CFRP制孔旋刨刀具的优化研究

发布时间：2018-06-03 03:29

本文选题：CFRP + 旋刨刀　；参考：《天津工业大学》2017年硕士论文

【摘要】：CFRP具有优异的力学性能,被广泛的应用在各个领域。然而,由于材料的各向异性、硬度高、导热性差等特点,在CFRP钻孔加工的过程中容易造成CFRP分层、孔出入口的撕裂和毛刺、刀具寿命降低等缺陷。针对以上问题,本文进行了以下四个方面的研究:首先,对CFRP的切削机理与缺陷进行研究,对单层CFRP板和钻孔后孔壁的微观形态进行观察和分析,可以得出:不同的θ角下加工CFRP形成切屑的形式不同;碳纤维断口和树脂基体涂附表面两部分组成了 CFRP的孔壁微表面;在0°～360°的范围内,表面的粗糙度呈对称分布。根据CFRP旋刨制孔时的受力模型得到切削力的理论公式,得出刀具的轴向力Fz的大小受到θ角、刀具的加工参数和几何参数的影响,对旋刨刀的优化设计做理论支撑。然后,对CFRP旋刨刀的可行性进行了实验验证,在不同的进给速度vf和转速n下对旋刨刀、麻花钻、套料钻进行钻削实验,对比分析得到三种刀具的轴向力Fz的大小,并用MATLAB进行数据拟合,得到三种刀具Fz的二元二次经验公式。分析可以得到:在n一定时,Fz随着vf的增大而增大,两者变化趋势几乎成线性关系;在vf一定时,Fz随着n的增大而减小,且vf越小,这种变化越明显;三种刀具在n = 5000r/min和vf = 150mm/min时,Fz旋刨刀Fz套料钻Fz麻花钻'即旋刨刀的轴向力最小,加工质量也最好,从而验证了旋刨刀的可行性。其次,对旋刨刀的结构进行设计,基于HASHIN准则,利用ABAQUS模拟CFRP三维钻削,通过改变刀具的几何参数,得到一个优化的值后,然后进行钻削正交试验,通过测量轴向力Fz和CFRP出入口的加工质量来判断比较,从而得出刀具几何角度最优组合为前角γ0= 15°后角α0= 10°主偏角kr = 75°副偏角kr=5°。按照对Fz的影响程度依次为:主偏角前角副偏角后角。和仿真结果一致,误差在可以接受的范围之内。用MATLAB拟合平均撕裂长度L(?)关于Fz的一元一次的曲线和表达式,表明两者呈正相关的关系。最后,采用超声C扫描对CFRP的分层缺陷进行分析,得出分层因子和Fz呈正相关;同时对优化后几何角度的旋刨刀进行刀具磨损实验,分析得出VB值和Fz的大小几乎呈线性的关系,因此可以用Fz来预测分层缺陷的程度和刀具的大致的磨损程度。旋刨刀的失效形式主要是后刀面的磨粒磨损以及刀具的崩刃失效。
[Abstract]:CFRP has excellent mechanical properties and has been widely used in various fields. However, due to the anisotropy, high hardness and poor thermal conductivity of the material, it is easy to lead to CFRP delamination, hole entrance tear and burr, and tool life reduction in the process of CFRP drilling. Aiming at the above problems, the following four aspects are studied in this paper: firstly, the cutting mechanism and defects of CFRP are studied, and the microscopic morphology of single layer CFRP plate and hole wall after drilling are observed and analyzed. It can be concluded that the forms of chips formed by processing CFRP under different 胃 angles are different, the fracture surface of carbon fiber and the coating surface of resin matrix constitute the pore wall micro-surface of CFRP, and the roughness of the surface is symmetrical distributed in the range of 0 掳~ 360 掳. The theoretical formula of cutting force is obtained according to the force model of CFRP rotary planing, and the influence of 胃 angle, machining parameters and geometric parameters on the axial force FZ of the cutting tool is obtained. The theoretical support for the optimization design of the rotary planer is made. Then, the feasibility of CFRP rotary planer is verified by experiments. The axial force FZ of the three kinds of cutting tools is obtained by comparing and analyzing the axial force FZ of the three kinds of cutting tools under different feed speed vf and rotational speed n. The binary quadratic empirical formula of three kinds of tool FZ is obtained by using MATLAB to fit the data. It can be concluded that the FZ increases with the increase of vf at a certain time, and the trend of both increases almost linearly, and the FZ decreases with the increase of n at a certain vf, and the smaller the vf is, the more obvious the change is. When n = 5000r/min and vf = 150mm/min, the three kinds of cutting tools have the minimum axial force and the best machining quality, so the feasibility of the rotary planer is verified. Secondly, the structure of the rotary planer is designed. Based on the HASHIN criterion, ABAQUS is used to simulate CFRP 3D drilling. By changing the geometric parameters of the tool, an optimized value is obtained, and then the drilling orthogonal test is carried out. By measuring the machining quality of the axial force FZ and the entrance of CFRP, it is concluded that the optimum combination of the geometric angles of the cutting tools is that the front angle 纬 0 = 15 掳, the rear angle 伪 0 = 10 掳, the main deflection angle KR = 75 掳, the pair angle kr=5 掳. According to the degree of influence on FZ, the main angle is the front angle, the second angle is the rear angle. In accordance with the simulation results, the error is within acceptable range. Fitting the mean tear length by MATLAB) The univariate curve and the expression of F _ z show a positive correlation between them. Finally, ultrasonic C-scan is used to analyze the delamination defects of CFRP, and the delamination factor is found to be positively correlated with FZ. At the same time, the tool wear experiments are carried out on the rotary planer with optimized geometric angle. It is concluded that there is a linear relationship between VB value and FZ value, so FZ can be used to predict the degree of delamination defects and the approximate wear degree of cutting tools. The failure form of the rotary plane cutter is mainly the abrasive wear of the rear tool surface and the failure of the cutting tool.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG716

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