Time-varying process model for intelligent prediction of strain and temperature in micro-turning process

Abstract

Time-varying process models for micro-machining processes are important as they aid in control of machining parameters. In this research, a state-space-based process model for the temperature and strain generated near the cutting edge of the tool tip is identified using system identification approach. Fiber Bragg grating sensors were placed rigidly near the cutting edge of the tool tip in a micro-turning setup. Subsequently, micro-turning operations were carried out on aluminum and mild steel. The computer numerically controlled program was such that the machining parameters (feed velocity, depth of cut and RPM) change with machining time. The time-varying machining parameters act as inputs to the model, and the dynamic values of strain and temperature serve as model output. A state-space model was generated using the experimental data. Subsequently, a Kalman filter was used to intelligently predict the values of strain and temperature at the cutting edge of tool tip in advance using the model parameters identified by state-space modeling. Experimental results confirm that the time-varying model and the Kalman filter proposed in this research are effective in predicting the strain and temperature in advance with high accuracy. The maximum error in prediction of temperature was 0.4 °C, whereas for strain prediction, the maximum error was 0.3µ∈.

Investigations on size-effect dependent strain and temperature in micro turning near to the cutting edge

“…Measurement of tool temperature and strain near to cutting edge in micro turning has been attempted recently using FBG sensors. 11,12 However, variations of these two quantities with size-effect influence (cutting, ploughing and slipping) which is essential for micro turning as opposed to conventional machining operations are not available. In order to bridge the existing gaps in and to analyze the variation of strain and temperature with varying conditions due to size-effect, which could facilitate better tool state monitoring and surface integrity assessment in micro turning, we propose a generic methodology for the same in this research.…”

“…Measurement of tool temperature and strain near to cutting edge in micro turning has been attempted recently using FBG sensors. 11,12 However, variations of these two quantities with size-effect influence (cutting, ploughing and slipping) which is essential for micro turning as opposed to conventional machining operations are not available.…”

Measurement of forces on multi-point forming tools using fibre Bragg grating sensors

“…27 FBG sensors were used to measure strain and temperature induced during micro-turning operations. 28 Force sensitive forceps with an FBG sensor on the grasper were proposed for a surgical robot in a surgery environment. 29 A bolt force status monitoring method using FBG sensors was proposed for remote real-time monitoring of roadway anchorage engineering.…”

“…27 FBG sensors were used to measure strain and temperature induced during micro-turning operations. 28…”