并联激光切割机床若干关键问题研究

发布时间：2018-01-22 00:20

本文关键词： 并联激光切割机床竖式6-PUS并联机构运动学分析性能分析激光加工试验　出处：《南京航空航天大学》2015年博士论文　论文类型：学位论文

【摘要】：本文研究了目前的激光加工设备,发现驱动激光加工头均采用传统的串联机构,具有刚度差、笨重复杂、累积误差大等缺点。而并联机构作为串联机构的对偶机构,具有刚度大、结构简单、精度高、高速性能好等优点。为此,提出以并联机构作为激光加工头的驱动系统,开发了竖式6-PUS并联激光切割机床,实现了对空间复杂曲面的切割加工。论文首先对竖式6-PUS并联机构的运动学正解和奇异性进行了分析。首次将6-PUS并联机构的位置变量和姿态变量进行了解耦,推导出了其半解析化的正解表达式。根据推导的奇异轨迹解析表达式,分析了各姿态角对位置奇异的影响,得到增大姿态角会减小位置空间的规律。将无奇异姿态球半径作为衡量机构姿态能力(姿态空间)大小的指标,研究了机构参数和位置参数对姿态能力的影响;得出位置偏离中心越远机构的姿态能力越差的结论,并进一步导出姿态能力与偏离距离的近似线性关系表达式。在此基础上,分别从反解和正解的角度分析了6-PUS并联机构的工作空间。对6-PUS并联机构的力传递性能和整体刚度做了分析;基于此,利用“性能图谱和优质尺度域”的机构尺度综合理论对竖式6-PUS并联机构进行了优化设计,得到了优化的机构参数;并以运动/力传递性能为评价指标,对优化前和优化后的机构做了分析比较,结果表明,优化后机构的静平台半径与连杆长度的尺寸相接近,可显著提高机构的运动/力传递性能,同时满足了优质工作空间的设计要求。基于优化的机构,进行了竖式6-PUS并联机构的激光切割机床虚拟样机设计和动力学分析。采用动力学分析软件RecurDyn对其进行运动仿真得到了多种典型运动条件下所需的驱动力,为样机的电机选型提供依据;并利用MFBD多柔体动力学分析技术,对机构进行刚柔混合系统仿真,获得了机构在不同运动模式下的最大应力、应变值,为实际样机的设计提供了参考。最后搭建了竖式6-PUS并联机构的激光切割机床样机,并进行了平板切割和曲面切割实验。通过平板切割的单因素试验和正交实验,探讨了各工艺因素对切割质量的影响,并得到了切割碳钢薄板的较佳工艺参数。最后通过曲面切割,考察机床的固有特性(刚度、各向异性等)对加工精度的影响,为机床的进一步优化提供了依据。
[Abstract]:In this paper, the current laser processing equipment has been studied. It is found that the traditional series mechanism is used to drive the laser machining heads, which has the advantages of poor stiffness and heavy complexity. The parallel mechanism has the advantages of large stiffness, simple structure, high precision and good high-speed performance. Using parallel mechanism as the driving system of laser machining head, a vertical 6-PUS parallel laser cutting machine tool is developed. In this paper, the kinematics positive solution and singularity of vertical 6-PUS parallel mechanism are analyzed firstly. The position and attitude variables of 6-PUS parallel mechanism are firstly analyzed. Decoupling is performed. The semi-analytic positive solution expression is derived and the influence of attitude angles on position singularity is analyzed according to the derived analytic expression of singular locus. The rule that increasing the attitude angle will reduce the position space is obtained. The influence of the mechanism parameters and the position parameters on the attitude capability is studied by taking the spherical radius of the non-singular attitude as the index to measure the attitude capability of the mechanism (attitude space). A conclusion is drawn that the attitude capability of the mechanism farther away from the center is worse, and the approximate linear relationship between attitude capability and deviation distance is derived. On the basis of this, an approximate linear relationship between attitude capability and deviation distance is derived. The workspace of 6-PUS parallel mechanism is analyzed from the point of view of inverse solution and forward solution respectively. The force transfer performance and overall stiffness of 6-PUS parallel mechanism are analyzed. Based on this, the mechanism scale synthesis theory of "performance map and high quality scale domain" is used to optimize the design of the vertical 6-PUS parallel mechanism, and the optimized mechanism parameters are obtained. Taking the performance of motion / force transfer as the evaluation index, the mechanism before and after optimization is analyzed and compared. The results show that the radius of the static platform of the optimized mechanism is close to the dimension of the length of the connecting rod. It can significantly improve the kinematic / force transfer performance of the mechanism and meet the design requirements of the high quality workspace. The virtual prototype design and dynamic analysis of laser cutting machine tool for vertical 6-PUS parallel mechanism are carried out, and several typical kinematic conditions are obtained by using dynamic analysis software RecurDyn to simulate its motion. The driving force you need. It provides the basis for the motor selection of the prototype. Using the MFBD multi-flexible body dynamics analysis technology, the rigid-flexible hybrid system simulation is carried out, and the maximum stress and strain value of the mechanism under different motion modes are obtained. Finally, a prototype of laser cutting machine with vertical 6-PUS parallel mechanism is built. Through the single factor experiment and orthogonal experiment, the influence of each technological factor on the cutting quality is discussed. The optimum technological parameters of cutting carbon steel sheet are obtained. Finally, the influence of the inherent characteristics (stiffness, anisotropy, etc.) of the machine tool on the machining accuracy is investigated through curved surface cutting, which provides the basis for the further optimization of the machine tool.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG485

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