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Simulation of abrasive flow machining process for 2D and 3D mixture models

Rupalika DASH,Kalipada MAITY

《机械工程前沿（英文）》 2015年第10卷第4期页码 424-432 doi: 10.1007/s11465-015-0366-6

摘要：

Improvement of surface finish and material removal has been quite a challenge in a finishing operation such as abrasive flow machining (AFM). Factors that affect the surface finish and material removal are media viscosity, extrusion pressure, piston velocity, and particle size in abrasive flow machining process. Performing experiments for all the parameters and accurately obtaining an optimized parameter in a short time are difficult to accomplish because the operation requires a precise finish. Computational fluid dynamics (CFD) simulation was employed to accurately determine optimum parameters. In the current work, a 2D model was designed, and the flow analysis, force calculation, and material removal prediction were performed and compared with the available experimental data. Another 3D model for a swaging die finishing using AFM was simulated at different viscosities of the media to study the effects on the controlling parameters. A CFD simulation was performed by using commercially available ANSYS FLUENT. Two phases were considered for the flow analysis, and multiphase mixture model was taken into account. The fluid was considered to be a Newtonian fluid and the flow laminar with no wall slip.

关键词： abrasive flow machining (AFM) computational fluid dynamics (CFD) modeling mixture model

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Effects of process parameters on surface roughness in abrasive waterjet cutting of aluminium

M. CHITHIRAI PON SELVAN, N. MOHANA SUNDARA RAJU, H. K. SACHIDANANDA

《机械工程前沿（英文）》 2012年第7卷第4期页码 439-444 doi: 10.1007/s11465-012-0337-0

摘要：

Abrasive waterjet cutting is a novel machining process capable of processing wide range of hard-to-cut materials. Surface roughness of machined parts is one of the major machining characteristics that play an important role in determining the quality of engineering components. This paper shows the influence of process parameters on surface roughness (R_a) which is an important cutting performance measure in abrasive waterjet cutting of aluminium. Taguchi’s design of experiments was carried out in order to collect surface roughness values. Experiments were conducted in varying water pressure, nozzle traverse speed, abrasive mass flow rate and standoff distance for cutting aluminium using abrasive waterjet cutting process. The effects of these parameters on surface roughness have been studied based on the experimental results.

关键词： abrasive waterjet aluminium garnet water pressure mass flow rate traverse speed standoff distance

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Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

ZHAO Qingliang, Brinksmeier Ekkard, Riemer Oltmann, Rickens Kai

《机械工程前沿（英文）》 2007年第2卷第3期页码 350-355 doi: 10.1007/s11465-007-0061-3

摘要： In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 yD grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope. The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential of super abrasive diamond wheels in ductile machining brittle materials.

关键词： ELID peripheral electrolytic in-process nickel-electroplated monolayer measurement

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Molecular dynamics modeling of a single diamond abrasive grain in grinding

Angelos P. MARKOPOULOS,Ioannis K. SAVVOPOULOS,Nikolaos E. KARKALOS,Dimitrios E. MANOLAKOS

《机械工程前沿（英文）》 2015年第10卷第2期页码 168-175 doi: 10.1007/s11465-015-0337-y

摘要：

In this paper the nano-metric simulation of grinding of copper with diamond abrasive grains, using the molecular dynamics (MD) method, is considered. An MD model of nano-scale grinding, where a single diamond abrasive grain performs cutting of a copper workpiece, is presented. The Morse potential function is used to simulate the interactions between the atoms involved in the procedure. In the proposed model, the abrasive grain follows a curved path with decreasing depth of cut within the workpiece to simulate the actual material removal process. Three different initial depths of cut, namely 4 ?, 8 ? and 12 ?, are tested, and the influence of the depth of cut on chip formation, cutting forces and workpiece temperatures are thoroughly investigated. The simulation results indicate that with the increase of the initial depth of cut, average cutting forces also increase and therefore the temperatures on the machined surface and within the workpiece increase as well. Furthermore, the effects of the different values of the simulation variables on the chip formation mechanism are studied and discussed. With the appropriate modifications, the proposed model can be used for the simulation of various nano-machining processes and operations, in which continuum mechanics cannot be applied or experimental techniques are subjected to limitations.

