US2962164A

US2962164A - Metal extrusion

Info

Publication number: US2962164A
Application number: US859325A
Authority: US
Inventors: Albert W Scribner
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-12-14
Filing date: 1959-12-14
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29

Description

'Filed Deo. 14, 1959 METAL EXTRUSION 2 lSheets-Sheet l www* I NOV. 29, 1960 A W, SCRIBNER y 2,962,164

METAL EXTRUSION Filed Dec. 14, 1959 2 Sheets-Sheet 2 Patented Nov.A 29,

METAL EXTRUSION Albert W. Scribner, 89 Grennan Road, West Hartford 7, Conn.

Filed Dec. 14, 1959, Ser. No. 859,325

7 Claims. (Cl. 207-10) This invention relates to an improved method of die expressing metal and more particularly relates to a novel method for timing and locating the extrusion forces applied to a work billet.

This application is a continuation-in-part of my copending applications Serial Nos. 630,962 and 630,963, both tiled on December 27, 1956, and both entitled Metal Extrusion, and both now abandoned. t

In conventional types of metal extrusion operations,

such as that generally illustrated by U.S. Patent 2,335,590, some of the work material, namely that initially located radially outward from the limits of the die opening, must convergently ow toward the die opening before it can be extruded through said opening. Simultaneously the metal initially located nearer the billet axis flows in a direction which is more nearly parallel to the die axis before it passes through the die orifice. It will be noted that as the working ram advances that portion of the billet nearest the die axis ows through the die orice more readily than that portion of the billet located radially more remote from said axis. This prominent axial flow sharply curbs or restrains the convergent metal flow thereby causing the billet to be greatly distorted before it can be fully extruded. This distortion is accompanied by Va large amount of internal turbulent liow in the Vwork lmetal which in turn requires the application ofl excessively high working forces to eiect the'extrusion operation.

" One object of the instant invention is to provide a novel method for die expressing a work billet whereby the amount of turbulent metal ow may be substantially reduced.

Another object of the invention is to provide a method for sequentially controlling the convergent and axial iiow of the billet material during the extrusion operation.

Another object of the invention is to provide a method for sequentially die expressing a metal billet in two or more extrusion strokes whereby the total eifective working stroke for the overall extrusion operation may be increased to a length greater than the initial length of the work billet.

Another object of the invention is to provide a novel method for serially die expressing different longitudinal portions of the work billet using two or more consecutive extrusion strokes whereby the interference between the convergent and axial ow of the billet material is greatly reduced.

n Another object of the invention is to provide a novel method for more efficiently extruding a metal billet whereby the convergent Vmetal ow is produced by a forging action and the axial metal flow is produced by an extrusion action.

'f A further object of the invention is to provide a metal extrusion method wherein the energy required to die express a given size billet is much less than that required when using conventional methods. y

f Other objects and'many-of the-attendant advantages of this invention will be readily appreciated as the samey becomes better understood by reference to the follow-- ing detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like partsy throughout the figures thereof and wherein:

Figures 1, 2 and 3 are axial sectional views showing the sequential operation of the principal parts of -a metal` extrusion press which can be used to carry out the instant method.

Figures 4, 5, 6, 7 and 8 are axial sectional views of the principal parts of a metal extrusion press which canv be used to carry out two variations of the instant method.'-

Referring to Figure 1 there is shown a conventionally` supported container 1 which is adapted to receive and position a work billet. A tubular ram 2 is slidably mounted at the lower end 7 of said'container. inner end of ram 2 there is operatively secured an extrusion die 5 having'an orifice 6 formed therethrough. The cross sectional profile of ram 2 is preferably circular and has an effective area which is considerably less than that of the billet receiving chamber in the container 1. At the other end 8 of the container there is slidably mounted a ram 9 which has a work engaging' face 10 and a tubular'shank portion 11. The ram 9' is substantially coaxially disposed with respect to 'both' the container 1l and lthe ram 2.' Rams 2 and 9 may be power driven by any suitable means such as hydraulic' motors having controls for eiecting the respective sequential actuation of'the rams as hereinafter described.

