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覆膜砂SLS过程激光能量分布模型的建立及应用 总被引:1,自引:0,他引:1
针对具有新光束的CO2激光器,建立了铸造覆膜砂SLS过程的激光能量分布模型,在该模型中,综合考虑了新型激光光束的光强分布特点,实际扫描过程中激光与覆膜砂的相互作用,以及扫描速度对激光能量输入的影响等因素.采用Ansys对覆膜砂SLS过程的激光能量分布模型进行计算,利用热像仪对覆膜砂选择性激光烧结过程的表面温度进行测定.经对比计算结果和测温结果,模拟计算与实际测温结果吻合良好.根据模拟计算结果所确定的工艺参数,实际制造出了具有较高精度的三维实体.覆膜砂SLS过程激光能量分布模型为激光快速成形工艺的计算机分析及优化奠定了基础. 相似文献
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新的激光快速成形方法及应用 总被引:3,自引:1,他引:2
针对目前主要激光快速成形方法的优缺点,提出一种基于三维实体边界分割的激光快速成形新方法.该方法将叠层实体制造(LOM)法主要进行激光二维轮廓线扫描和选择性激光烧结(SLS)法能够加工多种覆膜粉末材料的优点有机结合,能够克服SLS法加工效率低,成形件致密度、硬度、精度和表面粗糙度等性能较低的缺点.利用自主开发的快速成形系统,采用热像仪测温与Ansys模拟激光能量输入模型相结合的方法对工艺参数进行确定,对基于三维实体边界分割激光快速成形方法进行应用研究,实现三维实体的快速成形及金属零件的快速铸造,并通过无模具快速铸造的手段获得金属齿轮铸件. 相似文献
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系统地分析了覆膜材料激光加工的原理,通过分析各参数对温度的影响,得到了温度场的计算模型,并对覆膜材料的选择性激光烧结成形温度场的分布变化进行了数值模拟计算,分析了烧结过程及热物性参数之间的变化关系。利用有限元方法对温度场进行模拟,建立合理的有限元模型,得到了烧结件的温度变化趋势,并用热电偶测温系统实测温度验证计算结果,从而可以提高制件的精度。 相似文献
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研究了激光选区烧结(SLS)成型工艺中不同工艺参数以及后续热处理工艺对超高分子量聚乙烯(UHMWPE)材料成型性能的影响。通过调整扫描间距、激光功率、扫描速度等不同工艺参数,描述了SLS成型UHMWPE零件的致密度、拉伸强度以及断裂伸长率,并对热处理前后的SLS成型UHMWPE零件的力学性能进行了比较。结果显示,致密度、拉伸强度、断裂伸长率总体上与激光功率呈正相关关系,与扫描间距、扫描速度呈负相关关系。经热处理后,SLS成型UHMWPE零件的力学性能有明显提高,致密度达到95.12%,抗拉强度达到24.08 MPa,断裂伸长率达到334.82 MPa。实验结果表明:SLS成型UHMWPE零件与模塑成型UHMWPE零件性能尚有差距,仅优化成型工艺不足以得到理想性能,但经热处理后,零件性能基本满足使用要求。 相似文献
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The laser homogenizing equipment was devised using the ring scanning principle. Its working principle is explained. A laser
scanning ring facula is obtained when the laser beam goes through the equipment’s optical system rotating with high-frequency.
The scanning ring facula’s mathematic model is established based on the temperature field’s superposing principle. The ring
facula’s light intensity distribution and temperature distribution characteristics are achieved by simulating its temperature
field. By studying the effect of parameters on the temperature field, the best parameters can be found. Results show that
favorable temperature distribution characteristics can be attained by choosing appropriate parameters, and even the thermal
effect can be realized by utilizing the circumference power compensating for the heat exchange lost in the horizontal direction.
