轴流式闭式叶轮的五轴高速加工工艺策略研究

发布时间：2018-05-05 12:08

本文选题：闭式叶轮 + 高速铣削　；参考：《陕西科技大学》2017年硕士论文

【摘要】：在透平机械领域中,通常选用整体结构性好,强度高的轴流式闭式叶轮作为工作部件,从而提高设备的运转性能。但由于闭式叶轮结构复杂,流道扭曲剧烈,叶片间空间狭小,加工要求高,所以轴流式闭式叶轮的刀位规划难度高,加工难度大。在制造业中,通常采用焊接的方式,通过分部加工叶轮的部位,然后组合在一起,最后完成叶轮的制造。采用这种组合式加工工艺,不利于提高加工效率,在产品制造周期中所占的比重很大,而且叶轮的结构参数、工作性能都无法得到保证。所以采用五轴数控加工技术、高速铣削技术、以及高端的CAM软件技术,对轴流式闭式叶轮的五轴高速铣削加工工工艺进行系统的研究,对提高这类结构复杂、零件整体刚性差的产品加工效率和加工质量有很好的借鉴意义。首先,为了保证轴流式闭式叶轮的建模精度,对建模原理和技术进行分析研究,采用三次B样条技术,用MATLAB软件反求出叶轮的控制点,将计算的控制点数据导入UG软件,在UG软件中完成闭式叶轮的叶片曲面、轮毂面、包覆面的建模,为后续的CAM编程以及相关数学计算做好了铺垫。其次,对五轴高速铣削加工技术进行分析,对轴流式闭式叶轮的加工要求和加工难点进行分析,确定加工步骤,初始毛坯的结构、加工使用的刀具、夹具安全高度的计算、夹具的设计,设计加工工艺卡,从而完成轴流式闭式叶轮的加工工艺规划。再次,采用数学计算方法,利用MATLAB软件完成了轴流式闭式叶轮流道的最大内接圆柱面的计算,确定了定轴粗加工的范围,用金属有限元切削分析仿真软件确定了切削前角的范围,最后用定轴加高速铣削的方式完成闭式叶轮的刀位轨迹规划。粗加工完成后,针对残留量不均匀,残留量较多的问题,采用余量偏置、分层叠加的刀位轨迹规划方式,结合CAM软件的管道模块加工原理,完成半精加工的刀位轨迹计算。在半精加工的CAM设置里,改变精加工切削参数,完成刀位轨迹的计算,在精加工插补方面,采用五轴样条插补代替直线插补,对三次多项式样条插补的原理、计算步骤进行了深入的研究,设计了五轴样条插补流程图。最后,通过CAM软件HyperMill结合以上各阶段研究的刀位规划成果,分别对轴流式闭式叶轮的各个加工阶段,按照加工工艺的顺序完成CAM编程,完成刀位轨迹的计算,然后将HyperMill的mof刀位文件转换成APT文件,利用UG的后处理模块开发五轴样条插补后处理,运用Tcl语言编写相关的后处理程序语句,编写完成后对刀位文件进行后处理,然后在仿真模拟软件上模拟NC程序,最后在机床上对轴流式闭式叶轮进行实际加工验证,证明了轴流式闭式叶轮的加工工艺正确性。
[Abstract]:In the field of turbine machinery, the axial flow closed impeller with good overall structure and high strength is usually chosen as the working part, thus improving the operation performance of the equipment. But because the structure of the closed impeller is complex, the flow channel is distorted violently, the space between the blades is narrow, and the machining requirement is high, the tool position planning of the axial flow closed impeller is difficult and the processing difficulty is great. In manufacturing, welding is usually adopted, the parts of impeller are processed by parts, then assembled together, finally the manufacture of impeller is finished. This kind of combined processing technology is not conducive to improving the processing efficiency and occupies a large proportion in the manufacturing cycle of the product, and the structural parameters and the working performance of the impeller cannot be guaranteed. Therefore, five-axis NC machining technology, high-speed milling technology and high-end CAM software technology are used to systematically study the five-axis high-speed milling process of axial flow closed impeller, which is complex to improve this kind of structure. The machining efficiency and quality of parts with poor overall rigidity are of great significance. First of all, in order to ensure the modeling accuracy of the axial flow closed impeller, the modeling principle and technology are analyzed and studied. The control points of the impeller are obtained by using the cubic B-spline technique and the MATLAB software, and the calculated data of the control points are imported into UG software. The modeling of the blade surface, hub surface and cladding surface of the closed impeller is completed in UG software, which lays the groundwork for the subsequent CAM programming and related mathematical calculation. Secondly, the processing technology of five-axis high speed milling is analyzed, the machining requirements and difficulties of axial flow closed impeller are analyzed, the processing steps, the structure of initial blank, the tool used for machining, the safety height of fixture are calculated. Jig design, design processing process card, so as to complete the axial flow closed impeller processing process planning. Thirdly, by using the mathematical calculation method and using MATLAB software, the calculation of the maximum inner connection cylinder surface of the axial flow closed impeller runner is completed, and the range of the fixed axis rough machining is determined. The range of cutting front angle is determined by the metal finite element cutting simulation software. Finally, the tool path planning of closed impeller is completed by means of fixed axis and high speed milling. After rough machining, aiming at the problem of uneven residue and more residue, the tool path planning method of residual bias and stratified superposition was adopted, and the tool path calculation of semi-finished machining was completed by combining the pipe module machining principle of CAM software. In the CAM setting of semi-finished machining, the cutting parameters are changed to complete the calculation of the tool path. In the interpolation, the five-axis spline interpolation is used to replace the linear interpolation, and the principle of cubic polynomial spline interpolation is given. A five-axis spline interpolation flow chart is designed. Finally, the CAM software HyperMill is used to complete the CAM programming according to the sequence of the machining technology to complete the calculation of the tool position trajectory for each processing stage of the axial flow closed impeller by combining the tool position planning results of the above stages. Then the mof tool position file of HyperMill is converted into APT file, the five axis spline interpolation post processing is developed by UG post processing module, and the relevant post processing program statements are written by Tcl language, and the tool position file is processed after the completion of the program. Then the NC program is simulated on the simulation software. Finally, the machining technology of the axial flow closed impeller is verified by actual machining on the machine tool, which proves that the machining technology of the axial flow closed impeller is correct.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659;TK14

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