US2514830A - Metal stretching and contour forming machine - Google Patents

Description

7 Sheets-Sheet 1 c. J. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE INVENTOR.

CYRIL J.BATH

BY M, v/Qcuf.

ATTORNEYS July 11, 1950 Filed Feb. 17, 1944 mv N mv July 11, 1950 c. J. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE Filed Feb. 17, 1944 7 Sheets-Sheet 2 July 11, 1950 c. J. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE 7 Sheets-Sheet 5 Filed Feb. 17, 1944 INVENTOR.

CYRIL J. BATH GM, ATTORNEYS July 11, 1950 c. J. BATH 2,514,830

METAL STRETCHING AND CONTOUR FORMING MACHINE Filed Feb. 17, 1944 7 Sheets-Sheet 4 290 we 27 l6 I7 I 300 I l 1 i H O 4a 49 INVENTOR.

CYRIL J. BATH om gww ATTORNEYS C. J. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE Filed Feb. 17, 1944 July 11, 1950 7 Sheets-Sheet a .lllalln (fig. 7

INVENTOR. CYRIL J. BATH ATTORN EYS July 11, 1950 0.]. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE Filed Feb. 17, 1944 7 Sheets-Sheet 6 INVENTOR.

CYRIL J. BATH ATTORNEYS July 11, 1950 c. J. BATH METAL STRETCHING AND CONTOUR FORMING MACHINE 7 Sheets-Sheet '7 Filed Feb. 17', 1944 INVENTOR.

CYRIL J. BATH Y I ATTORNEYS Patented July 11, 1950 METAL STRETCIIING AND CONTOUR FORMING MACHINE Cyril J. Bath, Chagrin Falls, Ohio, assignor to The Cyril Bath Company, Cleveland, Ohio, a

corporation of Ohio Application February 17, 1944, Serial No. 522,700

18 Claims.

This invention relates to a metal working machine for forming -stock pieces such as rods, bars, tubes, pipes, sheets and shapes into regularly or irregularly curved or contoured forms. The subjecting of such a stock piece of metal to a stress approaching, or slightly exceeding, its elastic limit, and conforming it to a master shape or die, has heretofore been accomplished by various types of machines, apparatus, and special tools and jigs. Such machines have usually been designed to accomplish the specific metal shaping design at hand, or for a particular type of stock or blank form.

The general object and nature of my invention is to provide a contour forming machine which is capable of operating equally well upon rods, bars, tubes, pipes, sheets and shapes, and in which a practically unlimited range of contours can be produced.

The forming of metal to a contoured master shape while it 'is stressed to its elastic limit has in practice been found to be arather diflicult operation, particularly in the case of metals whose elastic limit and ultimate strength are of relatively close values. As a piece of metal stock, such as a bar or angle shape, is placed under a tension which is initially determined to be its elastic limit, and then formed around a contoured shape, it is often quite likely that stresses will be imparted to the metal during the subsequent forming operation which exceed both the elastic limit and the ultimate strength whereupon the material is fractured and the entire workpiece ruined.

It is, accordingly, a further object of my invention to provide a metal tensioning means which is operative to apply the'tensioning force at all times tangent to the surface of the forming die. To the accomplishment of this objective, .I provide a rotatable die supporting table and a power cylinder and piston for tensioning the workpiece, such cylinder being pivotally mounted upon an axis parallel to that of the table whereby it maypivot or swing, thus permitting the laid on workpiece to occupy a tangent position with respect to the formingdie, and wherein the direction of application of the tensioning force (through the longitudinal axis of the pressure cylinder) is likewise atall times in alignment with such tangent. The rate at" which the tensioned workpiece is laid upon an irregularly curved or contoureddie often variesthroughout the extent of the forming operation. In order to compensate for this factor, while simultaneously maintainingia uniform tensioning stress, 'myinvention 2 a also provides an automatic pressure control system for maintaining the same tensioning' force in the pressure cylinder, regardless of the rate at which its piston might be caused to move inwardly or outwardly during the working cycle.

In certain contour forming operations, I have found it desirable to apply a compressive forming force in addition to the tensioning stress on the workpiece. In other words, while the work piece which is being stretched to its elastic limit is laid upon the forming die, it is also desirable in certain instances simultaneously to exert a compressive ironing or rolling force against the workpiece, such as, for example, when negotiating corners and curves of relatively small radius, or forms having reverse curvatures.

