US2750909A

US2750909A - Press

Info

Publication number: US2750909A
Application number: US133450A
Authority: US
Inventors: Arthur A Byerlein
Original assignee: Baldwin Lima Hamilton Corp
Current assignee: Baldwin Lima Hamilton Corp
Priority date: 1949-12-16
Filing date: 1949-12-16
Publication date: 1956-06-19
Anticipated expiration: 1973-06-19

Description

June 19, 1956 A. A 'BYERLEIN PRESS 6 Sheets-Sheet 1 Filed Dec. 16, 1949 F l I I i l Il e l lll llll ll 70 7165 Qi/4% sa gmc/wm ATTORNEYS June 19, 1956 A. A. BYERLEIN PRESS 6 Sheets-Sheet 2 Filed Dec. 16, 1949 ATTOR N EYS June 19, 1956 A, A. BYERLEIN 2,750,909

PRESS Filed Dec. 16, 1949 6 Sheets-Sheet 3 ATTORNEYS June 19, 1956 A. A. BYERLEIN 2,750,909

PRESS Filed Dec. 16, 1949 6 Sheets-Sheet 5 1oz 101 104 99 1oz zzo 203 204 1oz El -9 10o 205 zoo ,35o

32 26 i2 30 ,f a1 21o 2o? 9 'e Q j 27 O z3 9a 706 JMG/MWL 53 e 4Z QMWA 24o 245 0)? g M ATTOR N EVS June 19, l956 A. A. BYERLEIN 2,750,909

' PRESS Filed Dec. 16, '1949 6 Sheets-Sheet 6 ATTORNEYS United States Patent O PRESS Arthur A. Byerlein, Detroit, Mich., assignor to Baldwin- Lima-Hamilton Corporation, a corporation of Pennsyl- Vania Application December 16, 1949,*Serial No. 133,450

4 Claims. (Cl. 113-38) This invention relates to presses, and more particularly to drawing, forming and stamping presses such as are u sed for forming metal parts in the manufacture of automobile bodies and parts thereof, and the like.

The invention has particular relation to multiple action presses having two or more slides which execute working strokes on the sheet cr blank in timed relation with each other, with one or more of the slides operating with a dwell in its movements during which time it acts to hold the blank in proper position for the working stroke of another slide or slides.

In presses of this type wherein one of the slides executes a forming stroke on the blank in the opposite direction to the working stroke of the blank holding slide during the dwell of the blank holding slide, it is sometimes found that the forming pressure against the blank holding slide tends to move the latter away from the blank. AS a result, the desired holding pressure on the sheet or blank is not maintained, and spoilage of the sheet may result. It will of course be understood that even in a press of the great size and weight used for parts of automobile bodies and the like, this undesirable movement of the blank holding slide is relatively slight, but is requires a movement of only a few thousandths of an inch to spoil the work. For example, in presses of this type, the blank holding slide is initially carefully adjusted with respect to the cooperating blank supporting parts of the press in accordance with the thickness of the sheet to be run, and if a sheet in the batch should be as little as 0.005 inch less than the thickness for which the press is adjusted, it may be drawn in too easily and wrinkled as a result of insutlicient holding pressure. 'I'his is true apart from the question of possible movement of the blank holding slide resulting from the opposed forming pressure of another slide, and it will be seen that the situation is further complicated if no provision is made for compensating for such movements of the blank holding slide.

It is accordingly one of the principal objects of the present invention to provide a multiple action press having a plurality of slides arranged to execute working strokes in opposite directions on a sheet or blank wherein the slides and other cooperating parts of the press are arranged to maintain the proper pressure of the blank holding members on the sheet notwithstanding movements of these members and of the sheet,- occasioned by the forming operations on the sheet.

Another object is to provide a multiple action press having upper and lower slides operating in opposite directions wherein the lower blank holding member is yieldably supported in the frame of the press in such manner that it automatically accommodates itself to movements of the upper blank holding member during the work cycle of the press to maintain the proper holding pressure on the blank throughout the forming operations thereon.

Still another object is to provide a multiple action press having a pair of inner and outer slides arranged to ice execute working strokes in the same direction wherein the inner slide and the drive mechanism therefor are wholly supported by the outer slide in such manner that the inner slide is carried by the outer slide during the working stroke of the outer slide and is then caused to execute its own working stroke while the outer slide dwells and holds the blank.

