Tail-shrinkage-free back pressure type severe plastic deformation preparation mold for large-size rare earth magnesium alloy ingot blank

Abstract

The invention discloses a tail-shrinkage-free back pressure type severe plastic deformation preparation die for a large-size rare earth magnesium alloy ingot blank, which comprises a convex die arranged on an upper working table of a press machine, a concave die arranged on a lower working table of the press machine, a recoverable residual pressure block and a back pressure plate connected with an ejection cylinder of the press machine, the upper part of the upper cavity is used for placing the blank, the recoverable residual pressing block and the male die, and the lower part of the upper cavity is inclined and inwards contracted to form an extrusion deformation zone communicated with the lower cavity; the recoverable residual pressing block is arranged between the blank and the male die in a spaced manner, is made of a deformable material, can be deformed and filled in the extrusion deformation belt, and can also be deformed and recovered; the upper portion of the back pressure plate is arranged in the lower cavity in a matched mode, so that a forming cavity is formed between the upper portion of the back pressure plate and the lower cavity, and the middle of the upper surface of the back pressure plate protrudes. According to the method, the tail shrinkage phenomenon caused by the existence of pressure residues and non-uniform metal flowing in traditional forward extrusion can be solved, materials are saved, the technological process is shortened, and the strengthening effect is improved.

Description

technical field [0001] The invention belongs to the technical field of metal plastic processing, and in particular relates to a mold for preparing a large-sized rare earth magnesium alloy ingot without back-pressure drastic plastic deformation. Background technique [0002] like figure 1 As shown in the figure, in the metal plastic deformation mold, traditional positive extrusion is the most basic extrusion method. Because of its high three-dimensional compressive stress intensity, it can fully improve the plastic deformation ability of metal materials, and has the advantages of simple process operation and large production flexibility. Features, widely used. But there are still the following shortcomings: (1) The metal flow is uneven during extrusion, the middle flow is fast, and the edge flow is slow, such as figure 2 In the middle, there is a shrinkage, which is not conducive to continuous extrusion; (2) there is a conical deformation zone in the extrusion die, so that...

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Problems solved by technology

But there are still the following disadvantages, (1) The metal flow is not uniform during extrusion, the middle flow is fast, and the edge flow is slow, such as figure 2 The shrinkage shown in A in the middle is not conducive to continuous extrusion; (2) There is a conical deformation zone in the extrusion die, so that there is still excess pressure after the extrusion is completed; the existence of excess pressure and shrinkage makes the extrusion It is necessary to cut the head and tail, resulting in material waste; (3) The preparation of existing large-scale magnesium alloys mostly adopts the "multiple heating and repeated extrusion-upsetting" process, that is: 1) heating homogenization-2) heating-3) Extrusion-4) head and tail removal-5) heating-6) upsetting, repeat 2)-6) three times, a total of 16 processes, the cumulative total strain is 3-4 larger, and has a certain strengthening and toughening effect

However, the gap between each upsetting cycle of this process needs to be reheated. In addition to high energy consumption, each heating will weaken the strengthening effect, which greatly reduces the strengthening effect; in addition, the gap between each upsetting cycle needs to be reheated Cutting is performed on excess pressure, long working hours, low material utilization and production efficiency, making the overall cost high and limiting the application of mass production of magnesium alloys

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