Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has...Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.展开更多
基于临床PICC(Peripherally Inserted Central Catheter)置管手术过程,提出了一套静脉穿刺装置及控制系统设计方案,该装置采用B超图像引导,通过微控制器,达到自动静脉穿刺置管目的。自动静脉穿刺装置采用双步进电机丝杠螺母传动装置,控...基于临床PICC(Peripherally Inserted Central Catheter)置管手术过程,提出了一套静脉穿刺装置及控制系统设计方案,该装置采用B超图像引导,通过微控制器,达到自动静脉穿刺置管目的。自动静脉穿刺装置采用双步进电机丝杠螺母传动装置,控针电机推动穿刺针和软管穿刺皮肤进入血管,置管电机推动软管到位并触发退针按钮,使针体退回针筒内。采用速度和加速度分段控制策略,在整个穿刺过程中设置多个关键控制点,再分别对各行程段进行控制,各段行程和速度根据不同静脉血管的深度和内径情况进行自动预选,从而达到快速精确控制进针和置管的目的。展开更多
文摘Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.
文摘针对某铁路项目现有微台阶法等施工开挖台架机械化水平低,作业效率低等问题,设计出一种适配多种开挖工法的履带式悬挑开挖台架,以满足现场采用微台阶等工法开挖的需求,并能克服走行低效的问题.经实地应用与分析,开挖工序单循环进尺两榀,开挖工序使用本台架较传统平均用时节约0.8 h,单循环进尺三榀较传统平均用时节约0.5 h;立架工序单循环立架两榀,使用本台架立架工序较传统平均用时节约0.4 h,单循环立架三榀较传统台架平均用时节约0.5 h.
文摘基于临床PICC(Peripherally Inserted Central Catheter)置管手术过程,提出了一套静脉穿刺装置及控制系统设计方案,该装置采用B超图像引导,通过微控制器,达到自动静脉穿刺置管目的。自动静脉穿刺装置采用双步进电机丝杠螺母传动装置,控针电机推动穿刺针和软管穿刺皮肤进入血管,置管电机推动软管到位并触发退针按钮,使针体退回针筒内。采用速度和加速度分段控制策略,在整个穿刺过程中设置多个关键控制点,再分别对各行程段进行控制,各段行程和速度根据不同静脉血管的深度和内径情况进行自动预选,从而达到快速精确控制进针和置管的目的。
