Research On The Cutting Accuracy And Surface Quality Of Multi-cutting In HSWEDM

HSWEDM has been widely used in mechanical manufacturing field because of its high cost performance and low running cost, but the unstable cutting accuracy and poor surface qulity constrain the development of this technology and affect its application in the finishing area. Some problems should be considered in HSWEDM multi-cutting: Firstly, gap discharge or not is a key issue which has a direct impact on the stable cutting accuracy. Secondly, the relationship between actual composition and theoretical composition, which has a direct impact on the dimension precision. Thirdly, The electrolyte exist in the composite cooling liquid inevitably, electrolytic corrosion layer exists in the multi-cutting surface because of electrolysis during the discharge process, which may decrease the life of the product. Lastly, The surface roughness of multi-cutting does not improved largly, which has a great gap to the LSWEDM. To address these issues, The main contents of this paper are as follows:1) Discharge mechanism of HSWEDM in composite cooling liquid has been researched. Theoretical analysis and experimental results show that discharge process does not produce passive film, electrode wire and workpiece discharge in the gap, which is the basis for follow-up study.2) The rule of the actual compensation's influence factors in HSWEDM multi-cutting by using composite cooling liquid is studied, some factors include electrical parameters such as pulse width, machining current and non-electrical parameters such as wire between guide distance, actual feed speed, wire traveling speed, which have great influence on the actual compensation while the pulse interval and wire tension have no obvious effect on the actual compensation. The experiments results indicate that the actual composition is identical with the theoretical composition after considering the difference of discharge gap between first cutting and last ones.3) Thermo-analysis was carried out in the last cutting of multi-cutting to analyze the maximum depth of discharge crater, and then indicate the optimum surface roughness which can obtain in the multi-cutting surface in HSWEDM. Comparing the simulation result with experiment result, the simulation result plays a guiding role to the improvement of technique.4) Multi-cutting's surface quality has been researched. Proposed the reversed polarity machining method to avoid the electrolytic corrosion layer. New methods that reversed polarity machining by using non-ion kerosene or compressed air as working medium in the last cutting have been carried out, which enable to reduce pulse energy of the last cutting to obtain low surface roughness.