In operation the rams 2 and 9 are withdrawn and a work billet is inserted in the work receiving chamber? of container 1. The rams are then advanced to theirinitial operative positions shown in Figure l wherein 'the respective operative faces of the rams engage the ends' of said work billet. Thereafter ram 9 is held xed'relative to container 1 while ram 2 is advanced through a' working stroke E1, as shown in Figure 2, to centrally pierce the en-d of the work billet and thereby indirectly die express the central longitudinal portion of the billet." The'cross sectional area of 'this centrallongitudinal bil-"-v let portion is greater than the crossl sectional area of the die orice 6. As the volume of the central portionv of the vbillet is thus being reduced the volumeof the substantially unworked outer longitudinal portion of thel billet remains substantially constant. Subsequently while container 1 remains stationary, ram 2 is withdrawn through a stroke E2 and ram 9 is simultaneously advanced through a working stroke E?, as shown in Figure' 3 to thereby die express the remaining tubular portion ofV the work billet. The relative speeds of the rams 2 and 9 during their respective working strokes E2 and E3 are such that the volumetricl displacement rate. ofrarn` 9 always exceeds that of ram 2'; i.e. the volume of the work billet is continually being reduced during said srtokes E2 and E3 thereby insuring a continuous die expressing of'the work material. The stroke E3 is-prefer ably started just prior to the termination of stroke E1' so that there is no interruption of metal il'ow through` the die oriiice 6 during the transition between the extrusion stages. Further, the amounts of the respective volumetric displacements of the rams 2 and 9 mayfbey controlled so that the actual extrusion of the workz metal continues at a substantially constant rate.

The cross sectional size of ram 2 may be adjustedso' that the maximum and average'forces required to executel the rst stage extrusion stroke El'most nearly correspondl to the maximum and average forces required'to execute? the second stage extrusion strokes lE5 and 1:33. In "this way the greatest operativejforce requirementsocclirrig'l at any time are reduced toa minimum value.' Theex On thev trusion strokes- E1 and E2, E3 may each be shortened whereby a plurality of alternate shortened strokes corresponding to strokes E1 and E2, E3 may be used to successively extrude several shorter radially inner and outer longitudinal portions of the billet to thereby. complete the die expressing of the billet.

By. applying extrusion forces-Ito the billet in two distinct extrusion stages as describedpabove. several.. advantages are obtained. First, the sequential displacement through die aperture 6 of the billet portions respectively located relativelynear` and relativelyl remote from the axis of said die aperture reduces the amount of billet` distortion normally associated with conventionalitypes of extrusion operations. internal turbulence in thework: materiaLand such-Will decrease the amount of: energyrequired: to extrude the billet. Secondly, it will' beinoted; that the total effective length of the two consecutive extrusion strokes E1 and E2, E3 is much greater than the initial'length of the billet. By using such a longer effective operative stroke the extrusion of the billet will be efliciently geared down so that the amount of' mechanical energy required to extrude the billet may be deliveredby the application of much smaller forces and as: a..result the structural elements ofthe press will be` subjected to much smaller working stresses whereby the overall construction of the press may be substantially lightened. Thus the initial, operating and maintenance costs for an extrusion press having a given required capacity may be greatly reduced.

It will be noted` that there. is-no sliding friction between the billet'metal and the inner` longitudinal walls of-the` container 1; the only relative movement between the billet metal andthe longitudinalsurfaces lofthe tools occurring over the relatively small outer surfaces of ram 2. Also anyiscale orv imperfections in the outer skin of the billet are. not extruded duringthe stroke E1. It will be apparent that the work billet: will assume the cylin drical shape of the work receiving chamber of the container 1 and will thus have a substantially uniform outer crosssectional profile during the working operations. With reference to the apparatus shown, the extrusion die 5 may be mounted on ram! 9' instead of on the ram 2, andV the relative movement between the rams 2 ande9 and/or the container 1- may be respectively etected` by the proper axial displacementV of said container relative to one or both of said rams. Also a conventionally supported and actuated mandrel maybe used with either of the two disclosed types of presses when it is desired to produce tubular extrusions from a` tubular or pierced work billet.

