In‐process measurements of wall thickness deviations during turning

Abstract

During the turning process of a ring, the clamping force of the chuck causes circumferential deviations in the ring wall thickness and diameter. This paper focuses on an ultrasonic in-process measuring system which is a prerequisite for in-process compensation of the wall thickness deviation during turning using a fast tool servo. The presented system is coupled to the ring via a cooling lubricant jet and determines the phase difference between the echoes of an ultrasound burst, which are reflected from the outer and the inner ring surface. In order to ensure an accurate operation of the system in a turning centre, the influences of different operating conditions on the signal quality (amplitude height and variation, uncertainty of phase determination) were examined. The wall thickness measurement results of the ultrasonic system were compared with reference data from a coordinate measuring machine. As the observed differences between both methods are sufficiently small, the ultrasonic system is applicable to the in-process compensation of wall thickness deviations in a turning process.

Calibration routine for in-process roundness measurements of steel rings during heat treatment

“…During cutting a FastTool Servo (FTS) was implemented to perform fast variation of cutting depth [1]. By means of in-process-measurement data with an ultrasonic sensor and a closed loop control, the FTS is able to compensate wall thickness deviation [2,3]. In the following sub-processes, a furnace [4] and a gas nozzle field [5] are specially designed with the ability to respectively heat and quench a ring symmetrically or asymmetrically.…”