典型精锻模设计实例——第四讲 航空发动机风扇叶片等温锻模

航空发动机风扇叶片等温锻模,叶片的锻件见图1。 一、工艺分析 叶片的材料为TC4（Ti-6Al-4V）,投影面积为9000mm^2。采用常规的锻造方法,叶片各面都留有机械加工余量,需花大量的铣磨工时。为了节约昂贵的钛合金材料并减少难于机械加工的工时,采用等温精密模锻的方法。高精度的叶片不仅要求模具材料耐磨而且要求机加工精度非常高。对钛合金的等温模锻和常规模缎的工艺参数的比较列于表1。     

钛合金复杂件等温锻造研究

针对TC4钛合金非对称变截面复杂件在加工过程中锻造温度范围窄、充型能力差、容易产生皱褶等问题,研究了TC4钛合金等温锻造的工艺过程,并采用DEFORM 3D有限元软件进行了数值模拟。结果表明:采用等温锻造工艺,成功的锻造出了某钛合金复杂件,且该锻件轮廓清晰,表面光洁,尺寸精度高;该锻件金属流线分布合理,组织性能超过了常规锻件;该锻件材料用量相对普通锻件材料用量可减少60%。通过软件模拟,了解锻件成形的应力应变及行程载荷等情况。     

钛合金弹翼接头等温锻造工艺研究

针对钛合金弹翼接头加工中的问题,借鉴以往钛合金等温锻造工艺,提出了钛合金TC4弹翼接头等温锻造的新工艺．探讨了钛合佥弹翼接头等温锻造的工艺参数、模具结构、锻坯形状尺寸及润滑剂的选择,并讨论了其模具材料及加热方式的选择。     

TC11钛合金压气机盘等温锻造工艺研究

钛合金的比强度高、耐热和耐蚀性能良好,但比较昂贵,机加工也较困难。采用常规锻造,组织不均匀,产生的变形抗力极大,而且钛合金的锻造温度范围窄,变形抗力受变形速率、变形温度的影响极大。采用该工艺生产钛合金压气机盘需要较大能量的设备,如10t模锻锤、63t·m对击锤,而且     

有限体积法研究钛合金叶轮等温精密成形

针对钛合金叶轮形状复杂、受力状况恶劣以及钛合金材料导热率低的特点,研究了叶轮等温锻造工艺中叶片顶部形状的设计、坯料直径的选择以及工艺参数的制订等技术难点.采用有限体积法模拟了Ti-6A1-4V钛合金叶轮的等温精密成形过程,分析了成形过程中金属的流动行为和对模具的充填能力,给出了成形各阶段工件的温度场和应变速率场分布情况.模拟结果表明,等温精密锻造钛合金叶轮,不仅可以获得很好的金属流线和满意的几何形状,而且由于成形的温度和应变速率条件有利于Ti-6A1-4V材料发生超塑性变形,还可以得到分布均匀的等轴细晶组织,提高锻件的力学性能.     

钛合金等温锻造中润滑的应用研究

针对钛合金等温锻造过程中润滑的关键性,在借鉴以往钛合金等温锻造工艺的基础上,探讨了钛合金等温锻造工艺过程中的润滑荆的选择及玻璃润滑剂润滑工艺和去除方法。     

2A70铝合金转子等温闭塞式锻造工艺研究

2A70铝合金转子是导弹发动机上重要的受力构件,对组织性能的要求很高。采用等温闭塞式锻造的方法生产转子锻件。为了使成形后的锻件顺利出模,采用了组合式凹模的结构。等温成形时,进行了大量的试验研究加热温度对成形过程的影响,最终确定模具和坯料的加热温度均为435 ℃。经检测,采用所设计的工艺方案生产的转子锻件的尺寸精度及组织性能均符合设计要求,成功地解决了切削加工的转子力学性能差、不能满足使用要求的问题。     

