Injection molding filter assembly

Abstract

This invention relates to an improved injection molding filter assembly to be located in a passage between the molding machine and the mold to remove contaminants such as wood, paper, or metal from the molten plastic material or melt. The filter assembly has an upstream circular plate located adjacent a downstream circular plate and the plates are secured against relative rotation by pins passing therethrough. The upstream and downstream plates each have a number of circular openings therethrough arranged in concentric circles with each of the openings in each plate partially overlapping at least two openings in the other plate, whereby a plurality of restricted eye-shaped openings are provided through the filter assembly in the abutment plane between the two plates. The filter assembly is securely retained in mating seats in the back plate and the adjoining manifold spreader plate nozzle. The contact plane between the back plate and the manifold spreader plate extends approximately midway the height of the downstream plate of the filter assembly, whereby the filter assembly also acts as a locator to prevent relative lateral movement between the back plate and the manifold spreader plate. The filter assembly according to the invention is durable, relatively inexpensive to manufacture, has an unexpectedly low pressure drop across it and exerts a considerable homogenizing or mixing effect upon the melt flowing through it.

Dependencies are inferred from the claim text.