JPH0611274A - Pulse type gas introduction device - Google Patents

Abstract

(57) [Summary] [Purpose] A processing gas of a predetermined concentration can be effectively brought into contact with the inside of the processed material, the amount of the processing gas used can be saved, and the safety of the furnace can be improved. . [Structure] The processing gas X and the flow gas Y are introduced into the inner and outer spaces S ₁ and S ₂ of the tight box 2 in a pulsed manner almost at the same time, and thereafter, the inner space S of the tight box 2 is introduced.
The control of evacuating ₁ through the exhaust system path 6 is repeated according to the command from the controller 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applicable to various industrial furnaces including a sintering furnace in general, and can control the oxygen content, carbon content, nitrogen content, etc. of the processed material in a pulse system. The present invention relates to a gas introduction device.

[0002]

2. Description of the Related Art For example, in a conventional degreasing / sintering furnace, a treatment for controlling the amount of carbon contained in a treated product may be performed after degreasing and before the start of sintering. That is, it is usual that a certain amount of binder remains in the treated material in the degreased brown body, and in injection molding of stainless steel, such residual carbon is completely disliked, and injection of cemented carbide is avoided. In molding, in order to obtain high strength, the carbon content is required to be contained in a predetermined ratio without excess or deficiency. Under such circumstances, after degreasing and before the start of sintering, a treatment gas such as hydrogen is brought into contact with the treated material to wash away the binder remaining between particles to control the carbon content.

[0003]

By the way, the conventional apparatus for carrying out such a treatment is, from the viewpoint of preventing the situation in which the furnace material such as the heater and the heat insulating material reacts with the processing gas to cause the contamination in the furnace, A first gas introduction system passage opening at a site communicating with the inner space of the airtight tight box; a second gas introduction system passage opening at a site communicating with the outer space of the tight box; It is generally provided with an exhaust system passage for exhausting the inner space of the box.
That is, this gas introduces a processing gas such as hydrogen into the tight box through the first gas introduction system passage and a flow gas such as nitrogen outside the tight box through the second gas introduction system passage. The flow gas is set to a pressure higher than that of the processing gas, and the inner space of the tight box is exhausted through an exhaust system passage in parallel with the introduction of these gases, so that the inside space of the tight box goes from the outer space of the tight box to the inner space. Generates a steady flow of the flow gas, and along this flow, process gas with high risk that is introduced into the inner space of the tight box and wax vapor generated in the inner space of the tight box are outside the tight box. It is designed to be discharged directly to the outside of the furnace through an exhaust system passage without leaking to the space.

However, with such a structure, the processing gas introduced into the inner space of the tight box is always diluted with the flow gas. Therefore, there is a problem that it is difficult to bring the high-concentration processing gas into contact with the processed material. Further, since the concentration of the processing gas in the inner space of the tight box slightly changes depending on the inflow amount of the flow gas, there is a problem that it is extremely difficult to set the concentration. Further, since the processing gas only passes by stroking the surface of the processing object along the flow of the flow gas, there is a problem that it is difficult to impregnate the inside of the processing object with the gas. In addition, such inefficient gas contact requires a large amount of processing gas, which leads to high cost and high risk when the gas is explosive. I also have defects.

The present invention has been made in view of these problems, and it is possible to effectively bring a processing gas having a required concentration into the inside of a processed material, and to save the amount of the processing gas used. It is an object of the present invention to provide a pulse type gas introduction device capable of improving the safety of the furnace.

[0006]

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

That is, the pulse-type gas introduction device of the present invention communicates with the first gas introduction system passage opened at a portion communicating with the inner space of the airtight tight box and the outer space of the tight box. The second gas introduction system passage opened to the site, the exhaust system passage for exhausting the inner space of the tight box, and the first and second gas introduction system passages are opened and closed substantially simultaneously and intermittently in a pulse shape. In addition, it is characterized by comprising control means for controlling the opening of the exhaust system passage while both system passages are closed.

[0008]

According to this structure, when the first and second gas introduction system passages are opened almost simultaneously through the control means,
Predetermined processing gas and flow gas are introduced into the inner and outer spaces of the tight box, respectively. At that time, the concentration of the processing gas in the inner space of the tight box is almost 100%. After that, if the exhaust gas passage is opened through the control means before the processing gas leaks to the outer space of the tight box through the tight box having air permeability, the processing gas in the inner space of the tight box is directly discharged to the outside of the furnace. At the same time, the flow gas gradually flows from the outer space of the tight box into the inner space. Therefore, with this,
The partial pressure of the flow gas with respect to the partial pressure of the processing gas in the inner space of the tight box gradually increases. Then, when most of the flow gas flows from the outer space of the tight box to the inner space, most of the process gas existing in the inner space of the tight box is discharged to the outside of the furnace, so that the flow gas can be followed up. Is also discharged outside the furnace. At this point, the inner and outer spaces of the tight box are evacuated. Then, in the next cycle, the control means closes the exhaust system passage and opens the first and second gas introduction system passages almost at the same time again to introduce a predetermined gas into the inner and outer spaces of the tight box.

