The blank is subjected to three-direction uneven compressive stress in the closed cavity, and is extruded from the orifice or slit of the mold to reduce the cross-sectional area, and the processing method for forming the desired product is called extrusion.
(1) According to the forming temperature, the extrusion is divided into three types: hot extrusion, warm extrusion and cold extrusion.
(2) According to the relationship between the metal flow direction and the direction of the punch movement, the extrusion forming can be divided into positive extrusion, reverse extrusion and composite extrusion.
Its obvious intermittent characteristics are as follows:
(2) Stabilizing the extrusion stage;
(3) Unstable extrusion stage.