| 摘要 |
PURPOSE:To manufacture a separator for concrete frame by one process by rolling an external thread on an end of a metallic rod to which a plate nut is fitted at the end using two roller dies for thread rolling having annular grooes at the center. CONSTITUTION:Thread rolling dies A, A' attached to rotation shafts 4, 4' consist of outside dies 1, 1' for external thread forming having collars 3, 3' at the center and inside roller dies 2, 2' for external thread forming. Further, groove rolling dies B, B' for collar forming are provided. A metallic rod 6 is set between roller dies A, A' by a positioning stopper 10. A plate nut 9 which is to be fitted to the end is placed in the annular groove 5 formed by collars 3, 3' etc. Rotation shafts 4, 4' are rotated in the same direction, and brought close to each other. Thus, external threads 7a, 7b having a smooth circumferential face 8 in the middle part and a separator for concrete frame S having a groove 11, a collar 12 etc. are obtained. |
