热、力及其复合外场原位辅助熔融沉积成型技术研究进展

In Situ Thermal/Force Field-assisted Fused Filament Fabrication:Current Status and Prospects

熔融沉积成型(fused filament fabrication,FFF)是典型的聚合物增材制造技术之一,因其原料利用率高,成型原理简单且成本低而受到广泛关注。然而,FFF技术采用逐层堆积的加工方式,导致其成型件的层间界面结合强度较弱、宏观力学性能呈各向异性,因此较少用于工业领域关键零部件的制造。为此,发展了外场原位辅助的FFF技术,借助热场、力场及其复合外场,原位促进FFF成型过程中的层间结合行为,进而提高FFF成型件的宏观力学性能。本文从FFF成型的层间结合现象出发,归纳无定形聚合物和结晶性聚合物的层间结合机理,概述热场和力场对层间结合的影响机制,综述各类热、力及其复合外场辅助FFF技术的研究进展,并讨论各类原位辅助技术对FFF成型件力学性能的改善与不足,最后展望该技术在材料、工艺与装置等方面的发展前景和趋势,为促进FFF技术的工程应用提供理论支撑和技术参考。

Fused filament fabrication(FFF)is one of the most widely-used polymer-based additive manufacturing technologies,with advantages of high raw material utilization,simple working principle,and low cost.However,nowadays FFF technique tends to be used to fabricate prototypes rather than final products,especially in industrial area,since it produces polymer parts with weak interlayer interfaces and therefore anisotropic mechanical properties due to its later-by-layer manufacturing principle.During FFF process,neighbour layers weld at the interface through surface wetting,molecular diffusion and entanglement,highly depending on the thermal profiles experienced by the deposited polymer strands.To this end,the in situ external field-assisted FFF techniques have been developed,aiming at promoting the welding behaviours between adjacent layers during the FFF process,with the help of thermal and force fields and their combination external fields,which in turn improve the mechanical properties of the FFF parts.This paper firstly summarizes the state-of-art of the modeling and experiments devoted to exploring the interlayer welding behaviours of amorphous and semicrystalline polymers during FFF process.Then,various thermal,force and their combination external field-assisted FFF techniques are presented,from aspects of the principles and their effects on the mechanical properties of the FFF parts.Finally,the challenges and prospects of the thermal/force-assisted FFF technology are discussed from the perspec tives of materials,processes,and devices,and the development and application of FFF technique are emphatically analyzed.