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Serrated chip characteristics and formation mechanism in high-speed machining of selective laser melted Ti6Al4V alloys

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Science China(Technological Sciences) 2023年第5期66卷 1435-1450页

作者： LIU DeJian WANG YouQiang NI ChenBing ZHU LiDa ZHENG ZhongPeng School of Mechanical and Automotive Engineering Qingdao University of TechnologyQingdao266520China Key Lab of Industrial Fluid Energy Conservation and Pollution Control Ministry of EducationQingdao266520China School of Mechanical Engineering and Automation Northeastern UniversityShenyang110819China School of Mechanical Engineering Tsinghua UniversityBeijing100084China

Serrated chips,consisting of extremely uneven plastic deformation,are a prominent feature of high-speed machining of difficultto-machine *** paper focuses on the evolution of chip form,chip morphology features(chip free surface,tool-chip contact surface,and chip edge),and chip segment parameters in subsequent high-speed(vc=50 and 150 m min-1)machining of selective laser melted(SLMed)Ti6Al4V alloys,which are significantly different from conventional Ti6Al4V alloy in microstructure,mechanical properties and *** effect of laser beam scanning schemes(0°,67.5°,and 90°),machined surfaces(top and front),and cutting speeds on serrated chip characteristics of SLMed Ti6Al4Valloys was *** on the Johnson-Cook constitutive model of SLMed Ti6Al4Valloys,an orthogonal cutting model was developed to better understand the effect of physical-mechanical properties on the shear localization,which dominates the formation mechanism of serrated chips in post-machining of SLMed Ti6Al4V *** results showed that the critical cutting speed(CCS)for chip serration of SLMed Ti6Al4V alloy is lower than that for serrated chips of conventional Ti6Al4V alloy,and the serrated profile of SLMed Ti6Al4V chips was more regular and ***,due to anisotropic microstructure and mechanical properties of SLMed Ti6Al4Valloys,the serration degree of chips produced on the top surfaces of SLMed Ti6Al4Valloys is more prominent than that of chips generated on the front *** addition,because of the poor deformation coordination and high plastic flow stresses of needle-like martensiteα′,the plastic flow and grain distortion in the adiabatic shear band(ASB)of SLMed Ti6Al4V chips are significantly smaller than those in the ASB of conventional Ti6Al4V with equiaxed grains.

关键词： serrated chips selective laser melted Ti6Al4V alloys high-speed machining chip characteristics anisotropic properties

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Atomic-scale dissecting the formation mechanism of gradient nanostructured layer on Mg alloy processed by a novel high-speed machining technique

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Journal of Materials Science & Technology 2021年第23期82卷 227-238页

作者： Hui Fu Xiaoye Zhou Bo Wu Lei Qian Xu-Sheng Yang State Key Laboratory of Ultra-precision machining Technology Advanced Manufacturing Technology Research CentreDepartment of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute ShenzhenChina Guangdong Province Key Laboratory of Durability for Marine Civil Engineering School of Civil EngineeringShenzhen UniversityShenzhen 518060China

Severe plastic deformation(SPD)-induced gradient nanostructured(GNS)metallic materials exhibit superior mechanical performance,especially the high strength and good *** this study,a novel high-speed machining SPD technique,namely single point diamond turning(SPDT),was developed to produce effectively the GNS layer on the hexagonal close-packed(HCP)structural Mg *** high-resolution transmission electron microscopy observations and atomistic molecular dynamics simulations were mainly performed to atomic-scale dissect the grain refinement process and corresponding plastic deformation mechanisms of the GNS *** was found that the grain refinement process for the formation of the GNS Mg alloy layer consists of elongated coarse grains,lamellar fine grains with deformation-induced-tension twins and contraction twins,ultrafine grains,and nanograins with the grain size of~70 nm along the direction from the inner matrix to ***,experiment results and atomistic simulations reveal that these deformation twins are formed by gliding twinning partial dislocations that are dissociated from the lattice dislocations piled up at grain *** corresponding deformation mechanisms were evidenced to transit from the deformation twinning to dislocation slip when the grain size was below 2.45μ***,the Hall-Petch relationship plot and the surface equivalent stress along the gradient direction estimated by finite element analysis for the SPDT process were incorporated to quantitatively elucidate the transition of defo rmation mechanisms during the grain refinement *** findings have implications for the development of the facile SPD technique to construct high strength-ductility heterogeneous GNS metals,especially for the HCP metals.

