JPH03210954A - Method for controlling spray water in continuous casting equipment - Google Patents

Abstract

PURPOSE:To uniformly control surface temp. on a cast slab at the time of unsteady casting by holding larger time delay as farther the zone from a mold and setting spray cooling water flow rate at each zone corresponding to casting velocity. CONSTITUTION:Molten metal is poured into the mold 11 and cooled, and the cast slab 12 is taken out through an arc roller apron part 13 and horizontal drawing-out straightening part 14. Then, to the casting velocity Vc actually measured with a casting velocity detector 21, the different prescribed delay time is given for each of plural zones 15-1, 15-2,... with a delay circuit 22 and converted to supplying flow rate QSV of the spray cooling water with a converter 23. This supplying flow rate QSV is multiplied by the prescribed factor K stored in a data resister 25 through a factor circuit 24 to obtain a supplying flow rate KQSV at outputted terminal 26 and flow rate control valves 17-1, 17-2,... and flow rate meters 18-1, 18-2,... are controlled with this value. By this method, uneven cooling for the cast slab 12, at the time of unsteady casting, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a spray water control method in continuous casting equipment, and particularly to a cascade control method for setting the spray water flow rate to a value corresponding to the measured casting speed.

(Prior art) In conventional continuous casting equipment, molten metal is generally poured into a mold from a tundish, a slab is pulled out from the mold while the mold is cooled, and the slab is cast in multiple zones. A preset amount of spray cooling water was supplied from a nozzle according to the casting speed for cooling, and slabs were continuously cast.

(Problems to be Solved by the Invention) By the way, in such conventional continuous casting equipment, during unsteady pouring such as when the pouring speed fluctuates (or when pouring the front or rear end of the slab), the slab non-uniform cooling of
In particular, supercooling could occur. In order to prevent such non-uniform temperature distribution of the slab, conventionally, a process computer is used to solve a heat transfer equation to determine the amount of water to be sprayed for each zone to obtain a predetermined slab surface temperature.

This control method is usually called dynamic spray control. The calculation by this process computer is 10~
This needs to be done every 20 seconds, but solving the heat transfer equation requires large-scale software and expensive hardware.

On the other hand, there is a method called cascade control as a method other than dynamics bray control. In this method, the set value Qsv of the amount of spray water is determined in accordance with the VcQsv curve shown in FIG. 4 in accordance with the actually measured casting speed Vc. This Vc-Qsv curve is determined in advance for each control loop and for each steel type.

However, in this method, when the measured pouring speed Vc suddenly increases, the set value Qsv of the amount of spray water also increases immediately, causing overcooling of the slab.

Therefore, it is an object of the present invention to provide a spray water control method in continuous casting equipment that can prevent non-uniform cooling of slabs, especially supercooling, which occurs during unsteady pouring such as when the pouring speed fluctuates. This is the purpose.

(Means for Solving the Problems) According to the present invention, molten metal is poured into a mold from a tundish, a slab is pulled out from the mold while cooling the mold, and the slab is passed through nozzles provided in each of a plurality of zones. In a spray water control method in continuous casting equipment that supplies spray cooling water at a flow rate set in accordance with the casting speed for cooling, the setting of the spray cooling water flow rate is different for each zone, and the setting of the spray cooling water flow rate is different for each zone, and the spray cooling water flow rate is different for each zone. There is obtained a spray water control method in continuous casting equipment, characterized in that the spray cooling water flow rate is set to a value corresponding to the casting speed with a time delay that becomes longer as the casting speed increases.

Further, according to the present invention, molten metal is poured into a mold from a pool, a slab is pulled out from the mold while cooling the mold, and the slab is poured through nozzles provided in each of a plurality of zones in accordance with the casting speed. In a spray water control method in continuous casting equipment that supplies and cools spray cooling water at a set flow rate, the setting of the spray cooling water flow rate is different for each zone, and has a time delay that becomes longer as the zone is farther from the mold. In addition, the spray cooling water flow rate is set to a value corresponding to the casting speed, and a time delay is provided for the tip or rear end of the slab, which becomes longer as the zone is farther from the mold. A spray water control method in continuous casting equipment is obtained, which is characterized in that the value corresponding to the set casting speed is multiplied by a coefficient greater than 0 and smaller than 1.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a part of continuous casting equipment to which the present invention is applied. Molten metal is poured into the mold 11 from a hot water pool (not shown). The mold 11 is cooled, and the slab 12 is pulled out from the mold, passes through an arcuate roller apron section 13 where a large number of rollers are arranged, and is supplied to a horizontal drawing straightening section 14 where a large number of rollers are also arranged. The arc roller apron part 13 and the horizontal pull-out correction part 14 have a plurality of zones 15-1.15-2.15.
It is divided into -3... At least one of the plurality of rollers in each zone acts as a drive roller, each drive roller being coupled to an electric motor (not shown). Each zone 15-1, 15-2, 15-3... has a nozzle for supplying spray water] 6-1.16-2.16
-3... are provided, each with a flow rate control valve 17-1.
．． 17-2.17-3... and flowmeter 18-1.1
Spray water is supplied via 8-2.183...

