JPH0577957B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a sintering furnace that can perform a dewaxing process and a sintering process in an integrated manner.

[Prior Art] Currently, many sintering furnaces have an internal structure in which a graphite box is placed inside to separate the inside of the furnace into a heating space and a working space. . This is because a large amount of impurities such as wax vapor evaporate from the processed material during the dewaxing process that is carried out as a pre-sintering treatment when the processed material (powder molded product) is placed in a graphite box and subjected to a series of treatments. This is because it is effective in avoiding the problem of gas adhering to furnace materials such as the heater, heat insulating material, and furnace walls and contaminating the inside of the furnace.

[Problems to be Solved by the Invention] Incidentally, in this type of sintering furnace, forced cooling may be performed after completion of sintering for the purpose of hardening the processed material. For this reason, general-purpose sintering furnaces are usually equipped with a cooling mechanism that uses either an external cooling method or an internal cooling method. However, in the external cooling method, a water jacket is installed outside the graphite box, and the material to be processed inside is indirectly cooled by flowing cold water through the water jacket, which results in poor cooling efficiency. There is a drawback that it takes a long time to reach the so-called temperature. In addition, the internal cooling method involves attaching an opening/closing mechanism to the lid of the Graphite box, and operating the opening/closing mechanism during cooling to communicate the inside of the box with the outside of the box. Since the purpose is to circulate gas through the communication space of the box and thereby cool the processed materials placed inside the box, there is a space for circulating gas inside and outside the box, an opening/closing mechanism, a cooling fan, etc. This has the disadvantage that it requires a large amount of space, making the furnace larger and making it extremely expensive.

The present invention has been made in view of these problems, and aims to realize a sintering furnace that enables cooling in a short time and does not increase the size of the furnace or increase costs. There is.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the sintering furnace of the present invention is shown in FIGS. 1 and 2.
As schematically shown in the figure, a processing case 2 is arranged on a hearth 1a fixedly installed in a furnace 1, and an outer space _S1 of this processing case 2 is connected to a cooling circuit _l1 outside the furnace 1.
(a circuit connecting between a to d) to form a first gas circulation system path S ₁ →l ₁ →S ₁ . The inner space S ₂ is connected to the cooling circuit l ₂ (circuit connecting b to e) outside the furnace 1 to form a second gas circulation system path S ₂ →
l ₂ →S ₂ , and a pair of gas inlet/output paths 5a and 5b are provided, and the second gas circulation path S ₂
→l ₂ →S ₂ The present invention is characterized in that at least gas is discharged from the processing case 2 through the hearth 1a.

In particular, when processing small molded products, as shown in the figure, the inside of the processing case 2 has a multi-shelf structure, and the inflowing gas is passed through an appropriate internal channel provided in the processing case 2 to each shelf. It is effective to have a configuration that allows the liquid to be ejected uniformly between the areas 2a.

[Function] With this kind of structure, the gas circulation path
By circulating the cooling gas through S ₁ → l ₁ → S ₁ and S ₂ → l ₂ → S ₂ , the processing case 2 is forced to be cooled from the inside and outside at the same time. The gas comes into contact with the object to be treated and directly cools the object. Therefore, the present invention can exhibit a much greater cooling effect than conventional furnaces! Moreover, the cooling circuit
l ₁ and l ₂ may be placed outside the furnace 1 as shown in the figure,
The furnace 1 does not become larger or more complicated. Particularly in the processing case 2 shown in the figure, which has a multi-shelf structure where indirect cooling is difficult, the cooling efficiency is significantly improved through the action of the gas described above.

Furthermore, since the gas from the processing case 2 in the second gas circulation path S ₂ →l ₂ →S ₂ is led out through the hearth 1a, there is no need to separately incorporate piping, etc.
Existing equipment can be used effectively. Furthermore, since the present invention is constructed entirely by gas cooling, it is possible to share a portion of the cooling circuit outside the furnace 1, thereby increasing equipment efficiency.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIGS. 3 and 4, in this sintering furnace, a graphite hearth 17 is fixed via graphite supports 16 in a furnace 13 in which a heat insulating material 12 is attached to the inner wall of a furnace shell 11. It is set up. A hermetically sealed processing case 18 made of graphite is placed on the hearth 17.

As shown in an enlarged view in FIG. 5, the processing case 18 is box-shaped and includes a bottom plate 19, side plates 20, and a top plate 21. Set in positioning state. The inner space S ₂ of the processing case 18 is divided into left and right sides by a hollow partition plate 22 . Grooves 20a extending vertically are recessed in several places at appropriate intervals on the inner surface of the side plate 20.
A shelf board holder 23 having protrusions 23a at a predetermined pitch in the longitudinal direction is attached to a. Moreover, protrusions 22a extending horizontally at the same pitch as the protrusions 23a are formed on both sides of the partition plate 22, and a plurality of shelf boards 24 are constructed between these protrusions 22a and each of the protrusions 23a. I'm starting to be able to do it.

On the other hand, the protrusion 23a of the shelf holder 23 is provided with a gas ejection hole 23b that communicates with the groove 20a of the side plate 20. It communicates with a gas port 19b opened on the side of the bottom plate 19 through a gas reservoir 19a provided therein. The gas port 19b is connected to a terminal end 25a of a graphite pipe 25, which is a gas introduction/input line. Starting end 25b of graphite pipe
is the gas inlet 2 installed through the furnace 13
5c.