关键词： Gradient nanostructured Mg alloy high-speed machining Deformation twinning high-resolution transition electron microscopy Hall-Petch relationship

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Adaptation of feed rate for 3-axis CNC high-speed machining

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Journal of Harbin Institute of Technology(New Series) 2009年第3期16卷 391-395页

作者：张得礼周来水 College of Mechanical and Electrical Engineering Nanjing University of Aeronautic and Astronautic

To improve the efficiency of CNC machining, assumptive transit circular arc is used to contour two adjacent moves together on the comer to make smooth paths. The radios of transit circular arc can be adjusted with contour accuracy, and the feed rate on the corner can be controlled through limiting the maximum feed rate of transit circular arc segment. A look-ahead algorithm for a series of moves is proposed for speed adjustment in advance, which avoids the occurrence of overload of cutting tool on the comer and reduces the servo track error of parts on the corner or of circular arc move. Equivalent trapezoidal velocity profile is used to analyze the speed of S-curve velocity profile and work out its accurate interpolation, which overcomes the disadvantage of looking up table to calculate feed rate approximately, hence high accuracy and fine surface quality can be obtained while the machining speed is high. The proposed methods can meet the requirements of real-time analysis of high-speed machining. The presented algorithm is effective and has been adopted by CNC system of newly developed high-speed milling machine.

关键词： CNC feedrate smoothing S-curve velocity profile high-speed machining

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Development of high-speed machining Database with Case-based Reasoning

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厦门大学学报（自然科学版） 2002年第S1期41卷 48-49页

作者： WANG Zun-tong, LIU Zhan-qiang, AI Xing (School of Mechanical Engineering, Shandong University, Jinan 250061, China)

Applying high-speed machining technology in shop floor has many benefits, such as manufacturing more accurate parts with better surface finishes. The selection of the appropriate machining parameters plays a very important role in the implementation of high-speed machining technology. The case-based reasoning is used in the developing of high-speed machining database to overcome the shortage of available high-speed cutting parameters in machining data handbooks and shop floors. The high-speed machining database developed in this paper includes two main components: the machining database and the case-base. The machining database stores the cutting parameters, cutting tool data, work pieces and their materials data, and other relative data, while the case-base stores mainly the successfully solved cases that are problems of work pieces and their machining. The case description and case retrieval methods are described to establish the case-based reasoning high-speed machining database. With the case retrieval method, some succeeded cases similar to the new machining problem can be retrieved from the case-base. The solution of the most matched case is evaluated and modified, and then it is regarded as the proposed solution to the new machining problem. After verification, the problem and its solution are packed up into a new case, and are stored in the case-base for future applications.

关键词： case-based reasoning high-speed machining database case

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Tool-path planning for free-form surface high-speed high-resolution machining using torus cutter

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Journal of Harbin Institute of Technology(New Series) 2006年第3期13卷 337-342页

作者：王宇晗李儒琼吴祖育陈兆能 School of Mechanical and Dynamical Engineering Shanghai Jiaotong University Shanghai 200030 China

In CNC machining, two essential components decide the accuracy and machining time for a sculptured surface: one is the step-size interval, the other is the tool-path interval. Due to the limitation of the conventional method for calculating the tool-path interval, it cannot satisfy the machining requirement for high-speed and high-resolution machining. Accordingly, for high-speed and high-resolution machining, the current study proposes a new tool-path interval algorithm, plus a variable step-size algorithm for NURBS. Furthermore, a new type cutter, which can improve the cutting efficiency, is investigated in the paper. The transversal equation of the torus cutter onto the flat plan is given in this paper. The tool-path interval is calculated with the transversal equation and the proposed algorithm. The illustrated example shows that the redundant tool paths can be reduced because an accurate tool-path interval could be calculated.

关键词： high-speed machining tool-path planning free-form surface torus cutter

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Failure mode change and material damage with varied machining speeds:a review

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International Journal of Extreme Manufacturing 2023年第2期5卷 36-60页

作者： Jianqiu Zhang Binbin He Bi Zhang Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China

high-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band(ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM.

