Failure Mechanism And Local Balance Improvement Of Fine Blanking Die For FAX38/SKH51 High-speed Steel

Fine blanking technology,as a high quality,high efficiency and low consumption precision forming technology,has been widely used in many fields.Especially in the mechanical parts industry and automobile industry,fine blanking technology has become one of the indispensable advanced manufacturing technologies.However,the life of fine blanking die in China is far from the international advanced level.In recent years,the development of high-speed steel has promoted the progress of fine blanking die and promoted the rise of fine blanking industry in China.In this paper,representative FAX38 and SKH51 high-speed steel fine blanking dies with large life difference were selected as the research objects,and fine blanking progressive die was taken as the case.The method of combining experimental research with finite element analysis was adopted.The mechanism of shoulder crack failure and wear failure of FAX38 and SKH51 fine blanking punch was emphatically analyzed,and the improvement of local balance of fine blanking progressive die was further studied,so as to explore the methods to improve the life of highspeed fine blanking die from multiple angles of die material selection,processing and structure.The research was carried out from the following three aspects.Firstly,the microstructure and mechanical properties of FAX38 and SKH51 highspeed steel were studied.The phase structure and phase distribution of the two types of steels were analyzed,the sizes of grains and carbides were counted,and the nano-hardness,rockwell hardness and compressive strength were characterized.The relationship between microstructure and mechanical properties was obtained by discussing the difference of microstructure and mechanical properties between FAX38 and SKH51 high-speed steel,which established the theoretical basis for the failure analysis of fine blanking die.Then,the failure of FAX38 and SKH51 high-speed steel fine blanking punch was studied,and the mechanism of shoulder crack failure and wear failure was analyzed and compared.The results show that the stress concentration caused by the structure and the surface machining defect lead to the initiation of the shoulder crack.The wear resistance of the tool steel is related to the type,size,shape and distribution of carbides.The bonding force between carbides and matrix of FAX38 is stronger,so the wear resistance of FAX38 is better than SKH51.According to the failure mechanism,the improvement measures were put forward,which can provide a reference for improving die life from die material selection and processing.Finally,the finite element static structural simulation was used to analyze the deformation of the fine blanking progressive die at the critical moment.The results show that the stress state of the die is the worst at 1/3 of the blanking time,and the extrusion punch is affected by the uneven deformation of the die during blanking process,which results in eccentric load under a certain lateral force.According to the die deformation,a scheme to improve the local balance was proposed.The simulation results show that the scheme has a significant effect on reducing the die deformation,and the maximum deformation of the extrusion punch is reduced by 63%,which can provide suggestions for improving the die life from the perspective of die structure.