Table of Content

10 March 2022, Volume 33 Issue 05

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State-of-the-art on MQL Synergistic Technologies and Their Applications

YANG Jianzhang, WANG Chengyong, YUAN Yaohui, YUAN Songmei, WANG Xibin, LIANG Cile, LI Weiqiu

2022, 33(05):  506-528.  DOI: 10.3969/j.issn.1004-132X.2022.05.001

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MQL technology had the advantages of low cutting fluid consumption and high lubrication efficiency. However, there were more problems such as inadequate lubrication and low cooling performance under the specific conditions. MQL synergistic technology, such as cryogenic air or liquid carbon dioxide et.al. which combines the advantages of cooling and lubrication, might effectively solve the machining problems of difficult-to-cut materials. The latest research of principle, key devices and technology applications of various types of MQL synergistic technology were summarized. The performance of various devices and their parameter regulation characteristics were analyzed in details. Combining with the applications and the mechanism of MQL synergistic technology, the machinability in titanium alloy, nickel alloy, stainless steel and other difficult-to-cutting materials were analyzed. In addition, a sustainable analysis of various types of MQL synergistic technology was provided. The purpose is to provide technical support and reference for the engineering applications of clean cutting technologies.

Research Progresses and Applications of CMQL Machining Technology

LIU Mingzheng, LI Changhe, CAO Huajun, ZHANG Song, CHEN YunLIU Bo, ZHANG Naiqing, ZHOU Zongming

2022, 33(05):  529-550.  DOI: 10.3969/j.issn.1004-132X.2022.05.002

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The latest development of CMQL technology was reviewed, and the key scientific problems in the research results were clarified. Firstly, the application forms and technology characteristics of CMQL equipment in cutting processes were systematically analyzed from traditional setting to innovative design. Secondly, the cooling and lubrication mechanism of CMQL and the influence mechanism on cutting thermo-force evolution and workpiece surface quality were revealed. Furthermore, CMQL application performances in turning, milling and grinding for typical difficult-to-machined metals were systematically analyzed based on the action mechanism and application form. The effect of CMQL on restraining thermal-mechanical coupling damage and improving quality was better than that of cryogenic and MQL alone. Finally, the limitations of the technology and the development direction were analyzed, which provides the reference for the engineering applications of CMQL technology.

Chip Formation and Tool Wear in High-speed Cutting of Hardened Steels under Cryogenic Liquid Nitrogen Cooling

WU Shixiong, ZHANG Wenfeng, LIU Guangdong, WANG Chengyong

2022, 33(05):  551-559.  DOI: 10.3969/j.issn.1004-132X.2022.05.003

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In view of the lack of relevant research on chip formation and tool wear mechanism in high-speed cutting of hardened steel under cryogenic liquid nitrogen cooling, a high-speed cutting of hardened steels under liquid nitrogen cooling was studied and compared with dry cutting. The cutting force, cutting temperature, characteristics of chip and tool wear were analyzed, and the mechanism of cooling and lubrication, chip formation and tool wear were discussed. The results show that compared with dry cutting, the cutting temperature of cryogenic liquid nitrogen cooling cutting is reduced by 6.9%-9.9%, and the cutting force is increased by 10.1%-12.8% due to material hardening. Compared with dry cutting, chip serration increases obviously under cryogenic liquid nitrogen cooling, which is related to the larger stress and strain in the first deformation zone and the transition from thermoplastic shear instability to periodic brittle fracture in chip formation. Cryogenic liquid nitrogen reduces cutting heat generation in cutting interfaces, the strong jet of liquid nitrogen blows away the chips, and the strong heat transfer capacity quickly take away the heat in the cut areas. Compared with the dry cutting, cryogenic liquid nitrogen may significantly reduce the adhesive wear, alleviate the tool micro-spalling by cooling and strengthen the tool, and improve the tool life by 28.6%-47.1%. Under cryogenic liquid nitrogen cooling conditions, adhesion is no longer one of the main wear mechanism, abrasive wear and impact wear are the main wear mechanism, and flank flaking and micro collapse blade are the main tool damage forms.

