US2755925A

US2755925A - Extrusion of metals

Info

Publication number: US2755925A
Application number: US337394A
Authority: US
Inventors: Boccon-Gibod Raymond; Chevigny Raymond
Original assignee: Pechiney SA
Current assignee: Pechiney SA
Priority date: 1952-02-26
Filing date: 1953-02-17
Publication date: 1956-07-24
Anticipated expiration: 1973-07-24

Description

EXTRUS ION OF METALS Pics. '5

Filed Feb. 17, 1953 Pic-3.1

Fie.'2

m E W E m fi m A3 d & g m 6 H B 3 mm 4 3 W% r Jul 1 f I nd Raymond Chevigng BY A ATTORNEY 2,755,925 EXTRUSION 0F METALS Application February 17, 1953, Serial No. 337,394

Claims priority, application France February 26, 1952 9 Claims. (Cl. 207-9) The present invention relates to the extrusion of metallic materials. It is concerned more particularly With those metals which are highly susceptible to alteration at the temperature of extrusion, or which react with the materials commonly used in the construction of the extrusion apparatus.

In the extrusion of such metals, it is more often than not necessary to heat the billet (slug) to be extruded and, in many cases, it is necessary to avoid on the one hand the oxidation of the metal and, on the other hand, its contact with the apparatus, usually of ordinary or special steel, because of the alloying that may take place at the temperature of extrusion. Moreover, it is not always possible to reheat the die to the required temperature, and this may cause cracks or even interruption of the extrusion.

Up until now, it has been attempted to solve this problem either by means of a rotary (turret) furnace operating with a neutral atmosphere, which permits direct introduction of the billet into the container of the press, or by jacketing the billet with a sleeve which is extruded together with the metal. However, in the case of both these solutions, there is always contact between the metal to be extruded and materials which may react therewith.

The improvement, due to the present invention, enables the extrusion to be carried out while guarding the extruded material from contact with both the atmosphere and the Walls of the apparatus used.

The invention primarily comprises a process which consists in enclosing the billet within a protective shell or sleeve before it is placed in the furnace where it is heated to the extrusion temperature, and in then introducing the billet-while still enclosed in said sleeveinto an extruding press and progressively pushing it out from the sleeve through the die, by means of the same pressure which is used to effect the extrusion, the billet being pushed out from the sleeve as the extrusion proceeds.

According to a preferred embodiment of this process, one or more parts of the extrusion apparatus, such as the dummy block, die, die block, etc., are enclosed together with the billet in said protective sleeve.

According to a particular feature of the invention, sulficient clearance (play) exists between the billet and its sleeve, so that it is possible to keep them apart by a layer of a solid, liquid, or gaseous substance.

According to another feature of the new process, the extruded hot material, as it leaves the die, continues to be protected-until it has been cooled-by a second shell which may contain (or be traversed by) a suitable gas, liquid or powder.

According to another feature of the invention, it can be so arranged that the withdrawal of the sleeve, following the extrusion, is effected by passing the same from the container into said second shell through a closable aperture.

The invention also relates to an apparatus for carrying out the described process.

This apparatus essentially comprises a sleeve or jacket which surrounds the billet laterally, and removable stops States atent (plugs) placed at the ends of the latter. These parts are made of materials which are appropriate for the mechani-- cal stresses involved, the temperature, the nature of theterials alternately; for example,.layers of insulating, re-

fractory, fluid or other material can be superposed upon metallic walls. 1

In a particularly practical embodiment, the said plugs or stops are constituted of the die itself and its support, at one end of the billet while, at the other end, the dummy block (bearing plate) itself acts as a plug.

The assembly thus formed of the billet, its sleeve, the

(lie, the die support and the dummy block, is adapted for use with extruding presses of being placed in the container thereof.

However, an improved apparatus, according to the present invention, preferably comprises:

Circulation of an inert of suitable powder or liquid within protects the extruded articles against its block, receptacle for the extruded articles. truding press is used, vide at the bottom of the receptacle, a spring, acting as shock-absorber for the falling sleeve as it leaves the container of the press afterthe extrusion.

The invention is illustrated by the following description of two non-limitative embodiments of the new process and apparatus.

Figure 1 is a vertical section through an apparatus for the extrusion of a metal susceptible to alteration in air.

