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    2017年 第5卷 第2期    刊出日期:2017-06-25
    Adaptive pass planning and optimization for robotic welding of complex joints
    H. C. Fang, S. K. Ong, A. Y. C. Nee
    2017, 5(2):  93-104.  doi:10.1007/s40436-017-0181-x
    摘要 ( 510 )   PDF (1913KB) ( 1267 )  
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    Current industrial robotic welding systems cannot achieve automated solutions for multi-layer multi-pass welding of complex joints due to the presence of nonuniform and irregular welding groove geometries. This paper presents an adaptive pass planning approach for robotic welding of such complex joints. The welding groove is first segmented considering both the variation in groove dimension and the reachability of the robot welding torch. For each welding segment, the welding passes are planned to be in accordance with welding practices, viz., keeping the same number of welding passes in each layer while maintaining consistent welding parameters. An adaptive pass adjustment scheme is developed to address the discrepancies between the simulated results and the actual welding deposition after finishing a few layers of welding. Corresponding robot paths are generated and optimized to ensure minimum joint movement subject to three constraints, viz., reachability, collision-free and singularity avoidance. The proposed approach has been simulated with the arc welding of a Y-type joint found typically in offshore structures.

    State-of-the-art developments in metal and carbon-based semiconducting nanomaterials: applications and functions in spintronics, nanophotonics, and nanomagnetics
    Sergio Manzetti, Francesco Enrichi
    2017, 5(2):  105-119.  doi:10.1007/s40436-017-0172-y
    摘要 ( 387 )   PDF (1311KB) ( 8727 )  
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    Nanomaterials composed of metals and metal alloys are the most valuable components in emerging micro- and nano-electronic devices and innovations to date. The composition of these nanomaterials, their quantum chemical and physical properties, and their production methods are in critical need of summarization, so that a complete state of the art of the present and future of nanotechnologies can be presented. In this review, we report on the most recent activities and results in the fields of spintronics, nanophotonics, and nanomagnetics, with particular emphasis on metallic nanoparticles in alloys and pure metals, as well as in organic combinations and in relation to carbon-based nanostructures. This review shows that the combinatory synthesis of alloys with rare metals, such as scandium, yttrium, and rare earths imparts valuable qualities to high-magnetic-field compounds, and provides unique properties with emphasis on nanoelectronic and computational components. In this review, we also shed light on the methods of synthesis and the background of spintronic, nanomagnetic, and nanophotonic materials, with applications in optics, diagnostics, nanoelectronics, and computational nanotechnology. The review is important for the industrial development of novel materials, and for summarizing both fabrication and manufacturing methods, as well as principles and functions of metallic nanoparticles.

    Friction identification and compensation design for precision positioning
    Feng-Tian Li, Li Ma, Lin-Tao Mi, You-Xuan Zeng, Ning-Bo Jin, Ying-Long Gao
    2017, 5(2):  120-129.  doi:10.1007/s40436-017-0171-z
    摘要 ( 435 )   PDF (1406KB) ( 314 )  
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    Precision positioning systems driven by linear motors are vulnerable to force disturbances owing to the reduction of gear transmission. The friction, included in the disturbance, can be modeled and compensated to improve the servo performance. This paper proposes a modified Stribeck friction model (SFM) and an optimization algorithm for consistency with the positioning platform. The compensators based on the friction model and disturbance observer (DOB) are simulated. The simulation results show that as compared with the DOB compensator (the velocity recovers by 5.19%), the friction model based compensator (the velocity recovers by 10.66%) exhibits a better performance after adding the disturbance. Moreover, compensation comparisons among the Coulomb friction, traditional SFM, and modified SFM are performed. The experimental results show that the following error with modified SFM compensation improves by 67.67% and 51.63% at a speed of 0.005 m/s and 0.05 m/s, compared with the Coulomb friction compensation. This demonstrates that the proposed model, optimization algorithm, and compensator can reduce the following error effectively.

    On the wavelet analysis of cutting forces for chatter identification in milling
    Cesar Giovanni Cabrera, Anna Carla Araujo, Daniel Alves Castello
    2017, 5(2):  130-142.  doi:10.1007/s40436-017-0179-4
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    Chatter vibrations in machining operations affect surface finishing and tool behaviour, particularly in the end-milling of aluminum parts for the aerospace industry. This paper presents a methodological approach to identify chatter vibrations during manufacturing processes. It relies on wavelet analyses of cutting force signals during milling operations. The cutting-force signal is first decomposed into an approximation/trend sub-signal and detailed subsignals, and it is then re-composed using modified subsignals to reduce measurement noise and strengthen the reference peak forces. The reconstruction of the cuttingforce signal is performed using a wavelet denoising procedure based on a hard-thresholding method. Four experimental configurations were set with specific cutting parameters using a workpiece specifically designed to allow experiments with varying depths of cut. The experimental results indicate that resultant force peaks (after applying the threshold to the detailed sub-signals) are related to the presence of chatter, based on the increased correlation of such peaks and the surface roughness profiles, thereby reinforcing the applicability of the proposed method. The results can be used to control the online occurrence of chatter in end-milling processes, as the method does not depend on the knowledge of cutting geometry nor dynamic parameters.

    Influence of pulse magneto-oscillation on the efficiency of grain refiner
    Tian-Yu Liu, Jie Sun, Cheng Sheng, Qi-Xin Wang, Yun-Hu Zhang, Li-Juan Li, Hong-Gang Zhong, Qi-Jie Zhai
    2017, 5(2):  143-148.  doi:10.1007/s40436-017-0175-8
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    Solidification experiments were carried out in Al-Cu (w(Cu) = 5%) alloy to investigate the influence of pulse magneto-oscillation (PMO) on the efficiency of the Al3Ti1B refining agent at high superheat. The experimental solidification results show that the degree of superheat has remarkable influence on the efficiency of the grain refiner. However, the application of PMO has the potential to reduce the influence of superheat variation on the efficiency of the grain refiner. Finally, the mechanism underlying this phenomenon is discussed by performing a numerical simulation to show the forced flow inside the melt caused by PMO.

