| 摘要 |
A hand-held powered screw tightening tool is provided with a detecting means to detect a rotation angle of a rotary member in a clockwise direction and a counterclockwise direction. In screw tightening, an angle obtained by subtracting a cumulative total of the rotation angle of the rotary member with rebound, if any, in a counterclockwise direction from a cumulative total of the rotation angle of the same in the clockwise direction is detected and accumulated as a total rotation angle (P) and a rotation angle formed in the middle of the deceleration at the hammering is detected as DELTA H and accumulated, and a preset design angle Pd for hammering is accumulated. A wobbling angle is calculated from Equation: A wobbling angle = P - a cumulative total of Pd - a cumulative total of DELTA H (where Pd is a design value of the powered wrench, indicating an angle corresponding to 360 DEG /m for the case of the m number of hammerings per rotation of the rotary member). When the cumulative total of the rotation angle DELTA H during the deceleration at the hammering reaches the design angle for hammering Pd, the rotation of the rotary member is stopped. In screw loosening, the rotary member is rotated in the opposite direction, so that when the rotation angle of the rotary member reaches a predetermined number of rotations in the loosening direction similarly, the rotation of the rotary member is stopped. <IMAGE> |
