Selection of cutting process parameters for automobile gear hobbing

Automobile gear hobbing has the characteristics of high productivity and good universality. It is a gear processing technology widely used by the backbone enterprises of automobile gear production in China. With the development of automobile industry, gear hobbing technology plays a more and more important role in automobile gear manufacturing. Combined with the practice of automobile gear hobbing and according to the principle of automobile gear hobbing, this paper studies the hobbing cutting process and hobbing technology, and obtains the following conclusions:

  1. Based on the existing research, the mathematical model of automobile gear hobbing cutting process is improved; Combined with the practice of automobile gear hobbing processing, the established automobile gear hobbing processing model is suitable for reverse milling, forward milling or radial cutting of gears, and can be used in the processing of spur and helical cylindrical modified gears, worm gears or other special gears;
  2. The stress analysis results of automobile gear hobbing hob show that when the cutting angle is 0 ° ~ 10 °, the cutting amount of automobile gear hobbing hob is small, the metal removal amount is small, and the tooth load of automobile gear hobbing hob is small; In the cutting angle range of 10 ° ~ 23 °, most of the allowance is cut off by the automobile gear hobbing hob, and the cutter teeth of the automobile gear hobbing hob have a large cutting load; In the cutting angle range of 24 ° ~ 26 °, the cutter teeth exit the cutting state and the load decreases sharply;
  3. The analysis of machining error of automobile gear hobbing hob and the practice of batch machining of automobile gear products show that the error of automobile gear hobbing hob is the main factor affecting the gear profile error. The axial runout error of two end faces of automobile gear hobbing hob, the total meshing error and the helix error of hob tooth are 100% reflected in the gear profile error, 10% of the pressure angle error is converted to the tooth profile error of the gear, and 20% of the radial runout error of the tooth top of the automobile gear hobbing hob will be reflected to the tooth profile error;
  4. Research on design parameters of automobile gear hobbing hob and hobbing cutting test results show that in order to improve chip removal effect and hobbing accuracy, the designed back angle of top edge of automobile gear hobbing hob should be 10 ° ~ 12 °, and the back angle of side edge should not be less than 3 °; The machining efficiency of 80 mm diameter automobile gear hob is 28% higher than that of 100 mm diameter hob; Multi head hobs are not suitable for large axial feed; Under the condition of high-speed cutting, the use of multi head hob for automobile gear hobbing can effectively improve the machining efficiency, but the use of multi head hob will increase the pitch error; The number of hob slots is increased by one time, the theoretical envelope tooth profile error of multi slot hob is reduced by 3-4 times, and the tooth profile accuracy of the cut gear can be improved by using multi slot hob;
  5. Combined with the existing gear processing conditions, according to the influence of the cutting position of the automobile gear hobbing hob on the working load and wear of the cutter teeth participating in the cutting, the calculation method of the installation and positioning of the automobile gear hobbing hob is put forward; According to the principle of maximum machining efficiency and under the control of gear machining accuracy model, the machining process parameters of typical automobile gear products are selected.

Automobile gear hobbing is a complex cutting process, which is affected by many factors. With the continuous improvement of the technical requirements of automotive gear products, the hobbing technology of automotive gear needs to be further improved and developed. In the future work, further research is needed in the following aspects:

  1. Make an in-depth study on the hobbing cutting mechanism of high-speed and high-efficiency automobile gears;
  2. Carry out the development of high-precision automobile gear hobbing hob and the research on hobbing technology of difficult machining materials;
  3. Research on the optimization of processing parameters of automobile gear hobbing, and establish the database of automobile gear processing parameters.
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