JPH07173605A - Method and device for continuous pack cementation - Google Patents

Abstract

PURPOSE:To reduce a thickness variance of cemented film layer so as to shorten a treating time by continuously heating a non tight closure container filled with a cementing agent/objective metal part while passing a heating furnace and making an in-furnace temp. uniform, etc. CONSTITUTION:A non tight enclosure container 1 filled with a cementing agent/ objective metal part is transferred into an inlet side evacuating chamber 3, replacing the container inside with an inert gas etc. Sucessively, the container 1 is transferred to an external heating tubular heating chamber 54, subjecting to pack cemementation with elevating the container 1. Subsequently, the container 1 is transferred to a tubular cooling chamber 6, subjecting to forced cooling. Further, the container 1 is transferred to the delivery side evacuating chamber at the outlet side of the cooling chamber 6 and is carried out to outside atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for continuously treating a powder pack method in a diffusion infiltration treatment method for forming a diffusion coating layer such as chromium or aluminum on a metal surface of a steel part or the like.

[0002]

2. Description of the Related Art In the powder pack method, a metal powder (metal chrome, ferroaluminum, etc.) as a metal diffusion source and a halogen activator (usually NH ₄ Cl) are placed inside a heat resistant container 1b as shown in FIG. , A sintering treatment agent (for example, alumina powder) is buried and filled with a metal component to be subjected to diffusion permeation treatment, and this container is filled with a horizontal gas combustion furnace as shown in FIG. It is a batch-type method in which the container is charged into a heating furnace 5b, heated to and maintained at the permeation diffusion treatment temperature, and then allowed to cool outside the furnace together with the container.

Although not a powder pack method, a mixture of the diffusion treatment material and the metal parts to be treated is filled and settled from the upper end into an externally heated vertical reaction tube, and intermittently taken out from the lower end of the furnace. A method is known in which the time for diffusion and osmosis heating is secured, and as the amount of deposits in the reaction tube decreases, replenishment charging is performed from the upper part of the furnace (Japanese Patent Publication No. 63-56308).
issue).

[0004]

In the conventional powder pack method, it is necessary to completely seal the container by welding after filling the container so that the metal parts and the diffusion penetrant are not oxidized during heating. As shown in FIG. 7, in order to prevent the expansion and damage of the container 1b, a supply pipe 9b for sending an inert gas or a reducing gas to the container 1b and a degassing pipe 91b are connected, and during heating, Ar is supplied from the supply pipe 9b. Gas was supplied to prevent oxidation. Therefore, in the batch type powder pack method, it is necessary to weld and seal the container, and it is necessary to adjust the gas supply for each container. Further, the cooling after heating is carried out by taking it out of the furnace and allowing it to cool while the container is hermetically closed, so that the cooling time is long, and the work of fusing and cutting the container is required after cooling.

In addition, when the container is heated and held in a furnace, the heat-insulating material such as alumina causes a difference in the temperature rising rate depending on the filling position in the container, resulting in a temperature distribution.
There is a problem in that the thickness of the diffusion / permeation film varies from part to part.

The problem of the batch type powder pack method can be solved by the above continuous treatment method in which a reaction tube vertically passing through a vertical furnace is submerged in a mixture state and heated.
Excellent for large-scale processing of small-sized metal parts,
In this method, vaporized chloride is deposited during the reaction and adheres to a filler such as a diffusion penetrant to easily cause closed suspension inside the reaction tube, and the inner diameter of the reaction tube is increased to increase the throughput. If the value is increased, the temperature rise rate is reduced due to the heat insulating property of the diffusion penetrant, the residence time becomes longer, the processing capacity is limited, and it is not suitable for processing large parts. Was unsuitable.

The powder pack method has an advantage that one container is used as one unit, and the blending of the diffusion penetrant can be freely selected according to the type of metal parts. It was considered suitable. Therefore, the present invention intends to solve the problems of the batch type powder pack method and the continuous treatment method by providing a continuous treatment of the powder pack method, and to provide an apparatus therefor.

[0008]

A method for continuous diffusion and permeation treatment according to the present invention is a method in which a large number of unsealed or capped unsealed containers filled with a diffusion penetrant and a target metal part are sequentially loaded by a continuous transfer means. The first step of transferring to a vacuum deaeration chamber and replacing the inside of the container with an inert gas or a reducing gas, and the temperature of diffusion permeation treatment in an inert or reducing atmosphere by transferring to an external heating tubular heating chamber. In the inert or reducing atmosphere, carry out the second step of performing the diffusion and permeation treatment by raising the temperature and maintaining the temperature, and carrying it to the tubular cooling chamber having the wall wall forcibly water-cooled connected to the tubular heating chamber. It is characterized in that it comprises a third step of forcibly cooling with a pipe and a fourth step of transporting the container to an evacuating side vacuum deaeration chamber connected to the outlet side of the tubular cooling chamber and then carrying out the container to the outside air. It is a thing.