Investigation on Tribological Mechanism of Ionic Liquid on Grinding Interfaces under MQL

WANG Dexiang, ZHAO Qiliang, ZHANG Yu, GAO Teng, JIANG Jingliang, LIU Guoliang, LI Changhe,

2022, 33(05):  560-568，606.  DOI: 10.3969/j.issn.1004-132X.2022.05.004

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The grinding properties of two kinds of ionic liquids serving as grinding fluids were investigated experimentally under MQL, which were 1-butyl-3-methylimidazolium tetrafluoroborate (［BMIM］BF4) and 1-hexyl-3-methylimidazolium tetrafluoroborate (［HMIM］BF4), respectively, with electroplated CBN grinding wheel and with nickel-based alloy GH4169 as workpiece material. And molecular dynamics simulations were adopted to reveal the formation mechanism of the physical adsorption film formed by the ionic liquids on the grain/workpiece interfaces. Further, X-ray photoelectron spectroscopy(XPS) analysis was carried out on the machined surfaces of the workpieces to reveal the formation mechanism of the chemical reaction film on the grain/workpiece interfaces. The results show that the two kinds of ionic liquids above are suitable for serving as grinding fluids under MQL. Compared with dry grinding, the ionic liquids may greatly reduce specific grinding energy and grinding force ratio, and improve the grinding quality of the machined surfaces of the workpiece, as well may greatly reduce grinding temperature up to more than 100 ℃, and avoid grinding burn. The fractured grooves on the grain wear flat areas due to micro-crushing are the transport channels for ionic liquids to enter into the grain/workpiece interfaces. The ionic liquid molecules may absorb in the fractured grooves to form boundary lubrication film, which may reduce the friction forces by decreasing the direct contact areas between the abrasive grains and the workpieces. During MQL grinding processes, the chemical reaction films consisting of fluoride and oxide are formed by the chemical reaction between the two kinds of ionic liquid and the workpieces on the grinding interfaces. 

Effects of Phase States on Clean Cutting Performance and Surface Integrity of NiTi Alloys

YU Jianhang, YAN Pei, FAN Lei, GU Huiqing, JIAO LiQ, IU Tianyang, WANG Xibin

2022, 33(05):  569-576.  DOI: 10.3969/j.issn.1004-132X.2022.05.005

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Aiming at the high-efficiency and high-speed clean machining of NiTi alloys, through clean cutting technologies such as dry cutting, carbon dioxide and liquid nitrogen cryogenic cutting, the cutting experiments of NiTi alloys in different phases were designed and the cutting performance and surface integrity indicators were compared and analyzed, and the influence rules of material phases and cutting parameters on the cutting processes of NiTi alloys were studied. The results show that the cutting force of the martensitic phase is the largest and that of the austenitic phase is the smallest, the former may reach 1.04~3.84 times of the latter; there are four elements Ni, Ti, O and C in the chips, mainly TiO2 and NiCO3 form, the formation of the two compounds changes with the cutting temperature, which in turn causes the chip color to change with the processing parameters; when the feed rate is small, the surface roughness Ra value of the austenitic phase is the largest, and the Ra value of the martensitic phase is the smallest, the former may reach 1.24~1.66 times of the latter; under martensitic phase cutting conditions, when the cutting speed is as 130 m/min, the feed rate is as 0.05 mm/r, and the cutting depth is as 0.2 mm, Ra value reaches the minimum value of 0.73 μm. 

