A process method of axial compression expansion forging of hollow structural parts with large cross-section difference

Abstract

The invention relates to a forming method of a hollow part, in particular to an axial pressure expansion forging process method of a hollow structural part with a large cross-section difference. The invention solves the problem of wall thickness reduction existing in the internal high-pressure forming of parts with large cross-section difference at present. The method is as follows: firstly manufacture a preform with a large cross-section difference, and then fill the inside with a fluid medium, which is equivalent to turning the pipe into a solid bar, and then compress the large-diameter area in the axial direction. Gradually paste the mold; finally, further compress the large-diameter area to shorten the length and thicken the wall thickness to the target value, and the forming is completed. The invention is a method for improving the uniformity of the wall thickness of such parts, and at the same time, it can also play the role of improving the shape precision.

Description

technical field [0001] The invention relates to a forming method in the technical field of industrial manufacturing, in particular to an axial pressure expansion forging process for a hollow structural part with a large cross-section difference. Background technique [0002] The large cross-section differential reducer is the key shape of the automobile exhaust system. It is characterized by a large cross-sectional diameter reduction ratio, generally exceeding 1.5. For the parts with large diameter reduction ratio, it was first manufactured by welding and assembling, which has the disadvantages of many processes, easy corrosion of weld seams, and large welding thermal deformation. With the improvement of the quality requirements of automobiles for such parts, the welding and assembly process cannot meet the high-quality manufacturing requirements. In recent years hydroforming has been used to manufacture such parts. Hydroforming avoids the introduction of welds, but there ...

AI Technical Summary

Problems solved by technology

Patent CN106311857A proposes a forming method that can reduce wall thickness reduction, but this method is to compress the cross section, that is, the section perimeter of the formed part is reduced, so it cannot be used for the manufacture of parts with a larger section

More importantly, it does not improve the wall thickness, that is, it cannot make the wall thickness of the part uniform along the axial direction

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