基于分区变层厚的熔融沉积成型技术研究

发布时间：2018-01-24 07:36

本文关键词： 熔融沉积成型分层方向分区变层厚成型成型质量　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：制造业全球化竞争的不断加剧以及用户个性化的需求体验,迫使制造企业不仅要降低生产成本、保证产品质量,而且要以更短的时间满足用户个性化的需求。快速成型技术凭借其新型的制造方法、快速的产品制造速度缩短了产品交货期,降低了制造成本,提高了企业对市场的快速反应能力。在快速成型技术的多种工艺中,熔融沉积成型技术(FDM)是目前应用最为广泛的工艺之一,但是其成型精度和效率较低,成型精度和效率之间的矛盾显著。本文提出了FDM分区变层厚的成型方法,分别从分层方向和分层厚度的角度实现了FDM成型精度与效率的协同优化。基于零件分层方向对成型精度和效率的影响分析,建立了以体积误差最小、工件在分层方向上的高度最小以及支撑体积最小为目标的FDM分层方向优化模型；设计了基于非支配排序遗传算法的智能求解算法,通过对模型的优化计算得到零件分层方向的Pareto解集,实现了FDM零件分层方向的智能优化；最后通过实例验证了所建模型的正确性与算法的有效性。分层厚度是FDM中最为重要的工艺参数,它直接影响成型精度和效率。提出了FDM分区变层厚的成型方法：轮廓层选用较小的层厚以保证工件的表面质量；填充层选用较大层厚保证工件的成型效率。通过实验研究分区变层厚成型方法对成型精度、效率以及工件强度的影响规律,结果表明：分区变层厚成型方法可以在保证工件成型效率的前提下提高其表面质量。应用ANSYS“生死单元”功能模拟了FDM的成型过程。首先进行温度场分析；随后以温度场的结果作为载荷进行应力场分析。通过对FDM过程进行热力耦合分析,得到了不同节点的温度、温度梯度、应力随时间的变化趋势,以及成型最后时刻工件的变形情况,结果表明：由于分层成型的特点,应力主要集中在xy方向上,分区变层厚成型方法下的工件变形略大于传统的偏置扫描方式下的变形。分层方向优化以及分区变层厚成型方法的研究,为FDM成型工艺参数的选择提供了依据,对于实现FDM成型精度和成型效率的协同优化具有重要意义。
[Abstract]:With the increasing global competition of manufacturing industry and the individualized demand experience of users, manufacturing enterprises must not only reduce the cost of production, but also ensure the quality of products. Rapid prototyping technology with its new manufacturing methods, rapid product manufacturing speed shortened product delivery time, reduce manufacturing costs. The technology of melt deposition forming (FDM) is one of the most widely used technologies in the field of rapid prototyping. However, the forming accuracy and efficiency are low, and the contradiction between the forming accuracy and efficiency is obvious. In this paper, a new method of FDM zonal variable layer thickness forming is proposed. Based on the analysis of the influence of the delamination direction on the forming accuracy and efficiency, the minimum volume error is established. The FDM layered direction optimization model with the minimum height of the workpiece in the delamination direction and the minimum supporting volume; An intelligent solution algorithm based on the undominated sorting genetic algorithm is designed. The Pareto solution set of the part delamination direction is obtained through the optimization calculation of the model, and the intelligent optimization of the FDM part delamination direction is realized. Finally, an example is given to verify the correctness of the model and the validity of the algorithm. Delamination thickness is the most important process parameter in FDM. It directly affects the forming accuracy and efficiency. The forming method of FDM zonal variable layer thickness is put forward: the contour layer is selected with smaller layer thickness to ensure the surface quality of the workpiece; The filling layer is selected to ensure the forming efficiency of the workpiece. Through experiments, the influence of the zone variable layer thickness forming method on the forming accuracy, efficiency and workpiece strength is studied. The results show that the surface quality of the workpiece can be improved by using the zonal variable layer thickness forming method on the premise of ensuring the forming efficiency of the workpiece. ANSYS "birth and death Unit" is applied. The function simulates the forming process of FDM. Firstly, the temperature field is analyzed. Then the results of the temperature field are used as the load to analyze the stress field. Through the thermodynamic coupling analysis of the FDM process, the variation trend of temperature, temperature gradient and stress with time of different nodes is obtained. The results show that the stress is mainly concentrated in the XY direction because of the characteristics of delamination. The deformation of the workpiece under the zonal variable layer thickness forming method is slightly larger than that of the traditional offset scanning method. The research on the delamination direction optimization and the zonal variable layer thickness forming method. It provides a basis for the selection of FDM forming process parameters and is of great significance to realize the collaborative optimization of FDM forming precision and forming efficiency.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH16

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