JPH06249578A - Heat treatment furnace - Google Patents

Abstract

PURPOSE:To enable an influence of discharging of carbon to be eliminated even if a graphite furnace is used and to prevent a heating efficiency or a cooling efficiency from being reduced. CONSTITUTION:There are provided a graphite furnace 1 and a container 3 having a lid made of molybdeum arranged within the furnace 1. At least double- contact portions 33 and 34 are formed between the lid 32 of the container 3 and a main body 31, and then a discharging passage 5 is connected to a clearance 35 closed between both contact portions 33 and 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment furnace which can be used as a degreasing furnace, a sintering furnace, a refining furnace and the like.

[0002]

2. Description of the Related Art For example, a sintering furnace is used to sinter a processed product obtained by molding a metal powder into a required shape at a high temperature.
However, in the conventional sintering furnace, there is a problem that the gas generated from the processed material causes contamination in the furnace, damage to the heater, and the like.

Therefore, as one of the improved sintering furnaces, a container having air permeability is arranged in the furnace, a carrier gas is introduced into the outside of the container, and the container is evacuated. What has been developed is one in which a steady flow of a carrier gas having a differential pressure flow from the outside to the inside of a container is formed and the generated gas is prevented from leaking out of the container. With this configuration, it becomes possible to proceed with the sintering while protecting at least the inside of the furnace from the generated gas.

[0004]

However, a problem still remains in such an improved sintering furnace. More specifically, graphite is generally used as a furnace material in the field of furnaces, and such a sintering furnace is no exception. However, this graphite deteriorates by reacting with a processing gas such as H ₂ when heated and heated. Further, it has a property of releasing carbon, and when the sintering progresses in the above-mentioned improved sintering furnace, the carbon released from the furnace flows into the container along with the flow of the differential pressure flow of the carrier gas, and becomes The reaction causes a problem that causes deterioration of product quality.

On the other hand, by making the container a double structure and exhausting both the carrier gas introduced into the furnace and the binder vapor generated inside the inner container to the outside of the furnace through the intermediate gap between both containers, It is considered to prevent the binder vapor from leaking out of the container and prevent the release carbon from entering the container. However, in such a structure, the heater in the furnace has a structure for heating the processed material through the double container, and the heat capacity becomes extremely large, resulting in a large decrease in heating efficiency and cooling efficiency. Derived into a defect.

The present invention has been made by paying attention to such a problem, and even if a graphite furnace is used, the influence of carbon emission can be eliminated and the heating efficiency and cooling efficiency can be lowered. The purpose of the present invention is to provide a heat treatment furnace in which it is prevented.

[0007]

The present invention adopts the following constitution in order to achieve the above object.

That is, the heat treatment furnace according to the present invention comprises a graphite furnace and a container with a lid made of metal or ceramics which is arranged in the furnace, and at least a double layer is provided between the lid of the container and the main body. It is characterized in that a contact portion is formed, and an exhaust system passage is connected to a gap closed between both contact portions.

[0009]

With such a structure, when the processed product is housed in the container and the lid is closed, a certain sealing effect is achieved, though not completely, at the contact portion. Then, when the gap of the contact portion is exhausted through the exhaust system passage, a flow of gas flowing from the inside of the furnace into the gap through the contact portion and a flow of gas from inside the container toward the gap through the contact portion are generated. The gas that has entered the gap does not flow backward and enter the space of the other party, and is discharged directly to the outside of the furnace through the exhaust system passage. Further, since the container is made of metal or ceramics, carbon emission does not occur. Therefore, when the present invention is applied to, for example, sintering, it is possible to simultaneously prevent the generated gas from leaking into the furnace and the released carbon from entering the container.

Further, according to the present invention, since only the space between the lid and the main body of the container has a double structure, the increase of the heat capacity should be suppressed to an extremely small value as compared with the case where the entire container has a double structure. You can

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

This heat treatment furnace is used, for example, in a sintering process, and is formed by surrounding the inside of a graphite furnace 1 with a heat insulating material 2, and arranging a container 3 with a lid inside the heat insulating material 2. The container 3 is made of Mo (molybdenum) composed of a main body 31 and a lid 32. An upward U-shaped groove 31a is formed around the outer edge of the upper end of the main body 31, and a peripheral edge of the lower surface of the lid 32 is formed. A shielding plate 32a is provided protruding from the groove 31a so as to partially partition the inside thereof. When the lid 32 is attached to the main body 31, double contact portions 33 and 34 are formed between the main body 31 and the lid 32.
An annular gap 35 is closed between 34. The lid 32 can be opened and closed by the drive mechanism 4 outside the furnace together with the door 21 of the heat insulating material 2.

A valve 51 and a mechanical booster pump 5 are provided in the annular gap 35 between the contact portions 33 and 34.
2 and the oil rotary vacuum pump 53 are directly connected to the exhaust system passage 5.

