JPH07188783A - Atmospheric circulating type heat treatment furnace - Google Patents

Abstract

PURPOSE:To easily drop the temp. in a heating chamber corresponding to change in the setting temp. in the heating chamber without contamination in a short time by circulating atmospheric gas into the heating chamber and a cooling chamber through two gas passages provided with switch valves, respectively. CONSTITUTION:A strip S is carried through the heating chamber 3, cooling chamber also used to slow cooling chamber 4 and cooling chamber 5 in order to execute the heat treatment. In the heating chamber 3, the atmospheric gas is heated through a duct 12 with a circulating fan 11 and supplied into plenum chambers 13, 14 to heat the strip S while holding the float-up. In the cooling chamber 4, an atmospheric gas cooling device 20 provided with a cooler 22 and a circulating fan 21 and plenum chambers 42, 43 are arranged. In this atmosphere circulating type heat treatment furnace 1, the heating chamber 3 and the cooling chamber 4 are connected to the first and the second gas passages 51, 52 and the switch valves 61, 62 are arranged, respectively. Further, a switch valve (showing no figure) is arranged to open and close a cold blast discharging passage of the circulating fan 21 in the cooling chamber 4 on the downstream side of the connected part of the first gas passage 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmosphere circulation type heat treatment furnace for heat treatment of strip by circulating atmosphere gas in the furnace.

[0002]

2. Description of the Related Art As a heat treatment furnace for heat-treating a strip in a non-oxidized state, a muffle furnace for running the strip in a muffle was often used, but as a heat treatment furnace capable of performing heat treatment in a wide treatment temperature range with a short furnace length The muffle-less type atmosphere circulation type heat treatment furnace which forcedly circulates the non-oxidizing atmosphere gas in the furnace has come to be used.

[0003]

However, since this atmosphere circulation type heat treatment furnace is used in a non-oxidizing (including reducing) atmosphere, when changing the set furnace temperature of the heating chamber due to the change of the object to be treated, especially the furnace. At the time of temperature decrease, cooling air could not be fed into the furnace to cool it like in a conventional muffle furnace, so it was unavoidable that strip-shaped dummy material was passed through the furnace to cool the inside of the furnace. There is. However, since the amount of heat taken out of the furnace by this dummy material is small, it takes a long time to cool the inside of the heating chamber, and it is troublesome to carry out the strip running.
Contamination of the furnace atmosphere due to dirt on the surface of the material easily occurs,
There were many problems such as the exhaustion of the dummy material.

The present invention solves the above-mentioned problems of the prior art. When changing the set furnace temperature of the heating chamber, the temperature inside the heating chamber can be lowered easily and in a short time without causing contamination of the atmosphere inside the furnace. The present invention intends to provide an atmosphere circulation type heat treatment furnace which can be performed.

[0005]

The atmosphere circulation type heat treatment furnace according to the first invention of the present application comprises a heating chamber and a cooling chamber arranged on the outlet side of the heating chamber, and the heating chamber and the cooling chamber are provided. In the atmosphere circulation type heat treatment furnace for performing heat treatment on the strip traveling in the furnace by circulating the atmosphere gas respectively, the cold air discharge passage of the atmosphere gas cooling device of the cooling chamber and the heating chamber are connected by the first gas passage. A first on-off valve that connects the furnace gas suction passage of the atmosphere gas cooling device and the heating chamber with a second gas passage, opens and closes the first gas passage, and opens and closes the second gas passage. Two opening / closing valves and a third opening / closing valve that opens / closes the cold air discharge passage on the gas downstream side of the first gas passage connecting portion are provided.

The atmosphere circulation type heat treatment furnace of the second invention of the present application comprises a heating chamber and a cooling chamber disposed on the outlet side of the heating chamber, and circulates atmospheric gas in the heating chamber and the cooling chamber, respectively. In the atmosphere circulation type heat treatment furnace for heat-treating the strip traveling in the furnace, the cooling gas flow path of the atmosphere gas cooling device of the cooling chamber and the vicinity of the gas circulation fan suction port of the heating chamber are connected to the first gas. A second on-off valve for connecting and disconnecting the in-furnace gas suction passage of the atmosphere gas cooling device and the heating chamber by a second gas passage to connect and disconnect the first gas passage and the second gas passage. And a second opening / closing valve for opening / closing.

