To provide a reduction method for contracting a pipe diameter without increasing the wall thickness of the pipe and with a low cost and excellent productiv ity, a manufacturing method for a seamless heat transfer pipe with an inner face groove using the reduction method for the pipe, and the seamless heat transfer pipe with the inner face groove manufactured by the manufacturing method.
In the manufacturing device for the seamless heat transfer pipe with the inner face groove, a flower pattern die 8 supported by a flower pattern die holder 11 is provided on the downstream side of rolling balls and a plug with a groove. In the vicinity of the axis of the flower pattern die 8, a hollow part 14 is provided, and six pieces of projecting parts 13 projecting toward the hollow part 14 are provided to make the shape of the hollow part flower pattern-like viewed from the axis of the flower pattern die 8. Roots 15 are formed among the projecting parts 13, and the shape of the projecting parts 13 and the root is made to be a part of a ball having respectively a fixed diameter. By using the manufacturing device and rotating the flower pattern die 8, the contraction work for the pipe diameter after rolling is conducted with 20% or less diameter contraction rate.
SAEKI CHIKARA
KOSEKI KIYONORI
OSADA TAKU
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