US2399745A - Metal drawing apparatus - Google Patents

Description

Search Room May 7, 1946. w. a KERR METAL DRAWING APPARATUS Filed March 27, 1942 5 Sheets-Sheet 2 INVENTOR WALLACE E. KERR W. E. KERR METAL DRAWING APPARATUS Filed March 27, 1942 M ay 7, 1946.

5 Sheets-Sheet 3 INVENTR WALLACE E KERR A ORNEY Search Room '.May 7, 1946. w E KERR 2,399,745

METAL DRAWING APPARATUS Filed March 27, 1942 5 Sheets-Sheet 4 Search Room AMay 7, 1946. w E KERR 2,399,745

METAL DRAWING APPARATUS Filed March 27, 1942 5 Sheets-Sheet 5 /f u ,d lo --M /1 f/so 9 6o so l F15 1B @la L 96 I u I F15 17 WALL'ET'RR Patented May 7, 1946 UNITED STATES Search Room PATENT OFFICE 31 Claims.

This invention relates to metal drawing apparatus and is applicable in the production of drawn tubesfbarsr rodsandrthe, like. As is well understood, apparatus of this naturecomprises, in general, a die or work head, a bench extending outwardly therefrom, and a draw head or carriage movably supported on the bench and adapted to engage the sections being drawn to draw the same through the dies or other working elements incorporated in the work head. The present invention is concerned primarily with the manipulation of the stock engaging grippers mounted on the carriage and with the construction and arrangement of grip bits forming part of the stock gripping members.

The primary object of the invention is the provision of an improved construction for a drawbench carriage of the tong or pliers type in which the friction incident to the opening and closing of the tongs or pliers is materially reduced while nevertheless retaining a general structure of a rugged and durable nature. This object is accomplished by the present invention primarily by employing a unitary frame for the carriage and mounting the tongs on said frame in such manner that the movable portions thereof rest on anti-frictionally mounted rollers. In this manner the advantages of a unit frame or truck is retained while the friction incident to the operation of the tongs is reduced.

Another object of the invention is the provision of an improved clutch for moving the grip bits into pressure contact with the stock to be drawn upon initiation of movement of the carriage away from the work head by the draw chain provided and of an improved arrangement for incorporating the clutch in the drawing apparatus generally. In accordance with usual practice, the clutch includes two parts, one of which is attached to a fixed part of the apparatus as the bench, for example, while the other part is connected with the tongs and mounted on the carriage. In the present invention the fixed part of the clutch is recessed in the bench construction in such manner that it does not interfere with the inspection or maintenance of the dies or working elements of the work head and is protected against damage while the part mounted on the carriage is likewise recessed in a protected out-of-the-way position in the carriage. The parts, however, may be readily adjusted and serviced and the position of the xed part in the bench may be readily varied longitudinally of the bench to insure proper operation of the clutch. Another advantage of the outlined clutch arrangement is that the clutch may be so constructed that during its operation, it has a. tendency to lift the tongs thereby further enhancing the gripping action effected by the same. The 5 arrangement also enables a substantial simplification in the design and construction of the carriage to be effected since it is possible to attach one part of the clutch directly to the movable pin of the tong assembly.

A further object of the invention is the provision in a drawbench carriage of the tong or pliers type of a simple arrangement for closing the tongs manually and for simultaneously closing the tongs and dropping the draw chain engaging hook manually whereby the operation of the apparatus is simplified and its efciency increased. In accordance with the invention, the stated means may comprise a pivotally mounted lever and when the carriage is adjacent the work head, the lever may be employed to assist the clutch in closing the stock grippers, and when the carriage is away from the work head, the means is operative to simultaneously eect the two stated functions while requiring the use of but one hand of the operator, allowing the other hand to be used to guide the end of the stock into the space between the grippers. In this manner substantial time can be saved in reconnecting stock pieces to the carriage from which they may have become accidentally detached.

Yet another object of the invention is the provision of an improved construction for a stock engaging grip carriage of a drawing apparatus in which means separate from the draw chain is provided to move the carriage away from and toward the work head and in which actuation of such means is operative to open and close the stock grippers. Thus by properly manipulating the controls for the carriage moving mechanism, it is possible to control the opening and closing of the grippers even when the carriage is at a distance from the drawing tools and the operator. As will appear hereinafter, this arrangement also insures that the grippers will be opened their full extent as the carriage is returned to the die to engage the next succeeding blank to be drawn. If a cable is employed to return the carriage to the die, the construction of the carriage may be such that tension in the cable may be applied to close the grippers tightly onto the stock,

A still further object of the invention is the provision of an improved construction for an equalizing grip bit of the kind employed for simultaneously drawing two blanks. For this purpose it is usual to employ a rockably mounted grip bit having blank engaging serrations on opposite sides of the pivot point. In accordance with the present invention, this grip bit; is thickened adjacent the pivot point so that the heavy flexural forces encountered therein is successfully opposed while the interval between the axis of movement of thegrip bit and the points of engagement with the stock blanks in a direction spanning the fixed and movable grip bits is kept low so that the force couple tending to roll the movable bit out of its socket is diminished.

