篦齿盘高敏感孔螺旋铣加工工艺研究

研究了GH4065A粉末高温合金篦齿盘高敏感孔螺旋铣削加工工艺,通过试验摸索出螺旋铣削粉末高温合金异形孔的加工工艺参数,实现了螺旋铣削加工工艺代替传统磨粒流加工的目的。通过对篦齿盘零件材料及工艺结构特点、加工难点的分析,结合高敏感孔加工工艺过程控制要求,采用试验方法,开展切削工艺参数的试验。粗加工过程采用钻削加工方式,主轴转速S=350 r/min,进给量F=0.05 mm/r。一把钻头加工18个孔后,刀具磨损量达到0.191 mm,接近技术要求规定的钻头最大磨损带不超过0.20 mm的上限要求;精加工过程采用?2.8×R0.8四刃端面铣刀,利用端面铣刀刀尖R作为切削刃进行螺旋铣削,并开展铣削过程扭矩监控,主轴转速S=1 700 r/min,进给量F=0.05 mm/r,每层切削深度为0.15 mm,之后进行孔口倒角铣削及孔口毛刷去毛刺加工。通过检测,异形孔加工尺寸满足要求,表面粗糙度达到Ra1.6μm,所有技术指标均满足图样要求。     

K24镍基高温合金切削性能试验研究

针对K24铸造镍基高温合金的特点,设计了合理的正交切削试验方案,通过铣削和钻削试验研究了K24高温合金的切削力、表面加工质量和刀具磨损等方面的切削性能,并给出了铣削力、钻削力和转矩的经验公式.研究工作对该材料加工过程中的切削用量、冷却液和刀具几何参数等的选择具有指导和参考意义.     

CFRP/Ti叠层材料螺旋铣孔与钻孔的刀具磨损对比与分析

针对螺旋铣孔与传统钻孔刀具磨损的问题,对CFRP/Ti叠层材料进行螺旋铣孔与传统钻孔试验。在相同加工效率及切削速度的基础上,对两种工艺加工孔的切削力及刀具后刀面磨损长度进行了测量。结果表明:制孔过程中,螺旋铣削制孔的切削力明显小于钻削制孔的切削力;加工过程中,螺旋铣削制孔的切削力比钻削制孔的切削力更加平缓;同等参数条件下,螺旋铣削加工到24孔时刀具失效,传统钻削加工到18孔时刀具失效;螺旋铣削制孔的刀具比钻削制孔的刀具更加耐磨,加工孔数更多。     

K465铸造高温合金材料铣削加工技术

K465材料是一种合金化程度高、具有高热强性的镍基铸造高温合金,可在1000℃～1050℃高温状态长时间工作,能满足航空航天领域对材料承温能力的要求。目前对K465材料的铸造工艺和热处理工艺的研究较多,而对其切削加工性能的研究较少。针对K465铸造高温合金材料,探讨了其切削加工性能,进行了刀具匹配性选择,通过铣削试验研究了铣削参数对刀具寿命的影响规律,总结优化了铣削参数和切削加工路径,为K465铸造高温合金材料的高效高质加工提供了理论基础。     

K477镍基高温合金切削加工预测模型的建立及切削参数优化

针对航空发动机制造对新型镍基高温合金K477切削加工工艺的需求,结合K477的性能特点,设计了均匀试验规划方案,通过试验和切削模型分析研究了K477的铣削及钻削可加工性。首先建立了切削力、刀具磨损和切削温度等预测模型,给出了切削参数与切削力、刀具磨损量以及切削温度之间的量化关系,并研究了刀具磨损机理,最后采用遗传算法以切削效率为目标,以刀具磨损量为约束对切削参数进行了优化。研究结论对于解决航空发动机零件所需新材料的工程制造具有重要的指导意义。     

GH4065A涡轮盘榫槽型面拉削加工变形研究

GH4065A高温合金是通过铸—锻工艺制备的镍基变形高温合金，在700℃以上温度使用时具有与第二代粉末冶金涡轮盘相同的力学性能，适用于新一代航空发动机涡轮盘的制造。在某型GH4065A高温合金涡轮盘榫槽的拉削加工中，存在变形量高达0.1mm以上的情况，导致榫槽型面不合格。针对此问题，分析了导致榫槽型面变形的原因和榫槽不同区域的切削力大小，提出控制变形的解决方案，修正了用于高温合金拉削力计算公式中的C_p及x参数。     

基于响应曲面法的GH4169镍基高温合金干车削参数优化试验

GH4169镍基高温合金具有优异的高温强度、塑性、耐腐蚀性和抗疲劳性能,广泛应用于制造航空发动机、燃气轮机的涡轮叶片等高温部件,而其热导率低、导热性差、加工硬化倾向大,是典型的难加工材料。采用正交试验法和响应曲面法,研究了涂层硬质合金刀具干式车削GH4169镍基高温合金的切削力和已加工表面粗糙度。通过正交实验研究了加工参数对切削力和已加工表面粗糙度的影响;通过回归分析建立了加工参数与切削力、已加工表面粗糙度的回归方程,并揭示了切削力、表面粗糙度与切削参数的响应关系;基于正交试验数据,通过多目标规划,优化得到了涂层刀具车削加工GH4169镍基高温合金的切削参数。     