A heater 6 for heating the container 3 is arranged around the container 3, and a first gas introduction system passage 7 for introducing H ₂ as a processing gas into the container 3 is provided.
A second gas introduction system passage 8 for introducing N ₂ as a carrier gas is provided in the furnace 1.

The furnace 1 is connected to another exhaust system passage 9 in which a valve 91, an oil diffusion pump 92 and a valve 93 are arranged in series, and the end of the exhaust system passage 9 is a mechanical booster pump. It is connected upstream of 52. Also,
The container body 31 is placed on a hearth (not shown).

In such a structure, the heat insulating door 21 and the container lid 32 are opened together with the furnace lid, and the processing object W requiring sintering is accommodated in the container body 31. Then, the drive mechanism 4 is operated to close the heat insulating door 21 and the lid 32. At this time, the groove 31a of the container body 31 is closed by the lid 32, and a gap 35 having a certain degree of hermeticity is formed between the contact portions 33 and 34. Then, the heater 6 and the exhaust system passage 5 are operated to introduce H ₂ and N ₂ into the container 3 and the furnace 1 through the gas introduction system passages 7 and 8, respectively. As a result, the flow of H ₂ from inside the container 3 toward the gap 35 via the contact portion 33,
N ₂ flowing into the gap 35 from inside the furnace 1 through the contact portion 34
And the flow of. At this time, H ₂ is mixed with the gas generated from the processed material W, and N ₂ is mixed with carbon released from the inner wall of the furnace 1 (since the container 3 is made of Mo, carbon is not released). Absent). The H ₂ , N _{2 and the} like that have entered the gap 35 do not flow back into the other space, that is, the inside of the furnace 1 or the vessel 3, and the generated gas and the released carbon are directly passed through the exhaust system passage 5 through the furnace 1 directly. It can be discharged outside. Therefore, in this configuration, it is possible to reliably prevent the generated gas from leaking into the furnace 1 and the released carbon from entering the container 3.

Further, in this embodiment, only the space between the lid 32 and the main body 31 of the container 3 has a double structure, and all other parts are single-layered. Therefore, when the whole container 3 has a double structure. In comparison with the above, the increase in heat capacity of the heater 6 is extremely small. For this reason, this furnace uses
It is possible to prevent the deterioration of the quality of the above, and at the same time, effectively prevent the deterioration of efficiency during heating and cooling.

Further, in the case of the illustrated example, by opening the lid 32 of the container 3 and operating the other exhaust system passage 9, there is an accompanying effect that the efficiency at the time of initial exhaust and cooling can be improved.

The specific construction of each section is not limited to the illustrated example. For example, in the above embodiment, the contact portion 3
Although the gap 35 between 3 and 34 is partitioned by the shield plate 32a, the shield plate may be removed as shown in FIG. Further, the exhaust system passage 5 is optional such as opening at the bottom of the gap 35 as shown. Further, as shown in FIG.
It is also effective to configure 03 with a bell-shaped lid 132 and a two-plate main body 131. In this case, the downward groove 132a provided in the lid 132, each plate 131a of the main body 131,
The contact portions 133 and 134 may be formed between the contact portions 133 and 134, respectively. When such a configuration is adopted, the main body 132 can also serve as a hearth and the exhaust system passage 105 and the introduction system passage 107 can be connected through the hearth portion, so that the number of constituent elements can be reduced and the furnace can be simplified. It works well when trying. In addition, metal or ceramics other than Mo is used as the material of the container, air or O ₂ other than H ₂ is used as the processing gas,
Various modifications such as the use of N ₂ and Ar are possible without departing from the spirit of the present invention.

[0020]

As described above, in the heat treatment furnace of the present invention, a container with a lid made of metal or ceramics is arranged in the graphite furnace, and at least a double contact portion is provided between the lid of the container and the main body. Is formed, and the exhaust system path is connected to the gap between both contact portions. Therefore, the gas in the furnace and the gas in the container can be differentially exhausted through the exhaust system passage,
It is possible to prevent the gas generated in the container from leaking into the furnace and the carbon discharged into the furnace from entering the container at the same time. Moreover, since only the space between the lid and the main body of the container needs to have a double structure, the increase in heat capacity is suppressed to an extremely small value as compared with the case where the entire container has a double structure, and the decrease in heating efficiency and cooling efficiency is prevented. There is a protective effect.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part showing another embodiment of the present invention.

FIG. 3 is an overall sectional view corresponding to FIG. 1 showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Furnace 3, 103 ... Vessel with lid 5, 105 ... Exhaust system passage 33, 34, 133, 134 ... Contact part 31, 131 ... Main body 32, 132 ... Lid

Claims (1)

[Claims] 1. A graphite furnace, and a container with a lid made of metal or ceramics arranged in the furnace.
A heat treatment furnace characterized in that at least a double contact portion is formed between a lid and a main body of the container, and an exhaust system passage is connected to a gap closed between the both contact portions.