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91.
OpticalMeasuringMethodforQualityMonitoringPurposeinLaserWeldingofTin-plates¥LUOHong;HULunji;HUANGShuhuai;LIZhiyuan;HUXiyuan(H... 相似文献
92.
介绍了一种在无冷柱头进样器和特殊注射器情况下简便可行的冷柱头进样技术。以海洛因、秋水仙碱、正三十烷醇为研究对象,考察了本方法的定性、定量偏差,提出两种溶质聚焦方法。 相似文献
93.
焊接变形光学测量技术研究 总被引:1,自引:0,他引:1
针对薄板焊接变形测量难的问题,提出了一种非接触式三维光学实时测量薄板焊接变形的新方法。首先通过2个高分辨率高速数字相机从不同观察点同时拍摄物体运动的视频图像;然后运用三维重建技术,包括共线方程、基于共面方程的像片定向、直接线性变换解法、外极线几何约束和光束平差解法等重建待测标志点的三维坐标;最后依据同名点将不同时刻薄板的变形状态关联起来,计算出待观测点的焊接变形量,并实时绘制显示出变形曲线。与传统方法相比,该方法具有不受焊接温度及强烈干扰影响和实时、高效、高精度等优点。 相似文献
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95.
New absorption cells designed specifically to achieve stable temperatures down to 66 K inside the sample compartment of an evacuated Bruker IFS-125HR Fourier transform spectrometer (FTS) were developed at Connecticut College and tested at the Jet Propulsion Laboratory (JPL). The temperature stabilized cryogenic cells with path lengths of 24.29 and 20.38 cm were constructed of oxygen free high conductivity (OFHC) copper and fitted with wedged ZnSe windows using vacuum tight indium seals. In operation, the temperature-controlled cooling by a closed-cycle helium refrigerator achieved stability of ±0.01 K. The unwanted absorption features arising from cryodeposits on the cell windows at low temperatures were eliminated by building an internal vacuum shroud box around the cell which significantly minimized the growth of cryodeposits. The effects of vibrations from the closed-cycle helium refrigerator on the FTS spectra were characterized. Using this set up, several high-resolution spectra of methane isotopologues broadened with nitrogen were recorded in the 1200-1800 cm−1 spectral region at various sample temperatures between 79.5 and 296 K. Such data are needed to characterize the temperature dependence of spectral line shapes at low temperatures for remote sensing of outer planets and their moons. Initial analysis of a limited number of spectra in the region of the R(2) manifold of the ν4 fundamental band of 13CH4 indicated that an empirical power law used for the temperature dependence of the N2-broadened line widths would fail to fit the observed data in the entire temperature range from 80 to 296 K; instead, it follows a temperature-dependence similar to that reported by Mondelain et al. [17] and [18]. The initial test was very successful proving that a high precision Fourier transform spectrometer with a completely evacuated optical path can be configured for spectroscopic studies at low temperatures relevant to the planetary atmospheres. 相似文献
96.
Salman Iqbal Author Vitae Muddassir M.S. Gualini Author Vitae Author Vitae 《Optics & Laser Technology》2010,42(1):93-98
Laser welding of zinc-coated steel sheets in lap configuration poses a challenging problem, because of the zinc vapours spoiling the quality of the weld. In continuation to the earlier work, the novel solution of dual laser beam method for lap welding of galvanized steel sheets is discussed here in view of the recently obtained observations and ensuing concerns. In this method the precursor beam cuts a slot, thus making an exit path for the zinc vapours, while the second beam performs the needed welding. The metallurgical analysis of the welds is encouraging showing absence of zinc in the welded area. In the current work on this technique, new experimental results have been obtained verifying the earlier observations. Along with this, the possibility of using a transversely split-up beam for the welding purposes with this approach is discussed and analyzed in this paper. This new technique is expected to be very useful in prospective industrial applications requiring higher welding throughput along with the needed quality. 相似文献
97.
Jean-Pierre Planckaert El-Hadi Djermoune David Brie Francis Briand Frédéric Richard 《Applied Mathematical Modelling》2010
This paper investigates some issues in physical modeling of metal inert gas/metal active gas (MIG/MAG) welding process in the short arc mode. In this mode, a metal supply is molten in the arc state and then transferred to the weld pool during the short-circuit state. A hybrid model having two distinct continuous states whose switchings are controlled by two guard conditions is proposed. Due to the complexity of the physical phenomena involved in the welding process, simplifications are used to obtain a model accounting for the main physical contributions but simple enough to yield an efficient, fast and numerically tractable simulator which can be used intensively for evaluating different control strategies. In an attempt to validate the proposed model, different measurements have been made including supply voltage and current sampled synchronously with high speed digital video. In order to extract some relevant quantities representative of the metal transfer from image sequences, an active contour algorithm is developed and tested. The effectiveness of the proposed model in the prediction of major tendencies of a welding process, especially in the arc state, is shown using experimental data. Some limitations of the model during the metal transfer are also stressed and possible remedies are then proposed. 相似文献
98.
99.
100.
A three-dimensional model of multiple reflections for high-speed deep penetration laser welding based on an actual keyhole 总被引:1,自引:0,他引:1
Keyhole shapes are observed experimentally by two high-speed cameras from two perpendicular directions in high-speed laser welding of glass. From the obtained keyhole pictures, it can be seen that in high-speed deep penetration laser welding, the keyhole is not only seriously bent in the direction opposite to that of welding speed, but also elongated along the direction of the welding speed. Based on the so-obtained keyhole photograph, the keyhole profiles in both the symmetric plane and its perpendicular plane (i.e., the cross-section plane) are determined by the method of polynomial fitting. Then, under the assumption of elliptical cross-section of the keyhole at each keyhole depth, a 3D bending keyhole is reconstructed, the behavior of focused Gaussian laser beam in the keyhole is analyzed by tracing a ray of light using geometrical optics theory. Fresnel absorption and multiple reflections in the keyhole are systematically studied, and the laser intensities absorbed on the keyhole walls are calculated. In determining the distribution of laser intensity on the keyhole wall, the bending of the keyhole plays the dominant role, elongation of the keyhole plays just a minor role. Because of the bending of the keyhole, not all the keyhole wall can be irradiated directly by laser beam. The absorbed laser intensity cannot be uniformly distributed on the keyhole wall even after multiple reflections. The keyhole wall absorbs laser intensity mainly on the small area near the front keyhole wall. Recoil pressure plays a dominant role in forming a keyhole and keeping it open. 相似文献