JPH0641610A - Vacuum degreasing and sintering furnace and degreasing method using the furnace - Google Patents

Abstract

PURPOSE:To provide a vacuum degreasing and sintering furnace capable of shortening the process, saving energy and reducing cost, capable of efficiently removing plural kinds of binders and without developing rancidity in sintering. CONSTITUTION:Gaseous and liq. binders generated from a low-m.p. binder when a material 3 to be sintered contg. the binders and arranged in a heating chamber 4 is heated are discharged through a discharge pipe 6. The liq. binder is recovered in a recovery device 7, the gaseous binder is introduced into a trap 8 through a first pipeline 11 and collected, and further a gaseous binder generated from a high-m.p. binder when the material 3 is heated to a higher temp. is introduced into a combustion device 9 through a second pipeline 16 and burned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sinters a material to be sintered in which a binder is mixed with metal powder, ceramic powder, etc.
In addition, the present invention relates to a vacuum degreasing and sintering furnace that removes a binder and degreases it during sintering and a degreasing method using the same, and in particular, a MIM (Metal I) using a mixture of plural kinds of binders.
The present invention relates to a vacuum degreasing sintering furnace for injection molding and a degreasing method using the same.

[0002]

2. Description of the Related Art When sintering metal powder, ceramic powder, etc., the material to be sintered, which is a mixture of these powders and a binder, is first charged into a degreasing furnace dedicated to degreasing and the binder is vaporized. Alternatively, a technique is adopted in which the material is heated to a melting temperature range to be degreased, and then this material is transferred to a sintering furnace and further heated to a sintering temperature in a higher temperature range for sintering.

[0003]

However, since it is necessary to separately prepare the furnaces for degreasing and sintering in this way, the scale of the equipment becomes large and the equipment cost becomes high. In addition, after degreasing, the temperature in the degreasing furnace needs to be cooled to around room temperature in order to take out the sintered material, which complicates the process, increases energy consumption, and causes a problem of high running cost. It was

In particular, in a vacuum degreasing and sintering furnace for MIM in which a plurality of kinds of binders are mixed and used, since the binders have different melting points, it is possible to remove all the binders within a certain temperature range. It was difficult. Further, when the high melting point binder remains in the material to be sintered, there is a problem such as a bad odor due to exhaust gas generated by decomposition of the high melting point binder in the sintering process.

The present invention has been made in view of the above circumstances, and the degreasing and the sintering are performed in one furnace to shorten the steps, save energy, and reduce the cost. It is an object of the present invention to provide a vacuum degreasing and sintering furnace and a degreasing method using the same which can efficiently remove the binder of (1) and prevent a bad odor during sintering.

[0006]

To achieve the above object, in the vacuum degreasing and sintering furnace of the present invention, a furnace body and a material to be sintered, which is arranged in the furnace body and contains a binder, can be opened and closed freely. An exhaust pipe that is composed of a heating chamber and a degreasing device that is connected to the heating chamber and removes the binder to degrease it, and the degreasing device is connected to the heating chamber and discharges gas and liquid binder from the heating chamber. A collection device connected to the discharge pipe for collecting the liquid binder, a trap device connected to the collection device for collecting the gas binder, and a second pipe connected to the collection device for collecting the liquid binder. And a combustor connected to each other to combust a gas binder, and the first and second combustors.
And a switching valve provided on each of the pipes to open and close these pipes. Further, in the degreasing method of the present invention, the gas and liquid binder generated from the low melting point binder when the material to be sintered containing the binder placed in the heating chamber is heated is discharged through the discharge pipe, and the liquid binder is collected in the recovery device. The gas binder generated by the high melting point binder when the material to be sintered is heated to a higher temperature and then collected in the second pipe. It was led to the combustion device through and burned there.

[0007]

According to the vacuum degreasing and sintering furnace of the present invention and the degreasing method using the same, the first pipe is first opened by the on-off valve, and the material to be sintered containing the binder is heated to a low temperature range. At this time, the gas and liquid binder generated from the low melting point binder are discharged through a discharge pipe, the liquid binder is recovered by a recovery device, and further the gas binder is guided to a trap device and collected there. After that, the second pipe is opened by the on-off valve to heat the material to be sintered to a higher temperature region, and the gas binder generated from the high melting point binder at this time is guided to the combustion device and burned there.

[0008]

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

Reference numeral 1 in the drawing denotes a vacuum degreasing and sintering furnace of this embodiment. This vacuum degreasing and sintering furnace 1 is a vacuum degreasing and sintering furnace for MIM, and roughly includes a furnace body 2 and an openable / closable heating chamber 4 for sintering a sintered material 3 containing a binder and arranged in the furnace body 2. And a degreasing device 5 connected to the heating chamber 4 to remove the binder and degrease it.

