초록 ▼

A method and apparatus for injection moulding thermoplastic polymers wherein a layer of pressurised gas is provided between at least selected moulded parts (11) and the cooling polymer (28). The gas takes up shrinkage as the polymer cools and allows visual sink marks to be substantially eliminated.

A method and apparatus for injection moulding thermoplastic polymers wherein a layer of pressurised gas is provided between at least selected moulded parts (11) and the cooling polymer (28). The gas takes up shrinkage as the polymer cools and allows visual sink marks to be substantially eliminated. Furthermore, cycle times are reduced, fast cooling being permitted by urging the polymer (28) against the outer mould (27) and cooling the outer mould (27).

대표청구항 ▼

[ What is claimed is:] [1.] A method of injection moulding which comprises:injecting molten thermoplastic polymer material into a cavity defined by separable mould parts, said cavity having at least one wall,allowing the material to cool and solidify in a cooling phase,separating the mould parts and

[ What is claimed is:] [1.] A method of injection moulding which comprises:injecting molten thermoplastic polymer material into a cavity defined by separable mould parts, said cavity having at least one wall,allowing the material to cool and solidify in a cooling phase,separating the mould parts and extracting the solidified material, wherein, during the cooling phases gas is applied under pressure via apertures in the at least one cavity wall to form a pressurised gas layer between the cooling polymer and the at least one cavity wall, wherein the gas is distributed to selected places in the at least one cavity wall via micro-channels in the wall.