JP2001263957A - Vacuum furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain of a high-quality product by uniformly heating a material to be treated while achieving the quick cooling of the material efficiently. SOLUTION: A plurality of combustion type radiant tube heaters 34 facing the inside of a treating chamber 16 are arranged in a vacuum furnace 10 so as to be placed between heat insulating walls 14 and a material 18 to be treated. Heat transfer plates 36 whose size is set so as to be capable of covering whole of the surface of the material 18, which is opposed to the radiant tube heater 34, are arranged between the radiant tube heaters 34 and the material 18 in the treating chamber 16. Whole of the heat transfer plates 36 is heated by radiation from the radiant tube heaters 34 and whole of the material 18 is heated uniformly by the radiant heat of the heat transfer plates 36. Dampers 40 for regulating and controlling inert gas, which flows into the treating chamber 16, so as to flow toward the side of the material 18 mainly, are arranged at the lower ends of the heat transfer plates 36 so as to be capable of controlling the slanting of the dampers 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum furnace for heating a processed product using a radiant tube heater.

[0002]

2. Description of the Related Art In a vacuum furnace used for powder sintering of various alloy products, firing of ceramic products, etc., a processing chamber surrounded by heat insulating walls is defined in a vacuum vessel. The processed article is configured to be heated using an electric resistance heater.

However, the conventional vacuum furnace using only an electric resistance heater as a heating source has a problem that running costs are increased. Therefore, a proposal has been made to use a heat radiation tube using liquefied natural gas or the like as a fuel, that is, a radiant tube heater as a heating source, which can keep running costs low. The radiant tube heater is also excellent in that the heater can be protected from the evaporant from the processed product.

[0004]

As described above, the radiant tube heater is superior in that the running cost can be reduced as compared with the electric resistance type heater, but the radiant tube heater has a dense arrangement like the electric resistance type heater. Have difficulty. That is, in a furnace such as a vacuum furnace that does not have convective heat transfer and heats a processed product by radiant heat transfer, the difference in heating capacity between the vicinity of the radiant tube heater installation position and the part distant from the installation position is different. And the temperature distribution of the processed product may be non-uniform. In addition, there is a problem in that a high quality product as expected cannot be obtained due to a temperature difference generated when the processed product is heated.

[0005] In the vacuum furnace, when the processed product after heating is cooled in the processing chamber, it is necessary to cool the entire furnace. In the cooling for enhancing the quenching effect, the processed product is rapidly cooled. This is very important. Conventionally, when a processed product is rapidly cooled, an inert gas is supplied into the furnace, and the inert gas is circulated inside and outside the heat insulating wall using a fan provided in the furnace. However, the flow of the inert gas in the processing chamber is not controlled, so that it takes time to cool the processed product.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems inherent in the prior art, and has been proposed to solve the problem suitably. It is an object of the present invention to provide a vacuum furnace capable of obtaining a product and efficiently achieving rapid cooling of a processed product.

[0007]

[MEANS FOR SOLVING THE PROBLEMS]
In order to appropriately achieve the intended purpose, the vacuum furnace according to the present invention is provided with a processing chamber surrounded by a heat insulating wall in a vacuum chamber, and a space between a processing product charged into the processing chamber and the heat insulating wall. In a vacuum furnace provided with a radiant tube heater, a heat transfer plate for improving a uniform temperature distribution of the processed product is disposed between the processed product and the radiant tube heater.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a vacuum furnace according to the present invention will be described below with reference to the accompanying drawings by way of preferred embodiments.

FIGS. 1 and 2 show a vacuum furnace according to an embodiment. In a vacuum chamber 12 of the vacuum furnace 10, a heat insulating material is provided on a holding material made of a metal material. A heat-insulating wall 14 formed in a box shape is stored therein, and a processing chamber 16 is defined by being surrounded by the heat-insulating wall 14. Inside the processing chamber 16, the processed product 1
A mounting table 20 on which the mounting 8 is mounted is arranged, and the processing product 18 mounted on the mounting table 20 is set so as to face substantially the center of the inside of the processing chamber 16. Further, a vacuum pump (not shown) is connected to the vacuum chamber 12, and the inside of the vacuum chamber 12 and the processing chamber 16 can be set to a substantially vacuum atmosphere.

