碳纤维复合材料-钛合金叠层板钻孔工艺研究

通过单因素试验方法,开展钻削碳纤维复合材料-钛合金叠层板(CFRP-Ti)的试验研究,研究不同钻削参数对钻削CFRP-Ti的轴向力和孔加工质量的影响,并对比了两种不同钻尖结构的钻头之间的钻孔差异。试验结果表明:轴向力随进给量的增大而增大,而随转速的增大小幅减小。随着进给量的增大,CFRP退钻口撕裂因子逐渐增大,进钻口撕裂因子也呈现逐渐小幅增大的趋势;Ti合金进钻口孔质量高、缺陷少,而退钻口翻边则越来越严重。在不同转速条件下,CFRP进钻口及退钻口孔质量较高,但在高转速时,退钻口可观察到高温灼伤;随着转速的增大,Ti合金孔退钻口翻边呈先减小,再增大的现象。采用两种不同钻尖结构的钻头对CFRP-Ti进行钻削对比试验,结果显示,"烛台钻‘钻孔质量有明显优势。     

钎焊金刚石套料钻钻削CFRP的孔质量研究

采用钎焊金刚石套料钻进行了钻削碳纤维增强树脂基复合材料(CFRP)试验,使用测力仪与三维视频显微镜对钻削过程中的钻削力以及孔出、入口缺陷进行了测试与观察.实验结果表明:钎焊金刚石套料钻钻削CFRP时,相同转速下,钻削力随进给量的增大而增大;相同进给量下,钻削力随转速的增大而增大,且进给量对钻削力的影响大于转速的影响;已...     

钻削参数对碳纤维复合材料孔加工质量的影响

本研究通过单因素试验方法,开展钻削碳纤维复合材料的试验研究。采用KISTALER公司9265B型测力仪测钻削轴向力,并采用撕裂因子评价孔形貌质量,对钻削碳纤维复合材料的过程进行分析,研究不同钻削参数对钻削碳纤维复合材料的轴向力和孔加工质量的影响。试验结果表明:随着进给量的增大,轴向力逐渐增大,孔退钻口撕裂因子呈现先减小再增大的趋势,孔进钻口撕裂因子则呈现逐步小幅增大的趋势。随着转速的增大,轴向力逐步小幅减小,孔退钻口撕裂因子随之减小。并且,进给量对轴向力和孔加工质量的影响远大于转速对轴向力和孔加工质量的影响。在相同条件下,孔进钻口的毛刺、撕裂等缺陷明显少于退钻口的缺陷。     

钎焊金刚石磨粒钻钻削C/SiC陶瓷基复合材料孔时切屑对钻削过程的影响

钎焊金刚石磨粒钻适合钻削碳纤维增强碳化硅陶瓷基复合材料孔,但大量切屑会对孔的钻削过程产生不利影响。为此,针对切屑排出过程,分析切屑形貌,研究钻削时切屑对轴向钻削力、孔加工质量、钻头磨损的影响。结果表明：切屑对轴向钻削力有影响,尤其钻削深孔时影响显著。切屑对孔进口的加工质量几乎没有影响,只表现为孔进口处的轻微崩边;切屑对孔出口的加工质量影响显著,可引起严重的纤维断裂、撕裂缺陷以及基体的大区域脱落。同时,切屑加剧钻头磨损,使钻头不仅出现崩刃、微裂纹等轻微磨损,而且还产生基体剥落、金刚石剥落等严重磨损行为。     

不同粒度的金刚石套料钻钻削碳纤维复合材料时对轴向力及出入口质量的影响

碳纤维增强复合材料在加工过程中,容易产生分层、毛刺、撕裂等缺陷,还会加剧刀具的磨损。针对以上问题,研制了不同粒度的金刚石套料钻,进行了碳纤维复合材料制孔加工实验,分析了磨粒粒度对轴向力、扭矩和出口质量的影响。得到以下结论:采用有细粒度金刚石的钎焊套料钻可以减小钻孔时的轴向力和扭矩。不同粒度套料钻所加工的孔入口处均未出现任何缺陷,出口处的缺陷主要以撕裂缺陷为主。金刚石粒度80/100的钎焊套料钻在进给速度为100 mm/min,主轴转速15 000 r/min的条件下出入口质量优于其他粒度。     

