CFRP/钛合金叠层材料超声振动辅助钻孔实验研究

采用超声辅助钻孔工艺对碳纤维复合材料(CFRP)/钛合金叠层构件的钻孔质量进行实验研究。分析了叠层材料钻孔轴向力的变化规律、超声振动及钻孔工艺参数对轴向力的影响、复合材料层的孔口形貌等。实验结果表明:叠层材料的钻孔轴向力在钻孔过程中呈现出非常大的波动,加工钛合金层时的平均轴向力比加工复合材料层时大4倍。超声振动钻孔对复合材料剥离分层引起的轴向力波动具有很好的抑制作用,但是在加工钛合金层时,超声振动并不能有效抑制钻孔轴向力的波动。在加工单层复合材料时,超声振动钻孔的质量显著好于普通钻孔,但是在加工叠层材料时,超声振动并不能显著提高钻孔质量,这主要是由于钛合金切屑对复合材料层造成的撕裂损伤导致的。     

碳纤维复合材料钻孔加工的缺陷分析

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.     

高强有机纤维增强聚烯烃基复合材料加工技术

分析了纤维增强聚合物基复合材料的结构特点和力学性能，进行了高强有机纤维增强聚烯烃基复合材料的钻孔、开槽加工技术研究，提出了提高加工质量的技术途径，试验取得了较好的效果。     

碳纤维复合材料超声钻孔的研究

为碳纤维复合材料构件钻孔研制成一套旋转超声钻新技术。讨论了小型化超声振动系统的设计要点及试验分析；电流反馈式搜索电流最大值，超声波发生器的频率自动跟踪；轴向力约束型适应控制以及工具的等阻抗匹配。已将此超声振动钻孔系统制成便携式旋转超声钻，加工碳纤维复合材料效果良好。     

复合材料层压板钻孔分层激光超声检测方法

飞机复合材料结构钻孔分层的定位、定量检测是无损检测领域的难点之一,也是航空制造领域亟待解决的安全问题之一,激光超声检测技术是解决该问题的可能途径。试验验证利用激光超声检测复合材料钻孔分层的技术可行性。制备复合材料层压板钻孔试样,研究热弹性条件下脉冲激光在复合材料中产生超声波的宽频带特性,提取出满足检测灵敏度、分辨力要求并具有良好信噪比的超声信号;分析近孔边缘分层界面对声传播规律的影响,得出钻孔边缘分层缺陷的激光超声表征方法;采用脉冲反射法、透射法对复合材料钻孔试样进行激光超声C扫描检测,获得钻孔分层缺陷的形貌、尺寸和位置特征。研究结果表明,激光超声检测技术是解决飞机复合材料结构钻孔分层检测问题的有效手段。     

柔性复合材料钻孔技术

以芳纶纤维和高强聚乙烯纤维增强的聚合物基柔性复合材料为对象,针对这种柔性复合材料的结构和力学特性,分析了钻削柔性复合材料的特点和钻削孔产生缺陷的原因,并通过钻孔试验,在工艺装置,工艺参数,刀具材料及结构参数等方面研究了提高柔性复合材料钻孔质量的技术途径。     

基于ABAQUS的CFRP钻径向孔的轴向力研究

对碳纤维复合材料钻孔过程中,常常出现毛刺、撕裂、分层等缺陷。针对碳纤维增强树脂基复合材料钻径向孔质量差的问题,建立了碳纤维复合材料圆柱壳段钻径向孔的有限元模型,应用ABAQUS有限元软件对钻孔过程进行仿真,得到碳纤维复合材料钻径向孔时轴向力随切削用量的变化规律。     

一种用于金属/纤维增强复合材料加工仿真的动态有限元模型

以金属/纤维增强复合材料粘合板的钻孔加工为研究对象,提出了一种用于仿真加工过程的金属/纤维增强复合材料动态有限元模型。确定了金属、纤维复合材料和板件间胶合剂层的材料本构模型和动态损伤准则,并使用有限元软件ABAQUS实现了本构模型和准则的建立。通过用户子程序VUMAT建立纤维复合材料的模型和三维失效准则,实现对复合材料的三维应力应变分析,拓展了ABAQUS的功能。将该模型应用在具体分析实例中,进行了粘合板钻孔加工的数字仿真。使用不同加工参数对两种材料进行钻孔加工仿真,讨论加工参数对刀具轴向力和复合材料分层因子的影响。该模型可以用于粘合板的三维动态有限元仿真分析,为其加工研究提供了参考。     

