The Study of the taper-cut machining process of the wire-EDM

• Main Author: 蘇柏全
• Other Authors: YunShien Liao
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/36037718518774892930

碩士 === 國立臺灣大學 === 機械工程學研究所 === 90 === Improvement of the machining performance of the taper-cut machining process of the wire —EDM is studied, in a hope that higher machining speed can be obtained by way of adjusting the tension of the wire. Most of the studies to date regarding the taper-cut machining are aimed at modifying the mechanism of the wire—EDM machines, in an effort to have the upper and lower guides of the wire concentrically aligned so that the machining fluid, i.e. water, can be easily infused into the discharge area to overcome the insufficiency of the flushing of the fluid and therefore a higher machining speed can be applied. However, for the traditional wire-EDM machines of which the structure and mechanism are unlikely to be modified, it is necessary to investigate other possible approaches for reaching higher the machining speed. In this study, a stand-alone electronic system for discriminating the discharge pulses into two categories — short and normal sparks - is devised in the first place. The percentage of the short sparks against the total discharge pulses, also known as the “short ratio”, is introduced as an index of the machining performance. The lower short ratio implies the more favorable performance. Based on the analysis of pulse trains under various machining conditions involving different wire tensions, water flushing pressures, work piece thickness, the rule for adjusting the tension of the wire in order to have favorable machining speed, in accordance with different inclining angles of wire, is obtained. In addition, a regression equation in which the wire tension, the wire angle, the work feed rate and off time are set as the four variables while the short ratio as the dependent, is established. With the assistance of the equation, short ratio, can be estimated under any given values of the three variables, without the need of the discharge pulses discriminating system said above. In the end, this paper also proposes a control strategy for taper-cut machining process of wire-EDM so as to develop a real-time on-line discharge pulses monitoring system.