GFRP低频轴向振动制孔的钻削力特性和套料钻磨损分析

GFRP的套孔钻削过程中极易产生分层、撕裂等加工损伤,其与轴向钻削力直接相关。为提高GFRP的制孔质量,采用新型金刚石薄壁套料钻,结合低频轴向振动加工技术,建立单颗磨粒的运动学模型和动力学模型,试验研究GFRP制孔中的轴向力变化规律,并对套料钻的烧焦概率、自动落料率进行分析。结果表明：对比常规钻削,低频振动钻削时的瞬时进给量和轴向力比常规钻削时的大,且随着振幅的增加,轴向力也随之增大;低频振动钻削和常规钻削时的轴向力皆随进给速度的增加而增大,随主轴转速的升高而降低。同时,低频振动钻削时磨粒间断性地参与钻削,大大降低了套料钻的烧焦概率,提高了其自动落料率,自动落料率高达88.24%,可实现GFRP的连续批量制孔。     

C/SiC复合材料微孔的电镀金刚石钻头钻削加工

用金刚石基本颗粒尺寸分别为20～30,36～54和63～75μm,直径在0.280～0.440 mm范围的6种电镀金刚石钻头,钻削三维针刺毡基C/SiC复合材料微孔,测试6种钻头的最佳加工工艺参数,分析工艺参数及金刚石基本颗粒尺寸、钻头直径等对微孔加工质量、加工效率的影响。结果表明：在相同钻削速度条件下,进给速度越低时,加工的微孔质量越好;钻头电镀的金刚石磨粒基本颗粒尺寸越大,其钻削效率越高;在6种钻头中,直径为0.300 mm的基体上电镀63～75μm的磨粒,直径为0.200 mm的基体上电镀36～54μm的磨粒,能够获得更优的钻孔性能。     

钎焊金刚石薄壁钻加工工程陶瓷的试验研究

通过用钎焊金刚石薄壁钻加工Al2O3工程陶瓷的钻削试验，测量和分析了在不同加工参数下钻削轴向力和扭矩的变化，并与电镀钻头的加工性能进行了对比。结果表明，用钎焊金刚石薄壁钻加工工程陶瓷材料的设想可行，与电镀钻头相比，钎焊钻头钻削过程更稳定，加工质量更好，尤其在高转速、大进给加工条件下具有明显优势。     

夹层结构复合材料钻削试验研究

选用φ12mm高速钢麻花钻,在干切削条件下对夹层结构复合材料进行单因素钻削试验,研究钻削参数的变化对钻削轴向力的影响规律以及出口垫板对分层的影响;选用聚晶金刚石钻头,通过与高速钢麻花钻比较,研究横刃对轴向力以及分层的影响。结果表明:小进给量情况下,选择横刃小的钻头进行钻削,可以提高孔出口的加工质量。     

氧化锆陶瓷微孔钻削加工工艺试验研究

针对氧化锆陶瓷钻削微孔过程中出现的轴向力大和出口崩边严重的问题，使用直径为0.2 mm的金刚石涂层钻头钻削完全烧结的氧化锆陶瓷微孔，通过单因素试验方法，研究主轴转速、进给速度和步进距离对轴向力的影响，在此基础上开展啄钻工艺对比试验，探索变进给啄钻工艺对出口崩边尺寸的影响。结果表明：轴向力大小随着进给速度和步进距离的增加而增大，随着主轴转速的增加先降低后增大；采用变进给啄钻可以有效提高孔出口加工质量。     

