US2731140A - Drawing press - Google Patents

Description

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O. H. MAY

DRAWING PRESS Jan. 17, 1956 Filed May 2o, 1953 O. H. MAY

DRAWING PRESS `lan. 17, 1956 2 Sheets-Sheet 2 Filed May 20, 1955 .mrow/4 V Q WAVE United States Patent() DRAWING PRESS Otto Hermann May, Schwabiscli Gmund, Germany, as-

signor to May-Pressenbau G. n1. b. H., Schwalnsch Gmund, Germany, a corporation of Pennsylvania Application May 20, 1953, Serial No. 356,191

Claims priority, application Germany May 23, 1952 8 Claims. (Cl. 205-4) This invention relates to drawing presses, and more particularly to a crank-actuated drawing press having a main ram and a tool-carrying auxiliary ram which is guided in the main ram and is displaceable therein in a direction parallel to the axis of the main ram. The sequence of displacements of the rams relative to one another and relative to the frame is in a broad sense like that shown in the United States patent application of Otto Hermann May, Serial No. 78,765, filed February 28, 1949, for Drawing Press and eventuated as U. S. Patent 2,664,191, dated December 29, 1953. In particular the invention is an improvement upon that shown in said patent.

In said application is disclosed a frame carrying a drawing die. A crank-operated driving mechanism reciprocates a main ram through working strokes advancing toward the die and retractive strokes from it. An auxiliary ram is mounted for reciprocation between advanced and retracted positions on the main ram. This auxiliary ram carries the working tool for cooperation with the die. The auxiliary ram is adapted to be coupled in a forward position on the main ram when the latter is retracted. There it is held during movement of the main ram toward the die. Then upon retraction of the main ram, the auxiliary ram is decoupled and retracted with regard to the main ram. This occurs as the main ram is retracted. Before the main ram again reaches its drawing position, the auxiliary ram is again advanced and coupled to the main ram. The broad advantages of such a construction are set forth in said patent, among which are:

(l) Unlike prior machines, the pressure required at the beginning of the drawing operation is applied when the driving crank is in its most favorable position;

(2) Drawing progresses from the beginning at an increasing drawing speed to avoid an initial punching effect; and,

`(3) The stroke of the press is not, as is usual, more than double the length of the shell to be drawn.

The end result is'a press in which'theram is not required to move a substantial distance without doing any work, the press becomes smaller and less expensive in construction, and the press can be operated at a higher production rate with a longer useful life.

The above advantages also accrue to the present improvement, with the further advantage herein that the drive for the movement of the auxiliary ram relative to the main ram is provided by a pressure fluid-actuated mechanism controllably timed by the moving press members.

It is advantageous to design the driving mechanism in such a manner that the auxiliary ram can be driven by an actuating piston operated by the pressure medium and displaceable in a cylinder which is preferably arranged asa continuation of the main ram.

f Advantageously, the arrangement is such that the aux- -iliaryram is connected with the drive piston by a piston rod and that the forward movement of the auxiliary ram ice is limited by an abutment at the forward end of the ram while the return movement is limited by an abutment at the rear end of the main ram.

In order rigidly to connect the auxiliary ram with the main ram during the working stroke proper, the auxiliary ram is preferably interlocked with the main ram in the forward position of the auxiliary ram. Such interock can be accomplished, for example, by providing in the main ram locking elements, for example rotary keys, which are adapted to be engaged in corresponding recesses of the auxiliary ram under the action of a power accumulator.

To control the interlock, the main ram is advantageously provided with interlock control elements which are'controllable by additional interlock control elements provided on the press body, so that the interlocking elements can be disengaged by means of these interlock control elements.

The pressure medium provided for actuating the auxiliary ram may be controlled by special control devices. For example, a pressure medium control device may be provided on the main ram and adapted to be shifted in one direction by means of a cam provided on the crank drive, and in the other direction by means of a cam provided on the press frame.

