Design-Manufacturing And Performance Studies Of Diamond Drill

Due to high specific strength and specific stiffness, high-temperature and corrosion resistance and other excellent performance, the Hardworking and Non-ferrous materials are widely applied in the aerospace, automotive, manufacturing and other fields, which demands higher machining quality and efficiency. However, such materials are all difficult to cut and the tool wears quickly. And the problem is especially serious when drilling. With high hardness, wear resistance and many other perfect properties, the diamond tools are popularly used in turning and milling, but there is little study in drilling. Based on the analysis of the composite materials machining and diamond drills, the design and manufacturing problems and cutting performance of diamond drills for high-precision machining of non-ferrous materials are discussed in this paper. The main content is summarized as follows:In this thesis, flat grinding and cone grinding models are established by Pro/E, compressive strength of the PCD blade are analyzed, the blade compressive strength is researched as result of many factors such as different flank shape, posterior horn, apex angle, the maximum axial cutting force value that the blade can withstand is obtained. The torsion rigidity of diamond bits with different flutes, radial cross-section are comparative studied. And the dissertation comparative study the effect of structural parameters change on the diamond drill strength and stiffness.Chip disposal grooves of different cross-sectional shape and different radial spiral groove of the torsional rigidity of the diamond drill has been analyzed in Chapter II. The establishment of straight and spiral groove of two different three-dimensional models of diamond drill bits, Obtained the twist of the drill through finite element calculation, the straight slot diamond drill has better anti-reverse than the spiral groove, the torsional rigidity of Arc-type cross-sectional shape of diamond drill bit is better than the traditional cross-sectional shape. In addition, by changing the structure design parameters of diamond drill bit simulate drill bit during drilling force to analyze the situation, comparative study of the drill core thickness, helix angle, spiral groove length on the stiffness strength of diamond drill bit. With the increase in the thickness of the core drilling, diamond drill bit radial displacement, axial displacement and angular displacement are reduced, show that the greater thickness of drill core, the better stiffness of the drill. Drill core thickness is too large, would reduce the capacity of drill bits of space debris. A large number of chips piled up in the tank will increase the wear of drill. At the same time, that can reduce the life and processing quality. Moreover, an increasing in the thickness of drill core implies that the length of horizontal edge increased. This could lead to worse conditions for cross-cutting edge, In particular, the PCD blade of the diamond drill bit with a hard and brittle nature. If the horizontal edge is too long, will lead to the increase of axial force, Increased the failure probability in the drilling of the blade. Therefore, that should not be an excessive increasing in diamond bit drill core thickness. Drill helix angle increases, the maximum angular displacement increases, and the stiffness declines. Front angle of Diamond drill bit is zero, helix angle does not affect on the cutting edge, the large Helix angle more conducive to discharges the chip, Can be reduced the possibility of failure drill which because the cuttings BTA stored in the flutes. But the helix angle is too large that would increase distance and BTA resistance. If the BTA is not smooth, chip tank will accumulate in flute, which leading to deterioration of cooling conditions. PCD diamond drill bit blade is easy to graphite at a high temperature. Another, the cutting forces is small in the processing by diamond tool. Therefore, considered that diamond drill bit can choose the larger helix angle in the case of smooth chip. With the drill spiral groove length increases the torsional rigidity will down. The analysis also has the stress distribution of the drill, The results show that the stress concentration at the horizontal edge, spiral groove root and cutting edge,which is the most easily damaged parts of drill bits.Drilling is the most complex machining and one of the most widely application process, as the special nature of drill geometry makes it a complex process. If the inappropriate choice of machining parameters, that could create the drilling force is too large, tool life is short, vibrations generated in the process as well as the drill breaks, etc. The mathematical model of diamond drilling SiCp/Al composite materials is gave, and the drilling force based on this model is simulated. Predict the processing of diamond drill bits suffered axial force and torque as well as the stress distribution in the workpiece, Analyze and compare the different cutting parameters of diamond drill axial force and torque suffered by the trend of changes, provide a reference for follow-up performance test. Simulation to be different cutting parameters of cutting force value, Draw out the relationship line between cutting force and cutting parameters, Observational studied that with the increasing feed rate the drilling axial force and torque are increasing. With the increase of cutting speed the torque and axial force have small changes.In drilling experiment, the relationship between drilling parameters and cutting force, the diamond drill wear and breakage, the hole machining quality are studied. The result shows that, when diamond bit drilling SiCp/Al composite materials, as the feeding increases, the thrust force increases quickly and significantly, and the thrust force rarely change with the cutting speed increasing, which are in accordance with the simulation results. And in drilling experiment, the diamond is including wear and breakage, which include the rake face wear, flank wear and the horizontal edge of the wear. The mainly diamond wear is abrasive wear, adhesive wear, diffusion wear and chemical wear. Analysis the relationship between with the flank wear VB value and the number of drilling by diamond drill bits and high-speed steel drill. The high-speed steel drill has the serious wear after drilling one hole, not suitable for machining SiCp/Al composites. Diamond drill bit is drilling SiCp/Al composites ideal tool, but it must be in a coolant effect. At last, the effect of cutting parameters on the roughness of the axial hole is studied. Studies have shown that the feed plays a key role in the level of the surface roughness, the axial surface roughness value increases with feed rate. Drilling speed has a little effect on surface roughness Ra, the axial surface roughness value increases with high cutting speed, because of that, when the speed is too high, the vibration cutting increased.