Optimization Of Screw For Special Extruder For LDPE Materials

Single screw extruder is a major equipment in the production of plastic products,and the screw as its core components,Its design quality will directly related to the performance of the whole machine.Right now,with the development of science and technology as well as people living standard rise,more and more high to the requirement of plastic products,led to the design of the screw with each passing day.Therefore,using parameterization design method for the extruder screw,can greatly improve the efficiency of the design of the screw,And take tructure optimizationto for parametric screw,can design more reasonable,more outstanding the screw in order to improve the energy saving efficiency.In view of the complex structure of the screw,using the traditional empirical method,time-consuming.Therefore,this article aimed at this phenomenon,According to the relationship between the structure parameters of screw and related theory,wth the help of 3D modeling software Pro/E,established the parameterized3 D model of the extruder screw for LDPE material.In order to operater convenient,taking secondary development for the design process of this screw parameterized model.Secondary development is mainly by using Pro/E’s own secondary development Toolkit Pro/Toolkit,then on VS2008 work platform,extracting key structure parameters from 3d parametric model of screw extraction using C language to write the user application.In this paper,established a user menu in the main menu of Pro/E directly,and according to the key structure parameters of the screw designed a friendly UI dialog box,The user can invoke parameter dialog through click menus directly,designer can change the parameters according to the need,then the model reconstruction,it can save time and improve the efficiency of the designer greatly.Using the front development application,this paper established a 3D model of the extruder screw for LDPE,for the defects of aircraft plasticizing degree is not highly and extrusion instability,taking a optimal design for the parameters of themetering section.First of all,building the numerical modeling of the flow in the metering section,analysis the state of the melt flow in the spiral groove,Including velocity、pressure、mass flow rate etc,and set up the constitutive equations of extrusion materials LDPE commonly used models.Then according to the processing conditions by experiments,for the simulation of melt flow in the segment by using Polyflow,and analysis of the model is verified conforms to the actual machining process.Then based on this model,according to theoretical analysis can get four structural parameters which has a great influence on quality of extrusion and extrusion production: groove depth、 measuring length、pitch、spiral rib width and according to the experience to determine three different levels of each parameter,.Using orthogonal table to arrange the experiment,simulating the process of melt flow in the metering section.And taking a range analysis for nine experiments according to the indicators of pressure gradient,shear rate,power consumption,the average temperature of extrusion,drawing the curve for the effect of individual parameters on the evaluation index according to the data from experiment,analyzed the influence of various parameters on these indexes,combined the table of range analysis,determine a set of optimal structural parameters of metering section.Finally improved the plasticizing efficiency and quality of extrusion of this model.And by using the experimental optimization of process parameters on the simulation for the optimized screw,contrast analysis of the two groups of extrusion effect under different process parameters,get a combination which more suitable for the structure parameters of the process parameters.