Study On The Combined Machining Technology Of Sawing And Grinding For Aramid Composites

Being one of the advanced composite materials, aramid composites have a unique combination of properties such as high specific strength and stiffness and excellent impact resistance, which have now been widely used in armour protection and aerospace industry. Machining operation is absolutely necessary in manufacturing process of composites structure. However, owing to the complicated heterogeneous composition resulted in nonhomogeneity and anisotropy, composite is one of the representative difficult-to-cut materials. Machining technology of aramid composites has a great influence on the performance and service life of the composite structure. It proved to be the key factor to dominate the development and application of the material.In this paper, the study was carried out on aramid/epoxy composite materials. Aiming at the problem of poor machinability in conventional machining of aramid composites, the formation reason for machining damage was analyzed. By studying the way to minimise damage in machining of aramid composites, a combined machining theory based on sawing and grinding mechanism was proposed. Furthermore, machining experiments were conducted to explain performance of the sawing-grinding tools. The main contents and academic achievements in this investigation are shown in the following.(1) Based on the damage characteristics of machined aramid composites, the peculiar properties resulted in poor machinability were summarized. Theoretical analysis by contact mechanics was conducted. Meanwhile, scratching experimental verification was proceeded. The tool sharpness proved to be the key factor to cut off aramid fibers effectively. Reliable theoretical foundation was established to achieve damage-free machining quality of aramid composites.(2) Aiming at the poor machinability of aramid composites, a combined machining theory based on sawing and grinding mechanism was proposed innovatively. The sawing mechanism and grinding mechanism were explained respectively by experimental investigation. New cutting tool and drilling tool were designed and developed. Furthermore, the tool structure parameters were optimized in the next research.(3) Machining tests showed that the sawing-grinding machining theory can restrain and minimize damages effectively. Full factorial experiment for cutting aramid composites was carried out. The machining process quality was discussed particular in different cooling conditions and cutting parameters. Consequently, cutoff process by the sawing-grinding cutting tool was explored and optimized.(4) The superiority of sawing-grinding drilling tool was tested and verified by contrastive experiment. In order to decrease the accumulation of cutting heat during drilling of aramid composites, atomizing gas cooling method was proposed and the cooling system was established. Based on the optimization of tool structure parameters, the effect of cooling and chip removal was enhanced obviously.