The continuous diffusion permeation treatment apparatus for realizing this treatment method has an external heating type tubular heating chamber and a tubular cooling chamber provided with a water cooling jacket between the vacuum degassing chambers on the loading side and the loading side. Connected to the heating chamber to supply an inert or reducing gas to control the atmosphere, and the cooling chamber is equipped with a gas cooler that circulates and cools the cooled pipe atmosphere gas. It is a continuous diffusion and infiltration treatment device in which a large number of unsealed containers with lids filled with metal parts are sequentially inserted through the heating chamber and the cooling chamber.

More specifically, the present apparatus is a continuous diffusion osmosis treatment apparatus for continuously heating and cooling a large number of unsealed or covered unsealed containers filled with a diffusion osmotic agent and target metal parts. A carrying-in side degassing unit having an air chamber, a heating unit in which a tubular heating chamber inside a heating tube inserted in a heating furnace is hermetically connected to the vacuum degassing chamber at its inlet side, and a water cooling jacket are provided. A tubular cooling chamber provided with a cooling unit whose inlet side is airtightly connected to the heating chamber, and an unloading side degassing unit having a gas replacement chamber airtightly connected to the outlet side of the cooling chamber, It comprises a conveyer unit provided between the carry-in side degassing unit and the carry-out side degassing unit for discharging and filling and transferring the container. Then, the vacuum degassing chamber, the tubular heating chamber, the tubular cooling chamber, and the gas replacement chamber, by the intermittent pushing means provided at least on the heating chamber inlet side and the cooling chamber outlet side, the container can be continuously conveyed. The heating pipe is connected with an introducing pipe for introducing an inert or reducing gas and an exhaust pipe for discharging atmospheric gas in the heating chamber through a pressure adjusting valve.

[0011]

The present invention is a continuous processing method of the powder pack method, in which a container filled with a diffusion penetrant and metal parts is filled into a horizontal heating tube inserted through a heating furnace from one end to the other end. While being transported, the container and its filling are heated to the diffusion permeation treatment temperature, and a permeation coating is formed on the surface of the metal component by the diffusion permeation action.

Since the inner tubular heating chamber is replaced with an inert gas or a reducing gas by using a heating tube and is shielded from external air and combustion gas, the container is opened without a lid or with a lid. In the case of a container, if the lid is placed on the container and not sealed, the chloride gas generated in the container escapes into the heating pipe.

The filler inside the container is heated uniformly while being conveyed in the long heating tube, and the variation of the coating thickness of the metal parts in one container is small. In addition, the variation in the film thickness between the containers is reduced.

The container moved to the cooling pipe connected to the heating pipe is rapidly cooled by the cooling pipe wall whose outer surface is water-cooled,
Compared to the case where the conventional completely sealed container is left to cool in the atmosphere,
Cooling time can be shortened.

In the continuous processing method, the number of processing vessels per unit time is determined by the time required for the heating process in the heating tube.
By increasing the cooling rate in the cooling step in the cooling tube, the cooling tube for the heating tube can be shortened, and the total number of containers in all steps can be reduced.

Atmosphere gas containing high-temperature moisture and gaseous chloride from the heating tube is mixed in the cooling tube, so that the cooling of the gas in the cooling tube is delayed, and chloride adheres to the wall of the tube for a long period of time. During operation, the gas flow rate in the cooling pipe decreases. The present invention cools the gas collected from the inlet side of the cooling pipe through the gas cooler by the gas cooler and returns it to the outlet side of the cooling pipe, thereby cooling the circulating gas in the cooling pipe, and then the container. Accelerate the cooling of.

The gas cooler cools the circulating gas to below the water vapor dew point and dehydrates it to reduce the partial pressure of water vapor in the diffusion and permeation atmosphere in the heating tube, thereby preventing oxidation of the penetrant due to water vapor. Since the gas cooler simultaneously solidifies the chloride gas by cooling and removes it as dust, it is possible to prevent the chloride gas from sticking in the cooling pipe and to keep the concentration of the chloride gas in the atmosphere of the cooling chamber and the heating chamber constant. It can be reduced to below the amount.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A continuous diffusion permeation treatment apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a horizontal sectional view of the present apparatus. In this apparatus, a rectangular container base 10 on which a container 1 is placed and fixed is provided from a preparation stand 2, a degassing section 3 on a loading side, and a heating front section. 4, heating section 5,
It is configured to move through a circulation path that returns to the preparation table 2 again via the cooling unit 6, the forced gas cooling unit 7, and the discharge side degassing unit 8. The heat-resistant container 1 is fixed on the container base 10, and on the preparation table 2, the filler after the treatment of the container 1 is discharged and a new filler is discharged during movement by a chain conveyor (not shown). It is loaded and transferred.

