Study on manufacture of large size pipe elbows by hydro-bulging tubular single-curvature polyhedron

摘要

This paper presents a method to manufacture pipe elbows by hydro-bulging a tubular single-curvature polyhedron. The basic idea is: first to build an enclosed tubular single-curvature polyhedron using sector single-curvature shell plates; then hydro-bulge the polyhedron to make the tubular single-curvature polyhedron deform plastically into a smooth double-curvature tubular polyhedron; finally to cut the polyhedron into pipe elbows. Main technology steps are: first, to cut steel sheet plates into sheet blanks; second, to form the sheet blanks into single-curvature cylindrical shells; third, to assemble and weld the single-curvature cylindrical shells into an enclosed tubular single-curvature polyhedron; fourth, to hydro-bulge the polyhedron; fifth, to cut the polyhedron hydro-bulged to get pipe elbows. This paper also describes a tubular single-curvature polyhedron hydro-bulging experiment. The results show that the single-curvature polyhedron hydro-bulging technology can be used to manufacture pipe elbows of a large size.