Additional objects and advantages of my invention shall become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. 1 is a side elevational view of a machine embodying the principle of my invention;

Fig. 2 is a top plan view thereof;

Fig. 3 is a perspective view thereof; Y Fig. 4 is a partial perspective view similar t Fig. 3, but showing the machine operating upon sheet stock;

Fig. 5 is a diagram representing a hydraulic pressure control system for the pressure cylinder; v

Fig. 6 is a detailed, sectional view of a die table limit stop abutment block;

Fig. 7 is a diagrammatic view illustrating the relative positions of movement of the die table and tensioning cylinder during the contour forming working cycle;

' Fig. 8 is a view similar to Fig. 7 but showing the workpiece being formed to a different contour;

Fig. 9 is a top plan view of a modified form of construction for mounting the pressure cylinder and in which the latter is adapted for both tension and compression operation;

Fig. 10 is a partial side elevation of Fig. 9;

Fig. 11 is a sectional view taken upon a'plane normal to Fig. 10 andsubstantially along line ||-l l thereof;

Fig. 12 is a top plan view of another modified form of machine embodying the principle of my invention, such machine being adapted for combined tensioning and compressing operation upon the workpiece;

Fig. 13 is a side elevational view of a portion of Fig. 12; and

Figs. 14 and are diagrammatic views similar to those of Figs. '7 and 8, but illustrating the machine, as set up with a compression holding cylinder on the die table, and having a die Of reversed curvature contour.

Now referring more particularly to Figs. l-3, incl., the machine shown therein comprises'a supporting and housing base I adjacent whose lefthand end the die supporting table 2 is rotatably mounted. The table 2 is carried upon the vertical shaft -3 which in turn is journaled at the upper and lower bearings 4 and 5, respectively, in the base I. Thrust bearing plates are rovided at 6 for rotatably carrying the weight of the table 2.

A large ring gear I is carried on the underside of the table 2, as by the screw bolts 8 and is adapted to b engaged b the small pinion gear 9 which in turn is carried upon the vertical shaft of the one way drive or self-locking worm and gear unit ID. The drive pulley H on the unit It! is connected by means of the belt I2 through the pulley I3 on the variable speed transmission I4, the latter in turnbeing driven through the electric motor I5.

The hydraulic-pressure cylinder I6, carrying the piston rod IT is fastened at its end plates 58 and I9 to the elongated base plate 29. The plate '20 is in turn secured to the disc plate or table 2! which is rotatably mounted by means of the stub shaft 22 journaled in the circular supporting plate 23. The table 2| has a circumferential shoulder as indicated at 24, which is engaged by the retaining ring 25. The-cylinder 16 is thus pivotally mounted, in a direction transverse to its longitudinal axis, upon the flat top wall portion 26 of the base I.

Referring to Fig. 2, it will be seen that the axes of the table 2, and of the table 2 I, as represented by the shafts 3 and 22, respectively, and that the axis of the pinion gear 9, are all in alignment with respect to the bas I. Thus, the rotating driving force imparted from the'pinion gear 9 to the table -2 is in alignment with the reaction forces transmitted to the shaft 3, as well as being in alignment with the reaction forces transmitted from the cylinder IE to the shaft 22; all of such forces being received at the longitudinal mid plane of the base i wherethe maximum strength of the latter is availableto withstand them.

The piston rod I I carriesan L-shaped pedestal 2'! whose horizontal or bottom leg engages in the dovetail slideway 28on the base plate 20. As will be seen from Fig. 3, the pedestal Z'Iis adapted to mount a workpiece clamp'29 in the desired vertical position, being provided with undercut grooves (see Fig. 1) whereby such clamp may be adjustably secured thereto. The other end of the workpiece W is held in the clamp 30 on the end of the forming die 3i which inturn is bolted to the top of the table 2. Said die is laterally facing, i. e., the face thereof with which the workpiece contacts is disposed transversely of lines radial to the axis of the table.

In Fig. 4, the machine is shown as set up for operating upon a workpiece Wswhich is a relatively wide piece of sheet stock. In this case, the vertical leg of the pedestal 2'! is utilized to give firm support to the relatively long clamp 29a.