Research on Ice Fixation and Low Damage Machining Technology of Superalloy Honeycomb Cores

JIANG Shaowei, WANG Yongqing, LIU Kuo, WU Xiaohui, YANG Zijian, YANG Yuebing, YU Qingbo, YANG Xiaolong

2022, 33(05):  577-582.  DOI: 10.3969/j.issn.1004-132X.2022.05.006

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Aiming at the machining problems of metal honeycomb core, such as thin-walled porosity, anisotropy, weak in-plane rigidity and low radial strength, a ice fixation and low damage machining method of superalloy honeycomb core was proposed. The principles of metal honeycomb core ice fixation clamping were analyzed, the adaptability and reliability of the machining systems were verified. A single factor test of honeycomb core ice fixation cryogenic cooling machining was carried out, the forming rule of honeycomb core machining defects was expounded. The results show that the clamping and machining methods of ice fixation cryogenic cooling are introduced in the machining of metal honeycomb cores, the cutting heat is reduced and the fixation constraint retention achieves during machining, which may improve the ability of the honeycomb wall to resist deformation . Among the cutting parameters, the feed rate has the greatest influence on the machining quality, and the tearing burr accounts for the highest proportion of the machining defects. The optimal cutting parameters may ensure good machining quality with low damage, low roughness and no deformation, and may achieve high quality and high efficiency machining of difficult-to-machine metal honeycomb cores.

Prediction of Surface Roughness for Cryogenic Milling TC17 Titanium Alloys

LEI Yong, ZHAO Wei, HE Ning, LI Liang

2022, 33(05):  583-588.  DOI: 10.3969/j.issn.1004-132X.2022.05.007

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The cryogenic milling tests of TC17 titanium alloy were carried out to evaluate the machined surface roughness under varying cutting conditions. Firstly, the regression analysis method was used to establish an empirical model of the surface roughness, the effects of jet temperature, feed per tooth, milling speed, and radial cutting width on the surface roughness were investigated. And then a prediction model based on BP neural network of surface roughness was established and compared with the empirical model. The results show that the empirical model depicts a strong correlation(R2=0.92) between surface roughness and parameters. The most influential factor on surface roughness is feed per tooth, followed by the jet temperature, the radial cutting width and the milling speed, respectively. The mean square error between the predicted and the experimental values is as 1.73×10-4 μm2, and the maximum relative error is as 8.81%, and the error variation changes more significantly. For the neural network model, the mean square error between the predicted and the test value is as 3.53×10-5 μm2, the maximum relative error is as 3.64%, and the error changes uniformly. Compared with the empirical model, the neural network model has higher prediction accuracy and generalization ability, and may predict the effects of various parameters on surface roughness better.

Multi-layer and Multi-objective Optimization Model and Applications of Grinding Process Plan for Cleaner Production

LYU Lishu, DENG Zhaohui , LIU Tao, WAN Linlin,

2022, 33(05):  589-599.  DOI: 10.3969/j.issn.1004-132X.2022.05.008

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In order to effectively realize the energy saving and emission reduction of the grinding processes, a multi-layer and multi-objective optimization model of the grinding process plan for cleaner production was proposed. A model of grinding energy consumption and carbon emission was established from the perspective of “three streams (material flow, energy flow and environmental emission flow)” of cleaner production. A multi-layer and multi-objective optimization model targeting grinding energy consumption, grinding carbon emissions and grinding time was established from the routing levels and process parameter levels, and an improved genetic algorithm based on the combination of AHP(analytic hierarchy process) and CRITIC(criteria importance through intercriteria correlation) was proposed for optimization. The grinding processes of a certain bearing ring were tested and verified. Compared with the traditional processing plan, the optimization processing plan obtained through algorithm saves 6.48% machining time, 42.81% energy consumption, and 8.26% carbon emissions at the routing level; and saves 25% grinding time, 18.84% energy consumption and 8.69% carbon emissions at the process parameter level, which verifies the effectiveness of the model and method. Finally, corresponding energy-saving and emission-reduction strategies were proposed based on the above research. 

