Numerical Analysis And Optimization Of The Extrusion Flow Field Of Double-layer Wire Coating

Composite extrusion technology has been widely used in modern extrusion processing,mainly involving the extrusion process of treads,pipes,profiles and other products.However,it still faces the problems of irregular composite lines of various layers,offset of composite interface and extrusion swelling.In the process of coating and extrusion of double-layer composite wire,there are quality problems such as large deviation of cross-section composite wire roundness and uneven thickness of inner and outer layers,which will lead to the reduction of cable service life and even the exposed core wire.In this paper,the 2.5mm~2 double-layer composite wire is taken as the research object to analyze the influence law of the head structure parameters,material physical parameters and process parameters on the flow field in the head,and to determine the relationship between the flow field uniformity index and the extrusion quality.In order to optimize the cable extrusion process.The research process of the full text is based on the finite element numerical simulation technology and the method of response surface optimization.For the extrusion process of the extruding double-layer composite die,the influence law of each factor on the flow field is explored.Analyze the sensitivity of each factor’s value interval.Sensitivity,clarify the relationship between flow field distribution and extrusion quality,establish an objective function that reflects extrusion quality and efficiency,and describe the relationship between the objective function and various factors quantitatively.In order to guide production.However,in the optimization of the process,there is a mutually restrictive relationship between various factors,which makes the optimization design of the entire production process quite complicated.Therefore,the response surface method is used to analyze the interaction of factors and multi-objective optimization,and finally obtain the optimal combination of factors.The specific numerical simulation methods and cable extrusion quality optimization contents include the following:（1）The Bird-Carreau constitutive equation is used to establish the finite element analysis model of the double-layer composite die covering extrusion,and use the POLYFLOW software to analyze the pressure field and velocity field of the extrusion process.The results show that the distribution of the flow field in the co-extrusion setting section is an important indicator to determine the uniformity of the flow field at the outlet section,and the flow field in the co-extrusion setting section is determined by the head structure parameters,material physical parameters and processing technology parameters.At the same time,the law of the influence of each parameter on the flow field distribution of the outlet cross-section and the sensitivity of each value interval are determined,which provides data support for the subsequent optimal design of the roundness of the composite wire of the cable cross-section.（2）The changes of two key quality indicators（the position of the composite interface and the extrusion expansion of the outer surface）during the composite extrusion process were studied,and the influence rules of the main factors on the offset of the composite interface and the change of the outer diameter were analyzed.The sensitivity of each value interval provides data support for the optimization of the extrusion thickness of the subsequent two-layer rubber compound for the wire.（3）The Plackett-Burman method has been used to design experiments and screen important influencing factors.Then conduct response surface analysis on the important influencing factors to establish the response surface model of the objective function and each factor.The coefficient of variation,complex correlation coefficient,repair positive correlation coefficient,distribution of predicted and simulated values and analysis of variance were used to evaluate the response surface model.Finally,experiments were designed to verify the validity of the equation.（4）Aiming at the production of wire products with different performances using the same composite head,the optimal design points for each factor meeting multiple extrusion quality objectives were obtained,and the POLYFLOW simulation test was carried out to verify the optimal design points.The results show that the cross section can be guaranteed High-efficiency production under the premise of the roundness of the composite wire and the thickness of the inner and outer cladding,providing guidance and suggestions for industrial production.