【作者】 张健；

【导师】 赵福令；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 压气机叶轮作为离心压气机的核心零件,是一类典型的复杂曲面零件。它的设计与制造精度直接影响着压气机的性能。随着科学技术的发展,航空航天、船舶、机车等领域对叶轮的转速和设计制造精度的要求日益提高。目前国内对于压气机叶轮的设计与制造主要是引进国外高档的专用软件和五轴数控机床。国外的叶轮加工专用软件一般价格比较昂贵,而且该软件为一封闭的系统,其中的核心技术无法获得。因此,有必要开展离心压气机叶轮五轴高精度数控加工技术的研究,以期进一步提高压气机的性能。 本文从离心压气机叶轮的五轴数控加工流程入手,主要研究了叶轮五轴加工刀具路径规划、特殊类型五轴机床后处理以及误差分析与补偿等技术内容。 分析了离心压气机叶轮的几何结构特点、加工工艺,并在此基础上规划了叶轮的粗、精加工刀具轨迹。在轮毂曲面粗加工方面,提出了将轮毂曲面沿流道方向上分成三个区域,分别采用不同直径刀具进行加工的加工策略,可以有效提高加工效率。在叶片曲面侧铣精加工方面,分析了过切误差,并采用旋转初始刀轴矢量的干涉控制方法,提高了叶片曲面的加工精度。 开发了适合特殊类型五轴数控机床的后处理程序。针对倾斜旋转轴与直线轴不平行的特殊类型五轴数控机床,一般的后处理软件都没有提供这种运动轴方式的后处理功能,为此详细推导了特殊双转台型和双摆头型五轴机床的后处理算法。 分析了叶轮五轴数控加工的非线性误差,指出了其影响因素;提出了利用齐次变换矩阵和正向、逆向运动学相结合的误差计算方法和相应的误差补偿策略以及四元数插值的刀轴矢量“平滑”处理算法,可以进一步提高叶轮加工精度和表面质量。 以一个离心压气机叶轮为例,分别在UG NX软件和DMU 70V五轴机床上进行了计算机仿真加工和试切加工实验。实验结果表明,所提出的算法是正确的和有效的。 本文的研究,实现了离心压气机叶轮的高效高精度五轴数控加工,具有较好的工程实用性;同时,对于其它复杂曲面类零件的五轴加工亦有参考价值。更多还原

【Abstract】 Compressor impeller is a type of representative parts with sculptured surface, which is the most important part in the centrifugal compressor. Its design and manufacture precision have large effect on the performance of compressor. With the development of science and technology, the rotational speed, design and manufacture precision of impeller used in the fields of aeronautics & astronautics, shipbuilding and locomotive are increasing. At the present, major compressor impeller is designed and manufactured with advanced import special software and five-axis NC machine tool. The software system of impeller machining is very expensive and closed package, besides it is impossible for us to acquire its key technology. Therefore, in order to improve the performance of compressor, it is necessary to accomplish the high accuracy five-axis NC machining of centrifugal compressor impeller.Taking the five-axis NC machining workflow of centrifugal compressor impeller as the main thread and tool path scheduling algorithm of five-axis machining, post-processing algorithm for special type of five-axis machine tool and error analysis and compensation algorithm as the core contents are studied.Based on the geometry characteristic and processing technique of centrifugal compressor impeller, the tool path of rough and finish machining are scheduled. During the hub surface rough machining, the first is to divide the hub surface into three local areas along with the direction of flow passage, then the different diameter cutters are utilized to remove materials, which supplies a method to improve the machining efficiency. During the blade surface finish machining, the over-cut error is analyzed and by means of rotating initial tool axis vector to control the interference.Therefore, the impeller machining precision is improved.Post-processing programs for the special type of five-axis NC machine tool is developed to make the full use of five-axis machine tool. The special type of five-axis NC machine tool whose tilt rotary axis and translational axis is not parallel, the generic post-processing software can’t provide post-processing function of specific mode of motion axes, the post-processing algorithm for special table-tilting and spindle-tilting five-axis machine tools is detailed deduced.Based on viewpoint of post-processing, non-linear error of five-axis NC machining of impeller is analyzed and its influencing factors are presented. The error calculating method using the homogeneous coordinate transformation matrix together with forward and inversekinematics and the corresponding error compensation strategies are proposed. Besides, the concept of tool axis vector smoothing is introduced and the quaternion vector interpolation algorithm is proposed, which can improve the impeller machining precision and surface quality further.Finally, taking centrifugal compressor impeller as an example, the proposed methodology is verified by computer machining simulation and a trial machining with the UG NX software and DMU 70V type five-axis NC machine tool. The results indicate the proposed algorithms are correct and valid.The study on high accuracy and high efficiency five-axis NC machining of centrifugal compressor impeller is accomplished and has a favorable value in the engineering application. In addition, the result from the research can be applied in five-axis machining of other sculptured surfaces for reference.更多还原