【作者】 王振华；

【导师】 刘会英；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2014， 硕士

【摘要】 骨组织工程是未来骨修复的发展方向。它用可生物降解的材料制造与骨骼形状和物理性能相似的、疏松多孔的人工骨支架作为新骨生长成型的载体。其中人工骨支架的制造尤为重要，采用熔丝沉积快速成型制造骨支架有很多优势，论文以此方法为研究对象，研究了与喷丝技术相关的几个问题。首先，分析了螺杆挤出理论，运用该理论和聚合物流变学理论，推导了非牛顿流体流经流道时螺杆转速与喷丝速度的关系。建立了细丝截面的数学模型，并推导了丝宽的计算公式。建立了细丝喷出后冷却的数学模型，同时求出了解。其次，对微型螺杆挤出系统进行了设计。建立了喷丝过程的仿真模型，用POLYFLOW软件仿真了几个主要螺杆参数对流率、停留时间、混合性的影响，根据结果优化了螺杆的设计。对细丝冷却过程温度变化及相关影响因素进行了仿真，包括流率、环境温度、流体流入喷嘴的温度对喷丝温度的影响；出丝横截面积、对流换热系数、喷丝温度、风扇转速等对冷却时间的影响。为确定合适的成型速度和提高成型速度提供了指导。最后，用实验的方式测定了送丝机构能提供的最大送丝力、丝宽、挤出胀大比和细丝的塌陷变形程度。更多还原

【Abstract】 Bone tissue engineering is the future development direction of bone repair. Ituses degradable biomaterial to manufacturing the porous scaffold which has asimilar properties with bones both in shape and physical. The scaffold is a carrier forgrowing and reshaping of the new bone. The manufacturing of the bone scaffold isobviously important. There are many advantages to make bone scaffold using fuseddeposition modeling. This paper studied several of the problems relevant.Firstly, screw extruding theory was analyzed. The relationship between thescrew rotational speed and the filament extruding speed was deduced using theabove theory and polymer rheology. The formula to calculate the filament width wasdeduced based on the model of the cross section which was established. Themathematic model of the filament cooling process was established and solved.Secondly, a mini-screw extruder system was designed. The Simulink modelsrelevant to the filament extruding process were built, and POLYFLOW was used tosimulate the influence of the main screw parameters on the flow rate, stay time andmixing property. The design of the screw was optimized based on the result. Thetemperature changing during cooling process and its factors were simulated,including the influence of the flow rate, environment temperature on the filamentextruding temperature; and the influence of the fluid temperature flowed into thenozzle; cross section area, heat exchange coefficient, filament extruding temperature,fun speed etc. on the cooling time. Thus provide a guideline to decide and improvethe scanning speed.Finally, experiments were taken to measure the maximum force which thefilament feeder can provide, the filament width, die swell ratio and filamentdistortion during cooling process.更多还原