The above and other objects and advantages of the invention will become apparent from a consideration of the following detailed specification and the accompanying drawings wherein there is specifically disclosed certain preferred embodiments of the invention.

In the drawings:

Figures 1 and 2 are a plan view and a side elevation, respectively, of a portion of a metal drawing apparatus constructed in accordance with the principles of the present invention;

Figure 3 is an enlarged and detailed partial side elevation of the apparatus of Figures 1 and 2 and Figures 4 and 5 are transverse sections along the lines 4--4 and 5-5, respectively, of Figure 3.

Figures 6 and 7 are, respectively, a partial side elevation and a partial plan of a modified form of draw carriage constructed in accordance with the principles of the invention and Figures 8 and 9 are, respectively, a transverse section and a partial side elevation of the modified carriage of Figures 6 and 7 but showing in operative relation therewith a clutch assembly, one part of which is adjustably secured along the drawbench;

Figures 10 and 11 are, respectively, a front elevation and a plan View of the equalizing grip bit construction of the invention;

Figures 12, 13 and 14 are top, front, and side views, respectively, of a combined manually engageable grip closing and hook releasing mechanism which, as will appear below, may also be used simply as a grip closing device;

Figure 15 is a plan view of a further modied form of a draw carriage constructed in accordance with the principles of the invention, the principal feature of this construction being that the auxiliary carriage moving means may be employed to open and close the grippers; and

Figures 16, 1'7 and 18 are side, front, and rear elevations, respectively, of the apparatus of Figure 15.

Referring first to Figures 1 through 5, reference numeral Il) indicates a holder which is rigidly attached to the end of a bench indicated in its entirety by the reference numeral II and CII which is adapted to slideably receive a die block* I2. Bench II is preferably constructed, as disw`(led in my co-pending application Ser. No. 383,131, led March 13, 1941, and as shown in Figure 4, includes two spaced I beams I3 on the top of which are bolted the angle members I4 which provide supporting tracks and guide surfaces for the draw carriage. On the tracks thus provided the supporting wheels I5 of the carriage run and to move the carriage during drawing operations, a chain I8 is supported on a wear plate I1 positioned intermediate the vertical legs of the angle sections I4. One end of the chain is trained over an idler wheel I8 rotatably mounted between the beams I3 while the outer end thereof passes over a motor driven sprocket as is well understood in the art.

Referring to Figure 1, the principal embodiment of the draw carriage of the invention comprises a rigid unitary frame 20 supported by the wheels I5 as aforesaid and either cast integral with the frame or rigidly secured thereto as by welding, for example, is a heavy block 2I to which is pivotally secured the hook 22. The latter is mounted for movement in a vertical plane and is arranged to fall by gravity into engagement with the moving chain I6 when released in the manner to be described below. Mounted on the carriage 20 are the tongs 23, each carrying a replaceable grip bit 24 at its stock engaging end and these tongs are connected by a vertically extending pivot pin 25. Pivotally connected to the opposite ends of the tongs 23 are the toggle links 26 which, in turn, are pivotally connected to a pin 21 which is mounted in the block 2 I. In operation, the pin 21 is xed with respect to the frame of the carriage while the pin 25 is free to move longitudinally of the carriage and it should be apparent that as the pins 25 and 21 are moved apart, the grip bits 24 will be brought together due to the action of the toggle links 26 and that as the pins are moved together the grip bits will be moved apart.

