| 摘要 |
TENSION CONTROL OF FASTENERS There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle advance, final tension rate relative to angle advance and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle of advance are monitored during the tightening of production fasteners. Calculations are conducted, while tightening, of the ratio of the torque and the torque rate of the fastener being tightened to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fasteners is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique is also used merely to monitor tightening which is terminated by a different tightening strategy. In another embodiment, analog devices are utilized to convert sensed values of torque and the rate of threading advance into parameters which control tool shut off. |
