An upper-bound analysis of the closed-die forging of spur gears

Abstract Closed-die forging of spur gears of which the shape of the fillet is a straight line in the radial direction is investigated by means of the upper-bound method. A kinematically admissible velocity field has been newly proposed in this paper: specifically an involute curve has been introduced to represent the tooth profile of the forging die. It was assumed that a constant frictional stress is applied on the contacting surfaces. Utilizing the formulated velocity field, numerical calculations has been carried out to investigate the effects of varying various parameters, such as modules, numbers of teeth and friction factors, on the forging of the spur gears. It was found that forging load or average relative pressure was dependent predominantly on the number of teeth.