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激光热处理应用研究中,当激光作用区临近工件边界时,防止边界熔化并让边界获得满意的热处理是必须认真处理的重要问题。实验研究表明,根据被处理工件的边界形状设计光阑并将光阑放在合适位置,可以有效地避免边界损伤并获得高质量的处理结果。为简化热作用研究,通常可以将被处理材料视为热物性参数为恒量的连续介质,而当处理工件的边界由相交平面边界构成时,可以通过引入适当的像热源来处理边界问题,因此,用这种热处理温度场的半解析计算方法可以满意地获得边界附近的瞬态温度场。提出了一种边界保护的简单方法,并利用激光热处理温度场的半解析计算方法作出证明。研究结果表明,合适选择边界保护宽度,不但能够有效保护边界,并能在边界附近得到深度均匀的硬化带。 相似文献
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友清 《激光与光电子学进展》1996,(12):33-34
激光冲击处理的新活力成立於1995年初的LSF技术公司(俄亥俄州都柏林)拥有巴特尔纪念研究所全世界唯一的实用激光冲击处理特许。激光冲击处理(LSP)适合需要或得益於局部压缩残留应力、塑料应变或冲击波的所有材料和制造应用。若干例子是用以提高疲劳寿命的喷... 相似文献
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激光冲击处理(LSP)(或激光喷丸强化)是利用激光冲击波压力对材料表面实施强化处理的一种新型表面处理技术。经激光冲击后,残余压应力在材料表面和深度方向上的分布和大小是评价激光冲击效果的一个重要指标,而有限元模拟(FEM)是预测激光冲击处理后残余应力场分布和大小的一种有效方法。在利用ABAQUS软件对激光冲击处理6061-T6铝合金进行数值分析时,讨论了有限元模型、材料性能、冲击加载方式、分析时间等关键问题的处理方法,并分析了激光冲击后残余应力场的分布特点,最后利用有限元模拟考察了激光冲击次数对残余应力场的影响。 相似文献
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激光表面合金化工艺在割草机刀片中的应用研究 总被引:1,自引:0,他引:1
通过合金化技术对割草机刀片进行激光表面处理,观察其微观组织,并通过耐磨性能和实际装机实验等手段对比分析。结果表明,经过激光处理能使65Mn材料割草机刀片硬度提高一倍左右,耐磨性提高2倍左右,寿命提高一倍左右。 相似文献
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激光材料加工技术的发展方向 总被引:1,自引:0,他引:1
范品忠 《激光与光电子学进展》2001,(11):46-48
激光在制造业中的应用特色是产品的高质量 ,加工的高效率 ,人工和用材的经济以及生态环境清洁。激光技术的发展有其社会效益 :为有能力的职工创造工作场所 ,这将促进教育和文化水平的提高。战略目的是保存和发展积累的技术和工业潜力 ,使其适应现代条件。激光加工多种多样 ,包括电子元件的精密微焊接、汽车和船舶制造中的焊接以及坯料制造中的切割。有不同种类的表面处理 ,如热处理、表面修整、合金化、打标等等。在激光帮助下许多方面已获得用其他方法不能实现的技术和经济效益。有许多用普通焊接方法实现的技术加工 ,从质量和产量的观点看… 相似文献
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径向三重流MOCVD反应器输运过程的数值模拟 总被引:4,自引:4,他引:0
对径向三重流MOCVD反应器的输运过程进行了二维数值模拟研究.在模拟计算中,分别改变反应腔几何尺寸、导流管位置、流量、压强、温度等条件,得到反应器流场、温场、浓度场的相应变化.根据对模拟结果的分析,发现反应腔内涡旋首先在流动的转折处产生,上下壁面温差的加大使涡旋增大,中管进口流量的增加对涡旋产生抑制作用,内管和外管流量的增加对涡旋产生扩大作用.得出输运过程的优化条件为:反应腔上下壁靠近,导流管水平延长,中管进口流量尽量大于内、外管流量,压强尽量低于10.5Pa,上下壁面温差尽量减小等. 相似文献
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大型天线座方位支承转动装置结构设计 总被引:5,自引:0,他引:5
介绍了某大型天线座方位支承转动装置的结构设计方案。该设计方案中采用了能同时承受径向力、轴向力和倾覆力矩的特大型钢丝滚道轴承。文中对钢丝滚道轴承的承载能力进行了校核,对主要结构件的刚度进行了分析计算。尤其是在钢丝滚道轴承的滚压磨合方法中提出的递增加载原则、载荷作用线与轴承旋转轴线重合原则和刚度原则。是工程设计和实践经验的总结。 相似文献
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毛化轧辊的新方法及其应用 总被引:16,自引:0,他引:16
用脉冲激光毛化轧辊既可精确控制辊面的形貌与粗糙度又能使辊面得到强韧化。在冷轧薄钢板(带)生产中,激光毛化轧辊比目前常用的喷丸毛化轧辊有更好的使用效果和更长的使用寿命,所轧薄板的质量也更为优异。 相似文献
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The measured intensity modulation (IM) and frequency modulation (FM) characteristics of single-cavity channeled-substrate buried-heterostructure (CSBH) lasers and cleaved-coupled-cavity (C3) CSBH lasers are described. If the bias is well above threshold, the lasers have -3 dB IM bandwidths of approximately 800 MHz. In contrast, the FM response rolls off less rapidly, and efficient FM operation up to 6 GHz is possible. The IM and FM responses of C3CSBH lasers are similar to single-cavity CSBH lasers provided the modulated cavity is above threshold. If the modulated cavity is below threshold, the FM response of the C3laser is larger but rolls off rapidly for modulation frequencies above 200 MHz. 相似文献
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Zecchetto S. De Biasio F. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(10):2257-2262
