数控机床工作精度检验中的运动控制指标作用机理研究

发布时间：2018-07-05 15:27

  本文选题：五轴数控机床 + 工作精度检验　； 参考：《电子科技大学》2015年博士论文

【摘要】：随着现代制造技术的快速发展,数控机床已经成为不可或缺的重要设备,而高速高精度五轴数控机床的应用已经成为提升制造业技术水平及高科技发展的重要标志。在复杂零件的高速精密加工中,五轴数控机床的运动性能成为影响工件质量的关键因素和机床等级评价的重要指标。通过切削试件轮廓误差的表现反映运动控制指标的作用度,以指导机床调整和工艺优化,保障五轴数控机床最终加工精度有着十分重要意义。本文从数控机床的工作精度检验标准出发,对五轴数控机床加工过程中的轮廓误差形成机理,数控机床伺服特性和控制系统的控制特性对运动轨迹、运动性能和加工精度的影响进行了研究。采用一种基于前瞻算法的多轴运动的轴速度规划策略,建立了五轴联动数控机床运动控制参数影响试件切削速度、加速度以及加工精度的模型,揭示了试件在高速高精度加工中异常刀痕形成机理,探索了多轴联动高速加工数控机床工作性能评价新途径,为利用复杂形面试切结果评价数控机床的工作性能提供了理论依据。研究过程中主要开展了以下几个方面的工作并得到相关的研究成果。(1)论文首先研究了五轴数控加工中的试件轮廓误差形成机理,分析了数控机床加工误差的主要来源,论述了五轴数控机床的轴跟随误差对试件轮廓误差形成的作用机理。针对五轴数控机床由于旋转轴的引入导致的刀尖运动轨迹的复杂变化,运用了多体运动理论以及齐次坐标变换理论,推导了五轴数控加工中的复杂形面的轴跟随误差与轮廓误差的映射关系。(2)由于数控机床的伺服特性是影响单轴跟随误差的主要因素,本文根据数控机床的平动轴、旋转轴伺服驱动装置和机械传动机构的结构特点,建立了这两种形式的伺服机构动力学模型,研究数控机床伺服性能指标对各坐标轴误差的影响,特别是旋转轴伺服特性对轮廓误差的影响。针对工作精度检验中常见的圆弧轨迹的多轴联动运动情况,分别对平动轴与旋转轴联动、两个旋转轴联动两种联动方式进行了讨论,从伺服系统的刚度、增益、伺服时间常数、反向间隙等指标对轮廓误差的影响以及各轴参数之间匹配关系进行了系统的分析。(3)研究了数控系统的控制方法、运动极限参数对坐标轴误差的影响。由于坐标轴跟随误差与轴运动速度相关,即受坐标轴指令值的直接影响,而坐标轴指令又受数控系统插补算法,加减速控制方式及运动极限参数,前瞻算法等多因素影响,使得伺服系统接收的各坐标轴指令与编程的G代码指令有较大不同,不能简单按照试件成形机理分解成各坐标轴指令,因此,本文采用了一种动态规划的进给速度规划策略来计算坐标轴指令,对高速高精度复杂形面加工中,微小段多,转折和拐点多等情况下的进给速度实施规划和轴指令值的求解,并分析了控制系统加速度、加加速度、最大速度等极限参数对轴进给速度和轨迹运动误差的影响,以及这些极限参数的作用权重,从而建立高速加工中数控机床的控制指标影响复杂曲面轮廓误差的理论体系。(4)针对工作精度检验中常用的国际标准NAS试件和“S”形试件的试件切削检验中的运动轨迹误差进行了计算、仿真和实验设计,研究了数控机床实际运动性能的表现,以及运动控制指标对加工精度的影响。通过NAS试件的仿真切削研究,分析了试件加工精度所映射的多轴联动机床伺服性能指标和运动控制指标作用规律;以“S”形试件侧铣加工的过程为研究对象,从试件构造的曲面特性出发,分析了五轴数控加工的编程代码特点,对侧铣加工表面切削速度受数控机床的加速度、加加速度等运动控制参数影响的平稳性进行了分析,通过伺服进给系统模型获得跟随误差,并对侧铣加工的异常刀痕的形成进行了演绎。通过仿真和实验,得到“S”形试件侧铣加工异常刀痕的机床运动控制指标作用规律,为数控机床工作精度检验中试件构造设计和利用试件切削误差来检验机床运动性能提供参考依据。本课题来源于国家04重大科技专项“国产高档数控机床在典型飞机结构件加工中的示范应用”,项目编号2010ZX04015-011,课题研究成果部分用于校验机床的运动性能,指导机床维修和调整,优化加工方案;同时为制定五轴数控加工动态精度测试规范,为高速高精度五轴联动数控机床的研制和工作性能分析提供理论依据。
[Abstract]:With the rapid development of modern manufacturing technology, CNC machine tool has become an indispensable important equipment, and the application of high speed and high precision five axis CNC machine tool has become an important symbol to improve the technology level of manufacturing industry and the development of high technology. In the high speed precision machining of complex parts, the motion performance of five axis CNC machine tool has become the influence worker. The key factor of the quality of the parts and the important index of the evaluation of the machine tool grade. It is very important to guide the adjustment of the machine tool and the process optimization by the representation of the contour error of the cutting specimen, to guide the adjustment of the machine tool and the process optimization, and to ensure the final machining precision of the five axis CNC machine tools. The formation mechanism of the contour error in the processing of five axis CNC machine tools, the influence of the servo characteristics and control characteristics of the CNC machine tools on the motion trajectory, the motion performance and the machining precision are studied. The motion control of the five axis CNC machine tool is established by using a multi axis motion planning strategy based on the forward looking algorithm. The model of the parameters affecting the cutting speed, acceleration and machining precision reveals the formation mechanism of the abnormal knife marks in high speed and high precision machining, explores a new way to evaluate the performance of the CNC machine tools with multi axis linkage and high-speed machining, and provides a theoretical basis for the evaluation of the working performance of the CNC machine tool by using the results of complex interviewing and cutting. The following work is carried out in the following aspects and the relevant research results are carried out. (1) first, the paper studies the formation mechanism of the profile error in the five axis NC machining, analyzes the main source of the machining error of the NC machine tool, and discusses the action machine of the axis following error of the five axis NC machine tool to the outline error of the specimen. In view of the complicated changes in the trajectory of the blade tip caused by the introduction of the rotating axis in the five axis CNC machine tool, the multi body motion theory and the homogeneous coordinate transformation theory are applied to deduce the mapping relation between the axis following error and the contour error of the complex surface in the five axis NC machining. (2) the servo characteristics of the CNC machine tool are the single axis. Following the main factors of the error, based on the structural characteristics of the translational axis, the rotating