JPH0721389B2 - Heat treatment furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat treatment furnace such as a sintering furnace or a degreasing furnace for producing a sintered body of ceramics, metal or the like.

“Prior Art” In this type of heat treatment furnace, the inclusions, such as wax used as a binder, are generated as gaseous impurities from the object to be treated during the heat treatment, and it is necessary to discharge it from the furnace body. There is. That is, unless the impurities are sufficiently discharged, since they are generally condensable gases, they are cooled on the inner wall surface of the furnace or the wall surface of the heating chamber, and are liquefied or solidified and adhere. Therefore, not only must the maintenance inside the furnace be performed frequently, but the adhered impurities may re-evaporate during the main sintering or the next processing and contaminate the object to be processed.

For this reason, in the prior art, as shown in FIG. 3, for example, a carrier gas is introduced into a furnace a through an introduction pipe b, impurities are exhausted together with the carrier gas by a forced exhaust fan c, and the atmosphere is passed through an exhaust pipe d into the atmosphere. It is emitted as it is, or if it is a combustible impurity, it is burned by a burner e. Alternatively, as shown in FIG. 4, the vacuum pump f sucks the impurities together with the carrier gas to evacuate them, and the trap g provided in the middle of the exhaust pipe d collects the impurities and then releases them into the atmosphere. There is.

[Problems to be Solved by the Invention] However, in the above means, even if the trap g is provided, the trapping efficiency is not always sufficient, and in any case, impurities are released to the atmosphere. There was an environmental health problem.

Further, impurities adhere to the exhaust pipe d, the valve h provided in the middle thereof, the exhaust fan c, and the vacuum pump g, and the pipe furnace is blocked or corroded, or the exhaust fan c and the vacuum pump g are used.
Since it causes a problem that the operation of is blocked, it is necessary to frequently perform maintenance for them.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat treatment furnace which can remove impurities without being released into the atmosphere and can be easily maintained.

"Means for Solving Problems" The present invention provides an inner case capable of maintaining a hermetically sealed state inside a furnace body, heats an object to be processed in the inner case, and treats the object during processing. In a heat treatment furnace in which gaseous impurities such as wax generated from the inside are discharged to the outside of the furnace body from the inside of the inner case, a container-like impurity trap that can be hermetically sealed and has a single inlet at the above While being provided outside the furnace body, an outlet pipe for guiding impurities generated in the inner case to the impurity trap is detachably connected to the inlet of the impurity trap via a valve, It is characterized in that the inside of the inner case and the inside of the trap for trapping impurities are communicated with each other via a lead-out pipe.

[Operation] In the heat treatment furnace of the present invention, the inner case and the impurity trap that are connected by the outlet pipe form one closed container, and the impurities generated from the object to be processed in the inner case are trapped by the outlet pipe. And is collected there.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a furnace body capable of holding a vacuum.
A carrier gas introduction pipe 2 for introducing a carrier gas into the furnace body 1 and a vacuum exhaust pipe 3 for making the inside of the furnace body 1 a vacuum are connected to the furnace body 1. Three
A vacuum pump 5 is connected to the valve via a valve 4.

A heating chamber 6 formed of a heat insulating material is arranged inside the furnace body 1, and an inner case 7 is arranged inside the heating chamber 6. The heating chamber 6 is provided with bangs 9 and 9 which are opened and closed by drive cylinders 8 and 8 on both right and left sides in the drawing, and lids 10 and 10 of the inner case 7 are integrally attached to the insides of these bangs 9 and 9. The inner case 7 can be opened and closed at the same time when the heating chamber 6 is opened and closed. (The chain double-dashed line in the figure shows the state in which the bang 9 is open.) The inner case 7 and its lids 10, 10 are made of a material that can withstand high temperatures, such as a graphite plate. Further, the inner case 7 is configured to be able to maintain an internal sealed state when the lids 10, 10 are closed.

