| 摘要 |
PURPOSE:To restrain generation of sectional deformations and wrinkles and to improve the quality of bent products by inserting a flexible elastic tube into a predetermined bending part of a pipe to be bent and bending the pipe with an incompressible fluid pressurized to fill the elastic tube. CONSTITUTION:A pipe 3 is set on a fixing table 4 with a pressing die 2; a flexible elastic tube 8 which is freely expansible in the radial direction and is provided with a blocking member blocks axial elongation is inserted into the predetermined bending part of the pipe 3 with the tube 8 being in a contracted condition. Then, the tube 8 is filled with an incompressible fluid from an introduction pipe 11 so that the tube 8 is in contact with the inner surface of the predetermined part. Next, a rotation table 6 is turned and the tube 8 is moved in proportion to the turning of the table 6. The predetermined bending part of the pipe 3 is bent along a die 5 by the turning of the table 6 and tends to be flat, but the tendency is restrained from the inside of the pipe 3 by the tube 8 and axial elongation of the pipe 3 is also restrained by the elongation blocking member.
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