FIG. 3 is a cross-sectional view of the container 1 and the container base 10. The container base 10 is a rectangular heat-resistant steel thick plate, and the heat-resistant container 1 is fixed to the upper surface of the container 1, and the container 1 is fixed in the container 1 upward. The target metal part and the diffusion permeation treatment material are mixed and filled through the opening, and the upper lid 11 is simply placed on the opening.
Not sealed. Since the base 10 projects laterally around the peripheral edge of the container 1, even if the container bases 10 come into contact with each other during transport as will be described later, the containers 1 have a space therebetween. As it is formed (see FIG. 2), the tubular heating chamber 5
4 and the tubular cooling chamber 64 have good heat conduction into the container 1 and the containers 1 do not contact each other, so that the container is stable during transportation.

Referring to FIG. 1, the vacuum degassing chamber 34 of the carry-in side degassing section 3 first closes the front and rear vacuum valves 31 and 41 after the container base 10 is housed, and the vacuum pump 38 makes 100
The pressure is reduced to mmHg or less, and the inside of the filler in the container 1 is evacuated.
Then, Ar gas is introduced and replaced, the vacuum valve 41 is opened, and the gas is transferred to the pre-heating chamber 44.

The pre-heating chamber 44 is arranged linearly with the heating chamber 54 of the heating section 5, and the container 1 stands by until it is pushed into the heating chamber 54 by the hydraulic pusher 49. Is shielded.

In FIG. 2, the tubular heating chamber 54 of the heating section 5 is shown.
The container base 10 is linearly connected to the tubular cooling chamber 64 of the cooling unit 6 so that the container base 10 can be moved straight by the pushing force of the pusher 49, and a large number of container bases are provided in both chambers 54 and 64. 10
In this example, the peripheral side surfaces are substantially in contact with each other and form a line.

In the heating section 5, the heating chamber 54 is formed in the inner space 54 of the heat resistant heating pipe 53 penetrating the inner combustion chamber 52 of the heating furnace body 50 and is maintained at a high temperature. The new container 1 in the inlet side 541 of the heating pipe 53 is
While being heated up to about 0 to 950 ° C., it is gradually pushed and held at a required diffusion and penetration temperature for a desired time before reaching the outlet side 542, and a film is formed on the metal parts in the container 1 by the diffusion and penetration reaction. To be done.

A supply pipe 92 for supplying Ar gas or H ₂ -containing reducing gas is connected to the heating chamber 54 near its outlet side 542 to keep the heating chamber 54 in an inert or reducing atmosphere. Similarly, since the exhaust pipe 93 is connected to the outlet side 542 via the pressure regulating valve 931 and the container 1 is not sealed, moisture, metal chloride, ammonium chloride, hydrogen chloride, etc. generated by the temperature rise from the filling material However, pressure control is performed in order to prevent the heating chamber 54 from having a high pressure due to this gas.

Therefore, since the heating chamber 54 has an inert or reducing diffusion permeation atmosphere, the penetrant and the metal parts in the container 1 are not subject to oxidation. The lid is open.

FIG. 4 shows the container 1 in a cross section of the heating chamber 54. The combustion chamber 52 heated by the gas burner 528 heats the filling 13 in the container 1, but the cross section of the container 13 is approximately four. In the process of moving in the long heating tube 53, the packing 13 is heated uniformly with a small temperature gradient, and the temperature difference between the containers 1 forming a row is small.

In the next cooling unit 6, the water cooling chamber 60 is fixed to the outer wall of the tubular cooling pipe 63 to rapidly cool the gas in the cooling chamber 64. The water cooling chamber 60 is divided into three parts in the axial direction of the cooling pipe 63, and each of the chambers 60a, 60b, 60
Water is forcibly supplied to c by a water supply pipe 621 and a drain pipe 622, respectively, to enhance the cooling capacity.

