JPH0581646B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention provides a temperature control method and apparatus for controlling the temperature of the metal strip, which is installed in a continuous annealing facility that continuously processes metal strips. Regarding.

<Prior art> As shown in Fig. 4, a continuous annealing facility for metal strips is usually equipped with a preheating zone A, a heating zone B, and a cooling zone C. It is preheated in tropical zone A, heated to a specified temperature in heating zone B, held for a prescribed period of time, and cooled in cooling zone C. In this continuous annealing facility, various metal strips are processed one after another in succession, and the leading end of the next metal strip to be processed is connected to the trailing end of the preceding metal strip by welding.
It is processed without interruption. There are cases where the preceding metal strip and the subsequent metal strip have different thicknesses, and in that case, the following problems occur.

That is, it is preceded by a thick (e.g. 1mm thick) metal strip, followed by a thinner (e.g. 0.6mm thick) metal strip.
When subsequent strips are connected and processed, the processing conditions, such as the temperature of each part of the continuous annealing facility and the threading speed, must be maintained at the conditions required for the preceding thick metal strip until the processing of that metal strip is completed. , as soon as the processing of the preceding strip is completed, the processing conditions are changed to the processing conditions of the thin following strip.
It takes a considerable amount of time for the temperature distribution etc. throughout the continuous annealing facility to settle down to a point suitable for thin metal strips, during which time subsequent thin metal strips are over-annealed over a considerable length. It becomes a thing.

Therefore, as shown in FIG. 4, the heating zone B is divided into a first heating zone 18 and a second heating body 19.
A temperature control device T is placed between these two heating zones 18 and 19, and when the thickness of the metal strip S to be processed changes, this temperature control device T keeps the temperature conditions of the entire continuous annealing facility as short as possible. In time, the necessary conditions for the subsequent metal strip S are established.

As shown in FIG. 5, in the temperature control furnace 1 constituting the temperature control device T, there are slit-shaped nozzles 3 facing both sides of the passed metal strip S.
A plenum chamber 2 is provided.
The plenum chamber 2 is equipped with a blowing duct 4 for blowing gas for temperature adjustment, and the temperature adjusting furnace 1 is equipped with a recovery duct 5 for recovering the gas blown into it, and these ducts are connected to a connecting duct. 6, it is connected to a gas temperature controller 7 and a fan 8 to form a gas circulation path. This gas circulation path is a set of two systems corresponding to both sides of the metal strip S, and a plurality of sets are usually installed in the temperature control furnace 1. Note that in FIG. 5, only one set is shown for the sake of simplicity.

According to a continuous annealing facility having such a temperature control device T, when the metal strip S to be processed changes from thick to thin,
When the connection between the two passes through the inlet of the temperature control furnace 1, the operation of the fan 8 and the gas temperature control machine 7 is started, and the non-oxidizing air gas in the furnace is used as a low-temperature cooling gas to be supplied from the nozzle 3 to the plate. It is sprayed onto both sides of the thin metal strip S to lower the temperature of the thin metal strip S, and then reheated to a specified temperature in the subsequent second heating zone 19. After the leading thick metal strip S has passed through the cooling zone C and its annealing has been completed, the temperature control furnace 1 stops controlling the temperature by blowing out gas, and functions simply as a passage for the metal strip S. Normally, for a thin metal strip S, the conditions are set by increasing the threading speed compared to a thick metal strip S.

In FIG. 4, 17 is a preheating furnace that constitutes a preheating zone A that precedes the heating zone B, and 20 and 21 are a first cooling zone and a second cooling zone that constitute a cooling zone C, respectively.

<Problems to be Solved by the Invention> This temperature control device T does not perform cooling operation by blowing cooling gas when metal strips S of the same thickness are passed for a long time, but merely It serves as a passageway for Strip S. Therefore, the gas in the furnace remains stagnant, and its gas temperature is approximately equal to the temperature of the metal strip S passing through it, which is usually 700-800°C.

When the thickness of the metal strip S to be processed changes, the operation of the fan 8 and gas temperature controller 7 is started when the connection point where the front and rear metal strips S are welded enters the temperature control furnace 1. Cooling of the metal strip S is started by blowing out low temperature cooling gas from the nozzle 3 of the plenum chamber 2.