A relatively high or wide die 3'11, together with the clamp 303., which grips the other end of the workpiece, forms the latter as the table 2 is rotated and tension is applied by the hydraulic cylinder Hi. It will be seen that the slideway 28 cooperates with the bottom leg of the 'L-shaped pedestal 21 t-omaintain the vertical leg portion thereof in proper alignment during the movement of the piston rod I1, particularly when operating upon sheet stock, such as the workpiece Wa. This in turn counteracts any tendency 0f the clamp 29a to become cocked or misaligned during the contour forming operation and coincidentally, prevents the setting up of unequal stresses and strains in the workpiece.

An electric drive motor 32, contained within the housing I, drives the hydraulic pump 33, which is connected to the cylinder I6 by means of the hydraulic system diagrammatically illustrated in Fig. 5. The pump 33 delivers pressure to the pressure regulating valve 34 which in turn is connected to the line 35 to the distributing valve 36. The pressure regulating valve 34 is of the adjustable type, as well known to those skilled in the art, so that its delivery output pressure may be set at a predetermined value, indicated upon the pressure gauge. The distributing valve 36 is operated by means of a lever 38, suitably accessible on the exterior of th base housing I and is adapted alternatively to connect the pressure line 35 to the lines 39 and 49 leading to the rod and head end respectively of the cylinder It.

The exhaust outlet of the pressure regulating valve is connected through the line 4| to the flow control valve 42 which in turn is connected to the exhaust line 43 leading back to the pump reservoir 44.

The actuation of the drive motor I5 is controlled by an operating lever 45. A limit switch 46 is connected in series with the-motor switch actuated by the lever 45 and has an operating lever 41 extending into the peripheral groove 48 on the side of the table 2. Adjustably locatable limit stop abutment blocks 49 are adapted to be engaged in the groove 48. As seen from Fig. 6, the abutment blocks 49 are composed of the two wedge-shaped halves 50 and 5| which are drawn together by the cap screw 52 and thus caused to grip the top and bottom walls of the groove 48.

The operation of theapparatus as hereinabove described is as follows:

The workpiece is gripped between the clamps 29 and 30, Fig. 3. The table 2, with the forming die block, such as the one indicated at 3! attached to its upper surface, is at first in a position substantially 90 clockwise removed from that shown in Fig. 3, and wherein the workpiece is still in its straight line form. The lever 38 is then operated to introduce pressure to the cylinder I6'and to place the workpiece W under a tension equal to its elastic-limit, asindicated on the pressure gauge -3I,"an'd as determined by the regulation of the pressure regulating valve 34. The lever 45 is then operated to start the drive motor [5 and correspondingly the table 2, to rotate in a counter-clockwise direction whereupon the workpiece is laid on or wrapped around the forming surface of the die 3 I.

As previously described, the driving connections between motor I5 and the table are of one-way or self-locking type, so that rotation of said table will be restrained or braked against slippage under pull of the workpiece when the latte;- is placed under tension in the mannerjust set forth. In other words, rotation of the table at certain stages lines.

of operation is permitted or controlled, rather than produced, by the motor.

At any point in this operation where the tension on the workpiece W and hence the pressure in the rod end of the cylinder 16 exceeds the predetermined setting of' the pressure regulating have to move in the opposite direction '(viz. in-

wardly of the cylinder l6), which might be caused by the particular configuration of the die, the slightest drop in pressure in the cylinder l6 would immediately operate to connect the valve 34 to the line 35, so that the predetermined pres- 1 sure would be maintained in the cylinder [6 in such direction of travel. Thus, the correct tensioning force is exerted by the piston H at all times during the forming operation, viz., rotation of the table 2, and regardless of its relative in or out movement.

As the table 2 rotates to the point where the workpiece W is completely laid on or formed around the die 3|, the limit stop block 49 contacts the finger 41 of the switch 46, stopping the motor l5 and'the rotation of the table 2. As the lever 45 is moved to reverse position to drive the motor l5 and the table 2 in opposite direction, the other limit stop block 49 (see Fig. 2) operates to stop the table 2 at the proper position for receiving another workpiece and repeating the forming operation.

It will be noted that as a result of attaching the one end of the workpiece to the pedestal or slide 21 instead of directly to the end of the piston rod ll, the latter is relieved of all side strain due to changing angularity in the direction of the pull on the workpiece. In other words, inasmuch as said slide is supported in the slideway 28, which is of substantial construction, the strains in question will be taken up by the latter so that the piston and its actuating cylinder need only maintain the necessary longitudinal pull on the workpiece. The operation of such piston and cylinder is accordingly much facilitated and wear thereon greatly reduced.

