| 摘要 |
PURPOSE:To use the entire circumference of round dies by setting the outer circumferential length of the round dies at even times the rolling length of a screw stock to the round dies calculated from the outer peripheral length of the screw stock and the number of rollings and providing key grooves at the intervals of the rolling length of the screw stock to the round dies. CONSTITUTION:The key grooves 24 for mounting the planetary round die 12 to a thread rolling machine are provided to said die and one side wall surface 26 thereof and the end face 28 of the segment die 14 are aligned on one straight line in the radial direction. The distance (d) from the surface 20 where the 1st round die 12a comes into contact with a spacer 12C to the thread peak and the distance (e) from the surface 22 where the 1st segment die 14a comes into contact with the spacer 14C to the thread root are equaled. The distance d' of the 2nd round die 12b and the distance e' of the 2nd segment die 14b are similarly equaled. Further, the outer peripheral length of the 1st, 2nd dies 12a, 12b is set at even times the rolling length calculated from the outer peripheral length of the screw stock and the number of rollings and the plural key grooves 24 are provided at the intervals approximately equal to the rolling length, by which the entire circumference of the round die is evenly used. |
