Abstract
Currently, hole making processes in carbon fiber reinforced polymers (CFRP) generate powdered chips that cannot be automatically recovered in real time. The present work attempts to solve this problem using a new drilling-chip removal system called the suction-type internal chip removal system. It can discharge the powdery chips generated in the CFRP hole making process in a timely and effective manner during the drilling process. Based on the requirements of the drill bit used in this system, the following studies are carried out in this work: (1) Using statistical methods, the chips produced in CFRP hole making were classified, the chip distribution was analyzed, and the study of the influencing factors of chip size were completed; (2) based on these studies and the gas–solid two-phase fluid mechanics, a FLUENT simulation is used to define the center distance and center angle of the inner runner for the design of the drill bit. The influence of the center distance of the inner runner, the center angle of the inner runner, and the cross-sectional shape of the inner runner on the chip removal effect of the inner runner of the tool is given. Finally, by fabricating the chip removal system and drill, the correctness of the internal flow channel structure design of the internal chip removal drill was verified.
Highlights
Carbon fiber composite materials are widely used in the manufacture of aircraft structural parts, such as rudders, elevators, upper cabin floor beams, and rear panels due to their excellent physical and mechanical properties, such as light weight, high specific strength, high specific rigidity, and good formability [1,2,3]
(1) Experimental conditions The CFRP material used in the experiment was provided by Hafei Industry Co., Ltd., with a thickness of 4.5mm; The drill used in the experiment is a special CFRP drill bit of SD205-7.963-40-8R1-CX31 produced by Seco; The processing equipment used in the experiment is a VDL-1000E CNC milling machine produced by Dalian Machine Tool Factory; The processing parameters used in the experiment are shown in Table 1; The chip size was measured with an ultra-depth-of-field microscope (Keyence VHX-1000)
Carry out the cutting experiment according to the machining parameters shown in Table 2-1, and some of the results obtained from the experiment are shown in Figure 2; Fig.2 Cutting chips for hole making with CFRP
Summary
Carbon fiber composite materials are widely used in the manufacture of aircraft structural parts, such as rudders, elevators, upper cabin floor beams, and rear panels due to their excellent physical and mechanical properties, such as light weight, high specific strength, high specific rigidity, and good formability [1,2,3]. Through analysis, it can be known that whether it is the design of the internal flow channel of the internal chip removal tool or the calculation of the critical condition of the internal chip removal system, it is related to the content of gas-solid two-phase fluid mechanics. The current research on gas-solid two-phase fluid mechanics has a certain foundation: For example, Dai et al [12] used Savage's particle dynamics model to study the flow characteristics of high-concentration pulverized coal pneumatic conveying in the elbow, and established a mathematical model for high-concentration pulverized coal pneumatic conveying, The model is used to conduct mathematical simulation research on the pressure drop and flow distribution law in a vertical turning horizontal 90° elbow. Based on the above-mentioned literature research, this paper will study the content of the internal flow channel design of the internal chip removal drill bit used in the suction type internal chip removal system in combination with the existing research content of gas-solid two-phase fluid mechanics. The following is based on experiments to classify the chips generated during CFRP hole making, and study the factors affecting the chip size and the main distribution area after the chips are generated
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