The tongs 23 together with the pin 25 are of substantial mass and heretofore the friction encountered in the moving of the tongs and pin relative to the frame of the carriage has detracted from the efficient operation of apparatus of the nature involved. In an attempt to overcome this objectionable aspect, it has been proposed to carry the tong pin and therefore the weight of the tongs on one truck while mounting the toggle pin on another truck and by allowing these trucks to move independently of each other the friction encountered in the opening and closing of the tongs is diminished. However, the carriage comprised of these two loosely coupled trucks have, in practice, required much maintenance and is not considered to be entirely satisfactory. In accordance with the present invention, the advantages of the articulated carriage are achieved while the ruggedness and durability of the unitary carriage construction is retained. This is accomplished, in one embodiment of the invention, by rigidly securing a plate 28 to the lower end of the tong pin 25 and Supporting this plate directly on a roller 29 which is anti-frictionally mounted in the frame struts 30 by means of the needle bearings 3I It should be understood that the struts 30 form an integral part of the carriage frame 20. It should also be clear that the weight of the tongs and of the interconnecting pin 25 is carried directly on the anti-frictionally mounted roller 29 and that consequently the tongs may be readily opened and closed with the application of a minimum force in the proper direction.

slideably mounted in abutting relation with the plate 28 is a block 32 to which is pivotally mounted a clutch dog 33. Means, not shown, is provided to limit the downward movementof dog 33 and a spring 34 biases the dog to lowermost position. Dog 33 is arranged to have engagement with a tool steel clutch latch bar 35 which is bolted to a lever 36 pivotally mounted on a support 31. Support 31 is arranged to be clamped to the upper inwardly directed flanges of the I beams I3 by the plate 38 and it should be apparent that by simply loosening the clamp bolts, the position of the support 31 may be readily varied longitudinally of the beams. Lever 36 is biased to upper position in which it is shown in Figure 3 by the spring 39. In operation, as the carriage approaches the die or work head of the apparatus to begin another draw, the dog 33 overrides the latch bar 35 and the parts assume their relatiye positions shown in Figure 3. At the same time, by means to be described below, the hook 22 is allowed to fall onto the chain I6 whereupon the frame 26 and toggle pin 21 begins its outward movement. The tong center pin 25, however, is at rst prevented from moving because of the latch 35 and consequently the tongs will be closed and the grip bits 24 brought into pressure engagement with the end of the blank protruding through the die or to the working element. After completion of this closing movement the force applied to latch bar 35 by dog 33 increases and when this force is suillcient to overcome spring 39, lever 36 rotates and allows dog 33 to escape the latch 35. At this time the draw has commenced and the heavy drawing force acting through the toggle maintains the bits 24 tightly closed until the completion of the drawing operation.

Attached to and extending laterally of the hook 22 is a latch bar 40 which is arranged to be engaged by a dog 4| which is pivotally mounted at its lower end on the struts 30 of the frame 26. To the upper end of the dog 4| is connected a rod 42 slideably mounted in suitable supports as. for example, the projection 43 of the block 2| and a member 44 carried by the tong center pin 25. A spring 45 biases the rod 42 to the left, as viewed in Figures 1 and 2, to normally maintain the latch bar 40 and the hook 22 in raised position in which the hook is free of the chain I6. puring the first part of a draw the hook normally raises of its own accord due to the raised position of the hook pin and when the hook reaches its raised position, it is latched in such position by action of the spring 45. If the hook does not raise of its own accord, a member 46 attached to the hook engages a cam member, not shown, spaced out along the bench and the hook is then raised'a suilicient amount to enable the bar 46 to be latched by the dog 4|. At the completion of the draw the chain drops from the hook and the hook is maintained in a raised position during movement of the carriage back toward the work head. As the latter is approached, the rod 42 engages the latter at 41 to move the rod to the right thereby allowing the hook to drop onto the chain |6. The above mentioned hook raising cam is shown and its operation is explained in my co-pending application Ser. No. 226,477, filed August 24, 1938.

In the modification illustrated in Figures 6 through 9, the frame 50 is generally similar to the frame 26 of the embodiment ilrst described, both frames being an inherent part of a unit truck. The tongs carrying the grip bits 52 are likewise pivotally connected together by a pin 53 and are pivotally connected at their ends opposite the bits to toggle links 54 which are, in turn, pivotally connected to a pin 55 mounted in a block 56 formed integral with or rigidly attached to the frame of the carriage. By referring to Figure 8 it will be observed that the frame 50 is likewise provided with longitudinally extending struts 51 and intermediate the struts 51 and the outer rails of the frame 50 are rotatably mounted rollers 53 on anti-friction bearings carried on shafts spanning the struts and side rails. The rollers 58 are each provided with inner peripheral surfaces of less diameter than the outer peripheral surfaces thereof and supported on the smaller diametered surfaces are the side edges of a plate 53 to which is rigidly connected the tong pin 55. The outer side edge of each of the two Search Room tongs 5I is provided with a short depending iiange which is supported directly on the larger diametered surfaces of the rollers 58. As the center pin l53 is moved relative to the fixed toggle pin 55 the outer side portions of the tongs 5| will have a greater linear motion than the center pin because of the rotation of the tongs about the center pin 55 and this differential movement is compen- Asated for by the diferential construction of the rolls 56. Due to the substantial mass and size of the tongs there is a tendency in the construction of Figures 1 through 5 for the tongs to bind onto the tong center pin and it should be observed that this binding is entirely eliminated in the construction of Figures 6 through 9. Consequently the friction incident to the operation of the tongs is further reduced.

