US2638213A - Extrusion die for tubing - Google Patents

Description

y 1953 D; H. CLARK EXTRUSION DIE FOR TUBING Filed Oct. 14, 1948 Patented May 12, 1953 UNITED STATES PATENT OFFICE" 2,638,213 EXTRUSION DIE FOR TUBING Dalton H. Clark, Pontiac, Mich.

Application October 14, 1948, Serial No. 54,449

This invention relates to dies and, in particular, to extrusion dies for producing metal tubing.

One object of this invention is to provide a tubing extrusion die which is well adapted for the extrusion of brass and copper tubing, and enabling the removal of the billet butt and its replacement by a fresh billet without substantial interruption in the extrusion procedure.

Another object is to provide a tubing extrusion die which eliminates the necessity for the use of a floating mandril hitherto used in extruding brass and copper tubing, and which pro vides a smooth and uninterrupted flow of the metal from the billet to the extrusion ring.

Another object is to provide a tubing extrusion die having multiple portholes converging into an annular mixing chamber around an integral core or mandril, the latterin turn opening into the annular opening between the extrusion ring and the mandril.

v Another object is to provide a tubing extrusion die of the foregoing character wherein the central portion of the die on its entrance side is rounded so as to direct the metal from the billet into the multiple converging portholes which surround the central portion of the die.

In the drawings:

Figure 1 is a central vertical section through a brass tubing extrusion die as installed in an extrusion press, and with a metal billetengaging the entrance side of the die prior to the commencement of extrusion along the line l-l in Figure 3; A

Figure 2 is a cross-section along the line 2-2 in Figure 1, showing the entrance sideoi the extrusion die in front elevation;

' Figure 3 is a cross-section along the line 3-3 in Figure 1, showing the exit side of the extrusion die in rear elevation;

Figure 4 is a fragmentary longitudinal section along the line 4-4 in Figure 2;

Figure 5 is a longitudinal section along the line 5-5 in Figure 3; and

Figure 6 is a longitudinal section similar to Figure 1, but showing the apparatus in a later stage of operation wherein a portion of tubing has been extruded.

In the extrusion of brass or copper tubing, it has hitherto been found difiicult to extrude the brass or copper without the employment of a floating mandril which projects outward into the brass or copper billet which furnishes the material for the tubing. These billets are heated der l2 rests against an abutment member which, in turn, rests against the die housing 15'' 3 Claims. (Cl. 207-17) has been pushed as far as practical into the die, it cannot be removed by pulling it rearwardly. Accordingly, in such extrusion operations as hitherto conducted, the butt remaining from the billet has had to be removed from the die before the operator could start extrusion with a new billet.

The extrusion die of the present invention eliminates the floating mandril and instead employs a mandril which is, solidly built into the die and does not project from it. The mandril is surrounded by converging portholes through which the hot metal is forced by the extrusion press. The butt remaining from the billet is capable of removal merely by pulling it out after the maximum amount of material has been exders or abutments which would impede the flow of the metal. As a consequence, metal tubing is quickly and efliciently extruded and tubing ihav-,

ing unusually thin walls can, be extruded and extrusion can be almost continuously carried out, with but slight halts necessitated by the:

withdrawal of the butt and the insertion of a new billet. The die, by reason of its novel con- Struction, contains a minimum amount ,of hot metal which flows freely through the portholes into the mixingchamber and thence through the annular extrusion opening between the :extrusion ring and the mandril.

Referring to the drawings in detail, Figure shows a portion of an extrusion press, generally designated ID, in which is inserted a tubing extrusion die, generally designated ll, according to the present invention, by which tubing is ex-' truded from brass or copper billets B. Theex trusion press II] is of conventional design, its details forming no part of the present invention, and any suitable conventional extrusion press may be used. For the purposesofl the present. disclosure, it is shown as including a cylinder I2 having a cylinder bore '14 in which the metal billet B is inserted and engaged by a plunger or The forward end of the cylinram (not shown).

