| 摘要 |
Apparatus and method for determining dynamic friction in a threaded joint and an associated tightening system for tightening such joints including threaded fasteners. A value representative of the coefficient of friction in the threaded joint is obtained by determining the gradient of a torque-rotation curve which could be plotted for the joint being tightened, and dividing this gradient by the product of the fastener pitch diameter and the tension rate of the joint. The desired tightened condition is achieved by computing the tightening torque required to induce a predetermined preload in the threaded fastener and comparing this computed torque with the instantaneous torque being imparted to the fastener. When the two torques are equal, tightening of the fastener is stopped. The desired tightening torque may be computed by obtaining the product of the value representative of the coefficient of friction, the predetermined preload and the pitch diameter of the fastener, or alternatively, by obtaining the product of the gradient of the torque-rotation curve and the quotient of the predetermined preload divided by the tension rate of the joint.
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