Development Of Characteristic Testing System Of Continuous Casting Nozzle And Simulation Software On Secondary Cooling Zone

Secondary cooling system has important influence on the quality of casting strand. To establish a proper secondary cooling system for continuous casting machine is a significant problem which urgently needs to be solved. It can not only achieve the requirement of strand cooling but also ensure the quality of casting strand. Nowadays, computer simulation is an important method to analyze the heat transfer of strand solidification in secondary cooling system research. Firstly,a new equipment for testing characteristic of secondary cooling nozzle was developed in this paper. Using the testing equipment water jet density and impacting pressure in different spraying position can be tested through nozzle moving and two settled sensor detecting. Testing process was controlled through computer manipulation, which had increased testing efficiency and precision. Cold state and thermal state characteristics of continuous casting nozzle were tested. Water jet density distribution and the relation between heat transfer coefficient and water density were obtained. It provided accurate boundary condition for computer simulation. Furthermore, computer simulation software which had been developed in our lab was improved. Water quantities calculation of secondary cooling zone was added in the simulation software. Based on amount of secondary cooling water in different casting speed calculated with simulation software, the relation between water quantities and casting speed was obtained through regress. With bending theory of beam and slab applied, a strain analysis model of continuous casting slab was established. The strain model can be used to calculate the distribution of bulging strain, unbending strain and roll misalignment strain at the solidifying front along the direction of casting speed. The strain distribution was calculated for 20g steel in the caster of Nangang. Through simulation the influence of casting speed, superheat and secondary cooling scheme on the strain had been analyzed. Calculation for unsteady state was came true in the simulation software. A method putting average speed as parameter in the assignment of secondary cooling water was adopted in the software. This method avoided sharp fluctuation of surface temperature as casting speed changed. The result of simulation showed that the method of water assignment putting average speed as parameter can meet the demand of slab cooling in the process of unsteady state.