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为了研究轴向低频振动辅助钻削方式在皮质骨钻削过程中对进给力的影响,对全钻头和横刃部分进给力进行了对比试验,并对切削刃切削单元的运动学和瞬时加工过程进行了分析。对比试验结果表明:在相同的钻削参数下,与常规方式相比,轴向低频振动钻削方式的全钻头进给力最大可减小约60%,横刃部分进给力可减小60%~80%。依据运动学分析和典型骨屑形态对比可以得出:在特定的钻削参数和振动参数配合下,轴向低频振动钻削方式可以实现钻头-工件周期性分离运动,显著影响瞬态加工过程,是进给力显著减小的主要原因之一。 相似文献
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为了解决碳纤维复合材料(CFRP)钻孔加工过程中出现的撕裂、毛刺、分层等问题,以及将碳纤维复合材料更好地应用到机械制造行业中,进行了碳纤维复合材料的钻孔试验.通过实验研究了碳纤维复合材料的钻孔缺陷,分析了碳纤维复合材料钻孔加工的主要缺陷分类,以及钻削力、刀具的锋利性、钻削温度等因素对孔加工质量的影响,建立了钻削速度、进给速度与钻孔质量之间的关系;采用DM2500M金相显微镜以及KEYENCE VHX-1000三维显微系统进行了相关的试验.研究结果表明,钻孔加工缺陷出现部位呈现一定的区域性,钻孔毛刺、撕裂缺陷主要集中在出口部位,入口处几乎没有毛刺、撕裂等缺陷;随着进给速度的减小和主轴转速的增大,钻孔缺陷能够得到明显的改善;采用PCD钻头加工复合材料时宜在中、高转速下进行,高转速下钻头切削刃更易切断纤维,可以得到质量更高的钻孔. 相似文献
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麻花钻磨损特性的研究 总被引:5,自引:1,他引:4
通过对调质合金结构钢的大量钻削试验,研究了麻花钻磨损区的图形特征和磨损机理以及钻头失效与磨损图形参数、钻头切削寿命与钻削速度的关系。结果表明,麻花钻的磨损具有非线性特征,钻头转角和主刀刃及横刃区有两个显著不同的磨损区,随钻削速度的提高,这两个磨损区的特征差异及磨损带宽度之比明显增大。在钻削速度较低、钻头失效时,两个磨损区为较均衡的磨粒磨损和粘结磨损;钻削速度较高时,转角区剧烈的粘结磨损和氧化磨损使钻头加快失效,而主刀刃及横刃上的磨损却很小。受此影响,麻花钻的磨钝标准、耐用度问题较为复杂,钻头的寿命(T)-速度(V)曲线的泰勒特性范围很窄。 相似文献
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为避免或减少钻削出口分层缺陷,控制钻削轴向力不超过出口分层临界轴向力具有重要的实际意义.将钻头横刃上的轴向力分为两部分,其一是横刃前刀面与碳纤维增强复合材料(Carbon fiber reinforced polymers,CFRP)之间作用力的轴向分量,其二是横刃圆弧与CFRP接触力的轴向分量.基于复合材料的细观力学... 相似文献
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为了提高汽车轻量化所用钛合金的钻削质量,以TiC4合金板为例,开展超声振动辅助钻削动力学及钻孔过程试验研究。构建了动力学模型并完成各项参数的估计,完成模型的超声振动测试。动力学试验结果表明:当系统到达钻削阶段时,形成了相应的倍频。钻头除了存在沿自身匀速旋转运动以外,还沿进给方向形成了明显的简谐激振力,从而产生了而具有周期性的切削厚度。按照设定进给速度与主轴转速参数,对钛合金工件实施钻孔测试。钻孔试验结果表明:设置轴向振动之后,轴向力明显的下降,且变化更为平稳。超声振动方式能够增强钻头切削能力,促进断屑并快速排出,由此获得稳定的钻削效果。该研究对提高钛合金板的钻削质量具有很好的实际应用价值,易于推广实现。 相似文献
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GH4169高温合金的薄壁钻孔与厚壁钻孔相比有特殊性,运用ABAQUS软件进行钻削GH4169高温合金薄壁件的仿真,研究钻削加工过程中钻削参数和工件厚度对钻削力的影响规律及变化特征,分析应力的分布规律。结果表明:钻削初期,横刃的挤压和主切削刃切削长度的增加使钻削力和扭矩增大;稳定钻削阶段,横刃切出后,主切削刃切削长度不变切削直径增加,钻削力和扭矩稳定增加;钻削后期,副切削刃参与切削,主切削刃切削长度减小,轴向钻削力和扭矩减小,但副刃与孔壁的挤压摩擦,曲线波动较大;钻削速度、进给量及工件厚度的增加都会导致轴向钻削力和扭矩的增加;钻削时的最大应力分布在横刃和主切削刃与工件的接触部位。 相似文献
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碳纤维复合材料/钛合金叠层钻孔质量研究 总被引:9,自引:0,他引:9
碳纤维复合材料(Carbon fiber reinforced plastic,CFRP)/钛合金叠层的钻孔机理不同于单层材料钻孔,钛合金切屑在排出孔外过程中会对CFRP孔质量造成损伤。为了探究CFRP在叠层钻孔时的质量特性,设计正交试验分析了钛合金切屑和切削参数对CFRP层钻孔质量的影响。观察了轴向切削力和力矩的变化以及钛合金切屑形态,分析CFRP层孔径超差和入口撕裂的机理。结果表明:大进给量条件下,高温、高硬度的钛合金切屑会对CFRP产生严重的侵蚀,是导致CFRP孔径超差的主要原因,并会增大入口撕裂程度;CFRP入口撕裂主要产生在切削速度和纤维方向夹角θ=45°的位置,低切削速度不利于切削CFRP,会加大入口撕裂程度。因此,应使用小进给量钻削钛合金层,使用大切削速度钻削CFRP层;在保证钻头强度的前提下,推荐使用具有较大容屑空间的钻头。 相似文献
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《Measurement》2016
Milling is the most feasible machining operation for producing slots and keyways with a well defined and high quality surface. Milling of composite materials is a complex task owing to its heterogeneity and the associated problems such as surface delamination, fiber pullout, burning, fuzzing and surface roughness. The machining process is dependent on the material characteristics and the cutting parameters. An attempt is made in this work to investigate the influencing cutting parameters affecting milling of composite laminates. Carbon and glass fibers were used to fabricate laminates for experimentations. The milling operation was performed with different feed rates, cutting velocity and speed. Numerically controlled vertical machining canter was used to mill slots on the laminates with different cutting speed and feed combinations. A milling tool dynamo meter was used to record the three orthogonal components of the machining force. From the experimental investigations, it was noticed that the machining force increases with increase in speed. For the same feed rate the machining force of GFRP laminates was observed to be very minimal, when compared to machining force of CFRP laminates. It is proposed to perform milling operation with lower feed rate at higher speeds for optimal milling operation. 相似文献