[0007]

In the atmosphere circulation type heat treatment furnace of the first invention, the first opening / closing valve and the second opening / closing valve are opened and the third opening / closing valve is opened in order to lower the temperature of the heating chamber when the set furnace temperature of the heating chamber is changed. Close and operate the ambient gas cooler in the cooling chamber.
The ambient gas cooled by the ambient gas cooling device flows in the first gas passage and is supplied into the heating chamber, and the high-temperature ambient gas in the heating chamber flows in the second gas passage, and inside the furnace of the ambient gas cooling device. The temperature in the heating chamber is reduced for a short time by the atmosphere gas cooling device that is cooled through the gas suction passage and is supplied into the heating chamber, and the atmosphere gas is circulated between the cooling device in the cooling chamber and the heating chamber that is the object of temperature reduction. To descend.

During the heat treatment operation, the first opening / closing valve and the second opening / closing valve
When the on-off valve is closed, the gas flow between the heating chamber and the cooling chamber is shut off, and the atmosphere gas cooled by opening the third on-off valve is circulated in the cooling chamber, so that the normal object to be processed can be cooled. .

In the atmosphere circulation type heat treatment furnace of the second invention, in order to lower the temperature of the heating chamber when the set furnace temperature of the heating chamber is changed, the first opening / closing valve and the second opening / closing valve are opened,
The cooler of the atmosphere gas cooling device in the cooling chamber is set to the cooling operation state, and the gas circulation fan in the heating chamber is operated. Due to the suction action of the gas circulation fan, the ambient gas cooled by passing through the cooler 22 from the in-furnace gas suction passage side of the ambient gas cooling device enters the heating chamber from the cooling gas passage through the first gas passage. The gas is sucked, sucked by the circulation fan and pressurized and supplied into the heating chamber, and the high-temperature atmospheric gas in the heating chamber flows in the second gas passage and is passed by the cooler through the in-furnace gas suction passage of the atmospheric gas cooling device. The temperature of the heating chamber is cooled and sucked from the cooling gas flow path into the heating chamber, and the temperature of the heating chamber is changed by circulation of the atmospheric gas between the front and rear portions of the cooler of the atmospheric gas cooling device of the cooling chamber and the heating chamber to be cooled. It descends in a short time.

During the heat treatment operation, the first opening / closing valve and the second opening / closing valve
When the on-off valve is closed, the gas flow between the heating chamber and the cooling chamber is cut off, and the cooled atmosphere gas is circulated in the cooling chamber, so that the normal object to be processed can be cooled.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention will be described below with reference to FIGS. In FIG. 1, 1 is a floating furnace type atmosphere circulation type heat treatment furnace, 2 is a front chamber, 3 is a heating chamber following this front chamber, 4 is a slow cooling chamber connected to the outlet side of this heating chamber A cooling chamber 5 also serving as a cooling chamber, 5 is a cooling chamber dedicated to cooling that follows this cooling chamber, and 6 is a rear chamber on the outlet side of this cooling chamber. 7
Is a roll type seal device installed at the front chamber inlet, and 8 is a roll type seal device installed at the rear chamber outlet.

In the heating chamber 3, there are two circulation fans 11, 1
1, the gas discharged by these fans flows down in ducts 12 (only one side is shown in the figure) provided along the left and right side walls with respect to the furnace length direction and is heated by the heater. , A strip S, which is a material to be processed, is floated and held by being jetted upward from the gas outlet of the lower plenum chamber 13, and is also jetted downward from the gas outlet of the upper plenum chamber 14. S is suppressed and stabilized and heated.

