粒度对颗粒流滴注润滑车削影响实验

颗粒流滴注润滑是一种新型绿色切削润滑技术,能解决传统颗粒流切削的颗粒导入问题。为了研究颗粒粒度对切削效果的影响,进行45钢车削实验,用不同粒度的Al₂O₃颗粒流润滑,分析切削力、切削温度、光洁度、刀具寿命和粒度的关系。实验结果显示：粒度影响切削效果,存在最佳粒度,粒度过大或过小都会导致切削效果变差;粒度过大会影响颗粒流渗透进摩擦面,粒度过小则无法适应粗糙及剧烈变动的摩擦面,两者都限制了颗粒流的分离和抹平作用,导致减摩效果变差;采用合理粒度,颗粒流点滴润滑切削效果甚至好于浇注润滑。     

颗粒流滴注润滑车削实验研究北大核心

为了解颗粒流滴注润滑的切削加工规律,在干切削、浇注润滑、颗粒流滴注润滑条件下,对45钢进行精、粗车削实验,比较试样的切削力、切削温度和粗糙度的差异,研究颗粒流滴注润滑对切削加工的影响。结果表明:颗粒流滴注润滑径向切削力小于浇注润滑,切向和轴向切削力和浇注润滑相差不大;颗粒流滴注润滑切削温度小于浇注润滑;颗粒流滴注润滑加工表面粗糙度小于浇注润滑。颗粒流滴注润滑可以代替浇注润滑,显著降低润滑液用量,具有环保性。     

高速干切削技术分析

面向环境的绿色工艺设计是实现绿色制造的有效途径，是制造业可持续性发展的重要方向，保证企业的经济效益和社会效益最优化。在切削加工中大量使用切削液进行冷却润滑提高了加工成本并带来环境污染问题，消除这些与使用切削液有关的问题的合理措施是采用高速干切削方式。文章提出了干切削技术的新内涵，分析了高速干切削技术的绿色特征，重点分析了实现高速干切削的机床技术，刀具技术和工艺技术。     

最小量润滑装置的设计与应用

为了符合绿色制造的发展方向,微量润滑技术逐步取代传统浇注式技术,而应用该技术的前提是设计出优良的微量润滑装置。在研究微量润滑技术以及国内常见微量润滑装置的基础上,设计一种新型微量润滑装置,并阐述精密雾化喷嘴、密封式缸体、润滑油循环系统等设计原理,最后通过切削实验与干切削和传统微量润滑装置进行对比。实验结果表明此装置在工业切削领域的可应用性,并且相比传统微量润滑装置有更好的切削效果。     

准干式切削技术的研究进展

针对传统切削加工过程中使用切削液的弊端,分析了准干式切削技术的特点,介绍了微量润滑、低温微量润滑和水蒸气冷却等常见准干式切削技术的原理及其国内外研究现状,指出准干式切削技术具有很好的节能环保、降低加工成本等优点,具有广泛的应用前景。     

准干式切削技术的研究进展

针对传统切削加工过程中使用切削液的弊端,分析了准干式切削技术的特点,介绍了微量润滑、低温微量润滑和水蒸气冷却等常见准干式切削技术的原理及其国内外研究现状,指出准干式切削技术具有很好的节能环保、降低加工成本等优点,具有广泛的应用前景。     

低温冷风微量润滑切削技术发展及应用

介绍了绿色加工技术的分类及特点,阐述了低温微量润滑切削技术的机理,总结了低温冷风微量润滑技术及装置的最新研究成果,分析了低温冷风微量润滑技术存在的问题以及发展方向,为低温冷风微量润滑技术的进一步研究以及工程应用提供参考。     

高压CO2冷却切削高温合金GH4169的切削特性研究

以高压CO₂为冷源和切削液载体的冷却润滑加工技术，能有效改善难加工材料加工质量并具有环保优势，其工艺有待深入开发。结合CO₂热力学状态、流体运动方程以及传热模型，建立了各冷却加工参数之间的联系。基于有限元对高压CO₂冷却切削GH4169的过程进行计算与分析，考察各工艺参数对切削性能的影响。结果表明，相比干切和浇注式切削，CO₂介入后能明显改善切削力、切削温度以及表面残余应力。提高CO₂喷射压力可以降低切削力与温度，喷射角度和喷嘴半径对切削力和温度呈现非单调性变化，在一定范围内存在最佳值。适当增大喷射压力可促进切屑断屑。     

齿轮类零件滚磨光整加工技术现状及发展思考

齿轮类零件是制约我国各类高端装备自主研发的核心基础件,齿轮表面质量对其长寿命、低噪声、高稳定性运行至关重要.在全面分析齿轮类零件多种不同光整加工工艺基础上,从形性协同、一体化普适高效加工的角度,明确了滚磨光整加工工艺改善齿轮类零件表面完整性的优势.在综合概述滚磨光整加工基本特征后,全面系统地综述了国内外有关齿轮类零件滚磨光整加工技术的研究与应用现状,归纳总结了不同工艺的技术原理、特点及适用范围.针对齿轮类零件滚磨光整加工现阶段存在的不同问题,立足优质高效、绿色普适和产业化实用的高质量发展理念,从齿轮结构特征、滚磨光整方式、加工表面演化、复合加工机理、介质基本特征和改性工艺组合等方面,提出了系统的新思考、新策略,对进一步推进齿轮类零件滚磨光整加工技术不断升级发展有积极的参考与借鉴.     

