US2597500A - Apparatus for drawing elongated metal objects - Google Patents

Description

May 20, 1952 w. E. KERR APPARATUS FOR DRAWING ELONGATED METAL QBJECTS Filed April 28, 1948 3 Sheets-Sheet l INVENTOR. Wallace E. KP

QM NW WI v% Wm W. E. KERR May 20, 1952 APPARATUS FOR DRAWING ELONGATED METAL OBJECTS Filed April 28, 1948 5 Sheets-Sheet 2 l I IN V EN TOR. lVa/lac e E. Kerr.

May 20, 1952 w. E. KERR APPARATUS FOR DRAWING ELONGATED METAL OBJECTS Filed April 2a, 1948 3 Sheets-Sheet 3 INVENTOR lVa/Iace f. KPrr.

Patented May 20, 1952 UNITED STATJ'E'TS PATENT.

APPARATUS FDR'DRAWING EEONGATED METAL OBJECTS Walla-cell. :Kerr, Youngstown, Ohio,

AppIicatibn-ApriFZS, 1948;."S'eriali Noe-23384 8:Claims.. (CLZO'EV- Z This invention-relates to=-the meta1- drawing art and more particularl y to improved' 'methods apparatus for-drawing finite l'engths-ofmetai ohjectsthrough a die in such manner that. sub-* stantiai ly all scrap loss is eliminated and" in such manner" thatpreliminarypreparation of the blanks "to be drawn by pointing is obviated; While the invention to'be disclosed herein has some 'applic'zal-loil'ity in the field of" bar" drawing its greater and more important usefulness-is in tube drawing and greater emphasis willhccnrd-ihgiy be placed" herein! on the last mentioned use of the method and apparatus;-

I-t" has" heretofore-"been commonly proposed, in the metal drawingart, to provide pushing: grips inassociation with the drawing-die to extrude the leading ends of bl'ar-rks of uniform cross-sew tionai shape and dimension throughout-their length through the drawing die sufficiently-- toenable them to be-grippedwby thedraw carriage; the outward movement" of whichcompletes the drawing operation. It one of the objects of the-present inventionto-=providea novel and improved combination, imam-assembly of the nature indicated;- "of" pushing anti-pulling g-r-ip bits and mounting means therefor-whereby the indicated operation may be carried: outwith: greater facility and in a moredependable man-- ner.- Further, the 'novel combination of the grip hits while providingan entirely"practicablemachine yetnevertheless operativ'eto I draw the entire length of uniformly-crosssection blanks in-"a; dependabl'e mannerto provide a" finishedproduct-usable along its entire-length; thuseii'm mating any ne'e'd for cropping.

Another primary object of "the invention is: the provision of improved methods and apparatus. for drawingthe entire-longitudinal extent'of' uniformly cross-sectioned tuloeblanks in suchmannerthatthe finished product-is: of uniform: qualitythroughout its length, and free of grip marks;- -The process and apparatusofthis-in vention isequall'y' applicable in operations whereinn-the thicknessof the side wa ll or: thetuhe is reduced; or-in mere sinking operations:

more specific-- object of the invention is the provision in tube drawing apparatus of the character capablef drawingthe entire lengthoi a" uniformly cross-section blank ofan improved drivingarrangement for the pulling" grip--bits whereby the" initiationof the drawing operation isiaeilitated and-whereby static friction which may appear .betweenthe tube -and die is more readiiy'overcome; 7

Yet anotherobject of-the-inventionis-the-pro 2 vision: in tuberdrawingapparatustofi the :Lpush"- pointing typeofian -improvedkmandret hick is: operative during the ext-rudingon push-pointing phase: of a complete cycle to be: positioned 'im movingbut operative location withinnthe; die:

which has 1a:v furthennrelativeLymovable portion positionedwithimthe: tube blank opposite the: pushing grips." to prevent: collapsing: ofitherblank bythese A still furthers-object of th invention. isathe provision in: a; tube "drawing: systemzrofwithe kind operative to reduce theiside' .walli thickness iofi' a tube blank-1' throughout its entirev'long-itudinala extent; of an: improved plug: :nrandrelz; an; inn proved 'operatingszlme'chanismi fox'r'suchz mandrel; and Of I'IIIDIOVBIi methods forioperatingaand'con a trolling the: plug mandrel.