The temperature of the gas in the temperature control furnace 1 before the start of cooling is
Assuming that the temperature inside the furnace is 700℃ and the gas pressure in the furnace is +100mm water column, the pressure inside the furnace when the mass of the gas inside the furnace is cooled to 200℃ without changing is simply calculated as follows.

(10332 + 100) x 200 + 273 / 700 + 273 = 5071 (mm water column) Here, 10332 is the equivalent value of 1 atm water column 5071 - 10332 = -5261 (mm water column) In reality, during cooling, from the gas circulation path etc. Because gas flows in and out, it will not be such an extreme negative pressure, but it will still be -1000~-
Negative pressure of about 2000 mm of water column may occur. When such a large negative pressure is generated, air that oxidizes the metal strip S is easily sucked into the temperature control furnace 1 from the entrance and exit of the metal strip S, for example, and this is one of the causes of quality deterioration of the metal strip S. .

The present invention solves this problem.In a continuous annealing facility for metal strips, when the thickness of the metal strip changes, the width of the change in the pressure inside the temperature control furnace is reduced, and air is sucked into the furnace. An object of the present invention is to provide a temperature control method and device that can prevent this.

<Means for Solving the Problem> The temperature control method for a metal strip according to the present invention involves blowing gas from a nozzle in a plenum chamber onto both sides of the metal strip to be passed through the metal strip to adjust the temperature of the metal strip. In a method for controlling the temperature of a metal strip in a temperature control device of a continuous annealing facility having a furnace, before blowing out gas from a nozzle to start cooling the metal strip, the metal strip is passed through a furnace temperature control bypass without passing through a plenum chamber. Gas is introduced into the temperature controlled furnace to pre-cool the inside of the furnace, and when the metal strip needs to be cooled, the gas is blown onto the metal strip through a nozzle in the plenum chamber to cool the metal strip. It is characterized by starting the cooling of the strip.

Further, the temperature control device for metal strip according to the present invention is a continuous annealing facility having a temperature control furnace that controls the temperature of the metal strip by blowing gas from a nozzle of a plenum chamber onto both sides of the metal strip being passed. In a metal strip temperature control device, a blow duct for blowing gas into the plenum chamber is attached to the plenum chamber via a damper, a recovery duct for recovering gas from the temperature control furnace is attached to the temperature control furnace via a damper, and the blow duct and the blow duct are attached to the temperature control furnace via a damper. The recovery duct is connected by a damper and a bypass duct, and the furnace temperature control bypass and damper are further provided from the blow duct to the temperature control furnace without passing through a plenum chamber.

<Operation> The inside of the temperature control furnace is cooled in advance, and then cooling gas is blown out from the nozzle of the plenum chamber inside the temperature control furnace to start cooling the metal strip. Since the temperature drop in the temperature-controlled furnace is small and, as a result, the negative pressure generated is small, almost no air is sucked into the furnace.

<Example> Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram simply showing a temperature control device T of the present invention. Further, FIG. 2 is a diagram showing the damper operation when pre-cooling the inside of the temperature-controlled furnace 1 of the present invention, and FIG. It is a figure which shows damper operation at the time of cooling.

As shown in FIG. 1, a temperature-controlled furnace 1 according to the present invention has a metal strip S passed through it, and a plenum chamber 2 having gas blowing nozzles 3 is installed facing both sides of the metal strip S. ing. Although only one set of plenum chamber 2 is shown in this diagram for ease of explanation,
Multiple sets are installed in an actual furnace.

A blowing duct 4 for blowing gas is attached to each plenum chamber 2 via a damper 10, and a recovery duct 5 for recovering and circulating and reusing gas is attached to the temperature control furnace 1 via a damper 11. It is attached through. Collection duct 5
The gas from the gas temperature controller 7, the communication duct 6, and the fan 8 are sent to the blowing duct 4 again. Also blowing duct 4
and the recovery duct 5 is connected to the damper 12 and the bypass duct 9.
are connected by Further, a furnace temperature control bypass 13 and a damper 14 are installed from the blow duct 4 to the temperature control furnace 1 without passing through the plenum chamber 2. The furnace temperature control bypass 13 is attached to the temperature control furnace 1 behind the plenum chamber 2 in order to reduce the influence on the metal strip S when precooling the inside of the furnace. A gas supply port 15 and a damper 16 are attached to the communication duct 6.