基于ABAQUS的刀具几何参数对铣削HT250铸铁变截面涡旋盘的影响

由于变截面涡旋盘加工比较复杂,且加工精度要求高,需考虑刀具几何参数。开展HT250铸铁变截面涡旋盘高速铣削仿真,研究刀具几何参数对其的影响,并通过试验加工出变截面涡旋盘实体;构建由三段基圆渐开线组成的变截面涡旋盘数学模型,建立三维铣削模型和简化后的二维铣削模型,基于ABAQUS软件分析加工时刀具前角、后角和钝圆半径对铣削力和铣削温度的影响规律,得到不同刀具几何参数的铣削应力云图和铣削温度分布云图。通过刀具几何参数对变截面涡旋盘铣削力和铣削温度影响规律的研究,为选择合理的刀具几何参数提供依据和参考,便于提高变截面涡旋盘加工精度。     

微铣削单晶高温合金刀具磨损实验研究

为研究微小刃径刀具切削难加工材料后刀具的磨损,针对单晶镍基高温合金材料的难加工特性,设计了单因素实验方案,采用直径为0.6 mm的硬质合金微小刃径刀具对单晶镍基高温合金DD98进行微铣削加工;通过磨损后的刀具直径和铣削槽底宽度尺寸的变化来定义微铣削刀具(微小刃径刀具)切削加工的磨损标准,建立了微铣削刀具磨损标准的数学模型;基于单因素实验方案,探讨了不同切削参数条件下,微铣削长度对刀具磨损量的影响.相关研究和实验数据对于探索难加工材料的切削机理具有理论指导意义.     

微铣削单晶高温合金刀具磨损实验研究

为研究微小刃径刀具切削难加工材料后刀具的磨损,针对单晶镍基高温合金材料的难加工特性,设计了单因素实验方案,采用直径为0.6 mm的硬质合金微小刃径刀具对单晶镍基高温合金DD98进行微铣削加工;通过磨损后的刀具直径和铣削槽底宽度尺寸的变化来定义微铣削刀具(微小刃径刀具)切削加工的磨损标准,建立了微铣削刀具磨损标准的数学模型;基于单因素实验方案,探讨了不同切削参数条件下,微铣削长度对刀具磨损量的影响.相关研究和实验数据对于探索难加工材料的切削机理具有理论指导意义.     

HOLE MAKING USING BALL HELICAL MILLING ON TITANIUM ALLOYS

In this article, results of helical ball milling for hole making on Ti-6Al-4V alloy are presented and compared with drilling. Two different machining strategies were tested with a ball end mill. In the first strategy only a helical milling path was used to achieve the nominal diameter. The second strategy has two stages; first, helical milling considering a diameter 50 µm below the nominal, and second, the tool flank of the ball end mill were used to remove the stock left with a single contouring operation. Experimental tests were performed taking into account the process time, final quality of holes, hole diameter, roughness and burr formation at tool entrance and exit. With helical milling two advantages were concluded: the process is versatile because one tool is suitable for a range of diameters and negligible burrs are produced. However hardness in the zones close to hole internal surfaces machined with the ball end mill tool decreases with respect to twist drilling. The information obtained from this research work defines suitable cutting parameters for the helical milling process in the titanium alloy Ti-6Al-4V with ball end mills.     

高速铣削镍基合金GH4169切削力的试验研究

镍基合金广泛应用于航空航天上,但加工起来比较困难。文中以镍基合金GH4169为试验对象,进行了高速铣削试验,研究铣削速度vc、轴向切深ap、径向切宽ae和进给量f四个切削参数对切削力F的影响,从而为生产实践提供指导。     

CFRP及叠层结构螺旋铣孔专用刀具切削性能评价

碳纤维增强复合材料(CFRP)及由钛合金Ti-6Al-4V和CFRP组成的金属复合材料叠层结构广泛应用于现代航空工业。大型客机结构件之间主要通过铆接和高锁螺栓连接,根据波音与空客公司发布的数据显示,最新一代B787与A380上装配孔的数量已超百万,装配过程中的制孔效率与质量直接决定了客机整体装配效率及关键结构件的疲劳寿命,从而间接影响了客机的生产成本以及飞行可靠性。随着飞机数字化装配的快速发展,传统的钻孔工艺会产生很多加工缺陷,工序复杂,加工孔质量不能满足要求,因此,有必要优化制孔工艺,设计新型专用刀具。本文通过研究螺旋铣孔运动学特性,分析螺旋铣孔的工艺特点,设计了一种新型螺旋铣孔专用刀具,并以加工过程的轴向切削力、出入口加工质量以及刀具磨损为评价指标,验证该新型专用刀具的切削性能。结果表明,专用刀具在干切削条件下能够实现复材孔无分层、钛合金孔无毛刺加工,大幅提高刀具寿命,解决了传统立铣刀对CFRP及CFRP/钛合金叠层结构进行螺旋铣孔时刀具寿命低、加工质量差等问题。     

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.     

