JPS61177316A - Continuous heat treating furnace for metallic material - Google Patents

Abstract

PURPOSE:To utilize directly the heat quantity of a waste gas and to improve thermal efficiency by providing a preheating chamber segmented by open/shut doors, a heat treating chamber, etc., and making possible the supply of the high-temp. waste gas in the heat treating chamber to the preheating chamber. CONSTITUTION:This continuous heat treating furnace T for a metallic material consists of the preheating chamber 2 segmented by the open/shut doors 1A-1G, a purging chamber 4, the heat treating chamber 5, an extraction preparing chamber 6, radiant tubes 7 disposed in the heating chamber 5a of the chamber 5 and a waste gas supply duct 14a. The duct 14a is used to introduce the waste gas from the radiant tubes 7 into the chamber 2. The material to be treated is heat-treated with good thermal efficiency in the protective atmosphere by the above-mentioned furnace T.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a continuous heat treatment furnace for metal materials, specifically, a roller hearth type, a truck type, and a tray presser set that directly uses high-temperature exhaust gas from a radiant tube as a preheating source. This relates to continuous heat treatment furnaces such as the following.

(Prior art) Conventionally, when continuously heat treating metal materials such as steel plates, nonferrous metal materials, metal strip coils, wire coils, and forged parts, heating and cooling must be performed in a specified protective atmosphere, and radiant tubes are used in the heating area. Alternatively, an indirect heating means such as an electric heater can be installed for heat treatment, and purge chambers (charging preparation chamber, extraction preparation chamber) can be installed on both sides of the furnace to prevent outside air from entering the furnace. There is.

In the continuous heat treatment furnace, when a preheating zone is installed for the purpose of improving thermal efficiency, Japanese Patent Application Laid-Open No. 51-6061
As proposed in Publication No. 6 or Japanese Utility Model Application Publication No. 51-68805, a preheating zone with a heat exchange pipe is installed after the charging preparation chamber, and the exhaust gas from the radiant tube or the cooling gas is stored in the heat exchange pipe. A system in which heated exhaust gas is supplied to the belt and the heat of the exhaust gas is used indirectly, and JP-A-57-13
As proposed in Japanese Patent No. 7418, there is a method in which the atmosphere is circulated between the preheating zone and the cooling zone, and the heat dissipated during cooling is used for preheating.

(Problems to be Solved by the Invention) However, in the former method, since the exhaust gas is supplied to the heat exchange pipe, preheating efficiency is poor and equipment costs increase. On the other hand, the latter method is more effective than the former in that it uses exhaust gas directly, but if the material to be treated has impurities such as oil attached, the material will be exposed to an atmosphere containing impurities in the cooling zone. During cooling, not only will the material to be treated be contaminated, but if it contains moisture, the dew point will rise in the cooling zone, causing oxidation of the material to be treated.

Furthermore, since the pre-charging zone is located after the charging preparation chamber, the charging preparation chamber must be purged of outside air (air) when charging the material to be processed, and a large amount of purging gas (N
, etc.).

The present invention has been made to eliminate the above-mentioned conventional drawbacks.

(Means for Solving the Problems) The present invention provides a continuous heat treatment furnace for heat treating metal materials in a protective atmosphere, in which the furnace is divided into a preheating chamber, a purge chamber, a heat treatment chamber, and an extraction preparation chamber by an opening/closing door. A radiant tube is disposed in a heating area of the heat treatment chamber, and an exhaust gas supply duct is provided for introducing exhaust gas from the radiant tube into the preheating chamber.

(Example) The continuous heat treatment furnace T according to the present invention has an opening/closing door 1A-IE
Preheating chamber 2. Purge chamber 4. It is divided into a heat treatment chamber 5 and an extraction preparation chamber (extraction bestible) 6.

