五轴数控加工刀具与工件误差源建模及控制策略研究
发布时间：2018-11-26 15:36
【摘要】：五轴数控加工技术已经成为先进制造技术和智能装备领域最核心的技术之一,本文沿着高精高速这一数控技术发展的主线,对五轴加工误差的控制策略进行了研究。在对五轴加工误差来源及其分类分析的基础上,归纳出误差控制方法的发展及不足,明确了在数控系统端对加工误差进行控制的研究方向与内容。五轴空间刀具动态补偿是影响来源于刀具误差控制的关键技术,本文对五轴加工过程中的刀具磨损进行建模分析,提出了一种基于开放式数控系统的高效刀具管理技术的刀具磨损动态补偿策略,给出了刀具误差的动态计算、预测、补偿策略。仿真表明,刀具动态补偿技术能够大大减小五轴加工时由刀具磨损引起的误差。将空间刀补与五轴NURBS加工技术有机结合是提高五轴加工精度和速度的难点。本文对五轴加工中的空间刀具补偿技术进行了研究,提出了适用于五轴加工的三重NURBS曲线轨迹模型,通过该模型能够较为完整的描述出刀具位姿和切触点位置,从而能有效的实现五轴空间刀具补偿。试验表明,该方法能够有效解决五轴NURBS加工中的空间刀补问题。基于在机检测的工件模型调整是更通用、直接的工件源误差控制策略。本文在在机检测技术基础上提出了一种工件模型重构调整的误差控制方法,通过对在机检测点的优化选取、重构点的计算以及工件表面的离线重新拟合实现了工件误差的控制,试验表明,该方法在加工刚性较好的工件时对工件误差的控制有明显的效果。误差的在机检测及实时控制是高精高效加工的难点,而轨迹规划则是解决这一问题的关键入手点,本文针对五轴数控加工误差的实时控制提出了一种完整的轨迹规划策略,通过增加轨迹重规划模块克服了宏程序实时补偿不能执行前瞻规划的缺点,给出了完整轨迹规划模块的工作流程。五轴加工中精度与速度是一个传统矛盾点,本文在完整轨迹规划的阶段对加工速度规划方法进行进一步优化,并提出一种能够根据路径类型选择加减速策略的智能S型加减速控制方法,使五轴加工更加平滑,仿真验证表明,使用该智能S型加减速以及变插补周期精插补技术,能够在保证原有的加工精度前提下提高加工速度。对本文所提出的五轴数控加工误差控制策略进行实际验证,在通用五轴数控系统软硬件架构基础上,提出两种平台方案,研制出一种五轴数控系统样机,并通过试验验证基于本文误差控制策略的五轴数控系统能够显著提高五轴加工的精度和加工速度。
[Abstract]:Five-axis NC machining technology has become one of the core technologies in the field of advanced manufacturing technology and intelligent equipment. In this paper, the control strategy of five-axis machining error is studied along with the development of high-precision and high-speed NC technology. Based on the analysis of the source and classification of five-axis machining error, the development and deficiency of error control method are summarized, and the research direction and content of machining error control at the end of NC system are clarified. The dynamic compensation of five-axis space tool is the key technology that affects the tool error control. In this paper, the tool wear in the five-axis machining process is modeled and analyzed. A dynamic compensation strategy of tool wear based on efficient tool management technology of open NC system is presented. The dynamic calculation, prediction and compensation strategy of tool error are given. Simulation results show that the tool dynamic compensation technique can greatly reduce the error caused by tool wear in five-axis machining. It is difficult to improve the precision and speed of five-axis machining by combining spatial cutter compensation with five-axis NURBS machining technology. In this paper, the spatial tool compensation technology in five-axis machining is studied, and a three-fold NURBS curve trajectory model suitable for five-axis machining is proposed. Through the model, the position and position of cutting point can be described completely. Thus, the five-axis space tool compensation can be realized effectively. The experimental results show that the method can effectively solve the spatial cutter compensation problem in five-axis NURBS machining. The adjustment of workpiece model based on in-machine detection is a more general and direct control strategy of workpiece source error. In this paper, an error control method for reconfiguration of workpiece model is proposed on the basis of machine testing technology. The control of workpiece error is realized by optimizing selection of in-machine inspection point, calculation of reconfiguration point and off-line refitting of workpiece surface. The experiment shows that the method has obvious effect on controlling the workpiece error when machining the workpiece with good rigidity. In-machine error detection and real-time control are the difficulties of high-precision and high-efficiency machining, and trajectory planning is the key point to solve this problem. In this paper, a complete trajectory planning strategy is proposed for real-time control of five-axis NC machining errors. By adding trajectory replanning module, the shortcomings of real-time compensation of macro program can not perform forward planning are overcome, and the work flow of the complete trajectory planning module is given. Precision and speed are a traditional contradiction in five-axis machining. In this paper, the machining speed planning method is further optimized in the stage of complete trajectory planning. An intelligent S-type acceleration and deceleration control method which can select acceleration and deceleration strategy according to path type is proposed to make the five-axis machining smoother. The simulation results show that the intelligent S-type acceleration and deceleration and variable interpolation cycle precision interpolation techniques are used. It can improve the machining speed under the premise of guaranteeing the original machining precision. The error control strategy of five-axis NC machining is verified in this paper. On the basis of the hardware and software architecture of general five-axis NC system, two kinds of platform schemes are proposed, and a prototype of five-axis NC system is developed. The experiments show that the five-axis NC system based on the error control strategy in this paper can significantly improve the precision and speed of five-axis machining.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG659
