Study On The Temperature Field And Stress Field Of A New Type Of Cooling Roller For Slab Continuous Casting Secondary Cooling

In the process of continuous casting,the size and distribution uniformity of billet surface temperature at different locations in the secondary cooling zone have important effects on the final product quality.The temperature control of secondary cooling zone is very important for the continuous casting production of certain steel types such as medium micro alloy steel and high strength steel.Because this kind of steel usually requires higher surface temperature of billet(especially the straightening area)to avoid the billet crack defects and improve the product quality.Therefore,in order to obtain the surface temperature required for production,the cooling water nozzle at the corresponding location of the secondary cooling zone is closed,which is called "dry cooling".Under dry cooling conditions,due to the lack of water and steam cooling,the surface temperature of the cooling roller is relatively high,and the operating conditions are even worse.In order to improve the service life of the cooling roller under the condition of "dry cooling" and ensure the good heat transfer effect of the cooling roller,it is necessary to develop a new cooling roller and carry out relevant technical research.At present,the research on roll of continuous casting machine mainly focuses on the structural design,material research and development,bearing application,seal lubrication,etc.Among them,the design of cooling roller structure is often the comprehensive application of all other technologies,which plays an important role in improving the service life of cooling roller.At present,the research on continuous casting dry cooling is still in the exploration and development stage,and the main research method is numerical simulation.Therefore,in this paper,the mathematical model of the new cooling roller in slab continuous casting dry cooling process is established,the heat transfer and stress between the cooling roller and the slab are calculated by numerical simulation method,and the optimal process parameters are obtained,which is of great significance for guiding the actual production process.The main research work and conclusions are as follows:(1)Established based on the slab continuous casting dry cooling new cooling roll three-dimensional heat transfer mathematical model,the simulation calculation for the temperature field distribution of the new-type cooling roller,new type of cooling roll through the design of the internal structure improves the cooling effect,accelerate the heat transfer,improved the thermal stress distribution inside the cooling roller,reduces the thermal fatigue crack affect the service life of the cooling roll.New stress distribution and temperature field distribution of the cooling roller is similar to the change law of equivalent stress,equivalent strain and deformation is small,the maximum equivalent stress appears in the ends of the roll,at 264.63 MPa,less than the yield stress of the roll material 624 MPa,didn't meet the conditions of producing thermal fatigue,a longer service life of the new cooling roll.(2)The cooling roller temperature field under different structures was compared and analyzed,and it was found that the cooling effect of the new cooling roller was better than that of the ordinary central water supply roller.By comparing the temperature field of the cooling roller under different working conditions,it can be seen that to increase the drawing speed as much as possible without leakage can effectively inhibit the generation of surface cracks on the cooling roller and thus improve the service life of the cooling roller.The optimal flow rate of cooling water through the cooling roller is determined,that is,the cooling effect is best when the flow rate is 3m/s.(3)According to the three dimensional temperature field calculation results,optimize the new cooling roller structure,including the different distances from the roll surface cooling channel holes,cooling roll cooling channel different aperture size,cooling roll cooling passage hole number distribution under the condition of numerical simulation,according to the optimization of the accurate,when the structure of the new cooling roll for weeks to the hole diameter of 20 mm,25 mm distance from the roll surface,hole number distribution for 10 optimization effect is best.