Machining Error Compensation System in End Milling (1^st Report)

—Machining error prediction and NC data modification in ball end milling based on dynamic deflection model—

Abstract

A machining error compensation system caused by dynamic deflection and shape error of ball end mill was developed. Tool deflection is predicted by instantaneous rigid cutting force and dynamic deflection model with FFT algorithm. Tool shape error is estimated by measuring the diameter of tool during rotating. Machining error is predicted from the tool deflection when cutting edge generates finished surface and the shape error of the edge. The finished surface is detected by rendering image with GPU in short time. NC data generated with CAM software is modified based on the result of error prediction. The system was verified with cutting experiments of cylindrical surface and die model. In the former case, it was shown that the predicted cutting forces, tool deflections, and machining errors were in good agreement with the measured ones, and the maximum machining error decreased from 25.2μm to 7.3μm. In the latter case, machining error was predicted at each tool position about 0.05 second.