Constant Speed And Tension Control Of Wire Electrode For LS-WEDM

Tension control is an important compositive tache of many process, and is one of the important targets to evaluate the performance of WEDM-LS(Low Speed Wire Electrical Discharge Machining). It is one of the important reasons to cause the deterioration of the machining precision and surface quality. So it has profound meanings to control the velocity and tension to minish vibrations of wire electrode.This article is mainly about the research according to the development of WEDM-LS. The development and application of the constant tension control for electrode wire of the WEDM-LS is summarized, every constant tension control system and constant-extented-force controller are analyzed and researched. On the base of this, the loading performances of magnetic particle brake (MPB) and double- motor are used, a tension control with tension feedback which belongs to direct tension control pattern of wire-feeding system is put forward with PC as main control unit which can carry out modified incremental digital PID algorithm, the tension sensor which can detect the tension as the feedback unit, the data collector card based on PCI bus as converting I/O module. This method realizes the whole negative feedback control loop. And then, the controller modeling is simulated with Matlab/Simulink after the maths model of wire-feeding system is set up and a system transforming function is presented. The feasibility of this project is advisable.According to theses theoretical basis, the multi-circuits with constant voltage and constant current source circuit are designed and the software containing the D/A converting, the digital filter, the rotating speed tester and constant tension control. Also, a real time controlling of wire-feeding system is realized, so that the feasible and stability of the wire-feeding system is assured.Through experimental studies, the control performance standards, such as overshoot, fluctuation rate, transient time, are analyzed. The responsive velocity of the loading performances of double-motor is higher than the loading performances of magnetic particle brake after comparison. And the comparison wave of tension for electrode wire of two schemes designed in this article with Mitsubishi RA9 WEDM-LS and WEDM-LS produced by Suzhou EDM research institute, shows that this wire-feeding system has good stability and feasibility and the control strategy is confirmed.