It is also an object of the invention to provide a triple action press in which two of the slides execute working strokes in opposite directions and are arranged to operate with coincident dwells to hold the blank during the working stroke of the third slide and wherein the blank holding members are yieldably arranged for limited movement in such manner as to maintain proper work holding pressure on the blank during all the forming operations thereon.

A further object is to provide a triple action press in which'one of the three slides and the drive mechanism therefor are Wholly supported and carried by one of the other slides, and other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawings- Fig. l is a front elevational view of a triple action press in accordance with the invention, with portions broken away in vertical section to illustrate details of internal construction;

Fig. 2 is an elevational view of the left-hand end of the press, showing the toggle mechanism for operating the outer slide in the position corresponding to the lower dead center position of the slide;

Fig. 2a is a fragmentary view of the motor and drive connection for completing Fig. 2;

Fig. 3 is a vertical section on the line 3 3 of Fig. l, showing the toggle mechanism for operating the lower slide in the position corresponding to the upper dead center position of the slide;

Fig. 4 is a fragmentary view looking in the same direction as Fig. 2 to show the toggle mechanism and associated structure for operating the outer slide of the press, and showing the parts in the position corresponding to the upper dead center position of the slide;

Fig. 5 is a fragmentary view showing the toggle mechanism and associated structure for operating the lower slide in the position corresponding to the lower dead center position of the slide;

Fig. 6 is a somewhat diagrammatic view in vertical section through the bed and the lower slide, the view being taken approximately on the line 6-6 of Fig. 7;

Fig. 7 is a sub-assembly View of the bed and lower slide which is partly in front elevation and partly broken away and in section on the line 7-7 of Fig. 3;

Fig. 8 is an enlarged detail view taken in section on the line 8-8 of Fig. 7 to show the supporting and adjusting mechanism for one corner of the blank holder ring;

Fig. 9 is a view of the upper slides which is partly in plan and partly in horizontal section as indicated by the line 9-9 of Fig. 10;

Fig. 10 is a view partly in front elevation and partly vertical section generally on the line 10-10 of Fig. 9;

Fig. 11 is a somewhat diagrammatic view in transverse vertical section illustrating a Work operation of the press;

Fig. 12 is a graph showing diagrammatically the relative sequential travel of the slides during a complete operating cycle of the press; and

Fig. 13 is a diagrammatic showing of electrical controls for the cycle of the press.

The drawings, which illustrate a preferred embodiment of the invention, show a triple action press wherein the frame includes a bed having end portions 20 connected by front and

rear portions

21 and 22, respectively,

Patented June 19, 1956 the bed ends also including projections 23vwhich are adapted to rest on suitable supporting columns 24 below the oor 25. Spaced uprights 26 are mounted on the bed ends 20 and are connected by an upper or arch portion 27, the upper slides being supported' in the uprights 26 for reciprocating movement with respect to the bed.

The outer die slide 30 of the press is provided with four tie rods 31, which are connected in pairs to the ends of the slide and extend downwardly into the bed for connection to the drive mechanism of the press, and slide 30 is provided with suitable guides 32 (Fig. 9) extending along the frame uprights 26. The inner die slide 33 is supported within outer slide 30 for reciprocating movement with respect to slide 30 along the guides 34 (-Fig. 9), and its drive mechanism is also supported on the outer slide for operation in timed relation with the drive for the outer slide. The lower slide 35 is located within the bed and is arranged to execute its working stroke in the opposite direction to the upper slides.

In the working operation of this press, the outer slide 30 performs .its working stroke first, descending to a predetermined position above the bed and then dwelling in that position, during which dwell period it cooperates with the blank holder ring 4t) supported by the bed to holdI the sheet or blank for the working operations of the other slides. The lower slide 35 executes its upward working stroke during the dwell period of the outer slide, and after its stroke is completed it also dwells. During this dwell period of both of the

slides

30 and 35, the inner slide 33 is caused to performl its working stroke, and thereafter the cycle is completed by the return of all three slides to their original positions. These operations are illustrated by and will be readily understood from the curves shown in Fig. l2, which illustrate the relative sequential movements of the three slides during a complete cycle of this press, the curve A representing the outer slide 30, the curve B the lower slide 35, and the curve C the inner slide 33.

