哈尔滨工业大学工学博士学位论文
空间误差，实验验证了补偿的有效性。依据辨识得到的伺服参数，调整系统动态适配时间，机床圆轨迹误差降低了80%。开展了热漂移误差补偿装置在西门子数控系统中的应用方法研究，补偿前后的对比结果验证了补偿系统的稳定有效性。最终，将误差补偿技术综合应用到重型数控落地铣镗床中，补偿效果显著，加工误差降低35%以上。
关键词：落地铣镗床；综合误差建模；分区测量；滑枕热变形；误差补偿
- II -
Abstract
Abstract
Heavy CNC milling and boring machine is suitable for large size parts machining and the application of this machine tool is limited due to its inaccuracy. It has important practical significance to control and compensate error effectively for machine tool. However, the research on accuracy measurement and error compensation for machines is still far from the end.
In this paper, traceable error analysis of heavy-duty CNC milling and boring machine is carried out. The coupling mechanism of geometric and thermal error is introduced. The synthetic error model containing geometric and thermal coupling error and dynamic error is established. The error sensitivity matrix is developed.
The error measurement uncertainty is analyzed and the method for precision retaining is developed. Error measurement in multi-station is proposed with workspace segment based on laser tracker. The distribution of measurement uncertainty of components is discovered according to the experimental result. Thermal drift error is the main error when the temperature of machine tool raises little through machine thermal experiment, and themal drift error of spatial point is modeled. The effect of machine repeatability on uncertainty is analysed. The measurement uncertainty is estimated by Monte Carlo method according to laser tracker. In order to decrease measurement uncertainty, the measurement system station is optimized. The measurement in multi-station is proposed with workspace segment, which are proved validity by comparing with experiment result.
Geometric error is identified based on measurement in multi-station. Sensitivity of volumetric error about geometric errors is analysed, as well as the influence of spatial dimensions on sensitivity based on error sensitive matrix. An error identification methodology based on four-line measurement and spatial point measurement is proposed. The particle swarm optimization (PSO) is brought in. The squareness error, linear displacement error, angle error are identified respectively. The method is proved validate through comparing with the results measured by laser interferometer.
The tracking error of the servo system and the circular trajectory contour error are modeled for identifying error parameters. The circular trajectory distribution is analysed by actual measurement results of XY circle. The method for decoupling dynamic error and the quasi static error is researched. The parameters of servo system are identified based on contour error model and servo error decoulped. The prediction accuracy is verified.
- III -
哈尔滨工业大学工学博士学位论文
The prediction accuracy of sythetical error model is verified based on the error parameters identified. Volumetric error in Z-axis is analysed based on finite element method (Anasys) and experiment. The source of Z-axis thermal drift error is discovered based on the establishement of the error chain of thermal deformation of the spindle box. The mature commercialization error real-time measurement and compensation system is developed based on Invar alloy rod.
Based on error compensator developed for Simense NC system, the volumetric error is compensated, which demonstrates the compensation validity by comparing volumetric error withouth compensation. The dynamic matching time is adjusted according to servo parameters identified, which leads to 80% decrease of contour error. The application research of thermal dirft compensation system for Simense NC system is introduced. Thermal drift error compensation system is verified stability by experiments. Synthetic error compensation technologies are applied in heavy-duty milling and boring machine tool. The machining error is decreased dramaticly for a total reduction of 35% after compensation.
