Importance

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Abstract

Proposed is a process for injection molding of products (1) made of thermoplastic material, whose walls (2) enclose a hollow space (3), wherein the molten plastic is injected in a predetermined amount into the cavity or molding nest (6) of a mold (5), during and/or upon which a fluid pressure medium (gas) is applied so that with the formation of the hollow space the molten plastic is distributed along and set against the walls of the cavity or molding nest. The pressure medium (gas) is fed into the cavity or molding nest (6) and into the molten plastic at first essentially only in the direction of flow of the molten plastic and in a quantity and/or at a pressure that causes a void (8) to form within the molten plastic, terminating at a distance from the end of the flow path. Then, with a time lag, more pressure medium (gas) at a higher or increased level of pressure is fed into the cavity and the molten plastic from the end of the flow path for the molten plastic and essentially counter to the direction of flow of the molten plastic, forming a second void (11) which joins with the already existing void (8).

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First Claim