Patent ID: 8663767
Filing Date: 2014-03-04
Classification: B29C,B29K,F16L,Y10T

Abstract:
1. A hollow profile used in manufacture of a spirally wound double-walled thermo-plastic pipe, the hollow profile comprising: a substantially rectangular-shaped cross section having two side walls, an outer wall, and an inner wall which form a hollow cavity within, wherein the inner wall is intended to form the inner wall of the pipe, and the outer wall is intended to form the outer wall of the pipe, and the inner wall is thicker than the outer wall, wherein the hollow cavity includes two edges where the inner wall joins the two side walls and two other edges where the outer wall joins the two side walls, the edges where the inner wall join the side walls having inner rounding radii that are larger than the rounding radii of the two other edges where the outer wall joins the two side walls, the hollow profile further comprising: a rib extending into the hollow cavity is formed on an inside surface of the inner wall of the profile wherein the rib is arranged on the inside surface of the inner wall in a position midway between the two side walls and extends in a longitudinal direction of the profile along substantially an entire length of the profile, and wherein the inner wall has a thickness that is largest at the rib, has a point of smallest thickness between each side of the rib and the edges where the inner wall joins the side walls, and has an area between the point of the smallest thickness and the edges where the inner wall joins the side walls in which the thickness progressively grows.