关键词： high-speed machining adiabatic shear band subsurface damage dynamic recrystallization

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Chatter stability and precision during high-speed ultrasonic vibration cutting of a thin-walled titanium cylinder

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Chinese Journal of Aeronautics 2020年第12期33卷 3535-3549页

作者： Zhenlong PENG Deyuan ZHANG Xiangyu ZHANG School of Mechanical Engineering and Automation Beihang UniversityBeijing 100083China Institute of Bionic and Micro-Nano Systems Beihang UniversityBeijing 100083China Beijing Advanced Innovation Center for Biomedical Engineering Beihang UniversityBeijing 100083China

Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical ***,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ***,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low ***,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy *** this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of ***,the kinematics,tool path,and dynamic cutting thickness of HUVC are ***,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness *** can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the ***,comparison experiments are conducted between HUVC and CC *** results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting *** addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC.

关键词： high-speed machining Minimum chip thickness Mode-coupling Thin-walled cylinder Ultrasonic vibration cutting

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Intelligent NURBS Interpolator Based on the Adaptive Feedrate Control

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Chinese Journal of Aeronautics 2007年第5期20卷 469-474页

作者：张得礼周来水南京航空航天大学机电学院CAD/CAM工程研究中心南京210016

To satisfy the need for high-speed and high-accuracy machining of NURBS curve. Firstly the form of NURBS curve is analyzed and Talor＇s expansion of the parameter u with respect to time t is used to obtain the algorithm of the first order approximation interpolation. Secondly, based on the algorithm of the controlled chord error interpolator, an intelligent interpolation algorithm of the adaptive feedrate control is proposed. According to the actual machining capacity of machine tools, this algorithm uses look-ahead method, which dispenses with the complicated computation of the end point estimation of NURBS curve, to analyze the curve segment required by the maximum deceleration distance. Thus, the feedrate could decrease in advance and vary with the curvature and the variation ratio of curvature, which makes machining motion quite smooth. Not only could high accuracy and fine surface quality be achieved during high-speed machining, but also the overload of cutter tools is avoided on comers. Finally, in order to facilitate the calculation of interpolation, the dynamic matrix representation and efficient algorithm of curvature computation of the NURBS curve are presented,

关键词： CNC NURBS curve interpolation high-speed machining

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Microstructure and cutting performance of CrTiAlN coating for high-speed dry milling

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Transactions of Nonferrous Metals Society of China 2014年第6期24卷 1800-1806页

作者：鲁力王启民陈柄洲敖永翠余东海王成勇伍尚华 Kwang Ho KIM 广东工业大学机电工程学院广州510006 昆山克顿纳米镀层科技有限公司苏州215000 National Core Research Center for Hybrid Materials Solution Pusan National University

Using a closed field unbalanced magnetron sputtering system,the cemented carbide end mills were coated with a CrTiAlN hard coating,which consisted of a Cr adhesive layer,a CrN interlayer and a CrTiAlN top *** microstructure and mechanical properties of the coating were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,micro indentation and scratch *** cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel（P20,HRC 45）.The results indicates that the coating is composed of（Cr,Ti,Al）N columnar grains with *** coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 *** coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated *** the related mechanisms were discussed.

关键词： CrTiAlN coating high-speed machining hardened steel tool wear

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Research Progress of Key Technology of high-speed and high Precision Motorized Spindles

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International Journal of Plant Engineering and Management 2005年第2期10卷 70-76页

作者： XIONGWan-li MIHai-qing HUANGHong-wu NationalResearchCenterforhighEfficiencyGrinding HunanUniversityChangsha410082P.R.China

high speed machining and high precision machining are two tendencies of themanufacturing technology worldwide. The motorized spindle is the core component of the machine toolsfor achieving the high speed and high precise machining, which affects the general developmentlevel of the machine tools to a great extent. Progress of the key techniques is reviewed in thispaper, in which the high speed and high precision spindle bearings, the dynamical and thermalcharacteristics of spindles, the design technique of the high frequency motors and the drivers, theanti-electromagnetic damage technique of the motors, and the machining and assembling technique areinvolved. Finally, tha development tendencies of the motorized spindles are presented.

关键词： motorized spindles high-speed machining

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