超细颗粒增强铝基复合材料钻削性能研究

文中通过超细颗粒增强铝基复合材料钻孔试验,找出了钻削用量等因素对钻削力的影响规律,并用轴向力与扭矩的比值来表示铝基复合材料的钻削特性;基于钻削力考虑,高速钢钻头完全可以满足超细颗粒(≤0.5μm)增强铝基复合材料的钻孔要求。     

复合材料的激光钻孔新工艺

复合材料的激光钻孔新工艺复合材料具有强度高、重量轻的特点，在航空航天工业中得到广泛应用。但是，由于复合材料的硬度高、耐磨性好和组织结构的不均匀性，在切削中使切削力增大，刀具容易磨损。用磨损后的刀具切削时，工件容易产生分层，表面划伤以及进出口处产生大量...     

BTA深孔钻削EA4T钢的屑形研究

通过深孔钻床加工同批次空心车轴试验,研究错齿BTA深孔钻在不同切削参数(切削速度、进给量、切削液流量及压力)下的切屑形态对排屑效果的影响。由试验可知:当切削速度为80m/min、刀具进给量为0.2mm/r、切削液压力达到2.8MPa、切削液流量控制在90L/min时,加工后所产生的C形屑是深孔钻削排屑过程中的理想屑形。     

碳纤维复合材料/钛合金叠层钻孔质量研究

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。     

Ti6Al4V钛合金枪钻加工的切削力试验研究

钛合金在深孔加工过程中存在刀具磨损严重和加工表面质量差等问题。本文采用整体硬质合金单刃枪钻作为深孔加工刀具,通过对刀具结构的分析和对Ti6Al4V钛合金深孔钻削的切削力试验研究,得到工艺参数对切削力的影响规律,结合制孔的表面粗糙度,优化了钛合金枪钻加工工艺参数。同时,通过刀具的磨损分析得到了钛合金枪钻加工过程中刀具的主要磨损形式。     

基于径向力的可转位浅孔钻加工孔径误差研究

为研究可转位浅孔钻在切削过程中的钻孔孔径误差,基于可转位浅孔钻的理论几何模型,并利用经典斜切理论得到浅孔钻的径向力、力矩关于刀片几何参数和切削参数的计算公式。选取常用切削参数组合,将计算得的径向合力及力矩作为边界条件,通过ANSYS有限元分析刀体挠度,得出相关钻孔孔径误差的理论值。利用统计学回归方法建立相应数学模型,并通过切削试验验证数学模型的精确性。基于建立的数学模型,通过调节切削参数,可预测并控制孔径误差值,实现浅孔钻在半精加工中对孔径余量的精确控制,有效拓展可转位浅孔钻的应用范围。     

椭圆锥孔宏程序高效加工

主要介绍了椭圆锥孔宏程序的编写思路,以及如何通过修改参数来对切削层数进行控制,以达到最佳切削的效果。同时通过程序控制,使宏程序运行时机床能够按照指定的切削速度进行切削加工,避免无此功能控制时断续切削所产生的冲击力对机床传动系统造成的影响。     

Analysis of the machining characteristics in reaming AlSi12 alloy with PCD reamer

