喷油嘴喷孔流道磨料流光整特性仿真与试验

喷油嘴喷孔流道入口有一定入口倒角和喷孔锥度,能通过提高喷油嘴的燃油雾化效果来进一步提高发动机的效率。通过软性流体磨料对喷孔流道进行加工,使喷孔流道入口有一定的入口倒角和喷孔锥度。结果表明：在5 MPa、8 MPa的入口压力下,使用平均粒径为5μm、质量分数为25%的软性磨料加工800 s后,测得喷孔入口倒角曲率半径分别为0.018 mm和0.010 mm,喷孔流道锥度为1°和3°。在不同的入口压力下,通过polyflow软件对软性流体磨料在喷孔流道的流动特性进行了分析,并通过试验进行验证,发现仿真与试验结果误差在允许的范围内,证明了数值分析的可靠性。     

钛合金磨料流光整加工表面完整性研究

目的 研究磨料流光整加工钛合金格栅表面完整性。方法 用电火花加工制备钛合金试样,通过磨料粒径、加工压力、加工次数的单因素试验,来研究其对试样表面粗糙度和表面形貌的影响规律,选用三种初始粗糙度不同的钛合金试样来进行磨料流光整加工效果试验,对比分析磨料流光整加工对试样表面残余应力的影响,进行加工次数的单因素试验研究磨料流加工过程中其对工件表面显微硬度的影响。结果 对于钛合金试样来说,磨料粒径和加工压力越大,表面抛光效果越明显,表面粗糙度就越低。当磨料粒径从38 μm增加到420 μm时,相对应的表面粗糙度值Ra从5.815 μm降低到0.824 μm;当加工压力从8 MPa增加到24 MPa时,相对应的表面粗糙度值Ra从4.314 μm降低到1.398 μm。而随着加工次数的增加,表面粗糙度值Ra从整体上呈现下降趋势,最后趋于稳定,当加工次数从10增加到80时,相对应的表面粗糙度值Ra从5.925 μm降低到0.307 μm,并且最后稳定在0.300 μm附近。钛合金试样经磨料流光整加工之后,表面残余应力由原来的拉应力变成了压应力。随着加工次数的增加,钛合金试样表面显微硬度整体上呈现先减小后增大的趋势,当加工次数从10增加到50时,显微硬度值从532.83HV降到357.73HV,当加工次数从50增加到90时,显微硬度值从357.73HV上升到393.48HV,试样表面显微硬度的均匀性也显著增加。结论 增大磨料粒径和加工压力或者增加加工次数,都能降低工件表面粗糙度,钛合金工件经过磨料流光整加工之后,表面完整性有较大改善。     

基于有限元方法的磨料流加工数值模拟

利用Fluent软件对磨料流加工过程中流体磨料的流动形态进行了数值模拟分析,得到了流体磨料在圆孔类工件内沿孔道壁面的压力分布和沿径向的速度分布;并通过改变流体磨料的加工压力,得到工件进出口压力差与工件内流体磨料流速的变化规律.又通过模拟结果与实验结果对比,表明应用Fluent软件预测工件进出口压力差模拟计算的可行性,为...     

基于磨料流加工技术叶片泵转子去毛刺试验研究

针对叶片泵转子叶片槽两侧面及槽底孔内毛刺不能被彻底去除的问题,提出基于磨料流加工技术的方法,建立磨料流体三维模型,利用Fluent软件模拟分析槽底孔中心及槽道边沿压力分布,设计装夹方案并进行现场试验。加工后的槽道内壁光滑,无毛刺,表面粗糙度值未显著变化,尺寸精度未受影响,表明磨料流加工技术可有效去除转子槽内的毛刺。     

涡轮叶片电解加工阴极设计方法研究

电解加工技术是目前航天航空发动机核心零部件涡轮叶片的主要加工方法之一.叶片电解加工工具阴极设计方法与修正是提高叶片电解加工精度的关键.电解加工中阴极进给角度、工件装夹角度和工件型面法线方向夹角的规范性和均匀性是影响阴极设计准确性的重要因素.分析某小型发动机涡轮转子叶片三维模型结构,建立叶片型面上各采样点对应的阴极工具型...     

