PURPOSE: To easily obtain a high fin tube as an integral body and to reduce the manufacturing cost by rolling a metal tube blank with its piercing by inserting a plug into the prepared hole of the metal tube blank on which a small diameter prepared hole is pierced at the center part and filling up the metal thereof to the groove of a rolling roll.
CONSTITUTION: The metal tube 4 on which a small diameter prepd. hole 4a is pierced at the center part is heated at specified temp. by a heating furnace and transferred to a crossing type inclined rolling mill. The metal tube 4 is rolled in a rolling mill at three places in the peripheral direction by rolling rolls 1, 2, 3 after being bitten in order thereto and subjected to pierced rolling with the prepd. hole 4a being expanded by a plug 5. The metal of the metal tube 4 is flowed in its diameter direction and as the result of being filled up in the groove of the rolling rolls 1, 2, 3, the necessary high fin tube can be obtd. from the metal tube 4.
NAKASUJI KAZUYUKI
HAYASHI CHIHIRO
| JPS62124023A | 1987-06-05 | |||
| JPS63303640A | 1988-12-12 |