Deformation Mechanism of Hot Finish Rolling of Plastic Gears

Abstract

In the present study, the deformation mechanism of hot finish rolling of plastic gears is discussed. This mechanism is important for developing a simulation program for this finishing process. For this purpose, indentation tests of rolling rollers were performed so as to show the relationship between the plastic deformation and various conditions. As a result, it was found that the plastic deformation depends strongly on the Hertzian contact width between rollers. In hot finish rolling, the Hertzian contact width between tooth flanks of die wheel and work gear is generally not so large that the plastic deformation causes changes in the work tooth form. Hence, it can be concluded that the changes in the work tooth form in the hot finish rolling process are not induced by the plastic deformation of the work tooth flank. Thus, we calculated the temperature distribution in the direction of tooth thickness by the finite element analysis of heat conduction. According to the result of this calculation, a melted layer of work tooth flank material exists on the tooth surface. Consequently, the changes in the work tooth form in the hot finish rolling process are induced by the flow of the melted layer.