Low pressure method for injection molding a plastic article
US5853630A · kind A · utility
Inventor
Key dates
| Filing date | Sep 8, 1997 |
| Grant date | Dec 29, 1998 |
| Priority date | — |
| Expiry date | Sep 8, 2017 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C45/77
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for injecting a plastic material into a mold cavity to precisely fill the mold cavity under low pressure and to avoid packing the mold cavity with plastic material. The plastic material is injected into the mold cavity at a rate sufficient to maintain an unbroken melt front and to avoid any spraying or splashing of the plastic material within the mold cavity. After an initial unbroken melt front is established, the rate at which the material is injected is increased in proportion to the size of the melt front. After a predetermined amount of the material has entered the mold cavity, the material is injected based upon a rate-dominated control algorithm which maintains the unbroken melt front. Once the mold cavity has reached a pre-determined level of fill, the rate-dominated control algorithm is changed to a pressure-dominated control algorithm to prevent overrunning the end point of the mold process and to eliminate splashing and associated backflow problems. The injection pressure is monitored and controlled until the mold cavity has been precisely filled, at which time the injection pressure is maintained until the plastic article has hardened within the mold cavity. By…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.