Case Studies

 A typical practical application of AC is in profile or contour milling jobs on a numerical control machine using feed as the controlled variable,and spidle deflection(to measure force) or horsepower,or both,as measured variables. It is common to attach an adaptive controller to an NC machine tool. Numerical control machines are a natural starting point for AC because of two reasons. First NC, machine tools possess the required servomotors on the tables axes to accept automatic control.  Second the usual kinds of machining jobs for which NC is used possess the sources of variablility that make AC feasible.  Several large companies have retrofitted their NC machines to incorporate the AC capabilities. In fact one company called Macotech corparation in seattle specializes in retrofitting for other companies.
     The control strategy is of the ACC type rather ACO type:contraint limits are established for the measured process variable
For example if cutter delection is measured variable then the value of  maximum spindle deflection which the particular cutter can withstand is calculated  . This value becomes the operating level of spindle deflection.  Figure below shows a shematic diagram of the adaptive control machining system It operates on the principle of maintaining a contant cutter force during the machining operation . When the force increases due tio increased workpiece hardness or depth or width of cut  the feed rate is reduced to compensate. When the forces decrease owing to decreases in the foregoing variables or air gaps in the part feed rate is increased to maximize the rate of metal removal.