| The submerged nozzle structure of slab continuous casting determines the flow state of molten steel in the mould,thus affecting the quality of the slab.Unreasonable submerged nozzle structure and continuous casting process parameters will aggravate the liquid level disturbance in the mould and reduce the quality of the slab.This paper takes the submerged nozzle of a medium and thick slab continuous casting mould in a factory as the research object,analyzes the relationship between the parameters of each nozzle and F value,and proposes the method of optimizing the structure and process parameters of the submerged nozzle by using F value,which is of great significance for improving the quality of the slab.Based on the theory of submerged efflux,the analytical solution process of F value,which represents the fluctuation of liquid level,is presented,and the change rules of F value and nozzle structure parameters and nozzle process parameters are analyzed,and the relationship between the conventional slab F value and nozzle inclination is obtained.Based on the relationship between the conventional slab F value and the dip Angle of the nozzle,a calculation model was established to solve the structural parameters and process parameters of the nozzle,and the relationship surface of the nozzle immersion depth,the nozzle diameter,the nozzle edge length and the casting speed when the F value was 4 in the slab mold of 1000×200mm in a certain factory was obtained,and the influence of the nozzle parameters on the liquid level in the mold was analyzed.Select throwing speed 1.4 m/min when the optimum parameters of the nozzle combination multiple sets of point on the surface,to establish the numerical simulation of flow field of molten steel in mould model,the mold for the computation of the flow of the molten steel in the groups of shuikou parameter corresponding to the liquid surface wave is high,the liquid surface in the mold flow velocity and flow field in the crystallizer and the comparison between groups of numerical simulation of liquid surface wave height and the liquid surface velocity,a group of nozzle parameters to get the most reasonable combination.Using the obtained optimal nozzle parameters,MATLAB software was used to solve the range of the billet speed when F value was between 3 and 5,and the reasonable range of the billet speed was between 1.21m/min and 1.57m/min.Establish the F value is 3,throwing speed 1.21 m/min and F value is 5,and casting speed of 1.57 m/min when the numerical simulation of flow field of molten steel in mould model,the mold for the computation of the flow of the molten steel in the analysis of the results of numerical simulation of liquid surface velocity and liquid surface wave height,the results show that the drawing speed range to meet is not easy to happen the conditions of the slag,verified the throwing speed range for optimal nozzle parameters under reasonable range. |
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