US2917161A - Draw buggy - Google Patents

Description

W. E. KERR Dec. 15, 1959 DRAW BUGGY 6 Sheets-Sheet 1 Filed May 26, 1954 INVENTOR. WALLACE E. KERR ATTOR E) W. E. KERR DRAW BUGGY Dec. 15, 1959 6 Sheets-Sheet 2 Filed May 26, 1954 INVENTOR WALLACE E. KERR ATTORNEY Dec. 15, 1959 w. E. KERR 2,917,161

DRAW BUGGY Filed May 26, 1954 6 Sheets-Sheet 3 IN V EN TOR.

WALLACE E. KERR BY ww/ ATTORNEY Dec. 15, 1959 Filed May 26, 1954' W. E. KERR DRAW BUGGY FLL'Y4? 6 Sheets-Sheet 4 INVENTOR. WALLACE E. KERR A T TOR/VE Y W. E. KERR DRAW BUGGY Dec. 15, 1959 6 Sheets-Sheet 6 Filed May 26, 1954 I N V EN TOR. Wallace E MW:

Unit tew Pawnt i Q DRAW BUGGY Wallace n. Kai, Poland, on... Application May 26, 1954, Serial No. 432,38ll

10' cl ims. or, zs-3 V f v This invention relates to "a drawbench ingeneral and more particularly to an improved draw buggy 'for' travel along a draw bench for the cold drawing and/or cold forming of various, metallic shapes.

The principal object of the invention is the provision of an improved draw buggy particularly adapted'for the cold drawing and/or forming of architectural metallic shapes and the like. I s

A further object ofthe invention is the provision of an improved draw buggy for a draw bench, the draw buggy incorporating hydraulically actuated grip closing means capable ,of flattening wavy stock ends or crushing the stock end until a non-yielding grip is attained.

A still further object of the invention is the provision of an improved grip buggy for operation on a draw bench and incorporating self-contained hydraulic means for actuating the grip bitsthereof. t o I c A still further object of the invention is the provision of an improveddraw buggy incorporating self-contained hydraulic actuating mechanism enabling the grip bits to be opened with respect to the stock being drawnwhile drawing force is applied to the stock. A still further object of the invention is'the' provision of an improved draw buggy incorporating grip 7 bits capable of gripping in any plane from vertical to 'horizontal.

A still further object ofthe invention is'the provision of an improved draw buggy incorporatingfgrip bits moy able laterally'to efiect gripping ofthe ,stockj'whileimmovable axially with respect to the dr awbug'gyig A still further object of the invention is the provision of a draw buggy having a self-centering grip bit for gripping movement onto the stock to be drawn, a second grip bit member for equal opposed movement onto said stock and a movement equalizing device intermediate the grip bits and subject only to force arising consequent to the weight and friction forces related to said grip bits. V A still further object of the invention is the provision of an improved draw buggy incorporating means for manipulating a sustaining plug for insertion into the stock to be drawn and a knocker to facilitate extracting said sustaining plug from the stock drawn. t

A still further object ofthe invention is theprovision I I of an improved draw buggy in which the grips and draw bench chain engaging means may be remotely'controlled. The draw buggy disclosed herein is particularly adapted for use in the cold drawing and/or cold forming of architectural shapes such as, by way of example',- the bronze or aluminum window easements now beingused in new building constructions. The drawing of such-shapes may be solely for the purpose of truing an interlock tongue -or socket or for closing an open extrusion, locking a lock seam or for smoothing the extrusion.

The draw buggy is particularly useful in drawing structural shapes such as an I or an H beam which may have each of its half flanges directed angularly outwardly to favor extrusion, the draw through an appropriate die reudering theshape accurate I or H form.

2,917,161 Patented Dec. 15, 1959 "quires' a considerable variation as to the necessary extent of grip bit closing in order that the various sections may be accommodated and the draw buggy disclosed herein incorporates hydraulically actuated grip bits capable of flattening stock ends or crushing the stock ends until a non-yielding grip is attained, with or without a sustaining plug. Y

Those skilled in the art will recognize that the draw buggy is particularly adapted to the handling of shapes which may be produced within the 24 inch die circle of the heavy stock extrusion press. It will further be observed that the draw buggy disclosed herein is novel in that the body-or truck thereof constitutes a welded steel oil reservoir capable ofmaintaining oil tightness as it is relieved of the direct drawing forces inherent in draw buggyconstructions heretofore known in the art.

Additionally, the draw buggy disclosed herein introduces a novel device in that an electrically actuated knocker is incorporated for freeing a sustaining plug or device from the hollow drawn shape by remote control. The self-contained hydraulic actuating means of the draw buggyis' also particularly adaptable to remote control and means are incorporated rendering the device entirely capable of remote actuation from a fixed operators position on a draw bench.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts in the details" of construction and hereinafter described and claimed, it being the intention to cover' all changes and modifications of the example of the invention herein chosen for purposes of the disclosure,-which do not constitut e'departure's from the spirit and scope of the invention.