磨料流加工中夹具设计的研究

磨料流加工(AFM)是光整加工领域的一项新技术。磨料流加工由磨料流加工机床,夹具和流体磨料三部分组成。当用磨料流加工形状较复杂的零件时,夹具设计的好坏对表面加工质量和加工效率有重要的影响。本文分析了磨料通过工件孔道的特性。介绍了用于研究材料去除量与加工距离和形状关系的实验。材料去除量在通道两端比中间小是磨料流加工的一基本特性。本文讨论了如何避免因此而产生的工件变形以及如何利用这一特性来获取某种特殊效果。最后,给出了一个用于加工某不锈钢三通体的夹具。     

涡轮叶片造型方法的研究

对涡轮片进行精确的数学描述是对其进行数控加工的前提，本文讨论了在给定叶片沿叶高方向上截面数据的情况下，采用双三次B样条拟合法和三次NURBS曲面插值法构造叶片曲面的具体算法，分析了两种方法的优缺点，并给出了具体的算法和公式，深入探讨了叶片构造过程中遇到的部分网格确定，插值曲面构造，圆弧的二次NURBS曲线精确表示，NURBS曲线节点插入算法及其升降阶等关键性技术问题。     

连杆大头孔磨料流加工的理论探讨及实验研究

针对H12V190Z柴油机连杆大头孔表面的磨料流加工方法进行了研究,利用CFD软件对其加工流场进行了模拟仿真,得到了流体磨料在流场中的压力和速度分布。结合工艺实验验证了经磨料流加工后连杆大头孔加工表面的粗糙度值有明显的减小,提高了连杆表面的质量,大大缩短了加工时间,提高了加工效率。     

精密零件的微磨料气射流光整加工

近年来,在非传统去毛刺加工方法中,微磨料气射流去毛刺由于初始成本低、生产效率高、灵活性强、无应力、无热影响区,在精密零件的光整加工中获得了广泛的应用。本文详细介绍了微磨料气射流用于光整加工去毛刺的加工原理、材料去除机理、去毛刺的工艺参数以及对棱边尺寸的影响,并列举了一些微磨料气射流在不同应用领域的加工实例。     

A study of internal face finishing of the cooling channel in injection mold with free abrasive grains

This paper deals with a finishing method for the internal face of a cooling channel located in an injection mold that makes use of free abrasive grains. The injection mold is fabricated by layered manufacturing equipment using a ferrous based metal powder. When the internal pressure is loaded to the hydraulic cylinder, the solution containing the free abrasive grains is passed through the cooling channel. The internal face is then finished by the free abrasive grains. The effects of various conditions on finishing characteristics are investigated experimentally. The results showed that the internal face roughness of the cooling channel improved significantly during the first 1000s of finishing. The significant improvement achieved during the initial stages of finishing is due to the removal of the aforementioned unstable powders. Free abrasive grains are employed to remove the unstable powder on the internal face rather than to polish the alloyed face. The high-speed flow of the free abrasive grains results in an increase in their kinetic energy, thereby increasing the force with which they collide with the internal face and resulting in an improvement of the surface roughness. The internal face finishing was effective for the improvement of the thermophysical properties in the cooling channel.     

Machining of turbulated cooling channel holes in turbine blades

Whilst the introduction of turbulators in cooling channels improves the cooling efficiency, it makes the machining of the channels with a shaped tube electrolytic machining (STEM) drill in a single pass difficult. This paper describes an algorithm to model the machining of a given turbulator shape by changing the feed rate at regular intervals. This algorithm is iterative and relies on predicting the workpiece shape using the boundary element method (BEM) at each stage of the analysis. The algorithm is verified by comparing the predicted and machined shapes of a turbulator; it is shown that the resulting accuracy is good.     

Simulation of fabrication for gas turbine blade turbulated cooling hole in ECM based on FEM

Electrochemical machining (ECM) is an important manufacture technology in machining difficult-to-cut materials without tool wear and residual stress. In this study, ECM is used to machine the turbulated cooling hole on gas turbine blade for enhance efficiency of aircraft engine. However, because of the eroded size is hard to be determined in ECM, a new approach by employing computer simulation method is applied to overcome this difficulties. Mathematical model based on the various parameters is developed. Finite element method (FEM) is selected to analyze the electric field distribution and compute the corrosion process of the material by using the time-dependent simulation method. Minimum deviation of the simulated anode profile shape from the experimentation is performed. Furthermore, this proposed method could reduce the number of trials and save the expense greatly.     

Investigation of the finishing characteristics in an internal tube finishing process by magnetic abrasive finishing combined with electrolysis

In this research, the finishing characteristics in a tube's internal finishing process using the method of magnetic abrasive finishing (MAF) combined with electrolysis has been studied. Electrolysis produces an aluminium oxide film that accelerates the removal of the initial hairline morphology on the surface. Subsequently, the film is removed with MAF. This process significantly minimises the surface roughness in a reduced time. The way the finishing conditions, such as the pole–pipe gap, iron particle size and abrasiveness combinations, and processing time affected the surface morphology in the MAF machining process has been particularly examined. The surface roughness was measured and images of the finished surfaces were recorded to study the morphology changes. Prolonged electrolysis finishing was seen to deepen the oxidation film and pits, which adversely affects the surface. This evidence suggests that the pit residuals contribute to higher surface roughness values.     

