The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 15, 1978
Filed:
Dec. 14, 1976
Timothy Stephen Dougherty, Roswell, GA (US);
Western Electric Company, Inc., New York, NY (US);
Abstract
Methods are provided for processing expandable thermoplastic materials with a typical compression relief design extruder screw having a helical flight for advancing and working a thermoplastic material. The screw is modified to shorten the feed and compression sections and to include a plurality of force-producing components in at least the compression section of the screw such that at least some portion of the components in any one turn of the flight lie in one plane essentially normal to the axis of rotation of the screw and such that the walls of the flight are uninterrupted. This arrangement controls the location of the rupturing or fragmenting of what is referred to as the solid bed and controls the manner in which it is fragmented to provide an extrudate at a die end of the extruder which has a constant temperature and which is uniform throughout each successive section of the thermoplastic material. Further, corresponding portions of the successive sections of the thermoplastic material at the die end are caused to have substantially identical time-temperature profiles which is particularly advantageous when extruding expandable insulation in minimizing amplitude of variation in the coaxial capacitance and the diameter of the insulated conductor.