Further, inside the heating chamber 6, heaters 11 ... Are arranged around the inner case 7, and these heaters 11 ...
Is configured to indirectly heat the object to be processed 12 loaded in the inner case 7.

One end of an outlet pipe 13 is connected to the inner case 7, and an impurity trap 15 (hereinafter simply referred to as a trap) is detachably connected to the other end of the outlet pipe 13 via a valve 14. There is. The lead-out pipe 13 connects the inner case 7 and the trap 15 so as to lead out gaseous impurities such as wax generated from the object 12 in the inner case 7 to the trap 15. The inner case 7 and the trap 15 form a closed space by 13. In order to prevent impurities from being cooled and fixed on the inner surface of the lead-out pipe 13, it is desirable that a heat insulating material (not shown) be wound around the lead-out pipe 13.

The trap 15 is formed in a container shape capable of maintaining a closed state, has a single inlet port on its upper part, has a large number of fins 16 attached to its inner surface, and has activated carbon or A chemical adsorbent 17 such as a molecular sieve is stored. This trap 15 is cooled from the surroundings so that the surface temperature of its inner wall surface and the fins 16 ... Is sufficiently lower than the temperature inside the inner case 7, so that impurities trapped inside are trapped. The condensable gas is brought into contact with the cooled inner wall surface and the fins 16 to be liquefied or solidified, and the non-condensable gas can be adsorbed by the chemical adsorbent 17.

Next, a method of using the heat treatment furnace having the above structure will be described. First, the inside of the furnace body 1 is evacuated by the vacuum pump 5, and
The inner case 7 is sealed by closing 9,9 and the lids 10,10. Then, degreasing is performed prior to the main sintering. That is, the outlet pipe
The object 12 to be processed is heated to a predetermined temperature with the valve 14 connected to 13 being opened to evaporate the contents of the object 12 to be processed.
As a result, the gas of impurities such as wax generated from the object to be treated 12 fills the inner case 7 and is also introduced into the trap 15 communicating with the inner case 7 to fill the same. Then, in the trap 15, the gas is liquefied or solidified and adheres to the inner wall surface or the fins 16 which are at a low temperature, or adheres to the chemical adsorbent 17,
As a result, a difference in gas density occurs between the inner case 7 and the trap 15, and the difference in density causes the gas to be sequentially discharged from the inner case 7 into the trap 15.

Therefore, after a lapse of a predetermined time, the condensable gas is collected in the trap 15 in a liquefied or solidified state,
The non-condensable gas is adsorbed by the chemical adsorbent 17 and does not flow back into the inner case 7. Further, since the inner case 7 and the trap 15 are hermetically sealed, the gas does not flow out into the heating chamber 6 or the furnace body 1 and does not diffuse into the atmosphere.

At the time of this degreasing, it is desirable to introduce the carrier gas into the furnace body 1 through the carrier gas introduction pipe 2 so as to maintain the internal pressure of the furnace body 1 slightly higher than the pressure inside the inner case 7. By doing so, it is possible to prevent the gas from flowing out of the inner case 7 even if the sealing degree of the inner case 7 is impaired.

After the impurities are sufficiently removed as described above, the valve 14 is closed to seal only the inner case 7 and the inner case 7 is heated to a higher temperature for main sintering.

Then, at an appropriate time after the above processing is completed, or when a predetermined amount of impurities are stored in the trap 15, the trap 15 is removed from the valve 14 to take out the impurities stored therein, and the chemical adsorbent is also used. Replace 17 and reattach to valve 14. Note that this work can be performed in parallel with the main sintering immediately after the degreasing work is completed if the valve 14 is closed.

As described above, according to this heat treatment furnace, the gas of the impurities generated from the object to be treated 12 during the degreasing process can be removed
And the inside of the furnace body 1 and without trapping the trap 15 out of the valve 14 with the valve 14 open, impurities will not be released into the atmosphere. Can be removed. Moreover, the trap
Since the contact area with the gas is increased by mounting the fins 16 in the inside of the 15, the collection efficiency is improved and the gas can be collected very efficiently. Therefore, it is possible to prevent the inner surface of the furnace body 1, the wall surface of the heating chamber 6, and the object to be treated 12 from being contaminated with impurities, and there is no environmental problem.

