PURPOSE: To improve the productivity of a tube having a petal-shaped fin used for a heat exchanger, etc., by shrinking a wave pitch of a fin material, after being waved, by the difference between a force-feeding speed and a wrapping speed to an inner tube, and wrapping the material around the inner tube while making the material adhere to a soldering tape.
CONSTITUTION: A space between an inner tube 8 and an idle roll 4 is spanned with a soldering tape 5. A blank fin material 1 is formed into a wavy shape by a spur gear device and is forcedly fed into a tunnel guide 3; a blank material 1', formed into a wavy fin, is damped to reduce its wave pitch in sequence by making the end surface of the material 1' adhere to an adhesive flux layer of the upper surface of the tape 5. Next, when the tape 5 is wound up at the feeding speed, equivalent to the lateral width of the material 1', which is obtained by rotating the inner tube 8 a little lower in speed than the force-feeding speed of the material 1' into the guide 3, a fin material 1" having a reduced wave pitch is spirally wrapped around the outer periphery of the tube 8 in a state of adhering to the upper surface of the tape 5 and of an extremely low tension. This formed tube wrapped with a fin is heated to bond the material 1" and the inner tube 5 by soldering, and then a tube having a petal-shaped fin is completed.
SHIMODA NAOKI
SAWADA KENJI
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