Production of thermally stable oval corrugated tubing for vehicle cable looms

摘要

A tube is extruded from a nozzle and supplied to a corrugator. The tube is expanded against the internal wall of a molding chamber with noncircular circumference. This has varying curvature and/or polygonal form. As a result of this enlargement, and/or as a result of the shape of the extruder nozzle, the tubular section is matched to the internal shape of the chamber. Independent claims are included for various types of tubing produced by the equipment. Preferred features: The profile of tubing thickness and/or its radius variation along the circumference, is such that during enlargement and pressing of the tube on the inner wall of the molding chamber, an at least approximately uniform casing thickness is formed on the internal surface of the chamber. When leaving the extruder nozzle the casing thickness is approximately constant. The nozzle forms the tube with suitable geometric similarity, to match the chamber internal form. The nozzle produces tubing with thicker and thinner walls in correspondence with the radius variation along the chamber walls. Formation is further specified in accordance with the foregoing principles, with suitable variation in nozzle gap width. The nozzle is reinforced in regions of little or no gap curvature. The molding chamber is claimed, essentially as described, and separates as molding jaws. Equipment is further detailed, including quantified operational conditions.