The invention is illustrated in the accompanyingdrawing, wherein:

Figure 1 is a top plan view of the draw buggy.

' Figure 2 is a side elevation of the draw buggy.

Figure 3 is an end elevation of the draw buggy taken on line 3-3 of Figure 2.

Figure 4 is an enlarged transverse section of the draw buggy taken on line 44 of Figure 5.

Figure 5 is a longitudinal cross section of the draw y- Figure 6 isa longitudinal section taken through a portion of the grip bits of the draw buggy shown in Figure 5 and taken on line 6-6 thereof. a

Figure 7 is an enlarged end elevation of the draw buggy.

' Figure 8 is a longitudinal section taken on line 8-8 of Figure 5.

Figure 9 is a wiring diagram of the remote control system for actuating the draw buggy.

Figure 10 is a schematic view of the hydraulic system of the draw buggy. I I

. Figure 11 is a vertical section on line 11-,11 of Figure 5.

Figure 12 is a vertical section of a modified structure.

By referring to the drawings and Figures 1, 2, 3 and 4 in particular it will be observed that the draw buggy comprises a tank-like body 10 having bifurcated end sections 11, 11, defining a longitudinally extending passageway 12 in which a hook 13 is positioned longitu dinally with .oneend thereof extending outwardly therefrom for engagement with a motivating draw bench chain 14.

.The hook 13 .is pivotally mounted on a transverse shaft 15 which latter is affixed in the horizontal aligned bores extending transversely ofthe sections 11, 11 of the .body 10and whichengages the transverse aligned bores of, prevents rotation thereof, and vertically supports one 'end of "a coupling 16, the other end of which extends -withina trunnion 17 and which trunnion 17 rotatably :engages a'collar of the coupling 16 through an annularly flanged end 18, .as best shown in Figure of the drawings Thetrunnion 17 is rotatably positioned within the bore in in cylindrical body 19 forming apart of the tank-like body .10 and positioned.longitudinally thereof. "A forward end ofthe trunnion 17, comprising that end thereof oppositev from the end which is pivotally connected to the hook 13, extends outwardly of the cylindrical body 19 and carries a face plate 20 likewise rotatable therewith.

By. referring again to Figures 1 through 4 of the drawings it willbe seenthat the trunnion 17 extends through the forward wall A and rearward wall 103 of the tank-like body 10 and that tension conveyed thereto by the hook 13, as from the draw bench chain 14, will thus .be carried free of the tank-like body 10 of the draw buggy and directly to the face plate 20, which structure serves tomount the actual grip bit assembly, as herein- .after described, the trunnion 17 serving as a drawbar. The trunnion 17 and the face plate and the grip bit assembly thereon may'be rotatively selectively indexed with respect'thereto and thereupon nonrotatively secured -.to-the adjacent forward wall 10A of the tank-like body '10'by-means of aremovable bolt 11A engaging openings 11B insaid forward wall 10A.

Thetank-like body10 comprises a reservoir in which a suitable fluid medium is carried and the tank-like body 10 also forms a support for an electric motor M which .ismountedthereon and which in turn supports a pair of fluid pumps 21, 21.

The fluid pumps 21, 21am connected by tubular membersfnotshown) with the reservoir formed by the tanklike body 10'so that hydraulic fluid obtained therefrom tmay zbe directedthereby to. points of use ontthe draw -buggy. as hereinafter; disclosed. Specifically, one ofsuch points of use comprises a hydraulic piston and cylinder ,assernbly22 which ispositioned on one side of the tanklike body 10 and in longitudinal alignment with an actuating bar 23 which is also mounted on the same side of the tank-like body 10 by means of a pair of spaced . supportingbrackets 24, 24.

The actuating bar 23, which is adjustably spring urged rinonedirection by a spring 25, is pivotally connected as at 26 to a transverse shaft 27 which forms a part of a latch mechanism 28, the lower portion of which is pivoted as at 29 to the bifurcated end sections 11 of the tank-like body10. The book 13 is provided withan offset portion spaced wheels 32 and 33 which engage the longitudinal flanges 53, 53 on the draw bench as best shown in the cross sectional elevations .of Figures 3 and 7 of the drawings.

In order that the draw buggy may be engaged upon stock to be drawn and thereby carry out its intended purpose, the face plate 20 on the forward end of the rotatable trunnion 17 (which extends through the walls 10A and 10B of the tank-like body 10 of the draw buggy) is arranged to movably support a pair of opposed grip bits 34 and 35, the grip bit 35 being mounted in laterally movable "relation to the face plate 20 and the grip bit 34 mounted in opposed movable relation with respect to the grip bit 35 and laterally with respect to the face plate 20.

The face plate 20 when indexed to that selected position wherein the grip bits 34 and 35 will move vertically, is

provided with a forwardly extending-vertically positioned portion 36-having vertically positioned, oppositely disposed channels-37, 37 in its Opposite sides, as best shown in Figures 5 and 6 of the drawings. By referring thereto it will be observed that the-grip bit 34 is part of a grip bit mounting assemblyincluding a mounting member 38 which directly mounts the grip bit 34 and which in turn is attached to a piston rod 39 which extends into a :hydraulic cylinder 40'which constitutes a commercially available double acting reciprocating fluid pressure motor where within the piston rod 39 is affixed tothe piston 39A whereby hydraulic pressure selectively applied 30 which is normally'carried' on a seat 31 on thelatch mechanism 28 and the hook 13. thereby held in elevated relation-with respectto the chain14.

