新型螺杆挤出机固体输送理论的研究

Study on the Theory of Solid Conveying of the Novel Screw Extruder

介绍了一种嵌套式新型螺杆挤出机。在固体输送段对内螺杆的两种等效情况下固体塞的运动和受力作了深入分析。理论上证明了这两种情况下的固体输送机理与外螺杆的情况相同,均建立在固体摩擦输送机理基础之上;讨论了牵引角、摩擦因数和螺纹升角对上述三种情况固体输送流率的影响。结果表明,螺杆旋转机筒静止和螺杆静止机筒旋转两种情况下固体输送流率相差不大,而螺杆机筒同时旋转情况下的固体输送流率远大于其他两种情况。增大牵引角、降低螺杆表面粗糙度和提高机筒内表面的摩擦因数均有助于提高固体输送流率。螺杆旋转机筒静止和螺杆静止机筒旋转这两种情况下最佳螺旋角均为17°左右,而螺杆机筒同时旋转情况下最佳螺旋角为15°左右。

A novel nested screw extruder was introduced. Motion and force of the solid plug in the solid conveying zone were analyzed deeply in the two equivalent cases of the inner screw. It was proved theoretically that the solid conveying theories of the above two cases are both on the basis of solid fraction conveying mechanism just as the outer screw. The influences of traction angle, coefficients of friction and helix angle on the flow rate of solids were discussed. With the same geometrical variables and process conditions, the solid conveying volumetric flow rate in the case of rotating screw and opposite rotating barrel is much higher than those in the other two cases, and the volumetric flow rate in the case of stationary screw and opposite rotating barrel is a little higher than that in the case of rotating screw and stationary barrel. The solid flow rate of the above three cases all can be improved with the increasing of traction angle. Both lowering the coefficient of friction between solid plug and screw and increasing the coefficient of friction between solid plug and barrel can improve the solid conveying flow rate. The best helix angle is about 17 degrees both in the case of rotating screw and stationary barrel and in the case of stationary screw and opposite rotating barrel, while the best helix angle is about 15 degrees for rotating screw and opposite rotating barrel.