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C/E复合材料螺旋铣削制孔方法抑制缺陷产生的机理 总被引:14,自引:0,他引:14
传统钻削加工碳纤维/环氧树脂(Carbon/epoxy,C/E)复合材料时容易产生加工缺陷,而螺旋铣削作为一种新的制孔方法在航空材料的加工中逐渐受到关注。为分析螺旋铣削制孔方法抑制缺陷产生的机理,以传统钻削加工为参照,分别利用螺旋铣削及传统钻削两种方法对C/E复合材料进行制孔试验,并对螺旋铣削与传统钻削刀具的运动轨迹进行分析。在具有相同的加工效率及刀具切削速度的基础上,对两种加工方法的加工参数进行优化。进行制孔对比试验,并对制孔过程中的切削温度、切削力及加工质量进行检测与分析。结果表明,切削温度是影响C/E复合材料制孔质量的重要因素,且由于螺旋铣削制孔时的切削温度显著低于传统钻削制孔温度,因此螺旋铣削制孔质量明显优于传统钻削制孔质量。螺旋铣削制孔时的切削温度较传统钻削时降低69℃以上,降幅大于36%,因此有效避免了制孔出口处的撕裂及分层现象。 相似文献
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Tao Chen Suyan Li Bangxin Han Guangjun Liu 《The International Journal of Advanced Manufacturing Technology》2014,72(9-12):1639-1645
This work investigates the cutting force and surface micro-topography in hard turning of GCr15 bearing steel. A series of experiments on hard turning of GCr15 steel with polycrystalline cubic boron nitride (PCBN) tools are performed on a CNC machining center. Experimental measurements of cutting force, 3D surface micro-topography, and surface roughness of the workpiece are performed. The 3D surface micro-topography of the workpiece is discussed, and the formation mechanism of the 3D surface is analyzed. The influence of cutting speed and feed rate on cutting force and surface roughness are discussed. The 2D and 3D surface roughness parameters are compared and discussed. It is found that feed rate has greater influence on cutting force and surface roughness than cutting speed and there exists the most appropriate cutting speed under which the minimum surface roughness can be generated while a relatively small cutting force can be found. Recommendations on selecting cutting parameters of hard turning of GCr15 steel are also proposed. 相似文献
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Carlos E. H. Ventura Heitor S. Chaves Juan Carlos Campos Rubio Alexandre M. Abrão Berend Denkena Bernd Breidenstein 《The International Journal of Advanced Manufacturing Technology》2017,88(9-12):2557-2571
The aim of this work is to define the cutting conditions that allow the dry drilling of carbon fiber reinforced epoxy (CFRE) composite materials taking into consideration the quality of the drilled holes (the exit delamination factor and the cylindricity error) and the optimum combination of drilling parameters. A further aim is to use grey relational analysis to improve the quality of the drilled holes. The machining parameters were measured according to 33 full factorial parameter designs (27 experiments with independent process variables). The experiments were carried out under various cutting parameters with different spindle speeds and feed rates. Drilling tests were done using WC carbide, high-speed steel (HSS), and TiN-coated carbide drills. The experiment design was accomplished by application of the statistical analysis of variance (ANOVA). Results show that the thrust force is mainly influenced by the tool materials and the feed rate, which has a strong influence on the exit delamination factor. On the other hand, the spindle speed particularly affects the cylindricity error of the holes. Correlations were established between spindle speed/feed rate and the various machining parameters so as to optimize cutting conditions. These correlations were found by quadratic regression using response surface methodology (RSM). Finally, tests were carried out to check the concordance of experimental results. 相似文献
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Cutting forces prediction in generalized pocket machining 总被引:1,自引:1,他引:0
Zhao-cheng Wei Min-jie Wang Xian-guo Han 《The International Journal of Advanced Manufacturing Technology》2010,50(5-8):449-458
