Research on Measuring Accuracy Improvement for Tool Presetter

Tool presetter is a type of precision measuring instrument that associates to CNC machine tools and machining centers, which integrates the technologies of optics, mechanics and electrics all together, and its measuring accuracy gives direct influence on machining accuracy of CNC machines. The main factors that influence measuring accuracy of tool presetter include: image edge detection, image positioning and accuracy of its mechanical system. This paper gives analysis on these main factors and puts forward three newly developed algorithms for improving measuring accuracy of tool presetter. First algorithm is image edge detection algorithm based on subpixel that increases the edge positioning accuracy by more than 10 times. Second one is uniformity compensation algorithm for whole view measurement that is able to capture accurate real pixel size so that image movement is more precise, which further increases the measuring accuracy. The third one is linear compensation algorithm in the measuring space that makes effective compensation to the mechanical system errors, which can compensate any position in measurement space so that system accuracy increases significantly. These algorithms are tested in CoVis software and the results show that the total measuring accuracy of tool presetter is improved dramtically to 2 μm.