US2241543A - Extrusion apparatus - Google Patents

Description

Patented May 13, 1941 nx'rnusron APPARATUS Louis 8. Delta, Jr., WestiieluL-N. 1., assignor to Nassau smelting & Refining Company, Incorporated, New York, N. Y., a corporation of New York Application February 1, 1939, Serial No. 254,079 7 4 Claims.

This invention relates to extrusion apparatus, and more partiwlarly to apparatus for extruding materials in strand form. The invention is especially applicable in the manufacture of tubular strands of one material filled with another.

The product known as cored solder has long been a familiar article of commerce and as an article of use in manufacturing. It consists generally of a hollow or tubular strand of one of several metallic alloys, e. g. lead-tin, having the center of the hollow strand filled with some non-metallic fluxing substance, such as a mixture of rosin and rosin oil. Such strands may be conveniently produced by extrusion of the alloy from an extrusion press through a die to form the outer surface and over a core tube coacting with the die to form the axial bore of the tubular strand. The core material for the strand is fed through the center of the core'tube and into the bore of the strand as the latter takes shape between the die and the core tube.

It will be self-evident that it is materially important in such a procedure that the relation between the core-forming apertrue of the die and the cooperating tip of the core tube be always such as to form the alloy into a tube of substantially constant thickness both longitudinally and circumferentially. The outer diameter of the strand will depend upon the size of the die aperture and also upon the temperature of the alloy being extruded. The wall thickness of the tubular metallic strand depends primarily upon the relative adjustment of the ordinarily tapering tip of the core tube and the die both laterally and longitudinally of the axis of the die. If the two are not adjusted correctly in a lateral direction. the tube formed will be of unequal thickness circumferentially, and the tube wall may even be slit along one side. If the two are not adjusted correctly in a longitudinal direction, the tube wall will not have the desired thickness.

Furthermore, the wall thickness will also depend to some extent upon the temperature and hence the plasticity of the metal being extruded, the colder and stiflfer the metal, the thinner in general being the wall. The temperature of the metal is found in practice to vary more or less during each stroke of the press, as well as from stroke to stroke, and also from day to day; and this variability is not only of metallic mass as a whole but also of different parts of the mass. Hence it is highly desirable that the relative positions of the core tube and die be adjustab e readily both longitudinally and laterally of the die axis in order to compensate for both general temperature changes of the mass of metal being extruded and differential changes within the mass, inorder to maintain the ratio of bore diameter to external diameter of the extruded tube constant.

In an analogous yet quite dissimilar case a wire or strand of relatively harder metal, such as copper or bronze or steel, is provided with a protective weather-resistant coating or sheath of a softer metal, such.- as lead or solder or one of the lead-antimony alloys. This may be done by extruding the sheath directly on the metal strand as the latter is passed through a core tube and die such as are referred to above. The same problems arise relative to the circumferential and longitudinal uniformity of the sheathing on its core. Lead sheathed bronze wire as described is known in the telephone arts as lashing wire and is made and used in large quantity.

An object of the present invention is to provide an apparatus for forming a tubular strand or sheathing of one material filled with or formed upon another material, which apparatus shall be provided with simple, convenient and reliable means of adjustment while in operation to maintain coaxiality of surfaces and uniformity of wall thickness of the tubular strand or sheath.

With the above and other objects in view, one embodiment of the invention may present an extrusion press of generally conventional design having a die block interposed between a pillow block and the extrusion cylinder of the press, a core tube within the die block, and adjustment screws mounted in the dieblock to abut against and adjust the position of the core tube laterally in more than one plane with respect to an extrusion die mounted in the die block, the pillow block being so formed and disposed that all of the adjustment screws are accessible for adjustment while the press is in operation and that the die block may be removed fromthe press for interchange without need to remove any other principal part of the apparatus.

Other objects and features of the invention will appear from the following detailed description of one embodiment thereof taken in connection with the accompanyin drawing, in which the same reference numerals are applied to identical parts in the several figures, and in which- Flg. 1 is a view in front elevation of an extrusion press constructed in accordance with the invention:

Fig. 2 is an enlarged fragmentary sectional view on the lines 2-2 of Fig. 1;

Fig. 3isasimilarvlewonthe line3-3 of 2; ls.4isasimilarvieworntheline4-4oi! Fig. 2; and

- Fig. 5 is a plan view of a pillow block comprising a part of the apparatus.

