Time filter

Source Type

LI C.,Wuhan Huagong Laser Engineering Co. | LI B.,Huazhong University of Science and Technology | WU Z.-F.,Wuhan Huagong Laser Engineering Co. | QI X.-Y.,Wuhan Huagong Laser Engineering Co. | And 3 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2017

Stitch welding of plate covered skeleton structure of Ti–6Al–4V titanium alloys has a variety of applications in aerospace vehicle manufacture. The laser stitch welding of Ti–6Al–4V titanium alloys was carried out by a 4 kW ROFIN fiber laser. Influences of laser welding parameters on the macroscopic geometry, porosity, microstructure and mechanical properties of the stitch welded seams were investigated by digital microscope, optical microscope, scanning electron microscope and universal tensile testing machine. The results showed that the three-pipe nozzle with gas flow rate larger than 5 L/min could avoid oxidization, presenting better shielding effect in comparison with the single-pipe nozzle. Porosity formation could be suppressed with the gap between plate and skeleton less than 0.1 mm, while the existing porosity can be reduced with remelting. The maximum shear strength of stitch welding joint with minimal porosity was obtained by employing laser power of 1700 W, welding speed of 1.5 m/min and defocusing distance of +8 mm. © 2017 The Nonferrous Metals Society of China


Wang X.,Huazhong University of Science and Technology | Wang A.,Huazhong University of Science and Technology | Tang H.,Wuhan Huagong Laser Engineering Co. | Xiong D.,Wuhan Huagong Laser Engineering Co. | Ye B.,Wuhan Huagong Laser Engineering Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

To improve the service life of valves used in pulp industry, Co-based coatings were produced on 304 stainless steel substrate by diode laser cladding. Effect of laser parameters on properties of coating was investigated, and wear resistance of the coating compared with that of the traditional manual surfacing at different temperatures was analyzed. The results show that higher dilution ratio lead to lower hardness and the coating produced with laser power 2000 W and scanning speed 20 mm/s has good morphology and low dilution ratio. Wear tests show that the wear mechanism is abrasiveness at 100 ℃ and 200 ℃, and adhesive wear happen at 300 ℃and 400 ℃. Besides, the wear resistance of the laser cladded coating is better than that of the manual surfacing coating at all temperatures because of dilution, coarse grain and lower hardness. © 2016, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.


Wu Y.,Huazhong University of Science and Technology | Wang A.H.,Huazhong University of Science and Technology | Zheng R.R.,Huazhong University of Science and Technology | Tang H.Q.,Wuhan Huagong Laser Engineering CO. | And 2 more authors.
Applied Surface Science | Year: 2014

Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only. © 2014 Elsevier B.V.


Dapeng Y.,Wuhan Raycus Fiber Laser Technologies Co. | Libo L.,Wuhan Raycus Fiber Laser Technologies Co. | Xiaoxu L.,Wuhan Raycus Fiber Laser Technologies Co. | Dayong M.,Wuhan HuaGong Laser Engineering Co.
Journal of Physics: Conference Series | Year: 2011

Solutions of kW continuous-wave (CW) all-fiber laser are proposed. In our solutions, master oscillator power amplifier (MOPA) configuration is applied. Output power of master oscillator is 10W, and then is amplified to 70W with 1st pre-amplifier and next scaled up to 400W. Finally, 400W fiber laser is used as a basic power unit, and 1000W all-fiber laser can be achieved by means of beam combining with large core double clad fiber (DCF) combiner. In this solution, fiber laser has good stability and reliability for dispersion coupling of pump source and inhibition of photon darkening effect in the fiber. In addition, this solution assures us realize a 1000W all-fiber laser product easily, and the cost is low.


Weng Z.,Huazhong University of Science and Technology | Wang A.,Huazhong University of Science and Technology | Wang Y.,Huazhong University of Science and Technology | Xiong D.,Wuhan Huagong Laser Engineering Co. | Tang H.,Wuhan Huagong Laser Engineering Co.
Surface and Coatings Technology | Year: 2016

In this research, repairing of V-grooves on ductile cast iron substrates has been successfully completed with diode laser cladding technique using Fe-base self-fluxing alloy powder as the cladding material. The repaired samples are free of any defects such as pores and cracks with appropriate process parameters and the V-groove bevel. The bonding interface behavior at different power levels and the effect of the V-groove bevel on the cracking sensitivity of the coatings have been investigated. Optical microscopy, scanning electron microscopy, energy dispersive microanalysis and X-ray diffraction were used to characterize the cladded layers and bonding interfaces. Microhardness of the repaired samples was evaluated after cladding. The results revealed that good bonding interface with discontinuous fusion zone can be achieved at a lower laser power. The cracking sensitivity of the cladded layer is closely related to the V-groove bevel and the V-groove with larger bevel can be repaired with no cracks and pores. The cladded layers consist of austenite and martensite while some carbides such as Cr7C3, Fe7C3 and Fe3C are formed in the bonding interface. Microhardness is rather homogeneous throughout the cladded layers and much higher than that of the substrate. © 2015 Elsevier B.V.


