Cemented quenching heat treatment method of automobile engine gears

Abstract

A cemented quenching heat treatment method of automobile engine gears comprises a step of carrying out cemented quenching treatment on the forged, pre-heated, machined and hobbed gears. Cemented quenching treatment comprises the following steps that (a) the gears are arranged in a tooling set with a middle round rod in a stacked manner, a cover plate is configured above the gears, and a gear string is formed; (b) multiple gear strings are fed into an Aichelin5 / 3 type multi-purpose furnace to be carburized and quenched, wherein the carburizing and quenching step specifically comprises the stages that firstly, the gear strings are heated to 800 DEG C, then, heat preservation is carried out on the gear strings for 0.2 hour, the carbon potential is 0.3 percent; then, the gear strings are heated to 900 DEG C to be carburized, the strong carburization potential is 1.1 percent, the strong carburization time is 130 minutes; the gear strings are subjected to diffusion, the diffusion carbon potential is 0.7 percent, and the diffusion time is 90 minutes; the gear strings are cooled along with the furnace temperature, and are cooled to 810 DEG C, heat preservation is carried out on the gear strings for 0.2 hour, the carbon potential is 0.7 percent; the gear strings are fed into a front chamber to be quenched, the quenching oil temperature is 50 DEG C, the quenching time is 20 minutes, rapid stirring reaches 1200r / min and the time is five minutes, slow stirring reaches 1100r / min and the time is 15 minutes; and the quenched gear strings are taken out of the furnace; (c) the quenched gear strings taken out of the furnace are cleaned, and low-temperature tempering is further carried out.

Description

technical field [0001] The invention relates to a carburizing and quenching heat treatment method for automobile engine gears, in particular to a heat treatment method for controlling gear deformation of thin-shaped automobile engine gears. The invention belongs to the technical field of metal material heat treatment. Background technique [0002] Automotive engine gears are generally carburized and quenched, and the processing procedures of the gear parts are: forging - pre-heat treatment (normalizing + high temperature tempering) - turning - hobbing - deburring - carburizing and quenching - low temperature tempering - Shot blasting treatment-grinding inner hole-grinding teeth; through carburizing, the gear surface can obtain high carbon content, and after quenching and tempering at low temperature, the gear surface can obtain fine needle-like high-carbon martensite structure, so that the gear surface can obtain high hardness, High wear resistance, thus greatly improving t...

AI Technical Summary

Problems solved by technology

However, due to carburizing and quenching at high temperatures, the gears will produce plane warping deformation. According to the conventional carburizing and quenching method, the plane warping is greater than 0.15mm and accounts for more than 20%. Due to the large plane warping, the grinding teeth cannot be ground. The phenomenon is above 15-20%, which greatly reduces the qualified rate of gears and high scrap rate, which affects production efficiency and increases production costs

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