In operation, the carriage 5|! is movably supported on the rails of the drawbench by the wheels 60, four of which are normally provided and a releasable clutch is again employed to withhold movement of the pin 53 to force the tongs into tight engagement with the blank at the start of the outward movement of the carriage by the means described above. This clutch may consist of a tool steel latch bar 6| which is rigidly bolted to the plate 53 and a cooperating tool steel latch'bar 62 which is carried by a pivotally mounted lever 63 which is biased to upper operative position -by the spring 64. Lever 53 is pivotally mounted in a support 65 which, in turn, is securely clamped to the inwardly directed upper flanges of the beams I3 of the drawbench structure. For this purpose a clamp plate 66 and bolts 61 may beemployed and it should be apparent that upon loosening bolts 61 the support 65 may be adjusted longitudinally of the drawbench. With the parts properly adjusted, the interengagement between the bars 6| and 62 prevents movement of the pin 53 at the start of movement of the carrlage 56 and consequently pins 53 and 55 will be moved apart, the toggle closed, and the grip bits 52 brought into tight engagement with the blank to be drawn. When the drawing force reaches a predetermined value. the spring 64 will be overcome, the lever 63 rotated, and the bar 6| will escape the bar 62. Upon return movement of the carriage, bar 6| will override bar 62 and the parts will again assume their relative positions shown in Figure 9. Latch bar 62 is immediately supported in a member 66 having pivotal connection with lever 63 at 63. Member 68 is biased to upper operative position relative to lever 63 by a spring 16, the upper position of member 66 being limited by pin 1|.

In both clutch constructions thus far described, the spring which opposes relative movement of the clutch members to enable the clutching to be effected is much weaker than the spring which opposes the separation of the members in unclutching. Thus the springs 34 and 10 are much weaker in their effect than are the springs 39 and 64. It should also be observed that by reason of the fact that the clutches are positioned below the tongs and operate in vertical planes, the action of the clutches is such that they tend to lift the tongs when they are about to release or are releasing. This action diminishes the effective weight and closing friction of the tongs thereby aiding in the tight closing of the same at a critical time in the drawing cycle.

The arrangement of the parts in the modifica tion of Figures 6 through 9 results in the simpliiication of the design and construction of the apparatus. 'Ihe clutch latch 6| is, in effect, sub

stantially integral with the tong center pin 55 or it may, -if desired, be actually made integral with the pip which feature eliminates certain parts and certain assembly operations.

Figures l and 11 illustrate an equalizinggrip- 5WN bit construction which is operativeatoiirayvmtvlq* blanks simultaneously. The tongs 13 and 14 carry the grip'bits and one of the tongs, as 14, is provided with a cylindrical bore 15 opening along its side wall to the space between the tongs. A grip bit 16 having a part cylindrical rocker projection 11 is mounted on the face of the tong with the projection 11 received in the recess or bore 15. A key 18 prevents the withdrawal of the rocker 11 from its socket 15. Bit 18 is provided vvith serrated blank engaging surfaces evenly spaced above and below the rocker 11 and intermediate these serrated surfaces the bit is thickened at 19. Opposing the bit 16 is a bit88-- dove-tailed in tong "13. Bit 88 is provided with 20 spaced serrated blank engaging surfaces opposite the serrated surfaces of the bit 16 and intermediate the same the bit is recessed at 8| to receive the thickened portion 19 of the bit 16.

Heretofore equalizing grip bits of the fulcrumed type have been made of heavy stock so that the bit would withstand the heavy flexural forces encountered adjacent the fulcrum point. This construction results in a substantial lateral interval between the gripping faces of the bit and the point at which outward movement of the bit is restrained and consequently a large force couple tending to roll the bit out of its holder is created, particularly when short holds are taken on the blanks. 'This condition is avoided by the present invention by so constructing the bits that the center portion of the rockable bit is substantially thickened at its center while its blank engaging faces are kept laterally close to the points of restraint of the bit.

