| 摘要 |
PROBLEM TO BE SOLVED: To product a long size multiple tube aligning the centers of inner/outer tubes by winding a spacer to the outer circumference of the inner tube, longitudinally arranging a tape material on the outer circumference of the inner tube wound with the spacer 3 and seam-welding the tape material. SOLUTION: A spacer 3 having many fins is wound around the outer circumference of the inner tube 2. A tape material 4 is longitudinally arranged on the outer circumference of the inner tube wound with the spacer 3. Both ends 4a, 4b in the width direction of the tape material 4 are rounded by plural pairs of forming roll 5a, 5b and are butted. The tip of a welding torch 7 is arranged near the butted part 6 of the tape material 4, the butted part 6 is seam welded, an outer tube 8 is formed. By longitudinally arranging the tape material formed with longitudinal grooves in plural numbers, rounding and seam welding the tape material, a long size multiple tube can be produced without using the spacer 3. The material of inner tube 2, spacer 3, outer tube 8 is preferably copper (alloy), aluminum (alloy) good in heat conductivity.
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