US3216234A - Drawbench - Google Patents

Description

Nov. 9, 1965 G. A. MITCHELL DRAWBENCH 5 Sheets-Sheet 1 Filed May 17; 1963 INVENTOR George A. Mitchell 71/227 ATTORNEY Nov. 9, 1965 s. A. MITCHELL.

DRAWBENCH Filed May 17, 1963 5 Sheets-Sheet 3 INVENTOR.

GEORGE A.MITCHELL Maw Nov. 9, 1965 cs. A. MITCHELL DRAWBENCH 5 Sheets-Sheet 4 Filed May 17, 1963 INVENTOR. Q.7M|TCHELL A'I'Tm Nov. 9, 1965 s. A. MITCHELL DRAWBENCH 5 Sheets-Sheet 5 Filed May 17, 1963 INVENTOR GEORGE AMITCHELL AT;:; N

United States Patent 3,216,234 DRAWBENCH George A. Mitchell, Youngstown, Ohio, assignor to Lombard Corporation, Youngstown, Ohio, a corporation of Ohio Filed May 17, 1963, Ser. No. 281,225 4 Claims. (Cl. 72-288) This application is a continuation-in-part of copending application Serial No. 861,388, filed December 22, 1959, now abandoned.

This invention relates to drawbenches of the types having a draw carriage adapted to pull workpieces, such as tubes, through a die. More particularly, the invention relates to a drawbench wherein the prime mover for the draw carriage is a fluid motor.

As is known, a drawbench employs, as a basic component, a circular die through which a workpiece is drawn in order to elongate it and reduce its diameter while imparting cold-working properties to the material. In the drawing operation, a reduced diameter end of the workpiece is inserted through the die, and this end is engaged by gripper jaws carried on a draw carriage or dolly which travels on a track extending parallel to the central axis of the die. When the carriage is forced away from the die, the workpiece is drawn therethrough. In the case where the workpiece is a tube, it is first loaded onto a mandrel located on the side of the die opposite the track, and this mandrel forwards a reduced diameter end of the tube through the die where it is engaged by the aforesaid gripper jaws on the draw carriage. As the draw carriage moves away from the die, the tube is pulled through the annular opening defined between the periphery of the die and the periphery of the mandrel.

In the past, it has been common to pull the draw carriage away from the die during a drawing operation by the use of chains. In one type of common chain drawbench, the draw carriage is connected to the draw chain or chains by hook devices which automatically retract when the carriage is not under tension. This arrangement is disadvantageous in the case of costly alloys where it is desired to stop the drawing operation before its completion to examine the progress of the drawn workpiece; and even if the draw carriage is permanently connected to the chain, expensive electrical controls are required for stopping and starting the drive motor for the chains. Another disadvantage of chain drawbenches is the pulsating pull normally associated with the chain drive due to the articulation of the chain passing over the drive sprockets. Such pulsations occur due to variations in the pitch diameter of the sprocket and produce undesirable effects on certain types of materials drawn on the bench. As the capacity of the bench increases, thus requiring a larger chain, this effect is accentuated.

Still another disadvantage of chain-type benches resides in their inability to readily vary the speed of the draw carriage during a drawing operation. That is, the chain is driven by electric motors which require extremely complicated and expensive control systems to vary the speed of the motor. For that matter, many chain-type benches employ a drive motor which operates continually at a constant speed with the draw carriage being connected to the chains by detachable hook devices.

Many of the disadvantages of chain-type benches can be overcome by using a hydraulic cylinder as the prime mover. This facilitates an infinitely variable draw speed by the use of a variable volume pump driven by a constant speed motor. In addition, the pulsating pull of chain benches is eliminated and replaced by a smooth drawing force which can easily be accelerated, decelerated or stopped during the drawing operation.

