JPH0264391A - Vacuum heat treatment furnace - Google Patents

Abstract

PURPOSE:To reduce the amount of consumed gas remarkably and prevent a work to be treated from being mixed with impurities such as heat insulating material and the like by a method wherein the sealing of a tray is permitted to make different gas to flow into the inside and the outside of the tray while an evacuating mechanism is connected so as to permit the evacuation of the inside of the tray. CONSTITUTION:A work to be treated 23 is inserted into the recess of a tray 24 at the outside of a furnace and, thereafter, the tray is inserted into the furnace to set it onto a tray supporting column. The evacuations of the tray 24 and the inside of the furnace are effected simultaneously through two series of evacuating systems 27, 27'. After the evacuation, reducing gas or reacting gas is introduced into the tray 24 through a gas introducing system 26 while heating it by a heater 22. The introduced gas flows through the inside of the tray 24 and applies reduction or various reactions on the work 23, then, is discharged out of the furnace through the evacuating system 27. The reducing gas or the reacting gas flows out of a discharging port 31 uniformly and, therefore, the reaction for the work 23 may be effected uniformly. The gas makes contact with the work uniformly in the tray 24 and, therefore, the reaction will never be advanced partially. After finishing the treatment, cooling gas is made to flow forcibly against the outer peripheral surface of the tray 24 by a forced cooling mechanism. There may be no possibility that the work to be treated 23 is scattered by the cooling gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vacuum heat treatment furnace such as a reduction furnace or a reaction furnace that uses gas when heat treating a processed material in a vacuum state.

(Prior Art) An example of a conventional vacuum heat treatment furnace will be explained with reference to the accompanying drawings. FIG. 4 shows an example of a conventional vacuum heat treatment furnace, which is an internal heating type furnace. Here, the vacuum heat treatment furnace includes a furnace body 2 lined with a heat insulating material 1, a heater 3 placed inside this furnace body 2, and a heater 3 placed inside this furnace body 2 for putting the processed material 4 therein. It is comprised of a tray 5, a gas introduction system 6 for introducing reducing or reaction gas into the furnace body 2, an exhaust system 7 for discharging the gas inside the furnace body 2, and the like. In the gas introduction system 6, a cylinder 8 filled with reducing or reaction gas is connected to a valve 9.
It is connected to a nozzle 11 in the furnace body 2 via a flow rate control valve IO. On the other hand, the exhaust system 7 is connected to a mechanical booster pump 12 and an oil rotary pump 13, and discharges the gas inside the furnace body 2 to the outside.

In the heat treatment furnace configured as described above, the material to be treated 4 is placed in the tray 5, then placed in the furnace and sufficiently exhausted by the exhaust system 7. After that, heating is started by the heater 3, and reduction or reaction gas is supplied from the gas introduction system 6. will be introduced.

This introduced gas flows through the furnace as shown by the arrow in the figure, acts on the treated material 4, undergoes reduction and various reactions (chemical, etc.), and then
It is discharged from the furnace through the exhaust system 7.

FIG. 5 shows another configuration example of a conventional vacuum heat treatment furnace, which is an external heating type furnace. Here, the vacuum heat treatment furnace uses a heat insulating material l
, a heater 3, a tray 5 for holding the processed material 4 placed in the furnace body (retort) 2, and a furnace body (retort).
It is comprised of a gas introduction system 6 for introducing reducing or reaction gas into the furnace 2, an exhaust system 7 for exhausting the gas inside the furnace, and the like. In the gas introduction system 6, a cylinder 8 filled with reducing or reaction gas is connected to a nozzle 11 in the furnace via a valve 9 and a flow control valve 10. On the other hand, the exhaust system 7 is connected to a mechanical booster pump 12 and an oil rotary pump 13 to exhaust the gas inside the furnace to the outside. In a heat treatment furnace having such a configuration, as shown in FIG. 4, After the material to be treated 4 is placed in the tray 5, it is placed in the furnace and sufficiently exhausted by the exhaust system 7, after which heating is started by the heater 3, and a reducing or reaction gas is introduced from the gas introduction system 6. The introduced gas flows through the furnace as shown by the arrow in the figure, acts on the treated material 4, undergoes reduction and various reactions (chemical, etc.), and is then discharged from the furnace through the exhaust system 7.

(Problems to be Solved by the Invention) By the way, the above-mentioned conventional vacuum heat treatment furnace had the following drawbacks.

