초록 ▼

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 hard

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.

대표청구항 ▼

A method of producing a resin molding comprising introducing molten synthetic thermoplastic resin at an elevated temperature in a mold cavity defining the shape of a resultant molding, introducing pressurized gas into the resin, and allowing the resin molding to cool and harden in the mold cavity wh

A method of producing a resin molding comprising introducing molten synthetic thermoplastic resin at an elevated temperature in a mold cavity defining the shape of a resultant molding, introducing pressurized gas into the resin, and allowing the resin molding to cool and harden in the mold cavity whilst maintaining the gas under pressure, the mold cavity being designed to manufacture moldings with unevenly distributed thick-walled sections connected to at least one gate for the introduction of the pressurized gas, wherein the process comprises filling the mold cavity to its full capacity with the resin and, subsequent to the filling and whilst the resin of the molding cools from said elevated temperature and tends to shrink within the mold cavity, introducing the pressurized gas into the resin within the mold cavity, the gas flowing only within the resin forming the thick-walled sections and immediately adjacent areas of the molding, the gas entering said thick-walled sections and thereby taking up the shrinkage in the resin and forming gas-filled sections within the resin, and the pressure of the gas within the gas-filled sections being maintained during the cooling stage of the molding cycle until the molding can itself sustain the form dictated by the mold surface.