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:
Jul. 28, 1992
Filed:
Mar. 20, 1991
Toshio Kagitani, Kanagawa, JP;
The Japan Steel Works, Ltd., Tokyo, JP;
Abstract
An extruder for extruding a multilayer parison and a method for doing the same. The extruder includes a cylinder having a cylindrical hole and a die slit which extrudes a parison, a ring piston movably fitted in the cylindrical hole, a multilayer head provided between the die slit and the ring piston, and a plurality of annular nozzles concentrically provided in the multilayer head, the annular nozzles facing and being opened to the side of the die slit. The extruder further includes a plurality of flow passages through which material flows, the flow passages communicating with annular nozzles and being circumferentially spaced from one another at equal intervals, control valves for controlling the flow rate of the material passing through the flow passages, each of control valves being connected to the corresponding flow passages, driving member respectively connected to the control valves for driving the control valves, pressure gauges for detecting the pressure of material passing through the flow passages, and control member for inputting each detecting signal from the corresponding pressure gauge and outputting each driving signal to the corresponding driving member in order to apply a constant flow pressure or to apply a predetermined proportional flow pressure.