The heat treatment chamber 5 is further divided into a heating (soaking) chamber 5a, an annealing chamber 5b, and a cooling chamber 5C by opening/closing doors IF and IG.
1, a radiant tube 7 is provided in the heating chamber 5a, an air cooling tube 8 is provided in the slow cooling chamber 5b, and air from the blower 9 is supplied to the air cooling tube 8, and then transferred to the heat exchanger 15. is supplied as combustion air to the radiant tube 7 via the radiant tube 7, while high temperature exhaust gas from the radiant tube 7 is directly supplied into the preheating chamber 2 from the exhaust gas supply duct 14a via the heat exchanger I5. It looks like this.

In addition, convection fans 3 are installed on the ceilings of the preheating chamber 2 and the cooling chamber 5c.
．． IO is provided.

Next, the operation of the heat treatment furnace constructed as described above will be described.

Now, while driving the blower 9, fuel is supplied to the radiant tube 7 for combustion to raise the temperature in the heating chamber 5a to a predetermined temperature, and the exhaust gas is supplied to the preheating chamber 2 to make the inside of the furnace ready for operation. Suppose there is.

At this time, the opening/closing door (charging door) IA is opened (the opening/closing door IB is closed), and the processing material W on the charging table (not shown) is loaded at a predetermined position (W, ) in the preheating chamber 2. After entering, close the opening/closing door IA. The processing material (W+
) is transported to the extraction side, and during this time the treated material W is uniformly preheated by a convection fan while receiving convective heat conduction. In addition, when charging the heat-treated material into the preheating chamber 2, when the previously treated material has moved to the predetermined position (W,), open the opening/closing door IA and load it into the preheating chamber 2 at the predetermined position (W+). It is something to enter,
Thereafter, similar operations are repeated to sequentially load processing materials.

When the preheating is completed, the opening/closing door IB is opened (the opening/closing door IC is closed) and the processing material (W) located at the extraction end in the preheating chamber 2 is
3) is transferred to the purge chamber 4 and the opening/closing door IB is closed, and then the inside of the chamber 4 is purged with a purge gas such as N or gas. When the purge is completed, the opening/closing door IC is opened (the opening/closing door IB is in the closed state), and the processing material W is transported from the purge chamber 4 with a mixed gas of N2 gas and N2 gas, N2 gas and CO, gas and H , to a predetermined position (W, ) in the heating chamber 5a to which a reducing protective atmosphere gas such as a mixed gas with gas is supplied, and the opening/closing door IC is closed. Thereafter, similarly, the processing materials in the preheating chamber 2 are sequentially transferred to the heating chamber 5a.

On the other hand, the treated material W transferred to the heating chamber 5a is heated and soaked to a predetermined temperature in a predetermined protective atmosphere while being transported inside the heating chamber 5a to the extraction side.

When heating and soaking are completed, open the opening/closing door IF (opening/closing door IG).
(closed state), the processing material located at the extraction end in the heating chamber 5a is transferred to the slow cooling chamber 5b, where the same protective atmosphere gas as in the heating chamber 5a is supplied, and the opening/closing door IF is closed. The processing material W in the slow cooling chamber 5b is slowly cooled by the air cooling tube 8 that supplies air, while the air in the slow cooling tube 8 is preheated and passes through the heat exchanger 15 to the radiant tube in the heating chamber 5a. The combustion air is supplied to the burner section No. 7 as high-temperature combustion air.

When the slow cooling is completed, the opening/closing door IG is opened (the opening/closing door IF is in the closed state), and the processing material W is transferred from the slow cooling chamber 5b to N.

After moving to the cooling chamber 5c where a protective atmosphere gas such as gas is supplied, the opening/closing door IG is closed. And the treated material W
is slowly cooled to a predetermined temperature by a fan IO while being transported to the extraction side, and then extracted from the extraction preparation chamber (extraction bestiple) 6 to the outside of the furnace.

Note that if the pressure in the slow cooling chamber 5b is set to be somewhat higher than that in the heating chamber 5a and the cooling chamber 5c, the heating chamber 5a and the cooling chamber 5
It is possible to reliably prevent the atmospheres of c from mixing.

