The features of double cylindrical braking part with unequal diameters were analyzed. The process of the single step of compound cold extrusion was designed to replace the traditional process of multi-step drawing. In order to reduce extrusion force and to guide the plastic metal flow,some local parts of the hollow blank for extrusion were shaped in advance. The FEM model was built. The changes of punch load, the equivalent stress distribution within the billet and the grain refinement effectiveness were analyzed. The punch-stroke curve shows four stages of the process. Stress concentrates in shunt layer and fillets. Grains in forward extrusion and backward extrusion have the performance of being elongated,being cracked,being gathered and being elongated again by FEA simulation. The process of local grains refinement is similar with the metallographic experiment results. The qualified forming part is obtained from actual extrusion with the research parameters.
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