Figs. 7 and 8 diagrammatically illustrate the operating positions of the machine for different types of contour forming work.. In Fig. '7 the machine is represented as operating upon a die form of substantially uniform curvature. The starting position of both the table 2 and cylinder I6 is indicated in full lines at A, the half-way position at B, and the finishing position at C, the latter two positions being shown in dotted It will thus be seen that'the workpiece W in Fig. '7 is laid on to the forming die in tangent relationship to the contoured surface of the latter, and that the cylinder It takes up pivotal'positions permitting the maintenance of this tangent relationship. It will be seen that the total amount of movement of the piston I1 is relatively small for the length of the workpiece W. In the case of Fig. 7, this movement is unidirectional and substantially uniform from start to finish.

In Fig. 8, the die form is of an irregular degree of curvature. It will be noted that the piston l! in this instance first moves inwardly from the starting position A to the intermediate position slightly outwardly to the final position C. Re-

6 gardless of this irregular of the piston H, the tension exerted upon the workpiece W nevertheless remain uniform and constant throughout the forming operation, due

to the operation of the hydraulic control system hereinabove described.

In the modified form of the machine as shown in Figs. 9-11 inc1., the hydraulic cylinder 60 with its piston is so mounted on the base frame I as to be adjustable to various positions with respect to the axis of the die table 2, while being capable of swinging on its pivotal mounting when its piston is reciprocated for tensioning action, or of being fixedly mounted when its piston is reciprocated for compressive action. The cylinder 60'has its end plates BI and 62 bolted to the base plate 63 which is in turn pivotally mounted to the block nut 64 by means of the stub shaft 65. The nut 64 is held against rotation and adapted to slide along the angle bars 66 and 31 secured to the underside of the top wall of the basel; T

' A rotatable feed screw 38 engages with the nut 64. An elongated slot or opening 69 i provided in the top wall of thebase l to permit the back andforth movement of the nut 64 and of the connecting shaft 65.

" The feed screw 68 is journaled'at each end in the bearing bosses Ill and H and is rotated by suitable means such as by the drive motor 12 conrlected to the pulley 13 mounted on the end of the ieed screw 68.

The end of the base plate 63 supporting the cylinder 6!], opposite to its pivotal mounting at the shaft 65, is supported upon the rollers 14 and 15. As will best be seen from Fig. 9, the axes ofthese rollers are so disposed as to permit the rollers to travel upon the circumference of a circle whose center is the center of the shaft 65.

The cylinder 69 has a piston rod 56 connected tothe mounting pedestal 1'! which, like the previously described pedestal Z'Lhas a bottom horizontal leg engaging in the dovetail slideway in the plate 63.

It will thus be seen, that by'adjusting the positionv of the plate. 63, and the cylinder 6|] on the top. of the base I, thata wide range of forming die sizes on theltable 2 can be accommodated, so

that it ,can be moved up toposition where the pedestal ll overhangs the circumference of the table 12. (as shown by dotted lines in Fig. 9) for working on relatively small dies or for compression work; or it may be moved a substantial distance away from the table 2 for larger dies and for certain long stretching operations. When the cylinder 60. ismoved closest to the table 2, or in the position shown indotted lines in Fig. 9 and employed for compression or rolling operations, it is .locked againstpivotal movement by means of locking bolts 19 and fitting through holes inthebosses 8| and.82, respectively, and through the top Wall of the base i.

Asshownin-Fig. 9, when the cylinder 60 is thus locked against the pivotal movement and employed .for compression rolling operation, the pedestal 11 carries a suitable work contacting .tool such as the double rollers 83 and 84 adapted to contact against the side of the workpiece W being wrapped around the die 85. The rollers 83 and 8,4 are mounted'in the carriage 86 which is pivotally attached as indicated at 81 to the pedestal 'I'l.

-,.In'theform of construction in Figs. 12 and 13, the machine shown therein is adapted to perform combined tensioning and compressionrolling opand reversed movement 2, 51.42, sec

erations on the-same piece of stock. Aswill be seen from Fig. 12; the-baseof the machineis' substantially L-shaped, comprising the legs I a. and In emanating: radially, and in angular-1 p spaced relationship (specificallyat an angle of' 90 as shown in Fig. 12) from the center of'the die tablev 2 The base portion Ia supports the pressure cylinder 59,- for-min-g rolls. Il3- and 8 I, of the sameconstruction as last describedin connection with- Figs. 9-11. The base portion Ib supports the tension: cylinder fili which. is adapted to grip the workpiece=W at the clamp"- III on the end of its piston rod 92. The rod end-casting 93 of the cylinder'SB is mounted in the-slideway 94 of the vertical' column 95. A feed. screw 96, operated by means of the hand crank 91, engages: with the cylinder end casting 93 for movingthe cylinder 9D- todesired vertical positions.