Patented Nov. 9, 1965 ice Hydraulic drawbenches, as such, are not new; however most benches of this type employ a cylinder aligned with the die axis at the end of the draw carriage track opposite the die, the arrangement being such that the piston within the cylinder pulls the draw carriage away from the die. This, however, means that the length of the cylinder must be approximately equal to that of the track, with the result that the overall length of the bench is greatly increased. The maximum draw length established for such benches is about 45 feet, far below the maximum for chain-type benches due to various problems encountered, not the least of which is supporting the piston rod when it is extended out of the cylinder.

The primary object of this invention is to provide a new and improved hydraulic drawbench arrangement which overcomes the aforementioned disadvantages of conventional chain and hydraulic drawbenches.

Another object of the invention is to provide a hydraulic drawbench wherein the hydraulic cylinder employed does not increase the overall length of the bench.

A further object of the invention is to provide a hydraulic drawbench arrangement wherein the length of the hydraulic cylinder for a given drawing length can be decreased, thereby minimizing or eliminating problems encountered in supporting the piston rod of an extremely long cylinder when it is extended out of the cylinder.

In accordance with the invention, a drawbench is provided wherein the hydraulic cylinder for actuating the draw carriage, instead of being at the end of the track opposite the die, is located beneath the existing drawbench structure such that it does not increase the overall length of the bench. In one embodiment of the invention, the hydraulic cylinder employs a ram-type piston which is connected at its forward end to the draw carriage, the arrangement whereby the stroke of the cylinder is effecout of the cylinder, it will cause the draw carriage to move away from the die. In another embodiment of the invention, the piston of the hydraulic cylinder located beneath the existing drawbench structure is connected to the draw carriage through a distance multiplying cable arrangement whereby the stroke of the cylinder is effectively doubled. This means that the cylinder need be .only one half the length of the draw carriage and, like were limited to a draw length of about 45 feet.

The above and other objects and features of the inverltion will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIGURE 1 is a top view of one embodiment of the invention;

FIG. 2 is a side view of the drawbench shown in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1 showing a supporting frame section for the track structure of the drawbench shown in FIGS. 1 and 2;

FIG. 4 is an illustration of the hydraulic actuating cylinder for the drawbench of FIG. 1 and 2, showing its length in comparison with its diameter;

FIG. 5 is a cross-sectional view showing the construction of the hydraulic cylinder of FIG. 4;

FIG. 6 is a schematic illustration of the operation of another embodiment of the invention wherein the hydraulic actuating cylinder is connected to the draw carriage of the drawbench through a distance multiplying cable arrangement;

FIG. 7 is a side schematic view of the drive system shown in FIG. 6;

FIG. 8 is a top view of the drive system shown in FIGS. 6 and 7;

FIG. 9 is a side elevational view of the embodiment of the invention schematically illustrated in FIGS. 6, 7 and 8;

FIG. 10 is a cross-sectional view taken substantially along line XX of FIG. 9 showing the arrangement of the sheave carriage and draw carriage; and

FIG. 11 is a schematic illustration of a further embodiment of a distance multiplying arrangement.

Referring to FIG. 1, the numeral 10 designates a die stand having a die 12 therein. The die stand 10 is supported on a track assembly, generally indicated at 14, which extends parallel to the central axis of the die on one side thereof. The track structure is comprised of a plurality of spaced frame sections 16, an example of which is shown in FIG. 3. Each frame section comprises a pair of supporting members 18 and 20 which extend upwardly from a base 22. The members 18 and 20 are inter-connected by means of a steel plate 24 having an arcuate opening 26 provide-d in its central portion. Secured to the periphery of the arcuate opening 26 is a bronze liner or wear strip 28. The wear strips in the openings 26 of the several frame sections serve to guide and support the piston of an actuating hydraulic cylinder, hereinafter described, when it extends along the track structure 14.

Supported on the members 18 and 20 are a pair of tracks or guideways 30 and 32 which serve to guide a draw carriage 34 (FIGS. 1 and 2) along a path of travel which is in general alignment with the axis of die 12. The draw carriage 34 is provided with a pair of gripper jaws 36 which serve to engage the forward end of a tube inserted into the die 12. After the jaws 36 engage the end of a tube, the carriage 34 will be moved to the left as shown in FIGS. 1 and 2 to thereby pull the tube through the die in a manner hereinafter described.

