FRICTION JOINING METHOD

PURPOSE:To improve the length accuracy of a suction/exhaust valve for an internal combustion engine. CONSTITUTION:A stem part 4 is turned by a driving motor 10 and a slide table 7 is slidingly moved leftward by a cylinder 12 to bring the left end face of the stem part 4 into contact with the right end face of a bevel part 2. Friction heat is generated at the contact end faces by pressing force and rotation of the stem part 4 when the right end face of the bevel part 2 is pressed with the left end face of the stem part 4 by the cylinder 12. The contact end faces are melted by the friction heat and the position S1 of the contact end faces is moved and displaced to S2. The moving quantity at this time is the initial shift quantity t1. The right end face of the bevel part 2 is further pressed by the left end face of the stem part 4 to move the position S2 of the contact end faces by a prescribed quantity t2 while the rotating speed of the driving motor 10 at the point of the time the initial shift quantity t1 is obtd., by which the total shift quantity t is obtd. The left end of the stem part 4 and the light end face of the bevel part 2 are joined by stopping the rotation of the driving motor 11 at the point of the time the total shift quantity t is obtd. The suction/ exhaust valve for the internal combustion engine is thus obtd.