At such time as it is desired to engage the hook 13 on the chain-14,themeans-controlling the hydraulic piston and cylinder assembly 22 are actuated, as hereinafter described, to causethe movement of the latch'mechanism 28 to disengage the seat 31 from beneath .the offset portion 30 and'thereby permit the hook '13 to drop and engage the chain 14. When the chain is under tension. it tends to rise and the offset portion 30 is therethereto effects reciprocation of said grip 'bit assembly ,and which cylinder 40-in turn is affixed to-grip bit -mounting;frame 41. The grip bit mounting frame 41 is provided with oppositely disposed vertically extending channels 42, 42 which are cooperativewith the channels .37, v37 heretofore referred to so that a plurality of ;rollers 43, 43 v positioned in the vertical fpassageways ternate rollers-engage oppositesurfaces: and thus providesuitable bearing surfaces with respect to the horizontal and vertical loads.

.A similar arrangement of vertical channels 44,44 and 45,45 are "respectively formedin the frame 41 and the mounting member 38,-as best shown in Figures 5 and;6 of the -drawings,,and thus movably position the mount- .ing member 38 in fixed alignment with the remainder of the grip .bit assembly, .and the grip bit '35 in particular. A plurality of roller bearings 46, 46 are positioned instaggered relationin the opposed-channels44,-44 and 45, 4510 take the tension conveyed thereto and the horizontal and vertical'thrust occasioned by the movement of the mounting member 38 and its grip bit 34.

The mounting member 38 which carries the grip bit 34 and the grip bitmounting frame 41-are interconnected for simultaneous equalopposed travel with respect to the portion 36' by a toothed pinion 20A rotatively mounted on the-fulcrum 20B of the portion 36 of face plate .20and engaging on its opposite sides, toothed racks-38A and 41A-formedon the mounting member 38 and grip bit'mounting frame 41, respectively, as best illustrated in Figures 5,-.6, 7 and ll of the drawings.

,It'will thusbe seen that thezgrip bitmounting assem- .bly including the mounting member 38. carrying the grip bit 34, and the frame 41 are movable laterally with respect to the face plate 20 and that the face plate 20 carrying the grip bit mounting assembly just-referred to is movable circumferentially based on the axis of the trunnion 17.

Such alternate "mounting positions are shown in Fighydraulic cylinder 40 in alternate horizontal position so that the grip bits are movable horizontally.

In Figure 3 of the drawings solid lines show the vertical position of the cylinder 40 and grip bits while dotted lines show a diagonal intermediate position as well as a horizontal position of this portion of the apparatus.

It will thus occur to those skilled in the art that the stock to be engaged by the grip bits 34. and 35 may be of any shape or contour and that the complete adjustability of positioning of the grip bits 34 and 35 enable the same to be effectively engaged upon the stock through a simple adjustment of the grip bit assembly of the buggy. It will also be observed that in each instance the hydraulic cylinder 40 and its piston 39A and piston rod 39 which operatively engage the grip bit mounting member 38 enable the same to be retracted or advanced with respect to the grip bit 35 at will.

Upon the grip bits 34 and 35 gripping the stock, fluid pressure within the cylinder 40 exerts force onto the piston 39A, thence by piston rod 39, mounting member 38, and grip bit 34 to the stock and equally and oppositely the pressure exerts force onto the cylinder 40, thence by the grip bit mounting frame 41 and the grip bit 35 to the stock. This transmission of gripping force by the two respective force trains to the stock has in no way entailed the pinion 20A nor the racks 38A and 41A meshed therewith. The pinion 20A is subjected to other reactive forces arising from the weight of the moving members comprising the two force trains, from resulting friction, and from extraneous load, if any.

, Further, the pinion 20A rotatively mounted on the fulcrum 20B of the portion 36'and meshing on its opposite sides, respectively, the rack 38A connected with the piston 39A ad the rack 41A connected with the cy1in der 40, so controls the motion with respect to the portion 36, of each of the two grip bits 34 and 35 to be one-half that of the piston 39A with respect to the cylinder 40, or, otherwise stated, the movement of the piston 39A with respect to its cylinder 40 is equal to the sum of movements of each of the grip bits 34 and 35 with respect to the portion 36. r

The fluid pressure applies an action force onto the piston 39A for effecting action thereof and likewise of its connected grip bit 34 and rack 38A, while simultaneously the fluid pressure reaction force is applied onto the cylinder 40 for effecting opposed action thereof and likewise of its connected grip bit 35 and rack 41A. The pinion 20A rotatively mounted on its fulcrum 20B of the portion 36 and intervening therebetween the racks 38A and 41A, imposes equal action to these respective racks. Thereby the action transmitted to the grip bit 34 is equal to the reaction transmitted to the grip bit 35 and the sum of the extent of the said action and reaction with respect to the portion 36 is equal to the extent of action of the piston 39A with respect to the cylinder 40. v

Still referring to Figures 2, Sand 8 of the drawings, it will be seen that means is provided for introducing a sustaining plug S into the end of a tubular stock to to conform to the interior contour of the hollow stock and preferably has a liberal chamfer to facilitate its entry into the tubular stock end.