+11 Since the gas for reduction or reaction is passed throughout the furnace, a large amount of gas is required, the cost of the gas consumed increases, and the overall running cost becomes expensive.

(2) In the internal heating type furnace shown in Figure 4, the heat insulating material used in the furnace body scatters, and this scattered heat insulating material mixes into the processed material, causing product defects. Met. Therefore, it is possible to consider a method of making the heat insulating material metal, but Mo is used in high-temperature furnaces.

Since it is necessary to use expensive materials such as Ta and W, there is a drawback that the initial cost of the vacuum heat treatment furnace is too high.

(3) The external heating type furnace shown in Figure 5 is effective in preventing the above-mentioned drawback of insulating material being mixed into the processed material, but the furnace body (retort) material is made of expensive materials. had to be used, which had the disadvantage of increasing the initial cost of the equipment. Also, regarding the furnace body (retort) material, 1
There are almost no products that can be used industrially at temperatures above 000°C.
There were temperature restrictions. Furthermore, cracks in the retort would be very dangerous if 11□ or the like was used as the reaction gas.

(4) When flowing reduction or reaction gas into the furnace, the gaps between the trays and between the trays and the surroundings are uneven, resulting in a difference in gas flow rate. There were cases where there was a difference in reaction speed depending on the tray that was not used.

(5) When cooling the processed material after the completion of the treatment, if the processed material is powder or the like, it may scatter if the flow rate of the cooling gas is high. For this reason, slow cooling was required, and the cooling time took about 5 to 10 hours, which was a factor that significantly reduced productivity.

The purpose of the present invention has been made in view of the above-mentioned drawbacks of the conventional technology.It is an object of the present invention to reduce running costs by significantly reducing the amount of gas used for reduction or reaction, and to reduce impurities such as heat insulating materials in the processed material. The object of the present invention is to provide a vacuum heat treatment furnace that does not contain any contaminants.

(Means for solving the burden) In order to achieve the above object, the vacuum heat treatment furnace of the present invention has the following features:
a sealable tray 7; a gas supply mechanism that supplies gas into the tray; and a gas supply mechanism that supplies gas into the furnace;
a gas exhaust mechanism that exhausts gas from inside the tray and inside the furnace;
It is characterized by comprising a heating mechanism disposed around the tray.

(Function) As described above, according to the vacuum heat treatment furnace of the present invention, the tray can be sealed, allowing separate gases to flow inside and outside the tray, and the exhaust mechanism is designed so that the inside of the tray can also be evacuated. Because they are connected, reduction or reaction can be carried out only around the object to be processed in the tray, allowing for effective processing. Furthermore, since the tray is sealed, it is possible to prevent impurities from entering or scattering.

(Example) An example of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of a vacuum processing furnace of the present invention. Here, the vacuum heat treatment furnace includes a furnace body 21 lined with a heat insulating material 20, a heater 22 disposed inside this furnace body 21,
Similarly, a tray 24 for holding the processed material 23 placed inside this furnace body 21 and a gas introduction system 2 for introducing an inert gas
5, a gas introduction system 26 for introducing reducing or reaction gas into the tray, and two exhaust systems 27 and 27' for discharging gas from the furnace and the tray. In the gas introduction system 26, a cylinder 28 filled with a reducing or reaction gas is connected to a discharge port 31 in the tray via a valve 29 and a flow control valve 30. In the gas introduction system 25, a cylinder 32 filled with inert gas is connected to a nozzle 35 in the furnace via a valve 33 and a flow control valve 34.

On the other hand, the exhaust system 27.27' has a mechanical booster pump 36.36' and an oil rotary pump 37.37' connected in series, and exhausts the gas inside the furnace and the tray to the outside. Tray 24.24° is tray support 38a, 3
8b, and communicate with the gas introduction system 26 and exhaust system 27, respectively. Then, a lid 2ta is placed on the top of the tray 24, and the recessed portion of the tray 24 is closed and hermetically sealed.

FIG. 2 is a partially cutaway perspective view showing the tray 24 of the present invention. A gas introduction system 26 is installed on one side wall of the tray 24.
A cavity 24c is bored for connection to the
A plurality of discharge ports 31 are provided toward the recessed portion of the tray 24. Further, a discharge port 24b for discharging the gas discharged from the discharge port 31 is provided on the opposite side wall of the tray 24.
A cavity 24d is provided with a plurality of cavities and is connected to the exhaust system 27.
is connected to. By stacking a plurality of trays 24, the upper and lower spaces [24C and 24d] communicate with each other and are connected to a gas introduction system 26 and an exhaust system 27, respectively. In the case of FIG. 1, a state in which three trays 24 are stacked is shown.

