低温微量润滑加工技术研究进展与应用

综述了低温微量润滑技术的最新进展,阐明了研究成果中的关键科学问题.首先,系统分析了从传统设置到创新设计的低温微量润滑装备在切削中的应用形式和工艺特点.其次,揭示了低温微量润滑的冷却润滑机理及其对切削热力演变和工件表面质量的影响机制.然后,基于低温微量润滑的作用机理和应用形式,系统分析了低温微量润滑在车削、铣削、磨削中针...     

低温微量润滑高速铣削PH13—8Mo刀具磨损试验研究

针对高强度不锈钢材料加工性能差、刀具耐用度低的问题,进行了硬质合金刀具在低温微量润滑条件下高速铣削高强度不锈钢PH13—8Mo的刀具磨损试验,结果表明：WSP45刀片比WXM35适合加工PH13—8Mo,低温微量润滑（cMQL）能有效地抑制刀具磨损,提高刀具耐用度;两种刀具在铣削过程中前、后刀面同时发生磨损,最终因刃口严重崩刃而失效。     

微量润滑复合增效技术及其应用研究进展

微量润滑技术具有切削液用量少、润滑效率高等优点,但在特定工况下仍存在冷却性不足以及润滑不充分等问题.微量润滑复合增效技术,如低温冷风、液态CO2等,综合了良好冷却和润滑优势,可有效解决难加工材料清洁切削加工难题.综述了各类微量润滑复合增效技术原理、关键装置及其工艺应用最新研究进展,详细剖析了各类装置性能及其参数调控特性...     

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。     

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.     

Performance profiling of minimum quantity lubrication in machining

This study develops the analytical understanding of mechanical and environmental effects of minimum quantity lubrication (MQL) in machining and profiles the MQL performance as functions of machining and fluid application parameters. Physics-based predictive models are formulated to quantitatively describe the resulting contact stress and temperature distributions under completely dry, MQL (under boundary lubrication), and flood cooling conditions in cylindrical turning. On that basis, the air quality effects in terms of cutting fluid aerosol emission rate and droplet size distribution have been derived through the modeling of evaporation, runaway aerosol atomization, and dissipation processes. Additionally, the abrasion, adhesion, and diffusion wear mechanisms under time-evolving cutter geometry have been quantitatively evaluated for the development of a tool wear and tool life relationship with the fluid application condition. Experimental measurements of force, temperature, aerosol concentration, and tool flank wear rate in dry, MQL, and fluid cooling cases has also been pursued to calibrate and validate the predictive models. The MQL performance profile is assessed through the sensitive analysis of tool utilization, power consumption, and air quality with respect to MQL application parameters; and it serves as a basis to support the overall optimization of machining process by incorporating both mechanical and environmental considerations.     

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.     

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.     

Experimental Investigation on the Compatibility of Nanoparticles with Vegetable Oils for Nanofluid Minimum Quantity Lubrication Machining

Several health and environmental related issues caused by the application of traditional cutting fluids in machining can be solved by implementing eco-friendly technologies such as minimum quantity lubrication (MQL). Moreover, nanofluid MQL has been proposed to enhance the cooling/lubricating properties of pure MQL and displays significantly good results for machinability. However, the mechanism on compatibility of nanoparticles with cutting fluids has not been explored. In this study, nanoparticles with different hardness and vegetable oils with different viscosity were selected for nanofluids preparation. The end milling experiments were carried out on 7050 material by applying MQL with particularly prepared nanofluids. The cutting force and surface roughness were measured corresponding to the machining performance. The compatibility of hardness of nanoparticles with viscosity of base fluids has been evaluated, and the mechanism has been analyzed by new-designed tribology tests. Results show that canola oil-based diamond nanofluids MQL exhibit the lowest cutting force and natural77 oil-based diamond nanofluids perform the lowest surface roughness with reduction of 10.71 and 14.92%, respectively, compared to dry machining condition. The research is novel and contributes to the machining of such materials at the industry level.     

MQL技术在内排屑深孔钻削加工中的应用

针对传统浇注式内排屑深孔钻削加工方法(BTA或DF)存在着切削液消耗量大、生产成本高、污染环境及危害操作者身体健康等问题,本文提出了将MQL技术(最小润滑技术)应用于内排屑深孔加工的方法(即亚干式深孔加工),并对MQL切削加工中切削液的作用与效果进行了分析。通过亚干式深孔钻削试验,确定出水溶性切削液具有良好的雾化效果,并且加工系统具有良好的冷却及排屑效果。针对刀具磨损较大等问题,提出了采用油液混合雾化以及低温冷风的方法,以提高刀具的润滑性和冷却效果。     

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.     

