Optimization of precision forging process parameters for driven spiral bevel gear of automobile rear axle

In the forming process of driven spiral bevel gear of automobile rear axle, the practical application process of precision forging process of driven spiral bevel gear is seriously affected due to excessive forming load and complex metal filling process. If the physical experiment method is used to study the precision forging process of driven spiral bevel gear, it is very difficult to make a systematic and comprehensive analysis of various parameters due to the long cycle and high cost of die design, manufacturing, installation and commissioning. With the rapid development of computer technology, finite element simulation technology has been widely used in metal plastic forming. The combination of numerical simulation technology and physical experiment has become an important method to solve various problems in the process of metal plastic forming.

This paper focuses on the warm precision forging process and cold finishing process of the optimal scheme of the precision forging process of the driven spiral bevel gear of the automobile rear axle, and comprehensively analyzes the simulation results from the aspects of grid division, stroke load curve, equivalent stress, equivalent strain, metal flow law and temperature distribution, and obtains the following laws:

(1) The warm precision forging process of the precision forging process of the driven spiral bevel gear of the automobile rear axle can be divided into four stages: the upper die pressing blank stage, upsetting stage, tooth shape forming stage and flash forming stage. The spiral bevel gear can be divided into two parts: large deformation area (tooth shape part) and small deformation area (lower part of the gear).

(2) When the upper die is pressed into the blank, at this time, the metal of the tooth root part flows to the tooth top part, the load increases uniformly, the equivalent stress and equivalent effect of the tooth part increase, and the metal temperature of the tooth part increases slightly under the action of deformation work.

(3) In the upsetting stage, the metal of spiral bevel gear blank flows along the radial direction under the pressure of the upper die, and the load increases slowly. The equivalent stress of the tooth profile decreases gradually, and the equivalent strain increases gradually; The equivalent stress at the bottom of spiral bevel gear increases gradually, and the equivalent strain remains basically unchanged.

(4) In the tooth forming stage, the metal of spiral bevel gear blank flows into the tooth cavity and fills the whole cavity. The tooth cavity is filled, and the deformation resistance of spiral bevel gear blank increases rapidly. In addition, the metal flow space is narrow and the friction force increases, so the load increases rapidly. The equivalent stress of the tooth part continues to decrease, the equivalent strain continues to increase, and the increase of deformation resistance leads to the increase of deformation work, which makes the metal temperature of the tooth part rise rapidly. For the lower metal of spiral bevel gear, the equivalent stress, equivalent strain and temperature have little change.

(5) In the process of forming flash, the excess spiral bevel gear blank metal flows into the flash groove. At this time, the load floating change, equivalent stress, equivalent effect change and temperature change are basically consistent with the tooth shape formation stage. When clamping, the tooth shape temperature of the metal will reach the highest, about 900 ℃.

(6) In the whole warm precision forging process, the deformation mainly occurs in the large deformation area, the metal equivalent stress in this part gradually decreases, the equal effect change gradually increases, the metal flow is complex, the flow velocity is fast, and the temperature increases obviously; In the small deformation zone, the metal shape changes little, and the changes of equivalent stress, equivalent strain and temperature are not obvious.

(7) In the cold finishing process, the deformation mainly occurs in the tooth profile, and the area with the largest deformation is mainly concentrated on the upper surface of the tooth profile. The cold finishing process is mainly to improve the dimensional accuracy of the tooth profile of spiral bevel gear. The load, equivalent stress and equivalent strain will increase with the increase of stroke. The maximum load and maximum equivalent stress in cold finishing process are larger than that in warm precision forging process, while the maximum equivalent strain is smaller than that in warm precision forging process.

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