共查询到19条相似文献,搜索用时 171 毫秒
1.
2.
快速成型技术就是直接根据CAD模型,快速生产样件或零件的成组技术总称[1],它是先进制造技术的重要组成部分.本文主要介绍了激光选区粉末烧结(SLS)技术的原理,并结合工业生产,研究了SLS快速成型件的后处理工艺,为激光选区粉末烧结快速成型技术的进一步应用打下了良好的基础. 相似文献
3.
4.
5.
通过对激光选区烧结技术——SLS烧结成型件形状和尺寸精度的研究,分析了造成收缩变形、翘曲变形的原因,提出了改变粉末烧结材料特性,提高SLS烧结精度的方法,并通过试试验验证了该方法的可行性和实用性。 相似文献
6.
7.
选区激光烧结(SLS)快速成型中CAD模型的工艺性研究 总被引:2,自引:0,他引:2
研究分析选区激光烧结 (SLS)快速成型中 ,不同尺寸和形状零件的CAD模型建立时的工艺性 ,根据实际经验得出了一些解决问题的方法 相似文献
8.
9.
粉床的预热是激光选区烧结(SLS)加工过程中一个非常重要的环节,预热均匀性对零件的成形效率和精度有着重要影响。针对大型SLS装备(2 m×2 m),由于粉床区域面积较大,粉床全场温度均匀性难以达到要求等问题,提出了分区域预热温度控制方法,建立基于辐射能系数的数值分析模型,搭建了实验平台,以尼龙12作为试验材料,开展预热试验研究,验证了数值模型的准确性,获得了大型SLS装备的最佳预热策略。试验结果表明,以尺寸为2 m×2 m尼龙12粉床为控制对象,使全场温度差控制在5℃,满足了工艺指标要求,为实现大型SLS装备研制、成形精度控制等关键问题提供技术支撑。 相似文献
10.
激光烧结复合尼龙材料的工艺参数优化研究 总被引:1,自引:0,他引:1
研究在选择性激光烧结(SLS)过程中,复合尼龙粉末激光烧结工艺参数的优化.讨论激光功率、预热温度、扫描速度、铺粉厚度等工艺参数对制件强度的影响.采用正交试验的方法,在不同工艺参数下将复合尼龙粉末烧结成9组哑铃状试样,以强度为指标,计算出强度最好的工艺参数组合,并结合比较试件的尺寸精度得到激光烧结复合尼龙材料的最优工艺参数为:激光功率14 W,预热温度95℃,扫描速度1 400 mm/s,铺粉厚度0.1 mm. 相似文献
11.
基于零件切片的选择性激光烧结预热温度控制方法 总被引:5,自引:0,他引:5
选择性激光烧结(Selective laser sintering,SLS)系统是通过加支撑或采用人工调节预热温度的方法来减少成形件的翘曲变形,它劳动强度大、SLS材料浪费多、成形效率低,且预热温度难以精确控制。基于以上情况,提出一种新的控制方法,使预热温度能随零件断面几何形状的变化而自动调节。以华中科技大学开发的SLS设备为研究对象,验证这种新型控制方法的可行性。试验结果和实际应用表明:与原有控制方式比较,根据文中所提出的方法成形的零件表面质量、尺寸精度和形状精度等都有较大幅度改善,并且真正实现了SLS成形过程的自动化。 相似文献
12.
13.
14.
15.
将环氧树脂和固化剂按不同比例混合后摇匀,分别涂抹在SLS烧结件上,测试SLS烧结件的固化时间和固化强度;并将涂抹后的SLS烧结件放在恒温干燥箱,研究不同温度下对烧结件的影响。试验结果表明,固化剂的用量和固化环境温度对烧结件有一定影响。 相似文献
16.
Optimizing process parameters for selective laser sintering based on neural network and genetic algorithm 总被引:1,自引:0,他引:1
Wang Rong-Ji Li Xin-hua Wu Qing-ding Wang Lingling 《The International Journal of Advanced Manufacturing Technology》2009,42(11-12):1035-1042
Selective laser sintering (SLS) is an attractive rapid prototyping (RP) technology capable of manufacturing parts from a variety of materials. However, the wider application of SLS has been limited, due to their accuracy. This paper presents an optimal method to determine the best processing parameter for SLS by minimizing the shrinkage. According to the nonlinear and multitudinous processing parameter feature of SLS, the theory and the algorithms of the neural network are applied for studying SLS process parameters. The process is modeled and described by neural network based on experiment. Moreover, the optimum process parameters, such as layer thickness, hatch spacing, laser power, scanning speed, work surroundings temperature, interval time, and scanning mode are obtained by adopting the genetic algorithm based on the neural network model. The optimum process parameters will be benefit for RP users in creating RP parts with a higher level of accuracy. 相似文献
17.
