Prediction of Thread Quality by Detection and Estimation of Tapping Faults

Abstract

A method is proposed for predicting the internal thread height as a function of tapping process faults and relating it to the standardized thread quality tolerances. Based on the mechanistic tapping model [6], a method of estimating the magnitudes of the faults has been proposed. The effects of tap-hole axes misalignment and tap runout on thread height have been revealed by the mechanistic tapping process model. Based on this model and data obtained from the process estimated process fault values have been used to predict thread height and then predict thread pitch diameter. Using standard tolerances for pitch diameter, an assessment of thread quality can then be made. Validation experiments have been run on several materials for different combinations of process faults. Results of thread measurements showed excellent correspondence with the model predictions.

Experimental investigation of ultrasonic vibration-assisted tapping

“…They claimed that the model is able to predict the thread height and pitch size of the tapped hole with an accuracy of within 2% of the actual measured values of the finished pieces [12]. An oblique cutting model proposed by Dogra et al is capable of calculating the cutting force for taps of different geometrical shapes and inner holes of different features.…”

Investigation on Tool Deflection During Tapping

“…They use a mechanistic model approach to predict the effect of axis offset, tool runout and synchronization errors on the resulting torque and forces. Mezentsev et al [16,17] describe the effect of axis offset and tool runout on tapping, with focus on the resulting radial forces and the thread geometry. The thread geometry is therein defined by the nominal diameter D, the core diameter D 1 and the pitch diameter D 2 (see Fig.…”

Thread Quality Control in High-Speed Tapping Cycles

“…Thread quality has not been studied in the literature because the gauges guaranteed this quality. However, Mezentsev et al [3] proposed a thread quality predicting method which estimates some faults like tap-hole axes misalignment and tap runout on the screw height. Currently, there is more investigation analyzing the thread quality.…”