纳米金刚石与石墨烯在切削液中的应用研究

优良切削液的使用能够改善工件的表面质量,同时也能够降低刀具磨损。从纳米金刚石的"滚珠轴承效应"和石墨烯的高导热性上入手,通过在切削液中两种添加剂不同浓度的配制进行不同加工方法加工工件的实验,得出了表面粗糙度以及刀具磨损度的不同结果。实验结果表明:加入两种纳米添加剂进切削液,其最佳配比方案能够提高工件表面质量30%以上,同时能提高刀具寿命达60%以上,从而可大幅降低成本,提高经济效益。     

纳米硬质合金刀具切削Al/SiCp复合材料实验

SiC颗粒具有较高的硬度,使Al/SiCp复合材料在切削时刀具磨损剧烈。纳米硬质合金具有较高的硬度、韧性及良好的抗磨损能力。制备了纳米硬质合金刀具WC-7Co,对Al/SiCp复合材料进行了切削实验,研究了纳米硬质合金刀具磨损机理和Al/SiCp复合材料的切屑去除机理,以及刀尖处后刀面磨损值。研究认为,纳米硬质合金刀具磨损的机理为SiC颗粒的微切削作用引起的磨料磨损,及SiC颗粒对刀尖刃口的高频、断续冲击引起的微崩刃及微破损,Al/SiCp复合材料的切削实质是断续切削;Al/SiCp复合材料去除机理为切屑的崩碎去除;纳米硬质合金后刀面磨损值较普通硬质合金小30%~50%。     

金属切削中如何选择切削液

概述了切削液的种类和性能,介绍了目前切削液的使用情况,重点探讨了在不同的材料、不同的切削方法、各种常见刀具及良好的经济效益下选择切削液的基本原则.     

Computational fluid analysis of abrasive waterjet cutting head

Waterjet cutting is an appealing technology for cutting thick materials with zones that must not be affected by heat. This paper presents computational fluid dynamics (CFD) and theoretical analyses to optimize the mixing of components by the multi-phase approach. Water, air, and abrasives are mixed in a mixing chamber. This modeling is used to predict the influence of air and abrasives on the mixing at different distances within the mixing tube. At the same time, particle tracking was conducted to monitor the erosion rate density at the nozzle wall. Results show that nozzle length has an effect on the mixing of water, air, and the abrasives, and that the velocity of the waterjet influences the erosion rate at the nozzle wall. The k-ɛ turbulence model was used for simulation of the abrasive coupled with air. This investigation reveals that the erosion in the nozzle body is higher at the initial zone and that as the length of the nozzle length increases, the volume fraction of air increases accordingly. The entrance of the orifice is affected by a highly pressurized water stream (with minimal particulate matter), which causes chipping at the leading edge. To reduce the turbulence inside the mixing chamber, the use of a vacuum assist could be helpful, but precautions should be taken in order that the abrasives do not escape from the mixing chamber.     

气辅式多射流纳米颗粒高效静电雾化喷射

研究了一种带辅助气体的新型纳米颗粒多射流高效雾化喷射技术。开发了带有辅助气流的多喷嘴静电雾化喷头,引导辅助气体均匀分布于各喷嘴四周形成稳定鞘层气流,从而对带电雾化射流产生拉伸与约束作用,而形成的鞘层气流降低了表面电荷密度,克服了带电喷嘴间的电场干扰,实现了多雾化射流的稳定、持续喷射。研究了静电雾化多射流的喷射、沉积行为,分析了辅助气体供气压强对射流喷射临界启动电压和纳米颗粒均匀性的影响规律。实验结果显示:辅助鞘层气流降低了射流喷射临界启动电压和雾化颗粒直径,提升了雾化纳米颗粒的均匀性。辅助气体供气压强从0kPa增加到50kPa时,雾化多射流喷射临界启动电压从4.9kV降低至2.8kV,纳米颗粒平均直径从845.267nm下降至528.06nm。结果表明:鞘层气流的引入为纳米颗粒的多射流、快速喷射提供了一种有效的技术手段,有助于推动静电雾化技术的应用发展。     