The cooling chamber 4 has a partition wall 4 at the ceiling thereof.
At the upper part of a, an atmosphere gas cooling device 20 is provided, which has a circulation fan 21 and a cooler 22 connected to a cooling water supply source (not shown) as main equipment. Reference numeral 23 denotes an in-furnace gas suction passage that opens downward and communicates with the inside of the cooling chamber 4, and the cooler 22 is provided between this in-reactor gas suction passage 23 and the suction port 21a of the circulation fan 21. Then cooler 2 during slow cooling
2 is transversely driven as shown by an arrow R in FIG.
A part thereof is housed in a recess 25 surrounded by 4, and a gas passage port 27 (fully opened) which communicates the in-furnace gas suction passage 23 and the cooling gas passage 26 on the cooler outlet side where the suction inlet 21a is opened. Width =
By changing the protrusion amount V of the curler 22 into W),
It is designed to adjust the amount of gas cooling.

As shown in FIGS. 3 and 4, the cooler 22 has wheels 29 axially supported by a hanger 28 projecting from the upper portion thereof and engaged with rails 30 and 30 extending in the furnace width direction. The chain 33 is put in a suspended state by combining them, and the chain 33 wound around the sprockets 31 and 32 axially supported by the furnace body is attached to the hanger.
28 to connect one sprocket 31 to the motor 34.
The chain 30 is driven by a chain by means of
However, other driving and supporting structures such as using an air cylinder may be adopted.

The duct 41 connected to the discharge port 21b of the circulation fan 21 is branched and connected to the upper plenum chamber 42 and the lower plenum chamber 43, and the discharge port 21b.
The cooled discharge gas from is jetted upward from the gas outlet of the lower plenum chamber 43 to float and hold the strip S in the same manner as in the heating chamber 3, and cools the strip S as well. The strip S is pressed downward from the gas outlet of the upper plenum chamber 42 to press and cool the strip S.

In FIG. 1, reference numeral 51 denotes a first gas passage formed of a duct, one end portion 51a of which is connected to an air supply port 55 formed in the furnace body near the rear end portion of the heating chamber 3 and the other end thereof. The portion 51b is the cold air discharge passage 4 of the circulation fan 21 of the cooling chamber 4.
It is connected to a duct 41 (see FIG. 2) that constitutes 1a. Reference numeral 52 is a second gas passage formed of a duct, one end portion 52a of which is connected to an exhaust port 56 formed in a furnace body near the front end portion of the heating chamber 3, and the other end portion 52b thereof is a gas inside the cooling chamber 4. It is connected to the suction path 23.

Reference numeral 61 denotes a first gas passage provided in the first gas passage 51.
An on-off valve, 62 is a second on-off valve provided in the second gas passage 52,
Reference numeral 63 denotes a third on-off valve (see FIG. 2) provided on the gas downstream side (plenum chamber side) of the connection portion of the first gas passage 51 in the cold air discharge passage 41a, and each is a butterfly valve type. And is opened and closed by an air cylinder (not shown).

Further, in FIG. 1, the cooling chamber 5 is also provided with an atmosphere gas cooling device 70 having a cooler 71 and a circulation fan 72 as main components, and the cooling gas discharged from the circulation fan 72 is plenum chambers 73 and 74. Are supplied to the strip S to keep the strip S floating and to cool it.
The cooler 71 is fixed to cool the entire circulation flow rate of the atmospheric gas, and has the same atmospheric gas circulation structure in the furnace as the cooling chamber 4.

In the atmosphere circulation type heat treatment furnace 1 having the above-mentioned structure, the first on-off valve 61 and the second
With the open / close valve 62 closed and the third open / close valve 63 open, the heating atmosphere gas is circulated in the heating chamber 3, and the cooler 22 is desired in the cooling chamber 4 according to the processing conditions of the target strip S. By circulating the cooling atmosphere gas in the protruding state and circulating the cooling atmosphere gas in the cooling chamber 5, the traveling strip S is heat-treated.

