AND STRETCH FORMING APPARATUS Filed March 5 1964 4 Sheets-Sheet 2 Q &

INVENTOR. M W/W BY ATTORNEY.

Aug. 16, 1966 s. M. DOLNEY COMBINED DRAWING DIE PRESS AND STRETCH FORMING APPARATUS 4 Sheets-Sheet 5 Filed March 5 1964 INVENTOR JZM, 7 1- 6 4 ATTORNEY.

Aug. 16, 1966 s. M. DOLNEY 3,256,284

COMBINED DRAWING DIE PRESS AND STRETCH FORMING APPARATUS Filed March 5 1964 4 Sheets-Sheet 4 GOCL 3 J INVENTOR.

arr/6 W W, BY

4* ATTORNEY.

United States Patent 3,266,284 COMBINED DRAWHNG DEE PRESS AND @TRETCH FORE HKNG APPARATUS Stanley M. Dolney, Parrna, @hio, assignor to The @yril Bath Company, Solon, Ohio, a corporation of @hio Filed Mar. 5, 1964, Ser. No. 349,621 1 Claim. (Cl. 72297) This invention relates to :a new and improved combined drawing die press and stretch forming apparatus and particulary to a new and improved hydraulic circuit therefor.

United States patent, to Cyril I. Bath, No. 3,116,780, issued January 7, 1964, discloses broadly a stretch forming fixture and combination thereof with a drawing die press, of the general character herein disclosed. However, with the advent of the higher alloys, extreme smoothness and precision in operation of the ram and stretch forming apparatus in relation to each other, and accurate control thereof, are essential.

The present invention has to do with changes in the hydraulic circuitry whereby such smoothness, precision, and accuracy are obtained.

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

FIGURE 1 is a front elevation of an apparatus embodying the principles of the present invention;

FIG. 2 is an enlarged top plan view of a unit of the stretch forming apparatus illustrated in FIG. 1;

FIG. 3 is a side elevation of the unit shown in FIG. 2;

FIG. 4 is an enlarged vertical sectional view through the stretch forming apparatus, taken on line 44 of FIG. 2; and

FIG. 5 is a hydraulic diagram of the structure illustrated in FIGS. 1 through 4.

Referring generally to the drawings, the invention is shown as incorporated in the conventional press 1, comprising a bed 2 with upright guide columns 3 arranged at the four corners thereof. A ram 4 is guided by the columns for vertical reciprocation. The bed supports a male drawing die 5 which is convexed upwardly. The ram 4 supports a complementary female drawing die 6 which is concaved downwardly. The dies 5 and 6 are complementary drawing dies which define, when closed, a concavo-convex pattern into which metal is drawn by the dies upon their closure. The usual hold-down devices about the periphery of the dies are not employed.

The ram 4 may be driven on its work and return strokes by any suitable power means. In the form illustrated, this means is shown as a reversible hydraulic piston and cylinder assemblage 7 including a cylinder 8, -a piston 9 reciprocable therein, and a piston rod 10 connected to the ram 4.

Mounted on the bed 2 is a stretch forming apparatus which preferably comprises two units 12 arranged one unit at each end of the male die 5. The units are the same in form and function, and are the same as those disclosed in the above-identified patent, and hence only one unit will be specifically described herein, and that only briefly.

Referring particularly to FIGS. 2 through 5, each unit comprises a base plate 13, on the ends of which are mounted guide supports 14 which support upright guides 15. Each guide has upright slideways 16 facing inwardly of the unit in a direction forwardly and rearwardly of the bed 2, and upward guide faces 17 at right angles to the slideways 16. Mounted for vertical reciprocation in the slideways is a stretch head elevator 20 which is guided thereby for movement upwardly and downwardly while the elevator itself remains parallel to its starting position.

For moving the elevator upwardly and downwardly, suitable piston assemblages 21 are provided, one at the front and one at the rear of the elevator 20. Each as semblage comprises a cylinder 22 mounted in fixed position on the elevator, a piston 23 reciprocal in the cylinder, and a piston rod 24. The cylinder 22 is arranged so that the piston rod extends downwardly, and at its lower end carries a tongue 25 by which it is pivotally connected, by a horizontal pivot 26, to a suitable yoke 27 which is fixedly secured at the base 14 of the associated guideway. The elevators 20 can be raised and lowered independently of the rise and fall of the ram.

In order to stretch the stock into a range above its elastic limits independently of the dies, suitable gripper heads 30 are provided, one for each unit 12. Each head comprises an elongated body 31 which extends in a direction from front to rear of the press bed 2 transversely of the direction in which the stock is to be tensioned. Each head has complementary gripping jaws 32 and 32a which cooperate with the cam surfaces 33 and 34 so that, when the jaws are moved toward the dies, they approach each other and grip the stock.

