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The delamination produced during drilling CFRP will affect its structural strength seriously. Delamination is closely related to the thrust force during drilling, which is closely related to the tool, so it is particularly important to choose the tools with appropriate geometric structure. Many scholars used tools with different geometric structure...
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At present, the problems that need to be solved urgently in CFRP drilling are delamination and tool wear, which are closely related to the distribution of cutting force on the cutting edge. The aim of this paper is to present a method to analyze the cutting force distribution on the main cutting edge of the drill. This method applies to the analysi...
Citations
... Baon et al. [12] found that double point angle tool is suitable for drilling CFRP, but is not suitable for drilling Ti and CFRP/Ti stacks. Liu et al. [13] proposed that the plane rake-faced twist drill is suitable for drilling CFRP, it was found that compared with the ordinary twist drill, thrust force generated by the plane rake-faced twist drill is smaller, which can effectively inhibit the hole machining damage. Alonso et al. [14] conducted drilling experiments on CFRP/Ti stacks using step drill and found that step drill has a certain effect in reducing thrust force, thereby effectively reducing drilling damage and achieving good hole quality. ...
The tool structure is an important factor affecting the damage of CFRP/Ti stacks machining. However, the impact of tool structure on the formation process of stacks hole damage cannot be fully revealed through experimental methods alone. In contrast, finite element simulation can effectively overcome the limitations of experiments. In this study, a numerical simulation model is established to investigate the relationship between step drill structure and formation process of CFRP/Ti stacks hole damage. Based on this, the research discusses the effect of step drill structure on the burr height of Ti layer, delamination of CFRP, aperture deviation, defects in hole surface. The results show that when the stacking sequence is CFRP to Ti, the burr height of Ti at hole exit decreases first and then increases with the rising of the ratio of primary drill bit diameter to secondary drill bit diameter (kd). When kd is 0.6, the burr height of Ti at hole exit is the lower. As kd increasing from 0.4 to 1.0, delamination factor of CFRP increases by 2.57%, which are affected little by the step drill structure due to the support of Ti. Besides, the aperture size deviation decreases first then increases with the rising of kd, and the minimum aperture size deviation is 2.09 μm when kd is 0.6. In addition, as kd is 0.6, the hole wall defect is fewer. In conclusion, step drill with kd of 0.6 is suitable for drilling of CFRP/Ti stacks.
... As the result of the preparation method of CFRP, most CFRP parts are made by near net shape process [3]. However, secondary machining, such as drilling and milling, is still required for assembly, form, and position tolerances [4,5]. CFRP has the characteristics of high hardness, low heat-conductive, heterogeneous, and anisotropic. ...
Carbon fiber-reinforced plastics (CFRP) are widely used in the aerospace and automobile industries because of their ultralight weight, high strength, excellent corrosion resistance, and anti-fatigue properties. However, the machining of CFRP is still challenging due to its super hardness and sensitivity to heat. Cryogenic milling is a kind of sustainable manufacturing process which is considered to have great potential for processing CFRP. This work is devoted to analyzing the tool wear and surface quality under dry and cryogenic conditions based on liquid nitrogen (LN2) and also provides a reference for selecting parameters of CFRP processing in industries. A series of tests were conducted under various cutting speeds, feed per tooth, and LN2 jet temperatures. In order to reveal the changing laws of tool wear and surface quality, flank wear bandwidth (VB), surface roughness (Sa) and burr factor (Fb) were carried out. The experimental findings have shown that tool wear is suppressed at high cutting speed and feed rate. In addition, surface quality is significantly improved at an appropriate temperature, and burr damage was also effectively suppressed with the temperature dropping, while tool wear is severer at − 196 ℃ than in dry conditions.
