Development Of Forming Die Of Submerged Entry Nozzle In FTSC Thin Slab Continuous Casting

As a short process near net shaping continuous casting and rolling technology,thin slab continuous casting and rolling process is one of the vital revolutionary technologies in the steelmaking industry after oxygen converter steelmaking and continuous casting technology.While submerged entry nozzle(SEN)is the core functional element in thin slab continuous casting which works in severe conditions should have special structure.SEN together with mold flux and crystallizer are considered as the three critical technologies in thin slab continuous casting.Limited by the opening of the crystallizer,the general outline of SEN for FTSC thin slab continuous casting is thin-walled flat shape,while its upper part is cylindrical,and then gradually transits downward to flat shape,which brings great difficulties to the forming and processing.SEN is composed of functional gradient materials and is produced by cold isostatic pressing process.If "near net shaping" forming of SEN is realized,the raw materials could be saved,the production process could be simplified,and in addition the stability and the reliability could be improved,so it has been a persistent goal that relevant industry pursued.Ariz algorithm of TRIZ is adopted in our investigations to develop the die for“near net shaping” forming of SEN for FTSC.By means of which,the problem of cold isostatic forming system is converted into a simple problem model and through the following steps as problem analysis,contradiction determination,project solution evaluation and solution improvement etc.,the final technical solutions are obtained,which is a kind of urethanes sheath with gradient hardness structure.Furthermore,the finite element numerical analysis method is applied to construct both the constitutive model of carbon containing powder material and the super elasticity constitutive model of the super elastic sheath.MSC.Marc is adopted to analyze the forming process of SEN with the above mentioned urethanes sheath.Variations of the stress and density distributions and the outline dimensions during the cold isostatic pressing forming process at the reducing area,slag line and taphole are investigated respectively.Also,the effect of the shape,hardness and friction coefficient of the die on the pressed nozzle is analyzed.At last,the mold design has optimized and verified.The technical solutions obtained have successfully been authorized national invention patents and are expected to be applied to the whole industry,which may facilitate the technological innovations in the forming process of SEN for FTSC.At the same time,the significance of TRIZ and the finite element numerical analysis applied to the development and improvement of the production process of functional refractories has been verified.