焊接叶盘根部区域适应性数控加工技术研究

发布时间：2018-06-18 04:44

本文选题：焊接叶盘 + 在机测量　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：整体叶盘是航空发动机关键部件,随着发动机性能要求的提高,新型的焊接叶盘被广泛采用。该类型叶盘具有结构重量轻、零件数量少、气动效率高等优点,可使发动机结构大为简化,但其前期的焊接偏差给叶盘焊接毛坯后续的精确数控加工带来了极大的困难。针对该数控加工困难的问题,本文研究了一种适应性数控加工技术,包括接触式在机测量、基于测量数据的适应性曲面建模和叶片根部区域加工刀轨再生成等研究内容,提出一种适合AC双转台五轴联动数控机床的接触式在机测量程序生成方法,实现基于测量数据与叶片根部区域理论模型相混合的曲面适应性建模以及基于曲面映射的加工刀轨生成和优化方法,解决按照传统数控加工工艺对叶盘焊接毛坯进行数控加工出现的“台阶”、过切以及无法自动生成叶片根部区域加工刀轨等问题。本文主要研究内容:(1)研究了一种AC双转台五轴联动数控机床对焊接叶盘的接触式在机测量技术。主要包括测头的设定、测量点的采样、测量路径的规划以及在机测量程序生成等。通过生成的测量程序对叶片根部区域进行在机测量,并将获得的测量数据进行数据处理,最终可得到测头与实际叶片接触的实际接触点。(2)研究了曲线曲面建模技术。对于实际测量曲线建模,本文采用了具有公差约束的三次曲线来拟合测量数据不仅可以使曲线尽量通过实际接触点,而且可以保证曲线的光顺性;对适应性曲面建模,本文选择焊台内部一条理论截面曲线和叶片已有型面上两条实际测量曲线,利用这三条曲线来构根部区域的适应性曲面。(3)研究了基于参数曲面映射的加工刀轨再生成技术。首先根据叶片曲面的特点采用以截面线为基础的UV参数域来建立根部区域理论曲面与适应性曲面之间映射关系,其次通过刀位轨迹映射获得适应性曲面的加工刀轨,然后提出基于弧弦误差比较的刀轨步长调整方法和基于局部刀轴姿态二阶连续的刀轴矢量光顺算法,使得刀轨的最大误差和刀轴矢量变化符合要求。最后利用焊接叶盘适应性数控加工系统成功完成了对焊接叶盘测量和加工的实验,验证了该系统生成的测量程序和加工代码的可靠性和相关算法的有效性。
[Abstract]:Integral impeller is the key component of aero-engine. With the improvement of engine performance, the new welding vane is widely used. This type of disc has the advantages of light structure, small number of parts and high aerodynamic efficiency, which can greatly simplify the engine structure. However, the welding deviation in the early stage brings great difficulties to the subsequent accurate NC machining of the blank welding of the blade disk. Aiming at the difficult problem of NC machining, this paper studies a kind of adaptive NC machining technology, including contact-in-machine measurement, adaptive surface modeling based on measurement data and tool track re-generation in blade root area. In this paper, a method of generating in-machine contact measuring program is presented, which is suitable for AC double turntable five-axis linkage NC machine tool. The surface adaptive modeling based on measuring data and the theoretical model of blade root region is realized, and the machining tool track generation and optimization method based on surface mapping is realized. To solve the problems of "step", over-cutting and non-automatic generation of cutting track in machining blade disk welding blank according to the traditional NC machining technology. This paper mainly studies the measurement technology of AC double turntable five-axis linkage NC machine tool for welding vane disk. It mainly includes the setting of probe, sampling of measuring point, planning of measuring path and generating of measuring program in machine. Finally, the actual contact point between the probe and the actual blade can be obtained. Finally, the modeling technology of curve and surface is studied. For the modeling of actual measurement curve, the cubic curve with tolerance constraint is used to fit the measured data, which can not only make the curve pass through the actual contact point as much as possible, but also guarantee the smoothness of the curve. In this paper, a theoretical section curve and two actual measuring curves on the existing blade surface are selected. Using these three curves to construct the adaptive surface of the root region, the machining tool track reconstruction technology based on parametric surface mapping is studied. Firstly, according to the characteristics of blade surface, UV parameter domain based on section line is used to establish the mapping relationship between the theoretical surface of root region and the adaptive surface. Secondly, the machining tool track of adaptive surface is obtained by tool path mapping. Then, a method of adjusting the tool path step size based on the comparison of arc chord errors and a second-order continuous tool axis vector smoothing algorithm based on the local cutter axis attitude are proposed, which make the maximum error of the tool track and the variation of the tool axis vector meet the requirements. Finally, the experiments of measuring and machining the welded vane are successfully completed by using the adaptive NC machining system of welded vane, which verifies the reliability of the measurement program and machining code generated by the system and the validity of the related algorithms.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659

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