Figure 2 shows the spray cooling water supply mQsv in Figure 1.
FIG. 2 is a block diagram showing a setting method according to the present invention. The measured casting speed Vc, which is the output of the casting speed detector 21, is given a predetermined delay time T by a delay circuit 22. The output of the delay circuit 22 is supplied to a converter 23 that converts the measured casting speed (Vc) into a spray cooling water supply flow rate (Qsv),
A feed stream HQ S V is available at its output. This supply flow HQsv is supplied to the data register 25 in the coefficient circuit 24.
is multiplied by a predetermined coefficient K stored in , and the flow rate KQSV of cooling water supplied to the output terminal 26 is obtained. This feed stream Q
Depending on the value of KQsv, the flow rate control valve 17-1 in FIG.
．． 17-2.17-3... and flowmeter 18-1.1
8-2, 18-3... are controlled.

The delay time T given by the delay circuit 22 differs for each of the plurality of zones in which the slab 12 moves, and is set as follows.

In FIG. 1, each zone 15 from the mold 11 portion
-1.15-2.153... The distances to the rear ends are respectively gl, g2, Ω3.... The current casting speed is V
Assuming that the change occurs from l to V2, the delay times T, T2, T, . . . in the control loop of each zone are given as follows.

T + -i' l / V 2 T2 = N2 / V2 T3 - 413 / V2 As is clear from these relational expressions, the delay time in the control loop of each zone is longer in the lower zone, that is, in the zone far from the mold. I know that there is.

Next, in the coefficient circuit, the coefficient multiplied by the flow rate Qsv is 1 in steady state, but in unsteady state, for example, when the tip of the slab passes, it is X1, when the back end of the slab passes, it is X2, and when the tundish is replaced. are different from X3. Here, X1~X
3 is a value greater than 0 and less than 1, respectively.

The operation when the spray water control method of the present invention is applied to continuous casting equipment will be explained with reference to FIG.

When the casting speed changes from Vl to ■2 as shown in Figure 3 (A), the cooling water supply flow rate Qsv gradually changes from Ql with a delay time of T as shown in Figure 3 (C). Changes to Q2. Furthermore, since the delay time T is longer in the zone farther from the mold 11, excessive fluctuations in the slab surface temperature due to fluctuations in Vc can be prevented. Note that FIG. 3(B) shows changes in the supply flow rate Qsv of cooling water when no delay circuit is provided, and Qsv changes rapidly.

The passage of the front end of the slab and the rear end of the slab is tracked by a detector (not shown), and when these pass through each hole, Qsv is set to be smaller than the amount of water during steady pouring by a coefficient K. Therefore, overcooling of the front end of the slab and the rear end of the slab can also be prevented. When replacing the tundish, Qsv can be similarly reduced to prevent overcooling that occurs in normal cascade control.

(Effects of the Invention) According to the spray water control method in continuous casting equipment of the present invention described above, the surface temperature of the slab can be controlled uniformly even during unsteady casting by an instrumentation level controller without using a process computer. I can do something.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing a part of continuous casting equipment to which the present invention is applied, Fig. 2 is a block diagram showing a method of setting the spray cooling water supply fiiQsv in Fig. 1, and Fig. 3 is a block diagram showing the method of setting the spray cooling water supply fiiQsv in Fig. FIG. 4 is a graph showing the change in the cooling water supply amount Qsv when the spray water control method is applied. FIG. 4 is a graph showing the Vc-Qsv curve in the conventional cascade control method. DESCRIPTION OF SYMBOLS 11... Mold, 12... Slab, 13... Arc roller apron part, 14... Horizontal drawing correction part, 15
... Zone, 16 ... Nozzle, 17 ... Flow rate control valve, 18 ... Flow meter, 21 ... Casting speed detector, 2
2...Delay circuit, 23...Converter, 24...Coefficient circuit. Figure 2 Figure 2 0≦×1≦1

Claims (1)

[Claims] 1. Pour molten metal into a mold from a pool, pull out a slab from the mold while cooling the mold, and pour the slab through nozzles provided in each of a plurality of zones at a rate corresponding to the casting speed. In a spray water control method in continuous casting equipment that supplies and cools spray cooling water at a set flow rate, the setting of the spray cooling water flow rate is different for each zone, and has a time delay that becomes longer as the zone is farther from the mold. A spray water control method in continuous casting equipment, characterized in that the spray cooling water flow rate is set to a value corresponding to a casting speed. 2. Pour the molten metal into the mold from the pool, pull out the slab from the mold while cooling the mold, and spray the slab with a flow rate set according to the casting speed from nozzles provided in each of multiple zones. In a spray water control method in continuous casting equipment that supplies and cools cooling water, the setting of the spray cooling water flow rate is different for each zone, and the casting speed is controlled by giving a time delay that becomes longer in zones farther from the mold. The spray cooling water flow rate is set to a value corresponding to the flow rate of the spray cooling water, and a time delay is further set for the tip or rear end of the slab so that the zone farther from the mold has a longer time delay. A spray water control method in continuous casting equipment, characterized in that the value corresponding to the speed is multiplied by a coefficient greater than 0 and smaller than 1.