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Computer numerical control (CNC) machine tools are widely used in various industrial fields ranging from aerospace, automotive, ship building, and the die/mould to manufacture products. However, tool paths of most CNC machine tools are composed of a series of linear motion commands (G01), which will inevitably cause the discontinuity in curvature and feedrate at the junctions between adjacent linear tool path segments, deteriorating the surface quality with unfavorable marks and decreasing the machining efficiency. To solve this problem for obtaining the steady and continuous motions of machine tools, the local corners have to be smoothed. Generally, the existing corner smoothing methods can be classified as the global smoothing and the local corner smoothing, where the specially designed transition curves or the directly planned motion of machine tools are adopted to generate the geometrically corner-free tool path. Moreover, some new methods that focus on developing different transition or rounding strategies are also developed for further improving the kinematics performance of machine tools. In this paper, the recent advances and researches on corner smoothing methods are reviewed from different categories, and the conclusions, remaining challenges and future directions in corner smoothing are also presented.
Computer numerical control (CNC) machine tools are widely used in various industrial fields ranging from aerospace, automotive, ship building, and the die/mould to manufacture products. However, tool paths of most CNC machine tools are composed of a series of linear motion commands (G01), which will inevitably cause the discontinuity in curvature and feedrate at the junctions between adjacent linear tool path segments, deteriorating the surface quality with unfavorable marks and decreasing the machining efficiency. To solve this problem for obtaining the steady and continuous motions of machine tools, the local corners have to be smoothed. Generally, the existing corner smoothing methods can be classified as the global smoothing and the local corner smoothing, where the specially designed transition curves or the directly planned motion of machine tools are adopted to generate the geometrically corner-free tool path. Moreover, some new methods that focus on developing different transition or rounding strategies are also developed for further improving the kinematics performance of machine tools. In this paper, the recent advances and researches on corner smoothing methods are reviewed from different categories, and the conclusions, remaining challenges and future directions in corner smoothing are also presented.
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Carbon fiber-reinforcement plastics (CFRP) have been widely applied in modern aerospace industry with aluminum alloy in the form of thin-walled stacks due to their superior mechanical and physical properties. However, for CFRP, the heat accumulation occurs easily during countersinking process in consequence of low thermal conductivity. The surface thermal damage of CFRP caused by excessive heat would affect the fatigue and stealth performance of aircraft. Consequently, the countersinking temperature is an important indicator to judge the feasibility of CFRP countersinking process. In this paper, to investigate temperature of countersinking process, the application of rotary ultrasonic machining technology to CFRP/Al thin-walled stacks countersinking process under different stiffness conditions with drilling-countersinking integrated tool is carried out by FEA (Finite element analysis) and experiments. And the influences of cutting temperature on countersunk wall quality are discussed. The results demonstrate that the maximum countersinking temperature increases with the decrease of axial stiffness, and the ultrasonic vibration can effectively reduce maximum countersinking temperature by 22.9%-26.2%. Furthermore, analysis of the surface quality of countersunk wall shows that the countersunk wall roughness and defects gradually deteriorate with the increase of the maximum countersinking temperature. Meanwhile, the ultrasonic vibration can improve countersunk surface quality by reducing maximum countersinking temperature effectively.
Carbon fiber-reinforcement plastics (CFRP) have been widely applied in modern aerospace industry with aluminum alloy in the form of thin-walled stacks due to their superior mechanical and physical properties. However, for CFRP, the heat accumulation occurs easily during countersinking process in consequence of low thermal conductivity. The surface thermal damage of CFRP caused by excessive heat would affect the fatigue and stealth performance of aircraft. Consequently, the countersinking temperature is an important indicator to judge the feasibility of CFRP countersinking process. In this paper, to investigate temperature of countersinking process, the application of rotary ultrasonic machining technology to CFRP/Al thin-walled stacks countersinking process under different stiffness conditions with drilling-countersinking integrated tool is carried out by FEA (Finite element analysis) and experiments. And the influences of cutting temperature on countersunk wall quality are discussed. The results demonstrate that the maximum countersinking temperature increases with the decrease of axial stiffness, and the ultrasonic vibration can effectively reduce maximum countersinking temperature by 22.9%-26.2%. Furthermore, analysis of the surface quality of countersunk wall shows that the countersunk wall roughness and defects gradually deteriorate with the increase of the maximum countersinking temperature. Meanwhile, the ultrasonic vibration can improve countersunk surface quality by reducing maximum countersinking temperature effectively.