Cutting force prediction is important for the planning and optimization of machining process. This paper presents an approach to predict the cutting forces for the whole finishing process of generalized pocket machining. The equivalent feedrate is introduced to quantify the actual speed of cutting cross-section in prediction of cutting force for curved surface milling. For convenience, to analyze the process with varying feed direction and cutter engagement, the milling process for generalized pocket is discretized into a series of small processes. Each of the small processes is transformed into a steady-state machining, using a new approximation method. The cutting geometries of each discrete process, i.e., feed direction, equivalent feedrate per tooth, entry angle, and exit angle are calculated based on the information refined from NC code. An improved cutting force model which involves the effect of feed direction on cutting forces prediction is also presented. A machining example of a freeform pocket is performed, and the measured cutting forces are compared with the predictions. The results show that the proposed approach can effectively predict the variation of cutting forces in generalized pocket machining. 相似文献
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Analytical modelling of slot milling exit burr size 总被引:1,自引:0,他引:1
Seyed Ali Niknam Victor Songmene 《The International Journal of Advanced Manufacturing Technology》2014,73(1-4):421-432
A computational model was recently proposed by authors to approximate the tangential cutting force and consequently predict the thickness of the exit up milling side burr. To calculate the cutting force, the specific cutting force coefficient with respect to material properties was used. The model was sensitive to material yield strength and few cutting and tool geometrical parameters. However, the effects of cutting speed, tool coating, and tool rake angle on burr size were neglected. Other phenomena that could affect the burr size such as friction and abrasion were not taken into account either. Therefore, in the current work, a mechanistic force model is incorporated to propose a burr size prediction algorithm. The tangential and radial forces are calculated based on using specific cutting force coefficients in each direction. Furthermore, using the new approach, the burr size is predicated and the effects of a broad range of cutting parameters on burr size and friction angle are evaluated. Experimental values of burr size correlated well with prediction. It was found that the cutting speed has negligible effects on force and burr size. Lower friction angle was recorded when using larger feed per tooth. Consequently, thinner exit up milling side burr was obtained under high friction angle. 相似文献
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Compared to metallic materials, carbon fiber-reinforced plastics (CFRPs) have lower thermal conductivity and minor thermal expansion coefficient. Despite this, their machining can generate accuracy errors if the cutting temperature is not controlled. In this paper, an experimental study of slotting of multidirectional CFRP laminate (G803/914) with three micrograin carbide burr tools with different geometries is considered in order to investigate tool-workpiece contact point temperature, chip temperature, machined surface damage, subsurface defects and tool degradation. The experiment is made on a computer numerical control (CNC) machine with cutting speed ranging from 80 to 200 m/min and feed per tooth from 0.008 to 0.060 mm/rev/tooth. The data were analyzed in order to establish empirical models showing the dependence of cutting temperature on tool geometry and cutting conditions. Based on the results, it is concluded that cutting speed is the factor influencing cutting temperature the most, the heat generated during slotting is removed mainly by chips and the chip temperature is greater than the tool-workpiece contact temperature of about 18.5°C on average for the three burr tools. 相似文献