Advantageously, the cam mounted on the press frame is so arranged that it is overrun during the forward movement of the main ram and acts upon the pressure medium control device only during its return movement, i. e., after the forward dead center position.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. l is a longitudinal section of the press, being taken on line I-I of Fig. 2, with the crank being shown shortly after its rear dead center position;

Fig. 2 is a fragmentary section of certain parts on line II-II of Fig. 1;

Fig. 3 is a fragmentary section similar to Fig. 1, with the crank shown about 30 degrees after its inner dead center position;

Fig. 4 is a fragmentary section through the interlocking device in the interlocking condition; and,

Fig. 5 is a fragmentary section through the interlocking device in the unlocked condition.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now more particularly to the drawings, a press body or frame 10 of a horizontal drawing press has two driving gears 11 supported therein in a manner not shown. The drive is derived from an electric motor and gearing which likewise is not shown in the drawings. The nature of such supports, motor and gearing is wellknown to those skilled in the art. Secured between the driving gears 11 is a crankshaft 12 on which a forked connecting rod 13 is journaled (see Fig. 2). The connecting rod 13 is pivoted on the main ram 15 by means of pin connection 14.

` The main ram 15, which is slidably supported on guide anges 101 of the press body 10, has a cavity 17 in its interior in which an auxiliary ram 16 is longitudinally displaceable. Forward axial movement of the auxiliary ram 16 is limited by rib 151 while rearward movement is limited by the back portion 152 of the main ram 15. A longitudinal slot 18 connects the cavity 17 with the outv side.

The auxiliary ram 16 carries on its forward face the drawing plunger 20, which is secured by means of a threaded bushing 19. The corresponding matrix or female die member 21 is mounted in the press frame opposite the plunger 20. At the rear end of the auxiliary ram 16, a piston rod 22 is engaged by its threaded forward end into a correspondingly threaded aperture. This piston rod 22 extends through the back portion 152 of the main ram 15 and carries at its rear end a piston 23 which is displaceable in a cylinder 26 secured to the back portion 152 of the main ram. Twovcompressed air conduits 24- and 25 connect the corresponding cylinder spaces 261 and 262 of cylinder 26 through a four-way valve 27 with a source of compressed air (not shown) and with the atmosphere, respectively. The control of the four-way valve 27 will be discussed in detail below.

Shifting of the four-way valve 27 is effected through a cam 28 secured to one of the drive gears 11 (Fig. 1) and acting upon a control lever 30 carrying a cam follower roll 29 and pivotally mounted on the press body 10 by means of a pivot pin 31.

A shifting lever 32, having a shifting head 321, is also pivotally mounted on the press frame by means of a pivot pin 33. A link 34 interconnects the levers 30 and 32. A tension spring 36, secured at 35 to the press frame 10, tends to pull the entire linkage 30, 32, 34 to the rear, such rearward movement being limited by a stop 37 provided on the press frame 10.

The four-way valve 27 has an inlet 271 and an outlet 272 for the compressed air; the supply line leading to inlet 271. has been omitted from the drawings for the sake of clarity.

The four-way valve 27 is provided at its top with an extension 273 on which a two-armed control lever 38 is pivoted, carrying a control roller 39 on its outer arm and a control roller 52 on its inner arm.

Pivotally mounted on the press body 10 is a control pawl 40 having a sloping forward edge, this pawl being urged rearwardly against an abutment 42 by a spring 41.

Arranged on the main ram is a locking mechanism for the auxiliary ram 16, which mechanism will be evident particularly from Figs. 2, 4 and 5. To this end the main ram 15 is formed, at two opposite points thereof, with outwardly widening slots 43 which establish communication between the outside and the cavity 17 of the main ram 15. Pivotally mounted on pivot pins 46 in these slots are dogs 44 carrying rolls 45, these rolls 45 projecting outward from they main ram 15. On the inner sides, the dogs 44 are provided with noses 441, the purpose of which will be discussed below. Blade springs 51 tend to rock the dogs 44 in such a direction that the noses 441 move to the rear.