other specific obje'cts of the invention: are: the provision: of am improvedgmethod fior." gripping: an: extruded" endt-of at: tubebla'nki foncompletiom of: a tubedrawingoperation and ofpracticali apparatus for carrymgiout suchmethod;

Thesrabove; and; other :ol'ajeotss'and advantages; ofrtherinvention: wilirbenome apparent :upontcomsiderationi'of'ithe: following detailedispecificationz and; the. accompanyingsadrawings wherein. therei's. disclosed'iageertamz preferred: embodiment: of thezinven'tionz In the drawing:

Figures: 1; and-2' are sehematicarviewsr in: plan, of tube: drawing? app'aratusxconstnucteoi in;;a;c:- cordance withvthe principles; 0t invention; the viewsshowin'gs' the relativetmositionszofzthe parts at tww separate stages during the? draw ing cyc'ler,

Figure; Ia isxa fragmentary longitudinat sem tion of certainofi' the parts of the 'assemblyrof Figures 1' and: 21when :the; partsware-relativeliy positioned as, shownin'iiEigure 1.;

Figure 2a @is a viewsimilar-to-- Figure 10, but showing theparts' a'sfthey appearwherr the ma.- chineeistin the conditiomshown:in -Figure 2 Figures 3: and 4 are generally similar: to -Figures 1 'and12 'but show: -the relative positions of the parts: at thefthird' and fourth stage; respectively;of a 'c'omplete draiwmg cycle;

Figures 322:- and. 4a are enlarged fragmentary sections through certain of th parts of the-machine-as they are'rel'ativei'y positioned in -Fig=-'- ures 3- and4, respectively;-

Figure 5 is a view-similar to=Figure-1 but show-- ing' the parts in 1 the last stage of the cycle" of operationa Figure fia' isv afragmentary longitudinal see tion through certaimof the partsor -Fig; *5; Y

Figure 6 is a transverse section taken along the line 6-6 of Figure 5; and

Figure 7 is a transverse section through the drawing mandrel, the view being taken alon the line 1-4 of Figure 2a.

The illustrated apparatus of the invention comprises a draw carriage l mounting a grip block H and slidably supported on suitable ways |2 for movement toward and away from a die stand I3. While any suitable means may be employed to move the carriage |0 I preferably utilize a pair of double-acting hydraulic cylinders l4, the piston rods |5 of which extend outwardly to engage the carriage In to move the same away from and toward the die stand l3. Hydraulic fluid under pressure is arranged to be delivered to the rear ends of the cylinders |4 through conduits l6 to move the carriage |0 outwardly of the die while conduits l! are provided to admit hydraulic fluid under pressure to the forward end of the cylinders M to retract the carriage |0. Recessed in the die stand I3 is a drawing die l8.

Positioned rearwardly of the die stand l3 and intermediate the cylinders I4 is a push-pointing mechanism comprising a grip block 20 and a pair of rigidly interconnected cylinders 2| receivable over rams 22 which are fixed on a base 23 bearing fixed relation to the die stand l3 and the ways l2. It should also be understood that the cylinders M are also fixed on the base 23. The push-pointing mechanism 20-22 and all its appurtenances, many of which are not shown, may be of the kind fully disclosed and claimed in my co-pending application Ser. No. 490,060, filed June 8, 1943, and entitled Method and Apparatus for Drawing Tubes. As shown herein the grip block 20 slidably mounts a pair of serrated and wedgeshaped grip bits 24 and, as more fully explained in said co-pending application, the push-pointing mechanism includes means, not shown herein, for first closing the grip bits 24 onto the stock before hydraulic fluid pressure is admitted to the rams 22 to move the grip block 20 forwardly toward the die stand l3 and with means operative at the completion of a working stroke to open the grip bits 24 and to return the grip block back to its initial starting position. Hydraulic fluid pressure is admitted to the rams 22 through the conduits 25.

