US2764114A - Drawing press - Google Patents

Description

Sept. 25, 1956 K. GRIESINGER 2,764,114

DRAWING PRESS Filed4 May 6, 1952 7 Sheets-Sheet 1 K. GRlEsmGr-:R `2,764,114

Sept. 25, 1956 DRAWING PRESS 'r sheets-sheet 2 Filed May 6. 1952 Sept. 25, 1956 K. GRIESINGER 2,764,114

DRAWING PRESS Filed May 6. 1952 7 Sheets-Sheet 3 Sept 25, 1956 -K. GRIESINGER DRAWING PRESS 7 Sheets-Sheet 4 Filed May 6, 1952 Sept 25, 1956 K. GRn-:SINGER DRAWING PRESS 7 Sheets-Sheet 5 Filed May 6, 1952 /lmswmp ks L' 77 5y e f- Sept. 25, 1956 K. GRIESINGER DRAWING PRESS Filed May 6, 1952 7 Sheets-Sheet 6 il @ma MWF/VMI? K. GRIESINGER DRAWING PRESS 7 Sheets-Sheet '7 Filed May 6, 1952 |||l JY INPE/JIU@ 2,764,114 DRAWING PRESS Karl Griesinger, Goppingen, Wurttemberg, Jebenhausen, Germany, assignor to L. Schuler A. G., Goppingen, Wnrttemberg, Germany Application May 6, 1952, Serial No. 286,400 Claims priority, application Germany June 7, 1951 1 Claim. (Cl. 113-46) This invention relates to a drawing press for sheet metal having a draw punch and a die holder cooperating one with the other and, preferably, driven in opposing directions.

According `to the present invention the drives of the draw punch and of the die holder operate so that the draw punch is halted during the stroke of the die holder and the drawing begins near the stationary position of the draw punch which is preferably at a dead point of its drive means. The draw punch stroke is thus rendered fully utilizable. When the drawing begins near the halt position of the punch, the initial speed of drawing is very small whereas in prior machines the punch encounters the stationary sheet metal while moving at its greatest speed. The low initial speed protects the sheet metal in the drawing operation whereby operations that were possible previously only on high grade sheet metal can now be performed on sheets of inferior drawing properties.

A mechanism with oppositely driven die holder and draw punch can utilize nearly the entire draw punch stroke as depth of draw. Whereas in prior mechanisms in which die holder and draw punch are moved in the same direction the stroke of the draw punch must be at least twice the depth of draw, requiring large crank radius', high torque, and correspondingly large gear wheels, the mechanisms of the present invention allows the crank radius to be reduced to abou-t half, and also the torque. The gear wheels, with equal tooth load, are only half as large as in prior mechanisms.

A further feature of the invention consists in providing in the draw punch drive at least one driven planet wheel journalled in a rocking carrier and operated in such a manner that the drawing die is accelerated during its return stroke, is halted during the closing stroke of the die holder, and is driven during the work stroke without rocking movement of the planet wheel carrier. This makes it possible to extend the drawing stroke, beginning at the end position of the draw punch, over about 180 of the crank rotation, whereby, referring to a crank rotation, almost twice as much time is available for the drawing as in prior machines. With equal drawing speed, that means lthat the machine according to the present invention runs almost twice as fast and with equal drawing depth, making twice as many work strokes. As further operations on the drawn work piece can be performed much more rapidly than the rate at which the press can deliver them, this increase in `the operational speed of the press is of great importance in the industry from economy considerations.

According to another feature of the invention the rocking of the planet wheel carrier is derived from the drive of the die holder. For convenience the drive of the said carrier can be coupled to and uncoupled from the drive of the die holder in such a manner that the angular setting of the draw punch drive means relatively to the drive means of the die holder is capable of adjustment, for example, the position of a draw punch drive crank relatively to a die holder driving eccentric. According to the setting of the coupling means it is then possible to make the halt of the draw punch occur at desired positions whereby a desired depth of draw is determined.

States Patent 2,764,114 Patented Sept. 25, 1956 The invention will now be described by way of example and in several embodiments illustrated in the accompanying drawings, in which:

Figure l is a diagrammatic perspective lview showing a drive mechanism for a draw punch,

Fig. 2 is a similar View of a second embodiment,

Fig. 3 is a similar view of a third embodiment,

Fig. 4 is a diagrammatic perspective View of a drive mechanism `for a die holder, the parts being shown in the position which lthey occupy when the die holder is at the lower end of its stroke,

Fig. 5 is a view similar to Fig. 4 showing the die holder drive with the die holder at the upper end of its stroke,

Fig. 6 is a diagrammatic view of lthe coupled die holder and draw punch drive mechanisms.

