Accession Number : ADD006505

Title :   Prestressed Article.

Descriptive Note : Patent Application,

Corporate Author : DEPARTMENT OF THE ARMY WASHINGTON DC

Personal Author(s) : Figge,Irving E

Report Date : 30 Apr 1979

Pagination or Media Count : 9

Abstract : This invention relates a process for thermoforming prestressed plastic articles, and to articles made by the process. In thermoforming, a sheet of thermoplastic resin is clamped, into a clamp frame and heated. An oven or heat station is utilized, which heats the edges as well as the center of the thermoplastic sheet so that, when it is subsequently delivered to a forming station, an overall temperature balance has been attained. After heating, the sheet is conveyed to the forming station where by one of several methods, it is forced over a mold. In any thermoforming operation residual heat of the plastic must be removed as quickly as possible after forming. After cooling the end product is removed from the forming station and sent to a trim press where it is trimmed from the web.

Descriptors :   *Patent applications, *Thermoplastic resins, *Material forming, *Heating, *Molding techniques, Sheets

Subject Categories : Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE