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《计算机集成制造系统》2015,(2)
针对压气机辊轧叶片前后缘头后续数控加工制造与叶身圆滑转接的要求,提出一种基于夹持态叶片缘头多测绘点的一次配准和制造公差约束的二次配准的辊轧叶片前后缘圆滑转接建模方法,该方法可以更精确地构建辊轧叶片前后缘头圆滑转接计算机辅助设计模型,满足后续数控加工的需求。进行基于实测数据的建模验证,结果表明所提方法可以实现辊轧叶片无余量叶身与缘头区域的高精度圆滑转接。 相似文献
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《机械工程学报》2017,(16)
航空发动机高压压气机叶片在辊轧成形过程中会沿着弦长方向发生回弹,直接影响叶片的成形精度进而影响其气动性能。为实现航空发动机压气机叶片无余量辊轧成形,提出并研究基于截面线回弹补偿的叶片辊轧模腔优化设计方法。分析钣金件弯曲变形过程并基于钣金件的几何结构和材料特性建立回弹前后中心角的变化模型。在此基础上提出叶片截面回弹补偿模型,并对辊轧叶片工艺模型截面进行回弹误差补偿。将回弹补偿后的叶片工艺模型截面线族绕轧辊轴线进行扇态分布并重构辊轧模具型腔。基于数值计算方法使用几何映射和回弹补偿设计的型腔对叶片辊轧成形过程进行模拟,并获得了相应的轧制成形叶片模型。结果表明,回弹补偿后的模具型腔能够有效提高叶片型面的成形精度,叶片成形误差缩小到原来的16.7%。本文研究内容为压气机无余量辊轧成形模具设计提供理论支撑,同时对不规则薄壁类结构塑性成形精度控制具有参考价值。 相似文献
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航空发动机叶片修复往往先采用激光熔覆,然后精密铣削。叶片变形和破损可能造成熔覆材料不足或铣削结果超差。为了给叶身熔覆和铣削提供足够的余量和满足设计要求的目标加工曲面,提出镜像模型驱动的叶身自适应修复曲面重构方法。以叶身设计曲面作为理论模型,以实际待修复叶身的测量值作为实作模型,引入叶身形状公差约束和叶身变形对熔覆和铣削加工的约束,建立了保证叶身曲面设计要求的目标曲面优化模型,并基于镜像模型优化处理熔覆阶段与铣削阶段的目标曲面。通过实例验证了所提优化模型的有效性和必要性。 相似文献
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基于轧件成型过程中的实际几何形状,通过分析成型过程中轧件变形区的变形特点,选取一个特定的平面建立坐标系,求得了轧件变形区各曲面的直角坐标系方程,与参数方程相比形式简洁,计算简单,简化了曲面面积、轧件体积以及轧齐曲线设计的计算。 相似文献
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为了缩短离心叶轮叶片的三维设计周期,实现闭式离心叶轮自由曲面叶片的三维快速成型,本文提出了一种基于叶片中间面的自由曲面叶片快速成型方法。首先,采用三次均匀B样条理论对叶片中间面曲线坐标进行双向加密重构;然后,结合空间曲线参数方程及空间矢量相加法,则以重构后的中间网格面为基准建立初始叶片三维网格模型;最后,采用叶片中间面曲线坐标点绕轴旋转形成的空间曲线和初始叶片三维微元网格求交,求解获得单个自由曲面叶片曲面离散坐标。整个叶片三维建模过程可实现不同前、尾缘及厚度形状组合的离心叶轮三维叶片快速成型;该方法和传统的CAD建模方法相比,其调整叶片形状更加快捷便利,不仅能够提高离心叶片三维建模精度和效率,而且为叶片三维模型设计及优化提供了帮助。 相似文献
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针对局部协调设计因引入协调曲面而破坏了模型原有的拓扑结构并同时增加了自由曲面形状造型所需的曲面片数量,提出一种基于局部协调设计的复杂裁剪汇交曲面模型拓扑还原技术。逆向定位汇交点(N面角点)并完整构造出决定还原后N边汇交曲面模型拓扑、几何形状和边界的特征曲线网格。应用自由曲面逼近技术分片逼近经裁剪汇交曲面和协调曲面离散获得的点云数据重建B样条曲面以实现裁剪汇交曲面的拓扑还原。采用自由曲面模型的全局美化技术实现紧公差约束下对点云逼近的N张拓扑还原后汇交曲面的全局美化,保证曲面相邻边界和N面角点处收敛的G1光滑拼接。应用实例表明,该拓扑还原技术不仅较好复现了原始汇交曲面模型的拓扑与几何性质,并且使模型达到整体G1连续。 相似文献
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针对航空发动机叶片进排气边的制造精度和一致性较差等问题,搭建了非接触式的叶片进排气边光学测量系统,以实现叶片进排气边的几何尺寸和轮廓形状的快速精确测量。该系统以传统的三坐标测量机框架为平台,采用由两个互成一定角度的新型激光扫描测头构成的专用测头作为前端传感器,并且内置了多种数据后置处理算法。在测量过程中,在每个叶片截面的进排气边处选取5条截线,分别测量这5条截线上的轮廓信息,从而确定叶片进排气边的几何尺寸和加工余量。该系统可以作为叶片加工系统的组成部分,从而将叶片的设计、制造和测量3个环节紧密地联系在一起。最后,应用该系统对某一精锻叶片的3个等高截面上的进排气边进行了多次测量实验,结果验证了所搭建的叶片进排气边光学测量系统的实用性和有效性,而且测量结果的重复性精度能够满足系统的设计要求和叶片进排气边的检测需求。该项研究为叶片进排气边的加工质量提供了一种高效率、高精度和高一致性的评定手段。 相似文献
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Chen-Wei Shan Ding-Hua Zhang Wei-Wei Liu Jun-Xue Ren Xiao-Jun Lin 《The International Journal of Advanced Manufacturing Technology》2009,43(5-6):563-572
