US2888894A

US2888894A - Press

Info

Publication number: US2888894A
Application number: US571122A
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: 1956-03-07
Publication date: 1959-06-02
Anticipated expiration: 1976-06-02

Description

6 Sheets-Sheet 1 June 2, 1959 A. A. BYERLEIN PRESS original Filed Deo. 1e. 1949 ATTOR N EYS June 2, 1959 A. A. BYERLEIN PRESS 6 Sheets-Sheet 2 Original Filed Dec. 16, 1949 0 25 5 9N o0 A MMHHMHWWMWWH H nu' u ATYORNEYS June 2, 1959 A. A. BYERLEIN 2,888,894

PRESS original Filed Dec. 1e, 1949 e sheets-sheet s ATTORN EVS June 2, 1959 A. A. BYERLEIN PRESS 6 Sheets-Sheet 4 Original Filed Dec. 16, 1949 June 2, 1959 A. A. BYERLEIN 2,888,894

l PREss original Filed Deo. 16. 1949 e sheets-sheet s 1oz` 101104 99 10s zzo 203 204 1oz El -9 `10o 205 zoo 25o sa 51 o 41 252 zas ATTOR N EYS June 2, 1959 A. A. BYERLEIN 2,888,894

PRESS Original Filed Dec. 16. 1949 I 6 Sheets-Sheet 6 ATTORNEYS r g 2,888,894 lee Patented June 2, 1959 PRESS Arthur A. Byerlein, Detroit, Mich., assignor, by mesne assignments, to Baldwin-Lima-Hamilton Corporation, a corporation of Pennsylvania Original application December 16, 1949, Serial No. 133,450, now Patent No. 2,750,909, dated .lune 19, 1956. Divided and this application March 7, 1956, Serial No. 571,122

Claims. (Cl. 113-46) This invention relates to presses, and more particularly to drawing, forming and stamping presses such as are used for forming metal parts in the manufacture of automobile bodes and parts thereof, and the like.

This application is a division of application No. 133,- 450, iiled December 16, 1949, now Patent No. 2,750,909.

The invention has particular relation to multiple action presses having two or more slides which execute working strokes on the sheet or 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, Ibut it 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 insuicient holding pressure. This 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.

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.

In the drawings- Fig. 1 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. 1, 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. l0; v

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. l2 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 ot 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, the bed ends 20 also including projections 23 which are adapted to rest on suitable supporting columns 24 below the floor 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 thev 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 trame uprights 26. The inner die slide 33 is ment 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 lwithin 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 40 supported by the bed to hold 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 perform 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. 12, 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 floor below the press, and it has a drive pulley 46. Drive belts 47 connect pulley 46 with the sheave portion of a ywheel 5G 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 60 are pinions 62 engaging the large gears 65 at each end of the main crank shaft 66, which is journaled in the bearing brackets 67 (Figs. l 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 slidingr movement in the end portion 28 of the bed. Two links 76 are pivotally connected at one end to the opposite sides of the sliding member 75 `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 S2 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 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 85 is pivoted to an upstanding yoke portion 86 of a beam 88.

The lower ends of the tie rods 31 for the outer slide 30 are secured to the beams 88 to operate thev 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 (Figs. 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 4 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 connected to the slide 30 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 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 95 on a shaft 96 driven by an adjusting motor 99 through suitable gearing indicated generally at 100, 101 and 102, the motor 99 being supported by