The vertical column 95 is mounted on a table 98iwhich in turn is pivotally supported within the sliding carriage!!!) as shown in dotted lines in Fig. 12. The carriage 99 rides upon the slideways I00. and: Ill Iion thettop of the base portion Ib.. A pinion I02, journaled in; the downwardly projecting leg I03- from the. carriage 99,. engages with the gear rack I04, andis adapted to be operated by the crank I05.

Stopblocks. I06 are. provided at intervals across the top of the base portion Ib and are adapted to be engagedby the lockingtdog lIl'I which fits betwe'emsuch stop blocks and the right-hand front face of the slide carriage 99.

Thus, by operating the pinion I02, the carriage In Figs. 14 and 15, the principle of my invention. is shown as being applied to the contour forming of reverse bends in the stock. Thus, the die I3I will be seen to comprise the convex portion I32 merged with the, concave portion. I33.

which in turn joins with the second convex portion I34 of the die forming. surface. In Fig. 14 theworkpiece W is shown being formed over the convex die surface portion I32, in the same manner as previously described herein. However, when the. die table 2 turns further in a counterclockwise direction with respect to Fig. 14,, the workpiece. W would normally bridge over the reverse bend. or concave die portion I33. Hence, the hydraulic cylinder I35 with its. piston I36 is mounted oppositethe die portion I33, viz., on a line normal to the major chord of the curvature of the portion I33. A male die or pad I3! is carri'ed'on the end" of the piston rod I36; andlwhen the die table 2 reaches a position where the workpiece W tends to contact the high pointsof'both the portions I32and I34, the cylinder I35 is operated'topress theworkpieceW'into the reversed bend" portion. I33,.substantially as shown in Fig. 15. The pad I3! is held in such position as-the die table 2 continues to rotate and thus form the remainder of the workpiece contouraround the convex die portion I34.

Other modes ofapplying the principle of-the invention maybe employed, change being made as regards the detailsdescribed; providedthe fea- 81 tures=stated in any of thefollowin'g claims or'the equivalent of such be employed;

I" therefore: particularly point out and. distinctly'claim as my invention:

1 In a contour forming machine a base, a rotatable tableth'ereon, means to rotate the table, apair of metal forming piston and cylinder as semblages, connecting means respective to and connecting the assemblages with their axes generally. parallel: to-a plane normal to the axis of the table and extending generally toward and awayfrom the table; one assemblage on the base and: the other for rotation with the table, the table-' being. adapted to support a side face die means for supplyingpressure fluid to said one assemblagesoas toyieldably urge its piston in a direction generally away from the table, means for supplying'pressure fluid to the other assemblage' so as to yieldably urge its piston in a predetermined dlreotion: and. means on the piston of saidroneassemblage adapted to be connected to; the endlof: a: workpiece when the workpiece is in contact with. the side face of the die so as to exert tension onzsaid workpiece.

2. The structure according to claim 1 characterizediinathatthe connecting. means of said one assemblage includes a pivot generally parallel to the table: axis andwhich pivot connects said one assemblage-and base so that the said one assemblageis swingable aboutthe axis of the pivot.

3. Thezstructure:accordingto claim 2 characterized inv that the connecting means of said other assemblage constrains. saidother assemblage from swinging movement relative to the table 4. In a contour forming: machine: a base, a rotatable table thereon means tc-rotate the table, azpair ofmetal forming piston and cylinder assemblages, connecting: means respective to and connecting the assemblagesonthe base in angularly spaced relation to each other about the tableaxis andwith their. pistons extending generallytoward andlaway. from the table and their axes generally parallel to a plane normal to the tableaxis, means, for sup-plying fluid under pressure toone assemblage so as to yieldably urge its piston in a; direction generally away from the table, means forsupplying fluid under pressure to the'other assemblage so as to-yieldably urge its piston in a direction generally toward the table said table being adapted to support a side face die for/rotation. therewith, means on the one of the pistons urged generally away from the table adapted to be connected to the end of a w.orkpiece,,when the workpiece is in contact with the-side face ofthedie, so as to exert tension on theworkpiece, and thepiston of the other assemblagerbeing adapted forconnection to a work'- piece. engaging tool.

