| 摘要 |
PROBLEM TO BE SOLVED: To reduce a manufacturing device in size by cooling a tube stock to the temperature equal to or below the freezing point immediately after its inner surface is grooved, and reducing the outside diameter of the tube stock while maintaining the temperature. SOLUTION: A cooling device 10 is arranged adjacent to a first flat die 9 arranged in an advancing direction A side of a tube stock 1 from a roll 7, and a second flat die 12 is arranged adjacent thereto. For example, the tube stock 1 formed of dephosphorized copper is passed through a die 3 in the advancing direction A and the outside diameter of the tube stock 1 is reduced by the die 3 and a plug 4. A grooved plug 6 connected to the plug 4 through a rod 5 is passed, the outer surface side of the tube stock 1 is pressed against the grooved plug 6 by a roll 7 to form a groove 2a on an inner surface of the tube stock 1. Then, the tube stock 1 is further reduced in diameter by the first flat die 9, and cooled to the temperature equal to or below the freezing point, drawn in a drawing-out direction B from the second flat die 12, and formed into the desired outside diameter to obtain an inner-surface grooved tube 2.
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