共查询到17条相似文献,搜索用时 156 毫秒
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《光学技术》2020,(1)
根据激光熔覆的温度场理论,利用ANSYS有限元模拟软件,模拟了多道熔覆镍基合金上表面的温度场,重点研究了激光道次间的停顿时间对激光熔覆镍基合金温度场的影响。模拟在不同停顿时间条件下的激光熔覆镍基合金的温度场,得到每一道初始位置上表面的最高温度值,以及激光基底和熔覆层交界处不同位置的温度和温度梯度值。模拟结果表明,在多道熔覆的过程中,道次间停顿1.5s对比无停顿和停顿1s时熔覆效果好,并做了相应的实验。实验结果表明,道次间停顿1.5s时,熔池深度变小,熔覆的表面平整度较好,熔覆质量较高。数值模拟和实验一致性较好,模拟和实验结果都表明,停顿时间对多道熔覆镍基合金温度场的影响较大,研究成果对激光多道熔覆镍基合金选择合适的工艺参数、降低温度梯度、提高多道次激光熔覆质量具有重要意义。 相似文献
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激光熔覆中金属粉末粒子与激光相互作用模型 总被引:4,自引:1,他引:3
为了对同轴激光熔覆过程中运动的金属粉末粒子的速度和温度进行理论分析,并研究各工艺参量的影响,建立了运动中金属粉末粒子的运动模型和热模型.模拟结果表明,粉嘴几何尺寸、粒子直径以及气/粉两相流初始速度是影响粒子运动行为的重要因素;粉嘴几何尺寸、激光焦点位置、激光发散角、激光功率、粒子直径以及气/粉两相流初始速度是影响粒子热行为的重要因素.在相同的工艺参量下(粉嘴出口内径r=2 mm,粉嘴倾角α=60°,初始气流速度v0=0.8 m/s),基于数字粒子图像测速(DPIV)技术,对316L不锈钢粉末粒子运动模型进行了实验验证.结果表明,运动理论模型是可靠的.该模型是掌握同轴激光熔覆过程中金属粉末粒子运动行为的有效工具;同时,热模型也是分析粉末粒子温度随不同参量变化的重要工具. 相似文献
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在激光烧结石墨烯增强铜基复合材料的过程中,了解瞬时温度场分布对优化工艺参数、控制烧结质量有重要作用。建立了激光烧结预涂在42CrMo基板上的石墨烯铜的混合粉末的有限元模型。研究了激光烧结过程温度场分布,熔池的几何参数以及烧结层与基体的冶金结合宽度。为了验证模拟结果,使用与模拟相同的参数进行了单道激光烧结的实验。研究表明,热传导、热辐射和相变潜热在激光烧结过程的温度场分布中起重要作用。实验结果与模拟结果较为一致。所以可以依据模拟结果预测实验的温度场分布和熔池几何参数,同时也可以据此优化激光烧结参数。 相似文献
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激光熔覆中球形粒子对激光散射强度的研究 总被引:1,自引:1,他引:0
为了研究同轴激光熔覆过程中球形粉末粒子和激光的相互作用,为激光熔覆中激光器和粒子的选择提供一定的理论依据,在进行了一定假设的前提下,应用米氏(Mie)散射理论建立了激光被球形粉末粒子散射的物理模型,应用Mathematica数学软件绘制出了在不同粒子半径和不同激光波长情况下,激光被球形粉末粒子散射后的强度分布图,并对模拟结果进行了分析.研究结果显示:金属粉末粒子的半径和激光的波长是影响激光散射强度分布的重要因素.结果表明:当光学常数q≤30的时候,散射光强在偏离传播方向20.以外还有一个次极大值,且次极大值占总散射光强比例较大,不利于熔池的形成;当光学常数q≥30的时候,散射后的光强主要集中在偏离传播方向5.~6.的小范围内,且在此范围内的散射强度很高,有利于提高激光熔覆效率. 相似文献
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数值模拟研究了高速气流作用下激光加热金属平板温度场。流体控制方程为三维雷诺平均Navier-Stokes方程,固体控制方程为能量方程,湍流粘性系数求解使用k-ε两方程模型。采用流固耦合计算方法,使用两相流模型模拟气流对烧蚀物的剥蚀,较完整地模拟了激光辐照金属材料的物理变化过程,计算得到了不同气流速度下金属平板的温度分布以及烧蚀形貌。分别使用两相流方法和动网格方法对高速气流作用下激光对金属板的烧蚀效应进行了计算,结果表明,两相流方法与动网格方法都能较好地模拟高速气流作用下激光加热金属平板的温度响应,由于两相流方法能够较全面地模拟对流换热、熔化与凝固过程以及金属液体在气流冲刷下的动力学过程,因此能获得比动网格方法更为合理的物理图像。 相似文献
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基于ANSYS的脉冲激光辐照石英玻璃的温度场数值模拟 总被引:2,自引:0,他引:2
采用有限元仿真软件ANSYS 12.0对脉冲功率激光辐照石英玻璃建立了热力学模型,对其表面温度场进行了数值模拟,得到了在不同激光功率密度下的瞬态温度场分布,并对模拟结果进行了分析和研究,为激光辐照石英玻璃实验提供依据. 相似文献
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Effects of powder concentration distribution on fabrication of thin-wall parts in coaxial laser cladding 总被引:1,自引:0,他引:1
In this paper, model of effects of powder concentration distribution on fabrication of thin-wall parts in coaxial laser cladding was developed. There exists relationship between powder concentration distribution and power density distribution, which affects fabrication of thin-wall parts in coaxial laser cladding. Changes in powder concentration distribution lead to changes in wall thickness and wall growing rate. Fluctuation of powder feed rate deteriorates the growing wall in laser cladding. Deviation of the powder flow stream makes the powder concentration distribution, the thermal flux density and consequently the molten pool not symmetrical against the x-axis, resulting in irregular upper faces of the formed wall. This was verified by the results of experiment. 相似文献
