| 摘要 |
PURPOSE:To prevent the deviation of an annular material from the annular inside peripheral surface of a ring groove by the torsion of said material by bending the mandrel material in the ring part by roller pressing to form the annular material and forming the horizontal ring groove on the inside peripheral surface of the annular material. CONSTITUTION:A round pipe is sandwiched as a material 6 for the mandrel 1 of the ring part by a pair of supply rollers 11 and 12 and is thereby advanced; at the same time, said pipe is passed betwen an annular guide 13 and plural bending rollers 16, by which the pipe is continuously bent and the annular material P is formed. A pair of press rollers 7, 8 are provided in the mid-way of bending to press said materials 6. The hollow semi-circular press groove 9 is provided to each of the peripheral surfaces of the rollers 7, 8 and an endless projection 10 is horizontally provided to the deepest part of the semi-circular press groove of the roller 8. The ring groove 2 is horizontally inscribed and formed on the inside peripheral side of the material P when the material 6 passes between the rollers 7 and 8.
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