PRODUCTION OF CYLINDRICAL MATERIAL WITH WALLLTHICK PART ON INNER OR BOTH OUTER AND INNER SURFACES FROM CYLINDRICAL MATERIAL WITH WALLLTHICK PART ON THE OUTER SURFACE

摘要

PURPOSE:A cylindrical material consisting of the straight pipe part and the annular and wall-thick part of the different material from that of the straight part is formed into an eclipse in cross section, then is made to contract in the diameter using divided dice, thus forming title cylindrical material having increased strength at the part where the different material is bonded. CONSTITUTION:Previously, wall-thick part T is formed by using a different material K at the position where wall-thick part shall be formed on the inner or inner and outer surface of the straight pipe S and the resulting pipe is plastically deformed into eclipse in cross section at and near the wall-thick part T. Then the pipe is set in a dice consisting of half-divided parts on top and bottom sides and forming the roundness with diameter D when combined, a and a, or b and b, and compressed at and near the eclipse part to shrink the diameter, thus forming said cylindrical material having wall-thick part on both inner and outer or the inner surface.