JPH093533A - Cooling device in heating chamber for heat treatment - Google Patents

Abstract

PURPOSE: To shorten slow cooling speed of a heat radiating material in a heating chamber and to efficiently execute the heat treatment by introducing the low temp. atmosphere of a quenching chamber into the heating chamber with the back pressure of a stirring fan arranged in the heating chamber of an atmospheric heat treatment furnace. CONSTITUTION: A metallic product 5 to execute carburizing treatment is charged into the heating chamber 1 in a gas carburizing furnace and the carburizing treatment is executed with carburizing, atmospheric gas of CO base gas, etc., while heating to about 930 deg.C with radiant tube burners 3. Successively, after slowly cooling to 850 deg.C in the heating furnace 1, the carburized product 5 is shifted into the quenching chamber 7 continued from the heating chamber 1, and dipped into a quenching oil vessel 10 at the lower part by acting a cylinder 12. In this case, the heating chamber 1 and the quenching chamber 7 are connected with a duct 13 and the slow cooling time of the metallic product 5 already completing the carburizing treatment in the heating chamber 1 is shortened by utilizing the back pressure generated with the rotation of the stirring machine 4 in the heating chamber 1 to introduce the low temp. atmosphere in the quenching chamber 7 into the heating chamber 1, and then, the operating ratio of the gas carburizing furnace is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating chamber cooling apparatus for heat treatment which can accelerate a cooling rate of a material in a heating chamber in an atmospheric heat treatment furnace such as a gas carburizing furnace to shorten a required processing time. .

[0002]

2. Description of the Related Art For example, in a gas carburizing furnace, a heated object such as a steel material is heated to a high temperature of about 930.degree. C. as shown in FIG. 4 based on a carburizing atmosphere gas such as a CO-based gas or a hydrocarbon-based gas. After soaking the carbon in the object to be heated and diffusing it by soaking, the object to be heated is left to stand in the heating chamber as it is to be naturally cooled and gradually cooled to about 850 ° C., and then the object to be heated Is moved to the subsequent quenching chamber, immersed in oil and rapidly cooled to harden the surface of the material.

[0003]

By the way, in the above-mentioned heat treatment, since the object to be heated in the heating chamber is naturally cooled, it takes about 2 hours for cooling, which causes a problem of low processing capacity. It was Further, if the heating / soaking temperature is further raised to about 1000 ° C. in order to improve the carburizing property, the time required for the above-mentioned gradual cooling becomes longer and takes about 4 hours, resulting in a further problem of inefficiency.

However, if the forced cooling means such as a cooler is provided in the heating chamber, not only the facility cost is increased but also the object to be heated may be unevenly cooled to cause distortion. Was not desirable in the heating chamber.

[0005]

The heating chamber cooling device for heat treatment according to the present invention is intended to solve the above-mentioned problems, and the back surface of a stirring fan provided in the heating chamber communicates with a chamber lower in temperature than the heating chamber. It is characterized in that a vent hole is opened and an atmospheric gas is introduced into the heating chamber by the back pressure of the stirring fan to gradually cool the object to be heated in the heating chamber. Further, the present invention is characterized in that, in the heating chamber cooling device for heat treatment, a damper is provided in a duct connecting the low temperature chamber and the vent hole. The low temperature chamber is specifically a quenching chamber or a cooling chamber subsequent to the heating chamber.

[0006]

Since the back pressure of the agitating fan provided in the heating chamber is used to introduce the atmospheric gas from the low temperature chamber and mix it with the atmospheric gas in the heating chamber to hit the object to be heated in the heating chamber,
The object to be heated can be uniformly gradually cooled, and the time required for the heat treatment can be shortened.

[0007]

EXAMPLES Next, examples of the present invention will be described with reference to FIGS. 1 and 2 for a gas carburizing furnace. In the figure, 1 is a heating chamber,
Reference numeral 2 is an opening / closing door of the heating chamber 1, 3 is a radiant tube burner as a heat source provided on the inner surface of the side wall of the heating chamber 1, 4 is a stirring door provided at the ceiling of the heating chamber 1, and 5 is the heating chamber. 1
The object to be heated is supported by the hearth roller 6 of. Reference numeral 7 is a quenching chamber which is connected to the heating chamber 1 on the rear side, 8 is an opening / closing door for partitioning the heating chamber 1 and the quenching chamber 7, and 9 is an extraction door of the hearth roller 6. A quenching oil tank 10 is formed under the floor of the quenching chamber 7. The hearth roller 11 in the quenching chamber 7 moves up and down by the operation of the cylinder 12 while supporting the object 5 to be heated.
Can be immersed in the quenching oil tank 10.

However, 13 is a duct that connects the quenching chamber 7 and the heating chamber 1, 14 is a damper provided in the duct 13, and the duct 13 is a ventilation port provided on the rear surface of the stirring fan 4 of the heating chamber 1. It communicates with 15.

In the gas carburizing furnace thus constructed, the radiant tube burner 3 is used as a heat source and the stirring fan 4 is rotated to heat the object 5 to be heated in the heating chamber 1 to about 1000 ° C. under the carburizing atmosphere gas. As shown in FIG. 3, after maintaining the temperature for about 20 minutes for soaking, the damper 14 is opened to allow the low-temperature atmosphere gas in the quenching chamber 7 to be heated in the heating chamber 1 by the back pressure of the stirring fan 4. And the object 5 to be heated is gradually cooled. In this way, by mixing the atmosphere gas in the quenching chamber 7 with the atmosphere gas in the heating chamber 1, stirring the mixture, and applying the mixture to the object to be heated 5, the time required for gradual cooling can be significantly shortened. For example, as shown in FIG. 3, it takes only 2 hours to cool to a quenching temperature of 1000 ° C. to 850 ° C. After that, the opening / closing door 8 is opened to move the object 5 to be heated to the quenching chamber 7, and is immersed in the quenching oil tank 10 for 1 minute to be rapidly cooled for desired carburizing and quenching.

On the other hand, FIG. 5 shows a roller hearth type continuous atmosphere heat treatment furnace for copper tube coil annealing according to another embodiment of the present invention. In the figure, 20 is a front table, 21 is a front chamber, 22 is an inlet throat, 23 is a heating chamber, 24 is a cooling chamber, 25 is a rear chamber, and 26 is a rear table. Heating room 2
As shown in FIG. 6, the ribbon heater 27, which serves as a heat source, is shown in FIG.
And a stirring fan 28 is provided on the ceiling. Further, the cooling chamber 24 is provided with a blower 29 and a cooler 30 for forcibly circulating the atmosphere gas in the furnace. However, in this heat treatment furnace, the stirring fan 2 near the cooling chamber 24 of the heating chamber 23
A ventilation port 31 is provided on the back surface of the heating chamber 8 and the atmospheric gas in the cooling chamber 24 is passed through the duct 32 when gradually cooling the object 34 located in the heating chamber 23 by the back pressure of the stirring fan 28.
It can be introduced in 3. 33 is the duct 32
It is a damper installed in. FIG. 7 shows a heat curve of the continuous atmosphere heat treatment furnace. In FIG. 7, the solid line shows the temperature change of the atmosphere gas, and the broken line shows the temperature change of the object 31 to be heated. The damper 33 is opened so that the atmosphere gas in the cooling chamber 24 is heated by the heating chamber 23.
In the case of introducing into the heating chamber 23, the temperature of the atmosphere gas in the portion of the heating chamber 23 near the cooling chamber 24 can be lowered so that a part of the heating chamber can substantially function as a slow cooling zone. Therefore, the present invention is also effective as a means for setting a desired heat curve as in this embodiment. In these examples, the atmospheric gas was introduced from the cooling chamber or the quenching chamber, but the atmospheric gas was introduced from a chamber having a lower temperature than other heating chambers (for example, front chamber, preheating chamber, rear chamber, etc.). May be.

[0011]

As described above, according to the heating chamber cooling apparatus for heat treatment of the present invention, the back pressure of the stirring fan provided in the heating chamber is used to introduce the atmospheric gas from the low temperature chamber so as to cover the heating chamber. Since the heat product can be uniformly and gradually cooled in a short time, there is a beneficial effect of improving workability of heat treatment and quality.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a gas carburizing furnace showing an embodiment of a heat treatment heating chamber cooling device according to the present invention.

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

FIG. 3 is a heat cycle diagram of carburization.

FIG. 4 is a heat cycle diagram of carburization.

FIG. 5 is a vertical cross-sectional view of a continuous atmosphere heat treatment furnace showing another embodiment of the heat treatment heating chamber cooling device according to the present invention.

6 is a cross-sectional view of the heating chamber of FIG.

7 is a heat curve diagram of the continuous atmosphere heat treatment furnace of FIG.

[Explanation of symbols]

 1 Heating Chamber 3 Radiant Tube Burner 4 Stirring Fan 5 Heated Object 7 Quenching Chamber 10 Quenching Oil Tank 13 Duct 14 Damper 15 Vent

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F27B 9/30 F27B 9/30 F27D 9/00 F27D 9/00

Claims (4)

[Claims] 1. A vent hole communicating with a chamber having a temperature lower than that of the heating chamber is provided on the back surface of the stirring fan provided in the heating chamber, and an atmospheric gas is introduced into the heating chamber by the back pressure of the stirring fan. A heating chamber cooling device for heat treatment, characterized by gradually cooling an object to be heated in a heating chamber. 2. The heating chamber cooling device for heat treatment according to claim 1, wherein a damper is provided in a duct which connects the low temperature chamber and the vent hole. 3. The heating chamber cooling device for heat treatment according to claim 1, wherein the low temperature chamber is a quenching chamber that follows the heating chamber. 4. The heating chamber cooling device for heat treatment according to claim 1, wherein the low temperature chamber is a cooling chamber subsequent to the heating chamber.