The noses 441 extend inward into corresponding recesses 461 of rotary keys 53 mounted in the main ram 15 by means of pivot pins 47, said keys being adapted to be rocked so as to have their recesses move inward, by means of springs 49 secured at 48 on the main ram 15. Two unlocking cams 50 mounted on the press frame 10 are arranged to be engaged by the rolls 45 of dogs 44 during movement of the main ram 15.

The operation of the device according to the invention is as follows:

When the crankshaft 12 is approximately in its rear dead. center position, the main ram 15 will be in itsy rearmost position, which occurs shortly before the position of parts shown in Figs. l and 2. The auxiliary ram 16 will then occupy its rearmost position. Ask the drivev gears 11 continue to rotate and reach the position of Fig. 1, i. e., having advanced across rear dead center, the cam. 28'` will rock the cam follower roller 29 of control lever 30' forward about pivot 31, as shown in Fig. l, and. with the aid of link 34 will. also rock. control lever 32 forward about its pivot 33, whereby the control lever head. 321 will move the roll 39 of the two-armed control lever 28 to theleft. This rocking of control lever 28 will cause the compressed air supply to be directed to line 24 and the compressed air outlet to be connected to line 2S by means of the fourway valve 27, so that the piston 23 moves forward from its rearmost position (shown for example in Fig. 3) into the position shown in Fig. l, and through the piston rod 22 advances the auxiliary ram 16 to its most forward position in which it strikes against the abutment ribs 151 of the main ram 15. Upon continued movement of the driving gears 11, the cam 28 slides past the cam follower roller 29, whereupon the linkage 3l), 3-2, 34 is returned to its inoperative position engaging stop 37 under the action of spring 36.

Upon the above-mentioned forward movement of the auxiliary ram 16, the rotary keys 53 have their noses 531 engage corresponding recesses 161 of the auxiliary ram 16 and thus interlock the latter in its most forward position with the main ram 15, so that during the ensuing operating stroke the two rams 15 and 16 constitute a single rigid structure.

After a predetermined stroke the cam follower rollers 45 of dogs 44 engage the unlocking cam 50 and are thereby rocked rearward against the action of blade spring 51, as illustrated in Fig. 4. No action, however, is exerted upon the rotary keys 53. When the forward dead center position is reached, the cam follower roll 45 has been moved past the entire unlocking cam 50. When the idle retractive stroke commences, after passing through the forward dead center position, i. e., when the ram moves to the rear, the rollers 45 and dogs 44 are rocked forward and thereby cause the noses 441 to rotate the rotary keys 53 against the action of spring 49 such an amount` that the auxiliary ram 16 is unlocked or released as shown in Fig. 5.

During forward movement of the main ram 15, together with the auxiliary ram 16, the four-way valve 27 with its control lever 38 is moved past the control cam 40. During this travel, the position of the lever 38 does not change and always corresponds to that illustrated in Fig. 1. Such movement of the lever 38 past the control cam 40 is rendered possible by the fact that the cam 40 can be rocked forward against the action of spring 41. After the lever 38 has moved past, the cam 40 is returned to its` position 2f rest in engagement with stop 42 by the action of spring When the direction of movement of ram 15 is reversed after passing` through forward dead center, the control lever 38 is moved by control cam 40 into the opposite position illustrated in Fig. 3, which causes the four-way valve 27 to be shifted so that compressed air now Hows through conduit 25 into the space 262 of cylinder 26, while the air conlined` in space 261 is permitted to escape into the atmosphere through line 24. This position of the control lever 38 is illustrated in Fig. 3. Since, shortly after reaching the forward dead center, the auxiliary ramV 1.6 was unlocked as already described, the auxiliary ram 16 can now be drawn to its extreme rearward. position by the rearwardly moving piston 23. The position of this piston is evident from Fig. 3. After passage through the rear dead center, as already mentioned, the four-way valve 27 is again shifted throughcam 28 and linkage 30, 32, 34 so that the auxiliary ram 16 will bev pushed forward into its most advanced position according to Fig. 1.