Keywords: floor-typed milling and boring machine tool, synthetic error modeling,
measurement in multi-station, thermal deformation of ram, error compensation
- IV -
目录
目 录
摘 要 ......................................................................................................................... I Abstract ..................................................................................................................... III 第1章 绪 论 .......................................................................................................... 1 1.1 课题背景及研究目的和意义 ......................................................................... 1 1.2 机床误差补偿技术的研究现状 ..................................................................... 2
1.2.1 误差测量技术 .......................................................................................... 3 1.2.2 误差预测模型相关方面研究 ................................................................. 11 1.2.3 误差测量不确定性 ................................................................................ 13 1.2.4 伺服误差补偿技术 ................................................................................ 14 1.3 数控落地铣镗床的误差测量和补偿技术存在的主要问题 ....................... 15 1.4 本文的主要研究内容 ................................................................................... 16 第2章 重型数控落地铣镗床的综合误差分析与建模 ........................................ 17 2.1 引言 ............................................................................................................... 17 2.2 重型数控落地铣镗床的误差溯源分析 ....................................................... 17
2.2.1 重型数控落地铣镗床的结构 ................................................................ 17 2.2.2 重型数控落地铣镗床的加工误差分析 ................................................ 18 2.2.3 重型数控落地铣镗床的几何误差 ........................................................ 19 2.2.4 重型数控落地铣镗床的热误差分析 .................................................... 21 2.2.5 重型数控落地铣镗床的动态伺服误差 ................................................ 23 2.2.6 重型数控落地铣镗床的反向间隙误差 ................................................ 25 2.3 综合空间误差模型 ....................................................................................... 26 2.3.1 坐标系的设定 ........................................................................................ 26 2.3.2 误差耦合 ................................................................................................ 27 2.3.3 几何误差敏感系数矩阵 ........................................................................ 30 2.4 本章小结 ....................................................................................................... 32 第3章 大尺寸空间误差测量不确定度分析及分区测量技术 ............................ 33 3.1 引言 ............................................................................................................... 33 3.2 重型数控落地铣镗床空间误差测量的不确定度 ....................................... 33 3.2.1 空间误差测量的不确定度溯源 ............................................................ 33 3.2.2 激光跟踪仪测量不确定度 .................................................................... 34 3.2.3 重型数控落地铣镗床不确定性因素分析 ............................................ 37 3.3 基于Monte Carlo法的测量不确定度评定 ................................................. 39 3.3.1 不确定度评定的结构 ............................................................................ 40
- V -
哈尔滨工业大学工学博士学位论文
3.3.2 空间误差检测过程的温升标定 ............................................................ 41 3.3.3 空间点位置测量不确定度的验证 ........................................................ 42 3.4 激光跟踪仪测量站位优化 ........................................................................... 43 3.4.1 激光跟踪仪的布站 ................................................................................ 44 3.4.2 激光跟踪仪的站位优化 ........................................................................ 45 3.4.3 单因素优化分析 .................................................................................... 46 3.5 重型数控落地铣镗床空间误差分区测量 ................................................... 47 3.5.1 激光跟踪仪分区测量的空间坐标转换 ................................................ 48 3.5.2 坐标变换参数求解精度的仿真分析 .................................................... 50 3.6 空间误差的分区实例 ................................................................................... 53 3.6.1 大尺寸空间的分区 ................................................................................ 53 3.6.2 坐标变换 ................................................................................................ 53 3.7 本章小结 ....................................................................................................... 54 第4章 重型数控落地铣镗床几何误差辨识 ........................................................ 55 4.1 引言 ............................................................................................................... 55 4.2 误差敏感性分析 ........................................................................................... 55 4.2.1 几何误差敏感系数 ................................................................................ 55 4.2.2 单项误差敏感性分析 ............................................................................ 56 4.2.3 空间尺寸参数对几何误差敏感性影响的分析 .................................... 59 4.3 几何误差辨识 ............................................................................................... 64 4.3.1 垂直度误差检测 .................................................................................... 64 4.3.2 基于直线运动的位移几何误差辨识 .................................................... 66 4.3.3 W轴转角几何误差辨识 ......................................................................... 67 4.3.4 Z轴角度几何误差辨识 .......................................................................... 67 4.3.5 基于粒子群优化算法的X轴和Y轴的转角几何误差辨识 ............... 68 4.4 误差测量及辨识的验证与分析 ................................................................... 72 4.4.1 几何误差辨识验证 ................................................................................ 72 4.4.2 误差分区测量的实验验证 .................................................................... 74 4.4.3 几何误差拟合精度分析 ........................................................................ 75 4.5 本章小结 ....................................................................................................... 78 第5章 重型数控落地铣镗床动态伺服参数辨识 ................................................ 79 5.1 引言 ............................................................................................................... 79 5.2 机床伺服误差建模 ....................................................................................... 79 5.2.1 机床动态综合轨迹误差 ........................................................................ 79 5.2.2 机床动态空间误差模型 ........................................................................ 81 5.3 基于顺逆圆轨迹误差的伺服误差解耦 ....................................................... 84
- VI -