Method for producing pipe of heat transmission element utilized as collector plate of solar collector at e.g. wall of building, involves pushing fluid into pipe so that circumferential surface of pipe is pressed against periphery of cavity

摘要

The method involves forming a bent pipe with curvatures from a linear pipe piece by bending processes. The bent pipe is comprised by a mold cavity of a tool, and a fluid e.g. water or oil, is pushed into the pipe by a pump (6) so that the pipe is expanded and a circumferential surface of the pipe is pressed against a periphery of the mold cavity. The pipe is deformed before expansion during closing of the tool, and a circumferential surface-side of the pipe is formed in the mold cavity at a planar surface. An independent claim is also included for a heat transmission element comprising a pipe.