脉冲电化学光整加工中表面形貌变化试验

Experimental on Surface Micro Morphology of Pulse Electrochemical Finishing

探究脉冲电化学光整(PECF)加工过程中表面形貌变化特性及其工艺能力。在能实现表面良好加工效果的参数范围内,对304不锈钢车削与磨削表面进行脉冲电化学光整加工,通过对加工前后表面微观形貌变化规律的对比分析,研究脉冲电化学光整加工工艺对不同表面的整平能力。试验结果表明:脉冲电化学光整加工车削和磨削表面所能获得的最终表面粗糙度大体相当,加工后两种表面粗糙度Ra、R_(z)和R_(sm)值处于同一量级,分别达到0.09、0.7、50μm左右。表面微观形貌趋于一致,表面完整性良好,表面特征指标不具有显著差异性。脉冲电化学光整加工车削和磨削表面的形貌变化过程有所差别,车削表面存在由原始表面形貌向脉冲电化学光整加工表面形貌转变的一段中间过程,磨削表面形貌则在短时间内迅速转变为脉冲电化学光整加工表面形貌。对原始表面较为粗糙的零件或者难以采用磨削加工的薄壁件,PECF加工是一种具有实际应用价值的加工方式,且对于一些具有特殊要求的功能性表面形貌,车削后进行PECF加工可能成为一种新的加工方法。

The changes in surface morphology and processing ability were investigated during pulse electrochemical finishing(PECF)of 304 stainless steel surfaces.To realize optimal surface finishing effects,the turning and grinding surfaces were processed via PECF.Surface profile images and roughness parameter values were obtained using a probe-type roughness meter.These data were analyzed and summarized to understand the changes in surface topography characteristics during processing.Variance analysis was performed on the surface roughness before and after machining to verify the rules governing surface topography changes during the process.Scanning electron microscope(SEM)and atomic force microscope(AFM)were employed to observe and compare surface micro-morphology before and after processing,confirming the leveling ability of PECF.During machining,height parameters Ra and R_(z)exhibited similar overall change trends,with“inflection points”appearing at 17.5 s and 7.5 s,respectively.The width parameter R_(sm)showed a pattern of initially rising and then falling to varying degrees.A one-factor variance analysis of the roughness parameters of the two surfaces before and after processing revealed that the F values of the roughness parameters Ra,R_(z),R_(sm),Rc,and Rq of the two surfaces before processing were greater than F0.01(1,4)=21.198,indicating that there were significant differences in various roughness indicators between the turning and grinding surfaces.However,after PECF processing,the F values of roughness parameters Ra,R_(z),R_(sm),Rc,and Rq of the two surfaces were less than F0.05(1,4)=7.708,indicating that there were no significant differences in surface roughness indices after the two surfaces were processed via PECF,and the surface topography became more uniform.The post-processing roughness values Ra,R_(z),and R_(sm)for both surfaces were of the same order of magnitude,and they were approximately 0.09μm,0.7μm,and 50μm,respectively.The surfaces displayed good integrity and high quality.PECF led to different morphology changes in the turning and grinding surfaces.There was an intermediate process in the turning surface of the original surface morphology when compared to the surface morphology by PECF,where micro-burrs were leveled while macro-contour undulations retained turning contour characteristics.This finding suggests a potential new method for forming functional surface topographies with specific requirements.Conversely,the grinding surface morphology quickly transformed into the surface morphology by PECF in a short time.By combining SEM and AFM images with the statistical analysis of the surface topography parameters,it can be concluded that turning+PECF processing can realize a similar surface topographic effect as turning+grinding+PECF processing.Direct PECF processing on the turning surface can significantly reduce surface roughness values Ra and R_(z).Through short-duration,single-step processing,the resulting surface roughness range can surpass that obtained by grinding,which is beneficial for shortening the processing cycle and enhancing efficiency.PECF machining is a valuable method for processing parts with rough original surfaces or thin-walled parts that are challenging to grind.PECF after turning can become a new machining approach for functional surface morphologies with specific requirements.