Reducer gear tooth precision control

Reducer gear tooth precision control

"Reducer, also known as gearbox, is a structure that changes the speed and torque of the engine. It can change the rotation ratio of the input shaft and the output shaft in stages or fixedly. It is composed of a variable speed rotation structure and an operating structure. It is widely used in automobiles, machine tools and other machines. operating speed and traction device. The transmission is one of the most important components in the automobile transmission system."

The transmission gear is directly related to the driving requirements of the automobile under different conditions such as driving, steering, and acceleration. Therefore, the quality of the gear affects the operation of the gear. There are still many problems in the current transmission gear processing technology. This paper mainly analyzes the problems existing in gear machining, and analyzes the process flow of hobbing, tooth shaving and carburizing and quenching deformation, and determines the method of controlling precision in gear machining process.

Transmission gears are often in a high-load, high-speed operating environment. In addition to normal wear and tear, the gears will also be subject to improper operation by the driver, quality problems of lubricating oil, improper maintenance of gear assembly, etc., resulting in gear impact and poor gear gnawing. and so on, thereby further accelerating the wear of the gears. The transmission is the main part of the car's rotating system. If there is a problem with the gears of the transmission, the driving safety of the car may be affected. Therefore, in the design and production, the precision of the gear is very high, not only the material is required to have certain toughness and wear resistance, but also the material manufacturability is good.

1. Problems existing in the current automobile transmission processing

By changing the transmission ratio of the car and changing the rotation of the crankshaft of the engine, the automobile transmission is used in various driving environments such as starting, driving, accelerating and overcoming road obstacles to drive the traction of the wheels of the car and meet the requirements of different speeds in the car. Because the transmission is constantly changing, the gears of the transmission are often subjected to shock loads, and the gears of the transmission are often damaged, and the gears of the transmission are often damaged. Quality of transmission gears. At present, the gears of automobile transmissions are processed by the rolling shaving method. This kind of processing method is complicated, and the precision of the gear is easily affected by the processing link, so this has also become a difficult point in the processing technology of automobile transmission gears. Gear shaving is the last process in the hobbed shaving process and plays an important role in the accuracy of the gears.

2. Analysis of transmission gear processing technology

Taking a reverse intermediate gear of an automobile transmission as an example, according to the design requirements and driving requirements of the automobile, the gear accuracy of the automobile transmission is required to be at the eighth level.

3. Analysis of test results

It can be seen from Table 1 that the hobbing tooth accuracy is the worst in Fb, Fd, and Fp. From this, it can be concluded that the tooth accuracy is related to the gear blank, machine tool accuracy and fixture accuracy. After testing, it was found that the gear blank, machine tool accuracy and fixture accuracy all meet the production requirements of the transmission gear. However, the gear hobbing process uses a non-tensioning clamp. When the non-tensioning clamp is machined on the workpiece, the installation deviates from the geometric center of the gear, so the accuracy has a large deviation.
Table 2. The shaving tooth adopts the principle of cross-axis helical gear gnawing. The tooth surface of the razor has a small groove for cutting. A certain pressure is applied by radial movement, and the cutting action generated by the relative slip between the gnawing tooth surfaces is used to cut the metal. Machining the gears. In the current production process of automotive transmissions, most manufacturers use axial shaving. Axial shaving In the process of shaving, it is necessary to ensure that the rotation speed between the workpiece and the razor is kept at a constant speed, so that the workpiece with the razor tooth profile corresponding to the tooth profile can be produced. Therefore, if you want to change the shape of the tooth profile, you can change the tooth profile shape of the workpiece, and realize the modification of the tooth profile shape by shaving.

Using the principle of shaving cross-axis helical gears, the tooth direction of the shaving teeth can be corrected through the helix angle of the workpiece and the helix angle of the razor. Tooth shaving is the last process in the transmission processing. In order to ensure the accuracy of the teeth, it must be trimmed according to the tooth shape and direction of the finished product using the principle of shaving to ensure the accuracy of the processed teeth.

Table 3 After the workpiece is heat treated, the gears of the transmission will be deformed after carburizing and quenching. One is the deformation caused by stress, and the deformation caused by stress is more complicated. , the thermal stress phenomenon caused by uneven heating of each component during the quenching process, this deformation is the result of a variety of stresses; another deformation caused by volume change, the deformation caused by volume change is the change in the internal organizational state of the gear material Changes in the volume of other tissues caused by changes in pure volume have certain rules. The deformation after heat treatment is caused by volume change and various stresses.

Conclusion: From the above situation, it is very difficult to use the rolling shaving method to control the deformation problem during the gear processing to the minimum, because the gear will deform under the action of volume deformation and thermal stress. Therefore, in the process of gear processing, various measures must be taken to improve the uniform shape of the gear deformation. In the case of a certain deformation law, the tooth shape and tooth direction are corrected by the tooth shaving process, so as to make the heat treatment tooth shape and tooth shape. The shape meets the design requirements.

4. Conclusion

Gear transmission is widely used in production machinery and equipment, but in the production process, the accuracy of gear transmission is affected by many factors, so analyzing the factors affecting the transmission accuracy of gears and taking effective measures to control it are the requirements of current transmission gear manufacturers. The primary problem to be solved.