The above mentioned means to manually and simultaneously close the grip bits and release the hook will now be described and this feature is illustrated in Figures 12, 13 and 14 wherein parts identical with the parts included in Figures 1 through 9 bear the same reference numerals as in the gures rst described. Extending upwardly from one side of the carriage frame 50 is a support 83 to which is pivotally mounted a link 84 for rotation about a vertical axis. Pivotally connected with link 84 is a bar 85 which is adapted to engage the side wall of a retaining collar 86 encircling the upper projecting end of the tong pin 53. To the outer end of bar 85 is pivoted at 81 a manually engageable lever 88 which has an enlarged portion provided with a cam surface 89 and slotted to receive the outer part of the bar 85. As viewed in Figure 12, counterclockwise rotation of the lever 88 relative to the bar 85 is lim.. ited by pin 90 and the clockwise rotation of the lever 88 relative to the bar 85 is limited by the stop pin 9|. Secured to the hook release rod 42 is a disk 92 and it should`be apparent that with the parts assembled as shown in the drawing by engaging the outer end f lever 88 and moving the same toward the tong end of the carriage that pressure will be applied to the disk 92 tending to move the rod 42 toward the hook end of the carriage and simultaneously pressure will be applied to the pin 53 tending to move the same away from the pin 55 to close the grip bits in the manner described above.

The above described feature is of particular advantage in the event that the blank being drawn pulls out of the bits while the carriage is moving outwardly along its track and before the completion of the draw since in this case the end of the blank drops and to reconnect the blank with the carriage the operator must rst raise the end of the blank and align the same with the grip bits while the carriage is moved backwardly toward the die or work head. The end must be kept raised while the grip bits are closing and, of course, a closing force must be maintained on the grip bits until the same is taken up by the drawing tension. In operating the present described apparatus, the operator may readily accomplish the lifting of the blank with his left hand, for example, and at the same time he may simultaneously apply closing pressure to the pin 53 and movement to the rod 42 to release the hook. In pulling back on the lever 88, the hook is quickly released and the stop pin 9| moves against bar 85. At this point the bar and lever 88 combine to form, in eect, a lever of the second class and the operator by applying a quick heavy force to the outer end of member 88 can insure the tight closing of the grip bits and maintain the closing pressure until the same is adequately taken up by the drawing tension. The pivotal connection between bar 85 and link 84 enables the members 85 and 88 to be used simply as a second class lever acting on the pin 53 without operating the rod 42. By referring to Figure 13, it will be observed that when the bar 85 and lever 88 are in their lower or at rest positions, the cam 89 is below the disk 92. Thus at the start of the draw the lever 88 may be manually engaged and pulled toward the die block or work head of the machine to assist the clutch above described to close the tongs or grip bits on the blank, if desired. Figures 15, 16, 17, and 18 illustrate a modiied form of draw carriage construction in which the auxiliary carriage moving cable or cables is employed to open and close the tongs or grip bits. As is well understood, it is common practice to employ in addition to the draw chain which applies the heavy drawing force, one or more cables to move the carriage along its support toward or away from the dies when the carriage hook is free of the chain. Control means is provided to govern the movement of the carriage by the auxiliary cable or cables, a complete system being disclosed in my co-pending application Ser. No. 226,477, filed August 24, 1938. In Figures l5 through 18 identical parts bear the same numerals as in the earlier described figures.

Referring to Figure 16, reference numeral 94 indicates a cable length which, when tension is applied thereto, tends to move the carriage 50 back toward the die block or work head of the machine and 95 indicates a cable reach which, when tension is applied thereto, is operative to move the carriage away from the work head. Cables 94 and 95 are connected to a member 96 which is carried by a rod 91 slideably mounted in brackets 98. To the upper portion of pin 53 is connected a longitudinally extending member 99, the outer end of which is slideably received in a guideway |00. Interconnecting members 99 and 98 is the curved plate |8| which is of substantial dimension longitudinally of the carriage and it should be apparent that longitudinal movement of the member 96 results in corresponding longitudinal movement of member 99 and consequently of the ton-g center pin 53.

To the outer end of rod 91 is secured a latch bar |82 and cooperating with the same is a latch carried by plates |01 secured to the hook 22 on opposite sides thereof. Lever` |04 is biased in a clockwise direction, as Viewed in Figure 16, but

when the hook drops, it is moved counterclock- Wise to separate the latch bars |02-|03.