shaft servo drive device and the mechanical transmission mechanism of the CNC machine tools, the dynamic model of the two forms of servo mechanism is established, and the influence of the servo performance index on the coordinate axis error is studied, especially the rotation axis servo characteristics to the contour error. In view of the multi axis linkage movement of the common circular arc trajectory in the work precision test, the linkage between the translational axis and the rotating axis and the two linkage modes of the two rotation axes are discussed respectively. The influence of the stiffness, gain, servo time constant and reverse clearance on the contour error and the matching of the parameters of the axis of the servo system are discussed. The system analysis is carried out. (3) the control method of numerical control system is studied, and the influence of the motion limit parameters on the coordinate axis error is studied. The coordinate axis following error is related to the axis motion speed, that is, the direct influence of the coordinate axis instruction value, and the coordinate axis instruction is also affected by the numerical control system interpolation algorithm, the acceleration and deceleration control mode and the motion limit. With the influence of many factors, such as parameters and forward looking algorithms, the coordinate axis commands received by the servo system are different from the programmed G code instructions. It can not be simply divided into coordinate axis instructions according to the forming mechanism of the specimen. Therefore, a dynamic programming strategy of feed speed planning is adopted to calculate the coordinate axis instruction, and the high speed and high precision is used in this paper. In the processing of complex surface, the feed speed under the circumstances of many small segments, turning points and many turning points is solved, and the influence of the limit parameters such as acceleration, adding speed and maximum velocity on the axis feed speed and track motion error are analyzed, and the action weight of these limit parameters is established, and the high speed is established. The control index of NC machine tool in processing affects the theory system of the contour error of complex curved surface. (4) calculation, simulation and experimental design are carried out for the motion trajectory error of the test parts of the international standard NAS test parts and the "S" shaped specimen, which are commonly used in the inspection of the work precision. The simulation and experimental design are designed, and the performance of the actual motion performance of the NC machine tool is studied and the performance of the numerical control machine is studied. The influence of the motion control index on the machining precision. Through the simulation cutting research of the NAS specimen, the servo performance index and the motion control index of the multi axis linkage machine tool mapped by the test parts are analyzed. The process of the side milling of the "S" shaped specimen is taken as the research object, and the five axis is analyzed from the surface characteristics of the specimen structure. The programming code characteristics of NC machining are analyzed. The stability of the cutting speed of side milling is influenced by the acceleration of CNC machine tools, adding speed and other motion control parameters. The following error is obtained by the servo feed system model, and the formation of abnormal knife marks in the side milling process is deducted. The simulation and experiment results are obtained. The action rule of the motion control index of the machine tool of "S" shaped specimen with abnormal knife marks is provided for the structural design of the test parts of the CNC machine tool and the use of the cutting error to test the motion performance of the machine tool. This topic is derived from the national 04 major science and technology special machine tool in the typical aircraft structure. The project number 2010ZX04015-011, the project number is used to verify the motion performance of the machine tool, to guide the maintenance and adjustment of the machine tool, to optimize the processing scheme, and to formulate the dynamic precision test specification for the five axis NC machining, and to analyze the development and performance analysis of the high speed and high precision five axis CNC machine tool. For theoretical basis.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG659
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本文编号：2100703