| 摘要 |
PURPOSE:To produce projecting strips or grooves, which incline so as to conform to the embodiment suitable for the intended use of a bar material, on the outer peripheral surface of the bar material by a method wherein the opening of a tip die consists of a circular hole and longitudinal grooves provided onto the inner peripheral wall of the circular hole and said tip die is rotatably mounted. CONSTITUTION:A core 1 is inserted by means of a feeder 3 into the guide hole 4a of a holder 4 and fed rightwards. An extruder 5 feeds molten synthetic resin material under pressure to the resin flow passage 4b of the holder 4 in order to discharge from a resin discharge port 4c. A tip die 6 is rotatably mounted in such a manner as to closely contact with the end face 40 provided at the annular recess 4d of the holder 4. Resin material is discharged from the resin discharge port 4c directly to the inlet portion 6e of the opening 6a of the tip die 6 so as to continuously and coveringly form a synthetic resin layer 2 onto the core 1 and at the same time to continuously form projecting strips 2a, each of which has a shape corresponding to the shape of a longitudinal groove 4b. With the rotation of the tip die 6, the projecting strips formed onto the outer peripheral surface of a bar material are continuous and inclined with respect to the axis line of the bar material in the direction corresponding to the rotation of a motor. |
