整体叶轮叶片型面的精密展成电解加工

介绍采用四轴联动方式精密展成电解加工整体叶轮叶片型面的实现方法,并针对某航空发动机上的一整体叶轮进行了叶片型面的精加工试验,取得了良好的试验结果。     

整体叶盘型面电解加工阴极进给方向优化及试验研究

电解加工技术是航空发动机整体叶盘零件主流加工技术之一。电解加工中阴极进给方向与阳极型面法线方向夹角的均匀性是影响加工精度的重要因素。为进一步提升整体叶盘型面电解加工精度,针对工具阴极进给方向优化设计问题开展研究。通过研究阴极进给方向与阳极型面法线方向夹角变化对电解加工极间间隙的影响,在分析传统进给方向存在的不足基础上,提出一种叶盘电解加工阴极进给方向优化方法。该方法以阴极进给方向与叶片型面法线方向夹角集合中的最大夹角值为评判指标,以评判指标值最小为判优准则。为验证优化方法的有效性,开展整体叶盘电解加工中阴极进给方向优化设计,采用黄金分割法获得了优化进给方向的最优解。与传统进给方向相比,优化后的进给方向显著提升了夹角分布的均匀性。开展传统进给方向与优化进给方向的加工比较试验以及多叶片扇段加工试验,试验结果表明采用优化进给方向可显著提高加工精度。     

精密展成电解加工整体叶轮的展成运动轨迹确定

介绍了以四轴联动方式精密展成电解加工直纹面叶型整体叶轮叶片型面时，叶片型面的拟合方法、展成运动的组成以及展成运动轨迹的计算方法。结合实际加工工艺，考虑加工间隙变化情况、工具阴极加工刃边宽度影响以及叶片表面形状影响等因素，对展成运动轨迹的修正算法进行了研究，并对某小型整体叶轮叶片型面进行了加工试验。加工后的叶片型面，其各给定截面内的叶片型线误差小于0．1mm，表面粗糙度Rn小于0．8μm。     

复合进给电解加工机床的研制

针对现有电解预加工叶片型面复杂、叶栅通道扭曲的整体叶盘时存在的加工余量分布不均、余量差过大等问题,分析了现有技术中工具电极单一直线进给的缺点,基于工具电极可直线与旋转复合进给加工方法,研制了可以实现复合进给运动的电解加工机床,并配合基于PMAC的开放式数控系统,使该机床具有高精度、高柔性、开放化等特点,同时,研究了机床最优进给路径的实现方法,从理论上证明了该方法的优点及可行性。相较于现有技术,该机床有助于提高叶栅通道的加工精度、减小加工余量差,为后续叶片型面精加工奠定了良好的加工基础。     

整体叶轮数控展成电解加工运动轨迹及速度研究

在整体叶轮扭曲叶片型面加工方法中,数控展成电解加工展示了其优势。本文针对某型号航空发动机整体叶轮的加工,首先阐述了利用直纹面拟合扭曲型面的方法,然后通过对四轴数控展成电解加工过程的分析,采用不共原点的坐标变换对加工中的工件运动进行了研究,获得了各轴运动轨迹及工件上任意点的速度,分析了速度对展成电解加工间隙的影响,提出了编制数控加工程序的方法。最后,用试验对利用此法编制的数控加工程序进行了验证,试验结果表明该法能加工出符合要求的叶片型面。     

数控展成电解磨削整体叶轮叶片型面的研究

为解决整体叶轮叶片型面的精加工难题 ,进行了五轴联动数控展成电解磨削的基础研究。根据数控展成电解磨削整体叶轮叶片型面这一加工方法的特点 ,在分析了数控展成电解磨床的结构与运动的基础上 ,介绍了经济型多轴数控系统及其联动控制方法 ,建立了电解磨削非平行直纹展成曲面的数学模型 ,开发了五轴联动数控展成电解磨削自动数控编程系统 ,对航空发动机整体叶轮的叶片型面进行了电解磨削的工艺试验。结果表明 ,数控展成电解磨削工艺的加工精度和表面粗糙度可满足整体叶轮的技术要求。     

整体叶盘叶栅通道电解加工流场仿真研究

电解加工是航空发动机整体叶盘制造的主要技术之一,加工间隙内电解液流动的均匀性是影响加工稳定性和表面粗糙度的核心因素。针对叶栅通道电解加工,对比分析电解液侧流式下的正向流动与反向流动加工间隙内流场状态,通过数值仿真对比分析可知,正流方式下加工间隙内电解液流速较高,流场均匀性较好,故正流方式有利于叶栅通道电解加工。开展了电解液正流电解加工试验,结果表明,采用正流方式进行叶栅通道电解加工,轮毂粗糙度可达0.316μm,叶盆、叶背余量重复误差分别为0.096 mm,0.103 mm,为下一步叶片型面精加工提供了良好的条件。     