Slidably mounted in a wedge-shaped window formed in the grip block H of the carriage I0 is a pair of smooth faced wedge-shaped grip bits 26 which are contoured on their faces in the manner shown in Figure 6 to present four line contacts with a round bar or tubular member positioned between them. The absence of serrations or knurling on the gripping faces of the bits 26, however, requires the application of very extensive forces tending to move the grip bits toward each other to clamp a tube with sufiicient rigidity to draw the same through the die and to accomplish the application of such heavy forces. I position anti-friction rollers 21 intermediate the inclined outer surfaces of the grip bits 26 and the adjacent inclined side walls of the wedge-shaped opening in the grip block The grip bits 26 are, in actual practice, mounted in the grip block II in the manner more fully disclosed and claimed in my co-pending application Ser. No. 740,133, filed April 8, 1947, and entitled Metal Drawing Apparatus.

As shown more clearly in said co-pending application Ser. No. 740,133 the grip bits are guided for movement parallel with the respective inclined side walls of the opening in the block and in the apparatus disclosed herein means comprising a lever 28 is employed to move the grip bits 26 longitudinally to close and open the same with respect to work clamped therebetween. As shown more clearly in Figures 1a and 2a the enlarged ends of the bits 26 are pivotally connected to a slidable yoke 29 which in turn is arranged to be shifted back and forth by pivotal movement of the lever 28 about its pivotal anchorage l9.

The frame of carriage I0 is formed with a longitudinally extending bore 30 in which is slidably received a sleeve 3| having a slit end 32 adapted to be positioned between the grips 26 a shown in Figures 1a, 2a and 6. The longitudinally extending slots in the end 32 of the sleeve 3| divides this end into four equal circumferential segments and is shown more clearly in Figure 6; each of the segments is arranged to have at least line contact with the gripping face of the grips 26. For a purpose to be later described the end 32 of the sleeve 3| is retractible from the position intermediate the grips 26 and to provide for such, manipulation of the sleeve 3| I provide a lever 33 which is pivoted to the carriage H1 at 34. Slidably received in the sleeve 3| is an arbor 35 which is slidable into and out of position between the grip bits 26. For advancing and retracting the arbor 35 I provide a lever 36. It should be understood that the levers 28, 33 and 36 are included herein to facilitate understanding of the principles of the invention, it being understood that in actual practice more suitable power operatedmeans, as hydraulic cylinders, for example, may be employed to actuate the grip bits 26, the sleeve 3| and the arbor 35. This is particularly true as regards the arbor 35 since, as will appear later, the arbor in its forward position in the grip bits 26 may be employed to assist in the retraction of the drawing mandrel when shifting from pushing operation to full drawing operation.

I provide a drawing mandrel of novel and improved construction comprised of a rod 31 mounting an elongated plug 38 having the shape and dimension required to form the proper internal opening through the tube to be drawn. While the plug 38 may be integral with the rod 31 it is usually made removable from the rod by means of a screw threaded connection, not shown. Rigidly secured to the plug 38 is a tag 39 which may be of slightly smaller cross-sectional area than the opening through the tube to be drawn so that it may readily pass through the tube blank and the opening in the die l8 for engagement by the grip bits 26 or by the sleeve 32 at the start of a drawing operation. The outer end portion of the plug 38 is preferably formed of a separable sleeve 40 constructed of sintered tungsten carbide or other material having superior abrasion resistant characteristics. As will appear later the block portion represented by the section 40 will be subjected to the greatest wear and it is accordingly desirable that material of the indicated nature be employedfor this section. The portion 46 may be of cylindrical form and may be secured in position by a tapered stud bolt, not shown, integral with the tag 39 and screwed into the principal portion 38 of the mandrel.

Secured on the rod 31 is a collar 4| and interposed between the collar 4| and the plug 36 is a sleeve 42 and a coil spring 43 which normally biases the sleeve 42 into engagement with the plug 38. Sleeve 42 is, of course, slidably fitted on the shank 38 free to slide in the tube blank for a purpose to be hereinafter described.