5; The structure. according to. claim 4 characterized inithat the=connecting means of. said one assemblage includes a pivot parallel to the table axis-andwhich pivot connects said one assemblage and base so that said one assemblage is sWingable-about the axis of the pivot,

6.- In' a contounforming. machine a base, a 1'0- tatable tableuthereon, a side face die supported on.the-table, means to rotate the table, a pair of metal forming piston and cylinder assemblages, connecting means respective to and connecting the: assemblages; with: their axes generally parallel to aplane'normal'to' the axis of the table, one assemblage on the base and the other assemblage on the table-for rotation therewith, said assemblages being positioned: so that the pistons are "movable relatively-toward and away fromthe side face of the die, the piston of one of said assemblages being adaptedto'exert tension onthe end ofa workpiece contacting the side "face of said die andthe piston of the other of said assemblages being adapted to exert metal forming force on the workpiece in a direction generally toward the side face of the die.

75The structure according to claim 6 characterized in that the connecting means of said one assemblage includes a pivot parallel to the table axis and which pivot connects said one assemblage and base so that the said one assemblage is swingable about the axis of the pivot.

The structure according to claim 7 characterizedin'tha't the connecting means of said other assemblage constrains saidother assemblage from swinging movement relative to the table.

: 9."-.Iri a contour forming machine a base, a retatable table thereon, a side face die mounted on said table, means to-rotate the table, a pair of metal forming piston and cylinder assemblages,

connecting means res'pectiveto and connecting the assemblages on the base in angularly spaced 'relation' to each other about the table axis and with their pistons extending generally toward "and away from the table and their axes generally parallel to a plane normal to the tables axis, the piston of; oneassemblage being adapted for connection to the end of a workpiece contacting the face of the-die so as to exert force in a direction :awayfrom the die for tensioning said workpiece contacting said die face, and the piston of the otherassemblage being adapted to exert force on I the workpiece in a direction generally toward the 11. In a contour forming machine a base, a retatable table thereon adapted to support a side face die, a metal forming piston and cylinder assemblage mounted on the base with its axis in a plane generally normal to the table axis and with its axis extending generally toward and away from the table for transverse swinging movement about an axis generally parallel to the table axis, a guide mounted in fixed position relative to the assemblage and swingable therewith about the swinging axis of the assemblage and extending parallel to the longitudinal axis thereof, a tool holder reciprocable in the guide and connected to the piston, means to rotate the table, and means to supply pressure fluid to the cylinder so as to yieldably urge the piston in a direction generally away from the table.

12. In a contour forming machine a base, a rotatable table thereon, means to rotate the table, a side face die on the table, a piston and cylinder assemblage supported on the base with its longitudinal axis in a plane generally normal to the axis of the table, and with its axis extending generally toward and away from the face of the die, clam-ping means secured for rotation with the table and connected for movement with the piston, respectively, for engaging the opposite ends of a workpiece, means for supplying pressure fluid to said assemblage so as to urge the piston in a direction generally away from the die with force to apply sufiicient tension on the workpiece to cause the workpiece to conform substantially to the side face of the die upon release of 10 the workpieceafter the table-has been rotated with said tension applied.

13. The structure according to claim 12 characterized in" that said assemblage is connected to the base for swinging movement about an axis generally parallel to the axis of the table and through an are such that the workpiece held under tension by the piston and lying between the piston and instantaneous line of contact between the workpiece and the side face of the die during rotation of the table is tangent to the side face of the die at said line of contact.

14. A combined stretching and bending machine for bending elongated members into predetermined shapes, comprising a base, a turntable rotatably mounted thereon, a side face bending die, means for detachably mounting the die on the turntable, means adapted to anchor the front end of one of said members in fixed position relative to the die, means for rotating the turntable to wrap said member around the die while the rear end of themember is thereby drawn forward toward the die, a piston adapted to be connected tothe rear end ofthe member, a fluid pressure cylinder housing the piston, and means pivotally mounting the cylinder on said base on an axis parallel to and a fixed distance from the axis of the turntable, said cylinder being adapted to receive fluid pressure in front of the piston whereby to resist forward movement of the piston in the cylinder so as to exert sufilcient tension on the member so thatwhen it is wrapped around the die by rotation of the table against the ten,- sion exerted by the piston and released it will substantially conform to the shape of the die.

