US2974791A - Extrusion press container - Google Patents

Description

March 14, 1961 R. M. L. ELKAN EXTRUSION PRESS CONTAINER 2 Sheets-Sheet 1 Filed 001;. 9, 19.57

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EXTRUSION PRESS CONTAINER Filed Oct. 9, 1957 2 Sheets-Sheet 2 United States Patent EXTRUSION PRESS CONTAINER Robert Max Ludwig Elkan, Bournemouth West, England, assignor to The Loewy Engineering Company Limited, Bournemouth, England, a corporation of Great Britain Filed Oct. 9, 1957, Ser. No. 689,194

Claims priority, application Great Britain Oct. 9, 1956 2 Claims. (Cl. 207-) It is the general practice to use cylindrical billets as the starting product from which metal billets are extruded on extrusion presses. Consequently, the container of such a press, which receives the billets to be extruded, has a billet chamber of circular cross-section. The casings of these containers have to be of substantial thickness in order to withstand the large stresses which occur during an extrusion operation, and these casings were, therefore, usually very big and costly to manufacture. The Walls of the billet receiving chamber of a container are subjected to intensive wear because of their frictional contact under heavy pressure with the extruded metal. In'order to avoid this wear taking place on the casing, which, as stated before, is an expensive item, it is customary to insert into the casing a liner in the form of a substantially cylindrical sleeve made in one piece. In some cases, the liner is not fitted directly into the casing of the container, but into an intermediate sleeve, called the liner holder. The liner and casing, and, if provided, the liner holder, are assembled together with a forced fit.

It has been proposed to use, instead of cylindrical billets, billets of rectangular cross-section, especially for the extrusion of articles having a cross-section whose overall width exceeds considerably its overall height. Such cross-sections can be more closely matched by rectangular billets than by circular billets, and this permits a reduction in the extrusion pressure, and, thereby, in the tonnage of the press which may be considerable. Presses for the extrusion of rectangular billets must have a container with a rectangular billet chamber.

It has been found that the pattern of the distribution of stresses which occur in such a container during extrusion of rectangular billets is of a special nature. This pattern is essentially difierent from that set up during the extrusion of a circular billet inasmuch as it has pronounced stress concentrations in those parts of the container which are adjacent the corners of'the billet chamber, or adjacent the radial planes passing through those corners. If the part of the container comprising the walls of a rectangular billet chamber were made in one single piece, this part would, under the severe stress concentrations, soon develop cracks at or near the corners or fracture altogether.

In order to avoid these stress concentrations and, at the same time, to facilitate the machining of the container components, the proposal has been made to position a plurality of inserts in a cylindrical cavity of the container of an extrusion press. These inserts have inner faces which are so shaped and spaced-apart from each other that the inner faces of an assembly of inserts form together the walls of a rectangular billet chamber of the desired size. Each insert of an assembly has then at least one inner face forming part of one of the walls of the billet chamber, at least one arcuate outer wall which contacts the cylindrical cavity in the container, which may be either formed direct in the casing, or in the liner, and at least two faces joining the inner to the outer face and in contact with mating faces of the adjacent inserts.

In view of the severe stresses to which the inserts are subjected during extrusionoperations, they must be machined to very close tolerances to minimize clearances between adjacent inserts and between the inserts and the surrounding container component. This makes the inserts expensive to produce, especially as some of their faces may have to be of somewhat irregular shape. As the inserts are in direct contact with the billet metal, and are therefore subjected to friction under extrusion pressure, in the same way as the liner of the conventional type of container, heavy wear occurs at the inner faces of the inserts, which shortens the life of the inserts.

The present invention relates to certain improvements in a metal extrusion press container specially designed for receiving rectangular billets and in which the billet chamber is formed by an assembly of inserts positioned in a circular cavity inside the container.

One of the objects of the invention is to provide improvements which make the use of the inserts a more economical proposition than it has been heretofore, by minimizing the wear at the inserts, and by facilitating the replacement of worn parts.

The objects of the invention will become apparent from the following specification, in which embodiments of the invention are described by way of example with reference to the accompanying drawings.