Figure 2 is likewise a vertical section of a billet with its protecting sleeve placed in the container of an extrusion Dress.

Figure 3, similar to Figure 2, illustrates the particular case of a protective shell having double walls.

Reference numeral 1 designates a cylindrical sleeve or shell of a material sufiiciently resistant at the operating temperatures to support the weight of the billet. Its diameter and height are slightly greater than those of the billet.

2 indicates a die block, for example, of stainless steel, removably fastened to the bottom of the sleeve.

device and the When a vertical exto additionally prosuitable material interposed between them. The billet 4 itself rests on the die 3; it is completely surrounded by the sleeve 1. The dummy block 5 rests on the billet 4.

In Figure 3, which shows a variant, the walls 11 and The apparatus is used in the following manner:

Sufficient play is provided between billet 4 and sleeve 1 to avoid contact between these two parts during heating.

This assembly, disposed vertically, is heated up to the desired temperature of extrusion in a furnace containknown types, the assembly ing a neutral atmosphere, and is then transferred into the container 6 of the press (Figure 1). During this transfer, which is made in open air, the dummy block 5 protects the metal from oxidation.

h p tl; h r i of u c the press s ac uated and'the rnetahalone is extruded through the die. It is received in the tube 8 placed at the base of the press and whielixis filled with a gas which is neutral with respect to the metal;

' 'Bymeans of hand levers 14, the plugs 9 are operated to completely open the passage from 4; towards 8; the sleeve '1 ,"the die '3, its block 2, the dummy block 5 and the remainder of the non-extruded metal (the extruded part thereof extends downward. as the extruded rod) then fall into the upper enlarged part of tube 8, on the spring 10." i

Tube 3 is now, hermetically closed and is removed from the press so that itcan bereplaced with another similar tubeand' another billet extruded' immediately. In the meantime, the extruded metal cools in the narrower portion of the tub e; its cooling can be hastenedby circulating water in the doublewalledtubegthe extruded metal is withdrawn when it has attained a temperature at which oxidation is be feared, The die block 2 is then removed from he sleeve, and what remains in the sleeve is pushed out. Thus the die, the sleeve and the dummy block are recovered and can be reused for another operation, eventually, after correcting the dimension of the outer diameter of the sleeve.

By operating in this manner, the'die is heated to the same temperature asthe metal, which facilitates the extrusion and avoids excessive heating of the container of no longer to the'pr ess whenjthe extrusion is carried out at very high mp ra ur s:

11'1" the'event it is not possible to find a metal for the prote ive sleeve which does not react with the material to t ud n p o ement. according to he nvention,'consistsjin coating the internalfwall of the sleeve with a, thin 'sheet of a metal which does not react with e a e ial, to be trudr ...or n pray ng a pro e metal or other material on said internalwall or else, in l n t e P??? mr isedbetweea h il e the es a ith? nwdetedfln pduet (for, xample, alum n graphite, etc.) which does not react with thematerial of he illet; pl tas betwe n, hebi e an v h le i v d ur ng t e! extrusi n ,ope a iq Simibrlwt'a' matsri lwhich does no a t with t metal... s t l siadisinot va lable for' he con tr ti n of'the' die and the dummy block, the working surfaces of hes arts ma ililrewise e ntoteet dbv sp ay n he eon a suitable s ance whi h pre ludes any nt t u ng h x rusion, operat on.-

t s' w lj .d rstood,that he p o e nd apparatus des ibed are. alsgapplicablef when the. billet is heated with n the press. itself andnot in a separate furnace. Moreoyer in that event, one or more of the aforementioned protective layers of thesleeve can serve for the reception o f the heating means.

ltfis also understood that the present invention can, a f0rtior i, be 'appliedtothe extrusionof materialssusceptible to,alteration which do not require heating.