[Abstract]:Five-axis NC machining technology has become one of the core technologies in the field of advanced manufacturing technology and intelligent equipment. In this paper, the control strategy of five-axis machining error is studied along with the development of high-precision and high-speed NC technology. Based on the analysis of the source and classification of five-axis machining error, the development and deficiency of error control method are summarized, and the research direction and content of machining error control at the end of NC system are clarified. The dynamic compensation of five-axis space tool is the key technology that affects the tool error control. In this paper, the tool wear in the five-axis machining process is modeled and analyzed. A dynamic compensation strategy of tool wear based on efficient tool management technology of open NC system is presented. The dynamic calculation, prediction and compensation strategy of tool error are given. Simulation results show that the tool dynamic compensation technique can greatly reduce the error caused by tool wear in five-axis machining. It is difficult to improve the precision and speed of five-axis machining by combining spatial cutter compensation with five-axis NURBS machining technology. In this paper, the spatial tool compensation technology in five-axis machining is studied, and a three-fold NURBS curve trajectory model suitable for five-axis machining is proposed. Through the model, the position and position of cutting point can be described completely. Thus, the five-axis space tool compensation can be realized effectively. The experimental results show that the method can effectively solve the spatial cutter compensation problem in five-axis NURBS machining. The adjustment of workpiece model based on in-machine detection is a more general and direct control strategy of workpiece source error. In this paper, an error control method for reconfiguration of workpiece model is proposed on the basis of machine testing technology. The control of workpiece error is realized by optimizing selection of in-machine inspection point, calculation of reconfiguration point and off-line refitting of workpiece surface. The experiment shows that the method has obvious effect on controlling the workpiece error when machining the workpiece with good rigidity. In-machine error detection and real-time control are the difficulties of high-precision and high-efficiency machining, and trajectory planning is the key point to solve this problem. In this paper, a complete trajectory planning strategy is proposed for real-time control of five-axis NC machining errors. By adding trajectory replanning module, the shortcomings of real-time compensation of macro program can not perform forward planning are overcome, and the work flow of the complete trajectory planning module is given. Precision and speed are a traditional contradiction in five-axis machining. In this paper, the machining speed planning method is further optimized in the stage of complete trajectory planning. An intelligent S-type acceleration and deceleration control method which can select acceleration and deceleration strategy according to path type is proposed to make the five-axis machining smoother. The simulation results show that the intelligent S-type acceleration and deceleration and variable interpolation cycle precision interpolation techniques are used. It can improve the machining speed under the premise of guaranteeing the original machining precision. The error control strategy of five-axis NC machining is verified in this paper. On the basis of the hardware and software architecture of general five-axis NC system, two kinds of platform schemes are proposed, and a prototype of five-axis NC system is developed. The experiments show that the five-axis NC system based on the error control strategy in this paper can significantly improve the precision and speed of five-axis machining.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG659
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