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对反应注射充模过程中的铺展流、射流、绕流和气泡等特性进行了分析研究,并讨论了模具浇口结构及位置对充模的影响,给出了影响了设计方法。 相似文献
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注射成型中充模阶段熔体喷泉流动的研究 总被引:1,自引:0,他引:1
建立了聚合物熔体充模流动的数学模型,并结合实验结果对充模流动中喷泉效应进行了分析,得到了一些结论。为整个充模过程的控制机理提供了理论依据,对控制注射工艺、模具设计有指导意义。 相似文献
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本文对反应注射充模过程中的铺展流、射流、绕流和气泡的特性进行了分析研究,并讨论了模具浇口结构及位置对充模的影响,给出了制品的设计方法。 相似文献
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反应注射成型充模参数的选择 总被引:3,自引:1,他引:2
本文在分析聚氨酯反应注射成型反应动力学基本方程的基础上,对影响选择充模过程的主要因素进行了分析,并得出聚氨酯反应注射成型流动阶段充模区域图。 相似文献
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采用Level Set两相流方法模拟了熔体充模过程,避免了处理复杂的边界以及用Ghost方法将熔体内的速度值外推到熔体外的情况。分别对型腔水平中面与垂直中面的充模过程进行了模拟。讨论了不同注射速度、不同注射口数量以及不同Reynolds数对充模过程的影响,得出了不同时刻各种情况下熔体界面的位置与充模过程刚结束时型腔内的压力分布,分析了熔体在型腔内运动的不同阶段的特点及形成不同阶段的原因。结果表明,在注射口宽度与型腔宽度相差不大的情况下,如果采用中低速充模,则整个充模运动过程以比较平稳的扩展性运动为主,充模较完全,熔体不发生破裂,制件效果较好。充模速度越大,熔体达到平稳流动的时间越短,充模过程越短。数值模拟结果与实验结果一致,同时表明Level Set两相流方法在求解拓扑性质发生较大变化问题时具有很大的优势。 相似文献
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本文建立了描述气体辅助注射成型充模流动过程的数学模型,并采用有限元/有限差分混合算法进行数值求解,在对移动边界的处理上采用控制体积法对充模过程中的两类移动边界:熔体前沿、熔体-气体边界进行跟踪,从而实现气体辅助注射成型充模过程的数值模拟。通过对一平板带厚筋结构进行数值分析验证了本文给出的理论算法及软件的可靠性。 相似文献
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聚氨酯反应注射成型充模流动研究 总被引:1,自引:0,他引:1
聚氨酯原料体系反应注射成型(RIM)制品在汽车构件、商用机器外壳等制造方面得到越业越广泛的应用,同时RIM制品也朝着体积大、注射速度快的方向发展。但目前在模具设计及工艺参数选择中仍采用经验或尝试的方法,耗费大量人力物力。为此,本文对长扁平板模聚氨酯反应注射成型(RIM)充模流动过程进行了实验研究并建立了计算模型。得出的压力计算公式与实验结果进行了对比。结果表明在弃模时间tf远小于凝胶时间tqm时充 相似文献
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RTM一维单向流动模型的理论概况及研究 总被引:1,自引:0,他引:1
本文研究了牛顿流体在铺置纤维预制件的RTM平板模具中,一维单向恒流和恒压流动的渗流模型.通过求解析解,求出模型的各个可测量物理量之间的关系,对传统的解析方程进行了拓展和改进,提供了在不透明模具中测定渗透率的方法.即在恒流条件下,只需利用压力传感器和恒流泵的读数即可测定预制件的一维渗透率;或者在恒压条件下,利用数字流量计和压力表的读数测得一维渗透率.而这些解析解的关系式也可用于实验预估模具中的压力分布、充模时间等. 相似文献
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RTM二维径向流动模型的理论概况及研究 总被引:1,自引:0,他引:1
综述了牛顿流体在放置了各向同性和各向异性预制件的RTM平板模具中二维径向恒流和恒压渗流的流动模型.对各个模型的可测量物理量之间的关系通过求解其解析解进行了必要的拓展补充推导和研究分析,对传统的二维解析方程进行了拓展和改进,提供了在不透明模具中测定渗透率的方法.即在恒流条件下利用压力传感器和恒流泵测定预制件的二维渗透率;或者在恒压条件下利用数字流量计和压力表测得二维渗透率.这些解析解的关系式也可用于实验预估模具中的压力分布及充模时间等. 相似文献
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根据微阵列结构制品熔体的充填特性,设计直径为500 μm的微圆柱阵列结构制品模型,并加工注射成型模具,对微圆柱结构制品熔体的充填规律进行实验和模拟研究。结果表明:微结构制品熔体的充填过程和流动前沿形态的实验结果与模拟分析虽然在趋势上比较一致,但在微圆柱成型过程中,流动前沿的形成过程和充填高度的模拟变化规律与实验结果有一定偏差;实验还发现,前期充填阶段对微圆柱成型的贡献较小,微圆柱内流动前沿的形成受到熔体流动速度、微圆柱模壁、熔体流动惯性影响较大,熔体流经微圆柱结构时产生向上的流动涡流,流动前沿形状呈偏心椭球冠状并逐渐发展成球冠状。 相似文献
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为了研究塑料熔体在模腔内的流动行为,设计制造了浇口动态磁化装置,通过磁化试验,测量中心浇口圆盘模腔内的熔体在各个时刻的流动位置和充模时间,可以直观地分析塑料熔体在模腔中的流动状态。 相似文献
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高精度雷达罩RTM工艺与模具设计 总被引:1,自引:0,他引:1
介绍了RTM(树脂传递模塑)工艺的特点,并对RTM法制造高精度飞机雷达罩的充模流动、工艺控制要点和模具设计方法等作了简要的论述。 相似文献
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L. T. Manzione J. S. Osinski G. W. Poelzing D. L. Crouthamel W. G. Thierfelder 《Polymer Engineering and Science》1989,29(11):749-761