Fig. 7 .is a diagram showing a time-travel curve and also sect-ion showing the movements of the die holder and the draw punch.

Fig. 8 is a longitudinal sectional View of a draw press equipped with the drive mechanism of the invention, and

Fig. 9 is a section transverse to `that of Pig. 8.

ln the example shown in Fig. l, 6 designates a drive pinion operating a gear 8 rota-tably mounted by means of a sleeve 44 on a shaft 28. The gear S engages a pinion 24 carried by a shaft 23. The shaft 23 is mounted in two rocking carriers 21 which can pivot about the shaft 2d. On the shaft 23 there is mounted a second pinion 26 engaging a gear 27, which latter constitutes a crank for actuating the push rod 29 of the draw punch 30. As long as the shaft 23 maintains its position relatively to the shaft 28, the wheel 27 is uniformly driven provided the gear 8 is driven uniformly from Ithe pinion 6. If the carriers 2l are rocked about the shaft 28 as lindicated by the 'arrows 48, in one or the other direction, then this rotary movement is added to or subtracted from the drive movement of the pinion 26', so that the gea-r 27 during the rocking of the shaft 23 in one direction is: accelerated, and during rocking in the opposite direction, is retarded. The arrangement may be such that the retardation halts the drive, that is, brings the draw punch to rest, While the acceleration produces its quick return stroke, and the drive, during the working stroke, proceeds with the carriers 21' held stationary.

Different results are obtained depending upon the in stant at which the swing of the shaft 23 and. the accom; panying planetary movement of the pinions 24 and 26' about the gears 8 and 27 is started or ended, also depending on the speed with which this travel is performed and whether it is effected with at uniform or non-uniform rate, also further it depends on whether the gears 8 and 27 and the pinions 24' and 26 have equal diameters and numbers of teeth as illustrated, or different diameters and numbers of teeth. The pinion 26', for example, may be of smaller diameter than the pinion 24', and the gear 27 of corresponding greater diameter than the gear 8.

In the example shown in Fig. 1, the gears 8 and 27 rotate in the same direction. For constructional reasons it may, however, be required that these gears rotate in opposite directions, when, for example, as hereinafter described, the punch movement is to be derived from the die holder movement.

According to the construction shown in Fig. 2, the gear 27 rotates in a direction opposite to the gear 8 while retaining the possibility for its retardation or acceleration by planetary movement of the drive pinion 26'. Two parallel shafts 22 and 23 are journaled in carriers 21 which pivot about the shaft 28. On the shaft 22 there is xed a pinion 24 driven from the gear 8. The same shaft carries a pinion 25 which engages a pinion 26 fast on the shaft 23. The shaft 23 thus turns in opposite direction as compared with the shaft 22. The shaft 23 also has xed thereon the pinion 26' which therefore drives "B Y 9 the gear 27 in the direction opposite to the rotation of the gear'S, contrary to the action of the mechanism shown in Fig. l.

in the example shown in Fig. 3 the general arrangement is similar to that of Fig. l to the extent that the planet wheel 26 is driven from the pinion 24 without reversal of direction. However, in this mechanism, instead of the continuous shaft 23, there is provided a jointed shaft 23". The part of the jointed shaft which carries the pinion 24' is supported in stationary bearings. The rotational movement imparted by the pinion 24 to the jointed shaft 23' is transmitted through the joint 53 and a slide muff S4 to a second portion `of the jointed shaft 23" which is journaled in rocking carriers 21 corresponding to those of Fig. 1. As a result of this arrangement the rotational speed of the planet wheel 26 about its own axis remains unchanged during the swing of the carriers 21, or depends only on the operation of the pinion 24', and not on the rocker movement, because the drive pinion 24 does not take part in the rocking movement of the carriers. A further result is that the diameter of the planet wheel 26 as compared with the diameter of the crank disk 27 can be determined as desired without dependence on the diameter of the pinion 24 and on its relationship to the diameter of the gear 8.

