| 摘要 |
An injection moulding apparatus for use in producing centrally-apertured video disc records (10). The apparatus includes first and second mould halves (11, 17) reciprocally movable with respect to each other between a closed position, wherein the two mould halves are in proximity to each other and molten plastic material is injected into a planar, annular cavity defined therebetween to form the record disc, and an open position, wherein the two mould halves are spaced apart from each other and the moulded record disc can be removed. The moulding apparatus further includes first and second annular rings (41, 43) carried by the respective first and second mould halves and defining the outer perimeter of the cavity. The first mould half includes two plates (13, 15) reciprocally vable with respect to each other, with a plurality of compression springs in the form of polyurethane blocks (105) interposed between the two plates, to bias the two annular rings into compressive engagement with each other when a central aperture is being punched in the moulded record disc. |
