均匀金属微滴气动按需喷射行为及表面形貌控制研究

发布时间：2018-03-06 21:39

本文选题：快速成型　切入点：金属熔滴　出处：《西北工业大学》2016年博士论文　论文类型：学位论文

【摘要】：均匀金属微滴喷射成形技术作为一种新型的金属零件快速成型技术,近年来受到研究者越来越多的关注。成型过程中,金属坯料被加热到熔融态后在驱动压力的作用下流出喷嘴形成均匀微滴,随后通过协调控制微滴的按需喷射与基板的运动,使微滴根据需要沉积到特定位置,如此逐点、逐层地堆积成型出三维结构。该技术无需昂贵的设备、特殊的模具和专门处理的原材料,具有工艺流程简单、生产成本低、成型制件性能好等优点,在微小金属零件快速成型、柔性电路打印、微电子封装等领域都具有广阔的应用前景。然而,该技术涉及均匀金属微滴的产生、沉积凝固、搭接成型等过程,成型质量受微滴尺寸均匀性、熔合状态、搭接形貌等诸多因素的综合影响,将其直接应用于微小金属零件的实际生产,还需突破均匀金属微滴稳定喷射、制件表面形貌优化控制等关键技术。基于此,本文采用理论分析与试验相结合的方法,研究了气动按需式微滴喷射行为,探索了微滴稳定喷射和尺寸细化的方法,实现了微小熔滴的稳定制备;首次确立了金属微滴喷射成形制件表面形貌评价指标与表征模型,系统研究工艺参数对表面形貌的影响规律,以期获得制件表面形貌优化控制策略,达到推动微滴喷射成形技术工程化应用之目的。本文的主要研究内容如下:设计开发了均匀金属微滴喷射成形试验系统,包括金属熔炼喷射子系统、微滴喷射与平台运动联合控制子系统、成型过程监控子系统等。通过对熔炼装置和微滴喷射装置的改进,实现了不同金属熔液的稳定喷射;建立数据采集、视频监控子系统,实现了熔滴温度、基板温度等工艺参数的测量和喷射沉积行为的观察,为后续深入研究微滴喷射成形技术奠定了硬件基础。采用试验方法研究了腔内脉冲气压波形随供给压力、脉冲宽度等工艺参数变化的规律,获得了脉冲气压波形的控制方法;建立了单路进气微滴喷射装置仿真模型,研究了工艺参数对微滴喷射行为的影响规律。依据仿真结果,确立了均匀金属微滴稳定喷射参数控制策略,并将其用于指导试验,获得了金属微滴稳定喷射参数范围。从理论上探明了单路进气微滴喷射装置由于受到射流断裂方式的限制而无法产生小于喷孔直径微滴的原因,提出并开发了双路进气微滴喷射装置,通过仿真方法,研究了双路进气喷射装置的结构参数对金属微滴尺寸的影响规律。研究结果表明喷孔高径比、进气孔与喷孔间距对微滴尺寸具有重要影响。在理论研究指导下,优化双路进气喷射装置结构参数,最终实现了小于喷孔直径的金属微滴的喷射,为改善制件表面形貌提供了有效途径。通过分析金属微滴喷射成形工艺和制件表面形成过程,首次提出微滴喷射成形制件表面形貌评价指标;研究了熔滴温度、基板温度等工艺参数对单颗熔滴沉积行为和沉积形貌的影响规律,确立了圆弧模型为单颗熔滴沉积形貌最佳表征模型;并在此基础上进一步建立了成型制件表面形貌表征模型,可初步预测不同工艺参数下表面形貌的各项评价指标。采用试验方法系统研究了扫描步距、层间偏距、熔滴温度、基板温度、沉积高度等工艺参数对制件顶面形貌和侧面形貌的影响规律,获得了各工艺参数的控制方法及合适的取值范围。采用优选参数成型出具有良好表面质量的平面制件和方框制件,验证了工艺参数的有效性,为均匀金属微滴喷射成形技术进一步在微小复杂零件成型领域的应用奠定了基础。
[Abstract]:Uniform metal droplet spray forming technology is a new type of metal parts rapid prototyping technology, has attracted more and more researchers attention in recent years. During the forming process, the metal is heated to melt after the driving pressure out of the nozzles to form uniform droplets, then through the coordinated control of micro droplets on-demand jet with the movement of the substrate, the droplet deposition according to the need to a specific location, so point layer stacking forming a three-dimensional structure. The technology without expensive equipment, special tooling and special processing of raw materials, process flow with Cheng Jiandan, the production cost is low, the advantages of molding performance, in the fast micro molding metal parts, flexible printing circuit, has the broad application prospect of microelectronics packaging and other fields. However, the technique involves the generation of uniform metal droplet deposition, solidification, lapped into type, molding quality The amount of the droplet size uniformity, fusion state, comprehensive influence of overlapping morphology and many other factors, the actual production to be directly applied to the micro metal parts, also need to break the uniform metal droplet spray stability, the key technology of parts surface topography optimization control. Based on this method, this paper combines the theory analysis and test the research on the pneumatic on-demand micro droplet ejection behavior, explore the method of droplet size and spray stable refinement, to achieve a stable system of micro droplet; for the first time established a droplet spray forming workpiece surface morphology evaluation index and characterization model, the influence of process parameters on surface morphology. In order to obtain the workpiece surface topography optimization control strategy, to promote the micro droplet forming technology in engineering application. The main contents of this paper are as follows: the design and development of uniform metal droplet spray forming Test system, including the metal melting injection system, micro droplet jetting and platform motion joint control subsystem, process monitoring subsystem. Through the melting device and micro droplet jetting device is improved, to achieve a different molten metal jet stability; establishment of data acquisition, video monitoring system, realize the droplet the temperature measuring process parameters such as substrate temperature and deposition behavior observation, laid the hardware foundation for the further studies on droplet spray forming technology. The intracavity pulse pressure waveform with the supply pressure by adopting the test method, change width and other parameters of the regular pulse control method of pulse pressure waveform is obtained; a single the intake path micro droplet injector simulation model, studied the influence of process parameters on the droplet ejection behavior. According to the simulation results, the establishment of the uniform metal droplet spray parameter stability The control strategy, which can be used to guide the test, obtained stable droplet injection parameters. Theoretically proved the single inlet droplet jet apparatus due to jet fracture limit cannot be less than the diameter of nozzle hole droplet, proposed and developed dual inlet droplet ejection device, through the simulation method, the influence law of structure parameters of dual inlet injection device of metal droplet size. The results show that the orifice aspect ratio, inlet and nozzle spacing has important influence on the droplet size. In the direction of the theory, optimization of dual inlet injection device structure parameters, finally realizes the injection less than the orifice diameter of droplet, provides an effective way to improve the surface morphology of parts. Through the analysis of metal micro droplet formation process and surface parts forming process, first proposed the micro droplet jetting forming system The surface morphology evaluation index; droplet temperature research, influence of process parameters on the substrate temperature of single droplet deposition behavior and morphology, established the arc model for the single droplet deposition morphology and characterization of the best model; on this basis to further establish the molding surface morphology characterization model, evaluation indexes can be predicted under different process parameters. The surface morphology was studied by scanning step test method, interlayer offset, droplet temperature, substrate temperature, influence of deposition parameters on the height of the top surface of the side parts morphology and shape, control method to obtain the parameters and the proper ranges. With good surface quality of forming parts and parts by plane block selection of parameters, verify the effectiveness of the process parameters, uniform metal droplet spray forming technology further in small complex It lays the foundation for the application of the forming field of the miscellaneous parts.

【学位授予单位】：西北工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TH16

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