In an effort to reduce machining surface errors due to tool deflection in the end milling process, methods regulating cutting forces have been implemented with on-line feed rate controls. Such schemes are able to improve the parts dimensional accuracy, but unfortunately they can exhibit undesirable aspects in which the alleviation of the cutting conditions deteriorates the productivity. In addition the frequent changes of the feed rate would spoil the surface quality.
As a new approach to achieve the precision machining efficiently, this paper introduces a tool deflection compensation system. This compensation system is a computer controlled special tool adapter which is capable of measuring the cutting forces and minutely adjusting the position of the tool without interfacing with the NC controller of the milling machine. Such a system allows for on-line estimation of the tool deflections and reduction of the surface errors.
In order to obtain the surface error in process, two algorithms are suggested; One is a heuristic approach which can extract the surface error using the magnitude and the fluctuation of the cutting force. The other is an analytical approach which can estimate the surface error and the axial depth of cut analyzing the cutting force pattern. Especially, the estimation algorithm for the axial depth of cut is available for the tool monitoring system as well as the adaptive control system.
Experimental investigations for typical shaped workpieces representing various end milling situations are performed to verify the ability of the system to suppress the surface errors due to tool deflections in more productive machining condition.