Further, the cooling pipe 63 has an inlet side 641.
Is connected to the return pipe 99 connected to the outlet side 642 of the cooling pipe 63 via the gas cooler 97 and the blower 98 to circulate and cool the atmospheric gas in the cooling chamber 64. It The gas cooler 97 may be a water-cooled heat exchanger, is capable of collecting dust, is provided with a drain for drainage (not shown), and the inlet side temperature of the cooling chamber 64 is 300 to 300.
The atmospheric gas at 600 ° C. is cooled to about 50 to 70 ° C. at the outlet of the gas cooler 97. In the gas cooler 97, metal chloride in the atmospheric gas, for example, chromium chloride vapor, is solidified and removed in the gas cooler and simultaneously dehydrated.

The forced gas cooling chamber 74 includes the front and rear shutoff valves 7.
1, 1 and 81 are closed, and a non-oxidizing gas, usually nitrogen gas, is forcedly circulated by a blower 78 to cool it to near room temperature. Since the temperature is sufficiently low, nitrogen gas does not react with the penetrant / metal parts.

The vacuum deaeration chamber 84 on the discharge side is provided to isolate the atmosphere of the cooling chamber 64 and the heating chamber 54 from the outside air, like the vacuum deaeration chamber 34 on the inlet side.

As described above, since the infiltration treatment of the internal filler of the container which has passed through the apparatus has been completed, the fillers are sequentially replaced and circulated again in the apparatus.

In the steps from the carrying-in to the carry-in side degassing section 3 to the diffusion and permeation treatment and the discharging from the discharge side degassing section 8, the container base 10 is moved to the chambers 34, 34 by the pushers 49, 69, 89.
Slide on the bottom of 44, 54, 64, 74, 84,
A progressive feed system is adopted, but as shown in FIG.
The container base 10 may slide / roll on rails 532, 532 provided at the bottom of the rail, or preferably on a large number of cylindrical rollers (not shown) pivotally supported on the rail.

Next, a chromium diffusion and penetration test of the structural steel test piece was conducted by the method of the present invention.

The metal parts are JIS S45C steel with a length of 1
A round bar with a diameter of 0 mm and a diameter of 20 mm was used. The diffusion penetrant was 49% by weight of metal chromium powder, 50% by weight of alumina powder and 1% by weight of ammonium chloride.
It was filled in a rectangular container of 00 mm square, placed with an upper lid, and kept heated by this device.

The container is charged into the heating chamber at two levels of the heating furnace temperature of 900 ° C. and 950 ° C. The heating holding time was adjusted by setting the heating chamber length of about 10 m as the two levels of the tact time of 30 min and 45 min. The container having passed through the heating chamber was successively passed through a cooling unit having a length of 10 m to cool it to 200 ° C. or lower, and then cooled in a nitrogen stream. The temperature of the heating and cooling process was continuously measured by a thermocouple mounted in the container.

As a comparative example, a metal part and a diffusion penetrant having the same composition as in the above example were filled in a container having the same shape, and an upper lid was welded to the container opening for sealing. A on the side of the container
An r gas supply pipe and an exhaust pipe were attached.

For heating, a batch type electric furnace was used to charge the vessel and to flow an Ar stream while keeping the furnace temperature at 900 ° C. and 9 ° C.
The temperature was set to 50 ° C., and the temperature was kept at the same level for the same period as in the example. Then, it was taken out from the furnace in a red hot state and allowed to cool in the air.
The data of Examples and Comparative Examples are summarized in Table 1.

[0039]

[Table 1]

FIG. 5 shows the heating heat pattern (curve a) of the container in the example and the heat pattern (curve b) of the same shape container in the conventional batch type heating furnace according to the continuous method of the example. It can be seen that the cooling time of the cooling chamber is significantly shortened along with the heating time of the temperature rising process. Figure 6
Shows a flow chart of the diffusion and permeation treatment according to the example and the conventional method, but the method of the present invention shortens and reduces the work of filling the container with the penetrant and the work of taking it out from the container after cooling.
This is because the welding and sealing work and the fusing work of the conventional container can be omitted.

[0041]

According to the continuous diffusion and permeation method and apparatus of the present invention, since the atmosphere in the heating chamber and the cooling chamber in which the container is continuously conveyed can be controlled, the container filled with the penetrant and the metal parts. Does not require airtightness, enables uniform temperature inside the container by continuous heating, enables rapid cooling after permeation treatment, reduces variation in the thickness of the permeation coating layer, and shortens treatment time, improving workability and workability. It is effective for cost reduction, and the quality reliability is significantly improved.

Further, since the method and apparatus of the present invention perform continuous processing in container units, lot management is easy, and the mixing ratio is changed for each container while maintaining the same heating conditions in the heating chamber. Since it can use different penetrants and different kinds of metal sources, it is suitable for processing a wide variety of parts in small quantities.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of a continuous diffusion permeation treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view including a heating unit and a cooling unit of a continuous diffusion infiltration treatment device.