It will be noted that, as in said Patent 2,664,191, ample space is provided between the front of. the main ram and the die 21 during the nal retractive movement of the main ram, which allows an operator at that time to insert the shell to be drawn without interference from the tool' 20. This advantage occurs by reason of the fact that the period of reciprocation of the auxiliary ram back and forth relative to the main ram covers a substantial period of the retractive movement of the main ram from the die. In other words, during nal retractive movement of the main ram ample space is left, by reasonof the retraction of' tool 20, to insert the shell to he drawn, without employing extra crank throw for the purpose.

' ln view of the above, it will be'seen that 'the'several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

l. In a press consisting of a frame, a main ram, mechanism adapted to reciprocate the main ram through working strokes and retractive strokes, an auxiliary ram mounted for reciprocation between advanced and retracted positions on the main ram, coupling means adapted to couple and decouple the auxiliary ram relative to the main ram, and means for reciprocating the auxiliary ram relative to the main ram when the rams are decoupled, said coupling means comprising at least one movable key in the main ram and intersecting a notched portion of the auxiliary ram, spring means biasing the key into the notch for automatic coupling when the auxiliary is in advanced position on the main ram, a stationary cam on the frame, and movable engaging means on the main ram adapted upon a retractive stroke of the main ram to engage said cam and said key and to move so as to disengage the latter from said notch.

2. A drawing press constructed according to claim 1, wherein said movable key and engaging means are rotary, the engaging means being movable independently of the key when the engaging means engages said cam upon a working stroke of the main ram. n

3. 1n a drawing press consisting of a frame, a drawing die supported by the frame, a main ram, a crank mechanism adapted to reciprocate the main ram through working strokes advancing toward the die and retractive strokes from it, an auxiliary ram mounted for reciprocation between advanced and retracted positions on the main ram and carrying a working tool for cooperation with said die, and coupling means adapted to couple and decouple the auxiliary ram relative to the main ram; a double-acting air cylinder and piston on the main ram adapted to reciprocate the auxiliary ram when decoupled; valve means carried on the main ram, operator means for the valve and movable therewith adapted in a first position to cause the valve to deliver air to said cylinder to force forward the auxiliary ram and in a second position to deliver said air so as to return the auxiliary ram, cam-operated means driven from the crank adapted to set said operator means in its iirst position when the main ram is retracted, and trip means on the frame adapted to move said operator means to its second position when the main ram executes a return movement.

4. A drawing press constructed according to claim 3, wherein said valve and operator means are carried on said main ram and reciprocate as a unit between said cam-operated means and said trip means.

S. A drawing press comprising a frame, a drawing die supported by the frame, a main ram, a crank mechanism adapted to reciprocate the main ram through working strokes advancing toward the die and retractive strokes from it, an auxiliary ram mounted for reciprocation between advanced and retracted positions on the main ram and carrying a working tool for cooperation with said die, coupling means adapted to couple and decouple the auxiliary ram relative to the main ram, a double-acting air cylinder and piston on the main ram adapted to reciprocate the auxiliary ram when the rams decouple, said coupling means comprising an opposite pair of rotary keys in the main ram and intersecting notched portions of the auxiliary ram, spring means biasing the keys into the notches for coupling, stationary cams on the frame, and rotary engaging means on the main ram adapted respectively upon a retractive stroke of the main ram to engage the stationary cams on' the frame to move so as to disengage the keys from the notches, valve means carried on the main ram, operator means for the valve means and movable therewith adapted in a first position to cause the valve means to deliver air to said cylinder to force forward the auxiliary ram and in a second position to deliver said air so as to return the auxiliary ram, cam-operated means driven from the crank adapted to set said operator means in its iirst position when the main ram is retracted, and trip means on the frame adapted to move said operator means to its second position when the main ram effects a return movement, said valve and operator means reciprocating as a unit with the main ram-between said cam-operated means and said trip means, whereby the cam-operated means acts upon said operator means only when the main ram is substantially retracted.v

