| 摘要 |
PROBLEM TO BE SOLVED: To provide a circular saw wherein a base metal capable of cutting even in a rotation speed range of >= the minimum critical rotation speed can be provided, it becomes usable in a high rotation speed area though the base metal is thin, a saw thickness can be thinned by a degree that the base metal is thinned, a feed speed can be set large since cutting force per tooth can be decreased by that degree, and therefore work processing efficiency and rate can be improved. SOLUTION: In two modes wherein four slits are bored at intervals of an almost equal central angle on a base metal of a circular saw, two slits opposed to each other with the rotary center disposed between them are provided with an approximately equal length, slits adjoining to each other are set to be different, and the number m of nodal circles of the base metal in the circular saw is 0 and the number of the same nodel diameter n, and when the natural frequency of the circular saw are fn1 (Hz) and fn2 (Hz) (where fn2>fn1) and the natural frequency difference isΔfn=fn2-fn1, its relative natural frequency differenceΔfn/Δfn1 is made >=3.0% for the number n of nodal diameters 3 and >=3.5 for the number n of nodal diameters of 4.
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