The Technology Research Of Diffusion And Grinding Compound Machining Polycrystalline Diamond (PCD)

Polycrystalline diamond is a staggered polycrystal of diamond grain, and referred to asPCD. Its structure its hardness and wear resistance are closed to the natural diamond, it hasisotropic, economic and other advantages. PCD was widely used in automotive, aviation,aerospace and so on, such as the traditional processing of optical glass processing, stoneprocessing, ceramics processing, hard and brittle materials processing and the traditionaldifficult processing field. And it plays a tremendous role in promoting a variety of industrialdevelopment. But it was difficult to process because of high hardness and high wear. Howefficient and precision machining is the key technology that need to be settled urgently.Domestic and foreign scholars do a lot of experiments and research for this problem, and theyhave made some achievements. At present, the main processing methods include the grindingprocessing, electrical discharge machining, laser processing, chemical processing, etc.However, these processing methods have some problems in accuracy and efficiency. So a newmethod of processing and processing mechanism was studied, and it has the vital significancefor occupying the frontiers of processing technology and promoting the development of PCDprocessing technology.Through the research of polycrystalline diamond organizational structure, according tothe machining characteristics of different components in polycrystalline organization, a newmethod of composite processing was proposed. In this component processing, polycrystallinediamond component was removed by the diffuse processing mechanism, binder componentwas removed by grinding machining. We can obtain high removal efficiency and good surfacequality by reasonable combination of two kind’s removal. The special grinding plate wasdesigned by alloy powder and a certain concentration of hard abrasive sintering suppressiondiffusion and grinding processing PCD materials. By microscopic observation of the variousstages in the process of grinding the chip and the machined surface, the mechanism ofdiffusion and grinding composite processing was revealed, the main factors and laws ofimprove processing efficiency and accuracy was determined in the composite processing, theeffective way of improve processing efficiency and accuracy was explored. The specificresearch work is as follows: 1. According to different polycrystalline components, the mach inability complexprocessing mechanism was studied. Through the study of the structure of polycrystallinediamond, structure model of polycrystalline different manufacturability component wasestablished, composite processing experiment device was designed, and a grind cutting tool(grinding plate) that is made of metal and grits was developed. The PCD surface and surfacemorphology of grinding disk after grinding was studied by SEM and other analysis methods,the research process of the cut diamond components removal and spread binder componentsresearch the role of cutting removal was determined, the mechanism of diffusion and grindingcompound machining polycrystalline diamond was diffuse removal and mechanical removal.2. The studies of main influencing factors. Through the experiment of diffusion andgrinding compound machining, the main factors and laws of improve processing efficiencyand accuracy was determined in the composite process, the effective way of improvingprocessing efficiency and accuracy was explored.(1) The study of organization composition, grits properties, particle size impact PCDprocessing efficiency and accuracy about composite grinding plate. According to diffusiontheory, different components will affect the removal efficiency of diamond composition andbinder components of polycrystalline diamond. Through the experiments of grinding plate ofmetal and hard abrasive grinding PCD materials, the binding agent to remove the effect ofPCD materials was studied by SEM and other analysis methods, drawn a conclusion: with theincrease of the hard abrasive, PCD binder removal efficiency gradually increased. So it hasimportant significance to improve the processing efficiency of the PCD material.(2) The study of grinding speed impact processing efficiency. According to diffusiontheory and friction principle, the change of grinding speed will affect the change of grindingsurface temperature. It has important influence on removaling the diamond components. Thesingle factor method was studied in this paper, the grinding speed impacts on processingefficiency was studied under the same conditions in the workpiece speed and feed rate. Withthe increase of grinding speed, processing efficiency presents a parabolic law. Anexperimental basis was provided to improve the processing efficiency of the PCD material.(3) The impact study of grinding force and grinding temperature distribution in thegrinding process. According to heat transfer theory, the main factors of grinding force andgrinding temperature changes affect the diffusion conditions in the process of grinding. In thispaper, the temperature field distribution change was simulated by finite element simulationsoftware, and the temperature was measured by home-made temperature measurement system. The results show that the two results are basically consistent, temperature field numericalsimulation is correct. Study on the composite processing of cutting surface temperaturechange has important significance by combining the two.3. The study of actual grinding experiment. PCD materials were grinding processing bycomposite processing method. Composite processing with diamond grinding wheel grindingwas compared in machining efficiency, surface quality and so on. The results show thatcomposite workpiece surface quality can achieve high accuracy; diffusion and grindingcompound machining is superior to diamond grinding wheel grinding.