Constant turning force operation with a fixed metal removal rate via a prior fuzzy controller system

This study examines constant metal removal rate (MRR) with constant turning force (CTF) that operates by means of a prior fuzzy controller (PFC) that is able to automatically manipulate the spindle speed to maintain the MRR at a specified suitable value. Fuzzy-control techniques and grey theory are integrated to integrate a PFC into the constant turning force operation. The most important difference between the PFC and conventional fuzzy controller (FC) is that the fuzzy control signal is determined by the future predicted-state value obtained by a grey model instead of by the present-state value used in the traditional fuzzy controller (FC). Hence, the control signal can be obtained in advance and ensure the safety of the system. This study adopts an auxiliary fixed metal removal rate (MRR) controller, which can respond to the lathe power, machining roughness or tool chatter, and which in constant turning force (CTF) operations is adopted because when the controlled system is a non-linear function, as F-c = aK(f)f(p), the productivity will always decrease. With the exponential function, the increase in cutting depth a will entail decrease in the feed f, thus reducing the metal removal rate (MRR), which is defined as MRR = afV(c) (mm(3) s(-1)). A suitable solution is to increase the cutting speed V-c (mm s(-1)). Consequently, the concept of the MRR is built into the auxiliary controller to improve the CTF control system. (C) 1997 Elsevier Science S.A.