The main drive motor 44 of the press is shown in Fig. 2a as mounted on a base 45 on the pit oor below the press, and it has a drive pulley 46. Drive belts 47 connect pulley 46 with the sheave portion of a flywheel 59 which is mounted on a shaft 51 carried by brackets 52 projecting from the front of the bed. The flywheel is shown as provided with a clutch 53 for selectively connecting and disconnecting the flywheel to shaft 51, and a brake for shaft 51 is indicated at 54. A drive pinion 55 on shaft 51 engages a gear 56 on a shaft 60 supported at opposite ends of the bed by brackets 61. At each end of shaft are pinions 62 engaging the large gears at each end of the main crank shaft 66, which is ournaled in the bearing brackets 67 (Figs. 1 and '7) bolted to the end portions 20 of the bed and in bearings supported by the pair of beams 68 which extend across the middle of the bed and are bolted to the

bed portions

21 and 22 as shown in Fig. 3.

The drive connections between the main crank shaft 66 and the outer slide 30 are located at the opposite ends of the press. Each of the large gears 65 includes an eccentric hub portion 70 on which is rotatably mounted an eccentric strap 71 having its upper end connected by a pin 72 to a member 75 mounted for vertical sliding movement in the end portion 20 of the bed. Two links 76 are pivotally connected at one end to the opposite sides of the sliding member and at their opposite ends to a bell crank lever 77 mounted for rocking movement on a pin 78 supported in boss portions of the bed ends 20 and the end plates 79 of the bed as shown at the left .in Fig. l, there being a pair of these levers and pins at each end of the bed, A link 80 connects each of the levers 77 with another bell crank lever 81 mounted for rocking movement on a pin 82 similarly supported by the

bed portions

20 and 79, there being a pair of levers 81 and pins 82 at each end of the bed. Each lever 81 i includes an extended bifurcated arm portion 83 which is pivotally connected with the upper end of an elongated link 85 to form a toggle, and the lower end of each link S5 is pivoted to an opstanding yoke portion 86 of a beam SS.

The lower ends of the tie rods 31 for the outer slide 3G are secured to the beams 8S to operate the slide in response to the reciprocating movement imparted to the beams 88 through these toggle linkages. The tie rods 31 are shown as pre-stressed and encased in sleeves 90 9 and l0) to prevent them from such stretching in use as would be likely to cause non-uniform results in the operation of the press, and the lower end of each tie rod is connected to one of the beams 88 as indicated at 91 in Fig. l.

The upper ends of these tie rods 31 are adjustably conrie-:ted to the slide 3l) to provide for varying the starting position of the slide in accordance with desired operating conditions. Referring to Figs. 9 and l0, the upper end of each sleeve 94) includes a threaded portion 92 which engages in a cylindrical nut 93 rotatably mounted in a housing 94 secured to the slide. The outer surface of each nut 93 is provided with worm teeth meshing with a worm 9S on a shaft 96 driven by an adjusting motor 99 through suitable gearing indicated generally at 160, 101 and 1&2, the motor 99 being supported by

beams

103 and 104 which extend across the upper part of slide 39 and are bolted thereto. Thus when motor 99 is operated, the nuts 93 are rotated and act through their threaded connections with sleeves to raise or lower the slide 3i) on the tie rods, a similar adjustable connection being illustrated in Byerlein Patent No. 2,378,- 062 issued June 12, 1945 and assigned to the same assignee as this application.

Fig. 4 shows the position of the toggle linkages and associated parts for operating the outer slide 30 in their relative positions corresponding to the upper dead center position of the slide 30. As each of the gears 65 is r0- tated, the associated eccentric strap 71 moves downwardly and pulls the operating member 75 similarly downwardly. This movement is transmitted through the links 76 to the levers 77 to cause the latter to rock and thus to act through the links S0 to cause similar rocking movement of levers 81. As a result, the linkages composed of the lever arms 83 and the elongated links 8S are straightened out as shown in dotted lines in Fig. 2 to produce a downward thrust on beams 8S, with accompanying tension on tie rods 31 to pull the slide 36 downwardly toward the bed, and the arrangement is such that slide 30 is reciprocated with a prolonged dwell in its lower dead center position as indicated by the curve A in Fig. l2. The slide 30 is also shown as provided with a counterbalance comprising a plurality of air cylinders 105 mounted at op posite ends of the press in the uprights 26 and containing pistons operated by piston rods 106 extending downwardly from the outer ends of slide 30.

