分段沉积/雕铣快速成形工艺中的材料选择与匹配问题及工艺实现

【作者】 赵宝民；

【导师】 江开勇；

【作者基本信息】 华侨大学 ， 机械制造及其自动化， 2005， 硕士

【摘要】 分段沉积/雕铣快速成形是一种基于堆积成型和传统成型相结合的复合成型方法,同时具有了堆积成型的柔性和传统成型的高精度。在该工艺中,按照工件可加工区域进行分段,对干涉区域和非干涉区域分别采用对工件材料直接加工和在支撑材料上复制型腔的方法进行加工,工件材料和支撑材料分别采用不同的材料。因此选择一对合适的零件材料和支撑材料是实现该工艺过程的基本前提。因此,本文主要致力于寻找一种合适的材料,来满足这种技术的加工需要。在此基础上,优化分段沉积/雕铣成型的工艺方法,进而实现一些特殊零件的制造。 首先,材料的选择应该满足严格的匹配关系,即工件材料固化的峰值温度不能超过支撑材料的熔点,两种材料应当互不相溶,加工完毕后,工件材料可以方便的从支撑材料中分离,而且支撑材料能够对工件材料起到很好的装夹作用。通过对多种材料匹配的分析,分别选择热固性的环氧树脂和热塑性可机加工蜡作为工件材料和支撑材料。根据单纯的环氧树脂在热匹配和切削性能上存在的不足,提出以铝粉作为填料的填充型环氧树脂替代纯环氧树脂作为零件材料,并通过正交实验的方法对填充型环氧树脂在不同组成成分材料的固化时间、峰值温度、收缩性、导电性、拉伸强度、应力—应变行为以及加工性能等分别进行了测试,通过合理化分析,选择最佳材料配比方案。 其次本文深入分析了分段沉积/雕铣成形工艺中材料变形问题,如塔形效应、整体变形、翘曲变形等,提出了一些具体的工艺改进措施,如采用封闭式堆积,应用隔热恒温型腔抑制工件翘曲等。对不同材料区域间隙的产生、内尖角/锐边的产生以及工件各层间工艺的调整做了深入的探讨,并通过一系列的工艺措施实现材料的高效粘接,同时对刀具的选择应用提出新的观点和看法。 最后论述了三维实体模型分段的基本策略和软件开发的思路。对实现分段沉积/雕铣快速成形工艺的一体化加工成型装备研制方案作了系统的分析,实现了各单元技术的集成,利用自主开发的一体化装置,开展了大量的验证性加工实验,提交了部分典型零件的加工实例。更多还原

【Abstract】 The Decomposed Deposition and Sculpture (DDS) is a type of compound forming method, which is based on the combination of material deposition process and traditional CNC machining. It has the characteristics both of the high accuracy of traditional machining and the high flexibility of Rapid Prototyping technology. This process is carried out by decomposing a CAD solid model into a sequent segments according to the part’s interfere and non-interfere area. The interfere area is processed directly, and the non-interfere area are processed by copying impression on the support material. The part material and the support material are different. Thus choosing a couple of appropriate materials of part and support is the premise for realizing the craft’s process. Therefore, this thesis concentrates on looking for a couple of appropriate materials to satisfy the process demand. On this foundation, the Decomposed Deposition and Sculpture’s technical method is optimized, and a lot of special parts’ manufacture is realized.Firstly, the choice of the materials should satisfy the strict match relation, namely the peak value of part material solidified temperature can’t exceed the melting point of the support material, and two kinds of materials should not dissolve mutually. After process completely, the part material can conveniently separate from the support material, and the support material can made the packing clips function to the part material. Through analysis of various of match materials, hot-solidified epoxy colophony and thermoplastic and machinable wax are chosen as part material and support material. According to the shortage of pure epoxy colophony in the hot-match and machinability, that the filled-material with aluminum power takes place the pure epoxy colophony as part material is advanced, and by the way of orthogonal experiments the performance of the different component filled-material, including time of solidify, peak value temperature, contractibility, electrical conductivity ability, stretch-strength, stress-deformation, machinability etc. are tested. Through rationalization analysis, the best project of material matching is selected.Secondly, the material shrinkage and distortion are deeply studied in the thesis, somemeasures of technology are put forward to. The thorough study on the generation of clearance in different material zones, inside sharp-angle and craft adjustment of each layer of the part has been done. Through a series of technological measures, the efficient material cementation is realized. In addition, the new viewpoints and opinions of cutter’s choice and application are advanced.Finally, the regulations of decomposition of three dimensional solid and the software exploitation strategies are discussed. The incorporate equipment design project for the SSD is systematicly analyzed, and all the unites integration is realized. By making use of the self-determination exploitation incorporate equipment, some verification experiments were developed, and a part of typical parts’ process examples were handed over.更多还原