Construction of an error map of rotary axes on a five-axis machining center by static R-test

This paper proposes an efficient and automated scheme to calibrate error motions of rotary axes on a five-axis machining center by using the R-test. During a five-axis measurement cycle, the R-test probing system measures the three-dimensional displacement of a sphere attached to the spindle in relative to the machine table. Location errors, defined in ISO 230-7, of rotary axes are the most fundamental error factors in the five-axis kinematics. A larger class of error motions can be modeled as geometric errors that vary depending on the angular position of a rotary axis. The objective of this paper is to present an algorithm to identify not only location errors, but also such position-dependent geometric errors, or “error map,” of rotary axes. Its experimental demonstration is presented.     

一种非接触式R-test测量仪球心坐标计算方法

R-test测量仪是用于五轴数控机床转动轴结构误差测量的专用设备,其通过测量球相对测量坐标系的位置变化进行误差辨识。在测量坐标系中,测量球球心坐标计算的准确性和稳定性是保证测量精度的重要前提。为进行测量球球心坐标的精确计算,构建了非接触式R-test测量仪的结构模型并建立了球心坐标计算方程组。以球心坐标计算方程组为基础,简化得到用于球心坐标求解的非线性方程组并构建其目标函数,然后采用差分进化算法提高球心坐标求解的精度。最后,在GF Mikron UCP800五轴机床上进行对比实验,将测量球球心坐标的计算结果与机床实际坐标进行对比,验证所提出球心坐标计算方法的精度和可靠性。     

一种R-test球头球心检测装置结构优化设计方法

基于数控系统绕刀具中心旋转(Rotation tool center point,RTCP)功能,R-test装置被用于多轴联动数控机床的联动精度检测与标定。该仪器通过三个直线位移传感器测量安装于主轴的球头球心空间位置,从而可测量机床多轴联动时的刀具中心点位置误差。在分析测量原理的基础上,提出最大测量空间和测量敏感度的两个用于评价测量性能的指标及相应的数值算法,得到一种R-test装置结构优化设计方法。在选择通用球头芯棒与长度计的情况下,通过约束分析得到测量杆安装圆直径、测量杆与基准面夹角两个关键尺寸的设计区间,利用蒙特卡罗法搜索得到这两个关键尺寸的最优解,完成结构优化设计。仿真表明,优化设计得到的R-test测量装置具有最佳的测量敏感度,可测区域大于半径为4 mm的球体,能满足实际测量精度和测量空间需要。     

非接触式R-test测量仪结构参数优化方法研究

R-test测量仪是用于五轴数控机床旋转轴结构误差测量的专用设备,其结构形式和参数决定了测量范围和可靠性。对采用电涡流位移传感器的非接触式R-test测量仪典型结构及其测量原理进行了分析。在其他元器件尺寸确定的情况下,通过优化计算R-test测量仪结构参数,包括传感器仰角α和传感器中心间距λ,实现测量仪的灵敏度和测量空间最大化,有效改善了测量仪性能。     

油淬火—回火弹簧钢丝市场预测

我国汽车市场的高速发展带动了油淬火—回火弹簧钢丝的生产与销售。通过分析,发现汽车产量x与油淬火—回火弹簧钢丝消费量y之间存在线性关系。建立一元回归模型,采用最小二乘法,回归出y=-18.656 9+0.095 968x,并对此线性关系进行R检验、t检验及F检验,检验结果表明二者线性关系明显、合理,模型整体可靠性较高。根据一元回归模型及汽车增速,预测未来5年油淬火—回火钢丝的消费量。     

Influence of linear-axis error motions on simultaneous three-axis controlled motion accuracy defined in ISO 10791-6

Five-axis machine tools, which combine three linear axes and two rotary axes, are required for accuracy in machining complex shapes. In this paper, to clarify the influence of simultaneous three-axis control motion measurements as specified in ISO 10791-6, the measured results using a ball bar and R-test are compared. As the motion trajectories of the linear axes are not identical in both measurement devices, it is expected that the error motions of the linear axes cause different measurement results depending on the measurement devices. Thus, the squareness errors between the linear axes and the error motions of the linear axes are assumed as error factors that influence the measured results in this study. A mathematical model of a five-axis control machine tool that considers the error motions and squareness errors of the linear axis is constructed, and the influence of those error factors on motion accuracy is examined using an experiment and a simulation. As a result, the squareness errors and error motions of the linear axis are observed to greatly affect simultaneous three-axis controlled motion accuracy.