CNC32数控车床的设计

阐述了数控车床设计方案，包括其设计原理、传动系统、主参数和动力参数、支承件结构形式、主传动系统、进给系统、尾座、润滑、数控系统、防护等，介绍了其主要结构，包括主要支承件的结构、床身导轨的结构、主轴箱的结构、进给系统的结构等。     

Prolinyl Phosphoramidates of Nucleotides with Increased Reactivity

Nucleoside monophosphates (NMPs) are the subunits of RNA. They are incorporated into growing complementary strands when sequences are copied in enzyme-free reactions using organic leaving groups at the phosphates. Amino acids are rarely considered as leaving groups, but proline can act as a leaving group when N-linked to NMPs, so that prolinyl NMPs hydrolyze in aqueous buffer at 37 °C, with half-life times as short as 2.4 h, and they act as monomers in enzyme-free primer extension. Still, their level of reactivity is insufficient for practical purposes, requiring months for some extensions. Herein we report the synthesis of eight substituted prolinyl AMPs together with seven related compounds and the results of a study of their reactivity. A δ-carboxy prolinyl NMP was found to be converted with a half-life time of just 11 min in magnesium-free buffer, and a δ-isopropyl prolinyl NMP was shown to react sevenfold faster than its prolinyl counterpart in enzyme-free genetic copying of RNA. Our results indicate that both anchimeric and steric effects can be employed to increase the reactivity of aminoacidyl nucleotides, i.e. compounds that combine two fundamental classes of biomolecules in one functional entity.     

火箭大喷管数控仿形铣槽控制系统

提出利用大型薄壁曲面的外形面作为基面进行计算机控制的数字化补偿的铣槽加工方案,为此设计出一种独特的仿形仪;给出了系统控制原理和参考偏移量的计算公式。     

超精密车床激光测量误差补偿系统的研制

详细分析了激光测量系统测量误差产生的原因,并提出了补偿测量误差的方法,进而建立了ＨＣＭ－Ｉ型超精密车床激光测量误差补偿系统。系统分辨率为０．０１μｍ。     

数控车床两轴联动系统空间误差建模技术

利用齐次变换对数控车床两轴联动系统的几何误差进行了系统分析,根据小溜板坐标系的不同建立方法分两种情况分析了整个建模过程,论述了两轴间的正交误差对空间误差的影响,建立了两轴联动系统空间误差的数学模型,并利用该数学模型计算出某台数控车床两轴联动系统的空间误差.该分析方法可应用到其他机器设备空间误差的建模中.     

普通车床常见故障的分析与排除

分析了造成普通车床常见故障的原因,总结了故障排除和检修的主要方法,对普通车床及其相关机床的使用、维护和检修具有一定的借鉴和参考价值。     

KSJM6130数控车床实体拆装及仿真实验平台研究

主要介绍KSJM6130数控车床的实体和仿真拆装过程和实现原理,开发出满足本科生教学实验需求的能够满足虚拟环境下进行数控车床仿真拆装和结构认识的实验教学平台,机械部分拆装和仿真为最终实验平台实现整体的机械、电气软硬件一体化仿真实验平台的研制打下坚实基础。     

Copying of RNA Sequences without Pre‐Activation

Template‐directed incorporation of nucleotides at the terminus of a growing complementary strand is the basis of replication. For RNA, this process can occur in the absence of enzymes, if the ribonucleotides are first converted to an active species with a leaving group. Thus far, the activation required a separate chemical step, complicating prebiotically plausible scenarios. Here we show that a combination of a carbodiimide and an organocatalyst induces near‐quantitative incorporation of any of the four ribonucleotides. Upon in situ activation, adenosine monophosphate was found to also form oligomers in aqueous solution. So, both de novo strand formation and sequence‐specific copying can occur without an artificial synthetic step.     

某重型车床横向进给系统传动刚度分析与实验研究

进给伺服系统的性能对数控机床的跟踪及定位精度、加工表面质量等有着重要的作用。针对某重型车床的横向进给系统,综合考虑了轴的扭转刚度、齿轮的啮合刚度、丝杠螺母副接触刚度和丝杠支承轴承的轴向刚度等因素,建立了等效单自由度力学模型,分析刚度因素对工作台输出行为的影响。通过仿真计算分析了中间传动链各个刚度环节对工作台综合刚度的贡献量,找出了传动链的刚度薄弱环节。现场实验测试了工作台不同进给位置下的临界爬行速度,得到了临界爬行速度与丝杠的轴向刚度的关系,理论分析与实验结果相吻合。所得结论为该重型车床横向进给系统的优化设计提供了理论支持。     

就车式汽车制动盘车床进给系统的改进设计

本文以某进口就车式汽车制动盘车床的结构进行了分析,提出了改进设计方案,使其更易制造、装配.