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Mg-2Zn-1Al alloy was used as the matrix, and 0.2wt% Ca, 0.2wt% Gd, and 0.2wt% Ca+0.2wt% Gd were added into it. The target alloys with four components were extruded at 200℃ and extruded bars with good surface quality were obtained. Optical microscope (OM), scanning electron microscope (SEM), X-ray (XRD) and tensile mechanics experiment were adopted to analyze the effect of trace Ca and Gd on the microstructure and mechanical properties of Mg-2Zn-1Al alloy. It is found that the grain size of the as-cast matrix alloy can be refined by adding Ca and Gd, and the effect of grain refinement was the superposition of the two effects added separately. This is due to the heterogeneous nucleation of Al2Ca and the segregation of Gd in front of the solid-liquid interface leads to the inhibition of grain growth. Furthermore, the addition of Ca and Gd can make the extruded micro-structure fine and uniform, which can weak the texture to improve the mechanical properties of the alloy. And the composite addition has the best refinement effect and texture weakening effect. Therefore, the alloy with the composite addition of the two showed the best mechanical properties.
Mg-2Zn-1Al alloy was used as the matrix, and 0.2wt% Ca, 0.2wt% Gd, and 0.2wt% Ca+0.2wt% Gd were added into it. The target alloys with four components were extruded at 200℃ and extruded bars with good surface quality were obtained. Optical microscope (OM), scanning electron microscope (SEM), X-ray (XRD) and tensile mechanics experiment were adopted to analyze the effect of trace Ca and Gd on the microstructure and mechanical properties of Mg-2Zn-1Al alloy. It is found that the grain size of the as-cast matrix alloy can be refined by adding Ca and Gd, and the effect of grain refinement was the superposition of the two effects added separately. This is due to the heterogeneous nucleation of Al2Ca and the segregation of Gd in front of the solid-liquid interface leads to the inhibition of grain growth. Furthermore, the addition of Ca and Gd can make the extruded micro-structure fine and uniform, which can weak the texture to improve the mechanical properties of the alloy. And the composite addition has the best refinement effect and texture weakening effect. Therefore, the alloy with the composite addition of the two showed the best mechanical properties.
A short review on milling dynamics in low-stiffness cutting conditions: Modeling and analysis
Machining process monitoring and application: a review
On-line tool wear monitoring based on machine learning
Electrochemical discharge machining for fabricating holes in conductive materials: A review
Prediction and suppression of chatter in milling of structures with low-rigidity: A review
Intelligent forming technology: State-of-the-art review and perspectives
Titanium alloy material has excellent properties such as low density, high strength, good oxidation resistance, creep resistance, etc. It has a broad application prospect in various fields. However, these characteristics also make it dif-ficult to process. Grinding is an essential method for high efficiency and precision machining of titanium alloy, ob-taining good machining precision and surface quality. The removal mechanism of titanium alloy is helpful to im-prove the surface quality of titanium alloy grinding. The recent research results in this field are reviewed. Firstly, the grinding technology types of titanium alloy were summarized, and the machining characteristics were systematically analyzed from two aspects of abrasive wear and material removal behavior of titanium alloy. Finally, the development trend of titanium alloy grinding technology in the prospect.
Machining data have been increasingly crucial with the development of modern manufacturing strategies, and the explosive growth of data amount revolutionizes how to collect and analyze data. In machining process, anomalies such as machining chatter and tool wear occur frequently, which strongly affect the process by reducing accuracy and quality as well as increasing the time and cost. As a typical type of machining data, signals acquired in real time by advanced sensor techniques are widely embraced to detect those anomalies. This paper reviews the recent development and applications of process monitoring technologies in machining processes, and typical application scenarios in machining processes are discussed with the latest literatures and current research issues. Potential future trends of process data monitoring and analysis for intelligent machining are put forward at the end of the paper.
The processed surface integrity of the propeller has a vital impact on the performance, efficiency, and noise of the entire power energy conversion device, and the bionic micro-structured surface is conducive to improving the noise reduction performance of the working parts. In this paper, the microstructure of the propeller blade surface is machined by precision abrasive belt grinding. Based on the surface roughness detection and 3D morphology analysis results, a univariate model of propeller surface groove with V-shaped section is established. The flow field analysis, numerical analysis of cavitation, and noise performance analysis of general marine propellers and bionic marine propellers are also carried out. The results show that the maximum noise of the propeller with the bionic grooved surface is 94.7 decibels, and the maximum noise of the general propeller is 146 decibels. The noise reduction effect is increased by 35%, which provides a new method of precision abrasive belt grinding for the noise reduction of the propeller.