Therefore, if such a cycle is repeated, the processed material is vacuum-exhausted to the inside when the exhaust system passage is activated, and then the processed gas is passed through the first gas introduction system passage to the inside of the tight box. When introduced into the space, the processing gas is easily absorbed and impregnated into the inside of the processed material. As described above, according to the present invention, it is possible to breathe the processed material, so that the gas is effectively contacted with the inside of the processed material as compared with the conventional case, and the predetermined processing is appropriately performed. It becomes possible to tighten. Of course, since the existence of the processing gas is limited only to the inner space of the tight box, it is possible to avoid the problem of causing contamination in the furnace. Moreover, since the processing gas can be efficiently brought into contact with the object to be processed in this way,
Gas consumption can be saved, and even if the gas is detonating, the amount used is small and the safety of the furnace can be improved.

[0010]

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

As shown in FIG. 1, a furnace 1 to which this pulse-type gas introduction device is applied has a treatment object W inside a furnace wall 1a.
A tight box 2 is provided which is provided with a lid 2a for inserting / removing and is made of a porous material as a whole and has a certain gap. Then, the tight box 2 is heated by the heater 3 arranged around it.

For such a furnace 1, the pulse-type gas introduction device of this embodiment has a first gas introduction system passage 4, a second gas introduction system passage 5, an exhaust system passage 6, and a control system. And a controller 7 as means.

The first gas introduction system passage 4 is formed by connecting a supply end of a gas cylinder 4a filled with a processing gas X such as hydrogen H ₂ , methane CH ₄ and ammonia NH ₃ to an exhaust system passage 6. A flow rate control valve 4b that controls the flow rate of the processing gas X from the gas cylinder 4a and a valve 4c that opens and closes the system path 4 are serially interposed in the middle thereof, and the tight box 2 is responsive to the control signal a. A processing gas X having a predetermined flow rate is introduced into the inner space S ₁ of the. The second gas introduction passage 5 is formed by connecting the supply end of the gas cylinder 5a filled with the flow gas Y such as nitrogen N ₂ or Ar to the portion penetrating the furnace wall 1a. A flow rate control valve 5b for controlling the flow rate of Y and the system path 5 concerned.
A valve 5c for opening and closing the valve is serially interposed in the middle thereof, and a predetermined flow rate of the flow gas Y is introduced into the outer space S ₂ of the tight box 2 in accordance with the control signal b. The flow rate ratios Q ₁ and Q ₂ of the gases X and Y allowed by the flow rate control valves 4b and 5b are, for example, the volume of the inner space S ₁ of the tight box 2 is V _I , and the outer space S is
_When the volume of ₂ is V _O , it is set to be equal to V _I : V _O. Keep the total pressure below atmospheric pressure. The exhaust system passage 6 has an inner space S of the tight box 2.
₁ is connected to the intake port of the vacuum pump 6a, and a valve 6b that opens and closes the system according to the control signal c is interposed in the middle thereof, and a check valve is provided at a position branched from the upstream of the valve 6b. 6c is attached. Further, in this embodiment, the vacuum pump 6a is installed in the outer space S ₂ of the tight box 2.
An auxiliary exhaust system passage 8 connected to is provided with a valve 8a that operates in response to a control signal d and a mechanical booster pump 8b that are serially interposed in the middle of the valve 8a.

Then, each of the valves 4c, 5c, 6b and 8a.
Are connected to the controller 7. This controller 7
Is constituted by, for example, a microcomputer system, and the first and second gas introduction system passages 4, 5 are provided.
Stores an appropriate sequence control program for controlling the opening and closing of the exhaust system path 6 while closing both system paths 4 and 5 at the same time and intermittently and intermittently. According to the program, the control signals a, b, and
It outputs c and d.