A motor 2 is provided above the vacuum chamber 12.
2 is disposed, and the fan 2 rotated by the motor 22 is provided.
4 faces between the heat insulating wall 14 and the vacuum chamber 12 (outside the heat insulating wall) and circulates an inert gas (furnace atmosphere gas) supplied to the inside of the vacuum chamber 12 when the processing product 18 is cooled. It is configured to As shown in FIG. 1, coolers 26 for circulating cooling water are provided between the vacuum chamber 12 and the heat insulating wall 14 on both left and right sides in the furnace width direction with the heat insulating wall 14 interposed therebetween. It is configured to cool the inert gas circulated by rotation. Openings 2 are provided at the ceiling and the bottom of the heat insulating wall 14, respectively.
8 is formed, and an opening / closing door 30 is disposed at each opening 28 so as to be openable and closable, and the opening / closing door 30 is attached to the vacuum chamber 12.
Is opened and closed via a fluid pressure cylinder 32 disposed outside the device. That is, both doors 30, 3
0 indicates that the openings 28 are closed when the processed product 18 is heated.
1 (FIG. 1), the openings 28, 28 are opened (FIG. 2) at the time of cooling the processing product 18, so that the inert gas cooled by the cooler 26 circulates in the processing chamber 16, so that the processing product 18 is cooled. Is rapidly cooled to the quenching level.

The vacuum furnace 10 includes a vacuum chamber 12.
A plurality of combustion-type radiant tube heaters 34 penetrating through the heat insulating wall 14 and facing the inside of the processing chamber 16 are provided on both sides of the processing product 18 in the furnace width direction with the heat insulating wall 14 and the processing product 1.
8 are arranged so as to extend in the vertical direction along the furnace wall, respectively. That is, in the vacuum furnace 10,
The processing product 18 loaded in the processing chamber 16 is configured to be heated by a plurality of radiant tube heaters 34.

As shown in FIG. 1, the processing chamber 16 is provided between the radiant tube heater 34 located on each side in the furnace width direction of the processing product 18 and the processing product 18 as shown in FIG. A heat transfer plate 36 set to a size capable of covering the entire surface facing the radiant tube heater 34 is provided. The entirety of the heat transfer plate 36 is heated by radiation from the radiant tube heater 34, and the entire processed product 18 is uniformly heated by the radiant heat of the heat transfer plate 36. Further, as shown in FIG. 3, each heat transfer plate 36 is located at a position separated from a position where the radiant tube heater 34 is disposed,
That is, by forming the through hole 38 at a position where the radiation heating capability is low, the temperature distribution of the entire heat transfer plate 36 can be made more uniform. The through hole 38 may be a plurality of holes or a single hole.

At the lower end of each of the heat transfer plates 36, a damper 40 as an adjusting means is disposed so as to be capable of adjusting the tilt. The damper 40 allows the inert gas flowing into the processing chamber 16 from the opening 28 at the bottom. By adjusting and controlling the gas to flow mainly toward the processing product 18, the processing product 18 can be rapidly cooled.

[0014]

Next, the operation of the vacuum furnace according to the embodiment will be described. As shown in FIG. 1, in a state where the openings 28, 28 of the heat insulating wall 14 are closed by opening / closing doors 30, 30, the processing chamber 16 is evacuated to a vacuum atmosphere by a vacuum pump (not shown), and the radiant tube heater 34 is heated. I do. In this case, the radiation from the radiant tube heater 34 is transmitted to the heat transfer plate 36, and the entire heat transfer plate 36 is substantially uniformly heated. Since the heat transfer plate 36 is set to have such a size as to cover the entire opposing side surface of the processed product 18, the radiation of the heat transfer plate 36 heats the entire processed product 18 substantially uniformly. That is, it is possible to suppress the occurrence of a temperature difference when heating the processed product 18 and obtain a desired high-quality product.

As shown in FIG. 3, a through hole 38 is formed in the heat transfer plate 36 at a position away from the position where the radiant tube heater 34 is disposed, so that the heat transfer capability of the heat transfer plate 36 is made uniform. With such adjustment, the temperature distribution of the processed product 18 can be further uniformed.

When the heat treatment of the processed product 18 is completed,
The combustion of the radiant tube heater 34 is stopped, and as shown in FIG. 2, the doors 30, 30 are operated to open the openings 28, 28. Vacuum chamber 1
The inert gas is cooled by contacting the coolers 26, 26 by rotating the fan 24 with the inert gas supplied into the processing chamber 2 through the openings 28, 28. Circulates inside the 16. Opening 28 at the bottom
The inert gas that has flowed into the processing chamber 16 via the heat transfer plate 36 is adjusted and controlled by a damper 40 disposed on each of the heat transfer plates 36 so as to flow mainly toward the processing product 18. Thereby, the processed product 18 is efficiently and rapidly cooled to the quenching level.

