| 摘要 |
PURPOSE:To cause out of plate temp. on the overheating side and minimize out of plate temp. sections by estimating the optimum timing for changing the setting of furnace temp. from the direction of the changing the setting of the furnace temp. and the furnace operating conditions of that time, and commanding a change for the set value at that timing. CONSTITUTION:In the case of changing a steel strip from thick to thin one with a point P as a boundary in a continuous annealing furnace, the furnace temp. is lowered stepwise at around the point P. In this case, the setting of the furnace temp. is changed at the time when the point P arrives at the outlet of the furnace. During the response delay time T1, the succeeding steel strip is out of plate temp. in an overheating direction. In the case of changing the thickness of the steel strip from thin to thick one with the point P' as a boundary, the response delay time T1' of the furnace temp. is forecast, and the set value of the furnace temp. is changed before the T1' time when the point P' arrives at the furnace inlet. In this case, the part corresponding to the T1' time of the tail end of the preceding steel strip is out of plate temp. in a heating direction. In this case, the quantity of heat that the steel plate to be changed obtains is calculated, and flow rate of combustion of the furnace is determined. Thence, the change rate of the combustion rate of the ratio of the change rate of the combustion rate and the difference between the upper, lower limit combustion rates and the combustion rate before the change is determined and the time T1' is estimated from this. |