'Ihe operation and advantages of the apparatus described immediately above can be explained as follows: Assume that the recoil at the completion of a draw (which recoil is ordinarily relied on to open the grip bits) is insumcient to open the bits and free the blank, a pull on the cable 95 will shift members 96, |0|, 99 and pin 53 toward the hook end of the carriage and open the tongs in the manner explained above. This relative movement causes latch |03 to fall in back of bar |02, it being assumed that the hook has been raised and latched in the manner explained above, thus locking the tongs in open position. If the return cable reach 94 is now actuated, the carriage will be returned back to the die block and the grip bits 52 will pass over the protruding end of the next blank to be drawn in locked open position. The lock is released when the hook falls by actuation of the rod 42 in the manner described above and if tension is maintained in the cable 94 or if the cable is substantially free from slack at the start of the outward movement of the draw carriage, it will be evident that the members 96, and 99 will be moved in a tong closing direction due to the friction drag of the return cable 94. The acceleration of the carriage maintains tension in the cable 94 until the drawing force is applied through toggles 54.

The above specifically described embodiment of the invention should be considered as illustrative only as obviously many changes may be made therein without departing from the spirit or scope of the invention. For example, while the features of the invention have been specically illustrated as being applied to a draw carriage of the tong type, it should be obvious that substantially all the features are equally applicable, with their attendant advantages, to devices employing other types of gripping mechanisms. Reference sh'ould therefore be had to the appended claims in determining the scope of the invention and all reasonable equivalents should be considered as coming Within the scope of the terms employed therein.

I claim:

A 1. In drawing apparatus having a work head,

' a bench extending outwardly therefrom, a draw carriage movable along said bench, and means to move said carriage in a drawing direction; said carriage comprising a rigid frame mounting a pair of blank engaging grippers movable thereon and relative to each other in engaging a blank and also mounting an element for engaging said means to move, means to move said grippers relative to said frame and to each other upon initiation of movement of the carriage away from said head by said carriage moving means comprising a member fixed in relation to said head and a member connected with said grippers and positioned substantially within said frame, and a releasable connection between said rst and second mentioned members.

2. In drawing apparatus having a work head,

Vfrom said head by said support moving niefns a bench extending outwardly therefrom, a draw carriage movable along said bench, and means to move said carriage in a drawing direction; a pair of blank engaging grippers movably mounted on said carriage, means to move said grippers relative to said carriage and to each other to force the same into pressure engagement with a blank to be drawn upon initiation of movement of the carriage away from said head by said carriage moving means comprising a member connected with said grippers and housed Within said carriage and a second member housed within said bench, and a releasable connection between said first and second mentioned members.

3. In drawing apparatus having a work head, a draw chain having a reach extending outwardly therefrom, and a draw carriage adapted to be moved by said chain; a pair of blank engaging grippers movably mounted on said carriage, means to move said grippers relative to said carriage and to each other to force the same into pressure engagement with a, blank to be drawn upon initiation of movement of the carriage away from said head by said chain comprising a member connected with said grippers, a member xed in relation to said head, a releasable connection between said members, said members being positioned on that side of said carriage which faces said chain reach during the drawing operation.

4. Drawing apparatus comprising in combination a work head, a draw carriage support extending outwardly therefrom, a draw carriage movably mounting a pair of blank engaging grippers movably mounted on said support, a trough extending parallel with said support, a draw chain having a reach received in a portion of said trough; and means to move said grippers relative to said carriage and to each other to close said grippers onto a blank upon initiation of movement of said carriage by said chain comprising a member connected with said grippers, a second member housed within said trough, and a releasable connection between said members.

5.,l?rawing apparatus comprising in combination aiwork'ihea-,hfa draw carriage comprising a movi'sum a pair. of. blank engagingtpngs mounted thereon, means to move said support in a drawing direction; means to move said tongsto closed positions to engageblank'to be drawing,u upon initiation of movement'of said support away comprising a member connected with said tongs, and a member substantially xed in relation to said head, said members adapted to separate when the force therebetween exceeds a predetermined value, said rst mentioned member being operative to apply a lifting force to said tongs during the application of force between said members, said lifting force tending to lift said. tongs in relation to said support.

6. Drawing apparatus comprising in combination a work head, a draw carriage comprising a movable support and a pair of blank engaging tongs mounted thereon, means to move said support in a drawing direction, a pin pivotally interconnecting said tongs; and means to move said tongs to closed positions to engage a blank to be drawn upon initiation of movement of said support away from said head by said support moving means comprising a releasable member rigidly connected with and closely coupled with the lower end of said pin, a member substantially nxed in relation to said head, and a releasable connection between said members.

'7. Drawing apparatus comprising in combination a work head, a draw carriage comprising a movable support and a pair of blank engaging grippers novably mounted thereon, and means to move said support in a drawing direction; means to move said grippers relative to said support and to each other to force the same into pressure engagement with a blank to be drawn upon initiation of movement of the support away from said head by said support moving means comprising a clutch having one part connected with said grippers and another part normally fixed relative to said head, said parts being separable upon the application of a predetermined force therebetween, means applying a minor force opposing interlocking interengagement of said parts, and means applying a major force opposing the separation of said parts.