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In this paper, effects of process variables on wall thickness, powder primary efficiency and speed of forming a thin metallic wall in single-pass coaxial laser cladding are investigated, and some resolution models are established and testified experimentally. With some assumptions, each of wall thickness, powder primary efficiency and formation speed can be defined as a function of the process variables. Wall thickness is equal to width of the molten pool created in single-pass laser cladding and determined by laser absorptivity, laser power, initial temperature, scanning speed and thermo-physical properties of clad material. Powder primary efficiency and formation speed are both dependent on an exponential function involving the ratio of melt pool width, which is decided by the process variables, to powder flow diameter. In addition, formation speed is influenced by powder feed rate. In present experiment, a 500 W continual-wave (CW) CO2 laser is used to produce thin-wall samples by single-pass coaxial laser cladding. The experimental results agree well with the calculation values despite some errors. 相似文献
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激光感应复合熔覆的稀释率分析模型及实验研究 总被引:1,自引:0,他引:1
在分析计算感应加热温度模型和激光感应复合熔覆能量作用的基础上,推导出了激光感应复合熔覆稀释率的表达式,定量反映了稀释率与激光、感应能量、材料特性和工艺参数之间的关系,并且通过实验进行了验证。研究结果表明:复合熔覆的稀释率随激光功率的增加而增大,随送粉率的增加而减小,随扫描速度的增大而减小;在其他参数恒定,感应能量增加时,稀释率显著增大。该稀释率分析模型有助于复合熔覆加工中稀释率的控制,为复合熔覆工艺参数的优化设计和熔覆层的质量控制提供了理论基础。 相似文献
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Effects of processing parameters on structure of Ni-based WC composite coatings during laser induction hybrid rapid cladding 总被引:3,自引:0,他引:3
The relationships between the processing parameters (i.e. laser specific energy, powder density, preheated temperature of substrate and types of substrate) and the structure characteristics of Ni-based WC composite coatings during laser induction hybrid rapid cladding (LIHRC) were investigated systematically. The results show that laser specific energy, cladding height and contact angle have a linear relation with powder density, as can provide the predictions of laser processing parameters according to the geometrical characteristics of a single laser track (i.e. cladding height, cladding width). Moreover, dilution of composite coating increases with the increasing of laser specific energy and the preheated temperature of substrate, while reduces with the increasing of powder density. The types of substrate also have an important effect on dilution of composite coating, as has a strong dependence on the thermophysical properties of substrate (i.e. melting point, resistivity and permeability). 相似文献
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通过分析激光熔覆过程中光束、粉末和熔池间的作用机理,建立了送粉式激光熔覆材料有效利用率的数学模型,在此基础上推导了送粉角度与工艺参数之间的定量关系式,并计算了不同送粉角度下的熔覆材料有效利用率、熔高和横截面积。结果表明,在熔覆工艺参数不变的条件下,理论计算的熔覆材料有效利用率、熔覆层高度和横截面积均随送粉角度的增加而增大,且均高于实验检测值。激光熔覆过程中,由于粉末烧损和机械损失,使熔覆材料有效利用率、熔高和横截面积随送粉角度变化出现最大值,理想送粉角度为60。 相似文献
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Prediction of clad angle in laser cladding by powder using response surface methodology and scatter search 总被引:3,自引:0,他引:3
Godfrey C. Onwubolu J.Paulo Davim Carlos Oliveira A. Cardoso 《Optics & Laser Technology》2007,39(6):1130-1134
Currently, laser cladding is an important process that allows the deposition of thick protective coatings on substrates. The article presents an experimental investigation of the influence of processing parameters on clad angle in laser cladding by powder (LCP). The clad angle is determined from the mathematical expression relating to the clad height and clad width. The cladding angle model was developed in terms of laser power, scanning speed, and powder mass flow rate by means of response surface methodology. A first-order equation covering a narrow range of the variables and a second-order equation covering a wide range of the variables are presented. An optimization technique, Scatter Search, is used to determine optimal processing parameters. The adequacy of the predictive model was tested by analysis of variance and found to be adequate. 相似文献