Molding of elongate, hollow, biaxially oriented thermoplastic shaped articles
US4421711A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 8, 1981 |
| Grant date | Dec 20, 1983 |
| Priority date | — |
| Expiry date | Jun 8, 2001 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2105/258
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An elongate, rigid, tubular, biaxially oriented thermoplastic, hollow thin-walled shaped article is molded by (i) introducing into an elongate mold cavity, the internal configuration and dimensions thereof corresponding to the exterior surface area of the desired shaped article, and aligning along the longitudinal axis thereof, a hollow tubular thermoplastic preform heated to the biaxial orientation temperature of said thermoplastic; (ii) expanding under internal pressure said heated preform to simultaneously, both longitudinally and transversely, uniformly stretch same, at least to the natural biaxial drawing ratio thereof, but to a value in the transverse direction of less than 100% of that ultimately desired; (iii) next further expanding said heated preform, under increased internal pressure, completely against the internal walls of the mold cavity to thus completely shape said ultimately desired shaped article; and (iv) then cooling said desired shaped article and releasing all pressure therefrom.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.