To the right of die stand 10, as shown in FIGS. 1 and 2, is a mandrel supporting table or structure 38 which comprises an I-beam 40 or the like structure on a 'plurality of spaced structures 42, substantially as shown. Above the I-beam 40 is a trough 44 which supports the mandrel 46 and a tube carried thereby during a drawing operation. The right end of struc-- ture 38, as shown in FIGS. 1 and 2, is provided with v a mandrel manipulating mechanism which comprises a short stroke hydraulic cylinder 48 having its piston rod connected to a reciprocable actuating block 50. As shown, the block 50 is provided with a pair of guiding rods 52 and 54 slideable within bearings 56 which are welded or otherwise securely fastened to opposite sides of the I-beam 40. The mandrel 46 is pivotally connected to the upper portion of block 50 whereby the mandrel and the tube carried thereby may be moved to the left or right by actuating the cylinder 48. In operation, the cylinder 48 will be initially pressurized to force the block 50 and mandrel 46 to the right as shown in FIGS. 1 and 2. Thereafter, the forward end of the mandrel 46 is elevated to the position shown in FIG. 2 where a tube from a tube storage rack, not shown, may be threaded onto the mandrel. The forward end of the tube is swaged or reduced in diameter such that when the mandrel is lowered into a horizontal position, the cylinder 48 may be actuated to move the block 50 and the tube-carrying mandrel to the left. In this process the swaged or reduced diameter end of the tube is passed through the aperture formed by the die where it may be engaged by the gripper jaws 36 carried on draw carriage 34. The draw carriage is then forced to the left as shown in FIGS. 1 and 2 to thereby pull the tube blank through the die. The blank is thereby reduced tothe dimensions of the annular open ing between the periphery of the die and the periphery of the enlarged head 47 of the mandrel which extends into the die. Although a single mandrel and a single die have been shown herein for purposes of simplicity, it should be understood that a plurality of mandrels and dies may be used if desired without departing from the scope of the invention. Actually, most drawbenches will incorporate a plurality of dies and mandrels rather than the single die arrangement illustrated in the drawmgs.

In order to force the draw carriage 34 to the left as shown in FIGS. 1 and 2, there is provided a fluid motor (FIGS. 4 and 5) which comprises a hydraulic cylinder 58 having a ram-type piston 60 reciprocable therein. The cylinder 58 is carried by the mandrel supporting structure 38 and has a length at least equal to the maximum expected length of a tube which is to be drawn. In most cases this length will be approximately equal to that of the track structure 14 which, incidentally, is longer than the mandrel supporting structure 38. As the piston 60 moves forwardly out of the cylinder 58, it will pass through successive ones of the bushings 28 in the frame sections 16. Thus, the frame sections support the piston against gravity during a drawing operation. Otherwise, the weight of the piston might cause it to bow downwardly while it is in its fully extended position where the draw carriage 34 has moved to the left end of track structure 14. The fluid motor comprised of cylinder 58 and piston 60 is single acting, meaning that the piston 60 will move in a power stroke to the left only as shown in FIGS. 1 and 2. Movement of the piston to the left is accomplished by opening surge valve 62 at the right end of cylinder 58 which then connects the cylinder to a source of high fluid pressure, not shown. At the completion of a drawing operation, the surge, valve 62 is connected to a low pressure reservoir and means, not shown, such as a continuous chain, return the draw carriage 34 to its initial starting position where the cycle is repeated.

With the arrangement shown in FIGS. 1-3, extremely high drawing forces, on the order of one million pounds or over, can be achieved. Furthermore, the speed of the draw carriage 34 can be made infinitely variable by merely regulating the variable volume pumps, not shown, which supply fluid under pressure to the cylinder. Thus, the apparatus can easily accommodate tubes of various materials which require dilferent drawing speed. The drawing operation may be stopped and again started by merely shutting valve 62 after drawing has initially started. All of the foregoing advantages are, of course, unobtainable in conventional chain-type benches as was explained above.

