| 摘要 |
PURPOSE:To manufacture inexpensively a pipe bend of different diameters with less materials and welding parts, by cutting a pipe having a truncated conical shape or a truncated elliptical-cone shape, etc. into two parts, and turning one part around an axial line by a proper angle to weld them together in manufacturing a bend of different diameters. CONSTITUTION:A pipe body 11 formed by winding a stock of steel sheet into a truncated conical shape having an axial line 12 slanted at a proper angle thetato its bottom surface 13 is cut along a cross-sectional line 15 positioned between the bottom surface 13 and its upper surface 14 and slanted at an angle alphaof 45 deg. to the surface 13 to divide it into a pipe piece 11a having a large diameter and a pipe piece 11b having a small one. The piece 11b is turned by 180 deg. around its axial line 12, as shown by an arrow E, in a state of facing the cut surface 11b'' of piece 11b with the cut surface 11a'' of piece 11a. Thus the surface 11b' of the side of minimum cross-sectional area of piece 11b is faced downward, and said surfaces 11b'' and 11a'' are joined together by welding in this state, and a pipe bend 10 of different diameters whose bend angle gamma, between the end face 11a' of the side of maximum cross-sectional area and the piece 11b', is 90 deg., can be manufactured.
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