Influence of thermal mechanical coupling on surface integrity in disc milling grooving of titanium alloy

Disc milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on the difficult-to-cut material. The processing efficiency of machined components thus can be tremendously improved with the application of disc milling. However, the fundamental research of the mechanisms of disc milling on cutting metal materials, especially on titanium alloys, is lacking in the literature. In this study, the milling force and temperature were inspected in disc milling grooving experiment, and the effect of thermal-mechanical coupling on surface integrity of titanium alloy, including surface roughness, surface topography, surface and subsurface residual stress, microstructure, and microhardness, was analyzed. The results showed that a better surface quality can be obtained at the center of the surfaces compared to the marginal regions on the same machined surface. Residual compressive stress was generated on the machined surface and subsurface and gradually reduced to zero with an increase in depth. The microstructure of lattice tensile deformation was emerged along feed direction, while the phase transition was not produced. A hardened layer was found on the machined surface and subsurface, mostly causing by the mechanical loads and oxidation reaction.     

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.     

飞机壁板柔性装配螺旋铣孔单元的研制

针对现代飞机壁板高效精密制孔的需求,研制一种面向大型航空组件柔性装配的新型螺旋铣孔单元。首先,通过对国内外现有机身自动制孔系统的技术分析,并结合壁板装配制孔的作业特点,引入一种新兴的制孔技术——螺旋铣孔。其次,对螺旋铣孔运动进行功能分解,展开了螺旋铣孔单元的模块化设计,确定了偏心调节模块的传动方案,设计了铣刀结构与装夹方式。最后,基于螺旋铣孔单元样机,对航空铝合金和碳纤维复合材料进行了切削试验,结果表明铣孔质量基本满足飞机装配的精度要求。     

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。     

Enhancement and verification of a machined surface quality for glass milling operation using CBN grinding tool—Taguchi approach

Nowadays, the demand for high product quality focuses extensive attention to the quality of machined surface. The (CNC) milling machine facilities provides a wide variety of parameters set-up, making the machining process on the glass excellent in manufacturing complicated special products compared with other machining processes. However, the application of grinding process on the CNC milling machine could be an ideal solution to improve the product quality, but adopting the right machining parameters is required. Taguchi optimization method was used to estimate optimum machining parameters with standard orthogonal array L₁₆ (4⁴) to replace the conventional trial and error method as it is time-consuming. Moreover, analyses on surface roughness and cutting force are applied which are partial determinant of the quality of surface and cutting process. These analyses are conducted using signal to noise (S/N) response analysis and the analysis of variance (Pareto ANOVA) to determine which process parameters are statistically significant. In glass milling operation, several machining parameters are considered to be significant in affecting surface roughness and cutting forces. These parameters include the lubrication pressure, spindle speed, feed rate, and depth of cut as control factors. While, the lubrication direction is considered as a noise factor in the experiments. Finally, verification tests are carried out to investigate the improvement of the optimization. The results showed an improvement of 49.02% and 26.28% in the surface roughness and cutting force performance, respectively.     

An investigation of optimum SiO2 nanolubrication parameters in end milling of aerospace Al6061-T6 alloy

Aluminium AL6061-T6 is a common alloy which is used for many purposes since it has the superior mechanical properties such as hardness and weldability. It is commonly used in aircraft, automotive and packaging food industries. Milling of Al6061-T6 would be a good process especially in producing varieties shape of products to adapt with different applications. The capability of the CNC milling machine to make batch production would be a noteworthy advantage. However, the demand for high quality focuses attention on product quality, especially the roughness of the machined surface, because of its effect on product appearance, function and reliability. Introducing correct lubrication in the machining zone could improve the tribological characteristic of Al6061-T6 leading to higher product quality. In this research work, the optimum SiO₂ nanolubrication parameters in milling of Al6061-T6 are investigated to achieve correct lubrication conditions for the lowest cutting force, cutting temperature and surface roughness. These parameters include nanolubricant concentration, nozzle angle and air carrier pressure. Taguchi optimization method is used with standard orthogonal array L₁₆(4)³. Furthermore, analyses on surface roughness and cutting force are conducted using signal-to-noise (S/N) response analysis and the analysis of variance (Pareto ANOVA) to determine which process parameters are statistically significant. Finally, confirmation tests were carried out to investigate the optimization improvements.