Abstract: A process to obtain molecular orientations in perforated plates made of extruded plastic material includes a first heating of the plastic material at an extrusion temperature, the extruding of the plastic material in the form of a perforated plate, a first cooling of said plate, a second heating of the plate at the longitudinal orientation temperature, the longitudinal stretching of the plate, a second cooling of the plate at a temperature approaching room temperature, a third heating of the plate at the longitudinal stabilization temperature, a third cooling of the plate, a fourth heating of the plate at the transverse orientation temperature, the transverse stretching of the plate, a fourth cooling of the plate at the transverse stabilization temperature, and the final cooling of the plate.

Abstract: The invention relates to a process and an equipment to obtain a plate provided with holes directly by extruding plastic materials. The process consists in submitting the material coming out of an extruder head to expansion stresses according to more than one direction and in executing a plurality of perforations in said material submitted to expansion by means of perforating means; the equipment consists of a plurality of perforating devices provided with a reciprocating motion so that they can reach an interference position with respect to the material coming out of the extruder head and of means which, acting at the same time as the perforating devices, are suitable to produce an expansion of the extruded material.