Study On Material Removal And Surface Integrity In Ultrosonic Vibration Grinding Of SiCp/Al Composites

Particle reinforced aluminum matrix(SiCp/Al) composites are widely used in aerospace and other fields for their excellent physical properties such as high specific strength and elastic modulus, low density and well high temperature performance. But their processing performance gets bad with the increase of the volume fraction of reinforced particle, so the conventional processing methods are difficult to ensure processing quality. Ultrasonic vibration grinding can reduce the cutting force and improve the cutting efficiency, so it is meaningful to improve the machined surface quality of these materials by investigating the removal process and the evaluation method for composites machined surface topography.This paper analyzed the effect of single grain cutting trajectory and cutting length on material removal process of two kinds of grinding in a period with the established abrasive trajectory equation. It is concluded that ultrasonic vibration can reduce the cutting force and improve the cutting efficiency in the end grinding. For side grinding, ultrasonic vibration does well in the removal efficiency. Combining with the results of indentation and scratching experiments, this paper analyzed further the influence of ultrasonic vibrations on the material removal with the force and cutting chips. The comparative results of ultrasonic and general scratches showed that ultrasonic vibration is good for reducing cutting force and make the chips little. In a word, ultrasonic vibration can improve the quality of machined surface.The evaluation citation of machined surface should be founded to investigate the quality of machined surface of SiCp/Al composites. To make up the disadvantage for the 2D roughness characterization, the 3D roughness parameters(amplitude and spatial parameters) were chose to evaluate the machined surface. Ultrasonic grinding experiments were carried out and the machined surface morphology was examined. Then the least squares method was used to extract the information of machined surface topography and the influence of cutting parameters on the machined surface with the 3D roughness parameters were analyzed. The results showed that 3D roughness parameters can describe the machined surface accurately and the high spindle speed and ultrasonic amplitude can lead to a high quality machined surface.The fractal was used to characterize the machined surface morphology for the roughness evaluation depends on the measurement scale. According to fractal theory, a three-dimensional fractal model was built and a fractal dimension calculation methods was optimized. Then the influence of sampling conditions and cutting parameters on the fractal dimension was analyzed. The results of comprehensive analysis of the fractal dimension and three-dimensional surface roughness showed that the small surface roughness and large fractal dimension indicates well surface. No matter the end or side ultrasonic grinding, the higher spindle speed and vibration amplitude, the higher quality of the machined surface.