| 摘要 |
PROBLEM TO BE SOLVED: To enable a single cutter to deal with whatever width of a cut groove may be required, large or small, by contriving a cutter blade section in such a manner that the lap width of the rotary orbits of blades for cutting the bottom face of the groove mounted on a blade bearing part each on a first and a second base element, laps that of the other blade partially and the lap width is adjustable variably by a pair of threads formed between two bosses. SOLUTION: The width W4 of the rotary orbit of a blade 3 for cutting the bottom face of a groove mounted on a blade bearing part 13, 33 each on a first and a second base element 10, 30 laps that of the other blade partially, and the lap width is adjustable variably by the rotation of threads in a pair of connecting cylinders formed between two bosses 12, 32. In addition, inner bulging parts 13a, 33a are long enough, in the rotating direction, to partially fill a gap 14, 34 formed with the blade ahead. In the rotary direction, each of the bulging parts 13a, 33a comes into contact with a bulging part located before and after the blade ahead and is held by the latter. These differently located bulging parts are rotated all in one piece and advance/retreat in the axial center direction and are freely adjustable so that the lap width of the rotary orbits of the blades is large and small.
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