Two modifications of the instant method are respectively illustrated in Figuresv 46, and Figures 7 and 8. Referring to Figures 4-6 there is shown a conventionally supported container 15 having a cylindrical bore or chamber 16 which is adapted to receive and support a work billet. Slidably mounted. at the open end of container 15 are two coaxial and telescopically disposed tubular working rams 17 and 18. At the inner end of ram 18 there is operatively secured an extrusion die 19 having an orifice 20 formed therethrough. The

rams

17 and 18 may be respectively power operated by hydraulic motors having suitablecontrols for effecting the hereinafter described sequential operation.

In the extrusion operation illustrated in Figures 4-6 the

rams

17 and 18 are withdrawn and awork billet is inserted in the chamber 16 of the container. The rams are then advanced to their respective initial positions shown in Figure 4 wherein the inner ram faces engages the end of thebillet. The ram 17 is then held substantially iixed relative to the work billet whilethe ram 18 is advanced through a short extrusion stroke P as shownin Figure 5 to thereby pierce and reduce the volume of the central portion of billet. As'` will be apparent the cross sectiopalfareagof L this central billet portion will be. greater This will reduce ther amountof:

than that of the extrusion die orifice 20. During the extrusionstroke P the volume and` shape of the substantially unworked tubular peripheral portion of the billet material will remain substantially the same. The ram 17 is then advanced through a short forging stroke F1 while the ram 18 is simultaneously retracted through a short stroke F2 as shown in Figure 6 to thereby displace a part of the peripheral portion of said` billet material towards the billet axis and nearer` axialalignment with the die orilice. The rates and amounts of the respective volumetric displacements for the

rams

17 and 18 during the said strokes F1 and F2 aresubstantially equal and hence the volume of said` billet immediately before,.during and immediately after the execution ofstrokes F1 and F2 is substantially the same. As a result there will be substantially no die expressing of the work metal during these working strokes; rather the unextruded metal will be forged or reshaped so as to cause a radial outer por tion thereof to convergently ilow towards thebillet or die axispreparatory for asubsequent extrusion stroke. The extrusion stroke and `theforging stroke are then alternately repeated until the die expressing of the billet is completed. The ram-17 preferably commences its forging stroke F1 just prior to the completion of the extrusion stroke P so that there is no hesitation or interruption in the application of the-workingiforces; likewise the second extrusion stroke preferably commences just prior to the completion of the4 next preceding forging stroke; Here again` ther effective crossg; sectional areas of the: rams; 17 and V18` may beadjusted so that themaximumforcesi required to eifect the extrusion operations aresubstantially-thesameas the maximum forces required `to effect the` forging operations. In this way the largest force `required at any time during the working operations will be reduced to a minimum value.

By utilizing the` method described in connection with Figures 4-6 the amount of turbulent internal metal flow,A and hence the total. amount of mechanical energy re quiredto die express a given workY billet, is vreduced because a substantial part of the interference between the above noted convergent and axial metal flow patterns is` eliminated. The convergent ow of the work metal, instead` of tending; to choke the extrusion action as` in conventional extrusion operations,r here takes placedur-` ing a forging operation which is separate frornany sub-` stantial axial metal flow and which requires the appli-Y cation of working. forces that are much less thanrthe high extrusion forces normally required to produce the simultaneous and mutually interfering convergent and axial flow of the radially outer and inner portionsof the unextruded material. The reduced amount of mechanical energy necessary here to complete the extrusion operation is` a product of force times distanceand may be obtained by the applicationV of still further reduced maximum forces in that again. a relatively `long working stroke is` used, the combined lengthof the extrusion strokesY such, as` P being much greater than the initial length of the billet. Asbefore this permits apress of a desired capacity to have a far lighter construction and a much smaller power operating means. It will be noted in Figures 4-6 thatthe4 extrusion, forces exerted by ram 18 during stroke P are applied in a manner to directly localize the high extrusion pressures' in that region of the billet which is radially aswell as axially adjacent the die orice; thus the high unit extrusiony pressures are not dispersed and dissipated through the whole billet before they act on that portion of the billet material which is about to be dieV expressed.