In the drawings:

Fig. 1 is an end view of a container of an extrusion press into which the invention is incorporated,

Fig. 2 is a partial longitudinal section on an enlarged scale, along line 22 of Fig. 1,

Fig. 3 is a transverse section along the line 3-3 of Fig. 2,

Fig. 4 is a section corresponding to that of Fig. 2 of another embodiment of the invention,

Fig. 5 is a transverse section along line 55 of Fig. 4.

As to be seen in Fig. l, a container for a metal extrusion press comprises a casing 10 having a circular cavity 11 and a sleeve-shaped and substantially cylindrical liner 12 inserted into the cavity 11 with a forced fit. Alternatively, the liner 12 may not be directly inserted into the casing 10, but into a likewise substantially cylindrical liner holder arranged intermediate the liner and the casing. The casing 10 has a rectangular outline. The liner 12 has a cylindrical cavity 13. Positioned into that lastmentioned cavity is an assembly of inserts 14, 15, 16 and 17, each of which has an inner face 14a, 15a, 16a and 17a respectively, and an outer face 14b, 15b, 16b and 17]) respectively, and two side faces 14c, 15c, 16c and 17c respectively, which join the inner and the outer faces. The inner faces 14a to 17a are plane-shaped and form together a rectangular opening oriented along a major axis XX and a minor axis YY. The outer faces 14b to 1717 are arcuate and in contact with the cylindrical cavity 13. The side faces 14: to 17c of each insert are in close contact with mating side faces on the adjacent inserts.

According to the present invention, separate wearplates 18, 19, 20 and 21 are arranged on the inner faces 14a to 17a of the inserts 14 to 17 respectively. These Wear-plates extend over the inner faces of the inserts so as to cover the latter entirely. Any contact of the inserts with the hot billet metal is, therefore, avoided, and the inserts arenot subjected to Wear which otherwise would result from this contact. Any wear is limited to the wear-plates.

The wear-plates 18 to 20 have here the form of rectangles with parallel and plane surfaces. They are therefore easy to machine and can be formed from ordinary strip.

, It is to be understood that the thickness of the wear-plates is such that they form together, when in position on their respective inserts,- a rectangular chamber 22 of the size required for the accommodation of the rectangular billets to be extruded from the press. The height of the inserts can therefore be correspondingly reduced.

Means are provided for attaching the wear-plates to their associated inserts in such -a manner that the wearplates can withstand the forces to which they are subjected, especially during extrusion, without becoming dislodged from the inserts.

In one form of the invention, shown in Figs. 1 and 2, the wear-plates have at their ends outwardly projecting lips 23 and 23 which enter into correspondingly shaped recesses in the respective inserts so as not to protrude over the end-faces of the inserts. If desired, the lips may be extended in the radial direction beyond the inserts so that they engage and enter into further outlying parts of the container assembly. The lips have the purpose of preventing axial displacement of the wear-plates relative to the inserts and they may be fastened to the inserts, as shown in Figs. 1 and 2, by such means as screws 24.

Instead of or in addition to the lips, the wear-plates may be attached to the inserts 14', 15', 16' and 17 by means of dowel pins or screws, the latter being shown at 25 in the embodiment according to Figs. 4 and 5. In the case of dowel pins or screws 25 being provided, the end screws 24 may be dispensed with, but the wear- plates 18, 1,, 20' and 21 may still be formed with lips 23 and 23', whereby the pins or screws 25 are relieved from side thrusts and shear stresses. The lips provided at the die end of the container assembly are firmly held against the die or the die holder by the pressure with which the container is forced into sealing contact with the die in a manner generally known with extrusion presses of conentional types. The die has been indicated at 26 and the die holder at 27 in Figs. 2 and 4.

As a further alternative means for attaching the wearplates to the inserts, shrinking may be used.

In all cases, the wear-plates can be readily removed from their associated inserts without damaging the latter, so that the inserts remain intact and can be used with another set of wear-plates.

As a rule, a single wear-plate is provided in respect of each insert, the wear-plates extending well over the entire area of the inner face of this insert. Alternatively, especially in the case of inserts having large inner faces, a plurality of smaller wear-plates may be provided in respect of each insert, whereby manufacturing of the in serts is facilitated, it being then, for instance, possible to make the inserts from narrower strip than would otherwise have been possible.