Monaco- Therodt'l of the. drawing mandrelisconnected by means. of a universal jointv 44 with a forward end of a piston rod 45 which in turn extends through an. anchor block Atwh-ich extends upwardly. from the base 23. A collar 41' is secured in fixed-position on the rod 45 and the block 46 provided with a gate 41 whichwhen closed is. operative to prevent the passing through the. anchor 4'6. of. the. collar 4.1, in a direction towardthe die I8; Rod 45 is connected to a piston in a cylinder 48' which is slidable bodily insuite able ways 49 mounted on the base 23. and fluid pressure. is arranged to. be admitted to the rear end of: cylinder 48; through conduitxflq. to. ad- Vance the drawing mandrel, and to the. forward end of cylinder .48 through. conduit 51 to retract themandrel. It should be kept in. mind, at this point;- that such actuation of the drawing mandrel'. is: limited in extent by the length of stroke orthe. cylinder 48. Rigidly connected-with. the

outer housingof. the cylinder 48- is a. rod 52 connected with the piston in double-acting cylinder 5.3.which is also bodily slidable in the. ways 49. Fluid pressure is admitted tow the rear end. of cylinder 53 through conduit 54'to. move the cylinder 48 toward the die i8 and conduit 55' is provided to conduct fluid to the forward end of cylinder 53 to retract the cylinder 48. Rigidly connected. with the outer housing of the cylinder. 5.3"isa rod 56 connected with the piston in a double-acting cylinder 57 which is mounted in fixed relation on the base 23. A conduit 58 admits fluid under pressure to the. rear end of cylinder 51 While a. conduit 59 admits. fluid. to the forwardend, of cylinder 51.

To simplify the disclosure herein the various interlocking and sequentially operative electrical and hydraulic control circuits normally utilized for. the, actuation and control of. the various component parts of, the system including the grip bits 26,,the. arbor and the. cylinders I l, 2|, 48, 53, and 51 have been omitted and it is believed that the operation of the system from the following, fulldescription of a, complete cycle of operation will be readily understood.

At the start of a cycle of operation the parts are relatively positioned as shown in Figures 5 and, 50.. wherein the full retraction of both cylinders 48. and 53 frees the drawing mandrel entirely from the .pushing assembly even though the latter is also fully retracted and in this position the mandrel may be readily tilted upwardly about the joint 44. to enable a tube. blank to be slid over the outer free end of the mandrel. The

mandrelis now re-aligned with the axis of the die andfluid is admitted to cylinder 48 through conduit 50 and through conduit 54 to cylinder'53 to advance the tube blank (designated by referencenumeral- 69) into abutting relation with the die [8. and to advance the working part of the mandrel through the die, all as shown. in Figure 1a of the drawing. Gate 41 is open. At; this time the splitsleeve 32 is positioned between the gri bits 25 and after the carriage I0 is returned sufficiently to receive a substantial length of the projection 39 01. the mandrel in the sleeve 32 the lever 28.is operated to close the grip bits 25 onto the split sleeve 32 which in turn moves into tight clamping engagement with the projection 39. Fluid pressure is now admitted tothe conduits 25 and i6 and immediately the pushing grip bits 24 closeontothe blank 60 after which the grip block 20," begins tomove toward. the die, all as explained in the above, mentioned co-pending application Ser: No,. 49 0',06,0 and simultaneously therewithi the carriage "i0 will be moved outwardly to pull the. mandrel: fur-therthroughi the dieandl' initiate the drawing of the blank through the. die..- It should be observed; that due to. the-reduction. in the side wallthickness of theablank the linear speed of the blank as it leaves, the die.wi1l.. be greater than the. linear speed of the blanlsas it. enters the die and to prevent; sliding: of the mandrel in the blank either at or immediately following the die so as to reduce frictionalilosses. as: much as; possible, I. propose toproportion-the, flow ofv hydraulic fluid to the cylinders M and. 2|- in such manner as to compensate forthis speed variation. Such regulation may be readily accomplishedthrough the use of variabledis: placement hydraulic fluid pumps or through theuse. of flow control valves, as is well-understood inthe hydraulics art. Sincethe drawing mandrel moves along with the drawn portion-of the tube as distinguishedrfroman undrawn portion.