During its dwell period, the slide 30 acts to hold the blank for operation thereon by the other slides, and it carries a bolster 110 (Fig. ll) having the usual holes 111 therethrough for receiving pressure pins. The boister is supported by a pair of bolster rods 112 which are suspended from a beam 113 extending transversely across the middle of slide 30 at its upper end and bolted thereto at 114. ln addition, the bolster may be secured at its periphery to the peripheral flange at the lower end of slide 30 as indicated at 115 in Fig. l1, and the bolster is also shown in Fig. ll as supporting an upper die 116 for holding the blank 120 during the dwell of slide 30.

The blank is supported from below by the blank holder ring 40, which is shown in Fig. ll as having a blank holder plate 121 belted thereto at 122 and in turn supporting the lower blank holding die 123. ln presses of the usual construction wherein the lower blank holding assembly is rigidly supported in the bed, it is sometimes found that when the lower slide makes its upwardly directed working stroke to execute a reverse draw, the forming pressure which it develops tends to raise the upper blank holding parts, with the result that the desired holding pressure on the blank is not maintained, and this in turn may result in wrinkling or otherwise spoiling the work. In order to prevent this result and to maintain proper holding pressure on the blank throughout the forming operations thereon, the present invention provides a yieldable support for the lower blank holding assembly which is so constructed and arranged that the blank holder ring can automatically accommodate itself to movements of the upper blank holding parts in such manner as to maintain the proper holding pressure on the blank throughout the forming operations of the other slides.

Referring particularly to Figs. 6 to 8, the blank holder ring 40 is directly supported on a plurality of beams 125 which extend transversely across the bed below the lower slide and through slot openings 126 in the front and

back portions

21 and 22 of the bed, two of these beams being shown. The beams 125 are of lesser vertical extent than the slots 126 so that they can have corresponding vertical movement in these slots, and the beams are normally supported above the bottoms of the slots in suspended relation with the bed by means of tie rods 130. At the lower end of each tie rod 130 is a sleeve 131 which extends from the slot 126 to below the bed and which is of somewhat greater axial length than the distance from the bottom of slot 126 to the lower edge of the bed. The sleeve 131 is slidable in the bed and is held on the tie rod by a nut 132, and with the upper end of each sleeve extending into the slot 126, it will be seen that the beams 125, and hence the entire lower blank holding assembly are supported on the upper ends of these sleeves.

The upper ends of the tie rods 130 are secured to the bed by an adjustable connection indicated generally at 133 and shown in detail in Figs. 6 and 8. The upper end of each tie rod 130 is threaded in the hub of a gear 135 supported on a bearing 136 set in a receiving recess in the upper part of the bed. The gear 135 meshes with a gear 137 on a shaft 138 which also carries a worm gear 140 meshing with a worm 141 on a shaft which extends outwardly through the housing or cover 142 and is provided with a' non-circular end portion 143 for receiving an operating handle or crank. It will be seen that rotation of this shaft will result in rotation of gear 135 to cause threaded adjusting movement of tie rod 130 and resulting vertical adjustment of beams 125 and the blank holding assembly supported thereby.

With the lower blank holding assembly thus yieldably supported by the bed, when the upper slide descends against the sheet on the lower blank holder die 123, it will apply pressure through the blank holder ring 40 and the beams 125 to the tie rods 130, placing these rods in tension so that they are permitted to stretch as desired to give the proper initial holding pressure on the sheet. If the lower blank holding assembly were rigidly supported in the bed, the upward stroke of the lower die slide would tend to urge the upper blank holding parts upwardly, with resulting relaxation of the holding pressure on the sheet. However, since with the present construction the tie rods 130 are elongated in tension while supporting the downward pressure of the upper blank holding parts, they are able to recover from their elongation upon upward movement of the upper blank holding parts in response to the stroke of the lower slide, and in this way they will maintain both sets of blank holding parts in the desired holding relation on the sheet.

