GB2070997A - Container assemblies for extrusion presses - Google Patents

Abstract

A billet container assembly 10 for a metal extrusion press is constructed to accommodate expansion and contraction through the heating cycle while maintaining alignment with the press die. The assembly includes a liner 18 in a support 20 which is supported in a housing 22 by annular adapters 24, 26 permitting dimensional changes of the support relative to the housing. The adapters preferably comprise tapered surfaces (in the form of separate rings or integral with the support) which cooperate with corresponding tapered surfaces of the housing. The degree of taper is chosen to permit relative sliding of the surfaces on the housing and support (or ring) to accommodate expansion and contraction on heating and cooling. <IMAGE>

Description

SPECIFICATION Container assemblies for extrusion presses This invention is concerned with billet container assemblies for extrusion presses, and especially with assemblies which both support and heat metal billets during their extrusion.

Extrusion presses are utilised to press a hot billet of metal or the like through a die. The metal billet, prior to being forced through the die, must be heated to high temperatures, and maintained at the high temperatures until the extrusion operation is completed. The extrusion operation comprises placing both the hot billet and a dummy block immediately adjacent the billet into a close fitting liner of a container assembly. The container liner is supported in a liner support in a container housing. The dummy block transmits the force of the ram to the billet disposed in the line, preventing damaging contact between the billet and the ram, as well as preventing back extrusion of billet residue over the ram. The hot billet is forced through the die to create the extrusion. The container assembly may have a heating means to help keep the billets hot.The container assembly uses the liner to closely define a channel for the billet as well as to provide strength and wear resistance. As the temperature of the liner, the liner support and the container housing varies, the dimensions also vary correspondingly, causing problems in proper support of the container liner and of the liner support and fit as well as general maintenance thereof. U.S. Patent 41'03529 shows a container housing supporting a liner support, itself supporting a liner, but makes no reference to expansion or dimensional problems therebetween.

One of the various objects of the present invention is to provide an improved container assembly for an extrusion press.

A billet container assembly for an extrusion press in accordance with the invention comprises a liner having an opening therethrough defining a longitudinal axis of the container assembly, a liner support arranged radially outwardly of the liner (supporting the liner), an outer housing disposed about the liner support, and means permitting dimensional changes of the liner and liner support with respect to the housing.Preferably the means permitting dimensional changes of the liner and support with respect to the housing comprises an annular adaptor disposed between the liner support and the housing: this is arranged to ailow unrestricted radial and longitudinal expansion and contraction between the liner support and housing as well as full support by the housing around the liner support for maintenance of axial alignment of the liner support (and liner supported thereby) in the extrusion press. Suitably the annular adaptor may comprise a tapered surface integral with an end portion of the liner support.

Preferably, however, the annular adaptor comprises a ring disposed near and around one end portion of the liner support and between it and the outer housing, the ring preferably having an outer peripheral surface tapered with respect to the longitudinal axis of the container assembly. Where the annular adaptor has a tapered surface the outer housing preferably also has a tapered surface making mating sliding contact with the tapered surface of the adaptor to provide support during any longitudinal and radial dimensional changes therebetween, while maintaining alignment of the axis of the liner with the die of an extrusion press including the container assembly. The angle of taper of the tapered surface can be related to the differential expansion for the materials of the liner support and adaptor.Where the adaptor is a ring of radial thickness R and length L, the differential radial expansion is dR and differential longitudinal expansion dL dR - = tangent A dL Thus a most suitable taper angle A can be calculated, knowing the properties of the material of the ring and temperatures involved.

Preferably a container assembly in accordance with the invention has an annular adaptor near either end portion of the liner support.

Preferably a billet container assembly in accordance with the invention comprises heating means arranged within the outer housing to help maintain the temperature of any billet disposed within the container assembly. Conveniently the outer housing of an assembly in accordance with the invention is split along its longitudinal centre plane to facilitate registration of the liner and liner support with the housing.

There now follows a detailed description to be read with reference to the accompanying drawings of first and second container assemblies embodying the invention. It will be realised that these assemblies have been selected for description to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a perspective view of a first illustrative extrusion press container assembly; Figure 2 is a view in section on the line ll-ll of Fig. 1; and Figure 3 is a view of a portion of a second illustrative extrusion press container assembly.

The first illustrative container assembly 10 has a longitudinal axis 1 2 along which the assembly may be slidably arranged for movement toward and away from a die (not shown) on a set of ways in an extrusion press (not shown). The longitudinal axis 1 2 is aligned with a dummy block 14 and a hydraulically powered ram 1 6 (see Fig. 2) all of which are axially aligned with the die. The first illustrative container assembly 10 comprises a cylindrically shaped high temperature steel liner 1 8 (an opening, viz, a bore, of which defines the axis 12) having a diameter which permits relatively close fitting dimensional tolerances with respect to the diameters of the dummy block 14 and the ram 16.A liner support 20, is snugly disposed about the liner 18, and the liner 1 8 is controllably supported in a container housing 22.

