【作者】 彭昌吻；

【导师】 曾晓雁； 王泽敏；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2009， 硕士

【摘要】 选择性激光熔化技术(Selective Laser Melting)是一种新型的快速成型技术,其成形工艺简单,可直接制成终端高致密度金属产品。SLM技术是近年来才发展起来的技术,国内外对成形零部件宏观质量方面的研究报道较少,因此,开展对SLM技术制造成形零部件宏观质量方面的研究具有重要意义。首先,本文依据选择性激光熔化技术的特点,从扫描线的单道熔覆高度和宽度出发,分别研究了激光功率、扫描速度、能量密度对单道熔覆高度和宽度的影响规律。并以此为基础,采用SLM方法在不同工艺参数下制造出理论高度为10mm的薄壁墙,并对薄壁墙高度方向的成形精度进行了研究,结果表明成形精度在±0.1mm的参数为:激光功率170W左右,扫描速度36~48m/min,切片层厚0.2~0.35mm。在此工艺参数范围内选取合适参数,制造出尺寸为27×12×10mm3的复杂结构零件,其平均误差达±0.172mm,偏差主要集中在0.002mm处。然后,通过正交实验的方法,研究了选择性激光熔化成型件时激光工艺参数对表面粗糙度的影响规律,结果表明,激光功率为主要影响因素。获得最佳表面粗糙度的工艺参数为:激光功率143W,扫描速度12m/min,搭接率为0.5。通过改变切片层厚和倾斜角度α,研究了选择性激光成型件侧表面的粗糙度,结果表明成型零部件的侧面粗糙度与切片层厚的大小成正比,与倾斜角度的大小成反比。当切片厚度为0.2mm,倾斜角度为90°时,零件侧面的粗糙度最小。采用优化的工艺参数,制造出了尺寸为10×10×10mm3金属立方体,其致密度达到了96.8%以上。最后,对不同切片层厚下薄壁的极限倾斜角度进行了研究,结果表明切片层厚为0.2mm时,选择性激光熔化成型的极限倾斜角度可以达到30~35°,当零件侧面倾斜角度在这个范围内变化时不用添加支撑即可直接成形。更多还原

【Abstract】 Selective Laser Melting (SLM) is a new kind of rapid processing technology which is simple molding and can directly produce the terminal metal productions. Because of the recent development of SLM technology, the reports about the macro-quality of molding parts are few, which retard the further study of the technology. As a result, the developing research based on SLM of molding parts’macro-quality is very important.Firstly, this thesis studies the regulation of the height and width of single cladding, which are affected by the laser power, the laser scan velocity and the energy density. Based on the former theory, a further experiment analyses the changing regulation of the measurement precision by fabricating a wall of 10mm height. The research finds out that the parameter range is laser power 170W, scan velocity is from 36m/min to 48 m/min and the thickness of slice is from 0.2mm to 0.35mm when the molding precisions are±0.1mm. In the scope of technique parameters, the researchers successfully select the proper parameters to produce a complex structure with the size of 27×12×10mm3 in high precision, whose average error reaches±0.172mm and the deviation concentrates at 0.002mm.Then, based on the method of the design of the orthogonal experiment, the thesis investigates the roughness of the surface of molding parts and finds that the laser power is the main factor. By optimizing parameters the researchers finds out that when laser power reaches 143 W, the scan velocity is 12m/min and the overlap is 0.5 would be the best. Furthermore, through the method of changing the thickness of the slice and tilt angleα, the thesis researches the roughness of the side face of the molding parts. From the research, the roughness of the side face is direct proportional to the height of the slice and is inversely proportional to tilt angle. When the thickness of the slice reaches to 0.2mm and the tilt angle is 90°, the roughness of the side face achieves the minimum.Moreover, a 10×10×10mm3 metal cubic is made by technique parameter optimization. Through measurement and calculation, the density of the metal cube reaches more than 96.8%.Finally, the thesis research the ultimate tilt angle of the thin-sheets in different thickness of slice, and finds out that when the thickness of the slice is 0.2mm, the tilt angle can reach 30~35°. When the change of the tilt angle of the side face stays in this scope, it is not necessary to add a sustentation, but molding directly.更多还原