On-line Thickness Measurement System for the Metal Spinning Process

Abstract

Spun-part wall thickness is a key output parameter of spinning products. Thickness affects the spun part strength: Low thickness leads to cracks on spinning products. Hence, it is crucial to measure and control wall thickness. However, thickness measurement and a control system for the spinning process are still offline methods. That is, these parameters must be measured after the spinning process is completed. In this method, the cross section of the spun part is cut, and the wall thickness is measured using a measurement tool. Thus, the measurement system is not applicable as online method. Hence, this study proposed the online thickness measurement method for the spun. Here, the mandrel-less spinning machine and a line laser measurement system were developed. The line laser measurement system, including two sets of line lasers and cameras, was attached on the spinning machine. Both sets of line lasers and cameras were used to measure the thickness profile of the spun part. The first set of a line laser and camera was used to capture the surface profile in the front of the spun part, while the other set was used to capture the surface profile behind the part. Then, the digital image processing (DIP) was estimated the spun thickness by using both images. In the experiments, the spun part was formed by the variation of degrees of angle and spinning distance. In each experiment, the spun-part thickness was measured by the cross-section method and line laser measurement method. Both results were compared and discussed. The result revealed that the thickness estimated by the line laser measurement system is similar to that estimated by the cross-section measurement method. An average error of 3.67% was obtained by the line laser measurement system.