A mold for back extrusion of hollow billet to form hollow parts

Abstract

The invention relates to a die used for forming hollow work pieces through backward extrusion of hollow blanks. The die comprises a lower die part and an upper die part and is characterized in that a male die of the upper die part is composed of a fixed male die body and a movable male die body, a flash cavity is formed in the fixed male die body, and a closed type cavity is defined by the fixed male die body and the movable male die body and used for containing flashes generated in a gap between the fixed male die body and the movable male die body. Two processes, namely backward extrusion and heading extrusion, can be completed in the same die; due to the flash cavity, the flexibility ratio and the reliability of the die are improved, forming and manufacturing of the hollow work pieces with holes different in size are achieved, the universality of the die is improved, the production efficiency is improved, and the production cost is reduced.

Description

technical field [0001] The invention belongs to metal material extrusion dies, in particular to a kind of reverse extrusion forming of hollow parts with a central hole at the bottom, which are circular, multi-circular, square, or rectangular in cross-section, and are suitable for cold, Warm and hot extrusion. Background technique [0002] Extrusion process, as one of the processes for the production of non-ferrous metals and steel materials and the forming of parts, is an advanced manufacturing method in modern metal plastic processing. Extrusion as a secondary plastic processing is mainly used in the production of parts. Back extrusion is mainly suitable for the manufacture of hollow parts with circular, multi-layered circular, square, rectangular and other cross-sections, and has been widely developed and applied. [0003] For hollow parts with a central hole at the bottom, the traditional process is to cut the bottom hole after back extrusion of the solid billet. Howev...

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Problems solved by technology

[0007] (1) The integral punch with an inactive mandrel increases the height of the die and the closing height of the die, making it difficult to demould and take out the parts after forming. When the opening height of the press is constant, the length of the hollow parts that can be formed is limited;

[0008] (2) A fixed punch equipped with a moving punch is used. Since there is a gap between the fixed punch and the movable punch, it is easy to generate flashes and cause stagnation, which directly affects the flexibility and reliability of the mold, and affects the Continuity and efficiency of work;

[0009] (3) For these two types of reverse extrusion dies, when the size of the mandrel (or the moving punch) is determined, the size of the center hole at the bottom of the workpiece cannot be changed, the mold has poor versatility, low production efficiency, and high production cost

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