In Figures 3, 5, 8 and 11 a manipulator for the sustaining plug S is illustrated and comprises a manipulating arm 88 loosely engaged upon the shaft 47 and extending laterally and outwardly through an opening in the mounting frame 41. The manipulating arm 88 permits the operator to move the shaft 47 transversely and hence the sustaining plug S as may be necessary in aligning it with the end of the tubular stock into which it is to be inserted prior to a drawing operation. A mating hole 88A in the lever 88 through which the shaft 47 extends, being slightly larger thanthe shaft 47 to afford the loose engagement, also permits manually cramping the lever ontothe shaft'to cfiect a degree of rotation thereof and the sustainer plugs mounted thereon. However, the otherwise normally loose engagement averts positive impact being transmitted to the lever 88.

An electric power knocker apparatus such as is commercially available is generally indicated by the numeral 49 and the respective cylindrical end closures thereof are slidably mounted between opposed coil springs 50, 50 respectively seated onto the axially fixed and spaced abutments 17A and 17 B within the trunnion 17 and where within the knocker percussion element is capable of imparting rapid percussive blows directed toward the anvil 49A Within the loop of a metallic band 49B extending slidablythrough apertures through the end closures, and which band transmits the resulting impact to the socket 49C within the opposite loop of the band 49B. The shaft 47 extends loosely through the socket and terminates in the form of an integral collar or button 47A constantly urged' to tend to abut onto the adjacent end of the socket 490 by the expansion coil spring 49D interposed intermediate the adjacent end closure of the knocker'49 and the button 47A. Further, this urging effort so applied onto the socket 49C within the loop of the band 49B will transmit this urging effort by way of the band 49B to the anvil 49A within the first mentioned loop of the band 49B whereby the anvil is urged toward and to re-establish contact with the percussion element of the knocker to so transmit successive blows. The components 49A, 49B and 49C constitute a unit transmitting the percussive impact to the button 47A and thence to the shaft 47 to the sustaining plug S and the spring 49D thereupon serves to resiliently restore the contactual continuity to transmit the impact of a succeeding percussive blow. The sustaining plug S being subjected to a series of percussive impacts directed toward the right, as in Figure 5, and the intervening series of resilient restorative efforts directed toward the left in combination tend to step a tube-like stock length from and so extract therefrom the sustaining plug S by reason of the relatively negligible mass inertia of the plug S with respect to the axial mass inertia of the stock'length.

An electrical circuit for energizing the knocker apparatus 49 is established by appropriate wiring (not shown) which enters the hollow trunnion 17 by way of a passageway 51 formed in the coupling 16, as best shown in Figure 5 of the drawings. The knocker apparatus 49 is also illustrated symbolically in Figure 9 of the drawings wherein its two actuating coils are indicated by the numerals and 86, respectively. In the diagram of Figure 9.the power supply circuit for the knocker 49 includes double dry plate rectifiers 87.

It will occur to those skilled in the art that it is necessary to extend electrical circuits along the draw bench on which the draw buggy herein disclosed operates and as illustrated in Figures 3 and 9 of the drawings. It will also be obvious that means is necessarily provided for engaging the electrical circuits extended along the draw bench to, in effect, extend the same to the actuating portions of the draw buggy.

In Figure 3 of the drawings a cross sectional elevation of a typical draw benchis'shownwith the principalvertical supports being indicated *by the numerals "52, 52 carrying flanged guide members '53, 53. Thelongitudinally and transversely spaced pairs ofwheels32 and 33 of thedraw buggy engage the flanged members :53, 53 which serve to guide the draw .buggy'along the draw bench, all asknownin the art.

lu-Figure 3 of thedrawings a limit switch construction is illustrated and generally-indicated by the numeral=54 and-:is'one'of several whichmay-be employed in conjunction with theoperationofthe drawbuggy along the draw bench, alsoas known in the art.

Extending longitudinally along the draw bench there is an arrangement 'of four conductors 55, 56, 57 and 58 arranged in'a boX-like-enclosure openalong its' bottom and in which a trolley i device (not shown) may be mounted and-moved along by an arm such as connected with the draw' buggy. The trolley device-symbolically shown in Figure 9 of the drawings incorporates four conductor engaging members 6%), 61, 62 and 63 which engage the conductors 55, 56, 57 and 58 respectively.

