• CN:11-2187/TH
  • ISSN:0577-6686

›› 2001, Vol. 37 ›› Issue (11): 58-61,7.

• 论文 • 上一篇    下一篇

多轴数控机床几何误差的软件补偿技术

张虎;周云飞;唐小琦;陈吉红;师汉民   

  1. 华中科技大学国家数控系统工程技术研究中心
  • 发布日期:2001-11-15

SOFTWARE COMPENSATION TECHNIQUE OF THE VOLUMETRIC ERRORS OF CNC MACHINING CENTERS

Zhang Hu;Zhou Yunfei;Tang Xiaoqi;Chen Jihong;Shi Hanmin   

  1. Huazhong University of Science and Technology
  • Published:2001-11-15

摘要: 论述了在“华中Ⅰ型”数控系统中开发的数控机床几何误差的软件补偿技术。分析了个轴的误差元通过运动链传播的建模问题和其对切削刀具在机床工作空间中的姿态误差的影响;建立了机床结构的每个误差元和切削刀具相对工件位置误差相联系的通用数学模型;采用激光干涉仪直接测量的方法来获取误差模型中各个误差元参数,提出了一种测量机床运动部件滚摆角的新方法;测量点的误差参数被存储在计算机内,在测量点之间采用线性插值来获得补偿点的误差参数。数控系统每8ms中断一次,读取与补偿点相关的位移和转动误差参数以及刀具的参数,利用误差模型计算刀具相对工件的误差在各个运动轴上的误差分量,该误差分量被数控系统叠加到各运动轴的指令位移上,使各个运动轴产生附加的运动,从而实现数控机床几何误差的软件补偿。对比试验表明该补偿技术能使数控机床的几何误差减小70%。

关键词: 几何误差, 数控机床, 误差模型, 误差软件补偿

Abstract: The software compensation technique of a multiaxis machine’s volumetric errors based on the Huazhong I type computer numerically controlled system is developed. The problem of modeling the propagation of errors of individual axes through the kinematic chain, and their effect on the position and orientation errors of the cutting tool in the machine’s work space are analyzed. A general mathematical model, which relates the error in the position of the cutting tip with respect of the machine tool structure, is established. In the volumetric error model the values of the individual error components affecting the machining accuracy are obtained by direct measurement with a laser interferometer, especially a new measurement method of the angular motion errors in roll is proposed. The error terms of the measuring points are stored in tables. Linear interpolation between points is carried out and error functions combined to obtain corrections. The CNC reads the values of the translation and rotation error terms corresponding to axis positions every 8 ms. With the aid of the full volumetric error model, including tool length and orientation, the CNC computes the resulting workpiece to tooltip errors in every motion axis. The correction for these errors is added to the nominal axis position controlled by CNC codes, and then the error compensation is obtained. Experimental results demonstrate that about 70% reduction of the machine’s volumetric errors is gained after compensation.

Key words: CNC machine tools, Error model, Geometric error, Software-based error compensation

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