In FIG. 4 the length of cylinder 58 as compared with its diameter is shown where the length of the cylinder is many times its diameter. The cylinder is formed from three sections A, B and C which comprise sections of pipe having flanged ends bolted together as at 64 and 66. In FIG. 5 it can be seen that the left end of the cylinder 58 is provided with a sealing head which comprises a generally annular member 68 connected by means of bolts 70 to a flange 72 on section A of the cylinder. The annular member 68 is provided with a circular recess 74 which carries a packing ring 76 and annular bushing 78 of bronze or some other similar metal. .The end of annular member 68 is provided with an end plate 80 which is connected to the annular member 68 by means of bolts 82. A small wiping seal 84 is provided in a recess 85 formed in the end plate 80, substantially as shown.

The ends of sections A and B which are bolted together at 64 are bored as at 86 and 88 to provide a recess in the inner periphery of the cylinder 58. Received within this recess is an annular bronze bushing 90, it being understood that a similar bronze bushing is provided at junction 66 between sections B and C. Between bushings 90 and annular member 68 is a second bronze bushing 92 which is slideably positioned within the cylinder. This latter bushing does not fit within a recess and has an outer circumference substantially coincident with the inner circumference of the cylinder 58. One or more of the bushings 92 may be provided between annular member 68 and bushing 90, or between junctions 64 and 66. To restrain the bushing 92 against axial movement, a pair of cylindrical spacers 94 and 96 are provided. These spacers are loosely fitted within the cylinder to permit thermal expansion of the various parts.

The inner diameters of bushings 78, 90 and 92 are all equal. These bushings receive the piston 60 which is a tubular member having circular plugs 98 provided at its opposite ends. When the right end of cylinder 58 is pressurized, the piston 60 will be forced to the left as shown in FIG. 2. In so doing, it rides on the inner peripheries of the bushings 78, 90, 92, etc. Thus, this piston 60 will make contact with the sides of the cylinder at spaced points only, these points being at the bushings 78, 90, 92, etc. As will be understood, only the various bushings 78, 90, 92, etc. need be machined since they are the only members which make contact with the sliding piston 60. Generally speaking, the arrangement shown above is practical whenever the length of the cylinder is at least thirty times its diameter and can be extended to almost any length within reason.

With reference now to FIGS. 610, another embodiment of the invention is shown which again includes a die stand 100 as well as a draw carriage 102 which moves on tracks or guideways toward and away from the die stand 100. When the draw carriage 102 is forced away from the die stand 100, it pulls tubes 104 through dies in the stand 100.

In this case, however, the hydraulic actuating cylinder 106 is connected to the draw carriage through a distance multiplying cable arrangement. In this respect, it will be noted that the piston rod 108 of cylinder 106 is connected to a sheave carriage 110 which travels on an I- beam track 112 located beneaththe tracks for the draw carriage 102 .at-the base of the drawbench. Carriedon the sheave carriage 110, as best shown in FIG. 10, are sets of sheaves 114, 116 and 118, 120. As will be understood, the carriage 110 and the sheaves carried thereby will reciprocate back and forth along the track 112 when the cylinder 106 is pressurized to move the piston rod 108 in one direction or the other.

Each of the sheaves 114420 is freely rotatable about a common axis extending perpendicular to the longitudinal axes of the dies in die blocks 100. The sheave carriage 110 is connected to the draw carriage 102 through a pair of cables. The one cable, for example, has one end connected to the drawcarriage at 122. From this point, the cable extends through an upper reach 124 and around a sheave 126 adjacent the die block 100 to a lower reach 128. From the lower reach 128 the cable pass-es around the inside sheave 118 and thence to a take-up assembly 130. From the take-up assembly 130, the cable passes around the sheave 116 on carriage 110: is provided with a lower reach 132 which passes around a sheave 134 adjacent the die stand 100; and finally is provided with an upper reach 136 connected to the draw carriage 102 at point 140.