By referring to Figure 9 of the drawings it will be seen that the conductors 55 and 58 comprise a circuit for the actuation of the knocker 49 and that the circuit is controlled by a switch 64. The conductor 58 is in connection with one side of =a-power supply line 55, the other side of WillCd comprises a line 65 in connection with the conductor 56 so that upon closing of the switch 64-, current flows'between the conductors 55 and 58 by way of the conductor engaging member 63 and associated conductor 63A to the coils S5 and 86 through the rectifiers 87 and to the conductor 55 by way of the conductor engaging member 60 and its associated conductor GilA.

The motorM which actuates the fluid pumps 21, 21 is also supplied through these electrical conductors and specifically through conductors 55 and 56 by way of the conductor engaging members 6%) and 61 and their associated conductors 60A and 61A.

Additionally, the operation of the hydraulic cylinder 40 controlling the movement of the grip bits 34 and 35 is controlled through these electrical circuits and specifically through a solenoid valve symbolically illustrated at 67 and obtains its power supply from the conductors 56 and 57- by way of the conductor engaging members 61 and 62 and their associated conductors 61A and 62A. The circuit from the conductor. 57 tolthe 'conductor55 is controlled by a switch 68 which, like-the switch'-i, is located at the operators stand and the various operative portions ofthe draw buggy are thereby completely remotely controlled through the arrangement disclosed. The actuating means for the grip bits 34*and 35, which are self-centering with respect to the axis of the trunnion 17 by reason of their-mounting in movable relation to the face plate 29 of the trunnion .17, comprises the hydraulic cylinder 40, the piston 39A and piston rod 39 of which are directly connected with the gr'ip'bit mounting member 33 which holds the grip bit 34.

It will thus be seen that by supplying the hydraulic cylinder 4% with appropriate hydraulic fluid under pressure, the action of the grip :bits may be controlled. The pumps 21, 21 heretofore :referred to in connection with Figures 1 and 2 of the'drawings and as shown symbolicallyin Figure 10, are both actuated by the motor M which is in turn :mounted von the draw buggy. One of the pumps 21 supplies hydraulic fluid under relatively low pressure totaisupply line 69, as seen in Figure of the drawings, which vsupply line communicates with a pressure gauge 70 and a spring biased check valve 71 which generally maintains 50 p.s.i. in the line 69 delivering hydraulic fluid in excess of the desired pressure to the reservoir of the tank-like body it The other of .the pumps 21 supplies hydraulic fluid under high pressure; for example 200 p.s.i., to supply line ,72iwl1ich=.conm1unicates with,avguage 73 and an adjustable-relief valve 74. The high pressure liner72 extends beyond the relief =valvel74 to communicate with the upperendof the hydraulic cylinder 40. :A by-pass line 75 establishes communication between the high pressure line 72 r and the low pressure line 69 by way 40f a ispring biased-check"valve A secondary by-pass'line'77 establishescommunicationfrorn the high pressure 1ine 72 to the reservoir of the tank-like body 10 by way of a spring biased two' way solenoid valve 67. The relief valve-74 also communicates with the reservoir of the tank-like body 10 by wayofa line'79.

Hydraulic fluidfor the pumps 21, His obtained from the reservoir-of thetank-likebody' 10 by a suction line 80. -An-extension '69A'Off'ih6 'low pressure line 69c tends to thelower end of the hydraulic cylinder 40 and a secondary extension 69B extends to the outer end of the hydraulic cylinder 22. A hydraulic 'line 690 extends from the low pressure line '69 through a spring biased three-waymanual valve 81 to the opposite or' inward end of the hydraulic'cylinder 22 and the manual valve 81 also communicates with the reservoir of the tank-like-body*10 byway of 'a-line 82.

'It will'be recognized by those skilled in the art that due to the movablemounting of the hydrauliccylinder 4t) on-the grip bit assembly of the draw buggy, as hereinbefore described, portions of the line'72 and'69A are necessarily flexibleand couplers S3 and'84 are accordingly shown in the symbolic diagram of Figure 10 of the drawings "as connecting the flexible lines with the hydraulic pressure line heretofore referred'to.

In-operating the buggyalong a more or less conventional draw benchmodifiedto include the conductors 55, 56, 5.7"and 58,"as heretofore described, those skilled in the art will'recognize Tthatthe draw buggy may be provided'with conventional cablereturnmeans (not shown), if desired, so that it may be returned 'by the operator toia'positioniadjacem the'he'ad stand of the draw'bench where "stock such as an extruded'shape to be drawn :is passed through a die 'and positioned for engagement .betweenjthe' grip bits "34 'and 35. Such stock may be practically any shape and sizeincluding, for example, a'hollow ribbed section, portions of which are .considerably oif center with respect to the longitudinal center of. the trunnion 17 of the draw'rbuggy.

The switch 63controlsthe two-Way solenoid valve 67 which is thereby positioned to permit hydraulic fiuid under high pressure 'tofiow through the line 72 to the upper end oftthel hydraulic-cylinder 40 where it causes the piston 39A and piston rod 39 thereof to move the group bit 34 into engagement with the stock to'be'drawn, and simultaneously the cylinder 4b with the frame 41 moves the grip bit35 into engagement with the stock to be drawn. in the event the stockis off-center, the closure of the g riplbits '34 and 35 will forcefully center the stockvend on'the draw line.

