| 摘要 |
PROBLEM TO BE SOLVED: To obtain a heating coil suitable for bending of a thick-walled tube.SOLUTION: According to a method for manufacturing a bent metal tube, a metal tube is annularly heated by a coil and is gripped by a clamp arm which can grip a position near a heating part of the metal tube and is rotatable around a support shaft which is separated from said gripping part by a certain distance. The metal tube is propelled in a material axis direction thereby rotating the gripping part by the clamp arm, and is so guided as to be bent in an arc. Next, a bending moment is added to the heating part of the metal tube thereby continuously plastically deforming the metal tube into a bent state, and then, the metal tube is bent. The coil includes a first coil part and a second coil part which are so disposed as to be arranged in a propulsion direction of the metal tube in this order. The first coil part is driven with an output larger than that for the second coil part so that the metal tube is heated to a processing temperature by the first coil part when bending.SELECTED DRAWING: Figure 2 |
