Rubber Flow Analysis And Extruder Head Runner Design Based On Fluent

The development of the auto industry has a huge demand on tire, tread and sidewall are important part of the tire, so it is very important to ensure their quality in the extrusion process. Rubber need pass a flow runner which has a circular entrance and a rectangular exit when rubber is extruding, guarantee the uniformity of exit is one of the critical key factors in flow runner design. The traditional manufacture method of flow runner is “try and error”, which has long production cycle, low yield and high cost. With the development of the computer technology, the application of using numerical simulation method to analyze polymer melt and design flow optimization is more and more widely. In this paper, the research is carry out combined with the enterprise needs; the research method is combined experience design with numerical simulation; the design principle is that the lateral velocity of flow exit is uniform; the mathematical model is established, the rubber flow behavior in flow runner is analyzed by Fluent, and the runner structure is optimized.The runner structure is designed combined flow shape with damping analysis, and the numerical simulation is made by Fluent, the result shows that it cannot meet the design requirement when the shunt is only designed in the upper part of damping. Then the flow runner structure is improved, and the numerical simulation of two kinds of structures are made, the comparison of the two kinds of schemes indicates that it can have a good shunt effect when both of the upper and bottom of damping have good choke flow effect. So both of the upper and bottom of damping should be considered when flow runner is designed.Numerical simulation of rubber flow in different damping parameters for improved flow runner structure are made, the velocity field, pressure field, shear stress field are got, the influence of different flow runner structure on flow are: the change of damping upper Angle affect the velocity magnitude of exit middle, and with the increase of the angle, the velocity of exit middle decreases; the change of damping middle thickness affect the velocity magnitude both of exit both ends and middle, and with the increase of the damping thickness, the velocity of the exit middle decreases, the velocity of exit both ends increase; the change of damping lower angle affect the velocity magnitude of exit, the velocity distribution width of exit, and the uniformity at the junction of exit middle section and both ends, and with the increase of the angle, the velocity of exit middle decreases, exit both ends increases, velocity distribution widened, but the junction of middle both ends appear trough, the velocity uniformity become bad. Flow structure was optimized according to the above principles. Damping parameters are: A=12°, B=0.025 m, C=35°, the average speed deviation of simulation is 1.28%.Numerical simulation of rubber flow are made for different production conditions, The influence of different production conditions on the flow are: temperature change has no influence on exit velocity, the increase of inlet pressure cause the velocity of exit middle faster than both ends, rubber viscosity reduction cause the velocity of exit middle faster than both ends.Flow runner is produced according to the selected optimal structure, experiment is made, the uniformity of the product thickness is measured, The result(error is 1.31%) shows that the flow runner design can meet the design requirement(error is 5%). The causes of error are analyzed combined with the influence of the structure and process parameters change on rubber flow, get the cause of error may be the model simplification in numerical analysis, the flow runner production error as well as the inlet pressure and viscosity reducing caused by repeated use of rubber.