连铸板坯凝固过程的鼓肚应变分析

Analysis on bulging strain of continuous casting slab during solidification

针对板坯连铸机铸坯的鼓肚变形问题,通过降低铸流两相界鼓肚应变以解决结晶器液面的波动问题,考虑辊子与铸流的接触弧长对鼓肚应变的影响,推导出辊子与铸流的接触弧长与鼓肚应变的关系式,得到辊子与铸流的接触弧长对鼓肚应变的解析解。通过推导辊子与铸流的接触弧长和鼓肚应变的关系式,量化其对鼓肚应变的影响程度。首先建立板坯连铸和凝固传热模型,以获得板坯冷却过程中板坯壳的生长。其次建立了改进的三维鼓肚有限元模型,根据实际连铸机的设备和工艺条件,计算板坯凝固过程中鼓肚变形量和鼓肚应变。最后,依据仿真结果得到零号扇形段的坯壳鼓肚变形状态,以及坯壳在两相界的应变规律。结果表明,当辊径每增加50 mm时,在同一位置处鼓肚应变会减小0.005%左右,因此增大辊径可有效增加辊子接触弧长,并且降低鼓肚应变,在0号段应选取辊径为250 mm,使得鼓肚应变最小。

In view of the bulging deformation of slab during continuous casting,in order to eliminate fluctuation of the mold liquid level by means of reducing bulging strain at the boundary of two phases of the casting stream,considering influence of contact arc length between roller and casting stream on the bulging strain,the relationship between contact arc length and the bulging strain is derived,and the analytical solution of contact arc length on the bulging strain is obtained.The relationship between the contact arc length and the bulge strain is deduced to quantify its influence on the bulge strain.Firstly,the heat transfer model of slab continuous casting and solidification is established to obtain the growth of slab shell during slab cooling.Secondly,an improved three-dimensional bulge finite element model is established to calculate the bulge deformation and bulge strain during slab solidification according to the actual equipment and process conditions of the continuous caster.Finally,based on the simulation results,the bulging deformation state of the shell and the strain law of the shell at the two-phase boundary are obtained.The results show that when roll diameter increases by 50 mm,the bulge strain at the same position will be decreased by about 0.005%.Therefore,increasing roll diameter can effectively increase contact arc length of the roller and then reduce the bulge strain.In section 0,the roll diameter of250 mm should be selected to minimize the bulge strain.