EINRICHTUNG UND VERFAHREN ZUR BESTIMMUNG UND ANZEIGE DES DREHMOMENTES AN DRUCKMITTELBETRIEBENEN SCHRAUBWINDEN SOWIE ZUR AUTOMATISCHEN BETAETIGUNG UND BEENDIGUNG DER BETAETIGUNG SOLCHER SCHRAUBWINDEN

摘要

A fluid powered torque wrench 10 is automatically operated until a preset torque has been delivered to a fastening. As shown, the preset torque is inputted to a computer 114 from a keyboard 116. Computer 114 communicates with a microprocessor 30 which closes a relay 110 to advance the wrench. Fluid pressure is monitored by a transducer 26 and the data is fed from the microprocessor 30 to the computer 114 which determines therefrom whether the preset torque has been reached or whether the wrench has merely completed its advance stroke. By operating relays 110 and 112 the computer retracts the wrench, advances it once more and repeats the cycle until the preset value is reached. The system provides a direct read-out of torque on a display 25A or 118. Also described is a method comprising determining from the pressure data, the nut factor of the fastening being tightened in order to enable determination of the torque needed to obtain a desired preload. <IMAGE>