关键词： molecular dynamics abrasive process chip formation cutting force temperature

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Depth of cut models for multipass abrasive waterjet cutting of alumina ceramics with nozzle oscillation

Jun WANG

《机械工程前沿（英文）》 2010年第5卷第1期页码 19-32 doi: 10.1007/s11465-009-0082-1

摘要： An experimental study of the depth of cut in multipass abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented. It is found that this cutting technique can significantly increase the depth of cut by an average of 50.8% as compared to single pass cutting without nozzle oscillation under the corresponding cutting conditions and within the same cutting time. Predictive models for the depth of cut are then developed. The modelling process starts with single pass cutting using a dimensional analysis technique and the particle erosion theories applied to alumina ceramics, before progressing to the development of the models for multipass cutting. The models are finally assessed both qualitatively and quantitatively with experimental data. It is shown that the model predictions are in good agreement with the experimental data with the average deviations of about 1%.

关键词： abrasive waterjet engineering ceramics depth of cut cutting performance nozzle oscillation machining

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游离磨料多股线线锯切割实验研究

王金生,姚春燕,彭伟,金鑫, 陈世杰

《中国工程科学》 2012年第14卷第11期页码 94-98

摘要：

游离磨料线锯切割是将磨浆中的磨粒通过一定速度的细钢丝线带入切割区域，达到去除工件材料的目的。多股线由多根细金属线绕制而成，表面具有很多凹槽，与钢丝线光滑表面相比，可以输送更多的磨粒进入切割区域，从而提高切割效率。应用0.25 mm的多股线和0.25 mm的钢丝线对光学玻璃K9进行切割对比实验，结果表明，在相同工艺条件下，多股线的切割效率和表面粗糙度均优于钢丝线，但切缝宽度大于钢丝线。

关键词：线锯游离磨料加工切割效率

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采矿过程中磨料水射流性能通用预测方法

Eugene Averin

《工程（英文）》 2017年第3卷第6期页码 888-891 doi: 10.1016/j.eng.2017.12.004

摘要：

极端采矿条件下的硬岩破碎可采用磨料水射流（AWJ）技术，这种技术能够在不产生粉尘的条件下有效切割难以机械加工的材料。这种技术还可用于爆破、本安和消防安全。就断裂力学而言，每一种可被破坏的材料均可被视为韧性或脆性材料。因此，需要找到一种无论使用AWJ 对何种材料进行切割都能精确预测其效率的方法。该问题可通过能量守恒法加以解决，它显示了材料去除量与AWJ 动能之间的比例。本文介绍了基于能量守恒法的预测方法，并提出如何达到最有效破坏水平的建议，以及关于涉及磨料流量与水流量、靶距和磨料颗粒粒径关系值的合理范围的建议。本文还提供了基于断裂力学的临时结构法确定材料破坏起始阈值条件的参数。

关键词：磨料水射流能量守恒法切割深度断裂力学阈值速度采矿

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Applications of the crystallization process in the pharmaceutical industry

Sohrab ROHANI

《化学科学与工程前沿（英文）》 2010年第4卷第1期页码 2-9 doi: 10.1007/s11705-009-0297-z

摘要： The applications of the crystallization technique in the pharmaceutical industry as a purification and separation process for the isolation and synthesis of pure active pharmaceutical ingredients (API), co-crystals, controlled release pulmonary drug delivery, and separation of chiral isomers are briefly discussed using a few case studies. The effect of process variables and solvent on the polymorphism and morphology of stavudine is discussed. The implementation of external control in the form of feedback and real-time optimal control using cooling and antisolvent crystallization of paracetamol in water-isopropyl alcohol is introduced. Two methods to prepare micron-sized drug particles, namely, micro-crystallization and polymer-coated API-loaded magnetic nanoparticles for pulmonary drug delivery, are discussed. The significance of co-crystals in drug administration is highlighted using the theophylline-nicotinamide co-crystal system. Resolution of chloromandelic acid derivatives, a racemic compound, is achieved using direct crystallization and diastereomeric salts crystallization. The crystal structures of diastereomeric salts of chloromandelic acid and phenylethylamine are determined. The structure comparison between the less soluble and more soluble salts shows that weak interactions such as CH/π interactions and van der Waals forces contribute to chiral recognition when the hydrogen bonding patterns are similar.

