Method of molding plastic and injection compression molding apparatus using elongatable tie bars
US4849151A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1987 |
| Grant date | Jul 18, 1989 |
| Priority date | — |
| Expiry date | Dec 9, 2007 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C45/561
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method of molding a plastic is initiated by injecting molten resin into a mold at a high pressure. The energy of the high pressure is partially stored in the form of elongation of tie bars of a molding machine. After the gate seals completely, the restoring force of the tie bars due to elastic deformation acts on the molded article as the mold article cools down. Each tie bar comprises a first member having a small modulus of elasticity and a second member. When the elongation of each tie bar is small, only the first member of small modulus of elasticity works. After the elongation reaches a certain amount of .DELTA.l.sub.1, the two members are connected parallel. As a result, the apparent modulus of elasticity of each tie bar increases rapidly. This makes it possible to mold a plastic with high dimensional accuracy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.