Three-dimensional Numerical Simulation Of A New Cooling System For Casting Rolls In AZ31B Magnesium Alloy Twin-roll Casting

The twin-roll strip continuous casting and rolling technology is a new processing technology in the metallurgical field.The process feature is that the molten metal liquid is poured between two counter-rotating roll gaps,and the rapid solidification and rolling deformation are combined to complete the nearfinal forming of the liquid metal to the metal strip process.In the twin-roll continuous casting and rolling process of magnesium alloy strip,the design of the casting roll plays a very important role in the production quality of the strip.The form of the inner flow path in the roll core of the casting roll is constantly evolving,and the structure that appears is also diverse.But the form of the flow channel is all about how to dissipate heat faster and better,there is no good solution to the control of the edge temperature.According to the comparison of different metal production methods,casting and rolling is the fastest and simpler method for producing short-flow alloy strips.However,for different alloy strips,in order to cast a higher quality,it is necessary to ensure that the edge of the alloy strip is less cracked.Therefore,higher requirements are placed on the edge temperature adjustment of the casting rolls.Until now,all the casting rolls have not been able to artificially control the temperature of the side portions,which is also difficult to meet the requirements for reducing the degree of edge cracking during the casting and rolling process.This is also an unsolved problem in the field.The technical solution adopted in this project is to develop a new type of casting roll used in pairs.By adjusting the water flow distribution along the length of the roll body,the cooling intensity distribution of the axial direction of the casting roll is adjusted to realize the magnesium alloy casting strip.The quality of the edge of the material is improved.Firstly,it is planned to mathematically analyze the cooling water model inside the casting rolls,and determine the heat transfer equations and boundary conditions required for the simulation of the temperature field of the magnesium alloy melt in the casting rolls and casting areas.Secondly,it is planned to design a cooling water quantity adjustment sleeve,which is assembled into the cooling water inlet pipe of the casting roll core through a specific structure(which can be finely adjusted by rotation),thereby adjusting the cooling water in the groove on the roll core.The flow distribution is used to adjust the axial cooling intensity distribution of the sleeve.Finally,it is planned to use 3D modeling software Solid Works to model cooling water,roll cores,roll sleeves and magnesium alloys.First,the cooling water flow field,temperature field and magnesium alloy melt temperature field were simulated and analyzed before and after loading the water volume adjustment sleeve.Then,three kinds of assumptions were made on the distribution of the convective heat transfer coefficient of the cooling water in the sleeve.It is planned to combine the energy control equation of the fluid,and use Fluent software to simulate the temperature field of the AZ31 B magnesium alloy melt in the casting zone.By comparing the simulation results of the three scenarios,the influence law of the designed cooling water volume adjustment sleeve on the cooling strength of the casting roll will be obtained,which will provide an important reference for on-site production.