Development trend of automobile gears in Japan

Automobile gears are developing and improving in solving the problems of quality, cost, production efficiency, environment, safety, etc. At present, the world’s automobile industry is in the era of once-in-a-century electric revolution. At the same time, the revolution also requires more and more high and complex automotive gears. This paper briefly introduces the processing, heat treatment and the present situation and development trend of gear steel.

1 Development and progress of gears

A large number of gears are used in automatic transmission (at). It was two speed at half a century ago, and now it has developed to ten level at. The torque of automobile engine increases from 100nm to 700nm. However, the space occupied by the gearbox in the car has not increased correspondingly. In order to meet the requirements of reducing gear noise, small silent at should be installed in a limited space. Therefore, automobile manufacturers need to double the strength of the gear, and reduce the gear accuracy fluctuation to less than 1 / 2 of the original.

At present, in order to further reduce the environmental load, the electric vehicle is being promoted. The noise and vibration of the engine are eliminated by the electric vehicle driven by the electric motor. People also need to reduce the gear noise and vibration, so as to further reduce the environmental load. Therefore, the production enterprises need to do more in-depth research on improving the high precision of gears and reducing the vibration. In addition, in order to maximize the function of the motor, it is necessary to have automatic transmission and reducer for the motor. It can be seen that although automobile gears have made great progress, they still need to continue to develop.

2 Changes in gear manufacturing

The at of automobile has developed from two-stage at half a century ago to ten stage at now, and the engine torque has increased from 100nm to 700nm. The gears used in the early at are carbon steel high frequency quenched gears with short heat treatment time and small environmental load. Later, due to the increase of engine torque and the requirement of high strength of at gear, many at gear materials were changed into alloy steel and gas carburizing steel. The gears with small load and high precision are treated by soft nitriding. The gear with high strength and high precision is made of alloy steel and processed by hobbing, shaving and gas carburizing. The amount of gear treated by high frequency quenching is reduced.

With the development of at technology, the shape of gears used in multi-stage at is more complex and thinner than traditional gears. Therefore, gear is required to be further strengthened. Therefore, after carburizing and quenching, the finishing and shot peening of gears are increased to improve the strength and accuracy of gears. In addition, the application of high-strength special steel in gear has appeared. In recent years, in order to further improve the fuel efficiency of the automobile, the gear surface superfinishing is increased, and the transmission efficiency of the gear is improved.

Gear manufacturing has developed from simple process of gear hobbing and high-frequency quenching for carbon steel to complex process of gear hobbing, shaving, carburizing and quenching, shot peening, tooth grinding and super finishing for alloy steel and high-strength special steel, which has increased gear strength by more than 2 times and reduced gear accuracy fluctuation to less than 1 / 2 of the original. However, the increase of processes, energy consumption, CO2 emissions and rare metals increase the environmental load.

In recent years, the output of soft carburizing gears has been increased, and the application of vacuum carburizing and quenching, nitriding steel and control nitriding technology in automobile gears has been studied and developed. In addition, the further high-strength and high-precision gear, as well as qcdes (the five dimensions of products, namely product quality, cost, on-time delivery, production efficiency and effective service) and other problems are tackled.

With the development of gear steel, gear processing, gear heat treatment and gear finishing technology, the performance of gear has been greatly improved. Designers can’t draw a new gear design drawing by using the existing gear design standards. In this case, cross-border cooperation among gear designers, process designers and material designers is very important. There are many problems to be solved in the realization of qcdes, and we are looking forward to the further development and progress of gear and gear manufacturing technology.

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