| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a pipe with an inner-surface groove with improved roundness by passing a material pipe where a groove is formed on an inner surface through a plurality of pairs of hand-drum-shaped rolls where each pair of opposing rolls is arranged at a specific twist angle, and rotating the rolls on their own axes at least at a specific speed for performing the calibration machining and diameter-reducing machining of the section of the pipe. SOLUTION: Each pair of hand-drum-shaped rolls 3 is mounted to an inlet 1 and an outlet 2 of a device with an axial body part 10 where the through hole of a material pipe is punched. The pair of rolls 3 is arranged at a constant offset angle for a pipe axis and is rotated on its own axis with the axis of the hand-drum-shaped rolls 3 as a center, and at the same time revolves around the pipe by rotating a holder with a drive part 4. The material pipe that is subjected to inner surface groove machining is inserted from the inlet 1, is passed between the hand-drum-shaped rolls 3 rotating speedily at a speed of 3,000 RPM or higher, and is unloaded from the outlet 2 after it is subjected to calibration and diameter-reducing machining, thus setting the roundness of the pipe with inner-surface grooves to 10μm or less.
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