不锈钢纳米流体微量润滑车削实验研究

纳米流体微量润滑(NFMQL)是一种全新的微量润滑(MQL)增效技术,为了解其对不锈钢切削的效果,分别在干切削、浇注润滑、MQL和Al_2O_3颗粒的NFMQL条件下对SUS304不锈钢进行车削,比较切削力、切削温度、光洁度和刀具寿命的差异。实验结果显示:NFMQL冷却润滑效果要好于MQL,但比浇注润滑差;NFMQL比MQL更容易获得较小的切削力和切削温度、光洁度以及更长的刀具工作寿命,NFMQL对光洁度和刀具寿命改善显著。NFMQL改善不锈钢切削性能,适合在不锈钢切削中应用。     

微量润滑赋能雾化与供给系统关键技术研究进展

传统金属切削液会对环保、人体健康及制造成本产生负面影响,难以满足绿色制造的发展需求。微量润滑是一种介于浇注式和干式加工的润滑剂绿色供给技术,利用压缩空气将少量可降解的生物润滑剂雾化,形成微液滴,从而起到润滑和抗磨减摩的作用。然而,尚无相关研究针对雾化微液滴精准输运技术的规律进行总结,无法为微量润滑供给参数提供科学指导。为此,综述了微量润滑赋能雾化和供给系统关键技术的研究进展。揭示了微量润滑两相流气动雾化液滴粒径和雾化锥角随供给参数的演变规律,提出了静电雾化微量润滑赋能供给新方法,分析了静电赋能雾化性能调控机制和荷电流体渗透特性,阐述了超声赋能雾化液滴均一化机理和工艺参数优化策略。进一步分析了基于流体动力学模型的刀具/砂轮–工件界面流场分布规律,阐明了喷嘴结构对液滴输运的影响规律,为喷嘴位姿参数的选取提供了理论支撑。此外,论述了喷嘴位姿参数化调控装置的研究进展,解决了润滑介质参数化供给难题。最后,展望了微量润滑复合增效和智能供给关键技术,以期为微量润滑技术的工程应用提供理论支持和技术指导。     

A Study on Tribology in Minimal Quantity Lubrication Cutting

Despite the fact that minimal quantity lubrication (MQL) machining produces almost similar cutting performance to conventional flood supply machining while using much less metal working fluid (MWF), it has not been fully utilized in industry due to lack of understanding of the fundamental process physics. To take full advantage of MQL machining and expand its applicability, an understanding of its tribological behavior is critical. Hence, in this study, the adsorption characteristics of MQL media during orthogonal cutting was investigated using two experimental setups; one in a high vacuum chamber with a mass spectrometer to observe mass changes of MQL media during cutting, and another setup in an atmospheric chamber where the supply of MQL media can be controlled. The former is mainly for analysis of the tribological behavior of MQL media, and the latter for cutting performance monitoring. It was found that the adsorption amount of MQL media was closely related to lubrication behavior. Oxygen in MQL supply plays a significant role in lubrication. Ultrasonic vibration cutting tests with MQL were conducted for further understanding of lubrication mechanism.     

Micro-texture at the coated tool face for high performance cutting

This paper describes the effect of micro surface texture on the lubrication conditions at the tool rake face in machining aluminum alloy. For this purpose, four types of micro surface texture were fabricated at the tool faces of cemented carbide through spattering, photolithography and wet etching, and the micro-textured tool faces were coated with diamond like carbon (DLC) or TiN. Then, orthogonal cutting experiments of aluminum alloy were conducted using the coated tools with and without micro-texture. The normal and friction forces and the coefficient of friction were obtained from the measured cutting forces. In addition, tool surface conditions were inspected with a CCD microscope after machining. As a result, it was found that parallel type and square-dot type of micro-textures improved effectively the lubrication conditions in machining aluminum alloy A6061-T6. It was also found that micro-texture was likely to improve the lubrication conditions more effectively as the pattern of texture became smaller and deeper.     