In a somewhat similar manner, a second cable is connected to the opposite end of the draw carriage 102 as at 142 and 144. From point 142, the second cable extends through an upper reach 146, around a sheave 148 at the trailing end of the drawbench (see FIGS. 7 and 8); and through a lower reach 150 and around the sheave 120 on carriage 110. From the sheave 120 the second cable passes around a second take-up assembly 152 and thence around the sheave 114 on carriage 110. From the sheave 114 the cable passes through a lower reach 154; around a second sheave 156 at the trailing end of 6 the drawbench and through an upper reach 158 to the point 144.

With the arrangement shown in FIG. 6, movement of the piston rod 108 and the sheave carriage carried thereby to the right will cause the draw carriage 102 to move to the left and away from the die stand 100. That is, as the carriage 110 moves to the right, the outside sheaves 114 and will rotate in a counterclockwise direction while the lower reaches and 154 are increased in length with the upper reaches 146 and 158 being decreased in length. This pulls the draw carriage 102 away from the die stand 100, thereby increasing the length of the upper reaches 124 and 136 while decreasing the length of the lower reaches 128 and 132 with the inner sheaves 116 and 118 rotating in counterclockwise directions also.

If the piston 108 and the carriage 110 move fro-m right to left as viewed in FIGS. 6 and 7, the above process is reversed with the sheaves 114120 rotating in clockwise directions, the reaches 124 and 126 being shortened, and the reaches 146 and 158 being increased in length. Tension in the cables is controlled by means of the take-up assemblies 130 and 152. That is, the take-up assembly 130 can be drawn toward the die stand 100 by means of a screw take-up mechanism 160; and, similarly, the takeup assembly 152 can be moved toward the sheaves 148 and 156 by means of a screw mechanism 162.

In place 'of the take-up assemblies 130 and 152, the cables on either side of the draw carriage 102 could be in two parts with the end of each part being anchored in close proximity to the positions of the assemblies 130 and 152. These assemblies, however, provide a convenient means for maintaining tension in the cables and, of course, necessitate only two cable lengths rather than four if each cable is in two parts.

With the arrangement shown, one foot of travel of the sheave carriage 110, for example, will cause the draw carriage 102 to move two feet, thereby achieving a two to one distance multiplication. That is, as the sheave carriage 110 moves to the right through a distance of one foot, the lengths of the cable above and below the sheave must each increase by one foot, with the result that the lengths of reaches 146 and 158 are decreased in length by two feet. Thus, the length of cylinder 106 need be only about one half the length of the draw carriage track instead of the full length as in the embodiment of FIGS. 1 and 2. Furthermore, the arrangement of FIGS. 6-10 enables the power stroke of the cylinder 106 to be a pulling action rather than a pushing action as in FIGS. 1 and 2. That is, since the directions of movement of the draw carriage 102 and the sheave carriage 110 are always reversed, the draw carriage 102 will move away from the die stand 100 during a draw ing operation while the piston rod 108 moves from left to right under tension. This eliminates the need for the ram-type piston 60 shown in FIGS. 1 and 2 and the attendant problems involved in maintaining tolerances between the piston and cylinder.

In order to return the draw carriage 102 tothe die stand 100 at the completion of a drawing operation, the piston rod 108 is pushed out of the cylinder 106 and is under compression; however at this time very little force is required to return the draw carriage 102 with the result that there will be very little tendency for the piston rod to buckle.

With reference, now, to FIGS. 9 and 10, the reference numeral represents generally the main framework of the drawbench assembly schematically illustrated in FIGS. 68 and is comprised of a plurality of spaced frame sections 172, as best shown in FIG. 10. The frame sections 172 may be fabricated of ordinary structural members welded or otherwise securely fastened together. Each section includes an upright member 174 and a horizontally disposed cantilever beam 176 extending outwardly from the upright member or post 174. Depending downwardly from the outer end of the cantilever beam 176 is a short beam section 178, which carries at its lower end a track support 180. The support 180 is one of a complementary pair, a second support 182 being carried by the post 174, as shown.

