微量润滑切削加工性能影响因素的研究

介绍了微量润滑（MQL）切削加工技术相对于传统湿式和干式切削的应用优势及应用现状,重点分析了MQL油雾供给与混合系统、润滑油、压缩空气、工件材料、刀具以及切削参数等因素对MQL切削加工性能的影响规律,发现在加工条件确定的情况下,润滑油用量、压缩空气压力和切削参数之间存在最优组合。因此,为了充分发挥MQL切削加工技术的应用优势,必须对MQL工艺系统进行全面而精确的优化。     

低温微量润滑切削304不锈钢的实验研究

低温MQL切削是低温冷风与微量润滑（MQL）相结合的一种绿色环保加工技术。采用改造的YT15刀具对304不锈钢进行低温MQL切削实验,并比较干切削、湿切削、低温MQL切削三种方式对工件的表面粗糙度以及切屑形态的影响。结果表明,低温MQL采用高压低温冷风冷却润滑,高压冷风可直接将润滑油带入刀-屑和刀-工件接触区域,起到更好的润滑作用,有效降低切削区的温度;相对干切削和湿切削,低温MQL切削能明显降低表面粗糙度,改善其断屑性能,获得较好的切屑形态。     

不同MQL安置方式对高速精密车削的影响研究

为比较不同的MQL安置方式对高速精密车削加工的影响,使用德国某公司的超精密机床SB-CNC对轴承钢GCr15分别进行干式、切削液外置供给式MQL以及切削液内置供给式MQL切削试验。通过Kistler加速度传感器和压电式力传感器分别对车刀在加工过程中的径向振动信号和刀尖的三向切削力信号进行采集,并对采集到的信号做时域和频域分析。结果显示,两种MQL润滑方式都对减小切削力和加工中的低频颤振有所抑制,其中,内置式MQL在抑制颤振方面比外置式MQL更有优势,二者在减小切削力能力方面则未见明显区别。     

基于毛细管理论的MQL理论模型及应用

MQL切削加工技术是一项新型的绿色环保加工技术,使用极微量的切削液可以取得良好的加工效果,从而达到保护环境、降低成本的目的.分析了MQL切削加工中切削液的作用原理,基于毛细管理论建立了MQL的理论模型,并进行了MQL精密车削试验,为进一步丰富和发展MQL切削技术奠定了坚实基础.     

高速车削中低温最小量润滑方式的冷却润滑性能

基于复合制冷技术研制一种低温最小量润滑供给装置,分析低温最小量润滑切削的冷却润滑作用,通过干切削、常温冷风、最小量润滑(Minimum quantity lubrication,MQL)、低温冷风、低温最小量润滑(低温MQL)5种冷却润滑条件下高速车削钛合金的切削温度、切削力对比试验,研究低温MQL在高速车削中的冷却润滑性能。结果表明,5种冷却润滑条件中,低温MQL能够最有效降低切削温度,且随着切削速度的提高,其降低切削温度的效果更明显;低温MQL优异的冷却效果有益于微量润滑油润滑作用的发挥,使其对切削区的润滑效果优于MQL,有效地降低高速车削钛合金时的切削力,改善刀具前刀面摩擦状况。     

MQL外圆车削数值模拟及流场分析

基于流体力学理论及流体分析软件FLUENT建立了最小量润滑(MQL)外圆车削模型,模拟了MQL喷雾射流过程,分析了车削后刀面楔形区的流体压强及静压力的分布特性,分析了MQL喷雾形态,结果表明:MQL压缩空气较强的气压和较高的流速对楔形区的流场有很大的影响;楔形区的流场特性对MQL切削液雾滴的运动和渗透有着较大的影响,楔形区的负压差能够促进切削液喷雾的运动,切削液雾滴粒径在集中在(1~20)μm之间,并按一定的规律分布。这对MQL切削参数及雾滴回收装置的研究有一定的参考意义。     

微量润滑技术在切削加工中的应用

微量润滑(MQL)技术作为一种绿色可持续加工技术,在汽车制造、航空航天、模具制造等方面越来越受到人们的关注。介绍了传统MQL以及新型MQL(外冷复合喷雾(EOoW)、内冷复合喷雾(IOoW)和低温冷风复合喷雾(CAOoW)等)的相关原理及常见设备;MQL应用技术的关键性问题:喷雾场、油雾粒度、润滑油种类以及喷嘴位置研究情况;典型难加工材料:钛合金、复合材料、不锈钢以及铸铁MQL技术切削加工应用研究情况;MQL技术未来的研究目标。     

MQL切削技术的综合评价

最小量润滑(MQL)切削技术主要考虑资源消耗和环境影响问题,兼顾质量、技术、经济因素,实现企业效益和社会效益协调优化.通过对MQL功能目标体系的分解及模糊评价的计算表明:与传统湿切削和完全干切削相比,MQL技术综合效益最优.     

