To provide a method and an apparatus for compression bending processing of a metal tube, capable of performing bending processing at a low cost with high productivity.
The foot of a perpendicular drawn from a bending center O of a metal tube 1 which is to be bent is assumed as a point A. The tip part of the metal tube 1 is clamped to a bending arm 4 at a position a head of the point A to form a predetermined bending radius R. A compression wheel 14 in which r=R+e, with radius being larger only by deviation e, is fixed to the bending arm 4, and a rear part of the metal tube 1 is clamped to a tail clamp device 7. Under a condition in which a conductive member 11 is supported by the compression wheel 14, the metal tube 1 is moved by using an appropriate driving device 9, and the metal tube 1 is heated near the point A by a heating device 19. While expansion of an axial line at a point e deviated from the center of the metal tube 1 is suppressed by using the conductive member 11, bending processing is performed while applying a compression force P (=P1+P2) which is obtained by adding a thrust force P2 of the appropriate driving device 9 to a reactive force P1 generated at the conductive member 11.
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