Directional solidification casting technology of heavy-duty gas turbine blade with liquid metal cooling (LMC) process

In this work, some important factors such as ceramic shell strength, heat preservation temperature, standing time and withdrawal rate, which influence the formability of directionally solidified large-size blades of heavy-duty gas turbine with the liquid metal cooling(LMC) process, were studied through the method of microstructure analysis combining. The results show that the ceramic shell with medium strength(the high temperature flexural strength is 8 MPa, the flexural strength after thermal shock resistance is 12 MPa and the residual flexural strength is 20 MPa) can prevent the rupture and runout of the blade. The appropriate temperature(1,520 ℃ for upper region and 1,500 ℃ for lower region) of the heating furnace can eliminate the wide-angle grain boundary, the deviation of grain and the run-out caused by the shell crack. The holding time after pouring(3-5 min) can promote the growth of competitive grains and avoid a great deviation of columnar grains along the crystal orientation 001, resulting in a straight and uniform grain structure. In addition, to avoid the formation of wrinkles and to ensure a smooth blade surface, the withdrawal rate should be no greater than the growth rate of grain. It is also found that the dendritic space of the blade decreases with the rise of solidification rate, and increases with the enlarging distance between the solidification position and the chill plate.     

汽轮机叶片无余块锻造

针对汽轮机叶片锻造余块给后续加工带来困难,分析了汽轮机叶片锻件上的余块结构特点,提出了无余块锻造工艺.采用一个过渡面,实现叶根(或叶冠)分型面与叶型分型面过渡,取缔了原有的锻造余块过渡,经实践证明是可行的.这一新工艺节省材料,提高生产效率,降低了生产成本,促进汽轮机叶片锻造技术进步,对于其他具有余块锻件的工艺改进有参考价值.     

汽轮机叶片司太立合金高频钎焊工艺

汽轮机动叶片 (以下称叶片 )的工作条件恶劣 ,对材料的要求苛刻 ,叶片的水蚀防护要求较高。为了降低制造成本 ,某电厂机组末级叶片采用在1Ｃｒ12Ｎｉ3Ｍｏ1ＶＮ (Ｓ/ＳＪ2 )材料上高频钎焊司太立合金片的方法 ,替代 17- 4ＰＨ材质的叶片 ,既达到了防水蚀的要求又降低了制造成本。1　试件制备在 1Ｃｒ12Ｎｉ3Ｍｏ1ＶＮ长 4 30ｍｍ、宽 12 0ｍｍ、厚15ｍｍ的两块试板的一侧 ,加工出 2 6 0ｍｍ× 12ｍｍ凹槽。凹槽底部厚 2ｍｍ ,完全模拟正式生产中的叶片钎焊合金片凹槽尺寸。2　焊前准备　(1)按技术条件检查叶片及凹槽加工尺寸和质量 ,并进行…     

大型风能发电机组叶片再设计系统研究

叶片的外形设计和翼型的选择是影响风力机性能和产能效率最为核心的技术。提出了一种大型风能发电机组叶片再设计的原理和方法,对叶片模型进行剖析,寻找几何特征,探索制约叶片形状的基本因素,确定叶片截面参数计算公式,利用所开发的叶片翼型自动生成系统,完成了叶片的再设计,并得到了实际应用。结果表明：这种再设计方法满足产品设计需求。     

汽轮机叶片锻模失效分析

对汽轮机叶片锻模的结构特点进行了分析,并对失效后的锻模进行了蓝光扫描试验、宏观观察断口、扫描电镜、能谱分析、硬度检测等分析与研究,找出锻模失效的主要形式和根本原因,针对汽轮机叶片锻模的使用情况,提出了延长锻模使用寿命的方法。     

汽轮机叶片锻坯优化设计

分析了汽轮机叶片锻坯设计所存在的问题:锻件飞边不均匀、试锻次数多等缺点;介绍了汽轮机叶片锻坯优化设计方法、步骤及其关键技术;借助于有限元正向模拟的方法,通过对叶片模锻成形模拟分析,得到了较为合理的叶片锻坯形状与尺寸.以RL1016叶片锻坯设计为例,进一步阐述了采用合理的经验参数初步设计汽轮机叶片锻坯,应用有限元数值模拟进行检验,经生产实践证明是可行的.这种设计方法提高了材料利用率,减少了试验次数,甚至可取消试锻,对于形状类似锻件的工艺设计有参考价值.