碳纤维复合材料超声辅助钻削加工孔质量研究

碳纤维增强复合材料(carbon fiber reinforced plastics,CFRP)因其是编织材料,具有各向异性、强度高等特点,其加工难度大,加工质量较差.针对这一现状,采用电镀金刚石套料钻,对CFRP开展了超声辅助钻削与普通钻削对比实验,通过出入口质量、内壁形貌分析,研究了超声振动作用对孔出入口、内壁质量...     

碳纤维复合材料钻削孔分层缺陷的研究

采用氯化金渗透液对多向碳纤维复合材料钻削孔的分层缺陷进行了检测研究。总结出了钻孔分层缺陷的立体模型，指出孔的分层缺陷由入口侧分层和出口侧分层两部分组成，入口侧分层尺寸远远小于出口侧分层尺寸，入口侧分层为圆形，出口侧表面几层分层为椭圆形，深层分层仍为圆形。在此基础上，进一步对多向碳纤维复合材料板材钻削孔孔出口分层缺陷的大小与钻削参数间的关系进行了试验探索，得到一些有价值的试验数据和结论。     

碳纤维复合材料钻削孔分层影响分析

碳纤维复合材料(CFRP)的结构特点和特殊的物理性质,如各向异性、各向不均匀性和高比强度、高比硬度等,使其加工方式不同于金属加工。采用不同工艺参数及刀具几何参数对碳纤维复合材料进行钻削,分析出口和入口侧的撕裂分层影响,发现出口侧的撕裂情况优于入口侧的撕裂,各因素对出口侧和入口侧撕裂的显著性有所不同。     

碳纤维复合材料-钛合金层板钻孔质量研究

对比钻削碳纤维复合材料(CFRP),碳纤维复合材料-钛合金层板(CFRP-Ti),得出钻削CFRP-Ti时的CFRP入口分层、孔径误差、形状误差以及孔的表面粗糙度均比单独钻削CFRP时的要差.其原因是CFRP在上层,当钻削钛合金层时,一方面轴向钻削力大,钻削过程不平稳;另一方面钛合金的钻屑为螺旋长条状,这些都会影响已形成的孔壁.尤其在高转速下,此影响更为严重.     

基于微磁特性的球化质量电磁无损检测

针对传统转向节球化质量检测法存在时间长、效率低和操作复杂等问题,对基于初始磁导率法的球化质量无损检测系统进行了研究;通过对铁磁性材料微磁特性的分析,提出了一种基于初始磁导率的电磁无损检测方法;基于电磁场理论和基本方程组,建立了输出感应电压与激励源及磁路参数的数学方程,揭示了输出量与输入量之间的内在关联性;设计出了一套球化质量无损检测系统,对检测系统的电磁传感器、硬件电路及软件系统进行了分析,并将该检测系统应用于灰铸铁和球墨铸铁的实验测试。研究结果表明,灰铸铁测试值约为球墨铸铁测试值的70%;该方法能准确判断转向节是否合格,可实现转向节球化质量在线无损检测。     

Investigation on thrust force in rotary ultrasonic drilling of CFRP using Brad drill

Abstract

The carbon fiber reinforced plastic (CFRP) has been widely used in manufacturing industry due to its excellent mechanical and physical properties. Brad drill, as a representative of new-type structural drills, is applied in processing of CFRP. Meantime, rotary ultrasonic drilling (RUD) is regarded as a superior method for machining composite materials, due to its outstanding performance in lowering thrust force and improving processing quality. However, there are few reports about RUD with Brad drill in CFRP drilling. In this study, the theoretical model of thrust force for RUD of CFRP using Brad drill is developed. The dynamic uncut chip thickness and average uncut chip thickness in RUD are obtained based on kinematic characteristics analysis. After that, the structure of Brad drill is analyzed and thrust force of the cutting lip is molded. Then a theoretical model is proposed to predict the thrust force. Finally, pilot experiments are conducted for the model verification. Experimental results show that the trends of thrust force agree well with the thrust force model and the prediction error is less than 10%.     