The drive for the lower slide 35 also originates from motor 44 through crank shaft 66. Referring to Figs. 3, 5 and 7, the crank shaft 66 includes a centrally located crank portion 150 on which is journaled the upper end of a connecting rod 151 having its lower end pivoted on a pin 152 carried by a member 153 mounted for vertical sliding movement in brackets 155 bolted to the lower edges of a pair of beams 156 which extend across the bed below slide 35 and are bolted to the

bed portions

21 and 22. Two pairs of links 160 are pivoted to the upper part of sliding member 153 and have their other ends pivoted to bell crank levers 161 mounted for rocking movement on pins 162 each carried by an adjacent pair of

beams

156 and 68. Links 165 are pivoted at one end to the levers 161 and at the opposite ends to bell crank levers 166 mounted on rock shafts 167 journaled in the

beams

68 and 156, there being two pairs of these levers and rock shafts.

A connecting rod 170 is pivoted at its lower end to each of the levers 166 and has its upper end adjustably connected with the lower slide 35 to reciprocate this slide in response to the rocking movement of lever 166, there being four connecting rods 170. The upper end of each connecting rod 170 is pivoted in the bifurcated lower end of an adjusting screw 171 threaded in a cylindrical nut 172 supported in a housing portion 175 of the slide 35. An adjusting motor is supported by a bracket 131 bolted to slide 3S, and this motor operates through gears indicated generally at 182 and 183 to drive a worm gear 185 in each of the housing portions 175 which meshes with worm teeth in the circumference of each nut 172. Thus when the motor 180 is operated, it will rotate the nuts 172 to raise or lower the slide 35 on the adjusting screws 171 as desired.

Fig. 5 shows the position of the toggle linkages and associated parts for operating slide 35 in their relative positions corresponding to the lower dead center position of this slide. As the crank shaft 66 is rotated, it will force the connecting rod 151 and sliding member 153 downwardly, and this will in turn draw the links 160 downwardly to cause rocking movement of levers 161. This movement will be transmitted through the links 165 to the levers 166 to cause the latter to rock with shafts 167, thus forcing connecting rods 170 upwardly and this torce is transmitted to screws 171, placing them under compression and thus effecting the working stroke of slide 35. The arrangement of eccentrics and linkages is such that slide 35 operates in timed relation with the stroke of outer slide 30 and is caused to dwell for a prolonged interval coincident with the latter portion of the dwell of slide 30, as indicated by the curve B in Fig. l2. Slide 35 is also shown as provided with a counterbalance cylinder 191B which is supported by the beams 68 in the center of the bed and has a cooperating piston 191 and piston rod 192 secured to the lower part of slide 35, and slide 35 is guided as indicated at 195 for the desired sliding movement in blank holder ring 40.

The inner slide 33 executes its working stroke during the coincident dwell periods of the

slides

30 and 35, and as stated, this slide 33 and the driving mechanism therefor are wholly supported and carried by the outer slide 30. The driving motor 200 (Figs. 2 and 9) for the inner slide is mounted on a bracket 202 supported by

beams

203 and 204 which extend across the top of slide 30 and are bolted thereto similarly to the

beams

103 and 104. The drive pulley 205 of motor 200 is connected through belts 206 with the sheave portion of a flywheel 207 on a drive shaft 210 supported in

brackets

211 and 212 mounted on the beam 204 and the

beams

103 and 104, respectively. A clutch and brake assembly for drive shaft 210 is indicated generally at 213, and this shaft 210 carries a drive pinion 215 meshing with a gear 216 secured on the hub of another gear 217 on a pin or shaft 218 supported by the

beams

103 and 113. The gear 217 in turn meshes with a large gear 220 on the inner slide crank shaft 222, which is supported by bearings secured to the lower edges of each of the

beams

103, 104, 113, 203 and 204.