In the embodiment herein disclosed, an extrusion press of generally famfliar organization has a stationary extrusion ram 26 to coact with an extrusion cylinder 2|. The cylinder 2| rests on a die block 22 which has an extrusion chamber 23 communicating with the chamber 24 of the cylinder 2|. The die block 22 rests on a pillow block 25 which in turn rests on the upper end of a hydraulic ram 26 housed in and coacting with a hydraulic cylinder 21. The ram 26, pillow block 25, die block 22 and extrusion cylinder 2| are secured together by means of screws, 'bolts or the like diagrammatically illustrated at 26-28. All the parts organized as thus far described are familiar and well known in the art of extruding metals and more detailed description of these parts is not necessary here. Preferably the cylinder 2|, die block 22, pillowblock 25 and ram 26 will be separably locked against mutual rotary or other displacement by dowel pins |9-|9. An annular groove 29 is provided near the entrance end of the chamber 23, which, during the operation of the apparatus, becomes filled with the lead or solder being extruded. The solid metal retained in the groove 29 acts as a key to prevent the metal within the chamber 23 from being withdrawn by suction whenever the cylinder 2| starts to move downwardly away from the ram 26.

Mounted in the die block 22 is a die holder 36 having the general form of an exteriorly threaded, horizontally oriented screw having a hexagonal or other shaped head 3| on the outer end, and a coaxial longitudinal bore. 32 therethrough. The inner end of the die holder extends into the extrusion chamber 23. A die 35 having a generally conical countersunk forming surface 33 and a connecting central bore 36 formed therein is positioned within the die holder at its inner end. The bore 36 in the die 35 is smaller than the bore 32 in the die holder 36 and defines the outer diameter of the article being formed by the apparatus. The die holder 33 is mounted in a correspondingly threaded bore 34 in the die block 22.

A core tube 46, also having the general form of an exteriorly threaded screw, is mounted horizontally in a correspondingly threaded bore 44 in the die block so as to be coaxially aligned with the die 35 and to protrude into the extrusion chamber 23. The core tube 46 has a hexagonal or other suitably shaped head 4| on its outer end, and a coaxial longitudinal bore 42 therethrough. A core tip 46 having a generally conically tapered forming surface 43 thereon and a central bore 41 therethrough is secured upon the core tube at its inner end. If plastic material, such as a solder flux, is to be forced through the bore 41 in the tip 46, the bore is made of the proper diameter to form the plastic material into a core of the desired size. when a solid core, such as a wire, is being covered by extruded metal, the bore 41 is of such size that it fits snugly around the core in order to prevent metal from being forced out of a cylinder 23 around the core. Extending from the inner end the care tube is a smooth, unthreaded cylindrical surface 46 the function of which will be pointed out hereinafter.

These two coacting parts, the die holder 36 and the core tube 46, can be adjusted to and from each other, by merely screwing one or the other or both along in the respective bores in which they are housed, to provide the desired separation of the forming surfaces 33 and 43.

A pair of identically similar opposedadjusting screws 66-56, is mounted in corresponding threaded bores 54-54, in the die block 22, to lie in the same horizontal plane as the die holder 36 and core tube 46, and to bear at their inner ends 53-53, against the surface 45 of the core tube. The surface 45 of the core tube is smooth and threadless on this account. The screws 56- 56 are provided with hexagonal or other suitably shaped heads 5|-5| to facilitate their being turned. By loosening either of the screws 66-66 and tightening up the other, the core tube 46 may be bent slightly to effect horizontal lateral adjustment of the forming surface 43 with respect to the forming surface 33.

A single vertical adjusting screw 66 is mounted in a threaded bore 64 in the die block 22, with its axis intersecting the common axis of the core tube 46 and die holder 36, so that the inner end 63 of the screw may be brought to bear up against the under side of the surface 44 of the core tube, preferably in the common vertical plane of the screws 56-56. The screw 66 also is preferably provided with a hexagonal orother suitably shaped head 6|.

