| 摘要 |
PROBLEM TO BE SOLVED: To improve the initial cutting speed by forming beads such that at the initial stage of use, only a part of a cutting surface of each bead function to minimize cutting resistance in initial cutting of each bead. SOLUTION: Each contact surface 3 with a material to be cut of a number of beads 2 fitted at required spaces to a steel rope as a core wire is shaped such that the middle is increased in thickness like a drum, an inclined surface B sloping one way only is formed, it is rhombic, the central part is reduced in diameter like a twin mountain, or the like, whereby at the initial stage of use, only a part of the cutting surface of each bead functions. The length 3 is increased to exceed the outside diameter as much as possible as far as the cutting speed in the course of use except the initial stage is enough tolerable. Thus, it is possible to overcome the disadvantage that the initial cutting speed is low, which is frequent in a tool containing diamond abrasive grains and also remarkably improve the period of service life.
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