The crank shaft 222 includes a pair of eccentric portions 225 located between the

beams

103 and 104 and between the

beams

203 and 204, respectively, and a connecting rod 236 is journaled ou 63.611 Qf the, eccentrics 225 and extends downwardly therefrom. The lower end of each connecting rod 230 is provided with an adjustable connection to the inner slide 33. As shown in Fig. 10, the lower end of the connecting rod is pivoted in the bifurcated upper end of an adjusting screw 232 similar to the adjusting screws 171 in the lower slide. Each adjusting screw 232 is threaded in a cylindrical nut 233 secured within a housing portion of slide 33 by a cap 234. An adjusting motor 2d@ is mounted on a boss portion 241 of slide 33, and it is connected through the gears with a shaft ZSSS carrying worm gears (not shown) which mesh with the peripheral worm teeth on each of the nuts 233. lt will accordingly be seen that the inner slide 33 is thus suspended by means of the connecting rods 23@ from the crank shaft 222, and that the crank shaft and drive motor therefor are wholly supported by the outer slide 3l?. The slide 33 is thus carried by slide 30 during the stroke of the latter slide, and the clutch-brake assembly 213 can be energized by drive shaft 222 and cause slide 33 to execute its working stroke in desired sequence with the stroke of slide 3G. The adjustable connection between slide 33 and the connecting rods 230 provides for varying the relative positions of slides 3l) and 33 in accordance with desired operating conditions. It will also be noted that slide 33 is provided with two counterbalance cylinders 25@ supported on slide 33 and cooperating with pistons 251 on piston rods 252 which are secured to and extend downwardly from the beams 163 and 203.

ln the operation of the press, with the motors 44 and running continuously, their respective clutches and brakes may be operated as desired to control the sequence of movement of the several slides, and Figs. ll to 13 illustrate a complete operating cycle of the press. At the start of the cycle, the outer slide 30 will be in its upper dead center position shown in Figs. 1 to 3, and the inner slide 33 will similarly be in its upper dead center position within slide 30. The lower slide 35 will be in substantially its lower dead center position as indicated in Fig. 5. The sheet or blank 12u is set on the lower blank holder die 123, and the slide 30 descends as described to its dwell position in which the upper blank holder die 116 cooperates with die 123 to grip the blank. In the initial adjustment of the press, the tie rods 31 and 13? are set in such relation to the thickness of the blank that there will be limited elongation of rods 130 under pressure from slide 3i) as the slide reaches its lower dead center position.

rl`he lower slide 3S begins its upward stroke after slide 3l? has begun to move downwardly, so that the dies 269 carried by slide 35 lirst come into contact with the blank after slide Till begun to dwell and thus execute their forming operation on the blank during the dwell of slide if this forming operation performed by the lower slide causes upward movement of slide 30 and die 116, the tie rods lltl will be free to recover from the elongation initially imparted thereto so that they will hold the lower blank holding parts in proper holding relation with die 116 to maintain the desired holding pressure on the blank as slide completes its working stroke and also during the subsequent working stroke of the inner slide 33.

The lower slide 35 also dwells after it has completed its upward stroke, as shown by curve E, and during the resulting coincident dwells of both

slides

30 and 35, the clutch-brake assembly 213 for the inner slide 33 is actuated to effect the working stroke of slide 33. As shown in Fig. ll, the upper dies 261 are operated by slide against the dies 262% on slide 35 through pressure pins extending through the receiving holes in bolster 11@ from the pressure plate 263 secured to slide 33. The slide 33 completes its downward stroke near the end of the dwells of the other two slides, as indicated by the vertical line 265 in Fig. l2, and it will accordingly be seen that Fig. ll represents the relative positions of the slides at the point in the .operating cycle of the press represented by the line 265 in Fig. l2. Thereafter the three slides return to their starting positions in preparation for the next cycle of the press.

Fig. 13 illustrates diagramrnatically electrical controls for eitecting the above cycle of the press, these controls being similar to those shown in Byerlein Patent No. 2,073,239, issued March 9, 1937, and assigned to the same assignee as this application. As shown, the starting control 27@ completes an energizing circuit for the operating coils 53a and 54a of the clutch 53 and brake 54 respectively, to initiate the cycle of rotation of main crank shaft 6o. The energizing circuit for

