US2283791A - Extrusion machine cylinder or container - Google Patents

Description

1 j P. L. CLARK- EXTRUSION MACHINE CYLINDER 0R CONTAINER Y May 19, 1942.

Filed July 20, 1940 2 Sheets-Sheet 1 v INVENTCQR xv ATTORNEYS y 1942- \P. L.- CLARK 2,283,79i

EXTRUSION MACHINE CYLINDER OR CONTAINER Filed July 20, 1940 2 Sheets-Sheet 2 ATTORNEYS Patented May 19, 1942 EXTRUSION MACHINE CYLINDER on comma Percy L. Clark, Fail-field, Conn., assignor to I Bridgeport Brass Company, Bridgeport, Conn., a corporation of Connecticut Application July 20, 1940, Serial No. 346,474

3 Claims.

This invention relates to extrusion machine cylinders or containers. An extrusion machine consists essentially of a container, 9. ramand a die. A hot billet of suitable metal is placed in the container and the ram exerts pressure thereon to extrude the metal through the die.

Heretofore, extrusion machine containers have consisted of a tubular body containing a. continuous tubular steel liner. Such liner is subject to complex stresses and must be made oi material sumciently hard and tough to withstand the abrasive wear and tensile stresses brought about by frictional contact of the hot billet with the interior of the liner and still must not be of sufficient brittleness to permit longitudinal or circumferential breakage of the liner. Also, it must be composed of metal which will withstand sudden variations in temperature and pressure and'sti'll maintain the required physical strength at the temperatures under which the extrusion takes place.

As extrusion has been applied to alloys of increasingly higher elastic limits, many of which require the use of higher temperatures than formerly used, it has become necessary to find steel which combined to a greater extent some or all of the above-mentioned qualities. The addition of elements such as tungsten, cobalt, molybdenum, chromium or alloys having similar heat resisting characteristics to steel melts for the purpose of resisting the stresses at higher temperature, increases the dimculty of maintaining ductility and preventing breakage when heat treated, distortion and excessive abrasive wear.

A steel satisfying all the above requirements can be obtained only at considerable difficulty and expense. I

An object of this invention is an extrusion container structure provided with a liner in which circumferential tensile stresses are substantially eliminated and the stresses are substantially confined to those brought about by heat and to compressive and abrasive stresses, thereby making practical the use of a liner composed of a material not otherwise practical.

In accordance with this invention, the liner is constructed in segmental sections which are shrunk into a tubular container under circum-' ferential compression in the usual manner.

When a billet is introduced into the liner and pressure from an extrusion ram is exerted upon it, the plastic material being extruded translates the longitudinal pressure of.the extrusion ram into stresses tending to expand the liner as a whole. These stresses are carried through .the

segments of the liner to the container into which the liner is shrunk and are resisted by the container. The container is shielded by the liner from contact with the heated billet and does not attain the temperature that the liner experiences. Therefore, it can be made of a tougher and more elastic material. As an illustration of a suitable steel for this purpose, one containing .45 carbon; 2.60 nickel; .75 chrome; .40 molybdenum with traces of vanadium, has proven satisfactory when heat treated for maximum strength and ductility at 395 Brinell hardness (3000 kg. load on 10 mm. ball). The liner is substantially free from circumferential tensile stresses and the major stresses in the liner during the extrusion operation are confined to heat stresses and compressive and abrasive stresses, thus permitting the use of a liner material with=high compressive and abrasive stress resistance under heat. A steel suitable for this purpose would be one having the characteristics of the following alloy: 18.0 tungsten; 4.0 chrome; 1.0 vanadium; .50 carbon; heat treated to give maximum strength and ductility at 490 Brinell hardness (3000 kg. load on 10 mm. ball). A further advantage of the segmental construction is that the segments are more readily heat-treated than single piece liners and give increased service life. d

Other objects, novel features and advantages of this invention will become apparent from the following specification and accompanying drawings, wherein: 7

Fig. 1' is an end view of an extrusion cylinder constructed in accordance with the invention;

Fig. 2 is a section on the line 2-2 of Fig. 1; and

Fig. 3 is a section similar to Fig. 2 of a modified form.

