Clad Gear Deformation by Cold Die Forging with Divided Metal Flow. Quantitative Evaluation of Material Filling Behaviour into Die Cavity.

The relief hole-type divided metal flow die forging process was adopted to fabricate the clad gear in this research. The influence of the deformation condition on the surface pressure and the metal filling into the die cavity were quantitatively evaluated. The purpose in the study is to obtain the optimum deformation condition from the viewpoint of reducing the surface pressure. In the experimental simulation of the die forging, an industrial pure aluminum was employed both for the inner layer material and for the outer layer material of the clad gear. The "2 step-type die forging process" and "Die forging process with mandrel" were adopted to realize the "divided metal flow state". As a result of the experiment, the following two points were clarified. (1) The filling performance of the "2 step-type" is higher by 20∼30% than that of "1 step-type" under the same pressure condition. (2) The pressure of "2 step-type die forging process" to perform the high metal filling into the die cavity is smaller than that of "Die forging process with mandrel". And the filling rate in the case of the mandrel projection height 4 mm is higher than that of 2 mm.