关键词： feedback morphology pulmonary paracetamol recognition

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Degradation of refractory organics in concentrated leachate by the Fenton process: Central compositedesign for process optimization

Senem Yazici Guvenc, Gamze Varank

《环境科学与工程前沿（英文）》 2021年第15卷第1期 doi: 10.1007/s11783-020-1294-1

摘要： Abstract • 90% total COD, 95.3% inert COD and 97.2% UV254 were removed. • High R2 values (over 95%) for all responses were obtained with CCD. • Operational cost was calculated to be 0.238 €/g CODremoved for total COD removal. • Fenton oxidation was highly-efficient method for inert COD removal. • BOD5/COD ratio of leachate concentrate raised from 0.04 to 0.4. The primary aim of this study is inert COD removal from leachate nanofiltration concentrate because of its high concentration of resistant organic pollutants. Within this framework, this study focuses on the treatability of leachate nanofiltration concentrate through Fenton oxidation and optimization of process parameters to reach the maximum pollutant removal by using response surface methodology (RSM). Initial pH, Fe2+ concentration, H2O2/Fe2+ molar ratio and oxidation time are selected as the independent variables, whereas total COD, color, inert COD and UV254 removal are selected as the responses. According to the ANOVA results, the R2 values of all responses are found to be over 95%. Under the optimum conditions determined by the model (pH: 3.99, Fe2+: 150 mmol/L, H2O2/Fe2+: 3.27 and oxidation time: 84.8 min), the maximum COD removal efficiency is determined as 91.4% by the model. The color, inert COD and UV254 removal efficiencies are determined to be 99.9%, 97.2% and 99.5%, respectively, by the model, whereas the total COD, color, inert COD and UV254 removal efficiencies are found respectively to be 90%, 96.5%, 95.3% and 97.2%, experimentally under the optimum operating conditions. The Fenton process improves the biodegradability of the leachate NF concentrate, increasing the BOD5/COD ratio from the value of 0.04 to the value of 0.4. The operational cost of the process is calculated to be 0.238 €/g CODremoved. The results indicate that the Fenton oxidation process is an efficient and economical technology in improvement of the biological degradability of leachate nanofiltration concentrate and in removal of resistant organic pollutants.

关键词： Concentrated leachate Fenton oxidation Central composite design Biodegradability Inert COD

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Review on mechanism and process of surface polishing using lasers

Arun KRISHNAN, Fengzhou FANG

《机械工程前沿（英文）》 2019年第14卷第3期页码 299-319 doi: 10.1007/s11465-019-0535-0

摘要： Laser polishing is a technology of smoothening the surface of various materials with highly intense laser beams. When these beams impact on the material surface to be polished, the surface starts to be melted due to the high temperature. The melted material is then relocated from the ‘peaks to valleys’ under the multidirectional action of surface tension. By varying the process parameters such as beam intensity, energy density, spot diameter, and feed rate, different rates of surface roughness can be achieved. High precision polishing of surfaces can be done using laser process. Currently, laser polishing has extended its applications from photonics to molds as well as bio-medical sectors. Conventional polishing techniques have many drawbacks such as less capability of polishing freeform surfaces, environmental pollution, long processing time, and health hazards for the operators. Laser polishing on the other hand eliminates all the mentioned drawbacks and comes as a promising technology that can be relied for smoothening of initial topography of the surfaces irrespective of the complexity of the surface. Majority of the researchers performed laser polishing on materials such as steel, titanium, and its alloys because of its low cost and reliability. This article gives a detailed overview of the laser polishing mechanism by explaining various process parameters briefly to get a better understanding about the entire polishing process. The advantages and applications are also explained clearly to have a good knowledge about the importance of laser polishing in the future.