beams

103 and 104 which extend across the upper part of slide 30 and are bolted thereto. Thus when motor 99 is operated, the nuts 93 are rotated and act through their threaded connections with sleeves 98 to raise or llower the slide 30 on the tie rods, a similar adjustable connection being illustrated in Byerlein Patent No. 2,378,062, issued June l2, 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 rotated, the associated eccentric strap 71 moves downwardly and pulls the operating member 7S 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 Sti to cause similar rocking movement of levers 81. As a result, the linkages composed of the lever arms 83 and the elongated links 85 are straightened out as shown in dotted lines in Fig. 2 to produce a downward thrust on beams 88, with accompanying tension on tie rods 31 to pull the slide 30 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 opposite 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. 1l) having the usual holes 111 therethrough for receiving pressure pins. The bolster 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. In addition, the bolster may be secured at its periphery to the peripheral ange at the lower end of slide 30 as indicated at 115 in Fig. 11, and the bolster is also shown in Fig. l1 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. 1l as having a blank holder plate 121 bolted thereto at 122 and in turn supporting the lower blank holding die 123. In 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 forming 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. lt 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 Iresulting 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. 30 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 35 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 7J the crank shaft 66 vincludes 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 tothe levers 161 and at the opposite ends to bellV 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 181 bolted to slide 35, and this motor operates through gears indicated generally at 182 and 183 to drive a worm Igear 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 Ilower 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 force 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 portionof the dwell of slide 30, as indicated by the curve B in Fig. 12. Slide 35 is also shown as provided with a counterbalance cylinder 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 230 is journaled on each of the eccentrics 225 and extends downwardly therefrom. The lower end of each connecting rod 230 is provided with an adjust-v able connection to the inner slide 33. As shown in Fig. 10, the lower end of the connecting rod is pivotedin 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 240 is mounted on a boss portion 241 of slide 33, and it is connected through the gears 242 with a shaft 243 carrying worm gears (not shown) which mesh with the peripheral worm teeth on each of the nuts 233.

It will accordingly be seen that the inner slide 33 is thus suspended by means of the connecting rods 23h from the crank shaft 222, and that the crank shaft and drive motor therefor are wholly supported by the outer slide 30. The slide 33 is thus carried by slide 3h during the stroke of the latter slide, and the clutch-brake assembly 213 can be energized to drive shaft 222 and cause slide 33 to execute its working stroke in desired sequence with the stroke of slide 30. The adjustable connection between slide 33 and the connecting; rods 230 provides for varying the relative positions of

slides

30 and 33 in accordance with desired operating conditions. It will also be noted that slide 33 is provided with two counterbalance cylinders 256 supported on slide 33 and cooperating with pistons 251 on piston rods 252 which are secured to and extend downwardly from the

beams

103 and 203.

In the operation of the press, with the motors 44 and 2h13 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 3G 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 120 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 131) are set in such relation to the thickness of the blank that there will be limited elongation of rods 130 under pressure from slide 36 as the slide reaches its lower dead center position.

The lower slide 35 begins its upward stroke after slide 30 has begun to move downwardly, so that the dies 266 carried by slide 35 first come into contact with the blank after slide 30 has begun to dwell and thus execute their forming operation on the blank during the dwell of slide 30. if this forming operation performed by the lower slide causes upward movement of slide 30 and die 116, the tie rods 13G rwill 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 35 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 oy curve B, 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 eect the working stroke of slide 33. As shown in Fig. ll, the upper dies 261 are operated by slide 33 against the dies 260 on slide 35 through pressure pins 262 extending throughL the receiving holes in bolster' 11b 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 operatingY 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 diagrammatically electrical controls tor etfecting 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 270 completes an energizing circuit for the operating coils 53a and 54g of the clutch 53 and brake 54 respectively, to initiate the cycle of rotation of main crank shaft 66. The energizing Vcircuit for coils 53a and 54a may be held closedfor 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 54. Energizing of the operating coil 213a 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 280 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. Deenergizing of the coil 21341 at the end of the cycle may be effected by means such as a limit switch 282 incorporated in a controller indicated generally at 285 (Figs. 9 and 13) and operated by a cam 286 driven as indicated at 287 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 dened in the appended claims.