Compared with traditional additive manufacturing technology (3D printing), 4D printing technology (four-dimensional printing) increases the time dimension. The structure prepared by 4D printing process can change its shape and configuration with the external environment (i.e. light, heat, magnetism, electricity, etc.), which has a broad application prospect. This paper introduces several typical implementation methods of 4D printing in combination with the typical research results of 4D printing in recent years. The printing materials, design methods, and simulation methods of current 4D printing technology are summarized. Finally, the possible development directions of 4D printing technology and its application prospects in the fields of biomedicine, soft robotics, aerospace, etc. are introduced, and some problems of 4D printing technology are discussed.
The rapid development of artificial intelligence (AI) technology makes it possible for achieving intelligent forming. It will bring great breakthrough of material forming technology, realizing the unmanned watching, intelligent processing design and intelligent control during forming process. Moreover, it can greatly improve the forming accuracy, mechanical properties, forming efficiency and economic benefits, and promote the continuous emergence of new forming technology. Thus, the intelligent forming technology, integrating AI technology and advanced forming technology, has become an international research focus. This paper reviews the recent developments of intelligent forming technology from four kinds of common forming technology, i.e., intelligent casting, intelligent plastic forming, intelligent welding, and intelligent additive manufacturing. Moreover, the current research issues and future trends of intelligent forming technology are put forward at the end of the paper.
The dynamic responses of milling system change the ideal trajectories of cutting teeth and therefore plays a critical role in determining the machining accuracy. The amplitude of cutting vibrations could reach tens of or even hundreds of micrometers in low-stiffness cutting conditions, for example, when milling thin-walled parts and/or using slender tools. Usually, moderate cutting parameters are utilized to avoid excessive cutting loads, strong milling chatter or large dynamic deflections, which however, significantly lowers the productivity. In spite of decades of study, it is still a challenge to accurately model, efficiently analyze, reliably monitor and precisely control the dynamic milling process in low-stiffness cutting conditions. In this paper, the recent advances and research challenges on dynamics modeling and response analysis are briefly reviewed.
Milling is widely used to machine the structures with low-rigidity in astronautic and aeronautic industries, while chatter vibration, which is a great limitation and a serious problem, is easy to occur in this kind of process due to the weak stiffness of the structures. To solve the machining problems caused by chatter, prediction and suppression are two important methods that are commonly used by researchers and industry engineers. This article reviews the study progresses on the prediction and suppression of the chatter occurring in milling process of the low-rigidity structure. The dynamic model, acquisition of dynamic parameters, and suppression techniques are introduced. Besides, the problems and the outlooks of the future coming research are also given in the conclusions.
Structured light method is one of the best methods for automated 3D measurement in industrial production due to its stability and speed. However, when the surface of industrial parts has high dynamic range (HDR) areas, e.g. rust, oil stains, or shiny surfaces, phase calculation errors may happen due to low modulation and pixel over-saturation in the image, making it difficult to obtain accurate 3D data. This paper classifies and summarizes the existing high dynamic range structured light 3D measurement technologies, compares the advantages and analyzes the future development trends. The existing methods are classified into multiple measurement fusion (MMF) and single best measurement (SBM) based on the measurement principle. Then, the advantages of the various methods in the two categories are discussed in detail, and the applicable scenarios are analyzed. Finally, the development trend of high dynamic range 3D measurement based on structed light is proposed.
Accurate tool condition monitoring is necessary for the development of automatic milling technology. In order to improve the accuracy and real-time of online monitoring of tool wear state in machining process, an online monitoring system of milling cutter state based on LabVIEW software development is proposed. Firstly, the modern monitoring technology is introduced into the online monitoring of tool state in principle. The vibration signal is analyzed by wavelet packet in time-frequency domain, and the online monitoring of tool state is realized by machine learning algorithm model. The system can be used for real-time monitoring of tool status, timely alarm to facilitate tool replacement, and ensure high efficiency and high quality of processing. The effectiveness and feasibility of the online monitoring system for milling cutter wear state are verified by experiments, and the purpose of online monitoring tool wear state is preliminarily realized.
The in-situ TiB2 particle reinforced Al-based metal matrix composites have become a series of promising aeronautical materials due to the advanced properties such as finer evenly-distributed grains, cleaner particle-matrix interface, improved mechanical performance and strength when compared with ex-situ SiC particle reinforced Al-based metal matrix composites. However, over the last 50 years, a significant body of research has been carried out on ex-situ SiC particle reinforced Al-based metal matrix composites from material fabrication process, material property improvement, material mechanical test to machining performance such as machined surface integrity, cutting process simulation and modeling, parameter optimization and fatigue characteristics. For in-situ TiB2 particle reinforced Al-based metal matrix composites, studies in recent years were mainly focused on the material preparation process and property development and few published works was found on the machining performance of this new kind material. Hence, this article aims to provide a general overview of recent achievement on machining performance of in-situ TiB2 particle reinforced Al-based metal matrix composites.
