| 摘要 |
PROBLEM TO BE SOLVED: To seat a screw by an accurate axial force by calculating an accurate seating torque or a final torque of the screw in a screw fastening device using an electric screw driver. SOLUTION: This screw fastening device is fitted with the screw in the tip of the electric screw driver, controls the electric screw driver according to prescribed screw fastening control characteristics based on the rotation speed and the running torque of the electric screw driver, and fastens the screw into a prepared hole. The screw 12 is threaded in the prepared hole 18 from starting the rotation of the screw driver. This screw fastening device is so formed that a time when the running torque of the electric screw driver reaches a prescribed value is set to a control start point of the electric screw driver, the seating torque when the screw seats therein is estimated from a change in the running torque of the electric screw driver in time points t1 and t2 in prescribed different times, and the final screw fastening torque Tf after seating the screw is corrected according to the dimension of the estimated seating torque, thus accurately fastening the screw. COPYRIGHT: (C)2003,JPO
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