Machining characteristics were studied for the reaming AlSi12 alloy using six flutes polycrystalline diamond reamer on DMG DMU 50 linear five-axis CNC machine. The output measures for this experiment comprise of cutting torque, cutting thrust, hole diameter, hole cylindricity, and workpiece surface finishing. Cutting forces were in real time monitored by Kistler Dynamometer during the experiments. Hole diameter, hole cylindricity, and surface finishing (surface roughness and surface integrity) of the machined surfaces were measured after machining. It is indicated that the cutting force of thrust and torque decreased with increase of cutting speed and decrease of cutting feed. High accuracy of hole was achieved because the hole measurements satisfied the standard deviation. Hole diameters were within tighter tolerance value of 33₀ ^0.025, and cylindricalities varied in the range from 0.002 to 0.014 um (less than 0.02 um). As to surface finishing, high surface performance could be obtained by eliminating surface defects on initial hole such as cavities and voids after subsequent finishing operating of reaming. However, the reamed surface damages of AlSi112 alloy under inapposite cutting conditions were involved with re-deposited work material (chip), surface grooves and notch, feed marks, surface shrinkage cavities and porosities, metal debris, and micro-pits. Moreover, surface roughness improved with an increase in the cutting speed from 2,000 to 6,000 rpm, but it deteriorated evidently when the cutting speed increased from 6,000 to 10,000 rpm. Cutting speed of 6,000 rpm and cutting feed of 3,000 mm/min were the recommendable cutting parameters to ream AlSi12 alloy because best hole quality could be produced in comparison of other cutting parameters.     

CFRP/TC4叠层材料低频振动钻削试验研究

低频振动辅助切削技术是基于传统切削给刀具加上有规律并可控的振动,从而达到减小切削力、提高加工精度和延长刀具寿命的目的。将低频振动辅助切削技术应用到CFRP/钛合金叠层材料制孔中,在孔径、孔壁粗糙度和入口质量等制孔质量方面与传统钻削进行对比试验研究。结果表明,振动钻削在制孔质量上具有明显的优势。     

Surface topography and roughness in hole-making by helical milling

Helical milling is used to generate holes with a cutting tool traveling on a helical path into the workpiece in which the diameter of the hole can be adjusted through that of the helical path. Based on an improved Z-map model, a 3D surface topography simulation model is established to simulate the surface finish profile generated after a helical milling operation using a cylindrical end mill. The surface topography simulation model incorporates the effects of the relative motion between the cutting tool and the workpiece, in which the effect of the insert runout error of the cutting tool is considered. Furthermore, the roughness parameters are deduced from simulations of the 3D surface topography. The experimental result shows that the proposed simulation algorithm can predict well the surface roughness in a helical milling operation. The surface topography simulation model is used to study the effects of cutting conditions such as the tangential feedrate, the diameter of the cutting tool and the hole, the insert runout error of the cutting tool, as well as the revolution of the cutting tool around the axis of the hole on the surface finish profile. It is found that the surface quality can be improved by optimization of the cutting conditions. As a result, the proposed model will be helpful in determining the cutting conditions to meet surface finish requirements in helical milling operation.     

Laser hole cutting in Kevlar: modeling and quality assessment

Machining of Kevlar laminates with conventional methods results in poor end-product quality and excessive specific energy requirement for machining. However, laser machining has considerable advantages over the conventional methods due to precision and rapid processing. In the present study, laser hole cutting into Kevlar laminates with different thicknesses and properties is carried out. The laser output power, frequency, and cutting speed are varied during the hole-cutting experiments. The specific energy requirements for cutting, thermal efficiency of the cutting process, and kerf width are formulated and predicted for various laser parameters and Kevlar properties. The cut quality is associated with the damage size around the holes cut and statistical analysis is carried out to examine the affecting parameters on the damaged size. It is found that specific energy requirement is significantly lower than that of the conventional drilling method. The damage size is affected significantly by the laser irradiated power. The quality of holes, as judged by the percentage of damage size around the cut edges cut by a laser beam, is considerably improved compared to the conventional methods.     

Investigation on drilling-grinding of CFRP

It is difficult to machine polymer matrix composites reinforced by carbon fibre, and the holemaking process is the most necessary machining process for composite plate products. Conventional drills have a very short life in the drilling of this kind of composites and the quality of the hole is very poor. In this paper, the cemented or plated diamond core tools are tested to make holes in carbon fibre/epoxy composite plates. The effects of machining parameters, cooling and chip removal on the tool life, and the hole quality are investigated. The results indicate that the material removal mechanism of the two kinds of diamond tools is not like the cutting effect of the conventional drilling but similar to that of grinding. Satisfactory effects in making holes in the composites are obtained—quite acceptable machined hole quality, low costs, and long wear-resistant endurance.