#$NPMechanism of Electrostatic Atomization and Surface Quality Evaluation of 7075 Aluminum Alloy under Electrostatic Minimum Quantity Lubrication Milling

WU Xi-feng, XU Wen-hao, MA Hao, ZHOU Zong-ming, LIU Bo, CUI Xin, LI Chang-he

Surface Technology ›› 2023, Vol. 52 ›› Issue (6) : 337-350.

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Surface Technology ›› 2023, Vol. 52 ›› Issue (6) : 337-350. DOI: 10.16490/j.cnki.issn.1001-3660.2023.06.030

#$NPMechanism of Electrostatic Atomization and Surface Quality Evaluation of 7075 Aluminum Alloy under Electrostatic Minimum Quantity Lubrication Milling

  • WU Xi-feng1, XU Wen-hao1, MA Hao1, CUI Xin1, LI Chang-he1, ZHOU Zong-ming2, LIU Bo3
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Abstract

In order to solve the technical problems of poor atomization performance, high environmental aerosol concentration and poor parameterization controllability of traditional pneumatic atomization minimum quantity lubrication milling, an electrostatic atomization minimum quantity lubrication milling supply system has been designed. The work aims to study the airflow field at the constrained interface of tool-workpiece, analyze the mechanism of electrostatic minimum quantity lubrication (EMQL) and evaluate the milling surface quality of 7075 aluminum alloy. The airflow field distribution at the constrained interface of the tool-workpiece was analyzed to theoretically model the velocity distribution of the vortex in the airflow field. The optimal jet position of the nozzle was established based on the kinetic characteristics of the circumferential vortex and the incoming vortex. Then, the charging and atomization mechanism of EMQL were studied. On this basis, milling experiments were carried out to 7075 aluminum alloy under different lubrication conditions, including dry, flood and EMQL. Milling force and milling surface roughness (Ra, Rsm) under the different lubrication conditions were measured. In addition, autocorrelation analysis of the machined surface profiles obtained by EMQL under both parameter conditions was performed. Finally, the mechanism of the charged lubricant in the cutting zone was analyzed. Under the experimental milling parameters, when the induced radius was 0.007 m, the optimal position parameters were set to lz=9.7 mm (distance from the jet point to the workpiece surface), ly=11.5 mm (distance from the jet point to the edge of the milling too) and γ≈40° (included angle between the nozzle and the workpiece in the horizontal direction). Compared with dry milling, EMQL could reduce milling force by 15% and 18.6%. In addition, compared with dry milling, the Ra and Rsmobtained by EMQL under the condition of 30 kV decreased by 15.5% and 25% respectively. Compared with that at 20 kV, the autocorrelation analysis curve of the surface profile of EMQL milling at 30 kV showed better surface quality. The best surface quality (Ra=0.221 μm, Rsm=0.037 μm) was obtained under flood lubrication. The charged droplets can enhance the capillary penetration performance at friction interface and the capillary penetration length can be increased under the condition of increasing voltage. EMQL under high voltage shows better milling performance than that under low voltage.

Key words

milling; electrostatic atomization minimum quantity lubrication; 7075 aluminum alloy; airflow field; nozzle position; surface quality

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WU Xi-feng, XU Wen-hao, MA Hao, ZHOU Zong-ming, LIU Bo, CUI Xin, LI Chang-he. #$NPMechanism of Electrostatic Atomization and Surface Quality Evaluation of 7075 Aluminum Alloy under Electrostatic Minimum Quantity Lubrication Milling[J]. Surface Technology. 2023, 52(6): 337-350
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