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针对内花键反挤压成形时出现的凸模断裂问题,通过对凸模进行断裂分析,得出断裂的原因为:内花键成形时挤压力较大,阶梯凸模圆角过渡处应力集中,该部位等效应力值为3800 MPa,超过凸模材料ASSAB88的抗弯强度3500 MPa,从而导致凸模在该处产生脆性折断。为避免凸模的早期失效,提出采用组合凸模来避免阶梯凸模圆角过渡处的应力集中问题,数值模拟结果显示,组合凸模工作时无应力集中,成形部分等效应力值约为3150 MPa。生产实践表明,组合凸模可避免凸模的早期失效。
In order to solve the problem of the breakage of the male die during the anti-extrusion of the internal spline, the reason of the fracture is analyzed by the fracture analysis of the punch: the extrusion force is larger when the internal spline is formed, and the stress Concentration, the site equivalent stress value of 3800 MPa, more than the bending strength of the material ASSAB88 punch 3500 MPa, resulting in punches in the brittle fracture. In order to avoid the early failure of the punch, a combination punch is proposed to avoid the stress concentration at the corner transition of the step punch. Numerical simulation results show that when the punch is assembled, no stress concentration occurs and the equivalent stress of the forming part is about 3150 MPa. Production practice shows that the combination of punch can avoid the early failure of punch.