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工艺参数对管材激光弯曲成形影响规律的研究 总被引:1,自引:0,他引:1
管材激光弯曲成形是一种柔性金属塑性成形方法。将连续的激光光斑简化为一间歇跳跃的方形匀强面热源,并考虑材料性能参数与温度的相关性,建立了管材激光弯曲成形的热-机耦合有限元工艺仿真模型,对成形过程进行了数值模拟。有限元模拟结果表明:在其他条件不变的情况下,激光弯曲角度随激光功率的增大而增大,两者基本上成线性关系;弯曲角度随扫描速度的升高而减小,随光斑直径的减小而增大,但当光斑直径减小到一定程度后,弯曲角度开始减小;弯曲角度随扫描包角的增大而增大,当扫描包角为180°时,弯曲角度达到最大,弯曲角度随扫描包角的继续增大而减小;扫描次数与弯曲角度间成近似的线性关系,且第一次扫描管材产生的弯曲角度最大。 相似文献
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板料激光弯曲成形是一种利用激光成形构件的柔性成形技术。以矩形板激光单次扫描成形的过程为研究对象,通过对有限元分析软件ANSYS进行二次开发,建立了基于扫描路径的动热源模型,并系统研究了各技术参数下激光弯曲温度场的动态变化。分析发现:(1)曲线扫描准稳态过程的温度峰值要小于同工况下直线扫描情况,且持续时间短暂,温度峰值不断跳跃;(2)相同工艺参数下,随着扫描路径曲率的增大,温度峰值及加热区温度梯度均减小,当扫描路径曲率继续增大时,温度峰值及加热区温度梯度却随之增大;(3)提高激光功率,降低扫描速度以及在恒定线能量密度下增大扫描速度,均使板料温度梯度增大,而增大光斑直径,温度梯度减小。 相似文献
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F. Lambiase A. Di Ilio A. Paoletti 《The International Journal of Advanced Manufacturing Technology》2013,64(5-8):829-840
The effect of passive water cooling in laser forming of thin sheets made of AISI 304 stainless steel is experimentally investigated. Indeed, since each laser scan can produce only small bending angles, multiple laser scans are required to produce a given deformation with a significant increase of production time due to cooling between consecutive scans. Therefore, passive water cooling is tested to verify its influence on minimum time between consecutive scans (cooling time), bending angle, and surface quality. A parametric approach is involved in the investigation and main process parameters are changed among the experiments by varying laser scanning speed, laser beam power, sheet thickness, and cooling media among several levels. It was discovered that the employment of passive water cooling in laser forming of thin sheets would be beneficial since the capability to dramatically reduce the cooling time and oxidation of both irradiated and cooled surfaces. In addition, the bending angle is only marginally affected by employment of water cooling. The effect of water cooling on stress and deformations are discussed by developing a numerical model based on finite element model. 相似文献
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硅片激光弯曲成形的数值模拟与实验 总被引:1,自引:1,他引:0
介绍了一种利用脉冲激光塑性化弯曲单晶硅片的新方法。在分析和描述光脉冲时空特性的基础上,运用有限元分析软件ANSYS对硅片弯曲过程进行建模仿真,得到了脉冲激光弯曲过程中温度场与应力应变的仿真结果。对脉冲激光作用过程中温度场与应力应变的周期性瞬间变化特征进行了描述,指出了脆性材料硅片的脉冲激光弯曲机理不属于简单意义上的温度梯度机理或屈曲机理,而是二种机理共同作用的结果。通过6次扫描试验实现了对硅片的有效弯曲,弯曲角度达6.5º,仿真结果与验证性试验相符。 相似文献
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为了实现等离子电弧加热的精确弯曲成形,采用等离子电弧沿直线对1Cr18Ni9Ti不锈钢板材进行加热弯曲成形试验,并用CMOS1303uc数字相机等硬件和相关软件在等离子电弧加热弯曲成形的过程中对弯曲角度进行实时检测,实现了对成形过程的闭环控制。试验结果表明:当扫描次数较少时,板材弯曲角度随扫描次数增加近似呈线性增大;当扫描次数较多时,由于增厚效应的影响,单次扫描弯曲角度的增量会不断减小,弯曲效率明显降低。为了确保加工过程的可靠性并提高成形效率,根据加工余量的不同将成形过程分为粗、中、精三个加工阶段,各个阶段分别采用不同的工艺参数进行加工,通过弯曲角度分别为20°和30°的不锈钢薄板的成形试验验证了该方法的有效性。 相似文献
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Chelsey Pence Hua Ding Ninggang Shen Hongtao Ding 《The International Journal of Advanced Manufacturing Technology》2013,69(1-4):319-327
Laser shock bending is a sheet metal micro-forming process using shock waves induced by a nanosecond-pulsed laser. It is developed to accurately bend, shape, precision align, or repair micro-components with bending angles less than 10°. Negative bending angle (away from laser beam) can be achieved with the high-energy pulsed laser, despite the conventional positive laser bending mechanism. In this research, various experimental and numerical studies on aluminum sheets are conducted to investigate the different deformation mechanism, positive or negative. The experiments are conducted with the sheet thickness varying from 0.25 to 1.75 mm and laser pulse energy of 0.2 to 0.5 J. A critical thickness threshold of 0.7-0.88 mm is found that the transition of positive–negative bending mechanism occurs. A statistic regression analysis is developed to determine the bending angle as a function of laser process parameters for positive bending cases. 相似文献
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NUMERICAL SIMULATION FOR LASER BENDING OF SHEET METAL 总被引:4,自引:0,他引:4
0INTRODUCTIONLaserbendingofsheetmetalisanewflexibleformingtechnologyinrecentyears,whichdependsononlynonuniformheatingbutnot... 相似文献
