| Summary: | 碩士 === 南台科技大學 === 奈米科技研究所 === 99 === In this study, the Micro-WEDM machine is used to research how the corner cutting process in accuracy. The dielectric was de-ionized (DI) water, the diameter of wolfram wire selected was 30μm. The material is Stainless Steel SUS420 after heat treatment. The discharging parameter thickness and the workpiece thickness were the same as 6mm. From the input conditions, the smart program inside the machine automatically outputted working parameters to process: flushing pressure (P) is 1.2 (bar), wire tension(FW) is 0.8 (N), and wire speed (AW) is 75 (mm/s). In this study, to compared with the
automatically working parameters outputted from the machine, the working parameters was adjusted to: flushing pressure (P) is 0.3、0.7、1.2、2、2.5 (bar), wire tension (FW) is 0.5、0.8、1.1、1.5 (N), and wire speed (AW) is 75、120 (mm/s) control strategy, processing six times with 30、60、90 degree V-cut grooves to observe the corner cutting shape, material removal rate, surface roughness, surface morphology.
The results showed that the variation of the corner cutting shape is mainly affected by wire tension and flushing pressure, but the wire tension has the largest effect. The corner cutting shape was changed about 17μm when the wire tension adjustment was at 0.5N (minimum) and 1.5N (maximum). Material removal rate in the flushing pressure (P), wire tension (FW) and wire speed (AW) have no significant effect. The surface roughness can be better when increased the processing time, flushing pressure (P) and wire tension (FW), the best surface roughness (Ra) was found that is about 0.22μm.
The adjustment of processing parameters cutting 30、60、90 degree V-cut grooves, as the flushing pressure is too low is not easy to remove machining debris in the processing of the tooth tip is easy to produce secondary discharge, and high flushing pressure is easy to shift and sway caused by wire within the fillet diameter of the
expansion, so the more focus on plane and the tooth tip distance and height part, the choice of flushing pressure 2 bar better, but for this part of the fillet diameter of the flushing pressure 0.7bar use more appropriate. Wire tension with continuous line of maximum tension 1.5N better. The wire speed (AW) almost has no significant effect, so the best selection of machine parameters of 75 mm/s. Three kinds of angles need to adjust the best parameters of the trend is the same, but with increasing angle the greater the improvement of machining accuracy.
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