Abstract: Apparatus for pulsating gas-assisted injection molding hollow tubular plastic parts includes the injection of a molten plastic into a mold cavity in an amount less than the cavity volume and in separate molten plastic flows that flow along the cavity and ultimately unite in a solidifying fusion welding state at an interface. A pressurized gas is injected into the molten plastic to form a central void in the molten plastic extending to opposite sides of the interface leaving a voidless solidifying fusion weld section encompassing the interface. The gas pressure acting on the opposite sides of the interface is trapped and then alternately increased and decreased by a separate gas injection that creates gas pulsations that effect shifting of the molten weld section in opposite directions to force intermingling of the plastic molecules therein and across the interface to enhance the strength of the fusion weld section on solidification and eliminate appearance knit lines.

Abstract: A thin ribbon of paint film is guided and applied directly to hot thermoplastics extrudate just as it exits the extrusion die by a film curving and guide plate and then by a film application wheel that is adjusted so that the film mates with and is laminated to the extrudate with an adhesive bond between the paint film substrate and the extrudate. This eliminates the need for high gloss, high metallic content thermoplastics for use as extrudate such as currently used for finished automotive side molding and allows reground thermoplastics to be used as the extrudate and finished with a paint film covering. The thermoplastic extrusion molding is then compression formed in a preform operation to establish end corners with selected radii for corner sharpness as well as reshape the part cross section. This is accomplished with a die and end cap construction which can be relatively adjusted to provide effective gas venting around the end of the die cavity on die closure.

Abstract: A method of using a plastic extruder equipped with an extrusion die and a gloss controlling auxiliary die to produce an extrudate of polymeric material having controlled gloss appearance comprising the steps of first extruding an extrudate of polymeric material through the extrusion die and then passing the extrudate immediately after exiting from the extrusion die through a gloss controlling auxiliary die which is kept at a temperature either higher or lower than the temperature of the extrusion die.

Abstract: A method of extrusion of a profiled strip of plastic material having a smooth surface finish without any shock line defects by riding the plastic strip on a unidirectionally rotatable roller positioned between the extrusion die lips and the water cooling bath.