A new billet, suitably heated, can

connected to the bed (not shown) of the extrusion press. The die housing is provided with a counterbore l6 terminating in an annularly shouldered rear or bottom surface i'i having a central opening or bore I8 through which the completed tubing emerges. The abutment member I3 is also provided with an opening or bore H] of slightly smaller diameter than the bore 16, so as to retain the die I! in position.

The die ll consists generally of a die body 29 and an extrusion ring 2! inserted in a counterbore or recess 22 in the rearward end of the body and having a bottom or rear surface 23. The body 20 is surrounded by an annular groove 23 which receives the abutment member it (Figure l 1) and is held in position by the latter; The die body 20 is of generally cylindrical shape with a slightly recessed front surface 25 and a flat rear surface 26, the latter abutting the annular shoulder H. In the center of the front surface 25 is a slightly rounded protuberance 21 surrounded by a dished portion 28 in which are located inwardly and rearwardly converging porth-ole or metal passageways 29 having flared entrance portions 30.

. The portholes 29. are arranged on opposite sides of a central integral core 3| forming a mandril and having an extension 32 extending rearwardly (Figures 1, 4 and 5). The mandril portion 32 is surrounded by a neck portion 33 which is of slightly reduced diameter and which separates it fromrthe main portion of the core 3| and which forms. part of the wall of an annular mixing chamber 34 into which the portholes 29 converge (Figures 1 and 4). The portholes 29 are separated from one another by web portions 35 and have the rearward outlets to opening into the mixing chamber 34. I

Beyond the mixing chamber 34 the mandril or core extension 32 is provided with an approximatelycylindrical outer surface 31 which spaced radially from the corresponding surface of the bore 38 in the extrusion ring 2| so as to form an annular extrusion passageway 39 therebetween. The extreme end t!) of the mandril or core extension 32 is slightly rounded or bevelled and the, corresponding end portion 4| of the extrusion ring bore 38 is flared outwardly. The? central portion 42 of the extrusion ring surface; or bore 38 is cylindrical and the inner por- I tion 43 approximately conical, converging toward the, cylindrical portion 42 in a continuation of the converging direction of the portholes or metal passages 29. The front or inner edge. 44. of the bore 38 in the extrusion ring 2| is rounded to prevent. the formation of a shearing edge and to enhance the flow of the metal from themixing' chamber 34 into the passageway 39.

I n orde'r to properly locate the extrusion ring 2| in-its recess or counterbore 22, the ring 2| is provided with a hole 45 (Figure 5) with which is aligned a corresponding hole 45a in the die body 20. The. hole 45 receives a dowel pin or locating pin 46 which enters the locating hole 45a when the ring 2| is properly inserted in its recess 22 in the die body 20. The mandril portion 32 of the ore body 20. and the extrusion ring 2| thus form male and female dies respectively, between which the metal is extruded from the billet B to form atube'T (Figure 6.).

Operation the operation of the invention a suitably heated metal billet B is placed in the bore 14 oi the cylinder l2; and pressure applied by the usual plunger (not shown) to force the inner end of the billet B against the forward end 25 of the die body 2t. The metal first encounters the rounded protuberance 21 which projects like an island from the center of the dished portion 28. The protuberance 2? and the flared entrances 3i assist in diverting and facilitating the flow of the metal into the converging portholes 29 and thence into the mixing chamber 34. The streams of metal flowing through the portholes 29 reunite in the mixing chamber 34 where they are caused to intermingle by the slight back pressure set up by the fact that the annular extrusion passageway 39 is somewhat narrower than the mixing chamber 34 (Figures 1 and 5). The metal, thus thoroughly mixed and intermingled, flows out through the extrusion passageway 39 and forms the tube T which is then handled in the usual way.