Drilling thick fabric woven CFRP laminates with double point angle drills

Carbon fiber reinforced plastics (CFRPs) have many desirable properties, including high strength-to-weight ratio, high stiffness-to-weight ratio, high corrosion resistance, and low thermal expansion. These properties make CFRP suitable for use in structural components for aerospace applications. Drilling is the most common machining process applied to CFRP laminates, and it is difficult due to the extremely abrasive nature of the carbon fibers and low thermal conductivity of CFRP. It is a challenge for manufacturers to drill CFRP materials without causing any delamination on the work part while also considering the economics of the process. The subject of this study is the drilling of fabric woven type CFRP laminates which are known to be more resistant to delamination than unidirectional type CFRP laminates. The objective of this study is to investigate the influence of double point angle drill geometry on drilling performance through an experimental approach. An uncoated carbide and two diamond coated carbide drills with different drill tip angles are employed in drilling experiments of aerospace quality thick fabric woven CFRP laminates. Force and torque measurements are used to investigate appropriate drilling conditions based on drill geometry and ideal drilling parameters are determined. Tool life tests of the drills were conducted and the condition of the diamond coating is examined as a function of drilling operational parameters. High feed rate drilling experiments are observed to be favorable in terms of drill wear. Feed is observed to be more important than speed, and the upper limit of feed is dictated by the drill design and the rigidity of the machine drill. Hole diameter variation due to drill wear is monitored to determine drill life. At high feeds, hole diameter tolerance is observed to be more critical than hole exit delamination during drilling of fabric woven CFRP laminates.     

Feasibility study of the rotary ultrasonic elliptical machining of carbon fiber reinforced plastics (CFRP)

Carbon fiber reinforced plastics (CFRP) are used for various aircraft structural components because of their superior mechanical and physical properties such as high specific strength, high specific stiffness, etc. However, when CFRP are machined, rapid tool wear and delamination are troublesome. Therefore, cost effective and excellent quality machining of CFRP remains a challenge. In this paper, the rotary ultrasonic elliptical machining (RUEM) using core drill is proposed for drilling of holes on CFRP panels. This method combines advantages of core-drill and elliptical tool vibration towards achieving better quality, delamination free holes. The cutting force model and chip-removal phenomenon in ultrasonic elliptical vibration cutting are introduced and analyzed. The feasibility to machine CFRP for RUEM is verified experimentally. The results demonstrate that compared to conventional drilling (CD), the chip-removal rate has been improved, tool wear is reduced, precision and surface quality around holes is enhanced, delamination at hole exits has been prevented and significant reduction in cutting force has been achieved.     

A mechanistic approach to investigate drilling of UD-CFRP laminates with PCD drills

Carbon fiber reinforced plastics (CFRPs) possess desirable material properties that satisfy the aerospace industry's high strength to weight ratio objective. Therefore, CFRPs are commonly used in structural parts, either alone or together with aluminum and titanium alloys. Drilling of CFRPs has been studied extensively in the literature in recent years, with special emphasis on process parameters and delamination. This study identifies mechanical properties of uni-directional CFRPs through drilling tests. Drilling of uni-directional CFRP plates with and without pilot holes has been performed, and cutting and edge force coefficients are identified. A polycrystalline diamond (PCD) drill was used in tests since this type of drill is commonly used in practice. Finally, validation tests on multi directional CFRP laminates have been performed and good results have been obtained.     

碳纤维复合材料旋转超声椭圆振动套磨制孔技术研究

针对航空航天领域中碳纤维复合材料在制孔过程中易出现分层、毛刺和刀具磨损快等问题,提出了一种新型旋转超声椭圆振动套磨制孔技术。分析了旋转超声椭圆振动套磨制孔机理,研制出了小型化旋转超声椭圆振动套磨制孔系统,并进行了碳纤维复合材料(CFRP)套磨制孔实验。结果表明:相比于普通套磨,超声椭圆振动套磨极大改善了切屑粉尘和料芯的排出,延长了刀具使用寿命;明显降低了钻削力和扭矩分别约25%和30%;有效降低了复材孔分层和毛刺的制孔缺陷,改善了孔表面粗糙度和平整性,提高了加工质量。     

A machine tool motorized spindle with hybrid structure of steel and carbon fiber composite

Carbon fiber reinforced plastic (CFRP) is a promising material for enhancing the spindle performance of machine tools because of its high specific stiffness and low thermal expansion. However, when a conventional steel spindle shaft is replaced by a CFRP shaft, the anisotropic property of CFRP makes it difficult to maintain the static stiffness that is equivalent to that of conventional spindles. This study proposes a hybrid structure of steel and CFRP to avoid reduced stiffness of the shaft. Fundamentals of shaft design are described to enable discussion of a favorable steel-CFRP ratio. An experimental evaluation of a developed CFRP spindle is also reported.     