In order to close the jaws, the head 30 is provided with a plurality of reversible hydraulic piston and cylinder assemblages 36, having pistons 37 with rods 38 connected to the jaws.

All jaw operating piston and cylinder assemblages of each unit operate concurrently as a unit.

The head 30 can be moved toward and away from the dies independently of the operation of the elevator 20 and ram 4. For this purpose, each head 30 is mounted on a carriage or support 4t) which is mounted on the associated elevator 29 for movement toward and away from the path of the dies in a generally horizontal path.

To provide yieldable hydraulic pressure for stretch forming, reversible hydraulic stretch forming assemblies 42 are mounted on the elevator 20 and connected to the carriage. As described in the above patent, each stretch forming assemblage comprises a rigid block 44 having therein a row of cylinders 45. At its ends the body has trunnions 46 by which it is rockably supported on the elevator 20. Each cylinder carries a piston 47 with a rod 48 connected to a common link 49 which is connected, in turn, at one end to the elevator 20 and at the other to the carriage for driving the carriage 40 by the assemblage 42, all as more fully described in the above patent.

An important feature of the present invention resides in the manner in which the stretch heads 3% are operated in relation to each other and to the operation of the ram to tension the stock, and in the manipulation of the elevators relative to each other, to the ram, and to the tensioning means.

In the above Patent No. 3,116,780, the ram is operated by a power means which can be operated independently of the stretch forming assemblages. However, in the patent, each unit employs a single pump for operating not only its elevator 20 but also its stretch forming pistoncylinder assemblage 42.

A distinguishing feature of the present invention is that each unit 12 employs one pump and circuit for its stretch forming assemblage for moving its gripping head 30 toward and away from the path of the ram while tensioni-ng the stock, and a separate pump and circuit totally disassociated from the first pump and circuit for operating the piston and cylinder assemblage of its elevator 20. Either pump and its circuit may be used for operating the closure of the gripper jaws, and in the form illustrated, the jaw closure assemblages are connected to the pump which supplies the stretch forming assemblage.

Thus each pump is totally independent of the other and each unit is totally independent of the other unit. Furthermore, the ram is operated by a separate power means, such as a separate pump and motor which is independent of both units.

With this arrangement there is no drawing from the pump of one hydraulic piston and cylinder assemblage of a unit for supplying another assemblage of the same unit.

For example, change in the speed of operation of the elevator piston and cylinder assemblages cannot cause a change of pressure or volume of delivery in the stretch forming assemblage of the unit by temporarily drawing from the pump of th elevator assembly, and vice versa. Nor can stoppage of the elevator assemblage cause a sudden surge and increase in the pressure and volume of ,fluid to the stretch forming assemblage of the same unit by adding to the output of the pump of the latter and vice versa. This arrangement has several advantages. One is efiicient sizes of pumps. For example, if a single pump were employed for both elevator and stretch piston and cylinder assemblages, in each unit, it would have to have a considerable over-capacity and employ many control devices to maintain even approximately preselected variable or constant pressure and preselected variable or constant flow for all assemblages. In no event, even with mulltitudinous controls, could it provide the pressure control required for the higher alloys.

As to the latter, it must be borne in mind that a slight instantaneous relaxation or increase in pressure, followed immediately by a restoration of the original pressure or by overcompensation, results in a sudden jerk on the alloy material. This produces a permanent change in its elastic limit, ultimate strength, hardness, and ductility in short, in physical properties affecting formability. The resultant effect is tantamount to th use of materials of different original physical properties in the portion of the stock formed before the jerk and the portion yet to be formed. This greatly complicates the proper control and formation of each piece of stock, in many cases resulting in damage to the piece. It greatly increases the problem of duplicating consistently a large number of pieces. Considering th high price of such alloys, substantial losses in scrap soon increase the costs of the product to impractical limits.

It has been found that with this arrangement, extremely accurate control can be obtained for processing the stock, providing great advantages in case of the more exotic alloys, wherein the elastic limit and yield point are frequently extremely close to ultimate strength.

