SU793361A3 - Method of continuous extrusion of long-sized billet - Google Patents

Abstract

1400874 Extruding; drawing WESTERN ELECTRIC CO Inc 17 Nov 1972 [17 Nov 1971] 53178/72 Heading B3P An apparatus for the continuous extrusion of an elongated workpiece 2 through a die 12, Fig. 10, comprises sets of segmented gripping jaws 4 which move in endless paths 6 and co-operate on the innermost part of their paths to feed the workpiece to the die and effect the extrusion. The workpiece 2 is coated with a shear transmitting medium such as beeswax or polyethylene wax in two chambers 82, 83, Fig. 4, before reaching the feeding jaws. A sizing die 73 is provided between the chambers and a wiper 79 removes dirt from the workpiece before coating and a wiper 71 determines the thickness of the coating. The coating acts as a lubricant for both the sizing die and the extrusion die and is progressively pressurized by the jaws to beyond the yield strength of the workpiece. The gripping jaws are moved in the feed direction by staggered pinions 5a-5d, 25a- 25d, Fig. 5, which engage teeth on the outside of the jaws. The pinions are housed in a gear block 14 provided with gears trains and fluid driven motors for the pinions, Fig. 3 (not shown). The gear block 14 has a bore 16 to guide the jaws aligned with the bore of a pressure cylinder 11 and the bore of a further gear block 15 downstream of the extrusion die. The gear block 15 also has pinions 27a-27d engaged with the jaws but these pinions drive fluid pumps so that the jaw feed is retarded by the pinions to keep the jaws closely adjacent. The pressure cylinder 11 is internally lined by a sleeve (34), Fig. 8 (not shown), and a segmented sleeve (38a)-(38d), Fig. 9 (not shown). The segments define bores 40 for electrical heaters and supports guiding bars (42) for the jaws. The jaws are urged inwards by fluid pressure to sets of chambers (52a)-(52d), behind the jaws to pressurize the shear transmitting medium. A set of pressure reducing valves (53a)-(53d), (54a)-(54d), (55a)-(55d), Fig. 8 (not shown), ensure that the pressure in the sets chambers behind the jaws is progressively greater in the workpiece feed direction. The jaws are guided in the curved and straight return paths 7, 8, Fig. 5, by segment cross-section passages in guide blocks, Figs. 6 and 7 (not shown). In operation the jaws 4 closely contact the entire perimetric surface of a length of shear transmitting medium coating on the workpiece 2. The feed of the jaws provide a motive force along the surface of the coating and thereby produce a shear force in the coating medium which is applied as viscous drag to propel the workpiece to the die. The viscous drag produces axial compressive stress in the workpiece. The coating medium cannot escape between the jaws and must pass through the extrusion die. The medium accumulates at the entrance of the die and produces normal compressive stress in the workpiece upstream of the die. The difference between the axial and normal stress is arranged to not exceed the yield strength of the workpiece which may be copper or aluminium.

Description

(54

METHOD OF CONTINUOUS EXTRUDING OF LONG-DIMENSIONAL PREPARATION

The invention relates to the field of processing materials by pressure, in particular to methods for producing long articles with high hydrostatic pressure.

A known method for the continuous extrusion of long workpieces, in which the workpiece is moved to the matrix in the pressure chamber by moving and creating pressure 10 outside the medium in contact with the surface of the workpiece and creating a voltage gradient between the axial tension in the pressure chamber and a normal pressure of 15 mm, not exceeding the elastic limit of the material of the workpiece jjTJ,

The disadvantages of the known solution are the low quality of the products due to the periodicity of the change in pressure at the inlet of the die and, as a result, the distortion of the product profile and the low productivity of the process.

This invention allows to increase the productivity of the process and the quality of the product due to the fact that continuously increasing but the value of the normal pressure creates on the surface of the medium, the opposite of 30

the surface in contact with the workpiece, and the values of normal pressures and axial forces continuously increase throughout the pressure chamber, starting from the entrance of the workpiece to its release through the matrix, to create in it a state of increasing plasticity of the material. Furthermore, said medium, for example beeswax, is in contact in the pressure chamber with the preform over its entire surface.

The proposed method is illustrated in the drawing.

The force required to deform the workpiece is transmitted through an annular layer of viscous medium from the moving cylindrical surface surrounding the workpiece 1. This surface is formed by the movement of a non-. groups of segmented elements 2 along closed trajectories m Z.u. The pressure in the working environment increases from the closing point of the segments to the matrix. Beeswax can be used as a medium.

The segments in the gripping section of the workpiece are in a closed position under the action of the pressure of the liquid applied to their outer surface. The pressure is supplied to

zone, adjacent to the matrix, and then continuously decreases from the matrix in the direction of the closing point of the segment elements. The drive of the segment elements is carried out from the hydraulic motors through gears.

Claims (2)

1. A method of continuous extrusion of a lengthy workpiece, in which the workpiece is moved to the matrix in the pressure chamber by moving and creating pressure medium in contact with the surface of the workpiece and creating a pressure gradient between the axial tensile force and normal pressure not exceeding the elastic limit of the workpiece material, characterized in that, in order to increase the productivity of the method and the quality of the products, continuously increasing in magnitude do not create a normal pressure on the surface of the medium opposite to the surface contacting with the workpiece, and the values of normal pressures and axial forces continuously increase the pressure throughout the chamber, starting from the entrance to the preform prior to its exit through the matrix, to create a state of increasing its ductility material. 2. A method according to claim 1, characterized in that said medium, for example bee wax and i, is in contact in the pressure chamber with the workpiece over its entire surface. Sources of information taken into account in the examination 1. US patent No. 3667267, CL. 72-60 published 06.06.72 (prototype).