By way ofiexample' mentionismade of theiextrusion carried out in accordance with the present invention. The difliculties encountered with this metal are: extreme susceptibility to oxidation. and rapid reaction with any ferrous alloys at temperatures from 800' upwards (while the metal must be extruded at about 950 C. to 1000 C.) with formation of an undesirable liquid eutectic. A billet having a diameter of 92 mm, and a, height of 200 mr'nfiis introduced into a cylindrical sleeve of stainless steel, having an inner diameter of 98 mm. and aheight of 33(1. The outer diameter of the sleeve (107 mm.) is such that this p r ssufiis e t meehani a ustrens IQQO: C, and can slide with but a slight clearance, within the container otthe press. Thev billet rests on a die of tungsten carbide, itself supported on a die block. The sleeve is capped wih a dummy block of tungsten carbide. The inner walls of the sleeve are coated with sprayed graphite in order to avoid any reaction between the uranium and the sleeve. An even better protection is obtained by filling the space between the sleeve and the billet with graphite powder.

It has been observed, that due to a slow action of the uranium on the tungsten carbide, the dies and dummy block deteriorate. Wear of these parts is completely avoided by spraying a layer of graphite on their working surfaces. The assembly is heated in an argon atmosphere at 950 .1000. C. and. then introduced into the container of the press, heated at 500 (1., below which is placed the receiving tube through which argon is passed. As shown in Figure l, the. argon is introduced at the bottom of the tube (in the direction of the arrow) and e capes hrough. he upper. part. of the app r While nveloping the. assembly of. devices. supporting the billet and filling the spases existing, before. andafter extrusion, between the sleeve and, the. container. Inthis way, the argon supplied.undelpressure precludes entry of air from any direction. After the extrusion, the plugs are drawn out and the, assembly drops into. the receiver tube, the walls ofwhich arecooled with-water and which is closed with a tightrcover, Following. cooling, the assembly is withdrawn 'fromthereceptacle and thedummy block, die and die block. arerecovered.

We. laim:

1. Process for extruding metallic substances susceptible to: detrimental'alteration at the temperature of extrusion by contact withthe atmosphere and the metallic workingpartsofanrextrusion press, comprisingthe steps of: fasteningga;dieblocltlinside the lower end of. a protective sleeve; placing an extrusion die, a billet to be extruded, and'adummy block, in the, order named, on top of'said dieblock inside said sleeve, at least the inner surface of saidrsleeve, and the working surface of die being 'nonrrea ctiveto theIrnate-rial of the billet at the temperature, of.- extrusion, inserting, the aforementioned sleeveas mblv illsideihecontainer ofan extrusion press, and on top. of. a, support. providedwith a controllable aperture; applying. pressure to, the billet to force the same from its sleeve and simultaneously extrude it through the dieto, ohtainan extruded, articleof the desired shape; and uponc 'rnpletion. of;theextrusion;operation, increasingthe openingot, saidraperture, to-permit-passage of the sleeve assemblvitherethro gh.

2 An extrusion press comprising in combination: a container; aprotective .sleevefor the billet to, be extruded placed insidesaid container; a die block removably fas tenedto the lower end "of. said sleeveyan extrusion die disposed inside said, sleeve andsupported on said die block; a dummy blockforming a closure for saidlsleeve at the, upper endthereof; asupport comprising Va,controllable'aperture; and means forincreasing said aperture to permitpassage. therethrough of all the partssupported thereon.

3. An apparatusaccordingto claim 2,. characterized in thatithe s1eeveis formed of concentric walls of difierent materials."

4. A.removab,1e assembly. for use in the container, of an extrusion,preselcorntrrising in, combination: a sleeve; a die blockremovahly seeuredtothe lower portion of said sleeve; and auiextrusiomdie; arbillet to beextruded, and a dummy block placed inside said sleeve, in the order n m d, outcast aid die block;

5 An ex' io presscomprising inc mbination a container; .a,p rotective; sleeve for thebillet .to be extruded.

placed,insideeaidiconta neu; a dieblockremovably fastened to the lower end of said sleeve; disposed; inside; said;sleeve:.and.;supported on said die block; a dummy block forming aclosure for-said sleeveat the upper'e nd thereofya supportfor said die block comprising a controllahle aperture; means for increasing for said die block.

an extrusion die.

said aperture to permit passage therethrough of all the parts supported thereon; a receiver for the reception of the extruded article, the upper portion of said receiver being provided with an enlarged section for the reception of said sleeve.

6. An apparatus according to claim 5, wherein shock absorbing means are placed inside the portion of the receiver beneath the enlarged section.