    Development and experimental investigation of duplex turning process
    Ravindra Nath Yadav
    2017, 5(2):  149-157.  doi:10.1007/s40436-017-0177-6
    摘要 ( 497 )   PDF (1414KB) ( 372 )  
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    The aim of the present study was to develop a novel turning process with the simultaneous application of two cutting tools in place of a single cutting tool during machining of rotating surfaces. This process is referred to as duplex turning, and is used to eliminate the need for a secondary final cut operation following the turning process. To achieve this, a secondary (auxiliary) tool post is mounted on the cross slide of the centre lathe machine after fabrication. The secondary tool post is used to hold a secondary cutting tool that penetrates the workpiece from opposite side of the primary cutting tool to perform the finish cut operation during turn machining of the cylindrical workpiece. The performance of the developed process was tested on AISI 1040 alloy steel, using two single point cutting tools made of high speed steel. The effects of cutting velocity, feed rate, primary depth of cut and secondary depth of cut were analyzed and discussed with regard to average surface roughness, and were also compared with normal turning process. From the results, it was concluded that duplex turning process was capable of providing better surface finishes compared to those generated by normal turning. It was also found that higher cutting velocity yielded better surface finishes within the determined ranges of the selected parameters.

    A medical image encryption algorithm based on synchronization of time-delay chaotic system
    Hua Wang, Jian-Min Ye, Hang-Feng Liang, Zhong-Hua Miao
    2017, 5(2):  158-164.  doi:10.1007/s40436-017-0178-5
    摘要 ( 439 )   PDF (957KB) ( 376 )  
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    This paper presents a new synchronization method of the time-delay chaotic system and its application in medical image encryption. Compared with the existing techniques, the error system is greatly simplified because many coupled items can be considered zero items. An improved image encryption scheme based on a dynamic block is proposed. This scheme divides the image into dynamic blocks, and the number of blocks is determined by a previous block cipher. Numerical simulations are provided to illustrate the effectiveness of the proposed method.

    A review of thickness-induced evolutions of microstructure and superconducting performance of REBa2Cu3O7-δ coated conductor
    Jian-Xin Lin, Xu-Ming Liu, Chuan-Wei Cui, Chuan-Yi Bai, Yu-Ming Lu, Feng Fan, Yan-Qun Guo, Zhi-Yong Liu, Chuan-Bing Cai
    2017, 5(2):  165-176.  doi:10.1007/s40436-017-0173-x
    摘要 ( 630 )   PDF (2814KB) ( 421 )  
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    The research and development of high temperature superconducting (HTS) films, especially ReBa2Cu3-O7-δ (REBCO or RE123; RE=Y, Gd, or other rare earths) yttrium-based coated conductors, has generated widespread interest for the potential applications of the second generation superconducting films. In view of commercialization, however, the maximum superconducting currents for coated conductors should be increased further. Unfortunately, it has been frequently observed that the average critical current density Jc decreases with an increase in film thickness. The thickness effect is still a hurdle for largescale production, especially in pulsed laser deposition and metal organic deposition processes. An engineering current of more than 1 000 A/cm is desired owing to the high cost of 2G superconducting materials. The present work attempts to review the evolution of various issues subject to the thickness effect, including the microstructure, epitaxial texture, surface roughness, pinning force, oxygen deficiency, residual stress, copper-rich layers, and segregation of elements. Furthermore, recent progress in enhancing the performance of superconductors especially in terms of critical current density is illustrated, such as the use of heavy doping. Further understanding of the thickness effect is extremely important for large-scale commercial development of the second generation high temperature superconductors.

    Roundness measurement of cigarette based on visual information
    Jun-Li Cao, Ju-Feng Li, Teng-Da Lu
    2017, 5(2):  177-181.  doi:10.1007/s40436-017-0176-7
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    Roundness is defined as the degree that the cross section of an object is close to a theoretical circle. In the cigarette production process, the quality and production efficiency of a cigarette are directly affected by the roundness of the un-cut cigarette. To improve the current measurement method using a charge-coupled device (CCD) sensor and measure the roundness of cigarettes in the production line, a visual detection system composed of an industrial camera and a structural light is developed. The system's roundness-calculation method is closer to the real environment of the cigarette roundness. In this visual system, the line-structure light shines on the cigarette with a fixed angle and height in a longitudinal section, forming a crescent-shaped spot when the industrial camera cannot capture the cigarette's end surface. Then, the spot is analyzed using image-processing techniques, such as a median filter and ellipse fitting, after the industrial camera captures the spot. The system with a non-contact measurement style can meet the requirements of on-line cigarette detection with stable results and high precision.

    A wheel-type in-pipe robot for grinding weld beads
    Zi-Li Xu, Song Lu, Jun Yang, Yong-Hui Feng, Chun-Tai Shen
    2017, 5(2):  182-190.  doi:10.1007/s40436-017-0174-9
    摘要 ( 386 )   PDF (1518KB) ( 642 )  
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    To improve the safety and efficiency of polishing operations in circular boiler headers, a new type of wheel-drive polishing robot was developed in this study. The robot was designed to grind weld beads on the inner walls of pipes in diameter between 550 mm and 714 mm. The robot consists of a moving structure, a positioning structure, and a polishing structure. Charge coupled device (CCD) cameras and line lasers are used in the robot's vision system, thus the robot can be manually controlled to move, locate, and grind quickly and accurately. The experimental results showed that the robot performed well in practical applications.

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