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Y.-F. Tzeng F.-C. Chen 《The International Journal of Advanced Manufacturing Technology》2001,18(9):641-647
The paper presents an analysis of the influences of the dominant parameters of the pulsed Nd:YAG laser seam welding process
on the static behaviour of the welds. These parameters include average peak power density (APPD), mean laser power, traverse
speeds, pulse duration, and pulse shapes. Three typical temporal pulse types – ramp-up, ramp-down, and "rectangu-lar" power
pulses were used in this study. Laser seam welds were produced in 0.7 mm thick electrogalvanised steel sheets.
A number of destructive tests of pulsed Nd:YAG laser welded zinc-coated steel sheet have been carried out to characterise
the static properties of welds including hardness, bending strength, and ductility. An experimental study of acceptable welds
revealed that the hardness was affected only by the traverse speed. The bend strength was increased with decreas-ing travel
speed and increasing pulsed laser parameters. It was found that the operating parameters have no effect on the tensile strengths
of the welds. 相似文献
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Process simulation and optimization of laser tube bending 总被引:1,自引:1,他引:0
Yanjin Guan Guiping Yuan Sheng Sun Guoqun Zhao 《The International Journal of Advanced Manufacturing Technology》2013,65(1-4):333-342
A 3D thermomechanical finite element analysis model for laser tube bending is developed based on the software MSC/Marc. The processes of single- and multi-scan are analyzed numerically. The gradient and development of the temperature between the laser scanning side and the nonscanning side leads to the changing complexity of the stress and strain. Consequently, the length of the laser scanning side becomes shorter than that of nonscanning side after cooling. The length difference between both sides makes the tube produce the bending angle. The relationship between the number of scans and the bending angle is about in direct ratio. The bending angle induced by the first irradiated time is largest. Meanwhile, the finite element simulation is integrated with the genetic algorithm. Aiming at different process demands, corresponding objective functions are established. Laser power, beam diameter, scanning velocity, and scanning wrap angle are regarded as design variables. Process optimizations of maximum angle bending and fixed angle bending after single laser scan are realized. Groups of optimized process parameters can be obtained according to different optimization objectives. The bending angle can approach to the maximum when the laser power, spot diameter, scanning velocity, and scanning wrap angle are 381.24 W, 3.37 mm, 16.34 mm/s, and 123.1°, respectively. When the laser power, spot diameter and scanning velocity are 426.12 W, 4.9 mm, 14.31 mm/s respectively, a fixed angle bending can be achieved. 相似文献
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Research on the fabricating quality optimization of the overhanging surface in SLM process 总被引:1,自引:0,他引:1
Di Wang Yongqiang Yang Ziheng Yi Xubin Su 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1471-1484
Overhanging surface is inherent geometric restraint during selective laser melting (SLM), which is suitable for various complex parts fabrication. In order to improve the fabricating quality of overhanging surface, a series of experiments were designed to investigate the effects of inclined angle, scanning speed, laser power, accumulated residual stress, and scanning vector length on overhanging surface fabrication. Analysis found that overhanging surface would warp easier when the inclined angle and the scanning speed became smaller and the warping trend will be larger as the laser power became larger. The relationships of laser power, scanning speed, and the critical inclined angle were mutual restraint, that is, larger inclined angle will be designed when the laser power becomes larger and scanning speed gets smaller, or vice versa: the selection of the fabricating parameters will be determined by established