The material to be sintered 3 is mixed with a material having a melting point lower than the sintering temperature, such as paraffin-based, polymer-based, oil-based or shape-retaining agent, for forming before sintering. Is mixed in.

The furnace body 2 includes a horizontally arranged cylindrical furnace body body 2a, a cooling fan device 2b provided at a ceiling portion for cooling the heating chamber 4, and side plates of the heating chamber provided at both sides (to be described later). ) 4c and the opening and closing drive device 2c for opening and closing.

The heating chamber 4 has an upper plate 4a fixed to the furnace body 2.
And a bottom plate 4b and side plates 4c that are horizontally movably attached to both sides of the furnace body 2. The heating chamber 4 is formed by combining these top plate 4a, bottom plate 4b and side plate 4c with each other. It has become so.
Inside the heating chamber 4, a column-shaped hearth 4d is installed horizontally on a bottom plate 4b, and a heater 4e is arranged on the entire inner peripheral surface so as to surround the hearth 4d.

The degreasing device 5 is roughly composed of a discharge pipe 6 connected to the heating chamber 4, a recovery device 7 connected to the discharge pipe 6, a trap device 8 and a combustion device 9 connected to the recovery device 7.
And is configured.

The discharge pipe 6 is for discharging the binder vaporized or liquefied in the heating chamber 4 from the heating chamber 4, and is inserted into the heating chamber 4 and attached to the bottom of the hearth 4d. .

The recovery device 7 is connected to the exhaust pipe 6 and connected to the furnace body 2.
The gas binder and the liquid binder that are installed below the heating chamber 4 and are discharged from the heating chamber 4 (the liquid binder is the one discharged from the heating chamber 4 and the one in which the gas binder is condensed and liquefied as the temperature decreases). It includes only the liquid binder of the above). Immediately below the exhaust pipe 6 inside the recovery device 7, a bucket 10 for storing the liquid binder is arranged.

The trap device 8 is a device which is connected to the recovery device 7 through a first pipe 11 and which collects and recovers the gaseous binder by condensing or coagulating it and converting it into a liquid or a solid. The trap device 8 is formed in a cylindrical shape, and is vertically provided upright from a bucket 12 for storing the liquid binder, which is provided below the trap device 8. Further, inside the trap device 8, a cooling water pipe 8a, fins 8b,
A first filter 8c is provided. Cooling water pipe 8a
Are arranged from the upper end to the lower part in the length direction of the trap device 8 and are formed so that the cooling water for cooling the gas binder can be supplied and drained in a circulating manner. Fin 8b
Is a member formed in the shape of an arc plate, and is provided in large numbers inside the central portion in the length direction of the trap device 8 with the curved inner surface facing downward. The first filter 8c is a fibrous member having a dust collecting action capable of capturing the binder, and is filled in the upper portion of the trap device 8.

The first pipe 11 is provided with a first opening / closing valve 13 for opening and closing the pipe 11.

The trap device 8 is connected to a final trap device 14 for condensing or solidifying the gas binder that could not be collected by the trap device 8 and converting it into a liquid or a solid to capture it. Final trap device 14
Is formed into a cylindrical shape, and the upper part of the inside is filled with the second filter 14a.

Further, on the upper part of the final trap device 14,
An exhaust device 15 such as a vacuum pump for sucking the binder from the heating chamber 4 is connected.

The combustion device 9 is connected to the recovery device 7 via the second pipe 16 and is a device for burning the gas binder. The combustion device 9 is a cylindrical container having an adiabatic wall that is a combustion chamber 9a whose interior is heated to a high temperature, and an exhaust port 9b for exhausting decomposed gas and the like generated by combustion to the outside is provided in the upper part. Has been. A burner 9c is arranged in the combustion chamber 9a as a heating means.

The second pipe 16 is provided with a second opening / closing valve 17 for opening and closing the pipe 16.

Next, a degreasing method using a vacuum degreasing sintering furnace will be described.

First, degreasing is performed in the vacuum degreasing and sintering furnace 1 having the above-mentioned structure. Sintered material 3 including binder is placed on hearth 4d
After being supported and stored in the heating chamber 4 and closing the side plate 4c, the inside of the heating chamber 4 is set to a predetermined temperature and pressure condition. The temperature is within a relatively low temperature range of about room temperature to 500 ° C., and the inert gas (carrier gas) is 1 to 5 Nl / min.
The pressure is reduced to about several Torr while flowing at a flow rate of about 10 Torr. In this state, the second on-off valve 17 is closed, the first on-off valve 13 is opened, and the exhaust device 15 is operated to operate the gas generated from the low melting point binder in the material 3 to be sintered in the heating chamber 4. Then, the liquid binder is sucked and discharged from the heating chamber 4 to the discharge pipe 6.

