JPH0925510A - Atmospheric heat treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a material heated along a prescribed temp. curve even if the combustion state of radiant tube burners arranged to produce an atmospheric gas in a heating chamber is not changed, to clean the atmosphere in the heating chamber and to prevent the contamination in a furnace caused by vaporized oil content from the material to be heated. SOLUTION: In an atmospheric heat treatment furnace so as to feed exhaust gas of the radiant tube burners 13 into the heating chamber and a cooling chamber as the atmospheric gas by arranging the radiant tube burners 13 in the heating chambers 3a, 3b, a circulating systems 21 for forcedly circulating the atmospheric gas in the heating chamber to the outer part are arranged and gas coolers 22 are arranged in the circulating systems 21 to control the temp. of the heating chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric heat treatment furnace for heat-treating an object to be heated such as a copper tube, a motor core, a transformer core and a metal strip in an atmospheric gas.

[0002]

2. Description of the Related Art A radiant tube burner provided in a heating chamber heats an object to be heated, and exhaust gas of the radiant tube burner is adjusted in its components and temperature to be fed to the heating chamber or the cooling chamber and used as an atmospheric gas. An atmosphere heat treatment furnace which is effectively used is disclosed in Japanese Patent Laid-Open No. 57-
It is already known from the publication such as 79110.

[0003]

By the way, in such an atmospheric heat treatment furnace, since it is necessary to always generate a certain amount or more of the atmospheric gas in order to maintain the quality of the object to be heated, the radiant tube burner is always kept constant. Is kept in a burning state. For this reason, the temperature of the heating chamber may rise more than necessary, and the object to be heated may not be heated in a desired temperature curve.

Further, for example, when a heated object to which processing machine oil or the like adheres is charged into the heating chamber, the atmospheric gas in the heating chamber is contaminated with the evaporated oil and a large amount of soot adheres to the furnace. However, since a large amount of atmospheric gas cannot be fed at a time with the above-described radiant tube burner in the heating chamber, it is possible to wipe off oil vapor etc. in the heating chamber. It was difficult.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and a radiant tube burner is provided in the heating chamber, and the exhaust gas of the radiant tube burner is fed to the heating chamber and the cooling chamber as atmospheric gas. In such an atmosphere heat treatment furnace, a circulation system passage for forcibly circulating the atmosphere gas in the heating chamber to the outside is provided, and a gas cooler is provided in the circulation system passage to control the temperature in the heating chamber. . Further, the present invention is characterized in that, in the atmosphere heat treatment furnace, the atmosphere gas in the heating chamber is always circulated in the minimum necessary amount circulation system path and the oil component in the atmosphere gas is condensed by the gas cooler and recovered.

Even if the combustion of the radiant tube burner is set according to the required amount of ambient gas, the temperature of the heating chamber can be controlled as required by the ambient gas circulating in the circulation system passage. Further, the heating chamber can be cleaned by condensing and collecting the oil component in the atmosphere gas circulating through the circulation system passage by the gas cooler.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings for a copper tube coil bright annealing furnace. FIG. 1 shows a vertical cross section of this atmosphere heat treatment furnace. In the figure, 1 is a charging table, 2 is a front chamber in which the atmosphere gas is replaced by vacuum, 3a ...
3e is a heating chamber, 4a to 4e are cooling chambers, 5 is a rear chamber, and 6 is an extraction table. Partition doors 7, 8 and 9 are provided between the respective chambers. The object to be heated 10 formed by winding a small diameter pipe made of copper in a coil shape is supported by rollers 11 provided in series on the floor surface of each chamber and conveyed in the direction of the arrow as the heat treatment progresses.

The inner surfaces of both side walls of each heating chamber 3a to 3e are shown in FIG.
Radiant tube burner 12 for heating as shown in
Is provided. Reference numeral 121 is a flow control valve for the combustion air of the radiant tube burner 12, and 122 is a control motor provided in the flow control valve 121. Further, 123 is a ratio regulator, and the ratio regulator 123 automatically adjusts the flow rate of fuel to be supplied to the radiant tube burner 12 according to the flow rate of the combustion air. Further, a radiant tube burner 13 for generating an atmospheric gas is provided on the floors of the two heating chambers 3a and 3b near the front chamber. 14 is each of the heating chambers 3a to 3e and the cooling chamber 4
It is the in-furnace gas stirring fan provided on the ceiling part of a to 4e.
In the radiant tube burner 13, the fuel is incompletely combusted in an air-deficient state to generate a non-oxidizing atmospheric gas as a desired component.

A cooler 16 and a refrigerator 17 are provided in the exhaust gas passage 15 of the radiant tube burner 13, and the exhaust gas discharged from the radiant tube burner 13 is cooled by passing through the cooler 16 and the refrigerator 17. It is fed as an atmospheric gas to the heating chamber 3e and the cooling chamber 4a. The atmospheric gas fed to the heating chamber 3e is the heating chamber 3
The atmosphere gas discharged to the outside through d → heating chamber 3e → heating chamber 3b → heating chamber 3a and fed to the cooling chamber 4a is discharged to the outside through the cooling chamber 4b → cooling chamber 4c → cooling chamber 4e.