乳化型深孔切削液的切削试验与分析

对切削液的类型和功能进行阐述,比较几种切削液的功能和切削特点,根据内排屑深孔加工的特点和对切削液的要求,选择几种乳化型切削液进行钻削试验。通过对比试验及结果分析,确定出能适应深孔钻削加工的乳化型切削液,可以满足深孔钻削加工中对刀具的冷却润滑和排屑效果,从而可以减少对切削油的使用,降低生产成本及对环境的污染。     

纳米硬质合金刀具切削Al/SiC_p复合材料的实验

针对SiC颗粒硬度高,切削Al/SiCp复合材料时刀具磨损剧烈,本文提出用具有较高硬度、韧性及良好抗磨损能力的WC-7Co制备纳米硬质合金刀具,并对Al/SiCp复合材料进行了切削实验。研究了纳米硬质合金刀具磨损机理和Al/SiCp复合材料的切屑去除机理,以及刀尖处后刀面磨损值。研究认为,纳米硬质合金刀具磨损的机理为SiC颗粒的微切削作用引起的磨料磨损,及SiC颗粒对刀尖刃口的高频、断续冲击引起的微崩刃及微破损;Al/SiCp复合材料的切削实质是断续切削;去除机理为切屑的崩碎去除;纳米硬质合金后刀面磨损值较普通硬质合金小30%～50%。实验表明,纳米硬质合金较普通硬质合金更适于加工Al/SiCp复合材料。     

Experimental analysis of the correlation between cutting force variation and nose wear in cutting operations

The maximum tool service life was investigated using mathematical relations concerning the controlling factors. A mathematical form was established to relate the incremental force to the applied force and the maximum depth of nose wear. The effects of various operating factors were experimentally investigated and the accuracy and precision of the equipment used was established.     

硬车削滚动轴承套圈的试验研究

针对滚动轴承套圈硬车削加工过程中表面质量存在的问题,对硬车削过程中切削用量和刀具参数对表面粗糙度的影响进行了研究,采用CBN刀具进行了6205滚动轴承套圈的硬车削加工试验,将进给量、切削速度、切削深度和刀尖圆弧半径作为试验因子,通过正交试验分析了它们对零件加工后表面粗糙度的影响规律,并归纳出了该试验范围内的最佳切削用量和刀具参数组合。研究结果表明,进给量对表面粗糙度的影响最大,刀尖圆弧半径对表面粗糙度的影响次之,切削速度对表面粗糙度的有一定影响,切削深度对表面粗糙度的影响非常小。     

Experimental modal analysis and vibration monitoring of cutting tool support structure

The objective of this research is to determine how a cutting tool vibrates when chatter occurs and how this motion is related to the acoustic emission signal. Modal analysis impact tests were conducted to obtain the actual natural frequencies and mode shapes of the Cutting Tool Support Structure (CTSS) system. Cutting tests were also conducted to determine the phase relationship between feed and cutting direction accelerations. Acoustic emission tests were performed to determine the relation between AE signals and two accelerations. Bursts of AE signal were observed to occur approximately at the direction turning points of the Lissajous loop.     

微量油膜附水滴切削试验研究

论述微量油膜附水滴(Oil on Water,OoW)加工液发生原理和冷却润滑特点.针对该切削液的冷却润滑特点进行车削试验研究,并在同干切削和乳化液冷却润滑加工方式对比研究的基础上,通过对切削力、平均摩擦因数和切屑形态的研究分析,揭示出微量油膜附水滴具有良好的冷却润滑效果.     