. of the tube,it will be obvious that themandrel shown in. Figures 2 and- 2a. At this time the flow of fluid to the conduits l8 and 2511s discontinuedabut if the tube has notbeen. extruded is'uie ficiently. to be clamped by the bits '26 the gri=p block 20 will be backed 01? and both cylinders l4 and 2!. will be again actuated in a forward direction toefiect further extrusion and drawing: ofv the tube. Upon sufiicient'tube.being'extruded the flow of fluid to conduit I6 is discontinued tointerrupt outward movement of the carriage-10. The-grips. 25- will now be opened by manipulation of the lever 28 and the sleeve 32 isv retraoted by manipulation of the lever 33. During theinitial combined extrusion and-drawing operation theforward movement. of the drawing mandrel was allowed by movement of the piston in the-cylinder 511, the cylinders 53v and 48. sliding bodily along the ways d9; After opening the bits. 26 fluid is admitted to: cylinder 5'11 through conduit-J 59 and. to cylinder .53. through conduit- 55 to retract the mandrel andv anchor rod liito position the collar 41" immediately behind; the gate A7: which is then closed. During such. retraction. the,- push-pointing mechanism which includes; the; grips 2.4-. may be utilized" tonclampand. hold the blankfitl. stationary. The dimensions of'the parts. are such that when the-collar M2 is: restrained-1 against outward movement by the. gate. ,41- the; wear-resistant portion. 49 of the drawing;-.man; duel. is positioned. in. operative relation: inthe;v die l8, as shown inFiguresBq and 4a.

Upon the mandrel portion Ali-beingpositioned and lockedin the diathe. grips Edwill closeouts the tube; with the arbor 35 positioned inside, the

tube and fluid is 'now admitted to the cond its:

At the same-time thetubemay beejectedgirem; between the. grips. 263. and.from the-iree-end t.

the arbor 35" by" operatinglever 33 to slide the" 7 sleeve 32 into the space between bits 26 formerly occupied by the outer end of the tube.

The desirability for the use of the sleeve 32 arises primarily from the desirability of making the block ll, grips 26 and associated roller races of reasonable length, for compactness, and since the wedge angle must be quite small to insure a heavy grip closing force. The range of movement of the bits 26 in a direction toward or away from each other is therefore necessarily quite limited and ordinarily it would not be possible for the same set of grip bits to adequately grasp both the tag 39 and the drawn tube which is formed on the working portion of the mandrel 38, 40. However, use of the sleeve 3|, 32 may be dispensed with if the tube product has very light gauge side walls and if the diameter of the tag 39 is only slightly smaller than the diameter of the working portion of the drawing mandrel.

As clearly shown in Figures 3a and 4a, the outer end of the tag 33 is provided with a centrally disposed conical indentation which is complementary to the conical free end of the arbor 35. Thus when it is desired to retract tag 39 from the grip bits 26, i. e., when the mandrel is retracted to position the portion 40 in the die I8, the arbor 35 may be advanced longitudinally by operation of the lever 36, or other means employed, to assist in retracting the mandrel and the interlocking interconnection between the free end of the arbor 35 and the tag 39 will guide the arbor in the performance of this function. Further, this interconnection will guide the entrance of the arbor into the end of the tube as evident from a comparison of Figures 2a and 3a of the drawing which illustrate successive steps in the cycle of operation of the apparatus. It should be observed, however, that the force exerted on the mandrel through the arbor 35 is merely supplementary to the principal mandrelretraction force exerted by the double-acting cylinders 53 and 51. The guiding of the arbor 35 into the end of the tube inherently results in the axial alignment of the grip bits 26 with the tube 60 so that any possibility of the end of the grip bits 26 colliding with the end of the tube is avoided. This feature is useful since the available clearance for entering the grip bits 26 over the tube is small.

It can be readily shown that the force required to extrude a tube blank through an annular die opening is much greater than is the force required to pull the tube blank through the same die opening. Consequently, even through the initial extrusion of the tube blank in the present invention is materially aided by a heavy pull on the mandrel, the grips 24 must yet exert a very heavy force on the tube since in any case the beneficial force which can be applied to the mandrel in pulling direction can never exceed the axial frictional force between the mandrel and the tube blank. If smooth-faced pushing grips were employed they would have to be of very large size and their mounting block would have to be of such weight and dimension as to be impractical. Therefore, practical considerations do not permit the use of smooth-faced grip bits in the push-pointing mechanism and accordingly such grip bits are provided with serrations. These serrations, however, are sufficiently fine so as not to mark the stock to an extent which cannot be removed in the single pass through the drawing die. The invention, therefore, provides an entirely practical method and apparatus whereby elongated metal objects, both bars and tubes, may

8 be readily reduced and drawn throughout their entire axial length and finished free of any grip marks or other deformation requiring scrapping of any portions of their lengths.