A pair of tapered annular rings 24, 26, are disposed between the liner support 20 and the container housing 22, one at each end thereof. The'first annular ring 24. disposed at a downstream end portion of the liner support 20, may have a split retaining washer 28 fixedly arranged in an annular groove 30 to restrain undesired longitudinal movement thereof. The second annular ring 26 is disposed at an upstream end portion of the liner support 20. A second annular retaining washer 31 is disposed longitudinally adjacent the upstream edge of the second annular ring 26 and is secured to the upstream end of the liner support 20 by a circumferential array of bolts 32 extending therethrough.

The tapered annular rings, 24 and 26, each have a tapered surface 34 which comprises an overall conical configuration having a smaller diameter increasing to a large diameter thereof toward each end portion of the liner support 20. The tapered surface 34 is arranged at an angle A with respect to the longitudinal axis 1 2 of the container 1 0. The container housing 22 has an opening at each end thereof, which openings are each defined by tapered surfaces 38, which tapers correspond to those on the rings 24, 26 and provide a smooth, sliding mating therebetween when the liner support 20 is in registration therewith. The tapered surface 34 of each annular ring 24, 26 has a radial thickness R, and a longitudinal dimension L, (see Fig. 2).The first illustrative container assembly 10 has heating means 36 arranged in or around the liner support 20 to heat the liner 1 8 to a particular desired temperature to maintain the heat in any billet disposed therein, thus the temperature range therein is known, i.e. a particular metal being extruded will be preheated to a certain temperature necessary for proper extrusion. The container is cyclically heated from ambient temperature, to nearly the temperature of the billet being extruded. That means that the liner 1 8 and the liner support 20 will expand and subsequently contract, in both the longitudinal and radial dimensions during subsequent heating and cooling periods. Since the material in the annular rings 24, 26 is known, the differential expansion for the particular material is known.

The differential radial expansion may be recited as dR, and the differential longitudinal expansion may be recited as dL. dR over dL equals the tangent of the angle A which is suited for the expansion, contraction and sliding characteristics of the particular material of the annular rings 24, 26, and the particular temperature to which they are to be heated.

This angled sliding arrangement permits stressfree contact between each of the pairs of contiguous tapering surfaces 34, 38 in a supportive relationship therebetween.

The second illustrative container assembly (see Fig. 3) is generally similar except as hereinafter described to the first illustrative assembly and comprises a liner support 40 having a tapered surface 42 which is build into and integral with at least one end of the liner support 40. The container housing 22 may be split in half along a longitudinal plane to accommodate either type liner support 20, 40, to facilitate assembly of the components therein.

During operation of the illustrative container assemblies 10, the heating means 36 heat the liner support 20 or 40 and the liner 1 8 prior to insertion of a billet therein. The,liner 1 8 and liner support 20 or 40 will expand both radially outwardly and longitudinally, with the tapered surface 34 of each annular ring 24, 26 or the tapered surface 42 of the integral liner support 40 sliding against the tapered surface 38 of the container housing 22, providing at each end thereof, full peripheral, smooth, relatively stress-free support interfaces for the liner 1 8 and the liner support 20 or 40 and the container housing 22, while keeping the longitudinal axis of the billet 1 4 and hydraulic ram 1 6 in coaxial alignment with the billet and the die.

The illustrative container assemblies support and maintain alignment of the container in the container housing in an extrusion press, which container is subject to temperature variations as well as dimensional expansion and contraction and permit it to now be handled in a safe and less damage-prone manner.

Claims (11)

1. A billet container assembly for an extrusion press comprising a liner having an opening therethrough defining a longitudinal axis of the container assembly, a liner support arranged radially outwardly of the liner, an outer housing disposed about the liner support, and means permitting dimensional changes of the liner and liner support with respect to the outer housing.

2. A billet container assembly according to claim 1, wherein the means for permitting dimensional changes of the liner and liner support with respect to the outer housing comprises an annular adaptor disposed between the liner support and the outer housing.

3. A billet container assembly according to claim 2, wherein the annular adaptor comprises a ring disposed at and around one end portion of the liner support and between it and the outer housing.

4. A billet container assembly according to claim 2, wherein the annular adaptor comprises a tapered surface integral with an end portion of the liner support.

5. A billet container assembly according to claim 3, wherein the ring has an outer peripheral surface tapered with respect to the longitudinal axis of the container assembly.

6. A billet container assembly according to either one of claims 4 and 5, wherein the outer housing has a mating tapered surface contacting the tapered surface of the adaptor to provide support during any longitudinal and radial dimensional changes therebetween.

7. A billet container assembly according to any one of the preceding claims comprising an annular adaptor near both end portions of the liner support.

8. A billet container assembly according to any one of the preceding claims wherein heating means is arranged within the outer housing to help maintain the temperature of any billet disposed within the container assembly.

9. A billet container assembly according to any one of claims 2 to 8, wherein the outer housing is split along its longitudinal centre plane to facilitate registration of the liner and liner support therewith.

10. A billet container assembly constructed arranged and adapted to operate substantially as hereinbefore described with refer pence to Figs. 1 and 2 of the accompanying drawings.

11. A billet container assembly constructed arranged and adapted to operate substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.