Daniel R Lane

US Patent:

52031900, Apr 20, 1993

Filed:

May 30, 1990

Appl. No.:

7/530787

Inventors:

Roy W. Kramer - Houston TX
Robert B. Sivyer - Houston TX
Michael J. Thurmond - Houston TX
Daniel P. Lane - Houston TX

Assignee:

Sivco, Inc. - Houston TX

International Classification:

B21D 3920

US Classification:

72 62

Abstract:

An elongate tubular member with a seamless frusto-conical interior wall surface having a selected taper angle of typically 5. degree. or less which is formed from a metal tubular member of ductile material and circular wall cylinder configuration by the process of sequentially expanding contiguous length segments of the ductile tubular member to an interior frusto-conical wall configuration. The process involves inserting the tubular member into a female die member which defines an interior frusto-conical surface with a selected cone angle of typically 10. degree. or less with the tubular member coaxially aligned with the die member interior surface. Contiguous length segment of the ductile tubular member are sequentially expanded into conforming engagement with the wall surface of the die member wherein the expansion of each length segment selected for expansion to frusto-conical configuration is achieved by application of hydraulic pressure to the interior of the tubular member at a pressure level which exceeds the yield strength of the ductile metal material. Each selected length segment of the tubular member is also of a length predetermined with respect to the taper angle and the ductility and wall thickness of the ductile metal tubular member such that the hydraulic pressure does not exceed the tensile strength of the tubular member. After each sequential expansion, the tubular member is annealed.