As will be understood, the complete drawbench assembly incorporates a plurality of frame sections 172, mounted in spaced relation along the length of the drawbench. Carried by the supports 180 and 182 of such sections are spaced tracks 184 and 186. The tracks 184 and 186 support the draw carriage 102 against gravity and guide it throughout the length of the drawbench. On either side of the draw carriage 102 is a second pair of tracks 188 and 190 in abutment with rollers 192 and 194 carried on the draw carriage 102. The rollers 192 and 194 are forced outwardly into engagement with the tracks 188 and 190 by shock absorbers as is more fully explained in US. Patent No. 2,861,679. Above the cantilever beam 176 is a tube storage rack 196, and beneath the rack 196 is a platform 198 onto which tubes from the storage rack 196 are placed preparatory to their being loaded onto mandrels in a manner hereinafter described.

Projecting outwardly from the bottom of the supporting post 174 is a member 200 which supports the I-beam track 112. Reciprocable along the I-beam track 112 by means of guide rollers 202 is the sheave carriage 110 which carries sheaves 114-120. Above the member 200 and the sheave carriage 110 is an inclined table 204 onto which tubes drop after being released from the gnipper jaws 206 of the draw carriage 102. When the tubes drop onto the inclined table 204 they will roll into a storage bin 206 where they may be picked up by a crane or other suitable device.

With specific reference, now, to FIG. 9, it will be noted that to the right of the main drawbench frame 170 and the die block 100 is a mandrel table 208 which carries a plurality of mandrels 210. The mandrels 210 are pivotally anchored at the right end of the mandrel table 208 as at 212 and are adapted to be elevated into the position shown by means of a hydraulic or pneumatic cylinder 214. In the drawing operation, tubes to be drawn on the platform 198 (FIG. 10) are loaded onto the mandrels 210 and the cylinder 214 actuated to lower the loaded mandrels such that they are axially aligned with the dies in the die block 100. Thereafter, the mandrels 210 are pushed forwardly by means in the mandrel anchoring mechanism 212, not shown, whereby swaged or reduced diameter ends of the tubes on the mandrels 210 are forced through the dies. These reduced diameter ends are then engaged by the gripper jaws 206 (FIG. '10) on the draw carriage 102. Thereafter, the cylinder 106 is pressurized to pull the sheave carriage 110 to the right as viewed in FIG. 9, thereby forcing the draw carriage 102 away from the die stand. In this process, the tubes are drawn through the dies and are reduced in diameter. At the end of the drawing operation when the trailing ends of tubes pass through the dies, they will jump forwardly with considerable force, the obvious reason being that the tubes are under tension during the drawing operation and the sudden release of such tension is accompanied by the release of energy which propels the tubes forwardly. In order to cushion the impact of the tubes, shock absorbing devices are provided in the draw carriage 102, a suitable shock absorbing arrangement being shown in the aforesaid US. Patent No. 2,861,679.

Control of the cylinder 106 and, hence, the draw carriage 102 is by means of limit switches spaced along the length of the guideway 112 above the sheave carriage 110. The control system may be of the type shown in copending application Serial No. 101,715. In essence, the opposite ends of the cylinders 106 are connected to the output ports of a reversible, variable displacement pump which may selectively apply fluid under pressure to either end of the cylinder, and which may be operated to gradually increase its output pressure in either direction from zero up to a maximum limit. Thus, the drawing operation may be started gradually rather than abruptly as in the case of a mechanical bench, and the draw carriage may be easily stopped at any point along the draw by reducing the pump output pressure to zero.