15. A combined stretching'and bending machine for bending elongated members into predetermined shapes, comprising a base, a turntable rotatably mounted thereon, a side face bending die, means for detachably mounting the die on the turntable, means adapted to anchor the front end of one of said members for rotation with the turntable, means for rotating the turntable to wrap said member around the die while the rear end of said member is thereby drawn forward toward the die,a piston adapted to be connected to the rear end of said member, a fluid pressure cylinder housing said piston, and means pivotally mounting the cylinder on said base on an axis parallel to and offset from the axis of the turntable, for swinging movement about said pivotal axis through the maximum arc subtended by the path of the die, said cylinder being adapted to receive hydraulic fluid pressure in front of the piston whereby to resist forward movement of the piston in the cylinder sufiiciently to stretch said membernear to its elastic limit.

16. In a contour forming machine, a base, a rotatable table thereon adapted to support, for rotation therewith, a side face die about which a length of metal can be wrapped and a stock anchor for securing a portion of the length of the metal for rotation with the table, a pair of metal stressing fluid pressure operated piston and cylinder assemblages, means respective to the assemblages and connecting them, one to the base and one to the table for rotation with the table, with their axes generally parallel to a plane normal to the table axis, means for supplying fluid pressure to one of said assemblages for urging its piston generally away from the table, means for supplying fluid pressure to the other of said assemblages for urging its piston in a direction generally toward the table, means carried by the :connection to-a length metal ,for :exerting tension thereon upon said rnovement of a'the asso- .oiated piston .generally away from the table, and -a metal engaging :tool carried by the ,piston :of said .other assemblage :for applying pressure "to the length'of'metaLinEa1directionygenerally toward ,thex table.

:17. :In .a contour forming machine, a base, a rotatable table vther,eon,.means totrotate thetable,

.azpairiof metalstressing piston and cylinder assemblages, connecting ;-means respective to and connecting the assemblageson the baseimangu- .larly-spaced relation-,to-each-other about thetable .axis'and with their taxes generally parallel to a planeenormal to the-tableaxis'and connecting one ofthem tothebase forswinging movement about anaxisrgenerallyparallel-to and offset from the piston of the otherzassemblage-being.adapted-for connection to,- a workpiece engaging tool.

18. A combined stretching and bending machine for bending elongated members :into pre determined shapes, ,comprisinga base,.a turntable rotatably mounted thereon and adapted to support, ,for rotation therewith, a bending dieand a stock anchor for anchoring one end of one of said'members for rotation with .the die, means for rotating the-turntable, wherebysaid-members, when so anchored, can beuwrapped .around the die while :the rear :end :of .-said member is there- :by drawn forward'toward-the die, a piston adapted :for connection to a clamp .to be connected to the rear end of said .-.member, a .fluid pressure ,cylin ,der .housingsaid piston .and having its axis generally parallel to the .plane of .the table, :means pivotally mounting the cylinder on a said table -on an axis-parallel to and offset from the axis of the turntable,.saidcylinder being adapted to receive pressure fluid in front of the ,piston whereby to resist forward movement of thepiston in the cylinder sufiiciently to stretch-said membernear to .its elastic limit, pump means for supplying said pressure fluid and-connected in a fluid pressure circuit with the piston, constant pressure control meansin .said circuit and operative :to maintain the pressure of the fluid in-said cylinder substantially constant during movement of the .piston. CYRr'IL J. .BATH.

REFERENCES CITED 'llhe following'references :are of record in-th file :of this :patent:

UNITED STATES PATENTS Number Name Date 397,712 Fowler Feb. 12, 1889 1,690,724 Frederick. Nov. .6, .1928 2,022,915 Jensen Dec. 3, 1935 2,143,443 Kelso Jan. 10,1939 2,190,821 iBroomham .Feb. 20, 1940 .'2,217,053 Henricson Oct. 8, 1940 2,275,619 Enbergetal. -Mar. 10,1942 2,292,731 Amiot. .Aug. 11, 1942 2,327,440 Maize Aug. .24, .1943 2,357,027 Seifried .Aug..29, 1944 2,346,213 Flowers :Apr. 11, 1944 2,411,801 .Nielson Nov. .26, 1946 FOREIGN PATENTS Number Country Date 494,702 Germany 'Mar. 27, 1930

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