Application of fuzzy control for a hydraulic forging machine

Most metal-forming processes are non-linear, non-stationary and time-variant. Nonetheless, linear controllers or LTI-control systems are used for many of these processes. Because of their simplicity of application, fuzzy controllers have recently been implemented for many industrial processes in Europe, in Japan and in the USA. Fuzzy control may be characterized as an approach using controllers which can be designed without a mathematical model of the process and which are inherently non-linear. Fuzzy control is based on a priori expert knowledge which can be described in the form of a language. This paper discusses one application of fuzzy control, an adaptive fuzzy controller for a hydraulic forging machine which minimizes geometrical and material defects of the workpiece by controlling the servo valve and the pump power. The paper describes the use of the fuzzy controller with two processes, upsetting and thixoforging. The design procedure for the controller and experimental results are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.