With reference now to FIG. 1, still another embodiment of the invention is shown which is identical in operation to the embodiments of FIGS. 6-10, except that a further distance multiplication is achieved. In this case, the lower I-beam guideway 112 is replaced by a stationary rack 212, while above the stationary rack 212 is a rack 214 which can move forwardly or backwardly along the drawbench frame on guideways, not shown. The sheave carriage and the sheaves carried thereby are supported on the rack 214 and reciprocate therewith. Between the gear racks 212 and 214 is a gear 216 which meshes with both of the gear racks. The gear 216 is connected as shown, to the piston rod 108 of the cylinder 106. From a consideration of the arrangement shown in FIG. 11, it will be readily appreciated that when the piston rod 108 moves to the right through a distance of one foot, for example, the upper movable gear rack 214 will move to the right through two feet. The sheave carriage 110 will also move through two feet; while the draw carriage 102 will move through four feet in accordance with the explanation given above. Thus, in the arrangement shown in FIG. 11 a four to one distance multiplication is achieved in contrast to that of FIGS. 6-10.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a drawbench including a drawing die, a track structure extending parallel to the axis of said die on one side thereof, and a draw carriage movable along said track structure for pulling workpieces through said die; the improvement which comprises a hydraulic cylinder assembly including piston and cylinder elements extending parallel to the axis of said die, one of said elements being fixed in position and the other element being movable relative thereto, said fixed element extending at least partially on the side of the die opposite the track structure, a single sheave carriage operatively connected to said movable element and mounted for reciprocating movement relative to said track structure, pairs of coaxial sheave devices rotatably carried on opposite sides of said sheave carriage, pairs of sheave devices at opposite ends of said track structure, first cable means having its opposite ends connected to one end of the draw carriage, said first cable means passing around one sheave of each pair of sheaves on opposite sides of said sheave carriage as well as around the pair of sheave devices at one end of the track structure and around a stationary sheave at said one end of the track structure, second cable means having its opposite ends connected to the other end of the draw carriage, said second cable means passing around one sheave of each pair of sheaves on opposite sides of the sheave carriage, said second cable means also passing around the pair of sheaves at the other end of the track structure as well as a stationary sheave at said other end of the track structure, the arrangement being such that movement of the sheave carriage in one direction will cause said draw carriage to move in the opposite direction.

2. In a drawbench including a drawing die, a track structure extending parallel to the axis of said die on one side thereof, and a draw carriage movable along said track structure for pulling workpieces through said die; the improvement which comprises a hydraulic cylinder assembly including piston and cylinder elements extending parallel to the axis of said die, one of said elements being fixed in position and the other element being movable relative thereto, sheave carriage means operatively connected to said movable element and mounted for reciprocating movement relative to said track structure, a first pair of sheave devices rotatably carried on said sheave carriage, a second pair of sheave devices at an end of said track structure, a cable tensioning and take-up assembly positioned at said end of the track structure and inwardly of the second pair of sheave devices, cable means connected to one end of the draw carriage, said cable means having an end connected to said one end of the draw carriage and extending around a sheave device in said second pair, thence around a sheave device in said first pair, thence to said take-up assembly and around the other sheave device in said first pair, and finally around the other sheave device in said second pair back to said one end of the draw carriage where it is connected thereto, and means for selectively drawing said tensioning and take-up assembly toward said second pair of sheave devices to thereby tighten the cable means.

3. The improvement of claim 2 wherein said cable means comprises a continuous length of cable having its opposite ends connected to said end of the draw carriage, and wherein said tensioning and take-up device includes a sheave around which the continuous length of cable passes.

4. In a drawbench including a drawing die, a track structure extending parallel to the axis of said die on one side thereof, and a draw carriage movable along said track structure for pulling workpieces through said die; the improvement which comprises a hydraulic cylinder assembly including piston and cylinder elements extending parallel to the axis of said die, one of said elements being fixed in position and the other element being movable relative thereto, sheave carriage means operatively connected to said movable element and mounted for reciprocating movement relative to said track structure, a first pair of sheave devices rotatably carried on said sheave carriage, a second pair of sheave devices rotatably carried on said sheave carriage, a third pair of sheave devices at one end of said track structure, a fourth pair of sheave devices at the other end of said track structure, a first cable tensioning and take-up assembly positioned at said one end of the track structure and inwardly of the third pair of sheave devices, a second cable tensioning and take-up assembly positioned at said other end of the track structure and inwardly of the fourth pair of sheave devices, first cable means connected to said one end of the draw carriage, said first cable means having an end connected to said one end of the draw carriage and extending around a sheave device in said third pair, thence around a sheave device in said first pair, thence to said first take-up assembly and around a sheave device in said first pair, and finally around a sheave device in said third pair back to said one end of the draw carriage where it is connected thereto, second cable means connected to the other end of the draw carriage, said second cable means having an end connected to said other end of a draw carriage and extending around a sheave device in said fourth pair, then around a sheave device in said second pair, thence to said second take-up assembly and around a sheave device in said second pair, and finally around a sheave device in said fourth pair back to said other end of the draw carriage where it is connected thereto, and means for selectively drawing said first and second tensioning and take-up assemblies toward said third and fourth pairs of sheave devices repectively to thereby tighten the first and second cable means.