基于LCA切削液的综合选择方法研究

环境、资源、人口是当今社会面临的三大主要问题。依靠科技进步,实现节资增效,减少废物排放,在制造业实施绿色制造已势在必行。在机械制造中,使用不具有环境协调性的切削液是造成环境负荷增加的主要原因之一。根据绿色产品的LCA过程特点,探讨了切削液选择的一般原则。利用层次分析法,结合切削液的功能性要求,成本性要求以及环境性要求建立了切削液的多目标决策体系,在模糊一致矩阵的基础上提出了切削液的优化选择方法,并运用实例进行了论证。     

A turbulent friction and heat transfer study of dispersed fluids with ultra-micronized metallic particles

Turbulent friction and heat transfer behaviors of dispersed fluids with ultra-micronized metallic particles are experimentally investigated in a circular pipe. Viscosity measurements are also conducted by using a viscometer. Aqueous mixtures with γ-Al₂O₃ and TiO₂ particles of which the mean diameters are 13 and 27 nm, respectively, are used to represent the dispersed fluids. The ranges of Reynolds and Prandtl numbers tested are 10⁴～10⁵ and 5.6～10.7, respectively. The relative viscosity of the dispersed fluid with γ-Al₂O₃ particles is about two hundred at the 10% volume concentration, while that of the dispersed fluid with TiO₂ particles is about twenty at the same volume concentration. Both of the relative viscosities are the unexpected results compared with predictions from classical theory of suspension rheology. Darcy friction factors for the comparatively dilute dispersion fluids used in present study coincide well with Kays correlation for tubulent flow of a single phase fluid, which implies that additional pumping power is not required despite adding solid particles into water. The Nusselt number of both the dispersed fluids for fully developed turbulent flow increases with increasing the volume concentration as well as the Reynolds number as expected. At the maximum volume concentration of 3% approximately, the percentage heat transfer enhancement due to addition of particles for the γ-Al₂O₃ and TiO₂ dispersing fluid systems are 60% and 30%, respectively. Under the range of volume concentration in the present study, the new correlation for turbulent convective heat transfer for both of the dispersed fluids is given by the following equation: Nu=0.021Re^0.8Pr.^0.5     

切削液腐蚀金属工件表面的机理探讨

在原子水平上分析了切削液与金属表面反应的速率,认为静电感应电位是腐蚀产生的关键因素,并在实验室观察了铁合金表面的腐蚀现象,发现当钻头与工件表面存在静电电位差(约20V)时容易在工件表面形成微米级腐蚀斑点。采用能量色散X射线光谱仪(Energy Dispersive X-Ray Spectroscopy,EDX)对腐蚀斑点化学成分的分析表明,氧、硫和氯元素是导致腐蚀发生的主要原因。     

金属切削过程中切削热和切削温度场的仿真分析

切削热的产生和由它导致的切削温度是影响金属切削状态的重要物理因素之一。笔者通过45#圆钢在几种不同切削速度下的温度场的仿真分析,直观的表现出切削速度对金属切削热的影响,从而对优化切削参数和研究刀具磨损机理提供方法依据。     

输送粘性或带有悬浮颗粒液体离心泵的选型

着重介绍了离心泵在实际工程应用中，用于输送粘性或带有悬浮颗粒液体时泵的选型方法，主要包括确定其过流部件的材质、结构形式及泵的性能换算关系。     

用水蒸气作冷却润滑剂的切削试验研究

研制水蒸气发生器 ,并用水蒸气作为冷却润滑剂进行切削试验时发现 ,切削力可比干切减少 10 %左右 ,比用乳化液减少 6%左右 ,并初步分析水蒸气作冷却润滑剂的作用机理     

改善不锈钢切削加工性的试验研究

这里推导出阶梯法耐用度试验的数据处理公式，并利用此方法对普通奥氏体不锈钢和加硒不锈钢材料进行了切削加工对比试验，证明了加硒不锈钢的切削加工性比普通奥氏体不锈钢提高了1．5倍。     

基于两级神经网络分析的切削力与切削功率的研究

基于多层神经网络原理,建立了切削深度、进给量和刀具耐用度为输入,以切削速度为输出的第一级神经网络.构造了切削深度和进给量和切削速度为输入,切削力与切削功率为输出的第二级神经网络.获得满足刀具耐用度条件下的切削速度、切削力和切削功率的插值计算模型建立方法.摆脱了传统经验公式的拟合计算的缺陷.为实现系统在线监测分析提供条件.