It will'be observed that the action of the grip bits ,34 and is normal with respect to the longitudinal axis of the draw'buggy and stock and also that the springs 50, 50 respectively seated .onto the abutments 17A and 173 in conjunction with theknocker 49, the unit comprised of the components 49A, .49B'and 49C, and with the shaft 47 constitute anchor means tending to designate .a definite axial locus .of the sustaining plug S within the area of the grip bits 34 and '35. Note that the closing action of the grip bits 34 and 35 onto the stock end and the compacting of the stock end onto the anchored sustainingplug 'Sdoes not entail axial strain. When necessary, the movement of the .grip bin may be horizontal or vertical or any angle therebetween so that the positioning of the grip bits 34-and 35 conforms with the particular position andshape-ofthe stock to be drawn.

When the grip bits 34and 35 have engaged the stock and in the event of a tubular section, a sustainingplug,

having been previously introduced into the endthereof to support the stock against'undue crushing, the operator moves the manual valve 81' to deliver hydraulic fluid under low pressure from one of the pumps 21 through the line 69 and 69C to the hydraulic cylinder 22, the piston of which then moves out to engage the actuating bar 23 and thereby move the latch mechanism 28 to permit the book 13 to fall and engage the draw bench chain 14 whereupon the buggy moves along the draw bench away from the die stand drawing the stock through the die, as is customary in a draw bench operation.

I When the draw is completed and the draw buggy is at some distance away from the head stand of the draw bench, the operator releases'the switch 68 which opens the-two-way solenoid valve 67 and permits the high pressure fluid to be delivered directly to the reservoir of the tank-like body by way of the line 77- and simultaneously permits the hydraulic fluid under low pressure in the lines 69 and 69A to enter the hydraulic cylinder 40 through its lower port and move-the grip bit 34 away from the grip bit 35, thus freeing the stock.

In the event the stock is securely engaged on the'sustaining plug, the operator then closes the switch 64 actuating the knocker 49 which through the shaft 47 engages the sustaining plug S within the stock and impacts the same to insure the release thereof from the stock. The stock may then drop free from the draw buggy and its grip bits 34 and 35 whereupon conventional return means (not shown) may be utilized to return the draw buggy to a point adjacent the die stand for a subsequent operation.

Modifications in the structure disclosed will occur to those skilled in the art and one such modification is illustrated in Figure 1 2 of the drawings wherein a draw buggy 110 is positioned on a draw bench 153 by way of a plurality of wheels 133 and incorporates a trunnion (not shown) comparable with that heretofore described in connection with Figures 1 through 11 of the drawings. The trunnion has a face plate with the portion includ-- ing member 138 and the grip bit mounting frame 141A are movably positioned for opposed lateral movement with respect'to the axis of the draw buggy and trunnion therein. v 1 A hydraulic cylinder 140 is affixed onto the grip bit mounting frame 141A and its piston 139A and piston rod 139 integrant is connected to the grip bit mounting member 138. Members 120A oscillating about a fixed fulcrum 120B of a portion analagous with the portion 36 of the Figure 6 are disposed adjacent the grip bits mounting member 138 and portion 141 and each of the members has one interconnection 141C and one interconnection 138A, respectively pivotally connected to arms at radially opposed points equidistant from sa-id fulcrum by the pivot pins 120C, 120C, each interconnection 138A and 141C respectively pivotally connecting with the grip bit mounting member 138 by the pivot pins 138B, 138B and the grip bit portion 141 by the pivot pins 141B, 141B imposing synchronized and equidistant moving of said cylinder 140 and piston 139A and thusactiug to cause a self centering of the bit mounting member 138 and portion 141 and the trip bits mounted respectively thereon likewise to eifect centering onto the stock to be drawn. Figure l2 discloses that geometry of the motion of one interconnection 141C, one member 120A, and one interconnection 138A duplicates the motion of the mounting member 138 with respect to the portion 141 as obtained with the two interconnections 141C,.two members 120A,

and two members 138A. The latter disposition, shown in Figure 12 of the drawings, obviates the imposition of a force couple.

-It will thus beseen that the mechanical interconnection of the grip bit mounting member 138 and portion 141 insures the self-centering of the grip bits on the stock consequent to the extent of motion of the piston 139A with its grip bit mounting member 138 and synchronized equal and opposite extent of motion of the cylinder 140 and its grip bit mounting frame 141A with respect to the fulcrum 1203 of the portion analogous with the portion 36 of the Figure 6. I

It will thus be seen that the several objects of the invention have been met by the draw buggy disclosed herein.

Having thus described my invention, what I claims-is:

1. A draw buggy of'a draw bench for drawing elongated hollow stock, the draw buggy comprising a body having a bore positioned longitudinally thereof defining the longitudinal axis of the draw buggy, and including abutments longitudinally affixed with respect thereto and further including mounting structure for a grip bit assembly, a pair of opposed grip bits on said mounting structure for opposed and lateralmovement to effect gripping therebetween a stock end of said hollow stock to be generally in alignment with said axis; an anchor means fora sustaining plug; a sustaining plug, for insertion into said hollow stock end, mounted onto said anchor means and said anchor means being generally aligned with said axis and extending longitudinally there of'to within said bore whereby said anchor means is thereby seated onto said abutments, thereby longitudinally retainingsaid sustaining plug.