Design and Experimental Study of Cryogenic Medium Internal Cooling Toolholders

ZHAO Di, WANG Yongqing, LIU Kuo, XING Jiapeng, LIU Haibo

2022, 33(05):  600-606.  DOI: 10.3969/j.issn.1004-132X.2022.05.009

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In order to meet the requirements of cryogenic internal cooling reformation for conventional machine tools, a cryogenic internal cooling toolholder was designed. The idea of double-layer of the toolholder with inner rotation and outer static was proposed. Heat transfer processes and the strength reliability of the toolholder were analyzed and the structures were optimized. The temperature fields, overall deformations and strengths of the toolholder were verified by thermal-fluid-solid coupling simulation. Then, a cryogenic medium internal cooling toolholder was developed, and the geometric accuracy and temperature change were tested. The research results show that the toolholders have good thermal insulation performance and may maintain high geometric accuracy in stable working states, which may meet the requirements of cryogenic internal cooling machining of conventional machine tools, and lays a foundation for further study on ultra-low temperature clean cutting technology.

Study on Oil Mist Control and Oil Mist Particle Characteristics of MQL Systems

LIANG Cile, YUAN Yaohui, WANG Chengyong, LI Weiqiu, YANG Jianzhang, WU Huayi

2022, 33(05):  607-614.  DOI: 10.3969/j.issn.1004-132X.2022.05.010

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MQL oil mist control and mist particle transport mode directly affected the changes of oil mist states, and then affected the spraying particle characteristics to the cutting areas. The oil quantity control performance and regulation rule under the conditions of different MQL atomization parameters and mist particle transport modes were studied based on the built-in MQL atomization technology and the application characteristics of the oil mist internal transmission. The influences of the inner diameter and transmission stroke of the oil mist transmission pipeline on the mist particle characteristics were revealed by combining with the mist particle characteristics at the oil mist outlet of transmission pipeline. The results show that the pressure difference in atomization chamber plays a more significant role in the regulation of the oil mist quantity than that of the intake pressure, and it is necessary to combine the influence of pressure difference and intake pressure to consider the regulation of the oil mist quantity by the number of atomizer opening. In the transmission processes, the size and length of the transmission pipeline are important factors affecting the oil mist particle characteristics. 

Cutting Characteristics of Tools under Dual Lubrication Conditions

YI Mingdong, WANG Jianping, LI Chuanhao, XU Chonghai,

2022, 33(05):  615-622.  DOI: 10.3969/j.issn.1004-132X.2022.05.011

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 To realize the clean cutting technology, a Ti(C,N)-based self-lubricating cermet tool(TMC tool) was prepared by using a vacuum hot-press sintering process and an Al2O3-coated CaF2 composite powder as the additive phase, and the cutting performances of Ti(C,N)-based self-lubricating cermet for cutting 300M steel were investigated under the effect of MQL, the results show that the three-way cutting forces FX、FY、FZ are decreased by 36.8%, 13.1% and 32.2%, respectively, and the cutting temperature decreased by 44.3% for the dual lubrication compared with the dry cutting method. The wear on the flank faces of the tools is significantly improved under the same cutting distance condition, which is beneficial to prolong the tool life and improve the machined surface quality. In addition, energy dispersive spectrum(EDS) analysis results show that the solid lubricating films are formed on the rake faces and flank surfaces of the tools to reduce the friction. Dual lubrication effectiveness is adopted to effectively reduce the adhesive wear and oxidation wear.

Complex Characteristics and Multi-dimensional Control Strategies of Heat Flow in Dry Gear Hobbing Machines

YANG Xiao, ZENG Lingwan, CHEN Peng, DU Yanbin, LI Bo

2022, 33(05):  623-629.  DOI: 10.3969/j.issn.1004-132X.2022.05.012

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Aiming at the thermostability of dry gear hobbing machines, the heat flow characteristics and optimal control strategies were studied. By analyzing the features of drive method and structural layout, the complex and multi-source characteristics were explored for heat flow of dry gear hobbing machines. And further, multi-field coupled model was established for heat storage of dry gear hobbing machine based on macro and micro heat transfer mechanism. Finally, multi-dimensional control strategies were proposed for analyzing influence factor of thermostability. The involved strategies contain the collaborative optimization of thermostability, the field synergy enhancement of compressed air and the multi-sensor data fusion perceived control of the heat flow.