Research On The Characteristics Of Solid Conveying With Helical Grooves Feed Zone In Extruder

Extrusion molding is one of the important methods of polymer molding processing. At present, a barrel with axial grooved feed zone is widespread applied to the polymer extrusion processing. However, there are some common disadvantages of this system, such as overtaxed pressure build up of the feed zone,throughput variations, wear serious between the screw and barrel. In this paper, we developed a helically grooved feed single-screw extruder, adopting helically grooved bushing of forced feeding structure. This system can improve solid transportation characteristics, increase the extrusion throughput, and reduce extrusion energy consumption.In this paper, it is studied on the solid transportation characteristic of the helically grooved feed single-screw extruder. Based on the double flight driving theory and arc model brought forward by XUE Ping et al of Beijing University of Chemical Technology, we take the conveying mechanism of solid conveying section in helically grooved feed single-screw extruder as research object; the energy consumption equation of helically grooved feed single-screw extruder was deduced. The boundary condition equation that the transformation from the friction drag conveying to the positive conveying was validated. According to the positive conveying condition equation, extrusion production and energy consumption equation, helically grooved bushing of forced feeding structure has been designed, and implied in the practical production.Theoretical analysis and discuss the influence of the helical grooves feeding bushing geometric structural parameters: length, numbers, width, depth and helical angle, screw structural parameters, operation parameters and physical parameters on the pressure, extrusion production and energy consumption of the material in the extruder solid conveying section.During this project, with the new designed helically grooved feed single-screw extruder, several experiments are designed to study the affect of the helically grooved bushing on solid convey by changing materials, speed and so on. Extrusion throughput and energy consumption comparison experiments, using HDPE and PPR separately in the helically grooved feed single-screw extruder and traditional extruder, have been conducted. The research results indicate that the helically grooved feed single-screw extruder has ideal characteristic of positive displacement conveying, which has good conveying ability, high production capacity. Experimental results confirm the theoretical predictions, the theoretical research and experimental results have good uniformity. The actual extrusion production is consistent with the theoretical analysis. Extrusion throughput increased by 20% ~ 30% compared to the original.In this paper, we deduced the energy consumption equation of helically grooved feed single-screw extruder, which enrich the double flight driving theory. The design thought way adopted to design the main structural parameters of the helically grooved feed bushing, contribute to form the design standard of the helically grooved feed bushing. This study will serve as the theory basis for the optimum condition of helically grooved feed extruder design and processing polymer for lowering energy consumption and increase production.