The inner end of the core tube 46 tends, in the operation of the apparatus, to be forced down by the pressure transmitted from the ram 26 through material in the chamber 24 and extrusion chamber 23. The screw 66 serves to support the mandrel against this pressure and also in coaction with the pressure to effect vertical adjustment of the surface 43 with respect to the surface 33.

Thus the working tip on the core tube is adjustably yet rigidly held in position in one horizontal direction by the threaded engagement of the core tube with the die block, in the horizontal direction at right angles thereto by the coacting screws 56-56, and in the vertical direction by the coaction of the screw 66 with the downward thrust of the ram 26.

The pillow block 25 is formed with a recess 29 opening preferably from one of the side faces of the block (the left side as shown in Figs. 1

and 3). The recess 29 is preferably tapered, as

shown in Fig. 5, and the pillow block thus has roughly the shape of a U when viewed from above. The screw 66 has its head 6| extending down from the die block 22 into the recess 29 and is thusv at all times accessible through the recess opening. By making the recess 29 tapered, ample space is provided to provide for rotary motion of a suitable tool used to turn the screw 66. The recess 29 is placed preferably at the side because there will be apparatus (not shown) at the rear to feed core material or conduct a core strand into the bore 42 of the mandrel, while in front the product issuing from the bore 32 of the die and ordinarily curving down to a take-up reel or the like (not shown) would interfere with free access, if the recess were in front.

In operation, the hydraulic ram 26 is lowered until the extrusion ram 26 stands clear of the top of the extrusion cylinder 2|. Molten sheathing material of suitable composition is then poured into the chambers 23 and 24 until they are substantially filled. This is ordinarily done at such a temperature that the molten metal solidifies at least partly in the chambers in a short time. If desired, slugs of solid metal may be inserted in the chambers instead of the molten metal. The ram 25 is then actuated to lift the pillow block 25, die b ck 22 and cylinder 2|. The ram 20 enters the cylinder 2| and forces the metal in the extrusion chamber 23 to be extruded through the die 35.

At the same time some suitable core strand or core material, e. 'g. a bronze or other wire, or a molten composition of rosin and rosin oil, is supplied to and, if necessary, forced through the bore 42 of the core tube 40 by any suitable means (not shown). The metal forced to be extruded by the ram 26is formed between the surfaces 33 and 43 and by the control opening in the die 35 into a seamless, continuous, hollow strand of the metal enclosing the coaxial solid strand or core material. This cored strand issues then from the outer end of the bore 32 as a finished product and is disposed of by being coiled up on a spool or in any other desired fashion.

When the ram 26 has reached the end of its upward stroke it is retired to its lowest position and the chambers 23 and 24 are re-filled with metal. A portion of each charge of metal is left in the extrusion chamber 23 at the end of each working cycle, and this amalgamates seamlessly with the metal of the next charge. The operation may be repeated as often as desired, producing a continuous, seamless unbroken cored strand of any desired length.

The average wall thickness of the sheath or hollow metal tube depends, among other factors, on and may be controlled by the separation of the surfaces 33 and 43 which can be adjusted, if necessary, even while the press is in mid-stroke by moving the die holder 30 or the core tube 40, or both of them, longitudinally.

The relative wall thickness at opposite ends of a transverse outside diameter of the strand or the concentricity or coaxiality of the core and sheath or tube depends. among other factors, on and may be controlled by the position of the surface 43 laterally of the axis of the surface 33. In simplest theory, the bores 32 and 42 should be coaxial to produce a perfectly centered core in the strand. However, since some of the metal, moving as a very viscous fluid, divides around the core tube and its several supports and re-unites to enter the die, more or less incalculable disturbing effects are present; and it is found, in practice, that the tip on the core tube must be, so far as can be judged, off the axis of the die a little to produce a metal tube of equal thickness all around. Moreover, the displacement of the core tube to effect this desired result will vary with the sizes of the die, the core tip and their ,bores, with the composition and hence plasticity of both the metal and the core material, with temperature of the air about the apparatus, and perhaps with other causes not known.