8. Drawing apparatus comprising in combination a work head, a draw carriage comprising a movable support and a pair of blank engaging grippers movably mounted thereon, and means to move said support in a drawing direction; and means to move said grippers to closed positions to engage a blank to be drawn upon initiation of movement of said support away from said head by said support moving means comprising a member connected with said grippers and a member normally fixed in relation to said head, said members being adapted to separate when the force therebetween exceeds a predetermined value, means applying a major force to one of said members opposing separation between the members, and means applying a minor force to the other of said members opposing the interlocking interengagement of said members.

9. A draw carriage comprising in combination a rigid frame, means movably supporting said frame, a, pair of blank engaging tongs carried by said frame and being pivotally interconnected by a vertically extending pin, and rollers journaled in said frame and positioned on either side of said pin to support the outer portions of said tongs on said frame.

10. Apparatus according to claim 9 further including a roller journaled in said frame and supporting said pin on said frame.

11. A draw carriage comprising in combination a rigid frame, means movably supporting said frame, a pair of blank engaging tongs carried by said frame and pivotally interconnected by a vertically extending pin, means supporting said pin for movement longitudinally of said frame and said tongs for movement longitudinally of said frame as Well as movement about said pin comprising a roller on either side of said pin, a plate supporting said pin, each of said rollers having an inner track and an outer track of larger diameter, the side edges of said plate resting on said inner tracks, and outward side portions of said tongs resting on the outer tracks of the rollers, said rollers being rotatably mounted in said frame.

12. Anegualizing grip bit tor simultaneously i of claim 12 and a cooperating grip bit having a e `-W recessed center portion in its blank engaging face to receive the thickened center portion o1' said first mentioned grip bit.

14. A draw carriage comprising in combination a movable support, a pair of pivotally interconnected blank engaging tongs carried by said support, a draw chain hook pivotally mounted on said support, a latch to retain said hook out of engagement with the draw chain, and manually engageable means operatively connected to said tongs and to said latch and being operative when pressure is applied thereto in a direction toward the blank engaging end of said carriage to release said latch and to move said tongs to closing positions.

l5. A grip bit carriage for a drawing machine comprising a movable support and means connected therewith for attachment to a moving member which is operative to effect the drawing force and movement, grip bits on said carriage and movable relative to said support into open and closed positions, means moveably connected with said support for attachment to an auxiliary moving means which is operative to move said support independently of said moving member, said last mentioned means being operative to move the grip bits relative to said support in a closing direction upon actuation of the auxiliary means for moving the carriage opposite to the direction of movement of said member.

16. Apparatus according to claim 15 further including releasable means to retain the grip bits in open position.

l'l. Apparatus according to claim 15 further characterized in that first mentioned means is movable into and out of engagement with said moving member, releasable means to retain said rst mentioned means out of engagement with said moving member, releasable means to retain the grip bits in open position, and means operable upon release of said first mentioned releasable means to release said second mentioned releasable means.

18. Apparatus according to claim 15 further including releasable means to retain the grip bits in open position, and a manually engageable member operative when actuated to release said releasable means.

19. Drawing apparatus comprising in combination a carriage mounting grip bits which are movable relative thereto into open and closed positions, means to eiect drawing movement of said carriage, a member movably mounted on said carriage and connected with said grip bits and operative when moved relative to said carriage in a direction opposite to the drawing movement of said carriage to move said bits to closed positions, and a carriage return cable attached to said member.

20. Apparatus according to claim 19 further including a releasable means to retain the grip bits in open positions whereby said cable is rendered linoperative to close said grip bits.

' 21. In drawing apparatus having a work head, a carriage supporting a movable blank engaging gripper guided for movement outwardly of said head, and means to move said carriage outwardly of said head in the drawing operation; the combination of means to move said gripper into pressure contact with the blank upon initiation of movement of said carriage by said carriage moving means, said means to move said gripper comprising normally interconnected members adapted to separate when a predetermined force is applied thereto, one of said members being connected to ,said gripper while the other of said members is normally fixed in relation to said head, the point of separation of said members being in substantial longitudinal alignment with the line of force exerted by said carriage moving means.

22. 'In metal drawing apparatus having a work head, a carriage supporting a movable blank engaging gripper guided for movement toward and away from said head, means to move said carriage away from said head, and means to force said gripper into pressure contact with the blank upon initiation of movement of said carriage away from said head, said last mentioned means comprising a yieldable latch normally iixed in relation to said head and a retractible dog on said carriage, said dog being adapted to readily override said latch upon movement of the carriage toward said head but to be restrained by said latch upon opposite movement of said carriage, said latch requiring the application of a substantial force before yielding sufiiciently to allow said dog to override it upon outward movement of said carriage.

