【作者】 鲁志政；

【导师】 杨建国；

【作者基本信息】 上海交通大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 随着现代机械制造技术的飞速发展,精密和超精密加工技术已经成为现代机械制造的重要组成部分。数控机床作为机械制造中的重要工具,它的精度指标是影响工件加工精度的重要因素。因此,提高数控机床精度的研究受到了极大的关注。数控机床的体积定位精度包括线性位移误差、直线度误差、垂直度误差、角偏和刚性误差,这些误差决定了数控机床的精度性能。机床在工作中产生运动误差难以避免,为了提高机床的加工精度,这就需要对机床的误差检测及补偿做出研究。对于三轴机床(加工中心),在空间直角坐标系中,总共就会产生21项误差,逐一测量这些误差非常费事费时间。因此,如何能够高效精确地检测数控机床的体积定位精度关系到数控机床的补偿性能和精度。通过测量数控机床各项误差并加以补偿,可以很好地改善机床性能,从而大大提高加工精度。本文在数控机床误差的检测以及补偿方面做了以下几个有益的尝试和探索。(1)通过与美国光动公司合作,在结合矢量运算和体对角线多步测量法的基础上,提出激光矢量分步对角线测量方法来测量数控机床的体积误差。该方法具有使用方便和调整快速的特点,可以方便地获得可用于机床空间位置误差补偿的12项机床误差元素,包括3个定位误差、6个直线度误差和3个垂直度误差,从而为误差补偿实施开创了有利条件,并利用补偿软件自动生成补偿代码,最后通过实验验证了该方法的高效辨识性和可靠性。(2)进一步分析了激光矢量分步对角线法的辨识精度和辨识条件,并且发现实际测量中可能遇到因为辨识条件不满足而导致的辨识精度下降的问题。通过合理数学分析、假设、几何图形运算和理论推导,提出了一种新的补充方案。该方案可以在辨识条件不具备的情况下,即激光束与平面镜不垂直的前提下,提高数控机床对直线度误差和垂直度误差的辨识精度。(3)分析热因素在机床误差辨识的过程中的影响,针对铣床做了连续14天的实验数据采集,然后经过数据处理、分析、比对,以及一些合理的数学变换,得到了引起机床热对机床各误差的影响大小和关键点的分步特征,并针对这些因素,采取了改变了铣床的结构,改善冷却液的使用以及冷却液的走向,大大降低了热因素对机床误差的影响,获得了很好的试验效果。最后还针对热误差采用时序法建模,优化模型,通过实施补偿成功的将机床的热误差从补偿前的25.32微米减小到补偿后的8.57微米。更多还原

【Abstract】 Precision and high-precision manufacturing is now becoming important integrity of the mordern manufacturing as the qucik development of technology. The accuracy of numerical controlled machines is the key factor to the precision of manufacturing. CNC machines play more and more important role in today’s work and life. The volumetric errors of CNC machines contain followings, such as linear displacement errors, straightness errors, squareness errors, angle errors and rigid errors. Totally speaking, the CNC machines contain 21 errors due to its complicated structure. How to improve the accuracy of the CNC machines is now becoming the key problems in the world. The best way to improve the accuracy of CNC machines is to identify the errors and complement them with sofeware. The paper makes such useful research and discuss as followings below.(1) The paper introduces a new measurement based on LDDM- Laser step diagonal measurement called the laser vector step-diagonal measurement. It is a new error measurement method which executes a diagonal as a sequence of single-axis motions and combines the vector calculation. It executes a diagonal as a sequence of single-axis motions. It can enable the identification of all the volumetric error components including 3 linear errors, 6 Straightness errors and 3 Squareness errors.(2) The paper also analyzes the accuracy of measurement and proposes a new formulation to accurately identify volumetric errors even under the existence of setup errors. The effectiveness of the proposed modified identification scheme is investigated experimentally by an application example to a high-precision machine tool. (3) The paper also makes some research in the straightness and squareness errors change due to the thermal affects. The development of thermal errors from a cold machine to a temperature stable state may concern in many cases hundreds of micrometers. These facts make it extremely difficult to measure the influence of the thermal affects on the geometric characteristics of a certain machine tool. Reported here is a novel method capable of covering the development of all the machine straightness and squareness errors accompanied with the monitoring of the relevant machine temperatures. At last, the paper sets up the modle to succefully reduce the error from 25.32 micrometers to 8.57 micrometers.更多还原