| 摘要 |
PROBLEM TO BE SOLVED: To provide an impact rotary tool which can correctly estimate generation of an impact and generates optimum tightening torque, even if a detecting means of low accuracy is used or an arbitrary speed instruction is given by an operator. SOLUTION: The impact rotary tool has a frequency generator 6, as a rotational angle detecting means, which generates a pulse having a width in inverse proportion to a rotational speed of a motor; and an impact estimating portion 11. In the impact estimating portion 11, by adding a plurality of the generated pulse widths, a first total pulse width is calculated. On the other hand, by adding a plurality of widths that are obtained by integral-multiplying the plural generated pulse widths, a second total pulse width is calculated. A speed variation amount is obtained from difference between the first total pulse width and the second total pulse width. Two peed variation amounts are obtained by making two arbitral numbers that are moved being different from each other, and then an acceleration variation amount is obtained from the difference between the speed variation amounts. When the acceleration variation amount exceeds a threshold value that is arbitrarily determined, the generation of the impact is estimated by the impact estimating portion 11.
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