Synthetic aperture radar (SAR) images of the sea surface often show roll-vortex structures and other features which, in general, are spread out over several length scales and may present spatial periodicity as well as intermittence. Standard techniques, such as two-dimensional (2-D) Fourier analysis, are unsuitable both when it is of interest to detect intermittent phenomena and to analyze the spatial disposition of the backscatter structures inside the SAR images. For the above reasons, the 2-D continuous wavelet transform analysis has been applied to two European Remote Sensing mission SAR images over the Mediterranean Sea, showing wind rolls and atmospheric gravity waves. Through the evaluation of the wavelet variance map, which ideally corresponds to the 2-D Fourier spectrum, it has been possible to assess the presence of two main energy areas at large (from 7-28 km) and small (from 0.5-2 km) spatial scales. While the large-scale fluctuations may be ascribed to atmospheric gravity waves and other features induced by the surroundings, the small-scale fluctuations reveal the inner structure of the atmospheric wind rolls. The SAR-like maps, obtained by adding the wavelet coefficient maps pertaining to the small scales, have permitted us to highlight the high- and low-intensity backscatter cells associated with the wind rolls. These cells have been statistically characterized by means of the frequency distributions of the size of the cells maximum and minimum axes, of the orientation of the maximum axis, and of their area. The results indicate that high- and low-intensity backscatter cells have similar characteristics in both cases studied: they appear of elliptic shape, with the major axis along the wind roll direction; the average axes ratio is 2.5:1. The frequency distributions of the cell area indicate a continuous distribution of sizes, without significant gaps. 相似文献
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通过利用圆周长的展长等于圆在平面滚动一周的距离这一定义,设计由步进电机依据控制信号精确旋转,带动多组水平安装的圆柱形胶辊旋转所设定角度,将放置在胶辊上面的电路板精确输送到拍照位置,并对待检测电路板在前、侧限位后进行全自动光学检测。 相似文献
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Not in recent times has so much of the engineering force been on the unemployment rolls. Job seeking is never easy, and for many engineers the experience may be novel. This article covers the steps that the engineer job seeker should follow initially, and cites some of the dos and don'ts to help him sell himself. 相似文献
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The authors report the use of novel monolithic lateral photodetectors surrounding vertical-cavity surface emitting lasers to determine the radiative transition rate and lasing threshold independent from the axial emission. The lateral detector photocurrent increases with increasing laser drive current, even as the axial emission rolls over and terminates. This clearly establishes that laser output is limited by the detuning between the Fabry-Perot cavity resonance and the gain bandwidth with temperature, rather than the temperature dependence of the gain.<> 相似文献