Hence it is found to be desirable to provide means to effect adjustment of the tip 46 on the core tube relative to the axis of the die 35. and this is effected by means of the screws 50-50 and 60. They may also be operated to adjust the position of the core tube even while the apparatus is in operation, the screws 505ll being accessible at the sides of the die block 22 and the screw 60 through the recess 29 in the pillow block 25.

Lashing wire, cored solder and analogous products, such as electric cables, may be made in a considerable range of external diameter, and a strand of given external diameter may beprovided, for different uses, with a core of any one of a considerable range of diameters. The external diameter can be, practically, only varied by changing the diameter of the bore 36 in the die 35. This might be done by unscrewing the die holder 30 from the die block 22 and replacing it and the attached die with another holder and die of identical external form and of different bore diameters. However, with a solidified slug of metal present in the chamber 23 this may not be readily accomplished. The next simplest procedure is to remove the entire die block 22 with its die holder 30, core tube 40 and screws 505l| and 60, and set it aside until needed again, replacing it with a similar assembly of die block, die holder, core tube and adjusting screws, in which a core tip and die of the desired size are secured.

To do this, the cylinder 2| may be supported on props or by chains hung from any suitable support, e. g. the top crossbar of the press frame, when the ram 26 is at its uppermost position, and the connectors 2828 loosened sufiiciently or removed. The ram 26 is then retired and the die block 22 and pillow block 25 separate from the cylinder 2| until the die block is free to be lifted free of the dowel pins 19-49 in the pillow block 25 and to be laterally withdrawn, the head of the screw 60 moving freely out through there-- cess 29. The die block assembly may thus be exchanged for another of outwardly identical form but with the desired diameters of core tube bore and die bore, and the cylinder, die block, pillow block and hydraulic ram assembled again in working relation. No part beside the die block assembly and in some instances the connectors 2828 has to be removed from the apparatus to effect the interchange.

The particular press selected to be illustrated herein as embodying the invention happens to be a vertical press with a. movable extrusion cylinder below a fixed coacting ram. It will be obvious that this precise arrangement is not necessary to the invention. The ram can be the moving element instead of the cylinder, or the whole machine may be horizontal instead of vertical, or other similar modifications may occur. However, for the purposes of the appended claims, it is to be understood that the floor of the extrusion chamber 23 in the die block is that wall of the chamber which is opposite to the extrusion ram 20 and lies substantially across the line of motion of the ram relatively to the cylinder. Preferably also the chamber 23 of the die block will be formed to be of slightly smaller diameter at the bottom than at the top.

Also the apparatus as disclosed has separate die block and pillow block to minimize the weight necessary to be moved in effecting the interchange just described. It is believed to be self-evident, however, that these two blocks could also be one integral or combined unit interchangeable as a whole on the supporting ram 26. The embodiment herein disclosed is illustrative only and may be variously modified and departed from without departing from the spirit and scope of the invention as pointed out in and limited solely by the appended claims.

What is claimed is:

1. An apparatus for extruding material comprising a die block formed with an extrusion chamber, material forming means positioned in the chamber, an adjusting screw passing through the floor of the chamber to adjust the position of the material forming means and protruding from the under side of the die block, and a pillow block to support the die block formed with a recess to receive and give access to the adjusting screw.

2. An apparatus for extruding material comprising a die block having an extrusion chamber provided with an entrance to admit material to be extruded, a die holder mounted in an opening in the die block formed at right angles to the entrance, a die positioned in the die holder, a core tube positioned opposite the die in the chamber and at right angles to the entrance to coact with the die in forming material extruded through the die, a plurality of adjusting screws 7 which material forced into the chamber enters to passing through the walls of the chamber from the exterior of the die block and engaging the core tube at right angles thereto, at least one of 20 form a key which prevents material from being withdrawn from/the chamber by suction when the body and the ram are separated.

4. In an extrusion apparatus, a die block having a cavity therein, and means for forcing material into said cavity when moved in one direction and tending to withdraw material therefrom when moved in the opposite direction, said cavity having a groove near the entrance thereof into which material forced into said cavity enters to form a key which prevents material from being withdrawn from the cavity by said material forcing means.

LOUIS S. DEITZ, JR.

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