Further, each protrusion 22a of the partition plate 22 is provided with a gas outlet 22b, and these gas outlet ports 22b open into the hollow portion 22c of the partition plate 22. The hollow portion 22c communicates with an outlet 19c bored in the bottom plate 19, and is further connected to the starting end 2 of a graphite pipe 26, which is a gas lead-in/output line connected to the hearth 17.
6a, and the terminal end 26b of this graphite pipe is connected to a gas outlet 26c installed through the furnace 13.

Furthermore, a pair of gas inlet/outlet ports 2 are formed through the furnace 13 at positions facing each other with the processing case 18 in between.
7 and 28 are attached.

Then, in the sintering furnace having such a structure, the first
Cooling circuits l ₁ and l ₂ similar to those shown in the figure are connected. That is, the cooling circuit _l1 has terminals a~
Between b, solenoid valve 6a, cooler 3a, fan 3b
A solenoid valve 6b is interposed between the terminal a and the gas inlet/outlet 28, and the terminal d connected to the gas inlet/outlet 27. In addition, the cooling circuit _l2 is formed by interposing a solenoid valve 6c between the terminals b to e in addition to the solenoid valve 6a, cooler 3a, and fan 3b, which are commonly used as described above, and connects the terminal b to the gas discharge port 26c. Connect terminal e to gas inlet 25
I am trying to connect to c.

In such a configuration, the electromagnetic valves 6a, 6
b, 6c and start the cooler 3a and fan 3b, the gas circulation system paths S ₁ → l ₁ → S ₁ and S ₂ → l ₂ →
Cooling gas will begin to circulate through S ₂ .
Specifically, the gas flowing into the space S ₁ from the gas outlet/outlet 27 flows along the outer wall of the processing case 18 and passes through the gas outlet/outlet 2 provided at the opposite position.
8, and after being cooled in the cooling circuit _l1 outside the furnace 13, the gas flows out from the gas inlet/outlet 27 again into the space.
Flowed into _S1 . Further, the gas introduced from the gas inlet 25c flows through the graphite pipe 25, the gas port 19b, the gas reservoir 19a, and the side plate groove 20a, and then enters the inner space _S2 of the processing case 18 from each gas ejection hole 23b. It begins to spray evenly between the shelf boards 24. After flowing along the shelf board 24, the gas outlet 22b provided at the opposite position
It passes through the graphite pipe 26 and flows out of the furnace 13 from the gas outlet 26c. Thereafter, it is cooled in the cooling circuit l ₂ and flows into the space S ₂ again through the same path.

When the cooling gas is circulated in this way, the processing case 18 is forcibly cooled from the inside and outside at the same time. In particular, the gas that has flowed into the inner space _S2 of the processing case 18 comes into contact with the object to be processed. The processed material will be directly cooled. Therefore, the sintering furnace of this embodiment can exhibit a much greater cooling effect than conventional ones, and as a result, it is possible to cool the processing case 18 and the processing object in a short time. . Moreover, the cooling circuits l ₁ , l ₂
can be placed outside the furnace 1 as shown,
Since there is no need to bring a conventional fan or opening/closing mechanism into the furnace 13, the furnace 13 can be effectively downsized, and costs can be reduced accordingly. Part of the gas output from the hearth 17
The fact that the training is carried out internally is based on the same idea. In addition, conventional technology includes a cooling mechanism that uses _H2 gas, which has the risk of explosion.
The illustrated sintering furnace can be said to be safe in that it does not use such gas. Furthermore, since this device performs internal cooling and external cooling using the same gas circulation,
Part of the gas supply circuit can be shared outside the furnace, increasing equipment efficiency and further promoting simplification and cost reduction.

Although one embodiment of the present invention has been described above,
The cross-sectional shape of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As explained above, the sintering furnace of the present invention is configured to perform a circulation in which gas cooled outside the furnace is supplied to the processing case inside the furnace from inside and outside, and is guided outside the furnace again for cooling. Therefore, the existing furnace can be used as is without major modifications, and the excellent effect of enabling short-term cooling inside the furnace without increasing the size of the furnace or increasing costs can be achieved. Therefore, it is extremely useful when applied to processing cases where the lid cannot be opened or closed when placed inside the furnace. Furthermore, since the entire process is performed using only gas cooling, it becomes easy to improve equipment efficiency by sharing part of the cooling circuit outside the furnace. Furthermore, the fact that gas is led out from at least the processing case in the second gas circulation path through the hearth can also contribute to simplifying the structure and reducing costs.

[Brief explanation of the drawing]

1 and 2 show the configuration of the present invention, and the first
The figure is a cross-sectional view, and FIG. 2 is a longitudinal cross-sectional view. 3 to 5 show an embodiment of the present invention, in which FIG. 3 is a cross-sectional view, FIG. 4 is a longitudinal sectional view, and FIG. 5 is a partially enlarged view of FIG. 3. 1,13...furnace, 1a,17...hearth, 2,1
8... Processing case, 4a, 4b, 27, 28...
Gas lead-in/outlet inlet, 5a, 5b, 25, 26...Gas lead-in/outlet system path, _S1 ...outer space, _S2 ...inner space,
l ₁ , l ₂ ...cooling circuit, S ₁ →l ₁ →S ₁ ...first gas circulation path, S ₂ →l ₂ →S ₂ ...second gas circulation path.

Claims (1)

[Claims] 1. A processing case is disposed on a hearth fixed in the furnace, and a pair is provided in the furnace for connecting the outer space of the processing case to a cooling circuit outside the furnace to form a first gas circulation path. and a pair of gas lead-in/output passages for connecting the inner space of the processing case to a cooling circuit outside the furnace to form a second gas circulation system passage; A sintering furnace characterized in that gas is led out from at least the processing case in the gas circulation system through the hearth.