Measurement of Three-dimensional Shape of Minute Burr Formed through Punching Process of Circle Hole.

Formation of minute burr through shearing process brings about some annoying problem relating to post-processing, accuracy of product and worker’s safety and so on. Therefore, restrain or control of burr size and shape is considered as one of the critical issues in shearing process, and so a lot of researches mainly to control burr height have been conducted until now. Previously, our research group had modeled a detailed shape of minute burr, which consisted of burr height, burr root radius, crack angle and die-side angle, and had investigated variations of these parameters using orthogonal four point two-dimensional observation using cut specimen. From these studies, a standard relationship between the way of burr shape formation in a meaning as an average pattern. Then, for deeper understanding of burr shape formation, it was thought that measurement of three-dimensional shape including distribution around the hole should be necessary. Therefore, in this study, three-dimensional measurement of minute burr shape was attempted using a laser microscope. Using a sample of mild steel sheet (SPCC) with a circle hole formed through punching process, angular distribution of a burr shape was measured three-dimensionally. By using laser microscope, height data of the specimen was obtained in orthogonal coordinate. On the bases of this data, noise removal, continuous approximation and coordinate transformation to polar coordinates were conducted. Through these procedures, distribution of three dimensional shape of minute burr could was finally obtained. The usefulness and problems of this measurement were discussed. [ABSTRACT FROM AUTHOR]