This paper aims at developing a novel spiral machining technique for four- or five-axis milling of blades. The main contributions are twofold. First, detailed algorithms are presented to model the blade surface with the idea that it can be separated into four patches, i.e., the pressure surface, the suction surface, the leading edge surface, and the trailing edge surface. The G1 continuity across the boundary of each patch is considered. Second, based on the four patches modeled, the key routine of a new spiral machining method is further addressed in detail. It is carried out by machining the pressure and suction surfaces actually whereas passing by the leading and trailing edges in air cut. Experimental results show that the proposed methods can improve the machining quality and avoid overcut near the leading and trailing edges. 相似文献
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Blades are crucial parts of aero-engines. Their manufacturing is difficult because of their thinness, complex profile and stringent requirements. Electrochemical machining (ECM) is an important approach for manufacturing blades, but it is difficult to machine the leading and trailing edges. This article adopts cross-structural cathodes in ECM to solve the open electric field space problem. The key difficulty in the design of cross-structural cathodes is the position of the crossed-point. The height and the offset of the crossed-point are optimized using the ANSYS software. The simulation results show that the position of the crossed-point obviously affects the machining accuracy, along the leading and trailing edges of the blade. A pair of cross-structural cathodes with one uniform section is designed, and a series of corresponding ECM experiments are carried out. The experiments demonstrate that the ECM process is stable, the profiles are sleek and the machining dimensional error is reduced to 0.08 mm at the leading and trailing edges of the blade when using the new cathode structure. 相似文献
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The objective of the research presented in the paper is the selection of suitable probe radius correction method in the case of coordinate measurements which can be applied for turbine blades. The investigations are based on theoretical analysis of geometric data and on further computer simulation of measurements and data processing. In the paper two methods for computing coordinates of corrected measured points are verified. Those so-called local methods of probe radius correction are based on Bézier curves. They are dedicated first of all to coordinate measurements of free-form surfaces which are characterized by big values of curvature, e.g. those surrounding the leading and trailing edges of a turbine blade. Numerical