| Wire Electrical Discharge Machining (WEDM) has been widely used in mould manufacturing, shaped cutters processing, and machining of difficult-to-cut materials and precise complicated parts. Nowadays the developing trends of WEDM are precise-microlization, intellectualization, individualization, environmental protection and high efficiency. Dry WEDM is a newly developed technology, which has the features of better surface straightness, smaller gap, no electrochemical corrosion and no pollution in comparing with the traditional WEDM. So this new method is suitable for WEDM finishing.This paper summarized the theory of high-speed WEDM (HS-WEDM). The basic forms of conductance and breakdown in dielectric, discharge voltage characteristic between electrodes, and the discharge voltage comparison of WEDM finishing in gas and liquid were also introduced. Moreover, the multiple cut process in WEDM, the HS-WEDM machine used in experiments and surface contour measuring machine were briefly introduced.Typical mould steel Cr12MoV was selected as testpiece material .in the Gas-liquid Combined Multiple Cut test. Firstly, roughing tests were done in emulsion liquid. And the affections of peak current and pulse duration on surface roughness and cutting speed were studied. The second cut (semi-finishing) was processed in atmosphere, in which the influence of wire length was studied and the selection of other parameters were introduced. Orthogonal test with L16(45) design were done in the second cut, and significant order influencing roughness and removal rate were found.The movement modle of the four-axle linkage system was established and simulation was developed using the Programming language Visual C++6.0 and standard connection for three dimensional graph software OpenGL. An additional numerical control (NC) worktable (rotation-swing-swing worktable) for complex curved surface processing and its NC system were designed. |
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