Evaluation of the total cutting force in drilling of CFRP: a novel experimental method for the analysis of the cutting mechanism

The CFRP drilling process has not yet been fully mastered, which is due to the fact that it is not possible to measure all the cutting force components. In order to gain new insights into the drilling process, a novel experimental setup is being developed in order to record all cutting force components (cutting force, feed force, passive force). The results show that the force components are strongly dependent on the fiber cutting angle θ and the wear condition. Thereby, it will be possible to draw conclusions about the cutting mechanics in the drilling of unidirectional CFRP based on the transformation of the forces perpendicular and parallel to the fiber.     

钻孔过程中切削温度对CFRP亚表面的影响

研究了碳纤维增强聚合物(CFRP)/Ti叠层构件钻孔时切削温度对钻孔质量的影响,分析了有无钛合金支撑层制孔时CFRP的切削力、切削热、孔壁表面和亚表面质量,并提出了亚表面损伤评价方法。结果表明,钻孔时钛合金支撑层对CFRP切削力及表面质量的影响较小,但对切削温度和亚表面质量影响显著。刀具同时加工钛合金和CFRP时会产生大量切削热,导致CFRP孔出口处温度大幅升高,高温导致CFRP树脂基体的刚度和粘结性能下降,使得CFRP孔出口附近纤维层上出现了严重的亚表面损伤。同时,采用提出的亚表面损伤评价方法对亚表面损伤进行评价,发现靠近出口处的纤维层亚表面损伤最为严重。在远离出口平面的方向上,亚表面损伤程度逐渐降低。因此,CFRP/Ti叠层构件钻孔过程中切削温度显著影响CFRP孔的亚表面质量,且亚表面的损伤程度是评价CFRP加工质量的重要因素。     

Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates

In this paper, a concept of delamination factor F_d (i.e. the ratio of the maximum diameter D_max in the damage zone to the hole diameter D) is proposed to analyze and compare easily the delamination degree in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. Experiments were performed to investigate the variations of cutting forces with or without onset of delamination during the drilling operations. The effects of tool geometry and drilling parameters on cutting force variations in CFRP composite materials drilling were also experimentally examined. The experimental results show that the delamination-free drilling processes may be obtained by the proper selections of tool geometry and drilling parameters. The effects of drilling parameters and tool wear on delamination factor are also presented and discussed.Cutting temperature has long been recognized as an important factor influencing the tool wear rate and tool life. An experimental investigation of flank surface temperatures is also presented in this paper. Experimental results indicated that the flank surface temperatures increase with increasing cutting speed but decreasing feed rate. Optimal cutting conditions are proposed to avoid damage from burning during the drilling processes.     

An additive manufacturing-based approach for carbon fiber reinforced polymer recycling

The vast Carbon Fiber Reinforced Polymer (CFRP) waste accumulated is pressing for its recycling. A novel recycling approach, which integrated carbon fiber reclamation and composite additive manufacturing, is proposed to process the CFRP waste into three Dimensional (3D) parts. In the experiments, the CFRP waste was recycled by supercritical n-butanol to yield reclaimed Carbon Fibers (rCFs). The rCFs were ground by a ball mill, mixed with Poly-Ether-Ether-Ketone (PEEK) powder and then extruded to the composite filament. The filament was fed to the Fused Deposition Modeling (FDM) printer to fabricate 3D parts. Mechanical and electrical properties of the parts were investigated and compared with that of pure PEEK. The results illustrate that the additive manufacturing-based approach offers a potential strategy to reuse the CFRP waste and rapidly fabricate the rCF reinforced plastics with complex geometry and function.