| Ladle teeming system is an important production part which ensures the continuous casting runs smoothly.The new electromagnetic teeming technology uses on induction heating coil set at the bottom of ladle to quickly melt Fe-C alloy which has similar or identical component with melted steel to replaces the traditional drainage sand to achieve auto-teeming for the ladle.Compared with the traditional teeming methods,electromagnetic teeming technology not only enables rate of auto-teeming up to 100%,but also avoid the contamination of the liquid steel and the environment brought by drainage sand,thus enhancing the enterprise,market competitiveness.Electromagnetic system requires the induction heating coil set at the bottom of the ladle to melt the Fe-C alloy filled in the nozzle.However,the working condition at the bottom of the large ladle used in actual production is relatively more severe,common induction heating coil cannot satisfy the performance requirement.In order to find an induction heating coil that can be used in industrial production and electromagnetic teeming system,the component of the coil is designed and raw material is prepared at first in this paper.Then the coil structure is improved and coil processing is finished.Through thermal simulation experiment preliminary analyzes the heating effect of the new coil.Then electromagnetic steel technical modification is done for a certain steel mill production of 80t ladle and on this basis online test of coil is completed,meantime heating effect of the coil is observed at meantime.At last,the coil system is optimized according to the online test results.(1)Compared to the material of common coil and component in similar working environment,Cu-Cr-Zr ternary alloy was selected as the raw material for the coil.With reference to the phase diagram and the most commonly used values of the alloy composition,electromagnetic teeming system coil is designed with a target component of Cu-0.4Cr-0.2Zr.According to the composition of the material,through vacuum casting and heat treatment the coil material is obtained in a certain factory.The composition and performance measurement meet the design requirement through measuring.(2)According to the heating effect,ambient temperature and heat dissipation required by the electromagnetic teeming technology,the shape and size of the coil structures is designed(cross-sectional dimensions of 20×10×2 mm,inner diameter d=250 mm,height h=130 mm,the number of turns n=9).Reference to the current method of forming the oxygen-free copper coils and the rectangular of steel tubular,the new designed coil is successfully prepared for electromagnetic teeming system,and the coil material properties proved to meet the design requirements.(3)The new block brick(induction heating coil built-in)is prepared according to the requirements of the electromagnetic teeming system technology,and on this basis,high temperature thermal simulation experiment has been conducted.Results show that after 55 kW high power load 120 s,the sintered layer of Fe-C alloy is proved to be melt.The automatic steel-teeming can be realized at the thermal simulation experiment.(4)The bottom of the 80t ladle was modified to conduct industrial experiments.After placing the block brick equipped with coil,the power is on and the coil is gas-cooled when the ladle normally running to the casting position.The coil normally operates 5min when it was load on 20kW power.Then continue normal operation of ladle,the coil burnout and required to be optimized.(5)Lack of continuous work for high ambient temperature,the composition and heat treatment process are optimized for the coil material.The high-alloyed materials Cu-0.6Cr-0.2Zr thought solution treatment of 980℃×1h then water quenched,50%cold deformation and aging for 450℃/6h treatment,reaches the best performance and better than untreated alloy and Cu-0.4Cr-0.2Zr. |
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