Rong-Ji Wang Lingling Wang Lihua Zhao Zijian Liu 《The International Journal of Advanced Manufacturing Technology》2007,33(5-6):498-504
Shrinkage, one of the typical phenomena in the selective laser sintering (SLS) process, affects the final dimensional accuracy
of SLS products. We investigated the relationship between the shrinkage and the process parameters of SLS in order to improve
dimensional accuracy. According to the characteristic of SLS, the following process parameters are considered: layer thickness,
hatch spacing, laser power, scanning speed, temperature of working environment, interval time and scanning mode. A neural
network model on the relationship between the processing parameters and shrinkage was built on the basis of a series of experiments.
The experimental investigation results show that the neural network model is possible to be used to predict the effects of
the process parameters on the shrinkage with reasonable accuracy and to analyze the relationship between the shrinkage and
the process parameters of SLS quantitatively. So it is suitable to apply neural networks approach to study the SLS process.
This model will allow us to produce the SLS parts with the desired quality attributed by selecting the appropriate parameter
values prior the processing. This paper proposes a promising approach to improve the accuracy of the SLS part. 相似文献
18.
CUTTING TEMPERATURE MODELING BASED ON NON-UNIFORM HEAT INTENSITY AND PARTITION RATIO 总被引:1,自引:0,他引:1
The understanding of temperature distribution along the tool-chip interface is important for machining process planning and tool design. Among many temperature modeling studies, uniform heat partition ratio and/or uniform heat intensity along the interface are frequently assumed. This assumption is not true in actual machining and can lead to ill-estimated results at the presence of sticking and sliding. This paper presents a new analytical cutting temperature modeling approach that considers the combined effect of the primary and the secondary heat sources and solves the temperature rise along the tool-chip interface based on the non-uniform heat partition ratio and non-uniform heat intensity along the interface. For the chip side, the effect of the primary shear zone is modeled as a uniform moving oblique band heat source, while that of the secondary shear zone is modeled as a non-uniform moving band heat source within a semi-infinite medium. For the tool side, the effect of the secondary heat source is modeled as a non-uniform static rectangular heat source within a semi-infinite medium; and the primary heat source affects the temperature distribution on the tool side indirectly by affecting the heat partition ratio along the interface. Imaginary heat sources are considered as a result of the adiabatic boundary condition involved along the tool-chip interface and of the insulated boundary conditions along both the chip back side and the tool flank face. The temperature matching condition along the tool-chip interface leads to the solution of distributed heat partition ratio by solving a set of linear equations. The proposed model is verified based on the published experimental data of the conventional turning process and it shows both satisfactory accuracy and improved match. 相似文献
19.
Zhiyong Zhang He Yang Heng Li Zhijun Tao Dan Wang 《The International Journal of Advanced Manufacturing Technology》2014,72(9-12):1187-1203
The heat rotary draw bending of large-diameter thin-walled (LDTW) commercial pure titanium (CP-Ti) tube is a highly nonlinear thermo-mechanical coupled physical process. Developing a reliable finite element (FE) model for this process is an effective way to investigate the heat loading and the complex bending behaviors. In this study, considering the characteristics of multi-die constraints and local heating, a thermo-mechanical 3D-FE model was established for preheating and heat bending of LDTW CP-Ti tube in terms of both accuracy and efficiency. First, using the static implicit algorithm, a preheating model was developed to predict the temperature distribution of bending tools. In this model, the key issues such as the full-sized geometry modelling, thermal interaction definition, and automatic heating control were solved to increase the simulation accuracy and efficiency. Then, introducing the predictions of preheating model and using the dynamic explicit algorithm, a thermo-mechanical coupled 3D-FE model was established for the heat bending simulation via the geometry modelling simplification, temperature definition of bending tools, realization of non-uniform temperature distribution, etc. Considering the temperature history of bending tools and wall thickness changing of bent tube, the reliability of preheating model and heat bending model was verified by several experiments. The results showed that the maximum relative errors of both predicted temperature and wall thickness changing degree were less than 9 %. Based on the reliable models, the effects of preheating temperature on the temperature distribution of bending tools and wall thickness changing of tube were numerically evaluated. The established model provides the scientific basis for the prediction and control of bending qualities of the heat RDB process, and the modeling method is also of general significance to the other heat-aided forming process. 相似文献