最小量润滑在振动钻削中的应用

为了有效地发挥最小量润滑(Minimum quantity lubrication,MQL)在钻削加工中的冷却和润滑性能,把MQL和振动钻削技术结合起来,对MQL在钻削加工(尤其是振动钻削)中的作用效果进行理论分析和试验研究,并对加工中的最大轴向力和表面粗糙度进行测量.研究结果表明,与普通钻削相比,振动钻削能够有效改善MQL的作用效果,通过合理选择参数,能使最大轴向力明显减小,表面粗糙度显著改善;增大振幅是提高MQL作用效果的有效途径,能够降低表面粗糙度,提高加工质量.     

低温最小量润滑供给装置及其性能测试

低温最小量润滑(Cryogenic minimum quantity lubrication,低温MQL)是将低温压缩空气(通常为-10-30℃)与微量润滑油混合雾化后,喷射至加工区,对加工区实施冷却和润滑的一种准干式绿色切削技术。研制高性能低温MQL供给装置是研究和应用该项技术的前提。本文在分析低温MQL供给装置研制现状的基础上,提出采用以复合制冷方法研制一种低温MQL供给装置,并用热电偶和三维粒子动态分析仪对其制冷性能和喷雾性能分别进行了测试,为其在低温MQL切削研究中的应用奠定了基础。     

Evaluation of machinability and economic performance in cryogenic-assisted hard turning of α-β titanium: a step towards sustainable manufacturing

Abstract

Titanium, a difficult-to-cut material, consumes higher time and cost in removing material by machining to produce parts. Machining of Ti alloys has got serious attention owing to its reactive nature with tool materials at elevated temperature that aggravates tool wear. Reportedly, effective and efficient cooling and lubrication at the tool–work interface can ameliorate the machinability of Ti-alloys. In this perspective, this article interrogates the underlying mechanism of critical responses such as surface roughness, temperature, tool life and machining cost under dry, minimum quantity lubrication (MQL) and cryogenic liquid nitrogen (LN2) modes. The effect of cutting speeds and feed rates on such responses have been considered as a function of cooling strategy to standardize the cooling technique as the best alternative for machining. Cryogenic cooling seems to be preponderant regarding machining cost, temperature, surface roughness and tool life in hard turning of a–b titanium alloy. The feasibility of cryogenic cooling was investigated using the iso-response technique in comparison with dry and MQL-assisted hard turning. Experimental results revealed longer tool life and lower machining cost under cryogenic condition followed by MQL and dry machining. Moreover, cryogenic LN2 has been identified as an appropriate alternative to reduce the temperature and surface roughness. On contrary, dry turning evoked a high-temperature and rapid tool wear. In a nutshell, cryogenic assisted hard turning has acceded as a sustainable strategy from an environmental and economic perspective.     

Micro-drilling of Ti–6Al–4V alloy: The effects of cooling/lubricating

This paper presents a series of experimental investigations of the effects of various machining conditions [dry, flooded, minimum quantity lubrication (MQL), and cryogenic] and cutting parameters (cutting speed and feed rate) on thrust force, torque, tool wear, burr formation, and surface roughness in micro-drilling of Ti–6Al–4V alloy. A set of uncoated carbide twist drills with a diameter of 700 μm were used for making holes in the workpiece material. Both machining conditions and cutting parameters were found to influence the thrust force and torque. The thrust force and torque are higher in cryogenic cooling. It was found that the MQL condition produced the highest engagement torque amplitude in comparison to the other coolant–lubrication conditions. The maximum average torque value was obtained in the dry drilling process. There was no substantial effect of various coolant–lubrication conditions on burr height. However, it was observed that the burr height was at a minimum level in cryogenic drilling. Increasing feed rate and decreasing spindle speed increased the entry and exit burr height. The minimum surface roughness values were obtained in the flood cooling condition. In the dry drilling process, increased cutting speed resulted in reduced hardness on the subsurface of the drilled hole. This indicates that the surface and subsurface of the drilled hole were subject to softening in the dry micro-drilling process. The softening at the subsurface of drilled holes under different cooling and lubrication conditions is much smaller compared to the dry micro-drilling process.     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

