| 摘要 |
PURPOSE:To cut a hollow raw material with small elongation rate in good yield percentage, by turning said hollow raw material to cut V grooves of proper depth on inner/outer peripheral faces respectively at the cutting position thereof and making breaking cut thereon by means of a plastic cutting tool forced in press-contact with one of those grooves. CONSTITUTION:A hollow raw material 2 is turned, and a maching head 3 is advanced so as to cut and machine the outer diameter 11 and the inner diameter 12 by means of a cutting tool 4 and a cutting tool 5 respectively, and after the inner/outer diameter are cut and machined in proscribled sizes, a cutting tool 6 touches the end face of the raw material 2 so as to make cutting process on inner/outer diameter 11, 12 and end face 13 simultaneously. V grooves 15, 16 are formed with the prescribed depth on outer/ inner peripheries of raw material 12 by means of cutting tools 4, 5 respectively. A disk- shaped cutter 7 is pressed on the V groove 15 to make cut in. On the way of cut-in process, the raw material 2 is broken to separate a ring-shaped machined raw material 31. The direction of break is always constant toward the bottom of V groove 16, thus uneven length of raw material 31 being avoided in parallel with improved yield rate of the raw material. |