Conversely, a common wear-plate may be provided for a number of inserts. It may, for instance, be of advantage, especially in the case of containers of great axial length, to sub-divide the inserts into a number of sections arranged in axial alignment, one behind the other. These sections can be made much smaller and lighter than one insert which extends along the entire length of the container, and their manufacturing will he therefore correspondingly simpler and less costly. The sections forming together one insert may then have a common wearplate attached to their insides, which covers the joints between adjacent sections.

The sub-division of the inserts, which is rendered possible through the provision of the wear-plates, allows it further to utilize the same set of sectionalized inserts for billet containers of different length, one or more sections of suitable length being then added to make up for the increase in length of the container. In this way, the number of inserts to be kept in stock for catering for billets of different length can be considerably reduced.

The present invention makes it further possible to exchange a wear-plate of a certain thickness for another one of ditferent thickness, without changing the insert. In this way, the dimensions of the billet chamber formed by the wear-plates may be altered within certain limits, without having to use a fresh set of inserts. This again reduces the number of inserts which have to be kept in stock.

An extrusion press having a container embodying the present invention can therefore be more readily adapted for the extrusion of billets of difierent sizes, than was formerly possible. In view of the high manufacturing costs of the inserts, it has been hitherto deemed uneconomical to provide special and separate sets of inserts for different sizes of billets, especially when the variation in billet size was only comparatively small, i.e., in the order of an inch or less. This has sometimes been an obstacle to the use of rectangular billets on extrusion presses, and has not permitted to take full advantage of the adaptability of the cross-section of rectangular billets to that of the extruded articles.

A set of inserts, as shown in the drawings, consists of four pieces, 'one for each side of the rectangular billet chamber, so that normally four wear-plates will be provided. It is possible to exchange then either all four wear-plates together, or only a pair of plates which face each other. In exceptional cases, it may also be feasible to take a wear-plate, or pair of wear-plates, out altogether. In this way, the size of the billet chamber defined by the wear-plates can be readily varied.

After the surface of a wear-plate has become worn, the wear-plate can be detached from its insert, and machined down to the thickness which is required for forming a billet chamber of the next larger size. One and the same Wear-plate can therefore be used in succession for different billet chambers and its useful life thereby correspondingly increased.

The side-walls of the wear-plates, with which they are in contact with each other, may be chamfered so that they extend substantially in the direction of diagonals of rectangles.

What is claimed is:

1. A billet container forran extrusion press comprising: an outer casing with a cylindrical cavity therethrough, a cylindrical liner assembled within said cavity, two pairs of inserts positioned in said liner, said inserts each having an arcuate outer surface fitting against the inside bore of said liner, two obliquely disposed fiat, side surfaces, and a flat inner surface, each insert of one pair of said inserts being at each of its obliquely disposed sides in abutting contact with the obliquely disposed side of one of the inserts of the other pairs of inserts, and the flat inner surfaces of all of said inserts cooperating with each other to define a first rectangular cavity separated from said liner at all four sides by said inserts, said inserts meeting at the corners of said rectangular cavity, whereby corner stresses in said rectangular cavity are relieved, and two pairs of fiat rectangular plates secured in said first rectangular cavity to line and cover the same thus forming an innermost second rectangular cavity for the reception of a billet, two of said plates being opposed to one another and each being in abutting contact with three of said inserts, the other two of said plates being opposed to one another and each being in abutting contact with only one of said inserts, each of said plates being in abutting contact with two of the other plates, whereby said second rectangular cavity will, under extrusion pressure, be sealed from the oblique junctions of said inserts.

2. A billet container according to claim 1, in which said flat rectangular plates are provided with outwardly protruding lips which are in engagement with the ends of said inserts for preventing axial displacement of said plates relative to said inserts.

References Cited in the file of this patent UNITED STATES PATENTS 6 Jones Sept. 26, 1916 Clark May 19, 1942 Sequin Nov. 27, 1945 Schlecht et a1. May 17, 1955 Swanson Ian. 6, 1959 FOREIGN PATENTS Great Britain Get. 2, 1957 France May 3, 1907

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