绿色切削加工技术分析

21世纪的制造业实施绿色制造已势在必行，绿色切削加工技术的研究应运而生。干切削技术避免了切削液的副作用，但它对刀具提出更高的要求；切削液最少量润滑技术能够使切削工作处在最佳状态下，切削液的使用量达到最少，但绿色切削液需深入研究。笔者认为，实现绿色切削加工的关键技术是：1）开发刀具技术。包括新型刀具材料和刀具涂层技术的研究和应用，优化刀具形状及结构；2）开发绿色切削液技术，包括切削液的绿色设计与绿色使用，开发切实可行的废液处理新工艺。     

Performance and evaluation of MoS2 based machining using PVD-TiAlN coated tool

A recent trend on turning of difficult-to-machine (DTM) materials using environmentally friendly vegetable oil has became popular due to its immense machinability aids. Conventional cutting oils fail to give cooling/lubrication at higher cutting speed-feed combination and create environmental pollution. The present work investigated the effect of molybdenum disulphide nanoparticle (nMoS2) dispersed in castor oil, as a cutting fluid, sprayed using minimum quantity lubrication (MQL) technique on turning of AISI O1 cold worked tool steel. The machining was carried out by varying the speed ranging from 110–170 m/min, a feed rate of 0.02-0.08 mm/rev and depth of cut of 0.7 mm. PVD-TiAlN coated tungsten carbide insert was used for the experimentation. The experimental results of nMQL condition were compared with the dry and wet condition. The results proved that application nMQL has given 15–49 % enhanced tool life with better surface finish as compared with dry and wet condition, respectively. No major phase change occurs in nMQL when compared with other conditions because of their low cutting temperature.

     

Deformation behaviour of sintered silicon–copper steel preforms of various aspect ratios during cold upsetting

This paper presents the optimization of the face milling process of 7075 aluminum alloy by using the gray relational analysis for both cooling techniques of conventional cooling and minimum quantity lubrication (MQL), considering the performance characteristics such as surface roughness and material removal rate. Experiments were performed under different cutting conditions, such as spindle speed, feed rate, cooling technique, and cutting tool material. The cutting fluid in MQL machining was supplied to the interface of work piece and cutting tool as pulverize. An orthogonal array was used for the experimental design. Optimum machining parameters were determined by the gray relational grade obtained from the gray relational analysis.     

Effect of cryogenic high-speed milling of compacted graphite iron using indirect spray system

Compacted graphite iron (CGI) is replacing conventional cast iron (CI), especially in the automotive industries for the manufacture of a high-performance and light-weight diesel engine due to its outstanding mechanical properties as compared to the conventional CI. Nevertheless, the pace of replacement is still slow because of the low machining performance encountered by the industries during high-speed machining of CGI. Thus, in this study, the effect of various cooling-lubrication strategies in high-speed machining of CGI using uncoated carbide inserts was investigated. Results showed that the combination of indirect cryogenic cooling and minimum quantity lubrication (MQL) improves the tool life by 26% compared to conventional flood coolant strategy. The result has been clarified by monitoring the cutting force and the sound pressure for each cooling/lubrication strategy.     

Cryogenic minimum quantity lubrication machining: from mechanism to application

Cutting fluid plays a cooling–lubrication role in the cutting of metal materials. However, the substantial usage of cutting fluid in traditional flood machining seriously pollutes the environment and threatens the health of workers. Environmental machining technologies, such as dry cutting, minimum quantity lubrication (MQL), and cryogenic cooling technology, have been used as substitute for flood machining. However, the insufficient cooling capacity of MQL with normal-temperature compressed gas and the lack of lubricating performance of cryogenic cooling technology limit their industrial application. The technical bottleneck of mechanical–thermal damage of difficult-to-cut materials in aerospace and other fields can be solved by combining cryogenic medium and MQL. The latest progress of cryogenic minimum quantity lubrication (CMQL) technology is reviewed in this paper, and the key scientific issues in the research achievements of CMQL are clarified. First, the application forms and process characteristics of CMQL devices in turning, milling, and grinding are systematically summarized from traditional settings to innovative design. Second, the cooling–lubrication mechanism of CMQL and its influence mechanism on material hardness, cutting force, tool wear, and workpiece surface quality in cutting are extensively revealed. The effects of CMQL are systematically analyzed based on its mechanism and application form. Results show that the application effect of CMQL is better than that of cryogenic technology or MQL alone. Finally, the prospect, which provides basis and support for engineering application and development of CMQL technology, is introduced considering the limitations of CMQL.