JPH024926A - Vertical continuous heat-treating furnace - Google Patents

Abstract

PURPOSE:To effectively isolate the respective atmospheric gases in the high- temp. zone and the low-temp. zone from each other by providing a communicating passage connecting the upper part of the high-temp. zone and the lower part of the low-temp. zone in the title vertical continuous heat-treating furnace. CONSTITUTION:Two partition walls 13 are provided between the heating zone 1 or soaking zone 2 and the cooling zone (cooling zone 3, etc.) to form a sealing tunnel 14. The tunnel 14 is connected to the high-temp. zone at the upper part and to the cooling zone at the lower part. Under such a constitution, a band steel S is conveyed by hearth rolls 9 and 9' from the high-temp. zone to the cooling zone through the tunnel 14. By this method, the infiltration of the respective atmospheres in the high-temp. zone and cooling zone into each other is effectively prevented, a unit requirement of fuel is reduced, the meandering of the band steel S is prevented, and heat buckling is obviated.

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a vertical continuous heat treatment furnace for IJ tubes,
In particular, it relates to a metal strip vertical continuous heat treatment furnace with a novel structure that can effectively isolate atmospheric gas in a high temperature zone from that in a low temperature zone.

(Prior Art) There are many types of vertical continuous heat treatment furnaces for metal strips, such as vertical continuous annealing furnaces for copper strips.
Shown in Figures a-d. Figure (a) is the most typical example, where ■ is a heating zone, 2 is a soaking zone, and 3 is a cooling zone. There is also a type of furnace in which the soaking zone 2 is omitted, as shown in FIG. 2(b). Furthermore, there are models in which the cooling zone 3 is divided into a cooling zone 4 and a rapid cooling zone 5 as shown in FIG.
There is also a type that is divided into a quenching zone 6, an overaging treatment zone 7, and a final cooling zone 8 as shown in (for example, Japanese Patent Application Laid-Open No. 1983-1999).
No. 65937 and Japanese Unexamined Patent Publication No. 61-221334, etc.).

In addition, there are also types that have a preheating zone (not shown) installed on the furnace entry side or a water cooling device (not shown) installed on the furnace exit side. In the figure, reference numerals 9 indicate hearth rolls installed above and below the furnace, and the steel strip S is sequentially wound around these hearth rolls 9 while passing through each zone and being subjected to a predetermined heat treatment. This type of hearth roll 9 is provided with a taper crown, a radial crown, etc. as shown in FIGS. 4a and 4b in order to prevent the steel strip S from meandering. The amount of rounding is determined in consideration of the heat crown in the furnace and within a range that does not cause heat buckling in the copper strip.

Here, the heat treatment in the furnace is performed in a reducing atmosphere gas to prevent oxidation of the copper strip. In addition, common heating methods include roll heating, radiant tube heating, and electric heat heating in the heating/soaking zone, while roll cooling, gas jet cooling, cooling tube cooling, etc. are common in the cooling zone. .

Each zone is connected by a connecting portion 10 so that the steel strip S does not come into contact with the atmosphere. Although FIG. 3 shows a case in which the connecting portion 10 is located at the lower part of the furnace, there is also a case where the connecting part 10 is provided at the upper part of the furnace.

Incidentally, the atmospheric gas temperature in high temperature zones such as the heating zone and the soaking zone is high, while in the cooling zone it is low. Therefore, when these atmospheric gases having different temperatures flow into each other, various problems as described below occur.

That is, when low temperature gas flows into the high temperature side, the heat treatment of the strip is inhibited, and extra fuel is required to prevent the temperature of the atmospheric gas on the high temperature side from decreasing. Furthermore, such cold inflow gas lowers the temperature of the portion of the hearth roll that does not come into contact with the strip, thereby increasing the roll crown, resulting in heat hacking of the strip.

On the other hand, if high-temperature gas flows into the low-temperature side, the cooling process for the strip is inhibited, and it is necessary to increase the cooling power to prevent the temperature of the low-temperature gas from rising. Furthermore, in order to raise the temperature of the portion of the hearth roll that does not come into contact with the strip, the roll crown becomes smaller, and as a result, the strip becomes more likely to meander.

Therefore, in order to prevent these atmospheric gases having different temperatures from flowing into each other, the connecting portion 10 is usually equipped with a seal roll 11 as shown in FIG. 5, or a static pressure pad type seal 12 as shown in FIG. JP-A-63103027) is provided.

(Problems to be Solved by the Invention) However, among the conventional methods described above, in the seal roll method, due to its structure, it is impossible to completely prevent atmospheric gases having different temperatures from flowing into each other. In this regard, with the static pressure pad type seal system, complete isolation is possible if the nozzle is placed as close as possible to the strip S, but if the strip is placed too close, the strip may vibrate, or if it is in poor shape, the nozzle may Not only does contact cause flaws, but the sealing gas itself becomes a disturbance to the heat treatment and has a negative effect on the crown of the hearth roll. Furthermore, there is also the disadvantage that an extra drive device or the like is required separately.

