Compensation Method for Tool Setting Errors Based on Non-Contact On-Machine Measurement

Abstract

The high-accuracy manufacturing of optical requires highly integrated ultraprecision cutting technologies. However, all sorts of small errors adversely affect machining accuracy because of the miniaturization and complexity of objects. Among these errors, slight setting errors critically impact machining accuracy because it is difficult to place a cutting tool accurately on a ultraprecision machine tool. The authors have conducted multi-axis control ultraprecision cutting based on tool setting errors compensation. In this compensation method, the workpiece must be removed from the machine tool after test cutting to measure grooves to detect actual tool positions and to calculate setting errors. However, after the workpiece is removed, it cannot be perfectly replaced on a ultraprecision machine tool. This makes it difficult to automate setting errors compensation. In order to solve these problems, tool positioning must be detected without removing the workpiece. Therefore, in this study, a novel compensation method is developed by means of non-contact measurement with a laser imaging device. Furthermore, in order to improve compensation performance, a laser imaging device is calibrated on an ultraprecision machine tool. The proposed method enables direct detection of actual tool position and calculation of the tool centerpoint coordinate on the machine coordinate system. By modifying an NC program, the tool setting errors can be finally compensated. The feasibility of the proposed compensation method is verified by conducting experiments of creating grooves.