When the set furnace temperature of the heating chamber 3 is to be lowered in accordance with the change of the material type and size of the strip S, the strip is stopped and the sealing devices 7 and 8 are in the sealing state. Open the first on-off valve 61 and the second on-off valve 62,
The ambient gas cooling device 20 is operated by closing the third opening / closing valve 63 and setting the cooler 22 in the cooling chamber 4 to the fully projected state shown by the solid line. The low-temperature atmosphere gas cooled by the cooler 22 and discharged by the circulation fan 21 is fed into the heating chamber 3 through the first gas passage 51 to cool the inside of the heating chamber 3. The high-temperature gas in the heating chamber 3 is cooled from the second gas passage 52 through the in-furnace gas suction passage 23 of the cooling chamber 4 by passing through the cooler 22 and is circulated and supplied again to the heating chamber 3 by the circulation fan 21. With this circulating gas flow, the temperature inside the heating chamber 3 can be lowered in a short time.

It is preferable to replenish and supply a new atmospheric gas from the atmospheric gas supply source to the inside of the furnace, for example, so that the inside of the furnace becomes negative pressure due to the cooling and the outside air is not sucked. When the temperature inside the heating chamber 3 drops to a predetermined temperature, each on-off valve can be returned to its original state, so that the next heat treatment can be started.

Next, FIG. 5 shows an embodiment of the second invention, and one end portion 51a of the first gas passage 51 composed of a duct.
Is the inlet 1 of the circulation fan 11A on the furnace inlet side of the heating chamber 3.
1a is connected to an intake port 57 formed in the furnace body, and the other end 51b is connected to a cooling gas passage 26 on the outlet side of the cooler 22 of the ambient gas cooling device 20 of the cooling chamber 4. The third opening / closing valve 63 shown in FIG. 2 is omitted, and has the same structure as that of the above embodiment.

In the atmosphere circulation type heat treatment furnace 81 of this embodiment, the first opening / closing valve 61 and the second opening / closing valve 62 are closed during the normal heat treatment, and the traveling strip S is heat treated in the same manner as in the above-mentioned embodiment. .

When lowering the set furnace temperature of the heating chamber 3,
The first on-off valve 61 and the second on-off valve 62 are in the strip stopped state and the seal devices 7 and 8 are in the sealed state.
Is opened, the cooler 22 in the cooling chamber 4 is fully projected, and water is passed through the cooler 22 to bring it into a cooling operation state, and the circulation fan 11A in the heating chamber 3 is operated. Circulation fan 11A
By the suction action of the cooler 2 from the gas suction passage 23 in the furnace.
The low-temperature atmospheric gas cooled by passing through 2 is sucked into the heating chamber 3 from the cooling gas passage 26 through the first gas passage 51, sucked from the suction port 11a of the circulation fan 11A, and discharged from the circulation fan. It is supplied into the heating chamber 3 from the plenum chambers 13 and 14 via the duct 12 connected to the outlet to cool the inside of the heating chamber 3. The high-temperature gas in the heating chamber 3 is cooled from the second gas passage 52 through the in-furnace gas suction passage 23 of the cooling chamber 4 by passing through the cooler 22 and is circulated and sucked into the heating chamber 3 again by the circulation fan 11A. With this circulating gas flow, the temperature inside the heating chamber 3 can be lowered in a short time.

In the above embodiment, one end portion 51a of the first gas passage 51 has one circulation fan 1 in the heating chamber 3.
Although it is connected to the vicinity of the suction port 11a of 1A, it is connected to the vicinity of the respective suction ports of the two circulation fans 11A, 11 by branching the first gas passage 51, for example. The gas suction from the cooling gas passage 26 and the pressurized supply into the heating chamber 3 may be performed by the operation of.

As described above, the opening / closing operation of each on-off valve and the atmosphere gas cooling device 20 in the cooling chamber 4 (in the case of the first invention) or the circulation fan 11A in the heating chamber 3 (in the case of the second invention).
The temperature drop in the heating chamber 3 can be performed easily and in a short time, and only the atmosphere gas is circulated for cooling. Therefore, the atmosphere in the furnace as in the case of passing the dummy material is used. Also, it does not cause the pollution or the consumption of the dummy material.

