A kind of equal channel extrusion die and method for forming billet

Abstract

The invention discloses an equal-channel extrusion mould and a method for molding blank, and belongs to the technical field of extrusion molding of metal materials. The mould comprises a convex mould and a concave mould, wherein the convex mould is composed of a supporting end and an extrusion stem; the supporting end is a cylindrical structure; the extrusion stem is a quadrangular structure; the cross section of the quadrangular structure is in the shape of rectangle; long sides of the rectangle are a, short sides of the rectangle are b, and height of the extrusion stem is 4c; the concave mould is composed of two half moulds, wherein a mould cavity of the concave mould is divided into a guide section, a deformation section and a guide-out section. During blank forming, extrusion equipment drives the convex mould, so that blank sequentially passes though a guide-section mould cavity, a deformation-section mould cavity and a guide-out-section mould cavity of the equal-channel extrusion mould; the shape of the cross section of the blank is changed into a square from a rectangle, and then is changed into the rectangle from the square; multi-pass equal-channel extrusion can be carried out, so that superfine crystal blank with uniform deformation is finally molded. The mould is strong in universality, is good in production cost, is low in load requirement, and can be used for preparing the superfine crystal bank by severe plastic deformation.

Description

technical field [0001] The invention relates to an equal-channel extrusion die and a method for forming a billet, and belongs to the technical field of extrusion forming of metal materials. Background technique [0002] Equal channel angular extrusion (ECAP) is a new forming method for severe plastic deformation (SPD) that effectively refines grains and improves the overall performance of materials. It uses an extrusion die composed of two intersecting channels of equal diameter to make metal A large plastic shear strain is obtained. The structural design of the equal channel can realize the shape and size of the material before and after deformation unchanged, so as to realize multi-pass forming and accumulate large plastic deformation. Based on the concept of equal channels, many new SPD technologies have emerged, such as extrusion twisting (TE), reciprocating extrusion (CEC), elliptical cross-section spiral equal channel extrusion (ECSEE), etc. In the Chinese patent wit...

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Problems solved by technology

Based on the TE forming method, Axi-symmetric forwardspiral extrusion (Mech Mater, 2011, 43(11): 684) and Vortex extrusion (Mater SciEng A, 2011, 530: 469) forming methods have also been proposed abroad, but compared with TE , the effect of forming grain refinement is not good

[0003] Although the above-mentioned equal-channel forming method has excellent effect, there are limitations such as high equipment requirements and large load tonnage. The reason is that the severe large shear strain depends on the complex mold structure

The traditional extrusion die has a relatively simple cavity, which is easy to achieve uniform plastic rheology of the material

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