Hu Q.,State Grid Electric Power Research Institute of China | Wang J.,Wuhan Huagong Laser Engineering Co. | Wu X.,State Grid Electric Power Research Institute of China | Pan J.,State Grid Electric Power Research Institute of China | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2016

In order to test the anti-pollution performance of fiberglass-reinforced epoxy composite, and to provide the data for the use of power transmission, by preparing the general molding-epoxy-fiberglass composites with six different hydrophobic coatings on their surfaces, we tested the contact angle, rolling angle, wet-withstand voltage, and pollution withstand voltage of the samples. Moreover, we measured the material surface resistance and electrical properties of antifouling pollution. The results show that the composites with hydrophobic coating improve the anti-pollution performance. The performance of anti-pollution flashover room temperature vulcanized silicone rubber(PRTV) coating is the best whose contact angle is more than 120°. Compared with the composite without coating, the performance of power frequency flashover and withstand voltage increase by 20% for the the PRTV samples in the class III. After several discharge along surface flashover, the hydrophobic surface will weaken or even disappear. In the recovery of hydrophobicity, PRTV and IC701 is better than DS-02 coating. © 2016, High Voltage Engineering Editorial Department of CEPRI. All right reserved.


Li B.,Huazhong University of Science and Technology | Li B.,Wuhan Huagong Laser Engineering Co. | Zhao Z.,Huazhong University of Science and Technology | Wang C.,Huazhong University of Science and Technology | And 2 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2015

Ultraviolet emission signals and infrared emission signals and audible sound signals were collected in CO2 laser welding of 1.8 mm galvanized steel plate. The correlation and difference among three signals were compared between laser deep penetration welding and laser heat conduction welding. The transient behaviors of keyhole and plasma were also analyzed during laser penetration welding process. The results indicate that the keyhole and plasma are not always generated at the same time and the plasma is produced prior to keyhole. The plasma may appear in the heat conduction welding. Under the experimental conditions, the plasma forms after 3-4 ms of laser being irradiated on the samples, while the stable keyhole forms at about 14 ms after welding. It has been found that the power intensity used to produce the plasma is lower than that of the keyhole. ©, 2015, Harbin Research Institute of Welding. All right reserved.


Wang Z.,Huazhong University of Science and Technology | Wang Z.,Wuhan Huagong Laser Engineering Co. | He L.,Wuhan Huagong Laser Engineering Co. | Xie Y.,Huazhong University of Science and Technology | And 2 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2011

Compared with the traditionally manufacture of single mesa diode wafer which has some disadvantages such as low speed and high chipping rate of blade-sawing, laser scribing is of high yield rate because of non-contact processing. According to the properties of crystal silicon (Si), the direction of the scribing and its mechanism of Si processed by infrared (IR) laser are discussed. On the base of approximate analytical solution derived from one-dimensional heat conduction equation, the ablation depth influenced by laser power and scanning speed is calculated. 7.62 cm wafer scribed under the condition of 1064 nm pulsed fiber laser shows that chipping rate is less than 1% and eligible electrical properties attain 100%. Research shows that ablation depth can influence the chipping rate and defocusing amount can influence the electrical properties of the chip. High yield rate can be achieved by controlling the ablation depth and defocusing amount during the scribing.


Patent
Wuhan Huagong Laser Engineering Co. | Date: 2011-02-15

The present invention discloses a laser puncher for punching holes on tipping paper in a curve manner, which comprises a panel, a light guiding cylinder, a laser connected with the light guiding cylinder, a transmission system driving a piece of tipping paper to move and at least one focusing optical head and at least one driving motor is fixed on the panel, a screw shaft is connected with the driving shaft of the driving motor, a nut is connected with the screw shaft and fixedly connected with a connecting rod, the other end of which is fixedly connected with at least one moving optical cylinder, one end of which is provided with the light guiding cylinder, and the other end of which penetrates the panel to be fixedly connected with the focusing optical head, the external periphery of the moving optical cylinder is provided with an anti-rotation linear bearing, which is fixed on the panel, and the driving motor drives the focusing optical head to reciprocate back and forth via the screw shaft, the nut, the connecting rod and the moving optical cylinder. The present invention can increase the identifiability of tipping papers on which holes are punched with a laser puncher as well as the air permeability of tipping papers.

Loading Wuhan Huagong Laser Engineering Co. collaborators
Loading Wuhan Huagong Laser Engineering Co. collaborators