EVALUATION OF TOOTH PROFILE CHANGES OF SYMMETRIC AND ASYMMETRIC SPUR GEAR FORGING DIES DUE TO SHRINK FIT

The compressive pre-stress due to the shrink fitting cause dimensional changes on the tooth profile of the precision gear forging dies. The accuracy of the gear die is directly affecting the accuracy of the final product. Therefore, the dimensional variations due to shrink fit must be pre-determined and the gear tooth profile on the die insert modified accordingly. In this study, the change of tooth profile of the symmetric and asymmetric precision spur gear forging dies because of shrink fitting are analyzed by finite element (FE) method and the results are compared with the experimental ones. Both the (CMM) measurements and the finite element results of gear dies predict much higher radial displacements than the results of the cylindrical approach (Lame Equations). The amount of radial displacements along the tooth profiles of both symmetric and asymmetric gear dies are not uniform and changing from root to tip of the tooth. The radial displacements of the asymmetric gear forging die are higher than the symmetric one.