Study On High-Efficiency Grinding Key Technology For Special-Shaped Surface Of Granite Based On Fractal Thoery

The granite special-shaped products have been widely used for its exquisite appearance, luxurious and elegant tones and wear resistance, corrosion resistance and other stable physical and chemical properties in the fields of architectural decoration, craft and art, life appliances, precision machine and development toward high-level, art and precision. The creative design industry of decorative granite products is based on special-shaped granite products, therefore, the social demanding, the quality and value-added for granite special-shaped products are increasing. Considering of the products processing status and foreign research focus, the study of high-efficiency grinding technology for special-shaped products of granite based on fractal was advanced. The paper was conducted by equipments, tools, materials and process of high-efficiency grinding, the critical technology system was improved for high-efficiency grinding technology, the definition and theory criteria was perfected, the theory analysis for grinding mechanism was conducted based on fractal theory. The fractal characters of machining processing were studied and the fractal models were constituted too. The relations between fractal characters and machining processes and efficiency were studied by experiments.The fractal grinding mechanism of granite special-shaped surface was studied by analysis the fractal characters of the diamond single particle grinding curve, crack spreading and mineral crystal rupturing. The diamond profiled wheel is selected to grinding the irregular surface of granite. The diamond single particle grinding curve model was obtained by analysis of the profiled surface grinding process and the specialty of diamond profiled wheel, the geometry angles and the removal material volume were analyzed and the arc length and the fractal dimension of the grinding fractal curve were deduced. The mineral crystal fracture fractal model was established and the removal mechanism and process granite materials fractal fracture was studied.The mathematic model of grinding force fractal dimension with process parameters was advanced. Granite profiled surface processing is intermittent grinding, the grinding force fluctuates greatly, the dynamic characteristics have a fractal law. Through establishing the diamond single particle force model derived tangential force, normal force and axial force relationship analysis of the variation of the size and direction. As a basis for establishing the diamond forming agglomerates force model, the force fractal character of agglomerates was analyzed and the calculate method of the fractal dimension was confirmed too. Experimental study of law based on orthogonal experimental design method for the1/4arc profiled surface grinding Wulian red granite grinding force and its fractal dimension. Cutting speed, feed rate and cutting depth of three factors, each of the four levels of each four-level orthogonal three factors, its three directions grinding force were measured and the fractal dimension of force calculated. Range analysis, analysis of variance and regression analysis of grinding forc were conducted, the mathematical model of grinding force was established. The mathematic model of grinding force fractal dimension with process parameters was advanced. The relationship between grinding force fractal dimension and grinding force was analyze to the linear function, namely, the force increasing the fractal dimension increasing, the force decreasing the fractal dimension decreasing too.The high-efficiency process parameters optimization model was established with the evaluation indexs of material removal rate (MRR) and grinding force fractal dimension (GFFD). The signal-to-noises (S/N) of MRR and GFFD were calculated in different process parameters with the MRR larger-features and GFFD small-features using the Taguchi method. The main effect charts of S/N and mean were made and the process parameters were optimized. Moreover, the optimum parameter was verificated by experiments.The granite grinding debris fractal model was advanced and the evaluation and grading forecast research on grindability of granite specia-shaped surface were studied based on fractal dimension of granite debris. Through analyzing fracture process broken into crumbs of granite special-shaped surface, the plane and three-dimensional space fragmentation model were established and the fractal crushing characteristics were analysed. The relationship between the the debris fragmentation fractal dimension and the process parameters was studied by quadratic response surface methodology experiment and the factors impacting debris fragmentation fractal dimension were analysed. Select SiO2, quartz, Shore hardness, density, compressive strength, flexural strength and wear rate of the seven granite grinding influential indicators, the study on grindability classification were conducted by triangular fuzzy number TOPSIS analysis method on ten typical granite materials. Then analysed and verificated by1/4arc profiled surface grinding experimental. Selecting the Y direction grinding forces and granite debris fractal dimension as evaluation indicators. Univariate analysis and multivariate comprehensive analysis of the experimental results were conducted, using the linear functions, exponential functions, logarithmic functions to establish the mathematical evaluation model between granite debris fragmentation fractal dimension with granite performance indicators. The grinding grading standards were established based on granite debris fractal dimension and the grindability of ten granite materials were classificated, the experimental results is consistent to FAHP-TOPSIS conclusions.The purpose of this study is to improve the efficiency of grinding granite special-shaped products, reduce production costs. The research has theoretical and practical significance to the production and processing and promotes granite special-shaped products processing to take the standardized, low-cost, high-efficiency and high value-added processing. It also has significance guiding for discipline construction of granite processing technology. Meanwhile, the research ideas and methods of the paper will also play a stimulating role to stone processing technology.