【作者】 张威；

【导师】 赵东标；

【作者基本信息】 南京航空航天大学 ， 机械电子工程， 2009， 博士

【摘要】 先进制造技术代表着制造业领域的发展方向,数控技术则是当今先进制造技术和装备中最核心的技术之一,世界上各发达国家都将数控技术以及数控装备列为国家的战略物资。复杂曲线曲面插补技术是数控技术研究中的关键,这些技术目前只被少数国际大公司,如FANUC、Siemens等所掌握。我国国内具备复杂曲线曲面插补功能的中高档数控系统目前还主要依赖进口,而且这些进口的技术设备多被进行了“技术封闭”,用户只有使用权限,而对于其中的关键算法、代码都无法掌握。本论文在江苏省自然科学基金(招标)项目(BK2003005)的资助下,对位模式插补的算法原理及算法实现进行了深入细致的研究,并以位模式插补技术为核心进行扩展,研究了复杂曲线曲面加工中若干关键技术问题,提出了一种复杂曲线曲面位模式插补算法,为提高具有我国自主产权的数控技术水平提供了新的尝试。论文的主要研究内容如下。对位模式插补算法原理进行了研究并且给出了利用控制器中断功能实现位模式插补的方法,包括位模式插补脉冲周期的设定以及插补脉冲的发送。在位模式插补原理的基础上提出了位模式插补速度控制方法并分别采用梯形加减速法和S型加减速法对位模式插补数据进行了速度规划。根据位模式插补算法原理,提出了一种误差可控复杂曲线位模式插补的插补数据生成算法。在先给出了较为简单的直线段位数据生成方法的基础上,针对复杂列表曲线分别用三次B样条曲线和三次参数曲线进行拟合,重建刀位点轨迹线;然后,在最大误差的控制之下对刀位轨迹进行了离散;最后,用直线段插补数据进行位数据生成。针对笔式加工这一目前曲面加工技术中的前沿问题进行了讨论,指出了笔式加工技术目前存在的若干问题。针对这些问题,将位模式插补技术引进到笔式加工技术中,建立起一套以笔式加工和位模式插补为核心技术的复杂曲面上自由曲线三坐标插补模块。针对复杂曲面笔式加工中参数曲面之间求交运算困难的问题,将笔式加工分为小局部区域和局部区域两种情况进行讨论。对于小局部区域,是将目的导引线的起始点映射到曲面的局部待加工区域之上,然后按照目的导引线的位插补数据,以该点为起始点进行插补运算;对于一般的局部区域,首先对目的导引线进行数据离散化,在允许误差的约束下生成数据离散点,然后求出这些离散点在加工曲面上的映射点,最后针对这些映射点的连线进行位数据生成进而实现曲面加工。接着,将位模式插补的应用扩展到整体曲面加工之中。利用等参数法对曲面进行轨迹规划,然后依次对等参数线进行位模式数据生成,实现对整体曲面的加工。通过上述研究,建立起一套复杂曲线曲面三坐标位模式插补加工方法。针对五坐标笔式加工中刀轴定位问题展开研究。深入分析了笔式加工两种加工情况的特点,分别为这两种情况选择加工刀具,并制定了无干涉刀轴定位策略。提出了一种新的刀轴矢量函数的生成算法,可以保证全局刀轴矢量连续光顺。在此基础上,将位模式插补算法引入到五坐标笔式加工中,对三坐标位数据生成算法进行扩展,提出了一种五坐标位数据生成算法。通过上述研究,建立起一套复杂曲线曲面五坐标位模式插补加工方法。针对五坐标位模式插补中的非线性误差控制问题进行研究。首先,建立了五坐标加工非线性误差模型,分析了非线性误差的产生原因,然后,通过对比分析国内外关于非线性误差控制的相关技术,指出了存在的问题。将RTCP方法引入到五坐标位模式插补计算中,通过将RTCP算法和通常的非线性误差控制算法进行比较,得出结论:RTCP算法不仅可以有效降低非线性误差,还可以避免由于局部加工步长调整而带来的反复修改整个加工程序的问题。更多还原

【Abstract】 Advanced manufacturing technology represents the developing direction of the manufacturing technology, while the CNC technology is the most important technology in the family of advanced manufacturing technologies and equipments. The CNC technology and equipments are the strategic materials in many developed countries. The interpolating technology of complex curves and surfaces is the key technology in the CNC technologies and it’s mastered only by a few big companies in the world, such as FANUC and Siemens. Nowadays, most of the high performance CNC systems of our country are imported from foreign countries. The kernel technologies in these systems are closed to the users and it is not helpful for the CNC development of our country.This dissertation is supported by Natural Science Foundation of Jiangsu Province (Code: BK2003005). The principle and implementation of the bit pattern algorithm are studied in the dissertation, and many key technical problems are solved. One type of algorithm of bit pattern interpolation (BPI) of complex curves and surfaces is developed. A new way for the development of the CNC technology has independent intellectual property right in China. The mainly research achievements are shown as following.The principle of the BPI algorithm is researched and the algorithm is implemented by using interrupt function of controller. A velocity control algorithm of the BPI is presented. An error-controllable BPI data-generating algorithm is proposed. Firstly, the tool-path was built according to the key points of the machining curve. Parametric cubic spline was used to fit these key points. Then, the tool-path was dispersed into many line segments. To ensure the calculation accuracy, the equation reflecting the relation between the maximum allowable error and the segment number was deduced. The discrete ratio was based on the equation. At last, the BPI data was generated according to these line segments.The front questions of the curve machining technology and pen cutting algorithm of sculptured surface are discussed and the problems of the machining technology of complex curves and surfaces are analyzed. Furthermore, some key problems are pointed out. To solve these problems, the BPI algorithm is introduced into the pen cutting technology. Aiming at the problem of surface intersection operation in the pen cutting, the pen cutting is divided into two conditions, micro local-area cutting and general local-area cutting. For micro local-area cutting, the starting point of the objective driving curve is mapped to the machining area and the bit pattern data is generated according to the objective driving curves. The machining is finished based on the starting point and the bit pattern data. For general local-area cutting, the objective driving curve is dispersed into many short segments in the error range. Then, the endpoints of these short segments are mapped to the machining area, and the bit pattern data is generated according to the connecting lines of the mapping points. Furthermore, the BPI algorithm is introduced into the surface global processing technology. Iso-parametric method is used to make the tool-path plan firstly. Then, the bit pattern data of the iso-parametric curves is generated and the machining is performed according to the bit pattern data. A whole three-coordinate interpolating module of complex curves and surfaces is built according to above research.The problem about tool locating is also studied in the dissertation. Two terms of the pen cutting are researched and different tool locating strategies are made according to the terms. A tool-axis vector generating algorithm is proposed. The algorithm can ensure the continuity and smoothness of the global tool-axis vector. The BPI algorithm is introduced into the five-axis pen cutting, and a data generating algorithm of the five-axis BPI is presented. A whole five-axis interpolating module of complex curves and surfaces is built according to above research.The nonlinear error controlling problem in the five-axis machining is studied. The reason of the nonlinear error production is analyzed and the existing problems of the general error control methods are pointed out. The RTCP method is introduced into the five-axis BPI. By comparing the RTCP method with the general error control method, a conclusion is drawn that the RTCP method can not only control the nonlinear error effectively but also avoid the problem of repeated modification of processing program.更多还原