The adaptive control of tool force during roughing operations in continuous metal cutting

Sadek, Hassan Ramadan Mohammed (1990) The adaptive control of tool force during roughing operations in continuous metal cutting. University of Southampton, Doctoral Thesis.

Abstract

The goal of the application of adaptive control to machine tools is to achieve high production rates even though the machining parameters change due to load, workpiece and tool conditions. The theoretical development of adaptive control is however, far ahead of its applications, particularly in manufacturing. This is mainly because of the inertia of the capital invested in traditional manufacturing systems. Successful applications of adaptive control will no doubt speed industrial progress and effectiveness through an expected increase in productivity. This thesis begins with an explanation of adaptive control (AC) and its classification into two branches, adaptive control with optimization (ACO) and adaptive control with constraints (ACC) which are interpreted. Research work carried out in the past 30 years involving the problems of traditional numerical controlled machine tools and the attempts and effort induced for AC industrial applications and its justification are explained and discussed. A different approach for system identification and parameter estimate is simulated and tested with various controller design techniques. Different controller design algorithms have been developed for rough cutting operations in turning. The control objective was to maintain the cutting force at a constant value and the feed rate was manipulated accordingly. The proposed algorithm was based on closed loop pole-placement with on-line identification using an on-line estimator to determine any changes in the parameters resulting from the changes in the cutting conditions. The results obtained from simulation showed very good results under noisy disturbances and different dynamic changes. Experimental work has been carried out to validate the proposed controller on a modified Myford lathe and the results obtained agree with simulation results. The importance of tool management including tool wear sensing is explained in the appendix together with the difficulty of having a direct measure of tool wear from a one-point cutting tool as in the lathe. The simulation programs are also given in the appendices.

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