The drive of the die holder 19 in the embodiment of Fig. 4 is effected by an eccentric 9 carried by a shaft 28, which may be driven in the same manner as shown for the shaft 28 in Fig. 2. The eccentric 9 rotates in a strap 1t) from which extends an arm 10 pivoted by a pin 31 to an arm 32 of a bell crank lever 32, 33. This bell crank is provided with a bushing 35 permitting it to rock on the shaft 11. The arm 33 of the bell crank is jointed by a pin 34 to a link 13 to form a toggle joint, the other end of which link is joined by a pin 12 to an arm 14 fast onV a shaft journalled in the frame or casing of the machine. The shaft 15 also carries an arm 16 which is jointed by a pin 36 to a link 17 forming a toggle joint, the other end of which link being jointed by a pin 37 to an arm 3S fast on the shaft 11. The arm 38 may be provided with an extension 39 connected by a pin 40 to a tension link 2d) of which the other end may be connected to a shaft corresponding to the shaft 23 in Fig. 2 carrying the planet wheel 26 of the rocking carriers 21. Associated with the arm 39 there is another arm 39 xed on the shaft 11 to which at 40 there is jointed not only a second tension link but also the push rod 19', pivoted on a pin 40', for driving the die holder 19.

Fig. 4 shows the parts in the position which they occupy when the die holder 19 is in its lowermost position, While Fig. 5 shows the parts in the uppermost position of the die holder. This latter position is reached when the eccentric 9 in Fig. 4 moves counter-clockwise. The bell crank lever 32, 33 will then move from the position shown in Fig. 4 to that of Fig. 5. The toggle joint formed by the members 33, 34, 13, which is straight in Fig. 4, then is broken and assumes the position shown in Fig. 5 in which the arms 33 and 1,3 form an angle with each other which is less than 180. A similar action takes place at the completely or approximately straight toggle joint 36 of Fig. 4, in which the arm 16 and the link 17 reach the angularV position shown in Fig. 5. Finally, also the arm 39 and the push rod 19 move out of the dead point position into a position in which the arm 39 and the push rod lie at an angle to each other which is less than 180. When the eccentric 9 moves from the position of Fig. 4 through 180 counter-clockwise to the' position of Fig. 5, then the return movement of all the parts begins and these parts after a further half revolution of the eccentric again assume the position shown in Fig. 4. Thus there aro four dead point positions occurring in sequence, the dead point position of the eccentric 9, the dead point position of the toggle at 34, the dead point position of the toggle at 36, and the dead point position of the push rod mechanism at 40. The arrangement is such that the parts are not simultaneously in exact dead pointV position at all four places, there being slight differences. The result is that at the beginning of turning of the eccentric disk 9 from the position of Fig. 4, the die holder 19 at first remains substantially at rest and performs hardly noticeable oscillations. In this position of substantial rest the draw punch of the press is driven as shown more fully in Figs. 6 and 7.

Figs. 6 and 7 assume the arrangement in which the eccentric disk 9 of Figs. 4 and 5 is xedly connected to the drive gear 8 of the embodiment shown in Fig. 2, and in which Vthe links 20 and 20 of the embodiment of Figs. 4 and 5 are connected to the shaft 23 of the embodiment of Fig. 2. Contrary to the embodiment of Figs. 4 and 5 the joint 40" of the link 2Q does not coincide with the joint 4% or the push rod 19 to the lever arm 30. According to the separation of the two joints different modifications can be obtained.

in the diagrammatic showing of Fig. 6 the reference characters of the dilerent groups of parts according to the embodiments of Figs. 2, 4 and 5 are repeated. The eccentric rod 1d isl represented in Fig. 6 by a push rod 10 which is jointed to a circular disk rotating uniformly about the shaft 28. This circular disk has twelve equally spaced indicia markings 0 to ll. At the upper right hand part of Fig. 6 there can be read on a scale above the link 19, the amounts of its stroke travel which correspond to rotations from G to ll of the shaft 2S. The crank circle described by the joint of the push rod 29 for the draw punch 30 on the gear 27, is likewise divided into twelve angular divisions designated I to X11, which are, however of equal magnitude, since, as above explained, the planet wheel 26 which drives the gear 27 receives from the rocker 21 and the link 20', a rolling movement which accelerates or retards the wheel 27, such that the angularly spaced division 0 to l1 on the circle on the shaft 28 correspond to different angles I to Xll of the gear 27. The corresponding time-travel curves can be Seen in Fig. 7. While the die holder is closed through the range y, the drawing stroke x takes place, which extends over the draw depth z. The slighter rise of the time travel curve of the draw die during the Working stroke shows this smaller work speed as compared with the steep drop of the travel-time curve corresponding to the high speed return. In Fig. 7, at the right, the work piece 18 is shown in the die 18 drawn to the draw depth z, which die is fixed in the die holder 19, while the draw punch 3i) -is surrounded by a cylindrical member 45 which is xed to the stationary press table and constitutes the actual sheet metal holder.