Before blowing out gas from the plenum chamber 2 and starting cooling the metal strip S, first, the dampers 10, 11, 14 and 15 of the temperature control device T are closed, the damper 12 is opened, and the fan 8 is started. When the fan 8 reaches steady rotation, the gas temperature controller 7 starts operating. At this time, if necessary, the damper 16 is opened to replenish the gas. In this way, the gas temperature is adjusted to a predetermined value while performing the bypass circulation operation of the gas through the bypass 9. When the gas temperature reaches a predetermined value, the damper 14 is opened and cooling of the temperature control furnace 1 is started. The state of the damper at this time is shown in FIG. At this time, damper 1
It is preferable to open the furnace slightly and circulate some of the gas through the furnace temperature adjustment bypass 13, the temperature adjustment furnace 1, and the recovery duct 5.

When the inside of the temperature control furnace 1 reaches a predetermined temperature and the connection part of the metal strip S reaches the temperature control furnace 1, each damper 10, 11,
12, 14 and 16. By doing this, the cooling gas will now flow into plenum chamber 2.
The metal strip S is blown from the nozzle 3 of the metal strip S, and the metal strip S is cooled. In this way, since the inside of the temperature control furnace 1 has been cooled to a predetermined temperature in advance, the range of temperature drop when the metal strip S starts cooling is small, and therefore the pressure inside the furnace 1 does not drop as much, and air is not sucked. do not have.

When pre-cooling the inside of the temperature control furnace 1, as mentioned above, the gas for cooling the metal strip S is circulated in advance through the bypass circulation path, and a part of the gas is divided and used for cooling the inside of the furnace. Alternatively, a gas different from the gas for cooling the metal strip S may be used to cool the inside of the temperature control furnace 1 through a different route.

<Effects of the Invention> According to the method and apparatus for controlling the temperature of a metal strip according to the present invention, by cooling the temperature control furnace to a predetermined temperature in advance, the temperature inside the furnace at the start of cooling of the metal strip can be adjusted. Reduce the drop width,
In turn, it is possible to reduce the drop in the furnace internal pressure, which prevents air from being sucked into the temperature-controlled furnace at that time, and prevents deterioration in product quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a temperature control device illustrating an embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams illustrating a temperature control method using the temperature control device shown in FIG. 1, and FIG. Conceptual diagram of continuous annealing facility, and 5th
The figure is a schematic diagram of a conventional temperature control device. In the drawing, S is a metal strip, T is a temperature control device, 1 is a temperature control furnace, 2 is a plenum chamber, 3
is a nozzle, 4 is a blow duct, 5 is a recovery duct,
7 is a gas temperature controller, 8 is a fan, 10, 11, 1
2, 14 and 16 are dampers, and 13 is a furnace temperature control bypass.

Claims (1)

[Claims] 1. A temperature control device for a continuous annealing facility, which has a temperature control furnace that controls the temperature of the metal strip by blowing gas from a nozzle in a plenum chamber onto both sides of the metal strip being threaded. In the strip temperature control method, before the gas is blown out from the nozzle to start cooling the metal strip, the gas is introduced into the temperature control furnace through the furnace temperature control bypass without passing through the plenum chamber. The metal strip is characterized in that the inside of the furnace is cooled, and when the metal strip needs to be cooled, gas is blown onto the metal strip from a nozzle in a plenum chamber to start cooling the metal strip. How to adjust the temperature. 2. In a temperature control device for a metal strip in a continuous annealing facility, which has a temperature control furnace that controls the temperature of the metal strip by blowing gas from a nozzle in the plenum chamber onto both sides of the metal strip being threaded, the gas is injected into the plenum chamber. A blowing duct for blowing is attached to the plenum chamber via a damper, a recovery duct for recovering gas from the temperature regulating furnace is attached to the temperature regulating furnace via a damper, the blowing duct and recovery duct are connected by a damper and a bypass duct, and further blowing is performed. A metal strip temperature control device characterized in that a furnace temperature control bypass and damper are provided from a duct to a temperature control furnace without passing through a plenum chamber.