Plastic injection mold assembly and method of molding threaded plastic parts

Abstract

A plastic injection mold assembly is disclosed in which an electric servo motor very precisely controls rotational speeds and amounts of torque applied to cores which extend into the mold cavities as the cores are withdrawn from plastic components being molded and simultaneously directs the linear distances which the cores travel during such withdrawal. A method of accomplishing the molding of plastic components in this manner is also disclosed.

1 . A method of molding a component from a flowing plastic material comprising the steps of 
 providing a molding chamber in an injection mold having a predetermined configuration of the outer form of the component,    providing a core member having a molding segment adjacent one end of the core member disposed in the molding chamber,    filling the molding chamber around the molding segment of the core member with the flowing molding material,    cooling the molding material in the molding chamber until the material is firm enough to retain a shape matching the shape of the molding chamber and the molding segment of the core,    applying rotational power to the core from an electric servo motor,    simultaneously rotating and longitudinally moving the core member until the molding segment adjacent one end of the core member is separated from the component, and    ejecting the component from the molding chamber.    
   
   
       2 . The method of  claim 1  in which the rotational power applied to the core is supplied from an electric servo motor programmed to vary the speed and torque of the core member rotation.