Error compensation method for milling single-threaded screw rotors with end mill tools

Form milling using end mill tools is commonly employed to manufacture single-threaded screw rotors, especially for profiles where a side mill tool is inapplicable. In practical applications, position deviation and wear of the cutter mainly affect the machining accuracy of screw rotors. Therefore, this study proposes a method to compensate for machining errors through profile correction and position adjustment of the end mill tool for single-threaded screw rotor milling. The milling process is simulated by an established coordinate system of a multi-axis computerised numerical control milling machine. The effect of end mill tool profile and position on the rotor profile deviation can be analysed and collected to form sensitivity matrices. Based on these matrices and the Levenberg–Marquardt algorithm, profile deviation is greatly reduced after several closed-loop iterative compensations. In the presented examples, a fault in an end mill tool profile calculated by the Holroyd Profile Management System is successfully solved. Improvements in rotor profile deviations are investigated by considering different combinations of end mill tool position parameters and by performing end mill tool profile correction.