Papers by Keyword: Laser Technique

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Authors: Yan Fang, Xi Chen Yang, Jian Bo Lei
Abstract: A repair method for damaged parts based on laser robot system is proposed. First, to obtain 3D point cloud in the robot coordinate system, damaged part surfaces are scanned with binocular stereo vision system, including camera calibration and image matching. Secondly, with the point cloud data and laser processing parameters, system accomplishes path planning, generates robot programs. Experimental results show that system can effectively achieves 3D reconstruction and path planning, which further enable high precision remanufacturing.
Authors: Fei Wang, Xi Chen Yang
Abstract: The powder feeder head is studied, which is one of the key to laser cladding. In view of many coaxial nozzles that are used nowadays, we have found that while cladding is doing, most of the nozzles have poor affect on powder-gathering. So as have researched on the theoretical and experiments, we designed a new coaxial nozzle, which has a great affect on powder-gathering, and can be modular disassembled. We have researched on powder stream theoretically, shot the morphology of powder stream by using high-resolution CCD camera, and analyzed the parameters of powder stream. And this new coaxial nozzle has been used in laser cladding experiments.
Authors: Yuan Yuan Gu, Guo Xing Wu, Hui Lu, Jian Lin
Abstract: Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. This is mainly due their poor output beam quality. Because of this, direct diode lasers are typically used to pump other lasers such as bulk solid-state (rod and thin disk) and fiber lasers. An improvement of the wall-plug efficiency and Power density necessary can be achieved by beam shaping and beam combination such as polarization coupling. In this paper, using the beam shaping technology realize good beam quality and high wall-plug efficiency. Base on bars rated to 60 W and 57% conversion efficiency, vertically stacked arrays (twenty bars) of such configuration are demonstrated with rated to about 1200W. The beam quality of high-power high brightness 880 nm laser diode source is improved with beam shaping. Beam parameter product of 79. 3 mm mrad ×81. 2 mm mrad, electro-optical conversion efficiency of more than 45.8% and continuous output power of 1 kW are demonstrated. This laser can be directly applied to cladding, surface hardening and other fields.
Authors: Seong Kyun Cheong, Young Bae Kim, Koung Suk Kim, Young June Kang
Authors: Hui Zheng, Guo Dong Wang, Zhi Ren Han
Abstract: In order to study the influence of the layer of the laser cladding to the bending degree, obtain the mathematical formulation in shaft laser cladding bending and derive the empirical formula, the laser cladding test for shaft was designed. The laser cladding test had been proceeded at the same cladding area and different layer of cladding. The results of the experiment show that the shaft is bended facing the laser beam. The bending degree and the layer of laser cladding are at the direct proportion. At the same time mathematical formulation in shaft laser cladding bending has been established and the parameter which is used to measure the degree of the bending has been obtained. Empirical formula between bending degree and the layer of laser cladding has been established. The circular run-out formula along the shaft length has been derived. The calculated value and the measured value are of the goodness fit. The maximal error is 0.035mm, and the average error is 0.017mm. It illustrates that the mathematic formulation is correct and the empirical formula has high accuracy.
Authors: Yuan Yuan Gu, Guo Xing Wu, Hui Lu, Yan Cui
Abstract: Laser diode has incited particular interest as photoelectric conversion efficiency, output power and lifetime for a variety of applications in industry processing. The single laser diode optical power has not satisfied for the actual requirements. It demands to couple several diode laser beams into one beam to output directly or by an optical fiber to improve the brightness, and it becomes the central issue to adopt the appropriate beam coupling technology which would offer high quality and high efficiency. In order to output high power, we utilized wavelength coupling technology to couple two laser beam of different wavelength together with beam splitter cube (BSC), the key technology and the principle of wavelength coupling is indicated and analyzed in this paper .Using 808nm and 980nm laser diode realize wavelength coupling with high output power, the efficiency more than 80% and spot size can be achieved after focusing to the beam size of 3×3mm2.
Authors: Nai Fei Ren, Rong Xiao Wang, Jia Fang Gu, Jian Qing Ren
Abstract: Cu films were deposited on Si and K9 glass substrates by magnetron sputtering technique. The influences of varying thicknesses and substrates on the transient reflectivity of Cu films were studied by using femtosecond laser pump-probe technology. The results show that the transient reflectivity curve of Cu films in different thicknesses have the same trend except that when they reach the peak value and recover to the balance. When the laser power is 40 mW, the influence of Si and K9 substrates on the transient reflectivity curve of 20 nm Cu films is relatively small. But when the laser power is160 mW, the influence of Si and K9 substrates on the transient reflectivity curve of 20 nm Cu films have obvious difference, the former needs much less time to reach the thermal equilibrium than of the later. At the same time, the influence of different substrates on the transient reflectivity curve of 200 nm Cu is also small.
Authors: Xiao Qing Zhang, Yu Dong Jia, Wen Juan Cao
Abstract: With the aim to determine parameter influences of a measurement system based on optical feedback interference in a laser diode, a mathematic model of optical feedback interference effect is built. LabVIEW which is a kind of graphical programming language is used to realize parameter setting and graphic display by front panel and program chart. Experimental results show that the stripes of optical feedback interference effect are saw-tooth-like waveform when feedback level factor is less than and close to 1, which can be used to determine moving direction of external reflecting object. Feedback interferences generate when vibration amplitude of reflecting surfaces is greater than λ/4. The stripe number is 4N when vibration amplitude dL equals Nλ. Vibrational frequency of external reflecting surface equals the frequency of feedback interference signal and has no influence on stripe number in a period. Measurement of external reflecting object based on optical feedback interference effect has measurement precision less than laser wavelength and real time direction recognition ability.
Authors: S.C. Zhang, X. Li, J. Zhang
Abstract: There were a large of the flowing through parts such as valve and slurry pump in production line of aluminum oxide. Because they were grinded and corroded by the strong alkalinity thick liquid of bauxite particles, their life was extremely shorten. So, the ZrO2/Ni60 composite coatings were manufactured by laser cladding. According to distribution state of particle phase, a set of optimum technological parameters recommended was 10.45g/min(powder feeding rate), 2.4mm/s(laser beam scan velocity), 2kW(laser power) and 60mm(defocusing amount), 5% ZrO2 (weight ratio). The M-200 abrasive tester was used to investigate the tribological behavior of the coating in strong alkaline solution (40%NaOH). As results showed, the friction and wear mechanisms of the coatings would be changed with test work condition, and the generating or dissolving of the protective passivity films on the surface of the friction pair was a dynamic state process, even as rotational speed was the high-velocity and load was the mediate load, existence could take effect in anti-wear of reinforced coating.
Authors: Bing Yan, Rui Wang
Abstract: The aim of this article is to analyze the residual stresses field in a TC4 titanium alloy blade by laser shock processing (LSP).LSP is a new surface processing technology, it uses the laser shock wave to act on the surface of the target and form residual compressive stresses field. The ABAQUS software is applied to simulate the LSP of TC4 titanium alloy blade, and the distributions of the residual stresses field are analysed.After single LSP,the maximum value of residual stress on the surface is 309 MPa.The residual stresses on the surface increase first and then decrease.The residual stresses at the depth continue decreasing with the increase of the depth.After multiple LSP,the maximum value of residual stress on the surface is increased and plastically affected depth is increased.
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