Cold-forging technique of gear shaft

Abstract

The invention relates to a cold forging technology for a gear shaft; the cold forging technology is characterized in that a new technology of the cold forging forming of the inside and outside and split flow forging, a volume split flow space is arranged between the gear shaft diameter and a concave die, the metal flow resistance is reduced and the unit extruding force carried by the die is lowered by split flow; high-strength die steel and split structure are adopted to produce a gear hole forming die; the concave die is produced by adopting three-layer sleeve prestressed structure so as to improve the compression resistance of the die; a punch is made from an alloy steel material and used for the cold forging and precision forming of a complex gear form blind hole, which improves the forming quality and production efficiency of the gear hole, and lowers the consumption of the raw materials markedly. The cold forging technology of the invention has the advantages of achieving the smooth forming of the gear form blind hole, improving the production efficiency greatly, and improving the quality of the gear hole and the qualification rate of the product markedly.

Description

technical field [0001] The invention relates to a cold forging process of a gear shaft, in particular to a precision cold forging process for a steering system gear shaft of a car, and belongs to the technical field of cold forging precision forming process. Background technique [0002] At present, the gear shaft is to be processed, such as figure 1 , 2 As shown, the shape of the gear shaft is composed of a big end B and a small end C, and the big end B has a rectangular inner hole E and a toothed blind hole A. The traditional processing method is that the shape and the inner square hole are formed by cutting or forging , and the tooth-shaped blind hole is extremely low due to back extrusion (ε F = d 2 / D 2 =0.10~0.12), greatly exceeding the allowable limit deformation of cold forging (ε F ≥0.2), the mold withstands unit extrusion force up to 400Kg / mm 2 , also much more than 250 ~ 300Kg / mm 2 Generally, forging cannot be carried out, so it can only be drilled first an...

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Problems solved by technology

[0002] At present, the gear shaft is to be processed, such as figure 1 , 2 As shown, the shape of the gear shaft is composed of a big end B and a small end C, and the big end B has a rectangular inner hole E and a toothed blind hole A. The traditional processing method is that the shape and the inner square hole are formed by cutting or forging , and the tooth-shaped blind hole is extremely low due to back extrusion (ε F = d 2 / D 2 =0.10~0.12), greatly exceeding the allowable limit deformation of cold forging (ε F ≥0.2), the mold can withstand unit extrusion force up to 400Kg / mm 2 , also much more than 250 ~ 300Kg / mm 2 Generally, forging cannot be carried out, so it can only be drilled first and then cut. The disadvantages of drilling and cutting are insufficient tooth profile strength, poor consistency, low production efficiency and waste of materials.

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