In the actual production process, in addition to die wear, hot forging die cracking is also one of the main forms of die failure. Due to the complex shape of the driven spiral bevel gear blank hot forging blank, the forging cycle is accelerated, the hot forging die cavity is heated and cooled repeatedly after multiple hot forging, and the die has multiple cold and heat cycles. The internal and external bear cold and heat alternating stress, and the forging stress and thermal stress increase, which is easy to produce cracking, and the forging die breaks in serious cases. The cracks on the cavity surface of the hot forging die dominate the life of the die. Therefore, it is very important to study the cracks in the cavity of the hot forging die to prolong the life of the die. The fatigue failure of hot forging die is often caused by the combined action of thermal cycle and mechanical cycle. The causes of cracking of forging die are as follows:
(1) In the process of hot forging, the inner cavity of hot forging die bears too high impact force, which is easy to lead to die failure, which is one of the reasons for cracking in the die cavity. There is an inseparable relationship between die life and die stress, and the maximum equivalent stress of die is closely related to the thermal fatigue cracking of die. With the continuous progress of computer simulation technology, it is possible to analyze the stress and strain of the die in the process of metal plastic deformation, so as to provide an effective basis for improving the stress of the die.
(2) Thermal cracking is related to the surface temperature of the die. Therefore, it is important to understand the surface temperature of the mold. Especially when considering cracking, the maximum temperature reached on the die surface and the range of temperature fluctuation should be mastered. Although it is difficult to directly measure the temperature of the die surface, the finite element simulation technology can be used to obtain the temperature difference inside and outside the die.
Therefore, the analysis of the distribution law of the maximum equivalent stress field and temperature field of the die in the hot forging process of the driven spiral bevel gear blank can provide effective data for thermal fatigue analysis and die life prediction.