Research on working load of opposed dies shearing process (2nd report, influence of working conditions on hydrostatic pressure)

摘要

For every material, there is a certain hydrostatic pressure necessary to prevent crack initiation, which changes during working. From the viewpoints of both blanked product accuracy and tool life, it is important to supply minimum necessary pressure to the blanking section during working. In "Opposed dies shearing process" proposed by one of the authors, it was clarified that the change of the state of hydrostatic pressure is close to the optimum one and is also controllable by working load. Therefore, the required supplement of hydrostatic pressure will be realized through control of the working load. In the former report, the relationship between the working load component and generated hydrostatic pressure was investigated in detail. This paper deals with the variations of the state of hydrostatic pressure throughout the process under various working conditions. Influences of stock length, negative clearance, shape of protruding die and die edge radius are studied quantitatively, and it is found that in the case of work-hardened material, the two parameters of the stock length related to the stock volume to be removed and the shape of the protruding die related to the stock deformation behavior, mainly influence the state of hydrostatic pressure.