PRAKTISK BESTÄMNING AV KLÄMKRAFT OCH FRIKTION I SKRUVFÖRBAND
This report reflects an examination work performed for Getrag All Wheel Drive AB during the spring of 2005. Among the companies range of products there exists some concern regarding the amount of clamping force and friction on bolted joints caused by the assembly torque.The aim of this project has been to determine if there is a simple way in which to identify and then practically apply testing methods for clamping force and friction through utilization of existing testing equipment.Three separate methods of clamping force and friction determination have been tested in rear drive unit, RDU, at a 30 Nm assembly torque. A fourth and final method, screw elongation with ultrasound, has been used as reference. The methods are:?Torque-Tension test.?Screw elongation with micrometer.?Joint stiffness test.?Screw elongation with ultra sound for reference.The results from tests can be viewed in table below.MethodTorque-TensionMicrometerCs=318 kN/mm Assembled with torque wrenchMicrometerCs=318 kN/mm Assembled on lineUltra-soundCS=311 kN/mm Ultra- soundCS=318 kN/mm Joint stiffnessTheoreticalClamping force-21,8 kN17,6 kN17,3 kN17,6 kN17,1 kN17,3 kNFriction-0,110,1470,1530,1470,1520,149