A study on the manufacturing process sequence of power assisted steering part

The manufacturing process sequence of a power steering worm gear blank is analyzed. The conventional process sequence for manufacturing power assisted steering (PAS) part contains three distinctive operational stages such as indentation, extrusion, and upsetting, which were originally designed by forming equipment experts. Process conditions such as reduction in area, semi die angle and upsetting ratio are carefully considered to prevent from internal or geometrical defects. The simulation results of the conventional forging process are summarized in terms of deformation patterns, load-stroke relationships and die pressures along the interface for each operational stage. Close investigation of simulation results for current forming process leads to a new process sequence in which the number of operation are reduced into just one operation. Comparisons between the existing and proposed processes are made in terms of maximum force requirement, required forming energy, and process time, respectively. Experiment has been performed to confirm that the proposed process could be applied to replace the existing conventional process sequence and proved the new process to be a safe process sequence for manufacturing PAS part.