Referring to FIGURE 5, the circuitry employed is illustrated. The left hand unit 12 is provided with a pump 50, driven by a suitable motor 51. A pressure regulator 52, driven by a remotely controlled motor 53, and a flow regulator 54, driven by a remotely controlled motor 55 are provided. The regulators 52 and 54 are connected to the outlet of the pump and deliver hydraulic pressure fluid to the inlet side of a combined stop and reversing valve 56. The valve 56 controls the supply of hydraulic fluid to the assemblage 21. A second pump 58, operated by an electric motor 59, which, if desired, may be the same motor as motor 51, is used for supplying the pressure fluid to the stretch forming assemblage 42. The ptunp 58 delivers pressure fluid to a pressure regulator 60 operated by a remotely controlled motor 61, and through the regulator 60 to a flow regulator 62 operated by a remotely controlled motor 63. The discharge side of the flow regulator 62 is connected to the inlet side of a stop and reversing valve 64 which controls the supply of fluid to the stretch forming assemblage 42. The flow control 62 also applies hydraulic fluid to a stop and reversing valve 65 which controls the supply of fluid to the jaw operating assemblage 36. 1

All of the stop and reversing valves are solenoid driven and remotely controlled. The motors 53, 55, 61 and 63 also are remotely controlled.

The right hand unit is a duplicate of the left hand unit, and its ports are indicated by like numerals, but with a suffix a added.

In the illustrative example, independent pumps 50, 58, 50a and 58a have been shown as driven by independent motors 51, 59, 51a and 5901, respectively. However, the important feature is not the manner of driving the pumps but resides in providing independent pumps for each of the assemblages 21, 42, 21a and 4211 with each pump connected to its associated assemblages by a circuit separate and apart from the circuits between the other pumps and their associated assemblages, respectively. As a matter of economy in mechanical construction, the motors 51, 59, and 51a, 5911 may be a single electric motor having adequate power so that the demands made upon it by the various pumps would not cause any appreciable change in the rate of rotation. Likewise, if desired, the motor may be a double shaft motor with the pumps 50 and 58 on one shaft and the pumps 50a and 58a on the other shaft. Dual pumps mounted in a common housing and employing a common drive shaft, but isolated from each other hydraulically, are readily available on the market. One such could be the pumps 50 and 58 and another the pumps Stla and 53a hereof.

The importance of this circuitry can be more appreciated when it is realized that the cross section of dies varies greatly for different articles and different portions of the same article. Hence the combinations of the height of a stretch head of one unit, its rate of travel relative to the same, the amount of pressure that is supplied to its associated stretch unit, the relation between these pressures and rates for one unit 12 and those of the other unit 12 dependent upon the configuration of the die and the type of metal. For example, stretching the stock across a very sharp peak near one end of the die may require high tension combined with rapid downward movement of the elevator at such end of the die. If the other end of the die is somewhat fiat and gradually curved, much less tension and slower and less downward movement of the elevator may be required at the other end of the die. Differences in lateral slope of different portions of the die and irregular formations at localized areas also introduce complications. The possible combinations of pressures, speeds, and the like are infinite, and hence each requires precise control independently of the others.

With the arrangement herein described, however, a work piece can be formed by the proper correlation of the individually controlled operations hereinbefore described, involving the amount of tension, the direction of tension, the rate of rise or fall of the gripping heads by virtue of the elevators, the pressure applied for raising and lowering them, and all in preselected relations to the operation of the ram.

It is apparent, therefore, that many advantages may be obtained by the independent operation of each unit from the other and the independent operation of the elevation and stretch forming power of each unit.

Having thus described my invention, I claim:

A die drawing press and stretch unit combination, a ram movable along an upright path, ram power means for driving the ram, a frame at one side of the ram path, a carriage member, an elevator member, one of said members being mounted for movement on the frame, and the other member being mounted on said one member for movement relative thereto, the carriage member for movement in opposite directions to advanced and retracted positions along a fixed path transversely of said ram path, the elevator member for movement along a predetermined path to raised and lowered positions, a stock gripper carried by one of the members (for movement to raised and lowered positions by the elevator member and to advanced and retracted positions by the carriage member, power means to operate the gripper for gripping a margin of a piece of stock, yieldable carriage power means operatively connected to the carriage member for moving the carriage member to its said positions, selectively, elevator power means for moving the elevator member to its said positions, selectively, and said ram power means, elevator power means, and carriage power means each being operable independently of the others for effecting said movements of the ram, carriage member, and elevator member independently of each other, the power means for the elevator member including a reversible hydraulic piston and cylinder elevator assemblage, a first pump, -a circuit connecting [the first pump to said elevator assemblage, the power means for the carriage member including a reversible hydraulic piston and cylinder carriage assemblage, a second pump, a second circuit connecting said second pump and carri'age assemblage, sa-id circuits being separate from each other and operable independently of each other and of the power means of the ram, means to control each circutit independently of the other circuit, means to control the 1 am power rneans independently of the circuits.

References Cited by the Examiner UNITED STATES PATENTS 2,850,071 9/1958 Kraybill 72297 3,096,806 7/1963 Root 72-392 3,116,780 1/1964 Bath 72-2:97 3,224,241 12/1965 Dolney 72--305 CHARLES W. LANHAM, Primary Examiner.

L' A. LARSON, Assistant Examiner.

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