POSSIBILITIES TO INCREASE THE DURABILITY OF THE ACTIVE PLATES OF THE EXTRUSION DIES

Extrusion is the operation of deformation in volume, through which parts with simple or complex configurations are executed, based on the plastic flow of the material in the space between the punch and the extrusion plate or through the hole of the extrusion plate. Active plates for extrusion from molds must ensure the geometry and dimensional accuracy of the parts and be resistant to high stresses in the process of deformation of the material. The problems that arise in the design of active plates from extrusion dies are: determining the pressure, respectively the tensions; establishing the configuration of the assembly and the geometry of the active area. An increase in the strength of the active plate from the extrusion mold can be obtained by means of shrinkage. It consists of a radial compression of the tube loaded by an internal pressure, through which the maximum normal circumferential tension is reduced. Shrinkage is done by inserting tubes, one into the other, concentric with tightening. Shrinkage can be achieved by the following methods: hot shrinkage; cold shrinkage and shrinkage under cryogenic conditions.