深低温自动化样本库滚子链传动精度研究

Research on the Transmission Accuracy of Roller Chains in Automated Sample Storage at Ultra-Low Temperatures

摘要

样本载板和冻存架体在高度方向上的安全距离小于3mm，要求存取机构的运动精度达到±1mm。-80℃环境下，滚子链在竖直驱动工况下，定位误差主要由节距收缩耦合误差、多边形效应误差、配合间隙误差、垂度误差组成。链条收缩与链轮收缩同向叠加，共同造成系统性定位偏差。垂度误差，在竖直工况下为确定性系统误差。通过结构优化、逻辑优化、误差补偿、闭环反馈、充分润滑等措施可有效提升滚子链定位精度。通过三坐标测量仪实测验证了热收缩理论：45#钢线膨胀系数实测值与理论值偏差<1%。

Abstract

The safety distance between the sample carrier and the cryopreservation rack in the vertical direction is less than 3mm, requiring the motion accuracy of the access mechanism to reach ±1mm. Under -80°C conditions, the positioning error of the roller chain under vertical drive conditions is primarily composed of pitch shrinkage coupling error, polygon effect error, fit clearance error, and sag error. Chain shrinkage and sprocket shrinkage add up in the same direction, collectively causing systematic positioning deviation. Sag error is a deterministic systematic error under vertical conditions. Structural optimization, logical optimization, error compensation, closed-loop feedback, and adequate lubrication can effectively improve the positioning accuracy of the roller chain. Thermal shrinkage theory was experimentally verified using a coordinate measuring machine: the measured value of the linear expansion coefficient of 45# steel deviates from the theoretical value by less than 1%.

关键词

深低温 / 节距收缩 / 线膨胀系数 / 垂度误差 / 多边形效应

Key words

deep low temperature / pitch contraction / coefficient of linear expansion / sag error / polygonal effect

参考文献

[1] 国际标准化组织. ISO 606:2013 滚子链和链轮[S]. 日内瓦: ISO, 2013.

[2] 陈立锋, 李朝阳, 王鹏. 输送链传动动力学特性及精度影响因素分析[J]. 机械工程学报, 2020, 56(7): 123-132.

[3] 王鹏, 陈立锋. 基于公差分析的链传动精度设计方法[J]. 机械设计, 2019, 36(5): 45-50.

[4] 李刚, 张勇, 刘军. 低温环境下齿轮传动精度影响因素及优化措施[J]. 机械设计与制造, 2021(3): 234-237.

[5] IWIS Chain Systems. Precision Roller Chain for High-Precision Transmission[M]. 慕尼黑: IWIS Verlag, 2017.

[6] 马庆芳、 方荣生、项立成、离舜 实用热物理性质手册, 1986(2),215-230.