The above specifically described embodiment of my 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. Reference should therefore be had to the appended claims in determining the scope of the invention.

I claim:

1. Apparatus for drawing tubes comprising in combination a drawing die, a push-pointing device positioned ahead of said die and having means to grip the outer surface of a length of stock to extrude the same through said die, a draw carriage having gripping means positioned beyond said die, a mandrel having an elongated draw plug adjacent an end portion thereof and being reduced in diameter at said end portion, said gripping means on said carriage being operative to engage said reduced end portion of said mandrel and said extruded end portion of said stock length in succession, means to retract and mandrel, and means to anchor said mandrel in retracted position.

2. Tube drawing apparatus comprising in combination a drawing die, a push-pointing device die, a push-pointing device positioned ahead of said die and having means to grip the outer surface of a stock length to extrude an end portion of the same through said die, a draw carriage having gripping means positioned beyond said die, a drawing mandrel having an elongated sized portion adjacent an end portion thereof, said gripping means of said carriage being operative to engage said end portion to move said mandrel in said die simultaneously with the extrusion of said stock length by said push-pointing means, means to retract said mandrel, and means to anchor the same in retracted position, said gripping means on said carriage being also operative to engage the freestanding extruded end portion of said stock length.

3. A mandrel for tube drawing apparatus comprising in combination a shank, an elongated drawing plug secured to one end of said shank, a tag rigidly secured to and extending outwardly of the free end of said plug, a collar on said shank, a sleeve slidably mounted on said shank intermediate said collar and plug, and a coil spring mounted on said shank intermediate said collar and sleeve to normally maintain the latter in abutting relation with said plug.

4. A tube drawing apparatus having a drawing die, a push-pointer, a draw carriage, an elongated-plug type of mandrel having a tag projecting outwardly therefrom for gripping engagement by the draw carriage, means to retract said mandrel to a predetermined position relative to said die after movement of said mandrel through said die by engagement of said tag by said draw carriage, and releasable means to anchor said mandrel in said predetermined position.

5. Apparatus according to claim 4 further including a pair of cylinders mounted in tandem for retracting said mandrel to said pred t mined position, one of said cylinders being fixed with respect to said die and the other of said cyhnders being intermediate between the piston rod of said one of said cylinders and said 9 mandrel .and being slidably mounted for movement toward and away from said die.

6. Apparatus according to claim 5 further including a third slidably mounted cylinder interconnected between the piston rod of said second mentioned cylinder and said mandrel, the arrangement being such that actuation of said second and third cylinders in a forward direction is normally operative to move said mandrel forwardly through said die into position for engagement by said draw carriage while actuation of said first and second mentioned cylinders in a reverse direction is operative to retract said mandrel to said predetermined position while said third cylinder is fully actuated in a forward direction.

7. Tube drawing apparatus comprising an elongated drawing plug, a tag rigidly secured to and extending outwardly of one end of said plug and adapted to be engaged by a draw carriage, an anchor rod secured to and extending axially outward of the other end of said drawing plug, means engaging the rearward extremity of said anchor rod to limit the forward movement of said anchor rod and to retract said anchor rod to a predetermined rearward position, and releasable means engaging said rod to retain the same in said predetermined rearward position.

8. Apparatus according to claim 7 further in-' cluding a universal joint in said anchor rod whereby the forward portion of said anchor rod and said plug and tag may be tilted upwardly with respect to the axis of the rear portion of said anchor rod.

WALLACE E. KERR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 565,726 Rice Aug. 11, 1891 894,737 Higgins July 28, 1908 1,132,531 Webster Mar. 16, 1915 1,626,176 Atwood Apr. 26, 1927 2,331,953 Andrews Oct. 19, 1943 2,335,939 Hill Dec. '7, 1943 2,351,710 Sanders June 20, 1944 2,428,474 Snively Oct. 7, 1949 FOREIGN PATENTS Number Country Date Great Britain June 14, 1945

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