Cold extrusion process of planet gear sun gear of transmission of heavy-load truck

Abstract

The invention provides a cold extrusion process of a planet gear sun gear of a transmission of a heavy-load truck. The cold extrusion process includes the following steps that a raw material bar is saw-cut into a specified size; the saw-cut bar is rapidly heated to 950 DEG C + / - 20 DEG C, upsetting and inner hole impact extrusion are completed, a cup-shaped blank is formed, and forging waste heatis saved; spheroidizing annealing treatment of a forging blank is completed, and the hardness of the blank is reduced to be smaller than or equal to 120 HB; punching is completed, and an annular blankis formed; polymer lubricant soaking treatment is carried out after turning is completed, and the blank is air-dried and then prepared for extrusion; tooth form cold extrusion forming is completed; an inner hole and the two end faces of a cold extrusion part are turned, a tooth form is chamfered so that burrs can be removed, an internal spline of the sun gear is broached, and part machining before heat treatment is completed; carburizing and quenching treatment is carried out, carbon potential is controlled at 1% at a strong carburizing stage, the carbon potential is controlled at 0.8% at a diffusion stage, and the surface hardness, the core hardness, the carburized layer depth and the grain size of the quenched part meet the technical requirements; and after a tooth surface is ground, the design requirements are met. The cold extrusion process is low in machining cost and environmentally friendly, and the abrasion resistance is improved.

Description

technical field [0001] The invention relates to an extrusion process, more specifically to a cold extrusion process for a planetary sun gear of a heavy-duty automobile gearbox, and belongs to the technical field of heavy-duty automobile gearboxes. Background technique [0002] The planetary sun gear mechanism of the current heavy-duty gearbox for automobiles participates in the work in low gear and reverse gear, and it bears a large torque and impact load; especially the sun gear, once tooth surface pitting or tooth root crack failures will cause Therefore, the material development, manufacturing process, gear testing and bench testing for planetary gears and sun gears are very strict. At present, planetary gears and sun gears are generally made of ring-shaped blanks by hot forging, finished turning after isothermal normalizing, gear hobbing is used to process the tooth profile, and the tooth profile is ground after carburizing and quenching; the gear accuracy reaches level ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a cold extrusion process for the sun gear of the planetary gear of the heavy-duty auto transmission, aiming at the problems of high cost and high energy consumption in the processing of the existing sun gear of the planetary gear of the heavy-duty gearbox

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