Patent ID: 7776248
Filing Date: 2010-08-17
Classification: B29C,F16L,Y10T

Abstract:
1. A method of forming a feature in a pipe wall of a plastic pipe, the pipe wall having a first surface disposed opposite a second surface, the method comprising: (i) providing a heating source for heating the first surface of the pipe wall; (ii) providing a cooling source for cooling the second surface of the pipe wall; (iii) providing a localized temperature gradient across the pipe wall between a localized portion of the first surface and a localized portion of the second surface by utilizing the heating source to apply heat to the localized portion of the first surface and utilizing the cooling source to remove heat from the localized portion of the second surface; and (iv) concurrent with (iii), bending the pipe wall at the localized portions of the first and second surfaces to form the feature, wherein the feature has a convex surface formed from the localized portion of the first surface and a concave surface formed from the localized portion of the second surface, wherein the localized temperature gradient provided across the pipe wall during bending of the pipe wall in (iv) causes a neutral axis of bending in the pipe wall to shift toward the concave surface and away from the convex surface and compressive strain which arises at and adjacent the concave surface during formation of the feature to be reduced.