Drilling is an important process in the post-processing of carbon fiber composites. However, carbon fiber composites have the characteristics of large hardness, high strength, poor thermal conductivity, anisotropy and low interlayer strength. Therefore, it is very difficult to process. Some small carbon fiber manufacturers have a high processing scrap rate. Through the experimental research and analysis on high speed drilling of carbon fiber / epoxy matrix composites,
1, Throughout the high-speed drilling process, the drilling force changes regularly with time. When the drill starts to drill in, the axial force and torque will increase from zero to zero. When the main cutting edge of the drill participates in cutting, the axial force and torque reach the maximum value, and the steady state After the drill bit drilling process begins, the backing material reduces the rigidity of the drill bit support, resulting in a gradual reduction of the knife phenomenon, axial force and torque until the drill bit is fully drilled and its value becomes zero. Experimental observation found that this law is the same in all kinds of drilling reference.
2, drilling carbon fiber / epoxy composite materials, should not be used high-speed steel drill, carbide drill should be used. The use of high-speed steel drill bit axial force far greater than the use of carbide drill, which is due to the different angles of the two drill bits. Even with the same drilling parameters, the degree of wear of the two tools is also very different.
3, the constant feed rate, the higher the bit speed, the smaller the axial drilling force, which is because of the higher cutting speed to produce more cutting heat, the workpiece material strength and hardness decreased in the Under the condition of constant rotating speed, the larger the feed is, the larger the axial force is, and the more obvious the influence is. This is because as the feed rate increases, the thickness of the cutting layer increases, so the axial force will increase.
4, at the same speed and feed rate, the drill has drilled the more holes, the greater the axial drilling force. And the higher the speed, the faster the tool wear, so that the axial force increases faster.
5. Under the condition of constant speed and feed rate, the bigger the drill diameter is, the larger the drilling force is. Because the cutting area of drill cutting edge increases with the increase of drill diameter, the cutting area is the size of cutting force One of the most important factors is that the increase of cutting area will lead to the increase of cutting force, which is consistent with the change rule of axial force of common metal material.
6, the other parameters in the same conditions, the greater the thickness of the carbon / epoxy composite, the greater the axial drilling force. This is because the drilling is performed in a relatively closed space, the dust-like cutting is difficult to discharge, and the difficulty increases with the increase of the drilling depth. A large amount of cutting jamming in the depth of the hole greatly increases the distance between the drill bit Friction, so the axial force increases, tool wear increased.
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