内置式MQL喷射特性对车削GCr15轴承钢的影响

微量润滑(MQL,Minimum Quantity Lubrication)加工作为绿色切削技术,其应用逐渐广泛。相对于外置式MQL,内置式MQL具有渗透性好、切屑影响小、效率高等特点。为了寻求出内置式MQL的喷射特性对加工的影响规律,开发了车削内置式MQL系统,设计了四因素三水平的正交实验。以切削力和表面粗糙度为评价指标,切削液流量、空气流量、可生物降解润滑油及切削速度为变量,沿后刀面喷射,进行了车削GCr15轴承钢的正交实验,分析了喷射参数对加工的影响规律,并得到了优化的喷射参数,对机械加工工程应用具有参考意义。     

A comparative study on dry milling and little quantity lubricant milling based on vibration signals

Green manufacturing is the theme of manufacturing industry in the 21st century. In order to realize green manufacturing, it is critical to decrease the usage of cutting fluid in machining as much as possible. Presently, there are still a lot of difficulties in the adoption of dry cutting and MQL cutting for various reasons. This paper presents a new method called little quantity lubrication (LQL) in machining and a comparative study on dry milling and LQL milling based on vibration signals. The vibration signals were acquired from workpiece surface in peripheral milling and were analyzed in time domain, frequency domain and time–frequency domain. The results show that vibration signals can be significantly affected by cutting fluid in milling process. For the sake of reducing vibration and cutting fluid usage, process parameters should be considered while deciding whether or not and how to apply cutting fluid. This research gives a valuable insight in applying LQL in machining.     

Burr formation in short hole drilling with minimum quantity lubrication

Machining with minimum quantity lubrication (MQL) is state of the art. Previous investigations were, however, concerned with tool optimisation and the surface quality of workpieces as well as coating technology. By now the same or partly better machining results than in conventional cutting with flood lubrication can be achieved due to adjusted tool geometries, workpiece materials and coatings. Tests about burr formation in short hole drilling exist for dry cutting or the machining with emulsion. This paper expands these results to the burr formation in machining with MQL.     

Cutting performance of different coatings during minimum quantity lubrication drilling of aluminum silicon B319 cast alloy

Cutting performance of cemented carbide drills with various coatings was investigated in detail under minimum quantity lubrication (MQL) conditions. An advanced dual-channel Bielomatik MQL system was installed in an Okuma machining center. A specially designed Mapal drill was selected for the studies to eliminate voids between the tool and the MQL tool holder that can interfere with mist delivery. Using this design, a mist flow rate of 25 mL/min was achieved through the drills.Progressive frictional/wear studies were performed. Coated drills were tested in three stages (50, 500, and 7000 holes). During short term drilling tests (50-hole level), cutting performance was comprehensively evaluated for a range of coatings by measuring several in-situ frictional characteristics of the cutting process, such as cutting forces, and related characteristics including, chip type and undersurface morphology. Wear patterns of the cutting tools were indentified as well. Selected coatings were tested further. The best cutting performance based on the 500-hole testing was found with the diamond coating. However, excessive brittleness of the entire coating/substrate system led to premature failure of the drill after 4300 holes. The low-hydrogen DLC coating that also showed promising cutting performance based on the 500-hole test was selected as the next candidate for further testing. Drills with low-hydrogen DLC coating achieved 7200 drilled holes with a flank wear of only 110 μm and moderate intensity of workpiece material pickup. This results in a better surface finish of drilled holes.Based on this study, the Mapal drills with the low-hydrogen DLC coating provided comparable machining performance to that possible with traditional wet machining, but with the environmental and cost advantages possible with MQL.     

Flow visualization and characterization for optimized MQL machining of composites

Limited information is available on the effect of Minimum Quantity Lubrication (MQL) parameters (oil flow rate OFR, air flow rate AFR, nozzle orientation and distance from the cutting zone) on flow characteristics. ‘Particle Image Velocimetry’ and ‘Phase Doppler Anemometry’ flow visualization methods were used to define the optimal MQL jet for better penetration and cooling/lubrication; coherent, small magnitude/number of vorticities, and small droplets of high velocity. Effect of flow characteristics on cutting forces, temperature, tool wear and geometric errors was examined in CFRP milling. Optimum AFR, OFR and nozzle distance from the cutting zone were established and compared to flood, pressurized air, and dry machining.     

放电诱导可控烧蚀高效加工典型工艺方法

提出了一种以放电诱导产生可控烧蚀为基础的高效加工方式。利用大部分金属在放电诱导后表面产生活化区会与通入的氧气发生燃烧的特点,通过放电诱导,使加工表面产生活化区,并控制氧气的通入量,使加工表面金属产生可控高效烧蚀,而后通过电火花加工、电解加工、车削、铣削、磨削等工艺方法修整烧蚀表面,完善表面质量与精度。此种加工方法特别适合于钛合金、高温合金、高强度钢等难加工金属材料的加工。由于采用水溶性非可燃工作液,节能环保,不会产生有害气体及燃烧隐患,因此也是一项绿色制造技术,是机械加工领域一种全新的高效加工方法。