Instead of starting the working operations with an ex? trusion stroke P as shown in Figure 5, the rams 17and 18 may be moved from their` respective initial positionsl to those shown in Figure 7 to thereby initially effect a forging operation wherein a peripheral portion ofthe billetis displaced towards the billet axis to` form a reduced axial extension.. Here the` ram 17 is. advanced` through a.

short stroke F3 while ram 18 is simultaneously retracted through a stroke F4. Again the rates of volumetric displacements of

rams

17 and 18 are substantially the same so that there is substantially no metal flow through the die orifice 20 during this billet reshaping operation. Thereafter ram 17 is held fixed relative to the unextruded billet material while ram 18 is advanced through a short extrusion stroke D as shown in Figure 8 to thereby die express a central portion of the billet material. At the end of stroke D the inner face of ram 18 may be slightly above or below the inner face of ram 17. These forging and extruding steps are alternately repeated until the die expressing of the work metal is completed.

In Figures 4-8 a displacement of the working

rams

17 and 18 relative to the container 15 is used to effectuate the billet working strokes, however it will be apparent that the container 15 may be properly moved relative to one or both of the same in order to effect one or more of the working strokes. In order to insure that no unfilled container space exists during the forging strokes F1 and F2 of Figure 6, for example, the rate and amount of volumetric displacement for the stroke F1 may be made slightly greater than that for stroke F2 whereby a very slight amount of extrusion of the billet will occur during the forging operations. The die 19 may be operatively mounted in the upper end wall of the container 1; and the

rams

17 and 18 may be mounted at opposite ends of the container with the die operatively secured to either of said rams.

While several embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that numerous variations and modifications may be made in the particular construction without departing from the underlying principles of the invention. It is therefore desired, by the following claims, to include Within the scope of the invention all such variations and modifications whereby substantially the results of the invention may be obtained by the use of substantially the same or equivalent means.

The invention claimed is:

l. A method of die expressing -a work billet of solid metal which has a substantially uniform cross section and which is operatively confined adjacent an extrusion die orifice; comprising the steps of die expressing a radially central portion of said billet through said orifice by longitudinally and centrally piercing one end of said billet, the cross sectional area of said central portion of said billet being greater than that of said orifice, and die expressing substantially the remaining radially outer tubular longitudinal portion of said billet by applying an extrusion force to the unextruded portion of said billet.

2. The method defined by claim l wherein the volume of the work material in said outer tubular billet portion remains substantially constant during the first mentioned die expressing step.

3. A method of die expressing a work billet of solid metal which has a substantially uniform cross section and which is operatively confined adjacent an extrusion die orifice; comprising the successive steps of centrally piercing said billet and indirectly die expressing substantially the central portion of said billet through said orifice by applying an extrusion force to just the center part of the billet end cross section, and die expressing substantially the remaining tubular portion of said billet by applying an extrusion force to the unextruded outer portion of said billet.

4. The method defined by claim 3 wherein the die expressing strokes are each shortened in length and are alternately repeated to successively extrude several shorter inner and outer portions of said work billet.

5. A method of die expressing a metal billet; comprising the steps of operatively confining the billet adjacent lan extrusion die orifice, axially piercing one end of said billet to thereby die express a central portion of said billet, forging the unextruded billet material while keeping the volume thereof substantially constant so as to increase the amount of work material located near axial alignment with said die orifice, and axially piercing the reshaped unextruded material to thereby die express a central portion of the reshaped work material.

6. A method of die expressing a work billet; comprising the steps of operatively confining the billet adjacent an extrusion die orifice, reducing the volume of said work billet to thereby die express a portion of the work billet material through said orifice, reshaping the unextruded work material while keeping the volume thereof substantially constant so as to increase the amount of unextruded work material which is located near axial alignment with said extrusion die orifice, and reducing the volume of the reshaped work material to thereby extrude another portion of the work material through said die orifice.

7. The method defined by claim 6 wherein the reshaping step produces a reduced axial extension on the unextruded work material.

References Cited in the file of this patent UNITED STATES PATENTS 74,755 Farrell Feb. 25, 1868 2,230,840 Jongedyk Feb. 4, 1941 2,920,760 Genders Jan. 12, 1960