Next, the operation of this embodiment will be described with reference to FIGS.
Will be described with reference to. First, the first and second gas introduction system passages 4 and 5 are opened almost simultaneously through the controller 7, and the processing gas X and the flow gas Y are introduced into the inner and outer spaces S ₁ and S ₂ of the tight box ₂ , respectively. At that time, the concentration of the processing gas X in the inner space S ₁ of the tight box 2 is almost 100%. Of course, the concentration of the flow gas Y in the outer space S ₂ is almost 100%. After that, before the processing gas X flows into the outer space S ₂ through the tight box 2 having air permeability, the controller 7 sets the exhaust system passage 6
Open. Then, the inner space S ₁ of the tight box 2
Process gas X existing in the tight box 2 is pulled by the vacuum pump 6a and directly discharged to the outside of the furnace 1.
Flow gas Y gradually from the outer space S ₂ to the inner space S ₁
Comes in. Therefore, along with this, the partial pressure of the flow gas Y with respect to the partial pressure of the processing gas X in the inner space S ₁ of the tight box 2 gradually increases. Then, the time from the outer space S ₂ tight box 2 inside the space S ₁ is the majority of the flow gas Y has flowed in, outside of the processing gas X most furnace 1 which has been present inside the space S ₁ tight box 2 Then, the flow gas Y is also discharged to the outside of the furnace 1 in the following manner. At this time, the inner and outer spaces S ₁ and S ₂ of the tight box 2 are evacuated. Then, in the next cycle, the controller 7 closes the exhaust system passage 6 and opens the first and second gas introduction system passages 4 and 5 again, and the process gas X is supplied to the inner and outer spaces S ₁ and S ₂ of the tight box 2. And the flow gas Y is introduced.

Therefore, if such a cycle is repeated, the processed material W is evacuated to the inside when the exhaust system path 6 is activated, and then the processing gas X is passed through the first gas introduction system path 4. When being introduced into the inner space S ₁ of the tight box 2, the processing gas X is easily absorbed and impregnated into the inside of the processed material W as shown in FIG.
As described above, according to the present invention, the processed material W can be breathed, so to speak, and as a result, as shown in FIG. 4, the processing gas X simply strokes the surface of the processed material W and passes inside. Compared with the conventional method that does not penetrate, the processing gas X can be effectively brought into contact with the inside of the processing object W, and the predetermined processing can be performed accurately. Of course, the processing gas X is the inner space S of the tight box 2.
_Since it is limited to ₁ , problems that cause contamination in the furnace will also be resolved. Moreover, since the processing gas X can be efficiently brought into contact with the processing object W in this manner, the consumption amount of the processing gas X can be saved, and the gas X is an explosive one such as hydrogen H _2. Moreover, the safety of the furnace can be improved because the amount used is small.

The present invention is not limited to the above-described embodiments, but various modifications can be made without departing from the spirit of the present invention. For example, the effect may be enhanced by slightly shifting the timing of opening and closing the valve. As an example, the flow gas Y may be exhausted by the vacuum pump 6a after the processing gas X is released to the atmosphere through the check valve 6c by prolonging the time for introducing the flow gas. In addition, when it is desired to perform sufficient vacuum exhaust, the door 2a of the tight box 2 may be opened, the valve 8a may be opened, and the auxiliary exhaust system passage 8 may be operated when exhaust has progressed to some extent. Check valves may be added to increase the tight box breathability.

[0018]

As described above, the present invention repeats the operation of introducing the processing gas and the flow gas into the inner and outer spaces of the tight box in a pulsed manner and then evacuating the inner space of the tight box. By doing so, the processed product can be freezing (breathing), and as a result, the gas can be effectively contacted to the inside of the processed product compared to the conventional method, and the predetermined processing can be performed accurately. Become. Of course, since the existence of the processing gas can be limited only to the inner space of the tight box, the contamination in the furnace can be effectively prevented. In addition, since the process gas can be efficiently brought into contact with the object to be processed in this way, the gas consumption can be saved, and even if the gas is explosive, the amount used is small and the safety of the furnace is improved. Can be increased.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing a gas introduction timing in the example.

FIG. 3 is a diagram showing how the processed product breathes according to the embodiment.

FIG. 4 is a view corresponding to FIG. 3, showing a state in which a gas comes into contact with a processed material by a conventional device.

[Explanation of symbols]

S ₁ ... Inner space S ₂ ... Outer space 2 ... Tight box 4 ... First gas introduction system path 5 ... Second gas introduction system path 6 ... Exhaust system path 7 ... Control means (controller)

Claims (1)

[Claims] 1. A first gas introduction system passage opening at a site communicating with the inner space of a tight box having air permeability, and a second gas introduction system opening at a site communicating with the outer space of the tight box. A passage, an exhaust system passage for exhausting the inner space of the tight box, and the first and second gas introduction system passages are opened and closed at substantially the same time and intermittently in a pulse shape, and both passages are closed. A pulse-type gas introduction device comprising: a control unit that controls the opening of the exhaust system passage.