However, as shown in FIG. 3, the heating chamber 3a and the heating chamber 3b are respectively provided with the circulation system passages 21 for forcedly circulating the atmospheric gas in the heating chambers to the outside by the blower 20, and the respective circulation system passages are provided. 21 is provided with a gas cooler 22. As shown in FIG. 4, the gas cooler 22 is provided with a plurality of heat exchange pipes 23 so as to cross the circulation path 21, and water supply headers 24 and drainage headers 25 are provided at both ends of the heat exchange pipes 23. By circulating the cooling water from the water supply header 24 to the drain header 25, the atmospheric gas flowing through the circulation system passage 21 is cooled. 26 is the heat exchange pipe 2
It is an oil reservoir formed below 3. Further, 27 is a water passage jacket formed on the outer periphery of the duct of the circulation path 21 for cooling the duct.

Reference numeral 28 is an air flow rate adjusting valve provided to adjust the amount of atmospheric gas circulating in the circulation system passage 21, and 29 is a control motor for operating the air flow rate adjusting valve 28.
Reference numeral 30 is a thermocouple for detecting the temperature in the heating chambers 3a and 3b, and 31 is a controller for setting the temperature. The controller 31 compares the temperature in the heating chamber measured by the thermocouple 30 with the set temperature, issues a command to the control motor 29, and adjusts the opening degree of the air volume control valve 28 to control the amount of circulating atmospheric gas and heat. The room temperature is controlled to the set temperature. Further, the controller 31 is provided with a minimum setting function of holding the opening of the air volume control valve 28 so that a certain amount of ambient gas always circulates in the circulation path 21 regardless of the temperature condition. And heating chamber 3
a, the atmospheric gas in the heating chamber 3b always circulates through the minimum necessary amount circulation system passage 21, and the oil content in the atmospheric gas is changed to the heat exchange pipe
The oil is removed from the atmospheric gas by contacting with the air conditioner 3, being cooled, condensed, and collected in the oil sump 26, so that the heating chamber can be cleaned.

The radiant tube burner 12, the thermocouple 30, and the controller 31 are provided in the heating chambers 3a to 3e, respectively, and the temperature of the heating chambers 3a to 3e becomes lower than the set temperature of the controller 31. In this case, the controller 31 issues a command to the control motor 122 to control the combustion state of the radiant tube burner 12 so that the temperature in each of the heating chambers 3a to 3e becomes appropriate.

The circulation path 21 for cleaning the heating chamber
In order to always circulate the minimum required amount of atmospheric gas,
As described above, the controller 31 may be provided with the minimum setting function, but the air volume control valve 28 may be provided with a stopper that prevents the air flow volume control valve from fully closing, or a bypass passage may be provided in parallel with the air volume control valve 28 to provide a minimum required amount. The atmosphere gas may be caused to flow around the bypass passage.

[0014]

As described above, according to the atmospheric heat treatment furnace of the present invention, the atmospheric gas in the heating chamber is forcibly circulated in the circulation system to cool and control the temperature in the heating chamber. The radiant tube burner provided for generating the atmospheric gas in the room can heat the object to be heated with a desired temperature curve without changing the combustion state. Further, the heating chamber can be cleaned by constantly circulating the atmospheric gas in the circulation system to collect the oil, and the inside of the furnace can be prevented from being contaminated by the oil evaporated from the object to be heated.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an atmospheric heat treatment furnace showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the heating chamber of FIG.

FIG. 3 is a vertical cross-sectional view of a heating chamber showing a circulation path according to the present invention.

FIG. 4 is a detailed view of the gas cooler of FIG.

[Explanation of symbols]

 3a to 3e Heating chamber 4a to 4e Cooling chamber 10 Heated object 13 Radiant tube burner 15 Exhaust gas system passage 20 Blower 21 Circulation system passage 22 Gas cooler 28 Air flow control valve 29 Control motor 30 Thermocouple 31 Controller

Claims (2)

[Claims] 1. In an atmosphere heat treatment furnace in which a radiant tube burner is provided in the heating chamber and the exhaust gas of the radiant tube burner is fed to the heating chamber and the cooling chamber as atmospheric gas, the atmospheric gas in the heating chamber is forced to the outside. An atmosphere heat treatment furnace characterized in that a circulation system passage for circulation is provided, and a gas cooler is provided in the circulation system passage to control the temperature in the heating chamber. 2. The atmosphere according to claim 1, wherein the atmospheric gas in the heating chamber is always circulated through the minimum necessary amount circulation system passage so that the oil component in the atmospheric gas is condensed and recovered by the gas cooler. Heat treatment furnace.