Study Of Flow And Heat Transfer Phenomena And Its Influence On Deformation Of Blank And Mold For Beam Blank Continuous Casting Process

With the advertages of excellent mechanical properties and high efficiency,H-beam is porpular over the world.As a kind of near net shape continuous casting product,beam blank is the best rough material for rolling H-beam.However,because of the H shaped section structure,the beam blank has higher defect ratio than the conventional blanks.The fluid flow and heat transfer behaviors are the keys for getting stable casting process and high quality beam blanks.To investigat the influence of various factors on them deeply is very helpful and meaningful.This paper focus on the fluid flow and heat transfer in a beam blank continuous casting machine,which manufactures 435×320×9 0mm(BB1)and 500×3 60×102mm(BB2)two section beam blanks.The main work is listed in the followings:The four strand tundish was designed for two section sizes continuous casting beam blank molds,has the characteristic that the locations of inlet and outlets are asymmetric,besides each strand has two outlets.This study established a 1/3 scale physical model to test nine porous walls alternatives designed by L34 orthogonal method.The response time,mean residence time and inclusions collected weight were tested.TOPSIS comprehensive evaluation model based on variable coefficient method to determine the criteria coefficient were applied to analysis experiments data.The optimized porous wall alternative for various beam blank cases was presented.The tundish is heated by hot liquid steel at the continuous casting process,the location of the outlets change cause by the thermal expansion.This study showed that the displacement value of the outlets was up to 8mm.If this expansion cannot be eliminated at the design process,nozzle misregistration would happen in the mold.This paper studied the impacts of nozzle misregistration on the fluid flow field of the mold.The results showed that,when the nozzle offset up to 6mm,the fluid flow in the BB1 mold is totally different,and the distribution of solidified shell is less uniform.At BB2 case,the extreme nozzle offset is 7 mm.Full-protected pouring technology is the trend of continuous casting beam blank mold.This paper established a 1:1 water model,by through the tracer simulation,wave height measurement,inclusion simulation,to study the influence of nozzle number,nozzle designs,nozzle immersion depth on the fluid flow of the mold.Semi-protecting pouring is the most popular pouring technology in the small section size beam blank continuous cating mold,while there are few researches about it.Basic on the air entrapment quantity similarity,a full size water model was established.Meanwhile the three phases mathematic models were formulated in the frame of volume of fluid(VOF).Mathematic model results and physical model results got a reasonable match.Furthermore,basic on the performances in the area of air/steel interface,funnels inside wall shear stress and bubbles impacting depth,the effects of funnel immersion depth and funnel diameter on the fluid flow of the mold were discussed.A 3D model coupled the motel steel with channel copper mold was established.In this model,mold characteristic,shell thickness and fluid flow could be considered simultaneously.By summarizing previous researches,the air gap distributions between shell and mold hot face along circumference and casting directions were applied.The shell thickness results got reasonable matches with reported plant measurements.Furthermore,the effects of fluid flow on the solidification distribution were discussed.Also the 3D cooper mold temperature distribution and heat flux characteristic were predicted.A method for designning the mold taper was proposed,which takes into account the 3D forced flow and water channels characteristics of the mold.The deformation of the 21 characteristic points on the solidified shell surface and the mold hot surface were discussed in detail.The results showed that the section size and mechanics performance of steel have significant influences on the deformation.The taper curves of various parts of the mold copper plate were studied by combining the defects of the beam blank.435×320×9 0 mm and 500×3 60×102 mm beam blank continuous casting process were studied to enrich the research data of beam blank continuous casting.The results of the pilot plant test showed that the semi-protecting mold nozzle design can meet the demand of stable production.This research provides the theory evidences for getting high quality H beam blank,has high reference value and is innovative.