Patent ID: 6154944
Filing Date: 2000-12-05
Classification: B21D,Y10T

Abstract:
A method of forming a tubular member comprising:(a) providing a die having therein a cavity having a cross section corresponding to a configuration of a desired final tubular member;(b) providing a tubular blank having thereon an end portion having an initial cross section transverse to the longitudinal axis of the tubular blank;(c) deforming the end portion of said tubular blank and providing it with a deformed end portion having a deformed cross section transverse to the longitudinal axis of the tubular blank different from said initial cross section, the deformed cross section being a continuously smoothly curved profile;(d) confining said tubular blank in said cavity;(e) sealing said blank by applying to said deformed end portion a sealing member having a resilient sealing portion of continuously smoothly curved cross sectional profile corresponding to said deformed cross section;(f) pressurizing the blank internally to expand it to define the shape of the cavity; and(g) releasing the pressure, removing the sealing member and withdrawing the expanded blank from the die;and wherein in said step of providing a die, said die comprises die sections moving between open, intermediate and closed positions, each die section having a die cavity portion and a mating surface portion, which die sections in the closed position have the mating surface portion of each section in mating engagement with the mating surface portion of each adjacent section on the die cavity portions defining said cavity, and said step of deforming said end portion of said tubular blank comprises placing the blank between the die sections in the open position, and partially closing the die sections to said intermediate position for deforming said end portion, and wherein said sealing member is inserted into the deformed end before the black is confined in the die by moving said die sections to the closed position.