JPS58125351A - Control of cooling of cast product in continuous casting installation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The purpose of the present invention is to divide a casting into basic pieces based on assumptions, to periodically calculate the amount of water to be injected into six pieces as a function of the material age, and to In order to determine the target value of the water supply l to the compartments, integrating the water volume calculated for all pieces in each compartment of the secondary cooling zone and determining the water supply volume to each compartment by the control device. An object of the present invention is to provide a cooling control method for a cast product in a continuous casting facility, which includes a step of maintaining each target value equal to the target value. In order to calculate the amount of water to be sprayed on the 6 pieces, the material order of the pieces is 1! The curve showing the change in said values as Ia C = f (t) and T =
Using g (t), the amount of heat to be extracted from the corresponding piece is determined, the heat exchange coefficient is calculated, and the specific water content for the iron piece is determined from said values by means of a curve representing the relationship between the two core values.

According to the method of the invention, the curve c = r ( t
) by moving parallel to the axis representing time, the amount of heat extracted from the mold can be taken into account when calculating the amount of water. If the surface temperature of the cast product at the exit of the mold can be calculated from the iron metal using a curve created by calculations made based on assumptions in advance, when correcting the curve T = (1) by the method of the present invention, Considering the amount of heat extracted from the mold # To determine the amount of heat extracted from the mold for the six pieces of the casting, the flow rate and temperature rise of the mold cooling water are continuously measured. Similarly, the foregoing may be determined by experimentally obtained data and hypothetical calculations stored in the memory of the combiator.

Due to different reasons (effect of lubricating powder, casting shrinkage of solidified metal, etc.),
The profile of the heat flow extracted by the mold may be higher at the top than at the bottom, so that when measuring the total amount of heat extracted from the mold, all parameters of the casting, especially the mold cooling water flow k and the temperature and demolding rate remain constant throughout the residence of the corresponding piece in the mold.
It is possible to send accurate information regarding the amount of mold release heat for 6 pieces.

Generally, but not always, 6 pieces of castings are ll
Regarding the amount of heat when molding l11, and the temperature from the amount of heat, J
[Inaccurate information is obtained regarding the surface temperature of the casting at the exit of the mold when calculating.]

An object of the present invention is to improve the cage method of the present invention, whereby each elemental piece of a cast product can It is now possible to more accurately determine the thermal behavior of the iron piece as it passes through.

The method which constitutes the object of the invention comprises the steps of distributing the total amount of heat extracted from the mold from the top to the bottom of the mold according to predetermined laws, and the distribution of the iron pieces as a function of the position each elemental piece of the casting occupies in the mold. The step of periodically calculating the amount of heat released from the mold and calculating the total amount of heat extracted from the mold for the six pieces at the outlet of the mold from the calculated value obtained by this, and the step of calculating the age of the six pieces. using said calculated value when calculating the amount of water to be injected onto the iron piece during the stay of the corresponding piece in the secondary cooling zone in order to correct by one the curve representing the change in demolding heat as . The total heat value at the time of demolding of the six pieces calculated according to the method of the present invention, which is characterized by including: The values obtained in this way are used in accordance with the main method of the invention to correct the curves showing the variation of the surface temperature as a function of the age of the six pieces.

The distribution law for the total amount of heat extracted from the mold is developed by experimental measurements.

In particular, the effective part of the mold can be divided into multiple zones.
The total amount of heat extracted by the mold can then be distributed to each zone. In this case, the number of bands is, for example, 2 to 20.
It is. The number and length of the zones and the proportion of the total amount of heat to be distributed to each zone are determined by considering the degree of progression of thermal efficiency from the top to the bottom of the mold, and are estimated from experiments and measurements conducted in advance. For each calculation, the amount of heat extracted from one zone of the mold is distributed among the other base materials of the casting in that zone.

This distribution is carried out in each zone in proportion to the length of the strip.

Other features and advantages of the invention will be explained in more detail below with reference to the accompanying drawings, which illustrate embodiments of the invention.

The continuous copper casting equipment shown schematically in Figure 1 mainly consists of:
It includes a mold 10, a corset 12 for guide rollers, a straightening roll 14, and injection or spray nozzles or tubes arranged in groups in each section, and all the nozzles or tubes provided in the same section have a partition multi-valve 16. Branched parallel to the water supply pipe, the opening of the water valve is controlled by the control device 18 to maintain the water supply amount equal to the target flow rate determined by the combination gourd 2o. The nozzles or tubes can be placed around the entire circumference of the casting or only on the wide side, as in the case of rods with rectangular cross section.

