| 摘要 |
Heated material is injected into an annular cavity 175a (figure 4), defined by a pair of mould halves 18, 30, through a sprue passage 175, defined by a sprue bushing 110 and an end portion of a punch 162. After partial cooling of the material, the punch 162 is locked in place while the annular cavity is displaced relative to the sprue passage so that the sprue and a central disc 274 of the moulded disc are severed along the peripheral surface of the punch end portion to leave a moulded annular part (as shown in figure 4). The mould halves are separated while the severed sprue is held to the punch by locking surfaces 173. A sprue ejector member 156 is projected from the punch to eject the sprue from the punch end portion. The finished annular part e.g. a video disc is then removed, carried by the moving platen of the moving mould assembly. A flow regulating injection gate 298 is also provided (see figure 9), and cooling of the mould assembly is effected using spiral cooling channels in a mould portion. <IMAGE> |
