Close-to-process strain measurement in ultrasonic vibration-assisted turning

Abstract

Abstract. The application of ultrasonic vibration assistance in machining offers many benefits over conventional machining. In some machining processes, like the generation of geometrically defined microstructures by cutting, the interaction of the system components and the machining process can be particularly crucial with respect to the production result. Monitoring of ultrasonic vibration-assisted machining in terms of the in-process measurement of frequency and amplitude is currently realized by measurement inside the actuator; thus, measurement is presently undertaken relatively far away from the cutting process. In this paper an in-process measurement set-up based on strain gauges positioned close to the cutting edges is presented. It is used to investigate the induced vibration in the ultrasonic horn. Experiments on machine samples with and without ultrasonic vibration assistance are performed using the in-process measurement set-up described. The results of the strain gauges are analysed in comparison to internal feedback signal and surface measurements. The experiments show the high sensitivity of the measurement set-up presented and a huge gain of information compared with the conventional measurement approach. This enables improved controllability of the excited mode shapes as well as in-process adjustment of the ultrasonic vibration frequency and amplitude for the manufacturing of defined microstructures.

Feasibility Study for Monitoring an Ultrasonic System Using Structurally Integrated Piezoceramics

“…Previous work conducted by the authors investigated using strain gauges for monitoring an ultrasonic-assisted turning process. The results showed that using strain gauges enables the detection of the current vibration shape of the system and allows for in-process measurement of ultrasonic systems, which may be used in control systems in the future [17]. The ultrasonic system used by Kimme et al also included an additional piezoelectric disc in the transducer to monitor the vibration and control the excitation frequency.…”

Investigation of an indirect measurement method of ultrasonic bone cutting forces based on strain sensors

“…Khambay et al [20,21] measured the cutting force during ultrasonic chisel cutting of bovine bone using a strain gauge and studied the relationship between the cutting force and the tool rake angle and cutting speed. Kimme et al [22] proposed a strain gauge based on the position close to the cutting edge to measure the induced strain of an ultrasonic horn, and pointed out that multiple measurement positions on the ultrasonic horn can also estimate cutting force and current modal shape. This provides a new approach and direction for ultrasonic cutting force measurement, while also raising requirements for measurement accuracy and reliability.…”