What is claimed is:

l. A sheet metal drawing press comprising a frame structure including a bed, a blank holder ring located in said bed, a blank holder slide mounted for reciprocaytory movement on said frame above said bed, actuating means for moving said slide from an inoperative position to a position in clamping relation with said blank holder ring 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 for operating said second action slide during said dwell of said blank holder slide, means for yieldably supporting said blank holder ring in a normal position on said bed to provide for limited downward movement of said ring from said normal position under the pressure of said blank holder slide in said clamping position thereof, and said supporting means including tie rods supporting said ring in suspended relation with said bed for limited elongation under the tension developed by the clamping engagement of said blank holder slide with said ring to eiect automatic return movement of said ring toward said normal position upon upward movement of said blank holder slide under the pressure of said second action slide to maintain said blank holder slide and said ring in said clamping relation throughout the stroke of said second action slide.

2. 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, support means in said bed adapted to support a blank from below in blank holding relation with said slide, means for operating said slide to a position in blank holding relation with said support means and causing a .dwell of said slide in said blank holding position, a sec- I ing said support means, means connecting the upper ends of said tie rods to Vsaid bed, and means connecting the lower ends of said tie rods to said support means to provide for placing said tie rods in longitudinal tension under the pressure of said blank holder slide on said support means in said blank holding position thereof.

3. 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, support means in said bed adapted to support a blank from below in blank holding relation with said slide, means for operating said slide to a position in blank holding relation with said support means and causing a dwell of said slide in said blank holding position, a second action slide mounted for reciprocatory movement in said bed in the opposite direction from said blank holder slide, means for operating said second action slide during said dwell of said blank holder slide, a plurality of beams extending across said bed below and in supporting relation with said support means, a plurality of tie rods connected at their lower ends to said beams and at their upper ends to said bed to provide for elastic deformation thereof under the pressure of said blank holder slide on said support means in said blank holding position thereof, and means for guiding said tie rods to maintain said blank holder slide and said support means in said blank holding relation.

4. 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, support means in said bed adapted to support a blank from below in blank holding relation with said slide, means for operating said slide to a position in blank holding relation with said support means and causing a dwell of said slide in said blank holding position, a second action slide mounted for reciprocatory movement in said bed in the opposite direction from said blank holder slide, means for operating said second action slide during said dwell of said blank holder slide, a plurality of beams extending across said bed below and in supporting relation with said support means, a plurality of tie rods connected at their lower ends to said beams, means connecting the upper ends of said tie rods to said bed to provide for elastic deformation thereof under the pressure of said blank holder slide on said support means in said blank holding position thereof, and means for adjusting said connecting means to establish the normal vertical position of said beams in said bed.

5. 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, support means in said bed adapted to support a blank from below in blank holding relation with said slide, means for operating said slide to a position in blank holding relation with said support means and causing a dwell of said slide in said blank holding position, said operating means including a drive mounted in said bed and tie rods connecting said drive with said blank holder slide and arranged to be placed in longitudinal tension during said operation of said slide to said blank holding position and said dwell, a second action slide mounted for reciprocatory movement in said bed in the opposite direction from said blank holder slide, means for operating said second action slide during said dwell of said blank holder slide, a plurality of tie rods located within said bed for supporting said support means, means connecting the upper ends of said tie rods to said bed, and means connecting the lower ends of said tie rods to said support means to provide for placing said tie rods in longitudinal tension under the pressure of said blank holder slide on said support means in said blank holding position thereof. t

References Cited in the tile of this patent UNITED STATES PATENTS 2,018,576 Rode et al. Oct. 22, 1935 2,120,356 Glasner June 14, 1938 2,259,882. Glasner Oct. 21, 1941 2,350,884 Ernst June 6, 1944 2,429,062 Johansen Oct. 14, 1947 2,750,909 Byerlein v June 19, 19,56

UNITED STATES PATENT oFFTCE CERTIFCATE GF CQRRC'NGN Patent No.1 2,888y894 51m@ 2;, Arthur Byerlein It is hereby certified that error appears in the printed specification of' the above numbered patent .requiring correction and that the said Letters Patent should readas corrected below.

Column 5, line l, for "maintain the forming" read maintain 'the proper Signed and Sealed this 3rd day of November 1959..

(SEAL) Attest:

KARL H., AXLINE RGBEBT C. WATSON Atteeing Ocer Commissioner of Patents