双叶片套型电解加工流场设计及优化

具有大小双叶片的扩压器能够改善压气机的性能,在航空发动机中得到广泛应用。此类构件多采用高温合金等难切削材料制造,传统铣削加工存在刀具损耗等问题。电解加工技术具有无机械切削力、工具阴极无损耗等特点。提出一种双叶片套型电解加工的方法,基于法向流程等距的原则设计了叶间出液通道,建立了出液通道宽度递增的流道模型,开展了流场仿真研究,当出液通道的宽度为0.9 mm时,加工区域内电解液的流速分布最均匀。选择GH4169材料进行了双叶片套型电解加工的对比试验,试验结果表明,采用叶间出液的电解液流动方式,加工稳定性得到提高,阴极进给速度由0.6 mm/min提高至1.0 mm/min,材料去除速率达到1 396.5 mm³/min,叶片锥度降低至1：14.29以下,轮毂表面形貌得到改善。     

基于叶栅通道可加工性分析的整体叶盘径向电解加工阴极设计及实验

为提高叶栅通道加工质量,针对径向进给的电解加工方式,分析了通道可加工性问题,通过通道模型离散化处理,得到了加工边界曲面;讨论了进给角度与加工余量均匀性的影响,确定了合理的进给方向。在此基础上对阴极侧面轮廓和端面型面进行了设计,并制备了加工所需的工具阴极,利用自行研制的整体叶盘电解加工平台开展了工艺实验。结果表明:加工出的通道试件轮毂成形精度高,叶根部位加工质量好,叶盆、叶背余量分布均匀一致,能够满足后续叶片精加工要求。     

五轴数控电解开槽加工整体涡轮盘的工艺试验研究

为解决整体涡轮盘机械加工效率低的问题,提出利用简单锥形回转体工具对某型号整体叶轮进行五轴数控电解开槽加工。首先分析了五轴数控电解加工的基本原理,建立加工模型,通过模拟加工电场分布,预测加工过程可能出现问题。再根据叶片几何形状和电解液流场优化分析结果,设计合理的数控电解加工用阴极工具,通过试验分析电压、阴极工具转速、电解液压力、温度等主要因素对加工结果的影响规律。最后基于自动数控编程软件编译合理的数控代码,采用优化的参数组合成功加工出多个整体涡轮盘叶片。满足了实际生产要求。     

Machining the Integral Impeller and Blisk of Aero-Engines: A Review of Surface Finishing and Strengthening Technologies

The integral impeller and blisk of an aero-engine are high performance parts with complex structure and made of difficult-to-cut materials. The blade surfaces of the integral impeller and blisk are functional surfaces for power transmission, and their surface integrity has significant effects on the aerodynamic efficiency and service life of an aero-engine. Thus, it is indispensable to finish and strengthen the blades before use. This paper presents a comprehensive literature review of studies on finishing and strengthening technologies for the impeller and blisk of aero-engines. The review includes independent and integrated finishing and strengthening technologies and discusses advanced rotational abrasive flow machining with back-pressure used for finishing the integral impeller and blisk. A brief assessment of future research problems and directions is also presented.     

航空发动机整体叶盘刀具性能灰色综合评价

以某型航空发动机钛合金整体叶盘的数控铣削为研究对象,提出了一种面向航空发动机整体叶盘的数控铣削刀具性能灰色综合评价方法。首先设计涵盖航空发动机整体叶盘难加工特征的基准件模型,然后基于灰色关联度分别构建了粗精加工刀具性能灰色综合评价模型,最后进行基准件的切削试验并应用所建立的灰色综合评价模型对刀具性能进行综合评价。研究结果表明,所构建的基准件模型和灰色综合评价模型可以快捷、有效地评价刀具性能。     

先进焊接技术在发动机整体叶盘修复中的应用

整体叶盘是现代航空发动机的一种新型结构部件,对于提高发动机性能具有重要作用。当整体叶盘在加工过程中出现缺陷或在使用过程中发生损伤,如果无法进行修复,将导致整个叶盘报废,并造成巨大的经济损失。可见,整体叶盘的修复技术是整体叶盘应用和发展的瓶颈。本文研究了整体叶盘损伤失效的特征,分析了激光熔焊、钨极氩弧焊、激光熔覆、激光成形修复及线性摩擦焊等5种修复技术的工艺特点及应用情况,就整体叶盘修复技术的发展提出了建议。     

整体叶盘数控铣削优化技术探讨

针对整体叶盘数控铣削过程中存在的难题,从最优化的角度出发,结合近年来国内外文献研究,从铣削工艺方案优化和工艺参数优化两方面进行介绍,重点对刀具可达性、加工效率、颤振变形、刀具磨损以及优化模型、优化算法等相关优化技术的研究现状进行综述。通过分析现有研究中存在的一些难题,探讨了整体叶盘数控铣削优化技术的研究方法,对后期开展整体叶盘制造技术研究具有一定的参考意义。     