2. A draw buggy of a draw bench fordrawing elongated hollow stock, the draw buggy comprisin a body having a bore positioned longitudinally thereof and defining the longitudinal axis of the draw buggy, and ineluding abutments longitudinally aflixed with respect thereto and further including mounting structure for a grip bit assembly, a pair of opposed grip bits on said mounting structure for opposed lateral movement to effect gripping therebetween a stock end of said hollow stock to be generally in alignment with said axis; a sustaining plug for insertion within said hollow stock end, said sustaining plug being mounted onto a shaft generally aligned with'said axis and extending longitudinally thereof to within said bore andthere within through a socket and there terminating in the form of an integral button abutting onto said socket, the latter and also an anvil being components of a unit extending further along said axis; a knocker generally aligned with said axis and seated onto said abutments for imparting percussive blows directed away from said stock end and onto said anvil component of said unit, which unit and said shaft having a bore positioned longitudinally thereof defining the longitudinal axis of the draw buggy, and including axially fixed abutments and further including mounting structure for a grip bit assembly and therewith a pair of opposed grip bits for opposed lateral movement to effect gripping therebetween a stock end of said hollow stock to be generally in' alignment with said axis, a sustaining plug for insertion into said hollow stock end, said sustaining plug being mounted onto a shaft generally aligned with said axis and extending longitudinally thereof 'to within said bore and therewithin through a socket and there terminating in the form of an integral button abutting onto said socket, the latter and an anvil being each disposed within a respective loop at the opposite extremities of a band, said bushing, anvil, and band being components of a unit; a power knocker disposed within said unit, generally aligned with said axis, and seated onto said abutments for imparting percussive blows directed away from said stock endand ontothe contactin anvil of said unit which transmits the percussive impact to the button and thence by the shaft to the sustaining plug, to impact said sustaining plug axially from said hollow stock end.

4. Theimprovement-in a draw buggy set. forthrin claim 3 and further including:an'expansion'spring interposed between said power knocker and said button, to restore said abutting and contacting percussive impacting conitinuity therebetween'said button and said knocker.

5. A draw buggy of a draw bench for drawing elongated hollow stock, the draw buggy comprising a body having a bore positioned longitudinally thereof defining the longitudinal axis of the draw bug and including abutments longitudinallyaffixed with respect thereto and further including mountingzstructure for a grip bit assembly and therewith a pair of opposed grip bits for opposed and lateral movement to effect gripping there- .betwecna stock end oftsaid hollow stock to be. generally in alignment with said axis and a sustaining plug-for insertion within said hollow stock end, said sustaining plug being mounted ontoa shaft generally aligned with said .axis and extending longitudinally thereof to withinsaid bore and there within loosely through a socket'and there terminating in the form of an "integral button abutting onto said socket, said socket being a component of an anchor means seated onto said abutments and said mounting structure providing an openingfor thelateral protrusion of a manipulating arm, said shaft extending loosely through a mating hole in said arm and the latter protrud- -ingrlaterally to be manually grasped to engage the shaft to effect transverse and/ortrotative manipulation of said sustaining plug. 7

The embodiment of claim 5 wherein 'the'anchor means includes a power knocker for directing percussive blows onto the anvil component of a unit, the latter transmitting the resulting percussive impacts to :said shaft and thence to said sustaining plug, the loosenessof the shaft-extending through the hole in said manipulatingarm averting positive impact thereto,

7. Agrip of the self-centering type comprising a portion and a frame, each providing cooperative passageways affording lateral movement of said frame with respect to said portion but otherwise effectively securing said frame to said portion; a first grip bit mounted withinone tlateral'extremity of the frame and a cylinder of a reciprocating fluid pressure motor aflixed onto the opposite lateral extremity of said frame; its axis of reciprocation being parallel with said passageways and directed generally toward said grip bit; a mounting member and said frameeach providing cooperative channels parallel with :said passageways affording aligned movement but other- -wise effectively securing saidmounting member-With're- *spect to said frame, .a second grip bit being a part of said mounting member and'disposed in juxtaposition to said first grip bit; a piston rod attached to the mounting -member and extending'coaxially'with said axis :into :said

.cylinder wherewithin the piston rod is afiixed to a piston; a toothed rack extending parallelwith said passageways and being an integrant with said frame, :a second rack extending parallel with said channels and beingan integrant with said mounting member, an intervening toothed pinion meshing oppositely with the respective racks and rotatively mounted on a fulcrum of saidlportion; the said racks and pinion constituting an organization constraining the movement of said cylinder and said piston to be synchronized and opposite with respect ;to said portion and to be simultaneous means to :selectively supplyfiuid pressure tosaid motor to so move said cylinder, frame and said first grip bit with respect to said portion and to so move'said piston, piston rod, mounting member andsecond grip bit with respect to .saidportion.