Multi-cavity transfer molding is an important process step in several electronic and photonic technologies. In some applications, uniform filling of the cavities of the mold, or mold balancing, is required. A semi-empirical flow model to predict mold filling patterns was developed. The algorithm is a one-dimensional network flow simulation that uses experimental pressure drop data to determine the volumetric flow rate through the gates and runners. A comprehensive experimental program was undertaken to determine these hydraulic resistances for different flow rates and mold geometries. A theoretical treatment is also described to compute hydraulic resistance from gate geometry. Uniform gate resistances provide unbalanced filling and higher velocities in the cavities. Balanced filling can significantly reduce the molding compound velocity and the flow induced stresses, but imperfect balancing compromises the benefits. Experimental filling patterns were obtained for two sets of gates. The agreement between the model and the experiments was satisfactory, and the discrepancies were attributed to correctable phenomena. 相似文献
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Compared with SCRIMP based on the high-permeable medium, SCRIMP based on grooves has the advantage of a much higher mold filling rate. This paper analyzes the influences of various molding conditions on mold filling and presents models that can be used to predict the filling time and flow pattern in SCRIMP based on grooves. Mold filling experiments were carried out to investigate the effect of various factors such as the size of the groove, groove spacing, number of fiber layers and resin viscosity on mold filling. A leakage flow model was developed to simplify the simulation of the mold filling process in SCRIMP based on grooves. An “equivalent permeability” was introduced to represent the average flow capacity in the grooves. Compared with the Control Volume/Finite Element Method (CV/FEM) model, the leakage flow model greatly reduced computation time and yet provided simulation results that were in good agreement with experimental observations. 相似文献
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基于流体运动的基本理论,建立了塑料熔体填充流动的数学模型,利用Moldflow软件对轿车后视镜外罩进行了模拟仿真,分析了壁厚、浇口位置、流动平衡、流动前沿温度、熔接痕以及气穴位置等对成型结果的影响,为模具设计、注射工艺的确定提供了量化指导。 相似文献
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Finite element modeling and experimental investigation of mold filling in resin transfer molding (RTM) have been performed. Flow experiments in the molds were performed to investigate resin flow behavior into molds of rectangular and irregular shapes. Silicone fluids with viscosity of 50 and 100 centistoke as well as EPON 826 epoxy resin were used in the mold filling experiments. The reinforcements consisted of several layers of woven fiberglass and carbon fiber mats. The effects of injection pressure, fluid viscosity, type of reinforcement, and mold geometry on mold filling times were investigated. Fiber mat permeability was determined experimentally for the five-harness and eight-harness woven mats. Resin flow through fiber mats was modeled as flow through porous media. Pressure distributions inside both types of molds were also determined numerically. In the case of resin flow into rectangular molds, numerical results agreed well with experimental measurements. Comparison between the experimental and numerical results of the resin front position indicated the importance of edge effects in resin flow behavior in small cavities with larger boundary areas. Reducing the resistance to resin flow at the edge region in the numerical model allowed for good agreement between the numerical simulation and the physical observations of the resin front position and mold filling time. 相似文献