A DESIGN METHOD TO EXTEND THE LIFE OF A MOLD BY COLD UPSET PUNCHING BOLT

In view of the fact that for the cold upset moldof the whole-mold structure, the fatigue life is rathershort, a new design method is proposed to replace the whole mold with themold structure of a three-layer cylinder and thus to change the loadingon the mold and to achieve a longer life.According to the testing results of cold upset bolt and the resultsof stress analysis, empirical formulas are obtained.