The gas and liquid binder are introduced into the recovery device 7 together with the carrier gas, and only the liquid binder is separated from the gas binder and recovered in the bucket 10. Further, the gas binder, which is condensed and liquefied as the temperature decreases, is also collected in the bucket 10.

The gas binder, together with the carrier gas,
It is guided to the trap device 8 via the first pipe 11.
The gas binder contacts the inner wall surface in the trap device 8, the wall surface of the cooling water pipe 8a and the fins 8b to condense and liquefy,
Lower bucket 1 as liquefied binder
It is stored in 2. Further, the solidified solid binder is caused to flow upward together with the carrier gas and is captured by the first filter 8c on the upper side.

The gas binder remaining in the carrier gas without being collected by the trap device 8 is the final trap device 1.
4 and is collected as a solid binder by the second filter 14a.

After the degreasing in the relatively low temperature region is completed as described above, the inside of the heating chamber 4 is continuously heated to a higher temperature region (5
The temperature is set to about 00 to 800 ° C., and an inert gas is flowed to return to normal pressure. In this state, the first on-off valve 13 is closed and the second on-off valve 17 is opened to degrease and sinter.

At this time, the gas binder generated from the high melting point binder in the material to be sintered 3 is guided to the combustion device 9 through the recovery device 7 and the second pipe 16, and is then introduced into the combustion chamber 9a. After combustion and decomposition, it is exhausted to the outside.

In the heating chamber 4, all the binder is removed and the remaining material to be sintered is sintered.

As described above, according to the vacuum degreasing and sintering furnace of this embodiment and the degreasing method using the same, the low melting point binder is first recovered by degreasing in a relatively low temperature range, and then in the high temperature range. By performing degreasing, the high-melting-point binder is burned and decomposed. Therefore, even if the binder is composed of a mixture of plural kinds of binders, all of them can be reliably and efficiently removed and degreased.

Since degreasing and sintering can be performed in one furnace, the process can be simplified and energy can be saved, and the equipment cost and running cost can be reduced.

Further, since the gas binder generated from the high melting point binder is combusted and decomposed in the combustor 9, the problem that the high melting point binder is decomposed to give off a bad odor during the sintering is avoided. You can also

The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0034]

As described above, according to the vacuum degreasing and sintering furnace and the degreasing method using the same according to the present invention, even if a binder composed of a mixture of a plurality of kinds of binders is used, all of them can be reliably performed. The degreasing can be performed efficiently and efficiently. Further, since degreasing and sintering can be performed in one furnace, it is possible to simplify the process, save energy, and reduce equipment cost and running cost. Further, it is possible to avoid the problem that the high melting point binder is decomposed in the heating chamber during sintering to give off a bad odor.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a vacuum degreasing and sintering furnace according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum degreasing sintering furnace 2 Furnace body 3 Sintered material 4 Heating chamber 5 Degreasing device 6 Discharge pipe 7 Recovery device 8 Trap device 9 Combustion device 11 First pipe 13 First opening / closing valve (opening / closing valve) 16 Second Piping 17 Second open / close valve (open / close valve)

Claims (2)

[Claims] 1. A furnace body, an openable and closable heating chamber arranged in the furnace chamber for sintering a material to be sintered containing a binder, and a degreasing device connected to the heating chamber for removing the binder to degrease the binder. A degreasing device connected to the heating chamber for discharging gas and liquid binder from the heating chamber; a recovery device connected to the exhaust pipe for recovering the liquid binder; and a first recovery device. A trap device for collecting the gas binder, a combustion device connected to the recovery device for connecting the gas binder and burning the gas binder, and the first and second pipes. A vacuum degreasing and sintering furnace, characterized in that it is provided with an on-off valve which is provided in each of the pipes to open and close these pipes. 2. A method of debinding and removing a binder using the vacuum degreasing and sintering furnace according to claim 1, wherein the material to be sintered containing the binder is heated in a heating chamber. The gas and liquid binder generated from the low melting point binder are discharged through the discharge pipe, the liquid binder is recovered by the recovery device, and the gas binder is guided to the trap device through the first pipe to be collected, and then the sintered body is sintered. A degreasing method, characterized in that a gas binder generated from a high melting point binder when the material is heated to a higher temperature is introduced into a combustion device through a second pipe and burned there.