Abstract: The production of an injection moulding of plastics material that includes introducing a supply of plastics material through one or more openings in a mould space, and introducing by way of at least one gas supply passage, a pressurized gas through a separate opening in the mould space into the plastics material within the mould space whereby the gas creates a gas containing cavity in the plastics material. An opening and closing of the gas supply passage is controlled by a valve which is opened by the pressurized gas with the valve featuring a valve port at the outlet end of the gas passage, and a movable valve member extending longitudinally of the gas passage for opening and closing the valve port. The valve member at least when in its extended or valve port open position, protrudes into the mould space and penetrates the plastics material to assist the gas in entering the plastics material.

Abstract: A resin moulding is produced by introducing molten synthetic thermoplastic resin into a mould cavity, sufficient to fill completely the mould cavity. Subsequently, during the cooling of the resin, pressurized gas is introduced into the resin within the mould cavity. The resin moulding cools and hardens in the mould cavity while the gas is maintained under pressure. The mould cavity is designed to manufacture mouldings with unevenly distributed thick walled sections connected to at least one gate for the introduction of the pressurized gas, which flows only within the resin forming the thick walled sections and immediately adjacent areas of the moulding thereby taking up the shrinkage in the resin.

Abstract: An injection molded plastic article is produced by introducing a stream of molten plastic material from an injection molding machine cylinder into an article forming mold space. Pressurized gas is supplied into the interior of the molten plastic material to form a gas containing cavity therein. The plastic material is then allowed to solidify and cool sufficiently so that the article can itself sustain the form dictated by the mold surface. The cavity is vented to reduce the pressure within the cavity to ambient pressure prior to opening of the mold.

Abstract: The invention provides a process and apparatus for producing an injection moulding of plastics material.

Abstract: Apparatus for producing an injection moulding of plastics material comprises means for introducing a supply of plastics material, passage means for communicating the supply means to a mould space, and means for introducing a pressurized gas into the plastics material filling the mould space whereby the gas creates a gas containing cavity in the plastics material and for thereafter relieving the gas pressure within the gas containing cavity before the mould is opened.