FIG. 3 is a perspective view of a container that stores a diffusion permeation treatment material.

FIG. 4 is a vertical cross-sectional view of a heating unit of a continuous diffusion infiltration treatment device.

FIG. 5 shows a heat pattern of a temperature inside a container during a continuous diffusion and infiltration treatment process.

FIG. 6 shows a time chart of conventional batch type (A) and continuous type (B) diffusion treatment steps of the present invention.

FIG. 7 is an external view of a conventional batch-type container.

FIG. 8 is a conceptual diagram showing an arrangement of a conventional batch-type heating furnace and a container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 container 10 container base 11 upper lid 2 preparation table 3 loading side degassing part 4 heating front part 43 heating front chamber 5 heating part 51 heating furnace body 52 combustion chamber 53 heating pipe 54 tubular heating chamber 6 cooling part 60 water cooling jacket 64 cooling Chamber 8 Degassing section on discharge side 97 Heat exchanger 98 Blower for circulation

Claims (7)

[Claims] 1. A large number of unsealed or covered unsealed containers filled with a diffusion penetrant and a target metal part are sequentially transferred to a vacuum deaeration chamber on the loading side by a continuous transfer means to inactivate the inside of the container. The first step of substituting the gas or reducing gas with the gas, and carrying it to the external heating type tubular heating chamber to raise the temperature to the diffusion permeation treatment temperature in an inert or reducing atmosphere and heat it to perform the diffusion permeation treatment 2 steps, a third step of carrying to a tubular cooling chamber having a pipe wall forcibly water-cooled connected to the tubular heating chamber, and forcibly cooling in an inert or reducing atmosphere, and the tubular cooling chamber A continuous diffusion and permeation treatment method for metal parts, which comprises a fourth step of transporting the container to the vacuum degassing chamber on the unloading side connected to the outlet side and then unloading the container to the open air. 2. In the second step, the atmosphere gas led out from the inlet side of the tubular cooling chamber is cooled to a dew point temperature or lower by a cooler, and then supplied to the outlet side of the tubular cooling chamber again to enter the cooling chamber. The continuous diffusion and infiltration treatment method according to claim 1, which is circulated. 3. A cooling replacement step for conveying and passing the container through a second tubular cooling chamber in which an inert gas or a reducing gas is forcedly circulated in the tube is provided between the third step and the fourth step. The continuous diffusion infiltration treatment method according to claim 1. 4. An external heating type tubular heating chamber and a tubular cooling chamber equipped with a water cooling jacket are directly connected between the vacuum deaeration chambers on the loading side and the loading side, and the heating chamber is inactive or reducing. The atmosphere is not controllable by supplying gas, and the cooling chamber is equipped with a gas cooler that circulates and cools the cooled atmosphere gas in the pipe. A continuous diffusion and infiltration treatment device that sequentially inserts the heating chamber and the cooling chamber. 5. A continuous diffusion infiltration treatment device for continuously heating and cooling a large number of unsealed or covered unsealed containers filled with a diffusion penetrant and a target metal part, the carry-in side having a vacuum degassing chamber. A degassing unit, a heating unit in which a tubular heating chamber inside a heating tube inserted in a heating furnace is airtightly connected to the vacuum degassing chamber at its inlet side, and a tubular cooling chamber having a water cooling jacket A cooling section having its inlet side airtightly connected to the heating chamber, an unloading side degassing section having a gas replacement chamber airtightly connected to the outlet side of the cooling chamber, and an inlet side deaeration Section and a conveyor section for discharging and filling and transferring the container provided between the discharge side degassing section, and the vacuum degassing chamber, the tubular heating chamber, the tubular cooling chamber, and the gas displacement chamber are at least heated. The container is continuously carried by the intermittent pushing means provided on the chamber inlet side and the cooling chamber outlet side. The heating pipe is connected to an inlet pipe for introducing an inert or reducing gas and an exhaust pipe for discharging atmospheric gas in the heating chamber through a pressure control valve. A characteristic continuous diffusion and infiltration treatment device for metal parts. 6. A gas cooler and a gas circulation blower are connected to the tubular cooling chamber between a suction pipe that sucks atmospheric gas at its inlet side and a return pipe connected to its outlet side. The continuous diffusion infiltration treatment device according to claim 5. 7. A second forcibly circulating an inert gas or a reducing gas in the pipe between the cooling unit and the degassing unit on the unloading side.
6. The continuous diffusion and infiltration treatment device according to claim 5, wherein the tubular cooling chamber is provided with a cooling displacement portion for conveying and passing the container.