Theoretical and experimental study of the chatter vibration in wet and MQL machining conditions in turning process

Turning is one of the most commonly used cutting processes for manufacturing components in production engineering. The turning process, in some cases, is accompanied by intense relative movements between tool and workpiece, which is called chatter vibrations. Chatter has been identified as a detrimental problem that adversely impacts surface finish, tool life, process productivity, and dimensional accuracy of the machined part. Cooling/Lubrication in the turning process is normally done for some reasons, including friction and force reduction, temperature decrement, and surface finish improvement. Wet cooling is a traditional cooling/lubrication process that has been used in machining since the past. Besides, a variety of new cooling and lubricating approaches have been developed in recent years, such as the minimum quantity lubrication (MQL), cryogenic cooling, nanolubrication, etc., due to ecological issues. Despite the importance of cooling/lubrication in machining, there is a lack of research on chatter stability in the presence of cutting fluid in cutting processes. In this study, the chatter vibration in turning process for two cooling/lubrication conditions of conventional wet and MQL is investigated. An integrated theoretical model is used to predict both the metal cutting force and the chatter stability lobe diagram (SLD) in turning process. This model involves deriving a math equation for predicting metal cutting force for both wet and MQL conditions using experimental training force data and a Genetic Expression Programming (GEP)-based regression model. Also, the traditional single degree of freedom chatter model is used here for predicting the SLDs. The chatter model is discussed and verified with experimental tests. Then, the experimental results of the tool's acceleration signal, work surface texture, surface roughness, chip shape, and tool wear are presented and compared for wet and MQL conditions. The results of this study show that the cooling/lubrication systems such as wet or MQL have a considerable effect on the SLDs. Also, the predicted results of metal cutting force and SLD for both wet and MQL techniques are in good agreement with the experimental data. Therefore, it is recommended that for each lubrication condition including wet, or MQL, the SLD be determined to achieve higher machinability.     

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.     

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.     

低温冷风纳米粒子微量润滑磨削轴承钢试验研究

低温纳米粒子微量润滑（Nano-CMQL）是将低温冷风技术与纳米粒子润滑油两者有效结合起来的一种高效绿色新型磨削加工润滑方法。采用60目陶瓷结合剂的氧化铝砂轮对GCr15淬硬轴承钢进行磨削试验,比较了常温干式、浇注式、低温冷风微量润滑(CMQL)以及Nano-CMQL四种工况在不同磨削参数下的法向磨削力、比磨削能、磨削温度、工件表面轮廓及粗糙度,结果表明,在基础磨削液中加入粒径为40 nm的MoS2固体颗粒制备出的Nano-CMQL磨削液能够有效地减小磨削加工过程中的法向磨削力并降低磨削温度,尤其在高速、大磨深的磨削参数下,其磨削加工性能更加优良。     

Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.     

MQL加工的微量冷却润滑系统

针对大量浇注式传统切削冷却润滑存在的主要问题，提出并构建了由供液系统、切削液和雾液回收装置所组成的适用于MQL加工的微量切削液冷却润滑系统，并阐述了微量冷却润滑系统对机床、工具系统和刀具兼容性的要求，为制造微量切削液冷却润滑系统和实施MQL加工工艺提供了理论和工程依据。     

Experimental evaluation on the effect of electrostatic minimum quantity lubrication (EMQL) in end milling of stainless steels

The machining of stainless steels is very challenging owing to their high toughness and low thermal conductivity, causing high cutting temperatures and rapid tool wear. Conventionally, metalworking fluids in flood form are used during the process to improve surface quality and tool life; however, their use raises issues including environmental pollution and economic concerns. Therefore, an electrostatic minimal quantity lubrication (EMQL) technology was developed to reduce the consumption of metalworking fluids. EMQL is a near-dry machining technology utilizing the synergetic effects between electrostatic spraying and minimum quantity lubrication (MQL), wherein the lubricant is to apply in a form of fine, uniform and highly penetrable and wettable mist droplets directly to the cutting zone. This study investigates the effect of EMQL in end milling of AISI 304 stainless steel in comparison with dry, wet and MQL machining. The results suggest that EMQL reduces tool wear and cutting force, prolongs tool life considerably and enhances surface finish compared with conventional wet and MQL machining. scanning electron microscopy and Energy-dispersive X-ray spectroscopy analyses show that EMQL considerably reduces adhesive and abrasive wear on the flank face because of the lower friction and heat generation resulting from more efficient entry of the lubricant into the cutting interfaces.     

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。