23. In metal drawing apparatus having a work head, a carriage supporting a movable blank engaging gripper guided for movement toward and away from said head, means to move said carriage away from said head, and means to force said gripper into pressure contact with the blank upon initiation of movement of said carriage away from said head, said last mentioned means comprising a compound latch normally fixed in relation to said head and a co-operating dog on said carriage, said latch comprising a yieldable member yieldably supporting a second member adapted to be readily depressed by said dog upon movement of said carriage toward said head, said second member being operative to restrain the overriding of said dog when the carriage is moved in the opposite direction, said first mentioned member requiring the application of a substantial force before yielding suiiiciently to allow said dog to override said second member upon outward movement of said carriage.

24. In metal drawing apparatus having a work head and a support extending outwardly therefrom, a carriage supporting a movable gripper for engagement with the stock to be drawn and movable along a path generally parallel with said support, and a clutch operative to close said gripper onto a piece of stock upon initiation of movement of said carriage by the drawing force applying means, the combination of releasable means mounting an operative element of said clutch at a selected position on said support whereby said clutch may be made to function at a selected distance from said work head.

25. In a draw carriage having a gripper adapted to be moved into pressure engagement with a work piece to be drawn the combination of means to move said gripper into pressure engagement with said work piece, and a second means to move said gripper into pressure engagement with said work piece comprising a manually engageable lever adapted to eect such movement upon the application of force thereto in a direction toward the work piece engaging end of said carriage, the interconnection between the parts being such that operation of said rst means does not result in movement of said lever.

26. In a draw carriage having a pair of tongs and a laterally movable pin interconnecting said EBCH 00m tongs whereby movement of the pin eiects open and closing movement of the tongs as well as a chain hook and a latch to retain said chain hook in elevated position, the combination of a compound lever having pivotally interconnected portions and means to limit the relative movement of the portions pivotally mounted for rotation about normal axes, said lever being operative when positioned in one plane of movement to simultaneously release said latch and move said pin in a tong closing action and being operative when in another plane of movement to actuate only said pin in a tong closing direction.

27. In drawing apparatus having a work head,` a draw carriage, means si igpedputwardwlugw said work headlomoyemsaid carriage in andimtw'fi said work head and said moving means opposing the tensile stress existent between said carriage and work head during a draw, a pair of blank engaging grippers movably mounted on said carriage, means to movmsaidxrippersrelae tive to said carriage andYto-eaclirnther.toiorceM the same into pressureengagemennwith theblankm to be drawn uponl initiatiogMQl, movementoffthem carriage awayfrfigi feaidlwprknead by said mov. ing mean's`coinpr'ising a member connected with said grippers and a member substantially housed within said structural unit, and a releasable connection between said first and second members.

28. In a drawbench having a work head and a draw carriage moving means, a draw carriage comprising in combination a rigid frame, means to movably support said frame, an element on said frame for engaging said moving means, a pair of blank engaging tongs, a pivot pin pivotally interconnecting said tongs, a member supporting said tongs and pin, and a roller movably supporting said member on said frame.

29. In a drawbench having a work head and a draw carriage moving means, a draw carriage comprising in combination a rigid frame, means movably supporting said frame, an element on said frame for engaging said moving means, a pair of blank engaging tongs carried by said frame, means comprising a member movable relative to said frame to support at least a portion of the Weight of said tongs on said frame and being operative to move said tongs relative to each other to close the same, and a roller supporting said member on said frame.

30. In apparatus for drawing elongated metal blanks and having a work head, a bench extending outwardly therefrom, a draw carriage movable along said bench, and means to move said carriage in a drawing direction; a pair of blank engaging grippers movably mounted on said carriage, means to move said grippers relative to said carriage and to each other to force the same into pressure engagement with a blank to be drawn upon initiation of movement of the carriage away from said work head by said carriage moving means comprising a member connected with said grippers and a second member connected with said bench, said second member being always positioned outwardly of said work head in space otherwise unavailable for manipulation of the elongated blank, and a releasable connection between said first and second mentioned members.

31. A draw carriage for a drawbench having plied to said stock length with progressively in creasing clamping pressure, and rotatable means supporting said grippers on said frame whereby substantially al1 the friction resulting wholly from the weight of said pair of grippers incident to the closing movement of said pair of grippers is substantially diminished.

WALLACE E. KEER.

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