环模成型机楔形区域物料运动速度与压力分析

环模成型机是生物质压缩成型主要设备,由于工况复杂性,不易测得其内部物料运动特性。对粉碎后的沙柳细枝颗粒在环模成型机内的运动速度与压力进行了研究。运用流变学理论建立物料在楔形区内的速度方程,并利用有限元软件Fluent对该区域内物料的塑性流动建立模拟仿真,应用动网格技术和UDF在仿真中实现环模和压辊旋转。通过Fluent仿真模拟得出物料在楔形区域内速度矢量图及速度和压力云图。前者用于分析物料在该区域内的运动方向。后者通过改变环模最小模辊间隙、模孔直径、模辊直径比,得出不同的物料速度和压力分布云图,用于分析物料在楔形区域内的运动速度和压力分布状况,及其对物料成型过程的影响。通过对比,环模成型机采用最小间隙为2.0 mm,模孔直径为10 mm,模辊直径比为2.25的参数时,对沙柳细枝颗粒致密成型效果和效率较好。上述结果可为研究其他生物质物料在环模成型机楔形区域内的运动提供理论支持和方法借鉴。

Velocity and Pressure Analysis of Particles in the Ring-die Extrusion Moulding Machine

Ring molding machine is the main equipment of biomass compression molding machine. Its internal material movement characteristics is not easy to be measured due to its complexity. This paper studied the movement velocity and pressure of crushed salix twig particles inside of ring moulding machine. Based on the theory of rheology, the paper established a velocity equation for the material in the wedge area of the machine, simulated its plastic flow with software Fluent, and used dynamic grid technique & UDF to move the ring die and press roll in the simulation. Then the velocity vector, velocity and pressure color nephogram of the particles in the wedge area were obtained. The former was used to analyze material movement direction in this area. By changing the minimum clearance, diameter ratio of the ring die & press roller and die orifice diameter, the latter obtained different color nephogram, which was used to analyze the movement velocity, pressure distribution and influence on material forming process. Through comparison, it was found when the ring moulding machine, minimum clearance was 2.0 mm, diameter of die orifice was 10 mm, and diameter ratio of the ring die & press roller was 2.25, the compact molding effect and efficiency of the salix twig particles were better. The above results provided theoretical support and method reference for studying movement characteristics of the other biomass material in the wedge area of ring moulding machine.