刀具半径补偿在数控铣削加工中的应用

用同一程序、同一尺寸的刀具,利用刀具半径补偿值,可进行粗、精加工。利用刀具半径的输入值具有小数点后2～4位(0.01～0.0001)的精度,来控制工件轮廓的尺寸精度。     

基于困油容积的外啮合齿轮泵困油现象的研究

外啮合齿轮泵具有结构简单、质量轻、可靠性强等特点,被广泛用于液压设备中。但由于泵体结构和工作原理导致困油现象,严重影响着齿轮泵的工作效率和稳定性。对齿轮泵的困油现象以及现有的解决方法进行简要阐述,仿真分析了齿轮泵的压力分布情况,详细研究了齿轮泵运转过程中困油容积的变化情况,在此基础上提出一种新方法,以求更好地解决齿轮泵的困油问题。     

数控机床五轴变换系统设计与研究

为实现数控机床五轴联动加工,基于国内蓝天系列数控系统提出了控制系统结构的改进方法。数控系统分为任务层和运动层,五轴变换单元集成在运动层。在对五轴机床进行分类并分析其几何信息的基础上,设计了机床的五轴运动库。以CA摆头机床为例,推导了其正向和反向运动变换。基于改进系统及五轴运动库,设计并分析了机床旋转刀具中心控制和三维半径补偿端铣。改进系统具有较好的可移植性,可在数控加工中直接执行刀具位置和方向指令。     

含二硫键多肽的基质辅助激光解吸电离飞行时间质谱研究

The determination of disulfide bonds becomes an important aspect of obtaining a comprehensive understanding of the chemical structure of a protein. Numerous experimental methods have been developed for the determination of disulfide bonds in proteins. Modern mass spectrometry has developed as an important tool for the analysis of disulfide bond patterns due to its advantages of being simple, rapid and sensitive. The dissociations of the disulfide bonds were detected during the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. These fragment ions were attributed to prompt fragmentation or “in-source decay” rather than “post-source decay”. For the double disulfide bonds, ions of plus sulfur and minus sulfur atoms corresponding to cleavages at different sites within the carbon-sulfur-sulfur-carbon disulfide bonds were also observed.