References Cited by the Examiner UNITED STATES PATENTS 234,211 11/80 Stewart 205-5 897,922 8/08 Noyes et al. 2055 1,870,419 8/32 Palmer 205-7 FOREIGN PATENTS 782,636 9/57 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

Claims (1)

1. IN A DRAWBENCH INCLUDING A DRAWING DIE, A TRACK STRUCTURE EXTENDING PARALLEL TO THE AXIS OF SAID DIE ON ONE SIDE THEREOF, AND A DRAW CARRIAGE MOVABLE ALONG SAID TRACK STRUCTURE FOR PULLING WORKPIECES THROUGH SAID DIE; THE IMPROVEMENT WHICH COMPRISES A HYDRAULIC CYLINDER ASSEMBLY INCLUDING PISTON AND CYLINDER ELEMENTS EXTENDING PARALLEL TO THE AXIS OF SAID DIE, ONE OF SAID ELEMENTS BEING FIXED IN POSITION AND THE OTHER ELEMENT BEING MOVABLE RELATIVE THERETO, SAID FIXED ELEMENT EXTENDING AT LEAST PARTIALLY ON THE SIDE OF THE DIE OPPOSITE THE TRACK STRUCTURE, A SINGLE SHEAVE CARRIAGE OPERATIVELY CONNECTED TO SAID MOVABLE ELEMENT AND MOUNTED FOR RECIPROCATING MOVEMENT RELATIVE TO SAID TRACK STRUCTURE, PAIRS OF COAXIAL SHEAVE DEVICES ROTATABLY CARRIED ON OPPOSITE SIDES OF SAID SHEAVE CARRIAGE, PAIRS OF SHEAVE DEVICES AT OPPOSITE ENDS OF SAID TRACK STRUCTURE, FIRST CABLE MEANS HAVING ITS OPPOSITE ENDS CONNECTED TO ONE END OF THE DRAW CARRIAGE, SAID FIRST CABLE MEANS PASSING AROUND ONE SHEAVE OF EACH PAIR OF SHEAVES ON OPPOSITE SIDES OF SAID SHEAVE CARRIAGE AS WELL AS AROUND THE PAIR OF SHEAVE DEVICES AT ONE END OF THE TRACK STRUCTURE AND AROUND A STATIONARY SHEAVE AT SAID ONE END OF THE TRACK STRUCTURE, SECOND CABLE MEANS HAVING ITS OPPOSITE ENDS CONNECTED TO THE OTHER END OF THE DRAW CARRIAGE, SAID SECOND CABLE MEANS PASSING AROUND ONE SHEAVE OF EACH PAIR OF SHEAVES ON OPPOSITE SIDES OF THE SHEAVE CARRIAGE, SAID SECOND CABLE MEANS ALSO PASSING AROUND THE PAIR OF SHEAVES AT THE OTHER END OF THE TRACK STRUCTURE AS WELL AS A STATIONARY SHEAVE AT SAID OTHER END OF THE TRACK STRUCTURE, THE ARRANGEMENT BEING SUCH THAT MOVEMENT OF THE SHEAVE CARRIAGE IN ONE DIRECTION WILL CAUSE SAID DRAW CARRIAGE TO MOVE IN THE OPPOSITE DIRECTION.

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