| 摘要 |
A self-contained impact wrench having an adaptive control system for determining the yield point or some similarly significant tightened condition of a fastener assembly by detecting a signal representative of the forward rotation angle of the fastener assembly is disclosed. One embodiment utilizes a computed signal of time over a fixed interval of forward rotation angle, as an estimate of the torque applied by the impact wrench, and the torque estimate vs. rotation angle curve is differentiated to obtain the gradient thereof. Successive gradient values are stored and compared, and when the present gradient value has attained a predetermined relationship relative to a stored value of a gradient in a tightening region of the curve, further tightening of the fastener assembly is discontinued. This ensures that the yield point or other similarly significant tightened condition of the assembly has been reached. |