由涂层引入失谐的整体叶盘集中参数建模与振动特性分析

为了研究涂层参数失谐对整体叶盘振动特性的影响,创建含涂层的两自由度扇区集中参数模型,引入四种常见的主动失谐形式,详细分析了涂层质量、刚度、阻尼等参数失谐对系统振动特性的影响规律。创建含涂层参数失谐的整体叶盘集中参数模型,并由涂层引入常用的谐波、交替、线性及伪谐波四种形式的主动失谐。建立失谐后整体叶盘结构的运动方程,确定求解其固有频率及振动响应的方法,并给出了评价失谐程度的量化参数。通过实例分析了由涂层引入主动失谐后叶盘结构的振动特性。研究表明,叶盘系统发生由涂层引起的主动失谐后,系统最大响应随失谐量的增大呈现先上升后下降的趋势,有“阈值”现象。     

Research on tool path planning method of four-axis high-efficiency slot plunge milling for open blisk

The great mass of machining allowance for blisk is removed in the rough milling, so improving the rough machining efficiency for the blisk’s tunnel is the key of realizing high-efficiency machining of blisk. According to the structure characteristic of open blisk’s tunnel, a four-axis plunge slot rough milling with high-efficiency and low machining cost is advanced. First, the plunge slot process for blisk and the generation process of the ruled enveloping surface for the freeform surface of the blisk’s blade are put forward. Then, the generating method of the ruled enveloping surface for the blade’s freeform surface and the tool path generation method of four-axis plunge slot milling for blisk are studied. The rough milling region of open blisk’s tunnel is determined by generating the ruled enveloping surface of blade’s offset surface, and the algorithm of tool path for four-axis plunge milling is given. When using a ruled surface to approach a freeform surface, the problem of getting boundary is solved, and the error from the calculation of tool path is avoided by the algorithm. At last, the experiment shows that comparing to the traditional side slot milling, the cutting force of four-axis plunge milling can be reduced by 60% and even the rough machining efficiency can be increased to more than double.     

Electrical discharge machining of electron beam melting formed shrouded blisk

Shrouded blisk components are one of the core parts in aerospace engines. Five-axis or six-axis electrical discharge machining is once regarded as the best solution to manufacturing these components. The machining process, however, is time consuming and money cost. In this paper, an electron beam melting (EBM) and electrical discharge machining (EDM) combined method for shrouded blisks manufacturing was presented. In the new method, EBM was used to generate the near-net forming blank of the shroud blisk, and EDM was responsible for finish machining. The mechanical properties of the EBM formed Ti6Al4V blank was tested to be good enough for shrouded blisks. A visual identification method was proposed to establish the machining reference on the EBM formed blisk blank for the subsequent EDM process. The given example showed the required blade accuracy of ±0.03 mm can be achieved by the visual identification method. Through the combination of EBM and EDM method, the machining time of the shrouded blisk was greatly reduced by 54.8 %.     

The tool design and experiments on electrochemical machining of a blisk using multiple tube electrodes

The International Journal of Advanced Manufacturing Technology - Electrochemical machining (ECM) is an effective method for machining a blisk. Because a blisk often has several tens to hundreds of...     

基于UG二次开发的叶轮刀位轨迹生成

整体叶轮型面的复杂性,导致造型和数控编程都有一定的难度.基于UG基础开发平台,根据全局干涉刀位修正原理,编制了无干涉刀位轨迹算法,开发出干涉较严重的微型叶轮类零件的5坐标加工程序.通过实验证明,无干涉刀位轨迹算法是可行的,且基于UG平台开发的算法计算速度快,操作方便,精度易于控制.     

Flow field design and experimental investigation of electrochemical machining on blisk cascade passage

Electrochemical machining (ECM) provides an economical and effective way for machining heat-resistant, high-strength materials into complex shapes that are difficult to machine using conventional methods. It has been applied in several industries, especially aerospace, to manufacture blisk. The electrolyte flow field is a critical factor in ECM process stability and precision. To improve the process stability and the efficiency of blisk cascade passages, ECM with a radial feeding electrode, a rational electrolyte flow mode for electrochemical machining called “Π shape flow mode”, is discussed in the paper. Three flow field models are described separately in this report: traditional lateral flow mode, positive flow mode and Π-shaped flow mode, and the electrolyte velocity and pressure distribution vectors for each flow mode are calculated by means of a finite element fluid analysis method. The simulation results show that the electrolyte flow is more uniform with the Π-shaped flow mode. The deformation of the cathode, which is caused by the pressure difference, is also analysed in this report. The cascade passage ECM with a radial feeding electrode was experimentally tested out to evaluate the rationality of the flow field, and the fluctuation of current during the process was less than 1 %, which means that the process that uses the Π-shaped flow mode is stable. The feeding velocity of the cathode with the Π-shaped flow mode is approximately 70 % higher than that with the other two flow modes, and the incidences of short circuiting are obviously decreased. The surface roughness of the blisk hub is only 0.15 μm, and the machining error of the hub is less than 0.1 mm. The results demonstrate that using the Π-shaped flow mode can enhance the quality, stability and efficiency of blisk cascade passage ECM.