| 摘要 |
<p>Injection moulding appts. includes a mould carried by a turntable and indexable from an injection station to a station at which the injected material is cooled under pressure. The mould includes a wide sprue opening and injection is effected under relatively low pressure (5000 p.s.i). Pressure is applied during cooling by a hydraulically driven rod which is inserted into the sprue opening. By varying the pressure and temp. during cooling, close control over the degradation of the material can be achieved. A quoted working material is polyethylene terephthalate. High pressure injection gear is avoided and flashing during injection is reduced. Close control can be achieved over the physical properties of the injected article. The arrangement is of particular use in making parison to be later blown to shape.</p> |