7. Process for extruding metallic substances susceptible to detrimental alteration at the temperature of extrusion by contact with the atmosphere and the metallic working parts of an extrusion press, comprising the steps of: fastening a die block inside the lower end of a protective sleeve; placing an extrusion die, a billet to be extruded, and a dummy block, in the order named, on top of said die block inside said sleeve, at least the inner surface of said sleeve and the working surface of the die being nonreactive to the material of the billet at the temperature of extrusion; inserting the aforementioned sleeve assembly inside the container of an extrusion press, applying pressure to the billet to force the same from its sleeve and simultaneously extrude it through the die to obtain an extruded article of the desired shape.

8. Process according to claim 5, characterized in that the billet is placed in the sleeve so as to leave a space therebetween, and in that the non-reactive inner surface of the sleeve is obtained by placing a layer of inert material on said inner surface.

References Cited in the file of this patent UNITED STATES PATENTS 567,410 Potter Sept. 8, 1896 819,261 Wood May 1, 1906 1,111,698 Liebmann Sept. 22, 1914 1,653,367 Marden et a1. Dec. 20, 1927 2,075,622 Nehlson Mar. 30, 1937 2,123,416 Graham July 12, 1938 2,188,076 Dinzl c Jan. 23, 1940 2,283,791 Clark May 19, 1942 2,290,734 Brassert July 21, 1942 2,594,009 Gibian Apr. 22, 1952 FOREIGN PATENTS 657,959 Great Britain Oct. 3, 1951 683,785 France June 17, 1930 789,411 France Oct. 29, 1935

Claims

1. PROCESS FOR EXTENDING METALLIC SUBSTANCES SUSCEPTIBLE TO DETRIMENTAL ALTERATION AT THE TEMPERATURE OF EXTRUSION BY CONTACT WITH THE ATMOSPHERE AND THE METALLIC WORKING PARTS OF AN EXTRUSION PRESS, CONPRISING THE STEPS OF: FASTENING A DIE BLOCK INSIDE THE LOWER END OF A PROTECTIVE SLEEVE; PLACING AN EXTRUSION DIE, A BILLET TO BE EXTRUDED, AND A DUMMY BLOCK, IN THE ORDER NAMED, ON TOP OF SAID DIE BLOCK INSIDE SAID SLEEVE, AT LEAST THE INNER SURFACE OF SAID SLEEVE AND THE WORKING SURFACE OF DIE BEING NON-REACTIVE TO THE MATERIAL OF THE BILLET AT THE TEMPERATURE OF EXTRUSION; INSERTING THE AFOREMENTIONED SLEEVE ASSEMBLY INSIDE THE CONTAINER OF AN EXTRUSION PRESS, AND ON TOP OF A SUPPORT PROVIDED WITH A CONTROLLABLE APERTURE; APPLYING PRESSURE TO THE BILLET TO FORCE THE SAME FROM ITS SLEEVE AND SIMULTAUEOUSLY EXTRUDE IT THROUGH THE DIE TO OBTAIN AN EXTRACT ARTICLE OF THE DESIRED SHAPE; AND UPON COMPLETION OF THE EXTRUSION OPERATION, INCREASING THE OPENING OF SAID APERTURE, TO PERMIT PASSING OF THE SLEEVE ASSEMBLY THERETHROUGH.

5. AN EXTRUSION PRESS COMPRISING IN COMBINATION A CONTAINER; A PROTECTIVE SLEEVE FOR THE BILLET TO BE EXTRUDED PLACED INSIDE SAID CONTAINER; A DIE BLOCK REMOVABLY FASTENED TO THE LOWER END OF SAID SLEEVE; AN EXTRUSION DIE DISPOSED INSIDE SAID SLEEVE AND SUPPORTED ON SAID DIE BLOCK; A DUMMY BLOCK FORMING A CLOSURE FOR SAID SLEEVE AT THE UPPER END THEREOF; A SUPPORT FOR SAID DIE BLOCK COMPRISING A CONTROLLABLE APERTURE; MEANS FOR INCREASING SAID APERTURE TO PERMIT PASSING THERETHROUGH OF ALL THE PARTS SUPPORTED THEREON; A RECEIVER FOR THE RECEPTION OF THE EXTRUDED ARTICLE, THE UPPER PORTION OF SAID RECEIVER BEING PROVIDED WITH AN ENLARGED SECTION FOR THE RECEPTION OF SAID SLEEVE.