coils

53a and 54a may be held closed for the remainder of the cycle by means such as a switch 271 operated by a cam 272` driven in directly coupled relation with crank shaft 66 as indicated at 273, with these parts being incorporated in a controller indicated generally at 275 (Figs. l and 13). At the end of the cycle the low point of the cam 272 comes opposite the switch 271 which then deenergizes the clutch 53 and applies brake Sal. Energizing of the operating coil 213er of the clutch-brake assembly 213 for the inner slide 33 may be effected in timed relation with the movements of the other slides by means such as a switch 23@ operated by a cam 281 driven similarly to the cam 272 in directly coupled relation with the main crank shaft 66, with this switch and cam also being incorporated in the controller 275. Deenergiziug of the coil 213e at the end of the cycle may be effected by means such as a limit switch 232 incorporated in a controller indicated generally at 285 (Figs. 9 and 13) and operated by a cam 286 driven as indicated at 2&7 in directly coupled relation with the upper crank shaft 222.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. In a sheet metal drawing press comprising a frame structure, a blank holder slide mounted for reciprocatory movement on said frame, actuating means mounted on said frame for moving said slide from an inoperative position to a clamping position, for causing a dwell of said slide, and thereafter returning said slide to its inoperative position, motor means for operating said actuating means, a draw slide mounted for reciprocatory movement in said blank holder slide, a separate actuating means mounted on said blank holder slide and connected with said draw slide for moving said draw slide with said blank holder slide between said inoperative and said clamping positions thereof, and with. respect to said blank holder slide for reciprocating said draw slide while said blank holder slide is in its dwell, clamping position for performing a drawing operation, and separate motor means mounted on said blank holder connected to drive said second actuating means.

2. In a sheet metal drawing press comprising a frame structure, a blank holder slide mounted for reciprocatory movement on said frame, actuating means mounted on said frame for moving said slide from an inopera tive position to a clamping position, for causing a dwell of said slide, and thereafter returning said slide to its inoperative position, motor means for operating said actuating means, a draw slide mounted for reciprocatory movement in said blank holder slide, a separate actuating means mounted on said blank holder slide and c011- nected with said draw slide for moving said draw slide with said blank holder slide between said inoperative and said clamping positions thereof, and with respect to said blank holder slide for reciprocating said draw slide while said blank holder slide is in its dwell, clamping position for performing a drawing operation, separate motor means mounted on said blank holder slide, clutch means for connecting said motor means to said second actuating means.

3. In a sheet metal drawing press comprising a frame structure, a blank holder slide mounted for reciprocatory movement on said frame, actuating means mounted on said frame for moving said slide from an inoperative position to a clamping position and causing a dwell of said slide in said clamping position and for thereafter returning said slide to its inoperative position, motor means for operating said actuating means, a draw slide mounted for reciprocatory movement in said blank holder slide and for movement therewith during said movement of said blank holder slide, and drive means wholly carried and supported by said two slides mechanically separately from said frame and including a motor mounted on one of said slides and means forming a driving connection between said motor and the other said slide for reciprocating said draw slide while said blank holder slide is in said clamping position to perform a drawing operation.

4. In a sheet metal drawing press comprising a frame structure including a bed, a blank holder slide mounted for reciprocatory movement on said frame above said bed, actuating means mounted on said frame for moving said slide from an inoperative position to a clamping position and causing a dwell of said slide in said clamping position and for thereafter returning said slide to its inoperative position, a second action slide mounted for reciprocatory movement in said bed in the opposite direction from said blank holder slide, actuating means mounted in said bed for operating said second action slide with a dwell in its movement coincident with a portion of said dwell of said blank holder slide, motor means for operating both of said actuating means, a third action slide mounted for reciprocatory movement in said blank holder slide and for movement therewith during said movement of said blank holder slide, drive means wholly carried and supported. by said blank holder and third action slides mechanically separately from said frame and including a motor mounted on one of said pair of slides and means forming a driving connection between said motor and the other said slide for reciprocating said third action slide in said blank holder slide, and control means for causing said drive means to reciprocate said third action slide during said coincident dwells of said blank holder and said second action slides.

References Cited in the tile of this patent UNITED STATES PATENTS 47,246 Powers Apr. 1l, 1865 308,098 Robertson Nov. 18, 1884 1,664,990 Oehmig et al Apr. 3, 1928 2,018,576 Rode et al. Oct. 22, 1935 2,133,161 Colbert Oct. 11, 1938 2,259,882 Glasner Oct. 21, 1941 2,289,584 MacMillin et al July 14, 1942 2,301,225 Muller Nov. 10, 1942 2,331,491 Menkin Oct. 12, 1943 2,366,172 Bohn Jan. 2, 1945 2,429,062 Johansen Oct. 14, 1947 FOREIGN PATENTS 450,157 Great Britain July 10, 1936