An investigation of the hole machining processes on woven carbon-fiber reinforced polymers (CFRPs) using abrasive waterjets

An investigation of the hole cutting and drilling processes on woven carbon-fiber reinforced polymer sheets using abrasive waterjet (AWJ) is presented. The drilling process uses a stationary AWJ to impinge a target material to make a hole, while the cutting process requires an AWJ to penetrate the workpiece before moving in a circular path to cut a hole. It is found that the holes machined by both the processes exhibit similar geometrical features, where the diameter at the top is greater than at the bottom. It is further found that the holes from the drilling process have a better roundness than those from cutting process primarily due to the jet instability during cutting movement. Plausible trends of the hole characteristics (e.g., diameter and wall inclination) and defects (e.g., delamination) with respect to the process parameters are discussed. It is shown that water pressure is the major parameter affecting hole defects. The hole drilling process yields more severe defects than the cutting process because of the initial impact of the jet. Predictive models for machined hole diameter in both processes are developed. The model predictions are in good agreement with the experimental data under the corresponding conditions.     

平纹编织CFRP制孔分层形成机制的热-力学理论建模及试验分析

碳纤维增强复合材料(Carbon fiber reinforced plastics, CFRP)在航空航天领域获得了广泛应用,但由于各向异性和层间连接较差等特点,钻削过程中极易出现分层缺陷,严重影响构件的使用性能。为分析钻削温度对平纹编织CFRP制孔缺陷的影响机制,基于弹性地基梁理论、黏聚力学模型和热力学理论,建立了新钻型钻削平纹编织CFRP制孔分层形成的理论模型。结果表明：当新钻型多刃尖(Ⅲ)钻削孔边缘的最表层材料时,钻削温度达到最大值,对最终分层的形成最为关键;钻削温度和制孔分层随着主轴转速的增大而逐渐降低,随着进给速度的增大而逐渐升高。当纤维角度(θ)在0°/90°/180°/270°附近时,层间分层的临界轴向力达到最大值,分层相对较大,当纤维角度(θ)在45°/135°/225°/315°附近时,临界轴向力最小,分层并非极大。因此,临界力的大小只能反映产生分层缺陷的难易程度,不能决定分层的最终形状和大小。考虑温度影响时的制孔分层形态预测与试验观测基本吻合,而不考虑温度影响下所获得的预测值总体上偏小。此外,平纹编织CFRP分层形状基本呈近似圆形。     

高模量碳纤维复合材料钻削力和加工缺陷分析

由于碳纤维复合材料独特的物理结构和化学性质,在其钻削加工中往往容易出现撕裂、毛刺、分层等缺陷,而这些缺陷与钻削参数以及钻削力息息相关。采用全因素实验研究了切削速度和进给速度对切削力以及钻削加工缺陷的影响。利用方差分析,对切削速度和进给量对实验结果的影响程度进行了分析。研究发现进给量是影响钻削加工最主要的因素,并且钻削轴向力和加工缺陷随切削参数的变化趋势基本一致。     

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。     

基于统一数据源的协同无损检测管理系统设计与研究

针对航天制造企业无损检测业务过程管理技术薄弱,缺乏信息化手段支撑问题,提出一种基于统一数据源的协同无损检测管理系统.对系统功能框架与运行流程进行设计,并研究系统实现的3项关键技术:基于统一数据源的无损检测业务过程信息继承机制、交互式检验任务委托与检验结果监控推送技术、检验对象自动编码技术.基于设计思想构建协同无损检测过程管理原型系统,结合企业实际检测业务需要,对系统实现的合理性与适用性进行验证.     

Experimental characterization and finite element modeling of critical thrust force in cfrp drilling

Composite laminates are used in many applications in ae-rospace/defense industries due to their high strength-to-weight ratio and corrosion resistance properties. In general, composite materials are hard-to-machine materials which exhibit low drilling efficiency and drilling-induced delamination damage at exit. Hence, it is important to understand the drilling processes for composite materials. This article presents a comprehensive study involving experimental characterization of drilling process to understand the cutting mechanism and relative effect of cutting parameters on delamination during drilling of carbon fiber reinforced plastic (CFRP). Thrust force and torque data are acquired for analyzing the cutting mechanism, initiation and propagation of delamination, and identification of critical thrust force below which no damage occurs. An FE model for prediction of critical thrust force has been developed and validated with experimental results. A [0/90] composite laminate is modeled simulating the last two plies in exit condition and a thin interface layer is inserted in between the plies to capture delamination extent. The tool geometry is modeled as “rigid body” with geometric features of twist drill used in experiments. The tool is indented on the workpiece to simulated tool feeding action into the workpiece. The FE model predicts the critical thrust force within 5% of the experimentally determined mean value.     