Manual controls and devices are provided to distribute the total water supply to the four-compartment between the other nozzles or tubes in accordance with the position of the nozzle or tube.

The device according to the invention includes: various measuring devices for obtaining information transmitted to the computer 2o;

That is, a high temperature needle 22 for measuring the temperature of the molten metal in the distributor 24, a measuring meter 26 for measuring the temperature of mold cooling water at the inlet and outlet of the mold, and a meter 26 for measuring the temperature of mold cooling water at the mold inlet and outlet. A flow cap needle 28 for measuring, an impulse generator 30 for measuring the separation velocity of the rod and calculating the material age of the rod element, and a measuring device for measuring the surface temperature of the rod near the correction point. It is a pyrometer 32 or the like.

From this information and data stored in the computer, the combiator determines at regular intervals target values for the amount of water supplied to the different compartments of the cooling device. This regular time interval is for example 1 to 50 seconds.

The principle of cooling control according to the method of the invention is to constantly develop the solidification state of the rod, regardless of the operating state of the casting machine. To this end, we apply the law of the variation of the amount of heat extracted by a kilogram of steel as a function of its residence time in the machine 0 := f (t) (FIG. 3).

This law is accompanied by the law of the change of surface temperature as a function of the time spent in the machine: T = g (t) (tic 2). These laws mainly depend on the steel quality, bar shape and demolding speed. In fact, bars of a given size are classified according to their steel quality and demolding speed.

All the above-mentioned tunes are determined by the sub-variant formula or by the exact values introduced to be stored in the computer. The data regarding the negative and bar dimensions are introduced into the combinator before each casting in order to make the selection of the corresponding curve spacing one-step process. The demolding speed is constantly determined by the impulse generator 30, and the combiator selects a curve spacing corresponding to the average speed determined from the measured values.

Depending on the chosen curve spacing, the combiator can seamlessly calculate from C and T the surface heat exchange coefficient , the specific water quantity q can be determined before being injected into the unit on the surface of the corresponding element.

The four edges may be single if the cooling zone is integrated, but if the zone is composed of various sections, the four edges may be formed by a plurality of valid different segments and curves. Good too.

A cough calculation can be performed, for example, every 10 seconds, dividing the bar into elements having the same length as the pieces stored during the time interval between two consecutive calculations. Therefore, the order number assigned to each of the six pieces at the same time as they are manufactured makes it possible to immediately recognize the material age and position within the machine.

By knowing the specific water amount q for each basic piece, it is possible to calculate the amount of water Q=qx8 to be injected onto the side surface S of the iron piece.

After calculating the amount of water to be injected to the six rods in the cooling zone for a predetermined period of time, the target value of the water supply amount for different sections of the cooling zone is calculated by integrating, and the calculated value is applied to each control device 18.
to communicate.

When using atomizing nozzles or tubes in which compressed air breaks up the injected water into very fine droplets, the total water volume in the secondary cooling zone is calculated and the total air volume to be used is determined from it; is carried out using a square formula or a curve that determines the mutual relationship between the flow rates of the two plants. A device is provided for manually controlling the distribution of the total amount of air supplied to the secondary cooling zone to each compartment.

In order to determine the amount of heat to be extracted from each elemental piece of the rod within the secondary cooling zone, the amount of heat actually extracted from the mold must be considered. For this purpose, a basic curve c =
We use r(t) (indicated by - in Figure 3), which has coordinates that correspond to the total time that the casting remains in the mold and the heat tct actually extracted from the mold, respectively. The general formula for this new curve is 0=f(
t-a)) is shown by the dotted line in FIG.

The surface temperature of the rod at the exit of the mold is calculated for every 6 pieces by means of a curve that is previously generated by simulation calculations and varies the temperature as a function of the amount of heat extracted from the mold. The curve is stored in the computer's memory. The temperature T/ is a curve T corresponding to the operating state of the machine.
= g (t) (M shown by the solid line in Figure 2) if different from the theoretical temperature 4, for example, at the outlet of the mold (~
By allowing a linear change in temperature from point 1t) to a predetermined point in the upper part of the cooling zone (the curve shown by the dotted line in FIG. Find the temperature of During the stay of the corresponding piece in the secondary cooling zone, the combiator uses said correction curve to determine the surface temperature which is taken into account in the calculation of the water flow target value.