When as much of thebillet B has been extrud ed as is conveniently practical and it isneces sary to change billets, the removal of the butt of the billet B is easily accomplished merely by grasping it and forcibly pulling it backward away from the extrusion die or conversely, by pulling the die from the billet. When thisis done; the stems 5 (Figure 6) remaining in the portholes 29 are ruptured without harm, severing the butt from the extruded tube T. It is then merely necessary to withdraw the butt of the. billet B and insert a new heated billet B, apply pressure thereto by means of the plunger or ram of the extrusion press I!) and continue operations with very little interruption. This procedure, which ismade possible by the construction of the extrusion die I of the present invention avoids the time consuming procedure previously necessary in removing the butt where a floatingmandrilwas used in connection with the extrusion die in extruding brass or copper tubing. v v

In the present invention, the mandril extension 32 and the core 3| are integral with the die body 29, hence no injury to them can occur by the withdrawal of the butt, whereas the forcible c withdrawal of the billet butt from prior dies emedges.

The extrusion dieof the present invention, pro vides a mixing chamber 34 which tends to part a circular motion to the streams of metal thus creating an improved. inter-mingling and bond between them- This circular motion is enhanced by the contour of the, outlets 36 of the portholes 29. The mandril portion 32 and extrusion ring 2| enhance this circular motion. The number of portholes may be increased or decreased, depending upon the. size and shape of the tube desired. The converging arrangement of the portholes 29 tends to give greater strength to the core 3|, including. the mandril portion 32 and also facilitates pulling away the billet butt When it is necessary to change billets. The flared. portion 4| at the outlet of the extrusion ring 2|- enables the metal to flow over it rather than be sheared as in the action with certain types of' This shearing action" The. portholes 29 are preferably equally spaced:

around the core. or mandril' 3| and accurately drilled to provide equal pressure on all sides of the mandril. The size of the portholes is determined by the size of tube and wall thickness required, and also by the necessity of providing sufficient support for the mandril. The front face 25 of the die body 20 is concave or dished as at 28 to permit the front end of the billet B to fit more snugly so as to prevent spreading of the butt. The formation of the mandril or core 32 is an integral part of the die body 20, together with the relatively small diameters of the portholes 29 and their converging arrangement permits the billet butt to be pulled off cleanly and a new billet to be inserted immediately without substantial interruption.

The extrusion die I I of the present invention is adapted to be used in almost any type of extrusion press which is available on the market. The configuration of the extrusion ring bore 38 and mandril extension 32 may be varied to suitably shape the passageways 3:! so that tubing of any desired cross-sectional shape may be extruded; for example, tubing of round, oval, square, hexagonal or octagonal cross-section. It will be understood that the extrusion of copper requires a higher temperature for the billet than brass. Accordingly, a grade of steel or other suitable metal which will withstand the higher temperature must be used for the parts of the die which come into contact with the hot copper. Such steel capable of withstanding a higher temperature required for extruding the copper tubing is available on the market.

What I claim is:

l. A die for extruding brass or copper tubing comprising a die body having metal flow passageways converging inwardly and rearwardly from the forward portion thereof, a mixing chamber interconnecting said passageways, and an approximately annular extrusion opening communicating with said mixing chamber, the major portion of the forward face of said die body having a raised peripheral portion projecting forwardly therefrom and a concave surface disposed inwardly of said peripheral portion and depressed below the level thereof, the entrances to said flow passageways being located in said concave surface.

2. A die for extruding brass or copper tubing comprising a die body having metal flow passageways converging inwardly and rearwardly from the forward portion thereof, a mixing chamber interconnecting said passageways, and an approximately annular extrusion opening communicating with said mixing chamber, the major portion of the forward face of said die body having a concave surface, the central part only of said concave surface having an approximately central protuberance therein and the entrances to said flow passageways being located in said concave surface laterally outward of said protuberance.

3. A die for extruding brass or copper tubing comprising a die body having metal flow pas sageways converging inwardly and rearwardly from the forward portion thereof, a mixing chamber interconnecting said passageways, and

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,341,749 Webb Feb. 15, 1944 2,368,355 Guiney Jan. 30, 19%5 FOREIGN PATENTS Number Country Date 99,405 Germany Oct. 11, 1898 330,049 Great Britain June 5, 1930 375,279 Great Britain Dec. 19, 1930

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