Figs. 8 and 9 illustrate the invention as embodied in a carriage body press and combines the mechanisms of Figs. 2, 4 and 5. The press according to Figs. 8 and 9 combines the structure of Fig. 2 with the example according to Figs. 4 and 5 as diagrammatically set forth in Fig. 6. In this embodiment, however, the joint axes 40 and 40" of Fig. 6 coincide in a single axis 40. The drive means for the sheet metal die holder, as above described, is used four times, at the left and right as shown in Fig. 8, and at the front and back as shown in Fig. 9. The die holder thereore is driven at its four corners, while the draw punch 30 has a double drive, namely, at the left and right in Figure 8.

The general drive is derived from a tiy-wheel 1 which can be driven either directly or by belt, from an electric motor. Between the fly-Wheel 1 and the main drive pinion 41 there is interposed a unit 2 comprising a coupling and a brake. The pinion 41 drives the large wheel 3 of a first gear set, on the shaft 42 of which a pinion 43 is ixed said pinion meshing with the teeth 4 of the large Wheel of a second gear set. The shaft S of this second gear set carries a drive pinion 5' which engages a second pinion d of similar diameter and similar number of teeth which serves only to reverse the direction .of rotation. The pinion 5 drives the operating gear 7 of the left hand drive, Fig. 8, and the pinion 6 operates the correspondlng gear 8, of the right hand drive. The gears 7 and 8 therefore turn in opposite directions. The gears 7 and 8 are rotatably mounted on the shafts 28 with lnterposition of bushes 44. These gears have fixed thereto eccentric discs 9, which may be integral therewlth. On the eccentrics are mounted eccentric straps 10 from which extend eccentric rods 10. To each of these rods at 31 there is jointed an arm 32 of a bell crank 32, 33. The other parts of each die holder drive are similar to those shown in Figs. 4 and 5 and have Similar reference numerals.

The gears 7 and 8 also actuate two connecting rods 29 for the draw punch 30. The two co-axially arranged gears 8, see Fig. 9, and corresponding also co-axially arranged gears 7, operate pinions 24 which are each fast on an end of a shaft 22. Each of the shafts 22 is mounted 1n a pa1r of rockers 21 which can swing about the shaft 28, i. e., concentrically to the gears 7 and 8. Each pair of rockers also carries in addition to the shaft 22, a shaft 23 parallel thereto on which are mounted the pinions 26 which mesh with pinions 2S of equal number of teeth and equal diameter, mounted on the shaft 22. The gears 7 and 8 also mesh with the pinions 24, to rotate the shafts 22, which in turn drive through the pinions 25, and in opposite directions, the pinions 26. These pinions 26 are in engagement with the gears 27 which are rotatably mounted with interpositionvof bushes on the shafts 28, which gears 27 carry crank pins 46 on which are jointed connecting rods 29, the other ends of which actuate the draw punch 30, as indicated in Fig. 6 and as described in connection with Figs. 4 and 5, the links and 20 cooperate with the shaft 23 mounted in the rockers 21.

In Fig. 9 the pinions 26, for reasons of clearness, are shown withdrawn from the gears 27.

Modifications can be obtained by deriving the auxiliary drive of the draw punch in a different manner or from a different part of the die holder drive.

According to the example of Figs. 8 and 9 all the forces are sustained by the parts of the frame or body, without the use of tensioning anchorages. The frame comprises a bottom pan 50, an intermediate member 51, and an upper member 52. The frame comprises a table member 45 surrounding the draw punch and supporting the work, which table is substantially fixed but may be supported elastically, as, for example, by hydro-pneumatic means, or it may carry means for the elastic support of the sheet metal, for example, a sheet metal carrier actuated by compressed air. It is also possible to arrange the die holder in such a manner that it can be operated by air or liquid pressure, or be provided with an independent mechanical operation to enable it to perform an auxiliary work stroke. In the latter case the machine becomes triple acting.

