PURPOSE: To reduce the friction in case of widening a spiral body and to reduce the widening power by forming a spiral body so as to cause a gap between bar-shaped materials in case of producing a ring blank material with widening and cutting the spiral body being formed from a bar-shaped material.
CONSTITUTION: A bar-shaped material 2 is wound with the lead L having the size like causing the gap C between the bar-shaped materials 2 in case of forming a spiral body 3 with winding in a spiral shape the bar-shaped material 2 of the prescribed sectional shape. The spiral body 3 is cut in its axial direction by a cutter with pressing in its axial direction after widening the spiral body 3 with a small force with sliding plural widening members 9 in radial direction and with setting said spiral body 3 to a spiral widening device 6. The ring blank material 5 where cutting end parts 5a, 5b are mutually engaged is made with pressing simultaneously the end parts 5a, 5b by a pair of presser rods 10, 11 of a pressing force adding device 8. The uniform ring blank material 5 is thus produced easily.
HORII MASAMI
TANAKA KAZUHARU
| JPS51103867A | 1976-09-14 | |||
| JPS5233876A | 1977-03-15 | |||
| JPS5680837U | 1981-06-30 |
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