| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent cutting failure by performing work so that an orbit by linking points at which a cutter to cut a tube notches the tube in the first place can pass through a part where flexural rigidity to cutting force exerted on the tube by the cutter becomes high among overlapping-contacting margins when the tube is cut. SOLUTION: A tube 1 for a heater core of a vehicular air conditioner is formed in a cross-sectional flat shape by bending a plate-like member, and projecting parts 11a to 11c projected by bending a part and an end part of the plate-like member toward the inside of the tube 1, are formed in a plurality in its long diameter directional almost center part. When such a tube 1 is cut by shear work in the direction for overlapping and contacting with overlapping- contacting margins 11d where a part of the plate-like member overlaps and contacts with each other in the direction orthogonal to the lengthwise direction of the tube 1, it is cut by setting an orbit L by linking points at which a cutter to cut the tube 1 notches the tube 1 in the first place so as to pass through a part B where flexural rigidity to cutting force F exerted on the tube 1 by the cutter becomes high among the overlapping-contacting margins 11d.</p> |
