Patent ID: 6447710
Filing Date: 2002-09-10
Classification: B29C,F16L

Abstract:
A method for manufacturing plastic tubes, according to which a tube blank brought to a temperature near its molecular orientation temperature is subjected to a biaxial stretching as a result of the radial expansion of the tube blank within a forming barrel, the inner diameter of the forming barrel being slightly larger than the diameter of the plastic tube, with the exception of thermal expansion, with formation of a blister at one end of the tube and controlled displacement of the blister as far as the other end of the tube, and with longitudinal stretching,wherein the radial expansion comprises at least two phases, during a first phase, the tube blank being inflated to an intermediate diameter determined by a double-wall casing introduced into the forming barrel, the casing having a hot fluid circulating between the two walls of the casing; and, during a second phase, the casing being progressively taken out of the forming barrel to allow radial expansion of the plastic tube to the inner diameter of the forming barrel and longitudinal stretching of the tube; and wherein the forming barrel is cooled externally.