Research On Secondary Cooling Of Billet For ROKOP Continuous Casting Machine Of Chuanwei Irom & Steel Group Co.

The main work in this paper is solving the questions of internal cracks (between center and surface of the billet) at high casting speed in No.1 ROKOP continuous casting machine of Chuanwei Iron and Steel Group Company. The paper begins with reviewing the conditions of continuous casting techniques. In this paper, nozzles' cool and heat characters having been tested. Using the finite difference method and discretization of the differential eguation, the mathematical model of heat transfer for high speed ROKOP continuous casting machine is established. In the model, the varied time space is adopted, the heat transfer characters including spraying-water heat transfer and radiation of the ROKOP continuous casting machine are taken into account adequately, the effective specific cooling water and effective coefficients of spraying-water are adopted, and boundary conditions according to continuous casting are used. For the model, the software of good specialty and some common use is compiled.According to requires of metallurgical rules and results simulated by computer, the original structures of two segments of secondary cooling zone with length of 1.647m are not believe to adapt high speed casting, and the secondary cooling zone prolonged with 5 segments of 3.500m is put forward. By calculation, the new secondary cooling systems of static model adapted high casting speed of No.1 ROKOP continuous casting machine of Chuanwei Iron and Steel Group Company are got, and the temperature fields of billet, the parameters of solidification, the relations between casting temperature and maximum casting speed etc. are also got.The secondary cooling systems of the original structures are simulated according to equal specific cooling water. By calculation, the billet surface temperature is about 600℃ to 700℃ in the secondary cooling zone, and reascends about 500℃ to 600℃ beyond the secondary cooling zone at higher casting speed, which is the direct reason for the internal cracks. While for the structures of 5 segments, the billet surface temperature is about 800℃ to 900℃ in the secondary cooling zone and reascends about 200℃ beyond the secondary cooling zone. On the mean time, the dynamic mathematical model and dynamic calculation of cooling water of secondary cooling zone is studied, and the method adopted for the calculation of cooling water is according to the effective casting speed and modifiedeffective casting speed. The method for the calculation of cooling water is per 100mm billet is yield and the calculation is taken. From the results simulated by the computer, the billet surface temperature fluctuates smoothly and limitedly while the casting speed varies normally or acutely. The results make ground for Chuanwei Iron and Steel Group Company to adopt dynamic model for secondary cooling zone in the future.The fact proves, using the studied results the steady casting speed of No.1 continuous casting machine of Chuanwei Iron and Steel Group Company is 3.0m per minute and maximal casting speed can reach 3.4m per minute, the internal cracks of the billet disappear, the production increases greatly and the high efficient of the continuous machine is realized. The results of the studies also give direction for high efficient reformation of so many ROKOP continuous casting machine in nation...