8. A grip of the self-centering type comprising a por- .tion having a fulcrum and,passageways;-a toothed pinion rotatably mounted :on said fulcrum, a first unit comprising a frame, a first-grip bit mounted within one lateral extremity of said frameand a cylinder of a reciprocating fluid pressure motorafiixed to the opposite lateral 'extremity of said frame with its axis of reciprocation being directed generally toward said grip bit, a first toothed rack integrant with said frame and meshing into said pinion, channels and passageways formed in said frame, said axis, rack, channels and passageways extending parallel with and the latter cooperating with said passageways of said portion to afford lateral movement of but otherwise effectively securing said first unit with respect to said portion; a second unit comprising a mounting member having channels cooperating with the first said channels and'affordingaligned movement with, but otherwisese curing, said mounting-member with respect to saidframe,

a second-toothed rack integrant with said mounting member and meshing into said'pinion in counterposition'with respect to said'first toothed rack, a second grip bit being a part of said mounting member and disposed injuxtaposition with said firstgrip bit of said first unit, a piston rod attached to said mounting member and extending coaxially with said axis into the cylinder of said first unit ment of said second unit-and said reaction force effecting opposing movement of said first unit, said racks and intermeshed pinion constraining said movements to be synchronized and movement of the piston of said second unit to be equal and opposite to the movement of said cylinder of said first unit with respect to said portion.

9. A grip of the self-centering type comprising a portion providing a fulcrum, a toothed pinion rotatively mounted thereon, and passageways in said portion; a first unit comprising a frame, a first grip bit mounted within one lateral extremity of the frame and a cylinder of a reciprocating fluid pressure motor affixed onto the opposite lateral extremity of the frame with its axis of reciprocation being directed generally toward said grip bit, a first toothed rack integrant with the frame and meshing into said pinion, channels and passageways formed in said frame, said axis, rack, channels, and passageways extending parallel with and the latter cooperating with said passageways of said portion to afford lateral movement of but otherwise effectively secure said first unit with respect .to said portion; a second unit comprising a mounting member having channels cooperating with the first said channels and affording aligned movement with but otherwise securing said mounting member with respect to said frame, a second toothed rack integrant with said mounting member and meshing into said pinion in counter'position with respect to said first toothed rack, a second grip bit being a part of said mounting member and disposed in juxtaposition withsaidfirst grip bit of said first unit, a piston rod attached to the mounting member and extending coaxially with said axis into .the cylinder of said first unit and wherewithin .it is afiixed to a piston; means to selectively supply fluid pressure to said motor to effect the movement of said first unit with its cylinder affixed thereto and opposed movement of said second unit with its piston afi'ixed thereto, the interaction of said pinion and said first rack controlling the extent of movement of said cylinder with respect to said portion and the interaction of said pinion and said second'rack controlling the extent of movement of said piston with respect to said portion.

10. A grip of the self-centering type comprising a portion having passageways and providing a fulcrum, amember mounted for oscillation thereon and having two arms each extending oppositely therefrom; a first unit .com-

prising a frame, a first grip bit mounted within an'adjacent lateral extremity of the frame and a cylinder of a reciprocating fluid pressure motor aflixed onto them:-

posite lateral extremity of the frame with its axis of reciprocation being directed generally toward said grip bit, a first interconnection pivotally interconnecting the said adjacent lateral extremity of the frame with one of said arms, channels and passageways formed in the frame, said axis, channels and passageways extending parallel with and the latter cooperating with the said passageways of the said portion to afford lateral movement of but otherwise eifectively secure said first unit with respect to said portion and said first interconnection extending generally parallel with respect to said passageways; a second unit comprising a mounting member providing channels cooperating with the first said channels and affording aligned movement with but otherwise securing said mounting member with respect to said frame, a second interconnection pivotally interconnecting said mounting member with the other of said arms and extending generally parallel with said passageways, a second grip bit being a part of said mounting member and disposed in juxtaposition with said first grip bit of said first unit, a piston rod connected to the mounting member and extending coaxially with said axis into the cylinder of said first unit and wherein it is integrant with a piston; means to selectively supply fluid pressure to said motor to effect the movement of said first unit with its cylinder afiixed thereto and opposed movement of the second unit with its piston connected thereto, the interaction of said first interconnection and arm of the member mounted for oscillation controlling the extent of movement of said cylinder with respect to said fulcrum and the interaction of said second interconnection and said other arm of the member mounted for oscillation controlling the extent of movement of said piston with respect to said fulcrum.

References Cited in the file of this patent UNITED STATES PATENTS 1,951,073 Wallis Mar. 13, 1934 1,973,031 Wrage Sept. 11, 1934 2,304,793 Bodine Dec. 15, 1942 2,679,177 Gepfert May 25, 1954 FOREIGN PATENTS 445,028 Germany June 2, 1927 569,934- Great Britain June 14, 1945 595,470 Great Britain Dec. 5, 1947

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