关键词： laser polishing surface roughness process parameters mechanism

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Tool path strategy and cutting process monitoring in intelligent machining

Ming CHEN, Chengdong WANG, Qinglong AN, Weiwei MING

《机械工程前沿（英文）》 2018年第13卷第2期页码 232-242 doi: 10.1007/s11465-018-0469-y

摘要：

Intelligent machining is a current focus in advanced manufacturing technology, and is characterized by high accuracy and efficiency. A central technology of intelligent machining—the cutting process online monitoring and optimization—is urgently needed for mass production. In this research, the cutting process online monitoring and optimization in jet engine impeller machining, cranio-maxillofacial surgery, and hydraulic servo valve deburring are introduced as examples of intelligent machining. Results show that intelligent tool path optimization and cutting process online monitoring are efficient techniques for improving the efficiency, quality, and reliability of machining.

关键词： intelligent machining tool path strategy process optimization online monitoring

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Seasonal and treatment-process variations in invertebrates in drinking water treatment plants

Zhiling Wu, Xianchun Tang, Hongbin Chen

《环境科学与工程前沿（英文）》 2021年第15卷第4期 doi: 10.1007/s11783-020-1354-6

摘要： Abstract • Seasonal and treatment-process variations in invertebrates in a DWTP were analyzed. • The propagation and leakage of invertebrates in BAC filter were the most serious. • Invertebrates can survive and reproduce in chlorine disinfected clear water tanks. • Proportions of endogenous invertebrates increased along the treatment process. Problems associated with excessive propagation and leakage of invertebrates in drinking water have received increasing attention in recent years. We performed a monthly survey of invertebrate abundance and taxa in the effluent of each treatment stage in a drinking water treatment plant between May 2015 and April 2016 and analyzed seasonal and treatment-process variations in invertebrates. The results showed that invertebrate abundances in raw water, effluent of the biological activated carbon (BAC) filter, and finished water significantly correlated with water temperature, whereas no correlation was observed between water temperature and invertebrate abundance in the effluents of the sedimentation tank and sand filter. The dominant taxa in the effluent of each treatment stage were rotifers, nematodes, and crustaceans. The sedimentation tank could efficiently remove invertebrates with an annual average removal rate of 92%. The propagation and leakage of invertebrates occurred in the sand and BAC filters but more seriously in the latter. The average reproduction rate in the BAC filter was 268.8% with rotifers as the taxon that leaked the most. Invertebrate survival and reproduction were also observed in the chlorine-disinfected clean water reservoir with an average reproduction rate of 41.9%. Owing to differences in chlorine resistance, the reproduction ability of the dominant taxa was in the order nematodes>crustaceans>rotifers. The proportion of endogenous invertebrates gradually increased along the treatment process. The average proportion of endogenous invertebrates in the finished water was higher than 79.0%. Our findings suggested that waterworks should pay more attention to endogenous invertebrate growth.

关键词： Invertebrates Drinking water Seasonal variations Treatment process

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Special issue on “Green chemical process and intensification”

《化学科学与工程前沿（英文）》 2022年第16卷第11期页码 1533-1535 doi: 10.1007/s11705-022-2263-y

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Sulfate digestion process for high purity TiO

T. A. LASHEEN

《化学科学与工程前沿（英文）》 2009年第3卷第2期页码 155-160 doi: 10.1007/s11705-009-0005-z

摘要： A titania slag product of Rosetta ilmenite assaying 72% TiO is treated by the sulfate process option of the pigmentary TiO manufacture. The relevant factors of acid concentration, particle size, slag/acid ratio besides the reaction temperature, and time have been studied. After dissolving the cured mass in dilute acid and clarification, the obtained solution was subjected to hydrolysis of its titanium content. The final product was bleached under reducing conditions to redissolve the residual coloring impurities before being dewatered and calcinated. The obtained results indicated that a leaching efficiency of about 92% was realized due to the presence of some refractory components in the working slag material, namely, rutile and magnesium iron titanate. The obtained white pigment assay attained up to 99.85% TiO , while the analyzed impurities involve 77 ppm Mn and only 14 and 7 ppm of total iron and V, respectively.

关键词： titania slag sulfate process pigment