Precision Extrusion Methods with Double Axis Servo-Press using Counter Pressure

Cold extrusion methods for manufacturing products with high dimensional accuracy utilizing a servo-controlled press are studied. Experiments using lead as a model material are carried out on a servo-controlled double axis press against a flat tool supported by counter pressure. The proposed extrusion methods are analysed with the rigid-plastic finite element simulation by accommodating the pressure-supported tool. It is found that a counter pressure of 50-60 % of the flow stress is needed to flatten the front surfaces of the extruded part. To obtain a long extruded part without under-filling defect at the front corner, reverse extrusion is carried out by pushing back the extruded part after forward-backward extrusion. The proposed extrusion methods are verified with gear parts.