Further, since no power is required for removing impurities in this heat treatment furnace, compared with the conventional case where impurities are forcedly exhausted by, for example, an exhaust fan c or a vacuum pump g (see FIGS. 3 and 4). The operating cost can be reduced. Further, the trap 15 is a mere container-like one having only a single inlet port on its upper part, and for example, as shown in FIG. 4, since it is provided in the middle of the exhaust pipe d, two connection ports are required. The trap g has a very simple structure as compared with the conventional trap g. When the impurities collected in the trap 15 are taken out, the valve 14 is closed and the trap 15 is removed from the valve 14. Since it only needs to be performed, operation and maintenance are extremely easy. Further, since the chemical adsorbent 17 can be reused, the operation cost can be further reduced by doing so. The impurities removed from the trap 15 can be recovered and reused if necessary.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above. For example, in the above-described embodiment, the fins 16 ... Are attached to the inside of the trap 15. However, instead of the fins 16 ..., wire nets 18 ... Are provided, and the wire nets 18 ... Similar effects can be obtained by contacting and collecting.

In the above, the fins 16 (or wire mesh
18) was attached and the chemical adsorbent 17 was housed so that both condensable gas and non-condensable gas were collected, but this is not always the case, depending on the type of gas generated. It is also possible to collect only one of them.

Further, when it is desirable to collect the impurities in a liquid state without solidifying them, the trap 15 may be appropriately heated from the outside so that the impurities are not excessively cooled. When it is desirable to solidify and collect as a solid, the trap 15 may be positively cooled from the outside by an appropriate cooling means so that the impurities are rapidly solidified.

Furthermore, it is also possible to use an electrostatic trapping device that traps gas electrically as a trap.

Further, in the above description, the carrier gas is introduced into the furnace body 1 during degreasing to prevent the backflow of impurities, but this is not always necessary if the inner case 7 can be sufficiently sealed.

[Advantages of the Invention] As described above in detail, according to the present invention, a container-like impurity trap that can be hermetically held and has a single inlet at the top is used to remove impurities generated in the inner case. A lead-out pipe for leading to the impurity trap is detachably connected to the inlet of the impurity trap through a valve, and the inside of the impurity trap in the inner case is communicated through the lead-out pipe. Since the configuration is adopted, there is an effect that impurities can be efficiently removed without flowing out from the inside of the inner case and without being released into the atmosphere. In addition, this heat treatment furnace does not require any power for removing impurities and has a simple structure, so that maintenance is easy, and operating costs and maintenance costs can be reduced.

[Brief description of drawings]

1 and 2 are views showing an embodiment of the present invention. FIG. 1 is a sectional view showing a schematic structure of a heat treatment furnace of this embodiment, and FIG. 2 is another structure of an impurity trap. It is a figure which shows an example. FIG. 3 and FIG. 4 are diagrams each showing an outline of the gas removing means in the conventional furnace. 1 ... Furnace body, 7 ... Inner case, 12 ... Workpiece,
13 …… Outlet pipe, 14 …… Valve, 15 …… Impurity trap.

Claims (1)

[Claims] 1. An inner case capable of maintaining a hermetically sealed state is provided inside a furnace body, and an object to be processed is heat-treated inside the inner case, and a gaseous substance such as wax generated from the object to be processed at the time of processing is provided. In a heat treatment furnace in which impurities are discharged from the inner case to the outside of the furnace body, a container-like impurity trap that can be hermetically held and has a single inlet at the top is provided outside the furnace body, and A lead-out pipe for guiding impurities generated in the inner case to the impurity trap is detachably connected to the inlet of the impurity trap via a valve, and is connected to the inner case via the lead-out pipe. A heat treatment furnace characterized by communicating with the inside of an impurity collection trap.