Although the embodiment has been described using a combustion type radiant tube heater, an electric resistance type radiant tube heater may be employed. Further, in the embodiment, the damper disposed so as to be capable of adjusting the tilt at the lower end of the heat transfer plate is used as the adjusting means, but is inactivated by a bent portion integrally formed at one end of the heat transfer plate at a predetermined angle. A configuration for adjusting and controlling the gas flow direction may be employed. Further, the heat transfer plate may be made of a punching metal, and the number and arrangement of the through holes may be appropriately set to make the radiation heating capability of the heat transfer plate uniform. However, even if the through holes are not formed in the heat transfer plate, the temperature distribution of the processed product can be made uniform, so that a heat transfer plate without the through holes can be employed.

[0018]

[Experimental Examples] Inventive Example 1 in which the through hole 38 is not provided in the heat transfer plate 36, Inventive Example 2 in which the through hole 38 is provided in the heat transfer plate 36, and a conventional example in which the heat transfer plate 36 is not provided, are treated products Table 1 shows the temperature distribution in the case of heating at a furnace temperature of 1050 ° C. using mold steel and the cooling time required to cool from 1050 ° C. to 400 ° C. In the heat transfer plates 36 of Invention Example 1 and Invention Example 2, the adjustment control is performed by the damper 40 so that the inert gas mainly flows on the processed product 18 side.

[0019]

That is, from the results of this experiment, the heat transfer plate 36
It has been clarified that the provision of the damper 40 improves the temperature distribution and the cooling time as compared with the conventional example. Further, by providing the through holes 38 in the heat transfer plate 36,
It was also confirmed that the uniformity of the temperature distribution of the processed product 18 was further improved.

[0021]

As described above, in the vacuum furnace according to the present invention, by disposing the heat transfer plate between the radiant tube heater and the processed product, the whole of the processed product is heated by the heat transfer plate heated by the heater. Can be heated substantially uniformly to obtain a high quality product. Further, by forming through holes in the heat transfer plate to make the radiation heating capability uniform, it is possible to further achieve uniform heating of the processed product. Further, by providing the heat transfer plate with adjusting means for adjusting and controlling the flow direction of the atmosphere gas in the furnace, there is an effect that the rapid cooling of the processed product can be efficiently achieved.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional side view showing a vacuum furnace according to a preferred embodiment of the present invention in a state where a processed product is heated.

FIG. 2 is a schematic vertical sectional side view showing the vacuum furnace according to the example in a state where a processed product is cooled.

FIG. 3 is a cross-sectional plan view of a main part of a vacuum furnace according to an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Vacuum chamber 14 Heat insulation wall 16 Processing chamber 18 Processed product 24 Fan 28 Opening 34 Radiant tube heater 36 Heat transfer plate 38 Through hole 40 Damper (adjustment means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiharu Shimizu 19-18 Sakuradacho, Atsuta-ku, Nagoya City, Aichi Prefecture Inside Higashi Kuni Gas Co., Ltd. 72) Inventor Hirokazu Matsubara 18 F-term (reference) 4K018 DA32 DA33 4K046 BA08 CC01 4K063 AA07 AA16 CA01 CA03 DA26

Claims (3)

[Claims] A processing chamber (16) surrounded by a heat insulating wall (14) is provided in a vacuum chamber (12), and a processing product (18) charged into the processing chamber (16) and a heat insulating wall (14) are provided. In a vacuum furnace having a radiant tube heater (34) disposed between the treated product (18) and the radiant tube heater (34), a uniform temperature distribution of the treated product (18) is improved. Heat transfer plate (3
A vacuum furnace, wherein 6) is arranged. 2. The vacuum furnace according to claim 1, wherein a through hole is formed in said heat transfer plate so as to have a uniform radiant heating capability. 3. Openings (28, 28) provided in said heat insulating wall (14).
A fan (24) for circulating the furnace atmosphere gas into the processing chamber (16) through the heat transfer plate (36). Adjusting means (4
The vacuum furnace according to claim 1 or 2, wherein (0) is provided.