6. A press comprising a frame, a main ram, a drive mechanism adapted to reciprocate the main ram through advancing working strokes and retractive strokes, an auxiliary ram mounted for reciprocation between advanced and retracted positions on the main ram, selfclosing latch means adapted automatically to lock the auxiliary ram to the main ram in response to forward positioning of the former on the latter, a double-acting fluid cylinder on the main ram and a piston therein connected with the auxiliary ram, a valve controlling flow of fluid to and from said cylinder on opposite sides of said piston, a multi-position operator for the valve adapted in a first position to set the valve to deliver uid to said cylinder on the side of the piston which will force the auxiliary ram forward to its locking position on the main ram, a first control means for said operator adapted upon rearward positioning of the main ram to place the operator in said first position, a second control means responsive to retractive movement of the main ram to actuate said latch means to release the auxiliary ram from the main ram, said operator being adapted in a second position to set the valve to deliver fluid to the other side of the piston to force the auxiliary ram rearward on the main ram, and a third control means adapted to set the operator into said second position as the main ram is retracted and after the latch means has released.

7. A press comprising a frame, a main ram, a drive mechanism adapted to reciprocate the main ram through advancing working strokes and retractive strokes, an auxiliary ram mounted for reciprocation between advanced and retracted positions on the main ram, self-closing latch means adapted automatically to lock the auxiliary ram to the main ram in response to forward positioning of the former on the latter, a double-acting lluid cylinder on the main ram and a piston therein connected with the auxiliary ram, a valve controlling ow of iluid to and from said cylinder on opposite sides of said piston, a multi-position operator for the valve adapted in a first position to set the valve to deliver uid to said cylinder on the side of the piston which will force the auxiliary ram forward to its locking position on the main ram, control means for said operator adapted upon rearward positioning of the main ram to place the operator in said first position, cooperating cam and follower means on the frame and main ram respectively responsive to retractive movement of the main ram to actuate said latch means to release the auxiliary ram from the main ram, said operator being adapted in a second position to set the valve to deliver fluid to the other side of the piston to force the auxiliary ram rearward on the main ram, and trip means adapted to set the operator into said second position as the main ram is retracted and after the latch means has released.

8. A drawing press comprising a frame, a main ram, a crank mechanism adapted to reciprocate the main ram through advancing working strokes and retractive strokes, an auxiliary ram mounted for'reciprocation between advanced and retracted positions on the main ram, a spring V7 latch adapted normally positively and automatically to couple the auxiliary ram to the main ram when the former is in forward position on the latter, cooperating cam and follower means on the frame and main ram respectively adapted in response to retractive movement of the main ram to move said latch from its normal position to release the auxiliary ram from the main ram, a doubleacrting. uid cylinder on the main ram and a piston therein, said piston being connected with the auxiliary ram, a valve carried on and movable with the main ram adapted to control ow of fluid to and from said cylinder on opposite sides of said piston, a two-position operator for the valve movable therewith adapted in a first position to set the valve to deliver uid to said cylinder to one side of the piston to force forward the auxiliary ram on the main ram and n a second position to deliver fluid to the other side of the piston to force it rearward so as to return the auxiliary ram when said latch is in release References Cited in the le of this patent UNITED STATES PATENTS 1,035,828 Albree Aug. 20', 1912 1,443,176 Gabriel Ian. 23, 1923 1,713,974 Massey May 21, 1929 1,870,527 Pardee Aug. 9, 1932 2,128,152 MacMillin Aug. 23, 1938 2,331,491 Menkin Oct. 12, 1943 2,417,781 Patrick Mar. 18 1947 2,664,191 May Dec. 29, 1953

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