Test Rig Development for Real Time Clamping Force Estimation in Threaded Tightenings with Implemented Extended Kalman Filtering

Abstract: The clamping force between the components during bolt tightening is of great interest, and it has been the focus of developing new tightening techniques for a long time. Today there is no easy or practical method to directly measure the clamping force in a typical production situation. However, if the clamping force could be estimated while performing the tightening, it would be precious since it gives information on whether the joint can carry the load between the components. This master thesis aimed to build a test rig for estimating clamping force in real-time during bolt tightening with Kalman filtering, modelled from the bolt formula Kellerman-Klein equation. This thesis was a continuation of a previous master’s thesis, which developed the algorithm in an offline environment. The focus of designing the test rig was to investigate where in the drive line placing the IRTT inline rotary torque transducer would give the best clamping force estimation compared to the measured clamping force with a force sensor. The result showed that the placement of the IRTT sensor did not substantially impact the clamping force estimation. The best mean quality value of the estimation of 75,23% was achieved when the IRTT sensor had a placement between the motor and the gearbox. The result of the thesis was a new physical platform for estimating clamping force in real time.