In the vacuum heat treatment furnace configured as described above, the workpiece 23 is placed in the recess of the tray 24 outside the furnace, and then placed inside the furnace and set on the tray support. Next, the two exhaust systems 27.27
At the same time, the tray 24 and the inside of the furnace are evacuated. After discharge,
A reducing or reaction gas is introduced into the tray 24 through a gas introduction system 26 while being heated by a heater 22 . This introduced gas flows within the tray 24 as shown by the arrow in the figure, acts on the processed material 23, undergoes reduction and various reactions (chemical, etc.), and then
The exhaust system 27 exhausts the gas out of the furnace. At this time, the reducing or reaction gas may also be flowed from the gas introduction system 25. Since the reducing or reaction gas uniformly flows out from the discharge port 31, the reaction with the processing material 23 can be performed uniformly. In other words, since the gas uniformly contacts the processed material within the tray 24, some reactions will not proceed too much.

After the processing is completed, the shutter 39 is opened as shown in FIG. 3, and the tray 2 is
Cooling gas is forced to flow on the outer peripheral surface of 4.

At this time, since the tray 24 is sealed, there is no fear that the processing object 23 in the tray 24 will be scattered by the cooling gas.

In general, the treated material for reduction or reaction is often in the form of small particles or powder in order to increase the surface area and increase the reaction area.

What should be cooled here is the processed material, but the tray 24 has an extremely larger heat capacity, and if the tray 24 is cooled, the processed material can be easily cooled. In this way, in this example, the cooling time after completion of the treatment could be significantly shortened. In other words, the cooling time, which conventionally took 5 to 9 hours, can be reduced to 0.5 to 1 hour. Therefore, productivity can be improved by shortening the processing time of the vacuum heat treatment furnace.

After cooling, the tray 24.24° is removed from the furnace and prepared for the next processing step.

(Effects of the Invention) As explained in detail above, the vacuum heat treatment furnace according to the present invention has high reaction efficiency. ,
The amount of gas flowing through the tray can be as small as 1. Therefore, running costs can be significantly reduced.

Further, the amount of gas flowing around the outer circumference of the tray may be small because the pressure outside the tray is lower than the pressure inside the tray, and there is no problem even if the gas flows from the inside of the tray to the outside.

Furthermore, since the processed material is stored inside the tray, a highly pure product can be manufactured without contaminating impurities from the furnace material (mainly the insulation material) even during heating and cooling.

In other words, high-quality products that could only be achieved with an external heating furnace can now be manufactured using an internal heating furnace, and the initial cost of the vacuum heat treatment furnace can be reduced.

Furthermore, unlike external heating type furnaces, there is no need to use special materials with high heat resistance for the furnace material, so the initial cost of manufacturing the furnace does not increase.

On the other hand, since the gas flow in the tray can be made uniform by the gas discharge ports and exhaust ports provided in the tray, reactions such as reduction can be made uniform.

Furthermore, since the cooling time after the processing is completed can be significantly shortened, productivity can be improved by shortening the cycle time.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is a sectional view showing an example of the vacuum heat treatment furnace of the present invention, Figure 2 is a partially cutaway perspective view of a tray placed in the vacuum heat treatment furnace, and Figure 3 explains the principle of cooling the tray after the heat treatment is completed. 4 is a longitudinal sectional view showing an example of a conventional vacuum heat treatment furnace, and FIG. 5 is a longitudinal sectional view showing another example of a conventional vacuum heat treatment furnace. In the figure, 20...Insulating material 21... Furnace body 22... Heater 23... Processing material 24... ...Tray 25.26 ...Gas introduction system 27.27° ...Exhaust system 28 ...Cylinder 29.33 ...Valve 30.34... ...Flow rate control valve 31...Discharge port 35...-Nozzle 36...Mechanical booster pump 37...Oil rotation Pump In the drawings, the same reference numerals indicate the same or corresponding parts. Figure 1 Patent applicant: Japan Vacuum Technology Co., Ltd. Figure 2 Figure 4I21 Figure 3 Figure 5

Claims (1)

[Claims] a sealable tray; a gas supply mechanism that supplies gas into the tray; and a gas supply mechanism that supplies gas into the furnace;
a gas exhaust mechanism that exhausts gas from inside the tray and inside the furnace;
A vacuum heat treatment furnace characterized by comprising a heating mechanism disposed around a tray.