| 摘要 |
An inner grooved tube forming apparatus capable of manufacturing an inner grooved tube with a stable quality by reducing the weight of each member and improving the durability to allow high-speed rotation of a planetary ball die. A grooved plug 12 is fixed to the front end of a mandrel 11, and is in contact with the inner surface of a mother tube 10. Balls 13 are in contact with the outer surface of the mother tube 10. The balls 13 are accommodated inside a ball track retaining outer ring 14. A ball retainer 20 is provided inside the outer ring 14 to retain the balls 13. The outer ring 14 is fixed to a rotating shaft 19 by a cylinder 16 and a front cap 17. A bearing 21 is mounted inside the cylinder 16, and a support member 22 is rotatably supported through the bearing 21 to the cylinder 16. The outer ring 14 and the support member 22 are formed of ceramic, and the ball retainer 20 is formed of synthetic resin. Accordingly, the weight of the apparatus as a whole can be reduced, thus allowing high-speed rotation.
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