振动场下FFF热熔喷头内熔体表观黏度的理论研究

Theoretical Study on the Apparent Viscosity of Melt Inside the Fused Filament Fabrication Extrusion Liquefier Under Vibration Field

热熔喷头内部熔体的表观黏度是影响熔丝制造成型(FFF)产品机械性能的关键因素之一.本文首先提出利用振动改善FFF热熔喷头内部熔体表观黏度的方法,即对喷头施加纵向的正弦振动力场;然后针对施加振动后热熔喷头内部熔体的表观黏度进行了理论建模,并利用已有文献中的实验结果验证了理论模型的正确性;最后,利用所建模型探讨了施加不同频率振动后熔体表观黏度的变化规律,阐明了相应机理.研究表明:熔体表观黏度的理论与实验结果吻合度较好,理论模型正确;对热熔喷头施加振动场后,熔体表观黏度有效值随着振动频率的增大而逐渐降低.

The apparent viscosity of the melt inside the extrusion liquefier is one of the key factors affecting the mechanical properties of fused filament fabrication(FFF)products.A method applying a longitudinal sinusoidal vibration to the FFF extrusion liquefier is proposed to improve the apparent viscosity of the internal melt.Then the theoretical model of the apparent viscosity of the melt inside the extrusion liquefier with vibration applied is carried out,and the experimental results from the existing literature are used to verify the correctness of the theoretical model.Finally,the variation of apparent viscosity with different-frequency vibrations applied is discussed through the model,and the corresponding mechanism is clarified.It is shown that the theoretical results agree well with the experimental ones,validating the model’s feasibility.When the vibration field is applied to the extrusion liquefier,the effective value of apparent viscosity will decrease with the increase of vibration frequency.