钛合金螺旋铣孔与传统钻孔的加工质量对比

对钛合金进行了螺旋铣孔与传统钻孔试验,研究了两种孔的加工质量及影响因素。结果表明:钛合金螺旋铣孔的质量相对较高,表面粗糙度相对较小;对于螺旋铣孔工艺,轴向每转进给量是影响孔表面粗糙度的主要因素,切向每齿进给量是影响孔圆度的主要因素,螺旋铣孔参数对孔径的影响不大;对于传统钻孔工艺,轴向每转进给量是影响孔表面粗糙度、圆度和孔径的主要因素。     

C/C-SiC复合材料钻削加工工艺研究

通过采用钎焊金刚石钻头对C/C-SiC复合材料进行钻削试验,借助测力仪、超景深显微镜等手段,研究钻削参数对钻削过程中钻削力及孔出入口质量的影响规律。试验结果表明,在钻削C/C-SiC复合材料时,钻削力随着进给量的增加而增大,随着转速的增加而减小,且进给量对钻削力的影响大于主轴转速的影响。     

Comparative tool wear and hole quality investigation in drilling of aerospace grade T800 CFRP using different external cooling lubricants

The International Journal of Advanced Manufacturing Technology - The T800 Carbon fiber reinforced polymer/plastic (CFRP) has been increasingly used for its considerable specific strength/modules to...     

Application and evaluation of optical distance measurements in geometrical quality testing of microgears

Microgears are increasingly important in industry. Compared to normal gears, the quality assurance of microgears needs more accurately measured data and simple but feasible measurement methods because of their dimension particula     

The defect detection and non-destructive evaluation in weld zone of austenitic stainless steel 304 using neural network-ultrasonic wave

In recent years, the importance of non-destructive evaluation has rapidly increased due to the collapse of large structures and the shooting up of safety accidents. The ultrasonic method. which is often used as a major non-destructive testing (NDT) technique in many engineering fields, is playing a significant role as a volumetric test regarded highly for evaluating a material’s integrity. This paper is recommended for publication the detecting any defects of the weld zone in austenitic stainless steel type 304 using ultrasonic waves, employing neural network on the basis of the detected defects and evaluating them. In detecting defects, we drew a distance amplitude curve on a standard scan sensitivity and a preliminary scan sensitivity shown in the correlation between the ultrasonic probe, the instrument and the materials on a quantitative standard, and quantitative evaluation is used to draw a distance amplitude curve. A total of 93. 3% of the defect types was distinguished by testing 30 defects after organizing a neural network system based on the defects on the ultrasonic evaluation and learning the neural network system. Thus the proposed ultrasonic wave-neural network in this work is useful for defects detection and Ultrasonic Non-Destructive Evaluation (UNDE) of the weld zone of austenitic stainless steel 304.     

Quantitative evaluation method and formation mechanisms of entrance chipping in rotary ultrasonic drilling of glass BK7

Abstract

This investigation presented a quantitative evaluation technique of the hole entrance chippings with respect to the image processing technology. Considering the nucleation and propagation processes of lateral cracks, the chipping formation mechanisms involved in rotary ultrasonic drilling of glass BK7 were also explored incorporated with the abrasive kinematics and the fracture mechanics of brittle material. As a result, it was revealed that each individual chipping represented a smooth appearance at the chipping inside, and the instantaneous nature of the lateral crack formation process was responsible for this damage feature. Moreover, the friction effects between the abrasive and the material caused the lateral crack suffering from the extra torsional moment, resulting in the scattered fracture stripes on the chipping outside. A novel evaluation method of hole entrance quality, founded on the pixel rate of the chipping area to hole perimeter, was proposed, which could provide a more accurate measurement by considering the comprehensive effects of all chippings on the entrance quality. The increased rotation speed of the tool prolonged the plastic deformation region in the interior material along the abrasive scratching direction, severely deteriorating the entrance quality of the drilled hole.