Method and apparatus for injection and compression molding
US5221509A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1991 |
| Grant date | Jun 22, 1993 |
| Priority date | — |
| Expiry date | Jan 15, 2011 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C2045/5625
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An injection and compression molding apparatus and a method include the steps of supplying molten resin by injecting it into a cavity formed by molds and compressing the resin by applying pressure. In consideration of problems with respect to the occurrence of sink marks in molded products and the deterioration in precision which are caused by the escape of resin during compression and a change in the cavity distance between two molds, an injection and compression molding apparatus and a molding method therefor are capable of resolving the problems and stably producing molded products with good productivity. A gate is closed during compression, and a supplemental amount of resin can be injected after the compression step so as to supply the desired amount of resin in the molded article. The rear side of a movable mold can be held by a mechanical fixing mechanism so that no change is produced in the distance between the molds owing to the pressure applied during injection, and resin is supplied by injection while the distance between the molds being maintained. It is thus possible to stably provide molded products with good appearance, dimensional precision and quality with good pro…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.