In the example shown in Figs. 8 and 9 in which the cranks actuating the draw die rotate about a stationary main shaft, there is the advantage that the main shaft is not subject to torsion.

The opposing movements of the draw punch and the die holder make it possible to make the draw stroke and the die holder stroke of equal magnitude; however, the arrangement may also be such that the stroke of the draw punch is greater or smaller than the stroke of the die holder. The ejectors for the designated parts can be fixed in the upper part of the press. The entire drive for the draw punch and die holder can be enclosed in an oil bath.

In the following there is described the cooperation of the various parts as to their movements during a complete cycle of the drawing operation of the press wherein the drawing punch drive according to Fig. 2 and the drive mechanism of the blank holding punch according to the example of Figs. 4 and 5 operate in such a way that the drawing punch and the blank holding punch are driven counter to each other. The gear 8 is rigidly connected with the eccentric 9 and two pull links 20 and 20 connect the shaft 23 with the arms 39 and 39 on the shaft 11. As a starting position it is assumed. that the blank holder punch is in its uppermost position for a return movement and the drawing punch is in its lowest position for a return movement. Furthermore it is assumed that the pinion 6 rotates clockwise so that the gear 8 rotates counter-clockwise and that the gear 27 in turn rotates clockwise. The driven pinion 6 actuates the blank holder 19 through the eccentric 9 by means of the gear 8 and the driving parts, 10', 32, 33, 13, 14, 16, 17, 38, 39' and 19', from its top position to its bottom position. During approximately two-thirds of this movement, the rockers 21 will be swung downwardly by means lof the links 20 and 20 whereby the shaft 22 will be rotated in a counterclockwise direction, so that the gear 27 will remain motionless and also the draw punch 30 will be maintained in its bottom position. When the downward swinging movement of the rockers is almost completed, the pinions 24, 25, 26, 26 and the gear 27 will be driven by means :of the gear 8 and the draw punch 30 will be moved upwardly, whereby the actual drawing operation takes place. During this drawing operation the drive members 10', 32, 33, 14, 16, 17, 38, 39 and 19 of the blank holder 19 will pass over the dead-point position of Fig. 4; the blank holder 19 remaining so long in this position. After the draw punch 30 has completed its drawing step (approximately after a one-third movement of the stroke toward the bottom return position of the blank holder), the pinion 6 will actuate the drawing punch 30 again to the bottom position by means of the parts 8, 24, 25, 26', 27 and 29 and at the same time the blank holder 19 will be actuated to its t-op position (Fig. 5) by the parts 10', 32, 33, 13, 14, 16, 17, 38, 39 and 19'. `Thereby the rockers 21 will be swung upwardly by the links 20 and 20 as in Fig. 2; the pinion 24 rolling itself on the periphery of the gear 8 and will impart a normal rotary movement to the shaft 22 whereby the gear 27 will be accelerated as to its rotation by the pinions 25, 26 and 26' and thereby the drawing punch 30 will be rapidly returned to its bottom position.

I claim:

In a press for drawing sheet metal, a draw punch, a die holder, means to reciprocate the draw punch comprising a drive shaft, a first pinion on said drive shaft, a second shaft, a rst gear rotatable on the second shaft and meshing with said pinion, a rocker arm rotatable on said second shaft, a third shaft mounted in said rocker arm, a second pinion fixed on the third shaft and meshing with the first gear, an additional pinion on the third shaft, a second gear rotatable on the second shaft meshing with said additional pinion, a connecting link on the second gear operatively connected to the draw punch; means to reciprocate the die holder comprising, an eccentric on the second shaft, a first rock shaft, a bell crank lever rotatable on the first rock shaft and connected to the eccentric, a second rock shaft having a rst crank arm fixed thereon, a link connecting said first crank arm and the bell crank lever, a second crank arm fixed on said second rock shaft, a third crank arm xed on the first rock shaft, a link connecting the second crank arm and the third crank arm, a fourth crank arm on the rst rock shaft, a link connecting said fourth crank arm and the die holder to reciprocate same and a fifth crank arm on the second rock shaft and a link connecting said fifth crank arm and the third shaft to oscillate said third shaft about said first gear to cause a dwell in the operation of the draw punch.

References Cited in the file of this patent UNITED STATES PATENTS Glasner Oct. 21, 1941

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