By the way, for example, continuous annealing furnaces for steel strips have recently become faster, thinner, wider, and even softer.
Under such circumstances, it is no longer possible to achieve a satisfactory seal using conventional methods such as the seal roll or static pressure pad type seal as described above.

This invention was developed in view of the above-mentioned current situation.
The purpose of the present invention is to propose a vertical continuous heat treatment furnace that can effectively isolate atmospheric gas in a high temperature zone from that in a cooling zone.

(Means for Solving the Problem) That is, the present invention provides a vertical continuous heat treatment furnace having a high-temperature zone and a low-temperature zone. This is a vertical continuous heat treatment furnace with a communicating passage connected to the bottom of the furnace.

(Function) High-temperature atmospheric gas has a low density, so it tends to rise. On the other hand, the low-temperature atmospheric gas has a high density, so it descends. The present invention effectively blocks mutual inflow of atmospheric gas between the high temperature zone and the cooling zone by utilizing such temperature-dependent properties of gas.

(Example) FIG. 1 schematically shows the main parts of a vertical continuous heat treatment furnace according to the present invention. Two partition walls 13 are provided between a high temperature zone such as a heating zone 1 or a soaking zone 2 and a cooling zone (cooling zone 3 in this example).
13 to form a seal tunnel 14. This seal tunnel 14 is connected to the high temperature zone at the upper part,
On the other hand, it is connected to the cooling zone at the bottom. Further, hearth rolls 9' are provided at the upper and lower parts of the seal tunnel 14, respectively.
, 9' are provided. The metal strip S then enters the sealing tunnel from the upper part of the hot zone and is conveyed to the cooling zone from the lower part.

Here, since the temperature of the atmospheric gas in the high-temperature zone is high and the temperature of the atmospheric gas in the cooling zone is low, the provision of such a seal tunnel 14 prevents the atmospheric gases of the high-temperature zone and the cooling zone from mixing. completely disappears.

Note that the partition wall 13 may have any form such as a furnace wall structure or a steel plate structure.

Now, the tin plate original plate was heat-treated using a continuous annealing furnace of the type shown in FIG. 3(b). The heating temperature was 680°C and the cooling rate was 20°C/s. FIG. 2 shows the temperature change of the final hearth roll in the heating zone 1 at this time. The vertical axis is the temperature of the hearth roll, and the horizontal axis is the elapsed time.

In the figure, the broken line shows the conventional furnace shown in FIG. 3(b), and the solid line shows the case where the seal tunnel disclosed in FIG. 1 according to the present invention is provided in the connecting portion 10 of the same figure.

As is clear from the figure, the roll temperature of the part of the hearth roll in contact with the strip is approximately equal to the heating temperature of 680°C no matter which furnace is used.
When a conventional furnace is used, the roll temperature in the non-contact area is considerably lower than the strip temperature due to the influence of atmospheric gas flowing in from the cooling zone.

In this respect, in the furnace according to the present invention, the temperature of the non-contact part of the rolls is approximately equal to the ambient temperature of 720'C, which indicates that the seal tunnel is functioning effectively.

The atmospheric gas used is H2: 5%, NZ: 95% reducing gas, and the density at 700°C (high temperature zone) is 0.35 kg/m3. At 200°C (cooling zone), the density is 1 kg. /m3.

Note that the present invention is not limited to the above embodiment, and for example, the temperature of the atmospheric gas in the seal tunnel may be actively controlled by providing a heating device or the like.

(Effects of the Invention) According to the present invention, it is possible to effectively block the mutual inflow of atmospheric gas between the high temperature zone and the cooling zone, which not only improves the fuel consumption rate but also prevents meandering of the metal strip and prevents the occurrence of heat buckles. make a major contribution to

Furthermore, the high-temperature gas contains small amounts of H2O, CO, etc., which had the disadvantage of deteriorating the surface quality of the strip if it entered the cooling zone, but this has been prevented and greatly contributed to improving the surface quality. There are also effects such as

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the main parts of the vertical continuous heat treatment furnace according to the present invention, and Fig. 2 is a comparison of the temperature changes of the final hearth roll when the inventive furnace and the conventional furnace are used. Graphs, Figures 3a-d are schematic diagrams of conventional vertical continuous heat treatment furnaces, Figures 4a and b are diagrams showing the roll crowns of hearth rolls, and Figure 5 is a diagram showing the sealing by a seal roll. Figure 6 shows the procedure for sealing using a hydrostatic pad type seal. 1...Heating zone 3...Cooling zone 5.6...Quieting zone 8...Final cooling zone 10...Connection part 12...Static pressure pad type seal 13...Partition wall 2...・Soaking zone 4... Cooling zone 7... Overaging treatment zone 99'... Hearth roll 11... Seal roll 14... Seal tunnel

Claims (1)

[Claims] 1. In a vertical continuous heat treatment furnace equipped with a high-temperature zone and a low-temperature zone, a communication path is provided from the upper part of the high-temperature zone to the lower part of the low-temperature zone as a connection path connecting the high-temperature zone and the low-temperature zone. Vertical continuous heat treatment furnace.