| Summary: | 碩士 === 崑山科技大學 === 機械工程研究所 === 93 === Electrical-discharge machining offen tends to induce roughness and the transformation layer on the machined surface, and induces negative effects to tool steel dies. Subsequent operations are required to clear them off. The study with the purpose of tool steel grade SKD11 to be experimented on the micro-hole electrical-discharge machining to analyze the surface roughness, hole enlargement and the transformation layer resulting from EDM process.
The experiment consists of two steps in this paper. The first step is to use Taguchi method L9 orthogonal array to obtain those primary EDM parameters affecting the material removal rate, the relative electrode wear ratio, the surface roughness, the hole enlargement and the thickness of the transformation layer, and to get the optimal parameters group. The next step is to conduct full factorial experiments and regression analysis with the primary effective parameters to understand the trend of the effect and relation between the parameters and the material removal rate, the surface roughness, the hole enlargement, and the thickness of the transformation layer.
By the deviation analysis of Taguchi method, we find pulse-on duration are the primary influencing parameters for the material removal rate, the secondary parameters is the pulse current. The primary influencing parameters for the relative electrode wear ratio are pulse-on duration, the secondary are the pulse current. The primary influencing parameters for the surface roughness are the pulse current, the secondary is pulse-on duration. The primary influencing parameters for the hole enlargement are pulse-on duration, the secondary are the pulse current. The influencing effective parameters for the thickness of the transformation layer are pulse-on duration, the secondary is pulse current. From the full factorial experiment shows the material removal rate, the surface roughness, the hole enlargement and the thickness of the transformation layer, increase as the pulse-on duration and the pulse current increase. The next step is to conduct regression analysis to obtain the formula of experience for the material removal rate is MRR=0.000008(Ip0.81×Ton1.2). The formula of experience for the surface roughness is SR=0.0813(Ip0.59×Ton0.36). The formula of experience for the hole enlargement is HE=0.0045(Ip0.7×Ton0.3). The formula of experience for the thickness of the transformation layer is WLT=8.95(Ip0.05×Ton0.2).
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