高精度接触式测头测量力恒定设计方法研究

当测微仪采用接触式测头测量工件尺寸时,测量力的变化会对测量误差的修正造成一定影响,这种影响在大量程高精度测量中更为严重。为了减小这种影响,提高测量结果的精确度,利用弹簧弹力同磁铁磁力之间的动态力平衡原理设计一种恒力结构,并进行理论计算。对计算结果的分析与研究表明,利用该设计方法实现测量力恒定是可行的。     

Cost-efficient drilling using industrial robots with high-bandwidth force feedback

Here we present a method for high-precision drilling using an industrial robot with high-bandwidth force feedback, which is used for building up pressure to clamp-up an end-effector to the work-piece surface prior to drilling. The focus is to eliminate the sliding movement (skating) of the end-effector during the clamp-up of the end-effector to the work-piece surface, an undesired effect that is due to the comparatively low mechanical stiffness of typical serial industrial robots. This compliance also makes the robot deflect due to the cutting forces, resulting in poor hole position accuracy and to some extent in poor hole quality. Recently, functionality for high-bandwidth force control has found its way into industrial robot control systems. This could potentially open up the possibility for robotic drilling systems with improved performance, using only standard systems without excessive extra hardware and calibration techniques. Instead of automation with expensive fixtures and precise machinery, our approach was to make use of standard low-cost robot equipment in combination with sensor feedback. The resulting sliding suppression control results in greatly improved hole positioning and quality. The conceptual idea behind the force control is useful also in many other robotic applications requiring external sensor feedback control.     

采用PTI000铂电阻的高精度温度测量系统设计

该文介绍基于三线制恒流源驱动电路并采用Ptl000铂电阻的温度测量系统设计,重点论述了测量原理和方法、电路设计、定标与实测结果。     

数组实现高精度计算的方法研究

讲解了使用C语言中的数组来实现高精度数值计算的方法,可实现任意位超高精度实数的运算。给出了加、减、乘、除基本运算的详细算法,讨论了建立超高精度计算系统的可能性其方法。     

一种高精度基准电压源的设计制作

对能引起电源的时间漂移及电源噪声的诸多因素进行了分析,采用了AD581集成三端器件和uA741运算放大器设计了恒温控制电路,并制作了恒温槽,设计制作高精度基准电压源。该基准源被应用于HHSV-1型高压高稳定性直流电源的基准电压,极大的提高了该直流电源的精度,使其高压高稳定性直流电源在输出电压为10000V,负载电流在2mA的工作情况下,输出电压和电流的稳定度、时漂、温漂均达到10—6量级,波纹系数达10—7。该电压源可以用作粒子加速器,质谱计,CT机等高精度医疗仪器的基准源。     

I-F变换电路的误差分析

通过采用建立等效模型的方法,对I-F变换电路中可能带来误差的环节进行定性分析和定量计算.减小I/V变换电路部分的误差应选择输入失调电压小,且输出电流满足要求的运放.集成运放部分的误差造成因素则包括开环增益和输入阻抗、开环增益和输出阻抗,其他因素包含积分电路和门限装置.     

高精度偏心斜孔的多轴数控加工方法

在分析产品图纸的基础上,比较了高精度偏心斜孔的各种常用加工方法的优缺点,选定五轴数控加工中心作为加工设备,介绍了其加工工艺方法和程序的编制。实际运行结果显示,采用此方法能满足偏心斜孔的精度要求,降低了生产成本,提高了生产效率。     

High-precision machining by measurement and compensation of motion error

This paper describes a systematic method to model and compensate geometric errors of machine tools. In order to separate geometric errors from other errors, measured errors are analyzed in the frequency domain by using the Fourier series. Then, the frequency components corresponding to geometric errors are selected based on the repeatability of their wavelength. Finally, the components are reconstructed and forwarded for the compensation by a fine motion drive. A CNC machine tool with a fine motion mechanism on the Z-axis was developed to compensate the error components in the Z direction on the XY plane. A flat surface machining with non-rotational cutting tools was tested to validate our approach. On the plane of 45 mm×70 mm, the fluctuation of the relative displacement was reduced from 1.3 to 0.5 μm P-V. Machining experiments with a single-crystal diamond tool were also carried out and the straightness of the profile curve was reduced from 1.0 to 0.4 μm. The result of the experiments showed that the geometric errors were compensated separately from the vibration due to the bending mode of the machine column.     

转动刚体上固结悬臂梁系统的高精度数值计算方法

基于转动刚体上固结悬臂梁系统 ,利用 Jordain变分原理建立了系统的动力学方程 ,进而在引入混合变量的基础上 ,将该动力学方程引入哈密尔顿体系 ,并建立了一套高精度时程积分方法。该计算方法对动力学系统的计算不仅有很高的精度 ,而且是绝对稳定的。数值算例说明了该方法的有效性。该方法为动力系统 ,特别是柔性多体系统的深入研究提供了有效的计算途径     

High-precision molding simulation prediction of glass lens profile for a new lanthanide optical glass

Precision glass lens molding (PGLM) is a recently developed method for fabricating glass optical components with high precision in large volumes. Lanthanum optical glasses are extensively used as optical materials owing to their superior optical properties, such as high refractive index, low dispersion, and high transparency. However, the transformation temperature of currently available high refractive index glass is generally above 650 °C and poses a challenge in manufacturing ultra-hard molds, durable coatings, and high-temperature molding equipment using PGLM. In this study, a preparation method for obtaining high refractive index, low -melting -point lanthanide optical glass (B-ZLaT198) used in PGLM was developed to reduce the transformation temperature. The developed method also characterizes the glass refractive indices and thermal-mechanical properties. To achieve the high-precision prediction of a molding shape in a simulation, a viscoelastic constitutive model of glass was established based on a micro-deformation uniaxial compression creep test. Moreover, by solving the Tool-Narayanasway-Moynihan model parameters based on the specific heat capacity fitting of optical glass at different heating and cooling rates, the input parameters of the structural relaxation model (SRM) for simulation prediction of aspheric glass lens profile deviation in the annealing stage were obtained. Finally, the profile deviation of the aspheric lens was predicted using a finite element model simulation. The results showed that the simulation’s predicted profile of an aspheric lens using the SRM model was in good agreement with that of experimental molding profile. In addition, using the SRM provided a higher prediction accuracy than that of the thermal expansion model in the annealing stage. Adopting the SRM was necessary for the annealing simulations of molding pressing and also verified the accuracy of the proposed viscoelastic characterization method for calculating the thermomechanical parameters of optical glasses.