The present invention is not limited to the above embodiments, and the third on-off valve 63 may also serve as a damper for adjusting the amount of gas supplied to the plenum chambers 42, 43, for example. In addition, the first gas passage 51 and the second gas passage 52 are not provided in the cooling chamber 4 in the immediate vicinity but in the cooling chambers 5 separated from each other.
You may connect to.

In the above embodiment, the cooling chamber 4 also serves as a slow cooling chamber, but the present invention has an atmosphere circulation system having at least one cooling chamber for cooling equipped with a fixed cooler. It is also applicable to a heat treatment furnace. Further, the present invention can be applied to an atmosphere circulation type heat treatment furnace using a hearth roll as a strip material holding means.

[0029]

As described above, according to the present invention,
The atmosphere gas in the furnace cooled by the atmosphere gas cooling device in the cooling chamber is fed into the heating chamber through the first gas passage (in the case of the first invention) or cooled by the cooler of the atmosphere gas cooling device in the cooling chamber. The furnace atmosphere gas is sucked into the heating chamber through the first gas passage (in the case of the second invention), and the furnace atmosphere gas in the heating chamber is returned to the atmosphere gas cooling device through the second gas passage. As a result, the temperature of the heating chamber can be lowered when changing the set furnace temperature of the heating chamber easily and in a short time without causing contamination of the atmosphere in the furnace, contributing to the improvement of the operating rate of the atmosphere circulation type heat treatment furnace. To do.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an atmosphere circulation type heat treatment furnace showing an embodiment of the first invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

4 is a cross-sectional view taken along the line CC of FIG.

FIG. 5 is a longitudinal sectional view of an essential part of an atmosphere circulating heat treatment furnace showing an embodiment of the second invention.

[Explanation of symbols]

1 ... Atmosphere circulating heat treatment furnace, 3 ... Heating chamber, 4 ... Cooling chamber,
11A ... Circulation fan, 20 ... Atmosphere gas cooling device, 21
... Circulation fan, 22 ... Cooler, 23 ... Furnace gas suction passage,
26 ... Cooling gas passage, 41 ... Duct, 41a ... Cold air discharge passage, 51 ... First gas passage, 51a ... One end, 51b ... Other end, 52 ... Second gas passage, 52a ... One end, 52b ...
The other end, 55 ... air supply port, 56 ... exhaust port, 57 ... intake port,
61 ... 1st on-off valve, 62 ... 2nd on-off valve, 63 ... 3rd on-off valve, S ... Strip, 81 ... Atmosphere circulation type heat treatment furnace.

Claims (2)

[Claims] 1. A heating chamber and a cooling chamber provided on the outlet side of the heating chamber are provided, and atmospheric gas is circulated in each of the heating chamber and the cooling chamber to heat-treat a strip traveling in the furnace. In the atmosphere circulation type heat treatment furnace, the cold air discharge passage of the atmosphere gas cooling device of the cooling chamber and the heating chamber are connected by a first gas passage, and the furnace gas suction passage of the atmosphere gas cooling device and the heating chamber are connected. A first opening / closing valve that connects with a second gas passage and opens / closes the first gas passage, a second opening / closing valve that opens / closes the second gas passage, and the cold air discharge passage from the first gas passage connecting portion An atmosphere circulation type heat treatment furnace comprising a third opening / closing valve that opens and closes on the downstream side. 2. A heating chamber and a cooling chamber disposed on the outlet side of the heating chamber are provided, and atmospheric gas is circulated in the heating chamber and the cooling chamber, respectively, to heat-treat a strip traveling in the furnace. In the atmosphere circulation type heat treatment furnace, the cooling gas flow path of the atmosphere gas cooling device of the cooling chamber and the vicinity of the gas circulation fan suction port of the heating chamber are first
A first opening / closing valve for connecting the gas passage to connect the in-furnace gas suction passage of the ambient gas cooling device and the heating chamber with a second gas passage to open / close the first gas passage, and the second gas passage. And a second opening / closing valve for opening and closing.