Research On Driving Gear Of Starter Cold Extrusion Process Simulation And Die Design

Driving gear of starter is one of the important parts in auto motor. Its traditional processing technology is mainly forging stock-turning-gear shaping. This kind of technology not only consumes more materials, its efficiency is very low and machining strength of these parts is not high. While cold extrusion forming is a kind of advanced processing technology without crumbs. Using cold extrusion method to process complex tooth shape parts, it not only has high productivity, but also has better quality.Process simulation of the driving gear’s cold extrusion process by FEM can get metal flow rule, effective stress and strain distribution in workpiece and load-stroke curve during extrusion deformation, so we can develop process analysis and die structure design according to these analysis results, and can decrease the cost and design cycle, improve the design accuracy.At first, the basic principle of cold extrusion is introduced, according to the extrusion principle and driving gear parts drawing, the cold extrusion part is formulated, process program is established, and extrusion pressure is calculated. Then, based on the rigid-plastic finite-element theories, numerical simulation analysis of the formulated process program is developed by using DEFORM, the optimal process program is selected through comparison, metal flow rule, effective stress and strain distribution in workpiece and load-stroke curve during extrusion deformation is obtained, and the relationship between extrusion force and friction coefficient, extrusion speed and blank diameter is also acquired. At last, the punch and die of the optimal process program is designed, the theory analysis and FEM for both the whole die and the combined die is conducted, and the two-layer die has been optimized designed.