Hydraulic Simulation Of Outflow From Tundish-cover Method And Optimization Of Cover Design Parameters

Due to its good comprehensive performance,simple production process and relatively low cost,ductile cast iron is widely used in production and life,such as vehicle and ship parts,mechanical parts,etc.The output of ductile iron in my country is increasing year by year,and the essential link that determines the quality of ductile iron is the spheroidizing process.In recent years,as my country's requirements for casting quality and energy conservation and environmental protection have continued to increase,many companies have begun to use tundish process instead of pour-over process.But so far,companies are different in terms of cover structure and process parameter design,and there is no unified design standard;The cover method has strict requirements on the height of the vicotic diameter and the pouring liquid tank and the effective highness of the water,and the selection of each process parameters directly affect the spherination effect and metallurgical quality of the iron solution;The temperature drop of molten iron is obviously greater than that of ordinary flushing.Therefore,the related theoretical model is established by in-depth study of iron fluids in the process of covering the glomerization process,further optimizing the cover spheroidization process and design parameters,and improving the iron solution.The quality of spherulation,accelerated cover spherulation process promotion process and the batch stability production of ball iron parts have certain practical significance.This paper establishes the cup-hole two-unit hydraulic simulation experimental model to explore the correlation law between the actual pressure head of the orifice,the orifice flow rate,the flow coefficient and the liquid level of the cup,the section ratio,the shape of the cup bottom,the structure and the size of the leak established the theoretical calculation model of the outlet flow coefficient of the orifice,introduced the design procedure of the cover and explored the influence law of the design parameters of the cover on the quality index of spheroidization metallurgy.The main conclusions are as follows:(1)Through hydraulic simulation experiments,the basic characteristics of the outflow from the orifice and the pressure head distribution around the orifice are observed and analyzed.With the increase of the hole diameter,the degree of turbulence in the pouring cup increases,and the spraying state of the outflow stream from the orifice becomes more and more.Intense,the outflow stream tends to shift to the outside;the farther away from the hole center,the greater the actual pressure head In addition,the pressure head in the center of the orifice under positive pressure is much larger than that under normal pressure;the outflow velocity of the orifice has obvious asymmetry,and as the aperture of the leak hole increases,the asymmetry of the flow velocity increases significantly.(2)The effects of different pressure states,cross-sectional ratio,liquid level height,fillet coefficient R/?₀ and cup bottom structure on the actual pressure head,orifice flow velocity and discharge coefficient are comparatively studied.With the increase of the cross-sectional ratio,the actual pressure head,orifice flow rate and flow coefficient firstly increase sharply,and then tend to flatten;and the actual pressure head under normal pressure is smaller than that under positive pressure,while the orifice flow velocity and flow rate The coefficient is always larger than under positive pressure;When the cross-sectional ratio K>42.25,with the increase of the cross-sectional ratio,the discharge coefficient increases with the increase of the height of the liquid pool;As the fillet coefficient R/?₀ increases,the flow coefficient increases first,and then tends to level off;under the conditions of a certain leak hole diameter and liquid level,the flow coefficient of the curved bottom pouring cup is greater than that of the flat bottom pouring cup.(3)Through the multiple regression analysis method,the flat bottom pouring cup,the curved bottom pouring cup,and the theoretical prediction model of the outflow coefficient ? of the lid-pack method under positive pressure and normal pressure are obtained,and the optimal design of the outflow process parameters of the lid-pack method can be realized.(4)Based on the hydraulic simulation experiment,a calculation method for the outflow engineering of the cover-pack is established,The theory predicts the critical liquid level to avoid the funnel-shaped suction vortex at the water inlet.According to the actual production of a company,the cladding structure and process parameters are optimized according to the iron output of 1.15t.The recommended parameters of the curved bottom pouring cup are the leak hole diameter ?₀=6.3cm,the orifice fillet radius R=9mm,and the pouring cup diameter D=46cm.The corresponding temperature drop of molten iron is 80?100?,which is 30?40?lower than before,The injection time is about 60s,and the absorption rate of magnesium is much higher than that of the flushing method and the wire feeding method,reaching 70%.