螺杆式塑料颗粒3D打印机的优化设计

发布时间：2018-06-29 01:17

本文选题：3D打印 + 塑料颗粒　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着3D打印产业的迅速发展,熔融沉积技术(FDM,Fused Deposition Modeling)已发展成为最成熟的快速成型工艺之一,其中FDM式线型塑料3D打印机凭借其打印精度高、操作灵活方便等优点得到广泛应用,但其进一步推广却受到耗材成本和材料种类所限制。本课题创新性地采用工程塑料颗粒为原料,旨在开研发出FDM式塑料颗粒3D打印机型,对降低耗材成本和拓宽原料种类具有重要研究意义。本文以螺杆式塑料颗粒3D打印机为研究对象,解决其在进料卡塞、出丝不均、打印持久稳定性差等方面的问题。基于DEM-CFD耦合模型,首先,模拟分析了在不同进料角和螺杆转速下塑料颗粒在输运过程中的运动、受力和分布情况,并将该模拟数据作为后续对优化方案的评价基准,接下来详细模拟了在圆角型进料和切向进料方案下的颗粒输运过程,重点分析了两优化方案对颗粒所受接触力和分布均匀性的影响,并进行颗粒输运过程的可视化实验对模型的准确性进行验证;然后采用欧拉两相流模型和VOF模型对原挤出头组件和新型挤出头组件进行模拟,着重分析了在自然工况、单散热工况、双散热工况和双散热工况下内置铁氟龙管时新型挤出头相对原挤出头在温度分布、熔融物料分布、流动阻力和速度矢量等方面的优化程度;最后,对优化后的机器进行样品打印实验,重点探究了打印速度、打印温度及层厚对打印质量的影响,以匹配得到最佳打印参数,通过持久性打印实验来验证优化后机器的工作稳定性。研究结果表明:在圆角型进料方案下,颗粒所受接触力值有50%~80%幅度的降低,其值大约在10~50N范围内,且颗粒线性分布特性有一定幅度的提升,而切向进料方案可使颗粒接触力值降低两个量级,在整个转速区间内均控制在0~1N范围以内,经验证模拟结果和实验数据基本吻合;与原挤出头组件相比较,自然工况下新型挤出头组件温度分布均匀性得到改善,其温差基本控制在5~10℃以内,能量有效利用率由10.25%提高至20.01%,等待加热时间和流道内最大剪切压力值均降低1/3,同时,单散热工况和双散热工况均可使喉管处温度控制在颗粒熔化温度以下,且喉管内置铁氟龙管后可使其温度进一步降低;优化后机器的最佳打印参数为:打印温度210℃、打印速度35mm/s、层厚0.10mm~0.25mm,打印质量较优化前提升一倍以上。
[Abstract]:With the rapid development of the 3D printing industry, the FDM (Fused Deposition Modeling) has developed into one of the most mature rapid prototyping processes. The FDM linear plastic 3D printer has been widely used for its advantages of high printing precision and flexible and convenient operation, but its further popularization is subject to the cost of consumables and materials. The project uses the engineering plastic particles as the raw material innovatively. The purpose of this project is to open up a type of FDM type plastic particle 3D printer, which is of great significance for reducing the cost of material consumption and widening the types of raw materials. This paper takes the screw type plastic particle 3D printer as the research object, and solves the problem of permanent stability and stability in the feed jam, the unequal out of the wire and the printing. Based on the DEM-CFD coupling model, first, the motion, force and distribution of the plastic particles in the transport process are simulated and analyzed at different feed angles and screw speeds, and the simulated data are used as the evaluation criteria for the follow-up optimization scheme. Then the scheme of the round angle feeding and tangential feeding is simulated in detail. The influence of the two optimization scheme on the contact force and distribution uniformity of the particles is emphatically analyzed, and the accuracy of the model is verified by the visualization experiment of the particle transport process. Then the Euler two phase flow model and the VOF model are used to simulate the original extruded head components and the new extruded head components. The optimization degree of the temperature distribution, the distribution of the molten material, the flow resistance and the velocity vector of the new extruded head is analyzed in the natural working condition, the single heat dissipation, the double heat transfer and the internal Teflon. Finally, the sample printing experiment is carried out to the optimized machine, and the printing speed is focused on. The influence of the printing temperature and thickness on the printing quality is matched to get the best print parameters. The stability of the optimized machine is verified by the persistence printing experiment. The results show that the contact force value of the particles is reduced by the 50%~80% range under the round angle feeding scheme, and its value is about 10~50N, and the particle is linearly distributed. There is a certain increase in sex, and the tangential feeding scheme can reduce the contact force of the particles by two orders of magnitude. It is controlled within the range of 0~1N in the whole speed range, and the simulation results are basically consistent with the experimental data. Compared with the original extruding head components, the temperature distribution uniformity of the new extruded head component in the natural working condition is improved. The temperature difference is basically controlled within 5~10 C, the effective utilization rate of energy is increased from 10.25% to 20.01%. The waiting heating time and the maximum shear pressure in the flow channel are both reduced by 1/3. At the same time, the temperature of the throat is controlled below the melting temperature of the throat, and the temperature of the pipe can be further improved. After optimization, the best printing parameters of the machine are: printing temperature 210 degrees, printing speed 35mm/s, thickness 0.10mm~0.25mm, printing quality more than doubled before optimization.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP334.8

【参考文献】