An approach to real-time compensation of machining error using deflection of tool estimated from cutting forces in end-milling process

抄録

Machining centers have been widely used for metal mold manufacturing processes because high-speed machining using small-diameter end-mills has become practical. However, because the concave portions of the metal molds used for injection molding are very complex and exacting, and also present large differences in depth, long, small-diameter end-mills have to be used for the metal mold manufacturing process. Unfortunately, such end-mills degrade the machining accuracy of the metal mold, because the cutting forces cause the cutting point to deflect considerably. The goal of this study was to improve the real-time compensation for machining errors caused by the deflection of small-diameter end-mills, such as ball end-mills. To achieve this goal, a system of compensating for the machining errors was proposed by using the estimation method obtained from preliminary experiments, and the system validity was verified by performing cutting tests. Cutting tests, in which the axial depth of a cut increased linearly with the cutting duration, were conducted for measuring the cutting forces during the end-milling. As a result, the proposed compensation system could be used for real-time estimation and correction of the machining error caused by end-mill deflection induced by the cutting force. Furthermore, we were able to reduce the machining error by 80% in both down and up cuts, while increasing the axial depth of cuts, by using the proposed compensation system.