Preparation Of Complex Shaped Cutting Tools With CVD Diamond Coating

In recent years,the development of coated tools has received widespread attention,and has been widely used in business.Because diamond has many advantages,such as high hardness,low friction coefficient,good thermal conductivity and good chemical stability,it is the best coating material for coated tools.Diamond coated tools are of great significance in machining ceramic materials,metal-based composite reinforced materials and other difficult-to-machining materials.high-quality coating is very important to improve the tool life,such as no spalling of diamond coating,small residual stress in the film and so on.Therefore,when the diamond coating tool deposition experiment is completed,it is particularly important to choose a suitable cooling process,so that the diamond tool without film delamination at the tool tip can be obtained.In this paper,diamond is deposited by hot filament chemical vapor deposition(hot filament chemical vapour deposition,HFCVD)method,and the gas sources are methane and hydrogen.Through reasonable arrangement of hot wire,the distance between cemented tungsten carbide tool and hot wire is controlled,and then diamond film is prepared on cemented tungsten carbide bit by HFCVD method.Finally,the optimized cooling process is used to cool down the substrates after deposition experiment.Finally,the micro-morphology of diamond films was characterized by scanning electron microscope(SEM),and the quality of diamond films was measured by Raman experiment.The experimental analysis of this paper is summarized as follows:(1)By comparing the experimental results of the three cooling processes,the cooling process with more uniform cooling rate is used to cool the substrates after deposition experiment,so that there is no diamond film delamination at the tip of the diamond coated cutter and the hot wire ignition phenomenon is reduced.(2)Diamond deposition experiments are carried out by using the optimized cooling process,and the experimental results of scanning electron microscope and Raman spectroscopy show that diamond coated tools can be obtained.No film delamination was found at the tip of diamond coated drill and reamer,but it was found at a tip position of the milling cutter.(3)By comparing the cutting experiments of coated tools with different cooling processes,it is found that the in-hole burr of carbon fiber plate machined by coated tools is reduced,the in-hole smoothness is increased,and the machining quality is significantly improved.By calculating the peeling factor of 0-90 holes,it is found that the peeling factor of coated tool is smaller than that of uncoated tool,and the peeling factor of coated tool of cooling process 2 is less than that of cooling process 1.By measuring the flank wear,it is found that the coated tool wear is reduced by 30%,and the coated tool wear of cooling process 2 is less than that of cooling process 1.Therefore cooling process 2 is selected as the final cooling process.(4)The temperature field of tool matrix is simulated by finite volume method using ANSYS Fluent software.Through the temperature cloud diagram of the whole tool,it can be seen that the overall temperature distribution of the tool is 880 ?-980 ?,and the overall temperature difference of the tool is 100 ?,which is suitable for diamond growth.Compared with the experimental temperature measurement results,the temperature error at the top of the tool is less than 5%.