| 摘要 |
A method of determining the profile of the crystallizer case of for high-speed continuous casting of steel in the form of square or rectangular pipe, which has a profile close to the natural outlines of ingot during hardening, at which the shape of profile is calculated during formation of ingot for the specific groups of steel grades as for the content of carbon, the coefficient of shrinkage in the solid state and the time of crystallization of ingot in the crystallizer case. The ingot in the crystallizer case of the real process of crystallization is divided into the specific number of crosssections and with the help of the computer, using the equation of unsteady thermal conductivity with boundary conditions of cooling for given steel grade with known thermal and physical parameters, the crystallization time and the temperature of liquid steel of real process of crystallization the temperature fields of hardening for each cross section of ingot are drawn up and in case of divergence of the calculated temperature of the middle part of the face surface of the ingot T for the last cross section with the temperature of the middle part of the face surface of ingot at the crystallizeroutlet in the real conditions of crystallization for this grade of steel the boundary conditions of cooling are modified up to the convergence of mentioned temperatures. Then by way of calculations the crystallization time of ingot is decreased several times in the case and after each decrease of time the temperature of the face surface T in each mentioned cross section of ingot in the crystallizer case and the thickness of hardening shell are determined. The time of crystallization is decreased up to moment of time , at which the thickness of shell in the last cross section will reach the maximum permissible value of mechanical strength and according to the obtained temperatures of the surfaces of the middle of face of ingot T, deg. C, in each of its cross sections during this time of crystallization , after which the final temperature of hardening of the shell TKIH, deg. C is determined in each of its cross sections.
|