For each calculation, the combiator 20 classifies the values obtained from the temperature and water flow values continuously measured by the temperature meter 26 and the flow meter 28 at the inlet and outlet of the cooling device of the mold or by a simulated calculation. From this arrangement, determine the total amount of heat extracted from the mold before performing the next calculation.

Next, by using the distribution curve of the amount of heat extracted from the mold, we determine the amount of release heat for each elementary piece in the mold m for the corresponding period, and calculate the amount of heat extracted from one of the six pieces. calculate. The curve 2WIW4 shown in FIG. 4 shows the amount of heat atLDf extracted from the metal in the mold through the mold wall as a function of the distance t to the free surface of the metal. It can be used for

In fact, the amount of heat extracted varies continuously from one end of the effective part of the mold to the other end, as shown by the curve shown in Figure 11g4. -A, the law of current distribution (curve 1115i indicated by the dotted line in Figure 4) may be used as shown schematically in Figure 4, and the effective part of the mold is divided into multiple zones (four in the illustrated example). The amount of heat can be maintained at a constant value in each zone.

In each calculation step, the elementary piece of the bar located at the outlet of the mold is investigated in more detail, and the material age of the iron piece and the heat extracted from the piece during its stay in the mold, and its surface. Calculate the temperature TIt.

Curve −〇 = f (t) is shifted to create the curve T as described above.
Use said value for each calculation to correct for = g (t).

By supplementing the main method of the present invention, it is possible to more accurately determine the amount of mold release heat for each elementary piece, thereby improving cooling control.

[Brief explanation of the drawing]

Figure M1 schematically shows the cooling side 94 arrangement for curved continuous f&- and cast rods according to the present invention. FIG. 2 shows the change in surface temperature of the bar as a function of time during its passage through the casting machine. Figure 3 is a curve C = f (t) showing the change in demolding heat per unit of the casting as a function of time as it moves from the free surface of the metal in the flask into the casting machine. . FIG. 4 shows the curved edge distribution of heat extracted from the mold. 18......Control device, 20......
··Computer.

Claims (2)

[Claims] (1) The step of dividing a cast product into basic pieces and the curve showing the change in size as a function of the age of the iron piece (C=f
(t), T=g(t)), the combiator (20) periodically determines the amount of heat to be extracted from the six pieces and its surface temperature, and the heat exchange coefficient is determined from the values determined as described above. a step of calculating the specific water amount for the corresponding section, a step of calculating the amount of water to be injected into the corresponding section, and a step of calculating the amount of water to be injected into the corresponding section, and a time period corresponding to each section of the cooling zone in order to determine the target value of the water amount in each section. as a function of wood age, including the step of integrating the amount of water calculated for all of the staying pieces and the step of ensuring that the amount of water supplied to each section is always equal to the IlI value of each section by means of a control device (18). The curve <a=rrt>> showing the change in the amount of heat to be extracted from the six pieces is the mold (1t
) before calculating the amount of water to be injected into each of the six pieces so that the pieces pass through a point whose coordinates are the total number of hours the piece stays in the isthmus and the amount of heat (Ot) extracted from the iron piece in the isthmus. 6 in the mold by moving parallel to the axis representing time.
In order to determine the amount of heat (Ot) to be extracted from the piece, the total amount of heat extracted from the mold is periodically determined, and the total amount of heat is calculated over the entire effective height of the mold according to a predetermined law. The amount of heat extracted from the six pieces in the mold at the corresponding moment is estimated from the foregoing, and the amount of heat extracted from the mold at the outlet of the mold is determined by summing the amounts of heat determined periodically during the stay of the iron pieces in the mold. A cooling control device for a cast product in continuous casting equipment, characterized in that the total amount of heat extracted from the mold is calculated for six pieces. (2) The total heat value of the six pieces extracted from the mold is used to determine the surface temperature of the iron piece at the exit of the mold, and the value thus obtained is 2. A method according to claim 1, characterized in that it is used for correcting a curve showing a change in temperature.