inclined angle of the overhanging surface. More serious warp would happen as the processing layers increased as a result of residual stress accumulation, and it was found that longer scanning vector were more helpful to stress accumulation, leading to more serious warp than shorter vector. At last, two effective methods were adopted to optimize overhanging surface fabrication, including adjusting part orientation to improve the inclined angle at the key position, and controlling regional parameters to reduce energy input. Above two ways were adopted to manufacture complex parts with typical overhanging surface, the results proved that adjusting part orientation and controlling regional parameters were effective ways to improve the fabricating quality of overhanging surface. In this study, the basis for building overhanging surface by SLM was provided from the view of process and design, and the preliminary solutions were proposed to manufacture complex metal parts with lower risk. 相似文献
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Yonghao Luo Qingxuan Meng Wenji Xu Renke Kang Dongming Guo 《Machining Science and Technology》2016,20(1):44-61
To study the regular pattern of vapor-to-melt ratio in laser cutting sheet metal, a physical model of vapor-to-melt ratio is developed to demonstrate the material remove forms of vaporization-melt in cutting area and the state of energy and mass flow in the molten layer. Variation of vapor-to-melt ratio with laser power and cutting velocity is obtained by laser cutting of 6063 aluminum alloy sheet. The 0.5-mm sheet thickness is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of cut radius. Observation on the cut samples with different parameters (65 W, 85 W, 105 W varied with laser power increasing, and 2.2 mm/s, 2.0 mm/s, 1.8 mm/s with decreasing of beam cutting speed) and the calculations show that vapor-to-melt ratio increases (0.595–1.995, 0.672–2.631, 0.787–4.171) with laser power (65 W–110 W) and decreases with cutting velocity (1.8 mm/s–2.4 mm/s). At the same time, the laser cutting quality increases with vapor-to-melt ratio and the decrease with thickness of residual molten layer. The results show good agreement between vapor-to-melt ratio model and experiments. The analysis verifies that this model is feasible and it makes contribution to laser precision cutting. 相似文献
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The effect of continuous and pulsed beam modes on cut path deviation in diode laser cutting of glass
Salman Nisar Lin Li Mohammad A. Sheikh Andrew J. Pinkerton 《The International Journal of Advanced Manufacturing Technology》2010,49(1-4):167-175
During laser cleaving of brittle materials, with the controlled fracture technique, thermal stresses are generated which induce the crack and extend it along the cutting path, subsequently causing material separation. One of the problems in laser cutting of glass with this technique is the cut path deviation at the leading and the trailing edges of the glass sheet. Previous work with a continuous beam diode laser has shown the deviation to be partly due the high magnitudes of thermal stresses generated near the edges of the sheet. This paper reports on the effects of using a pulsed diode laser to cut soda lime glass. The effect of pulse parameters and cutting speed on the quality output variables such as cut deviation angle and surface finish are studied. Finite element modelling is also used to simulate the effects of the moving beam on stress generations to facilitate the understanding of the process mechanisms, and the results are compared with the experimental data. This work shows how to minimise the cut path deviation at the edges by reducing thermal stresses using optimum pulsed diode laser parameters and providing additional flexibility to the process. 相似文献
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板料激光弯曲成形是一种利用激光成形工件的柔性成形技术。研究激光成形过程中板料变形与扫描路径之间的关系对该技术的应用尤为重要。文章以板料激光扫描成形过程为研究对象,对激光曲线扫描中较为普遍的正弦路径进行了有限元模拟分析。结果表明,在相同工艺参数下,正弦扫描时,光斑在板料边缘停留时间相对较长,温度峰值攀升更为迅速;由于板料成形中只受热应力作用,变形区域的形状、大小与扫描路径有关。由于约束的影响,正弦扫描成形时,板料加热区表现为一个半径较大的圆弧状区域,并且由于板料中间部位受到的刚端抑制作用相对较大,使两端产生翘曲。随着弦高的减小,翘曲现象减轻,渐呈准直线。 相似文献