2A14铝合金等温模锻成型技术

采用2A14铝合金等温模锻成型轮毂,研究模具设计、材料规格、锻造温度和热处理等工艺参数对合金力学性能及组织的影响,并与普通锻造的力学性能及组织进行了对比。2A14铝合金等温锻造态下的组织比普通锻造的组织明显细化,力学性能得到了显著提高;此外,采用该工艺锻造出的轮毂,具有尺寸精度高、工艺稳定、成型快速、材料利用率高和生产效率高等优点,具有极高的工程价值和发展前景。     

TC4钛合金等温锻造工艺数值模拟

采用DEFORM 3D有限元分析软件数值模拟TC4钛合金等温锻造过程.通过软件模拟,了解锻件成形的应力应变及金属流动等情况,为工艺的确定和设备的选取提供理论依据.     

等温锻造对TC6钛合金组织和性能的影响

为确定（α＋β）两相区内等温锻造工艺参数对TC6钛合金组织和性能的影响,分别在不同温度和速度条件下对TC6钛合金进行了等温锻造。研究结果表明,在所选择的参数范围内,得到的组织均为双态组织;组织性能对锻造温度较为敏感;锻造速度和温度对TC6钛合金室温力学性能影响较小。     

国内外镁合金等温锻造进展

镁合金常温下塑性差、散热快,在共晶温度以上锻造时会发生严重开裂,这就决定了镁合金不宜采用常规锻造方法。等温锻造成形过程中温度基本不变,可消除镁合金在常温下成形性能差的问题。介绍了国内外镁合金等温锻造的发展及其成形温度和变形程度等工艺。     

一种新型近α钛合金锻造工艺的优化

通过对一种新型Ti-Al-Zr-Mo系近α钛合金进行不同的锻造工艺,来获得不同的显微组织,并研究这些不同的显微组织对合金力学性能的影响规律,最终得出与力学性能合理匹配的最优化锻造工艺。研究表明：经过β相区均匀化处理,在920℃下锻造后合金的组织及性能达到最佳匹配。     

Preform design for large-scale bulkhead of TA15 titanium alloy based on local loading features

Large-scale TA15 (Ti–6Al–2Zr–1Mo–1V) titanium alloy bulkhead is a key lightweight load-bearing structure part in an aircraft, which has a large plane view and has a complex shape with high ribs and thin webs. In its forging process, the forming defects, such as folding and under-filling are prone to occurrence. The near-net shape forming with saving force of this large-scale complex component can be realized with proper preform design combining local loading condition. By analyzing isothermal local loading process characteristic of large-scale bulkhead, it indicates that the simple unequal-thickness billet is suitable for small lot manufacture of large-scale TA15 titanium alloy bulkhead. Considering the geometry and forming characteristics, such as large dimension, complex shape, mass data, etc., a design method of unequal-thickness billet using analytical analysis and numerical simulation is proposed. The preform for a large-scale TA15 titanium alloy bulkhead is designed by the proposed method. The basic three-dimensional shape of billet is determined by the analytical models based on local loading features, and the basic billet is modified according to numerical simulation result and considering the local loading forming characteristic, and then the preform without resulting in folding and under-filling can be obtained after two modifications.     

Precision forging technology for aluminum alloy

Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.     

BT25钛合金动态再结晶行为的元胞自动机模拟

为研究热加工工艺参数对钛合金塑性成形过程中微观组织的影响,利用Gleeble-3500型热模拟试验机对BT25钛合金进行单道次等温恒应变压缩试验。分析真应力-应变曲线,建立JMAK动态再结晶动力学方程;通过对热变形行为的分析,推导出钛合金的位错密度模型、再结晶形核和晶粒长大模型;结合元胞自动机的算法,建立元胞自动机(Cellular automata, CA)模型并利用该模型模拟和验证了BT25钛合金热变形过程中动态再结晶行为。结果表明,BT25钛合金的流动应力对应变速率和变形温度非常敏感;提高变形温度或降低应变速率均有利于材料发生动态再结晶;CA模型模拟晶粒尺寸误差约为3%,预测DRX体积分数误差在10%以内。该模型具有良好的预测精度,为合金材料在塑性加工过程中优化工艺参数和控制锻件微观组织演变提供了可靠性依据。