simulations are done for several models of the cross-sections of turbine blades with diversified magnitudes of radii of curvature. There are considered both manufacturing deviations and coordinate measurement uncertainty of each examined profile of a turbine blade. Numerical investigations based on the developed analytical models show the advantage of the algorithm which uses the second degree Bézier curves in probe radius correction. Moreover, in the paper there is explained the implementation of the developed algorithms for probe radius correction into the standard CMM software which amplifies the usability of the algorithms. 相似文献
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A model reconstruction and CNC tool path generation of broken blades was proposed for the conditions that damage regions locatesd on the leading/trailing edges and on the tips. Measured data points were sorted, adjusted, and then utilized to construct sectional spline curves. The section curve was smoothed based on the theory of minimized energy, a method of aligning the sectional curves according to the curvatures was proposed. A model reconstruction method based on the lofting strategy was presented for the edge broken blades and the tip broken blades. The damaged regions were extracted, based on which the algorithm for generating zigzag tool path and the spiral tool path was given for CNC machining. Preliminary simulation results reveal that the proposed method guarantees the smoothness of the reconstructed surfaces and the approximation to the blade's real size. The feasibility of the proposed tool path generation method was testifiecl. 相似文献
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组合曲面叶片的螺旋加工刀位轨迹生成 总被引:3,自引:0,他引:3
为提高叶片加工质量和改进现有螺旋加工方法,提出了一种新的针对组合曲面造型叶片的四轴螺旋加工方法.该方法在叶片曲面造型过程中,将叶片曲面分割为叶盆、叶背、前缘和后缘四个区域.根据组合曲面叶片造型,提出了组合曲面叶片螺旋加工刀位轨迹生成方法和切触点的计算公式.最后,基于UG软件平台,以二次开发方式编制了相应的数控编程模块.生成了连续光滑的叶片螺旋加工刀位轨迹.试验结果表明,该方法能够实现叶片的四坐标螺旋加工,并可有效提高叶片的加工质量. 相似文献
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航空发动机薄壁叶片精密数控加工技术研究 总被引:12,自引:1,他引:12
加工变形是影响薄壁零件数控加工效率、精度和表面质量的关键性制约因素。本文针对航空发动机薄壁叶片精密数控加工中的变形问题 ,在分析钛合金叶片结构和工艺特点基础上 ,提出了叶片的精确定位方案、以及支撑叶片并控制弹性变形和残余应力变形的有效方法。通过五坐标数控编程和加工试验对新方法进行了验证。测试结果表明 ,采用新方法加工出的叶片满足设计性能要求 ,不但质量上优于传统制造工艺 ,而且制造成本显著降低、周期缩短 6 0 %以上 相似文献
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针对目前航空发动机叶片进排气边加工精度和表面质量较差的问题,提出了一种基于机床运动学约束球头刀多轴加工刀轴矢量优化方法。建立刀位优化变量与刀位数据之间的关系方程,同时建立刀位数据与机床回转轴角度之间的运动变换方程,从而推导出刀位优化变量与机床回转轴角度之间的关系方程。通过求解上述方程得到球头刀多轴加工复杂曲面的刀轴矢量计算公式。在此基础上,给出球头刀多轴加工刀轴矢量优化方法和刀轨生成方法。同时,以某航空发动机叶片为例,分析了本文算法和Sturz算法对机床回转轴角度的影响。分别利用本文算法和Sturz算法生成该叶片进气边加工的刀轨,并在五轴数控机床上进行加工试验。试验结果表明,该算法能够避免加工过程中机床回转轴的大幅波动,使机床轴运动更加平稳和光滑,从而提高曲面的加工质量和加工效率,具有一定的实际应用价值。 相似文献