During the operation, if the temperature in the preheating chamber 2 becomes higher than the predetermined temperature, this is detected by the temperature detector I2, and the control valve 13 is opened to remove the air from the blower 9 to the branch duct 14b. Exhaust gas supply duct 14
a and adjust the exhaust gas temperature to a predetermined temperature.

In the above embodiments, a roller hearth type furnace equipped with hearth rollers as a conveying means was explained, but it can also be applied to other continuous furnaces, such as a bogie type furnace and a tray-type furnace. Not only a linear arrangement but also a U-shaped arrangement may be adopted as appropriate depending on the conveying means.

(Effects of the Invention) As described above, according to the continuous heat treatment furnace of the present invention, the high temperature exhaust gas from the radiant tube arranged in the heat treatment chamber is supplied to the preheating chamber, and the calorific value of the exhaust gas is directly utilized. Therefore, the processing material can be efficiently preheated. In this case, as shown in the embodiment, if a convection fan is provided in the preheating chamber, the processing material can be preheated more efficiently and uniformly by the convection heat conduction.

In addition, since the purge chamber is interposed between the preheating chamber and the heating chamber, the combustion exhaust gas in the preheating chamber does not enter the heating chamber, which not only reliably prevents atmospheric pollution in the heat treatment chamber, but also allows air purge ( Since combustion exhaust gas (containing 1 to 2% Ox) is present, unlike the oxidation gas (containing 21% Os), purging can be performed in a short time with a small amount of purge gas.

In addition, as shown in the example, if a slow cooling chamber is provided between the heating chamber and the cooling chamber, it is possible to prevent the atmospheres of the heating chamber and the cooling chamber from mixing, and not only can good processing be performed. The heating chamber and the cooling chamber can be treated as different protective atmospheres, and an air cooling tube can be provided in the slow cooling chamber to effectively perform slow cooling.

Furthermore, a heat exchanger 15 is provided in the radiant tube,
The combustion air to the radiant tube is heat exchanged with high-temperature exhaust gas, and the air from the proa is supplied into the air cooling tube of the slow cooling chamber, and the heat dissipated from the treated material W during slow cooling is used for combustion of the radiant tube. It can be used to preheat air, and it is also possible to achieve significant energy savings.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a continuous heat treatment furnace according to the present invention, Fig. 2 is an explanatory diagram of a continuous heat treatment furnace according to the present invention;
The figure is a diagram showing the state of the piping in FIG. 1. IA to IG... Opening/closing door, 2... Preheating chamber, 3... Convection fan, 4... Purge chamber, 5... Heat treatment chamber, 5a
... slow cooling room, 5C... cooling room, 6... extraction preparation room, 7... radiant tube, death = air cooling tube, 9
...Blower, IO...Convection fan.

Claims (4)

[Claims] (1) In a continuous heat treatment furnace that heat-treats the material to be treated in a protective atmosphere, the furnace is divided into a preheating chamber, a purge chamber, a heat treatment chamber, and an extraction preparation chamber by an opening/closing door, and the heating area of the heat treatment chamber is Along with installing a radiant tube,
A continuous heat treatment furnace for metal materials, comprising an exhaust gas supply duct for introducing exhaust gas from the radiant tube into the preheating chamber. (2) The continuous heat treatment furnace for metal materials according to claim 1, wherein the preheating chamber is equipped with a convection fan. (3) Claim 1 or 2, wherein the heat treatment chamber is divided by an opening/closing door into a heating chamber equipped with a radiant tube, a slow cooling chamber, and a cooling chamber. Continuous heat treatment furnace for metal materials described in . (4) The slow cooling chamber has one end connected to a combustion air supply blower,
The continuous heat treatment furnace for metal materials according to claim 3, further comprising an air-cooled tube whose other end is connected to a radiant tube combustion air supply section of the heating chamber.