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111.
对于复杂微细、错边量小的激光焊接拼缝测量,现有的视觉传感器方法不能稳定、可靠地提取出拼缝的中心位置、拼缝宽度等信息。为此,提出了基于微景深的激光焊接对接拼缝测量方法,该方法采用高倍光学放大镜头、工业CCD(Charge Coupled Device)/CMOS(Complementary Metal-Oxide-Semiconductor Transistor)相机和LED(Light-Emitting Diode)外部照明装置,以光学成像光轴与被测表面法矢呈45°的方式,组成的对接拼缝的非接触测量系统,既解决了显微放大时景深很小、测量范围小的问题,又解决了狭窄拼缝高光学放大倍数拼缝检测的难题。实验结果表明,该系统可快速准确地提取出拼缝中心坐标、拼缝宽度以及拼缝局部表面法矢。拼缝宽度测量精度优于5 μm,拼缝中心测量精度优于6 μm,可识别的最小拼缝宽度为0.02 mm,完全满足激光焊接对接狭窄拼缝的检测与自动跟踪的要求。 相似文献
112.
Irving Kaufman Pan-Tze Chang Hsueh-Shun Hsu Wen-Yuan Huang Daw-Yang Shyong 《Journal of Nondestructive Evaluation》1987,6(2):87-100
This paper discusses surface crack detection by photothermal radiometric imaging (PRI). In PRI, also called dynamic infrared scanning, a surface is scanned with a spot of heat. Imperfections are detected by radiometrically sensing changes in the surface temperature of a small area in the vicinity of this spot. In the work described, cracks narrower than 25 µm (0.001 in.) in a lightly rusted steel surface have been detected. Indiscrete scanning an amplitude modulated heating beam is moved in steps, remaining at each location long enough to measure amplitude and phase of the AC temperature. Incontinuous scanning a constant intensity heating beam is moved continuously while the temperature deviations are measured. This paper presents methods of calculating amplitude and phase of surface temperature for discrete scanning and instantaneous temperature for continuous scanning across a surface crack. For a steel surface scanned by a watt-level laser beam, predicted surface temperature deviations when crossing the crack are several degrees Celsius, with expected radiometrically detected power several orders of magnitude above the detector noise. In experiments performed, both techniques easily detected narrow cracks in a smooth, clean surface. Discolorations and pits, on the other hand, generate a disturbing type of surface noise. This noise was minimized by differential detection. Based on results obtained, continuously scanned PRI with a fan-type heating beam and array detection could become a viable way of mapping surface cracks at practical scanning speeds. 相似文献
113.
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115.
焊接生产规模不断向自动化和流水线方式发展 ,对生产管理水平提出了更高的要求。为了从车间已积累的大量的生产历史数据中获得潜在的规律性和趋势 ,为管理者提供决策支持 ,文中在已有的质量在线监测平台和数据库系统上开发了基于先进的数据挖掘技术的焊接生产管理平台 ,同时为了获得有效的挖掘模式 ,对数据进行了预处理 ,建立了焊接车间数据集市。该平台主要使用控制图控制焊接生产产量和废品数量 ;利用决策树方法分析废品产生因素 ,获得了有效的挖掘模型 ,对于指导焊接生产具有重要意义 相似文献
116.
Material flow and microstructure in the friction stir butt welds of the same and dissimilar aluminum alloys 总被引:20,自引:0,他引:20
The material flow and microstructural evolution in the friction stir welds of a 6061-Al alloy to itself and of a 6061-Al alloy
to 2024-Al alloy plates of 12.7 mm in thickness were studied under different welding conditions. The results showed that plastic
deformation, flow, and mechanical mixing of the material exhibit distinct asymmetry characteristics at both sides of the same
and dissimilar welds. The microstructure in dissimilar 6061-Al/2024-Al welds is significantly different from that in the welds
of a 6061-Al alloy to itself. Vortex-like structures featured by the concentric flow lines for a weld of 6061-Al alloy to
itself, and alternative lamellae with different alloy constituents for a weld of 6061-Al to 2024-Al alloy, are attributed
to the stirring action of the threaded tool, in situ extrusion, and traverse motion along the welding direction. The mutual
mixing in the dissimilar metal welds is intimate and far from complete. However, the bonding between the two Al-alloys is
clearly complete. Three different regions in the nugget zone of dissimilar 6061-Al/2024-Al welds are classified by the mechanically
mixed region (MMR) characterized by the relatively dispersed particles of different alloy constituents, the stirring-induced
plastic flow region (SPFR) consisting of alternative vortex-like lamellae of the two Al-alloys, and the unmixed region (UMR)
consisting of fine equiaxed grains of the 6061-Al alloy. Within all of these three regions, the material is able to withstand
a very high degree of plastic deformation due to the presence of dynamic recovery or recrystallization of the microstructure.
The degree of material mixing, the thickness of the deformed Al-alloy lamellae, and the material flow patterns depend on the
related positions in the nugget zone and the processing parameters. Distinct fluctuations of hardness are found to correspond
to the microstructural changes throughout the nugget zone of dissimilar welds. 相似文献
117.
绝缘门极双极性晶体管(IGBT)在焊接逆变器中的应用 总被引:2,自引:0,他引:2
本文介绍绝缘门极双极性晶体管(IGBT)的基本结构、工作原理、开关特性以及在焊接逆变器中的应用。 相似文献
118.