The extrusion cylinder illustrated in Figs. 1 and 2 consists of a tubular body l0 formed of I three concentric cylinders and a liner ll shrunk into the inner cylinder. The liner is shown as consisting of three segmental sections, but it is contemplated the liner may be constructed of two or more sections. Each section is tapered over a portion of its length to co-operate with a corresponding suriace in the inner cylinder to prevent longitudinal creeping of the segments with respect to each other and to maintain them in proper position in the body. Each segment of the liner is composed of high strength heat resisting alloy and is properly heat-treated to condition it to withstand the stresses to which it is to be subjected. The cylinders forming the body ID are composed of a heat-treated alloy of great As indicated in Fig. 2, the extrusion cylinder associated with a die D and a ram R, both shown merits havin engaging shoulders to prevent creeping of said segments with respect to each other and to maintain them in proper position in said body.

2. An extr'usion machine container comprising, a tubular body formed of a plurality of concentricgcylinders and a liner composed of material having high wear and compressive stress resist- I ance under heat, said liner being formed from in dotted lines. After a billet has been introduced into the container, it is forced through the liner. and into the die D by operation of the ra n R.

The right-hand end of the liner' is slightly countersunk to facilitate insertion of the billet, 1 and the left-hand ,end is also slightly counter sunk as well as being diverging over a' 'short distance to facilitate removal of the butt. 7

The modification illustrated in Figf3 differs essentially from the modification illustrated in Fig. 2 by the provision ofa shoulder l2 on the liner segments and provisionof a coacting:an- .nular recess in the inner body cylinden: Inthis modification, the shoulder 12 maintainsthe segments in fixed longitudinal position, thereby preventing longitudinal creeping of any" segment relative to the remainder and also relative movement of the liner with respect to the body." Also in this modification, the liner:.may=be straight instead of tapered, as the shoulder is sufilcient to maintain the liner or the segments in fixed .position. I claim: 1. An extrusion machine container comprising, a tubular body formed ofa plurality of concentric cylinders. and a linercomposed of material havinghighwear and compressivestress resistance under heat, said liner being formed from several longitudinally arranged segmental 'sections each tapering externally in its entire length and shrunk within the inner ofsaid concentric cylinders, thesaid inner of said concentric-cylinders having an irmer surface complemental to theexternal surfaceshape 10f said tapering segments whereby substantially all circumferential tensile stresses in said liner during-extrusion are eleminated, the said-stress being=taken :up by said tubular body, and .the tapering'form of said liner and" said inner of said concentric cylinders tendingv during extrusion to increase the tightening pressure between said segments and said inner cylinder and between theosegments themselves, and the inner surface of said inner cylinder and the outer surface of said segthree longitudinally arranged segmental sections each tapering externally and shrunk within the inner of said concentric cylinders, the said inner of said concentric cylinders having an inner 'surface'cornplemental to the external surface I shap'eici said tapering segments, whereby substantially alicircumferential tensile stresses in saidliner duringfextrusion are eliminated, the

said stresses being taken up by said tubular body. and the tapering form of said liner and said inner surface" of said inner of i said concentric cylinders tending during -extrusionto increase the tightening pressure :between said segments and said inner cylinder and between ;the segments themselvesfland the .inner surface of said inner cylinder andtheoutersurfaces of said'segments .;having it annular tshouldered= portions adapted to engage each other. to prevent creeping of said'segments with respect to each other land tomaintainthem in'proper position in said body '3; ;An "extrusion machine container comprising, a tubular body, anda liner therefor composed of material having high wear and compressivestress resistance under heat, said liner being, formed ofseveral longitudinally arranged segmental sections each tapering externally in its entire lengthandshrunk within the said'body, the said bodyhaving an inner surface complemental to the external surface shape of said tapering segments whereby substantially all circumferentialtensilestresses in said liner during extrusion-are eliminated, the said stresses being takenup by said tubular'body, and the tapering form of'sald liner andsaid inner surface of said body tending, during extrusion, to increase the tightening, pressure ,betweensaid segments and said bodyand between the segments themselves,

and the inner surface of said bodyandthe outer surface of saidsegments having engaging shoulders to prevent creeping of' said segments with respect to each other and tomaintain them in proper position in said body.

PERCY L. CLARK.

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