The uniform hardness layer and better process quality can be attained using the ring facula optimized for metal laser heat
treatment. 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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直角坐标激光直写的动态曝光模型 总被引:2,自引:0,他引:2
在兼顾胶层的光吸收特性、直写光束的高斯分布特征以及直写光束与胶层相对运动的情况下,建立了直角坐标激光直写的动态曝光模型以有效预测线条的线宽和侧壁角.仿真实验表明:以恒值高斯光强曝光时,该模型与等效仿真条件下的Dill曝光模型仿真结果完全一致.进一步证明了该模型的有效性和正确性,解决了目前在激光直写中存在的只能预测线宽或在忽略光刻胶吸收作用的情况下粗略估计直写线条轮廓的问题.同时,基于该模型分别分析了直写光功率和直写速度对线条轮廓的影响机理,为优化激光直写工艺的加工参量提供了一种有效的分析途径. 相似文献
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FU Jianzhong XIANG Hengfu CHEN Zichen School of Mechanical Engineering Zhejiang University Hangzhou China 《机械工程学报(英文版)》2006,19(4):570-573
The use of a CO2 laser system for fabrication of microfluidic chip on polymethyl methacrylate (PMMA) is presented to reduce fabrication cost and time of chip. The grooving process of the laser system and a model for the depth of microchannels are investigated. The relations between the depth of laser-cut channels and the laser beam power, velocity or the number of passes of the beam along the same channel are evaluated. In the experiments, the laser beam power varies from 0 to 50 W, the laser beam scanning velocity varies from 0 to 1 000 mm/s and the passes vary in the range of 1 to 10 times. Based on the principle of conservation of energy, the influence of the laser beam velocity, the laser power and the number of groove passes are examined. Considering the grooving interval energy loss, a modified mathematical model has been obtained and experimental data show good agreement with the theoretical model. This approach provides a simple way of predicting groove depths. The system provides a cost alternative of the other methods and it is especially useful on research work of microfluidic prototyping due to the short cycle time of production. 相似文献
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Stereolithography is one of the rapid prototyping processes which uses a photopolymer as the raw material to build prototypes. The photopolymer absorbs energy by selective laser exposure. The curing effect starts when the absorbing energy exceeds a critical value, and the process is called photopolymerisation. The photopolymerisation changes the phase from liquid to solid. The cured volume can expand and then shrink on cooling. The process parameters such as the scanning speed, scanning path, scanning pitch, and the slicing thickness, lead to different shrinkage and curl distortion, so, the photopolymerisation process is a dynamic material behaviour. In this study, a dynamic finite element simulation code has been developed to simulate the photopolymerisation process. The simulated result for a suspended beam which corresponds to the process parameters shows that a short raster causes less curl distortion than a long raster. The experimental result agrees very well with the simulated result. 相似文献
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Magnus Rohde Christine Markert Wilhelm Pfleging 《The International Journal of Advanced Manufacturing Technology》2010,50(1-4):207-215
Experimental and numerical studies were conducted on the effects of the laser beam pulse shaping in the time domain on the quality of the welding seam in laser micro-welded AlMg3 with a thickness of 0.2 mm and 1 mm thick AlMg4.5 Mg foils, respectively. The pulse shaping was realized by a time sequence of three different rectangular pulses with different duration and power level. The first pulse was used to pre-heat the sample, welding occurred with the second pulse and the third pulse controlled the melt pool behavior. The power level and the duration of the single pulses were varied systematically and the resulting microstructure was analyzed by scanning electron microscope. The experiments were accompanied by numerical simulations based on a finite volume model which considers the transient heat flow, melt convection and the evolution of a gas capillary during the deep penetration welding process. 相似文献
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Pedro Fernández J. Carlos Rico Braulio J. Álvarez Gonzalo Valiño Sabino Mateos 《The International Journal of Advanced Manufacturing Technology》2008,39(7-8):699-715
This paper presents a methodology to develop an automatic process planning system applied for scanning parts with free-form surfaces by using a laser stripe system mounted on a coordinate measuring machine (CMM). The part has been modelled using a STL format that permits the automatic recognition of any part surface. The valid orientations of the scanning device are obtained in order to guarantee the visibility of the zone to be scanned and also to be compatible with the constraints imposed by the process. With the aim to speed up the calculation of valid orientations, we apply different methods like space partitioning techniques base on kd-tree as well as back-face culling algorithms. Once the space occupied by the part is partitioned in regions, recursive ray traversal algorithms are used in order to exclusively check for intersection the part triangles of the STL model that can potentially be traversed by each laser beam direction. In order to reduce the scanning time related to laser orientation changes, part triangles must be classified into a set of clusters based on their common visibility orientations. Finally, the scanning paths for each cluster are generated as well as the joining paths between them by taking into consideration depth of field and laser beam width. 相似文献