METHOD AND APPARATUS FOR MANUFACTURING INNER GROOVED TUBE AND INNER GROOVED TUBE

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing an inner grooved tube having internal fins having high height and large lead angles at high productivity. SOLUTION: The method includes: a diameter reducing step in which the diameter of a tube stock is reduced using a diameter reducing die and a floating plug inserted into the tube stock by continuously imparting drawing force in a fixed direction to the tube stock; and a form rolling step in which many fins along the grooves of a grooved plug are transferred inside the tube stock with the use of the grooved plug having many spiral parallel grooves on the outer circumferential surface which is freely rotatably connected to the floating plug and a form-rolling tool composed of a plurality of balls or rolls which performs planetary revolution while idly revolving on the outer circumference of the tube stock while being pressed to the side of the grooved plug. The drawing force to the tube stock is controlled so as to fall in the target range on the basis of the detected value while detecting the drawing force. COPYRIGHT: (C)2008,JPO&INPIT