Fractal Analysis of Grain Cutting Edge Wear in Superabrasive Grinding
This paper deals with a fractal analysis of the wear behavior of the grain cutting edges in superabrasive grinding. Fundamental overcut fly grinding experiments for producing individual straight grooves using a grinding tool with multiple grits are carried out to clarify the wear characteristics of the grain cutting edges in the grinding process and then the change in three-dimensional profile of the cutting edge measured with a multiprobe SEM is evaluated on the basis of fractal analysis. The main results are summarized as follows: (1) Fractal dimension for the contour line of the fine cutting edge formed by micro fracture shows a higher value than that of cutting edge formed by attritious wear or large fracture. (2) Fractal dimension for cBN grain cutting edge mainly formed by micro fracture tends to take a higher value than that for diamond grain cutting edge mainly formed by attritious wear. (3) The complex change in shape of the cutting edge with the progress of grinding process can be quantitatively evaluated by means of fractal analysis.
Investigation of diamond wheel topography in Elliptical Ultrasonic Assisted Grinding (EUAG) of monocrystal sapphire using fractal analysis method
HighlightsThe fractal dimension of wheel topography is highly correlated to wear mechanisms.An increase in cutting edge density results in an increase of fractal dimension.The fractal dimension decreases as the grain pullout and wheel loading increase.Wheel topography changes from isotropic to anisotropic as grinding passes increase. ABSTRACT The wear behaviors of grinding wheel have significant influence on the work‐surface topography. However, a comprehensive and quantitative method is lacking for evaluating the wear conditions of grinding wheel. In this paper, a fractal analysis method is used to investigate the wear behavior of resin‐bonded diamond wheel in Elliptical Ultrasonic Assisted Grinding (EUAG) of monocrystal sapphire, and a series of experiments on EUAG and conventional grinding (CG) are performed. The results show that the fractal dimension of grinding wheel topography is highly correlated to the wear behavior, i.e., grain fracture, grain pullout, and wheel loading. An increase in cutting edge density on the wheel surface results in an increase of the fractal dimension, but an increase in the grain pullout and wheel loading results in a decrease in the fractal dimension. The wheel topography in EUAG has a higher fractal dimension than that in CG before 60 passes due to better self‐sharpening behavior, and then has a smaller fractal dimension because of more serious wheel loadings after 60 passes. By angle‐dependent distribution analysis of profile fractal dimensions, the wheel surface topography is transformed from isotropic to anisotropic. These indicated that the fractal analysis method could be further used in monitoring of a grinding wheel performance in EUAG.
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.