|
CSME 2020/12
Volume 41 No.6
:
763-772
|
|
Study on the Application of Electrode Control Aided Electrochemical Discharge Drilling Method in Transparent Brittle Materials
Chao-Ching Hoa and Yu-An Linb
aGraduate Institute of Manufacturing Technology and Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan 10608, ROC.
bGraduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei, Taiwan 10608, ROC.
|
Abstract:
The Electrochemical Discharge Machining is a kind of innovative machining method newly developed for processing the non-conductive brittle materials. To enhance the machining efficiency and optimize the drilling depth, normally the voltage or the electrolyte concentration increasing method is applied. However, excessively high voltage and electrolyte concentration are the main reasons causing the over-cutting, heat-affected area expansion and cavities as to degrade the quality. Therefore, the graphic and current monitoring approaches are used in the online-aided machining system during the research to achieve the parameter-based real-time feedback and adjustment effect. To support the glazing system, the cumulative extent of bubbles and the electrode features are observed to determine the appropriate timing for performing the polarity switching; further, the current values are also controlled to minimize the glass shattering effect when passing through the conveying hole. The polarity switching result indicated that this research can reduce 22.84% of front-side cavity overcut and 36.73% of through-hole overcut. In heat-affected area, 41.99% can be reduced for part of front-side heat-affected area; whereas, 24.4% can be reduced for the through-hole heat-affected area. Regarding the sapphire machining, the current-responsive inching control method was applied that the electrolyte at the electrolyte tip can be renewed as to minimize the influence resulting from electrolyte degradation while limiting the discharge of current. In view of this, the machining work can be performed under higher level of voltage without damaging the electrode. Furthermore, multiple pieces of electrodes are also used in this research for easier replacement as to stabilize the electrode material. Finally, during the composite control aided machining, we have achieved 184.06 μm maximum depth which represents 61.67% more of drilling depth when compared to the uncontrolled machining result.
|
|
Keywords: electrochemical discharge machining, transparent hard and brittle material, Polarity reverse machining, digital image processing.
|
Download PDF
|
|
*Corresponding author; e-mail:
|
©
2020
CSME , ISSN 0257-9731
|