| The ladle-teeming system plays an important role ensuring the manufactory operations in the continuous casting of steel.The main mechanism of the electromagnetic induction controlled automatic steel-teeming method is using induction coil arranged in the nozzle brick to melt part or the whole of the new well-packing materials(i.e.Fe-C alloy with similar composition of the molten steel),which is the substitute of the conventional nozzle sand,in order to achieve smoothly automatic steel teeming.Compared to the traditional ladle-teeming method,the new method has a number of benefits,such as avoiding the pollution of the nozzle sand on the molten steel and environment,providing 100%free opening rate,increasing of cleanliness of molten steel,easing the passive situation that our country lacks chromium mineral resources,minimizing environmental pollution caused by the nozzle sand,reducing production cost for enterprises and enhancing economic benefits and market competitiveness of,enterprises.To apply the laboratory results of the new automated steel-teeming method in industrial production,this thesis presents the follows.Firstly,the industrial experiments and numerical simulation are employed to investigate two necessary conditions of the new system.One is the blocking effect of Fe-C alloy while the other is the Fe-C alloy melting effect of induction heating device used in the system.Both are based on the technological process of the ladle(110t)used in continuous casting while the design parameters which are suitable for the new system of the devices are obtained.Secondly,on the base of previous investigation,the system devices for the ladle(110t)used in continuous casting are manufactured.The system modification scheme is designed while the installation and adjustment of the system is done.In addition the reliability and feasibility of the system are evaluated using numerical and experimental methods.Finally,the preparatory works of industrial experiment of the new method have done successfully,and the success of the first step have done successfully.The main contributions in this study and industrial experiments are as follows:(1)The results of the industrial experiments of "sand-collection" and "steel-pour"show that,the blocking layer of the Fe-C alloy blocked the molten steel is formed under high temperature molten steel.The position of the bottom surface of the blocking layer could be effectively increased by adjusting the composition,size and shape of the Fe-C alloy.If the filler in the upper nozzle is cylindrical(diameter,2.0mm;tall,2.0mm)particles made of 10#steel,the position of the bottom surface of the blocking layer was 231mm.The thickness is 130mm.The distance between the top surface of the blocking layer and the top surface of the nozzle brick is 154mm,as could meet the demand of the coil installation.(2)The ladle-teeming process of a self-designed ladle(1.5t)with an electromagnetic induction controlled automatic steel-teeming system is investigated by applying experimental and numerical methods.The calculated results are consistent with experimental data and the correctness of the model is verified.Then,the coil working temperature is studied.The results show that the coil working temperature decreases from 1187OC to 467'C under the condition that there were insulating layers(the thickness:20mm,the conductivity:0.03W/(m*-C)on the top and both sides of the coil,and the coil could work safely in the high temperature nozzle brick.(3)The eflfect of the coil and power parameters on the teeming efficiency of the industrial ladle(1 1Ot)with the system is investigated,and the optimum parameters which are suitable for the system are obtained.The coil parameters:material,copper pipe;shape of copper pipe,rectangle(length,18mm;width:10mm,wall-thickness:2mm),coil radius:120mm,coil length:130mm,distance between top surface of coil and top surface of nozzle brick:150mm.The power parameters are current intensity:150A and frequency:16kHz.The parameters provide theoretical foundation for the design and manufacture of the system.(4)According to the parameters mentioned above,the electromagnetic induction controlled automatic steel-teeming system for the industrial ladle(110t)is manufactured.The minimum temperature at the position of the blocking layer is above 1543? after 120 seconds of operation of the system.Hence there is no doubt that the blocking could be melt smoothly.Then the feasibility of the system is verified.The thermal stability of the ladle(110t)with the system is consistent with traditional ladle with the materials such as ladle linings,ladle shell,insulating material,and coil.All meet their safety requirements while the reliability of the system is also verified.(5)Based on the technical requirements of the ladle-teeming used in continuous casting production of a steel plant and combined with technological features of the system,the modification scheme and process route of the system are designed on the basis of the traditional ladle.The system is modified and assembled in accordance with the scheme.Then,the reliability and feasibility of the system is examined by using the medium-test experiments.This part of work establishes the foundation for the industrial experiments and the technology extension of the new system. |
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