STRUCTURE FOR SEALING MANDREL OF TUBULAR HYDROFORMING APPARATUS

PROBLEM TO BE SOLVED: To provide structure for sealing a mandrel of a tubular hydroforming apparatus, the structure being made compact and lightweight thereby providing improved work efficiency, and securing durability of a sealing part. SOLUTION: The structure is provided for sealing the mandrel of the tubular hydroforming apparatus which has a sealing part of the mandrel and performs tubular hydroforming by filling superhigh-pressure liquid. The sealing part of the mandrel is provided with: a filling means (2) which is mounted in the outer circumferential part of the mandrel 1a and forms a superhigh-pressure chamber; and an annular movable ring member 4 which is arranged on at least one side of the superhigh-pressure chamber so as to holding this filling means in the axial direction of the mandrel 1a. The movable ring member 4 has: a fixed ring 42 having a wedge-shaped part 42a; and an expansion ring 41 which has a tapered recessed part 41a the inside diameter of which is expanded toward the end face side so as to fit to the wedge-shaped part 42a and is provided with a radially expandable slitting part 41b. In the slitting part 41b, the slitting surface is formed along a direction intersecting the axial direction of the expansion ring 41 from one end face to the other end face from the outer circumferential surface to the inner circumferential surface of the expansion ring 41. COPYRIGHT: (C)2008,JPO&INPIT