JPH10204607A - Carburizing method for metallic material and carburizing treating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a setting place in which diffusion requires a treating time by several times as long as for carburizing and needing the length of a diffusing chamber and to solve the complication of its control by executing carburizing while a carrying material is carried as a longitudinal party in a row in the direction of the furnace length of a furnace in which carburizing and diffusing treatment are continuously treated under reduced pressure and thereafter moving it as longitudinal parties in plural rows. SOLUTION: A carrying material is charged from a carburizing chamber 13 to a diffusing chamber 14 as a longitudinal party in a row in the direction of the furnace length. In the diffusing chamber 14, the operation in which a primary material charged to the position of A is fed to B by a transverse beam and a secondary material is fed to A which have been made a vacant position is repeated. For example, 1st to 4th materials are divided into four rows to the positions of D to A on the upperst stream side. Next, these are advanced by that equivalent to a tray by a carrying roller 34, and the upperst stream side is vacated. On the vacated upperst stream side, 5 to 8th materials are divided into four rows similarly to the case of the 1st to 4th materials. This operation is repeated, the 1st to 4th materials divided into four rows are carried to the upperst stream side, and when they reach the positions of Z to W, the primary material at the Z position is exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for carburizing a metal material and a carburizing furnace. As a method of hardening the surface of the metal material, carburizing treatment such as vacuum carburizing or plasma carburizing is performed. In these carburizing treatments, a carburizing chamber in which a carburizing chamber is formed on the upstream side of the furnace and a diffusion chamber is formed on the downstream side of the furnace,
Carburizing is performed on the surface of the metal material in the carburizing chamber, and then carbon is diffused into the metal material in the diffusion chamber. The present invention relates to an improvement of such a carburizing method and a carburizing furnace.

[0002]

2. Description of the Related Art Conventionally, as a carburizing method as described above, a long carburizing furnace having a carburizing chamber formed upstream of a furnace and a diffusion chamber formed downstream of the furnace is used. While the metal material is transported in a single column in the furnace length direction, the surface of the metal material is carburized in a carburizing chamber, and then carbon is diffused into the metal material in a diffusion chamber. In the carburizing period in the carburizing chamber, the amount of carbon entering the surface of the metal material is affected by the flow of the carburizing gas, the arrangement of the metal material to be treated, and the like. In the furnace length direction
In the conventional method, even during the diffusion phase in the diffusion chamber, the carbon material is diffused while being transported as it is in a single column in the furnace length direction, even in the subsequent diffusion period in the diffusion chamber. .

[0003] However, the diffusion period takes several times longer than the carburization period. Therefore, when the metal material is carburized and carbon diffused while being conveyed in a single column in the furnace length direction as in the conventional method, the carbon material becomes extremely long. A long diffusion room is required. As the diffusion chamber becomes longer, not only does it require a longer installation area, but also the amount of heat dissipated from the diffusion chamber increases, and there are more related devices for controlling the temperature and atmosphere in the diffusion chamber. Therefore, the control becomes complicated.

[0004]

The problem to be solved by the present invention is that a conventional carburizing method and a conventional carburizing furnace are:
Carburizing and carbon diffusion while transporting the metal material in a single column in the furnace length direction requires a significantly longer diffusion chamber, thus requiring not only a longer installation site but also a greater diffusion. The amount of heat radiation from the room increases,
In addition, there are many related devices for controlling the temperature and atmosphere in the diffusion chamber, and the control becomes complicated.

[0005]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is directed to a carburizing treatment for continuously carburizing a metal material surface and diffusing carbon inside the metal material under reduced pressure.
The present invention relates to a method for carburizing a metal material, wherein the number of rows in the furnace length direction of the metal material is set to be greater in the diffusion period than in the carburization period. In the present invention, a carburizing chamber is formed on the upstream side of the furnace, and a diffusion chamber is formed on the downstream side of the furnace. The carburizing chamber is carburized in the carburizing chamber under reduced pressure, and then the metal material is formed in the diffusion chamber. In a carburizing furnace that diffuses carbon inside,
The diffusion chamber is equipped with a device for laterally feeding the metal material in the furnace width direction, and the device is configured such that the number of rows in the furnace length direction of the metal material in the diffusion chamber is larger than that in the carburizing chamber. The present invention relates to a carburizing furnace.

[0006] Also in the present invention, under reduced pressure, the surface of the metal material is carburized in the carburizing chamber, and then carbon is diffused into the metal material in the diffusion chamber. In the carburizing period in the carburizing chamber, carbon is introduced into the surface of the metal material in the presence of a carburizing gas under a predetermined temperature and a reduced pressure atmosphere, and further under a predetermined applied voltage in the case of plasma carburizing, and subsequently diffused. In the diffusion period in the room,
Carbon is diffused into the metal material at a predetermined temperature and reduced pressure in the absence of a carburizing gas.

In the present invention, the above-described carburizing treatment is performed such that the number of rows of metal materials conveyed in the furnace length direction is greater in the diffusion period than in the carburizing period. In the carburizing chamber, carburizing is carried out while transporting metal materials in a single column in the furnace length direction in principle.
In the subsequent diffusion chamber, carbon material is diffused while transporting the metal material in two or more columns in the furnace length direction. In this way, the diffusion chamber can be shortened by an amount corresponding to the increase in the number of rows in which the metal material is conveyed in the furnace length direction. Therefore, not only is the installation space required for the diffusion chamber short, but also the amount of heat radiation from the diffusion chamber. And the number of related devices for controlling the temperature and the atmosphere in the diffusion chamber is reduced, and the control is facilitated.

As described above, in the carburizing period in the carburizing chamber, the amount of carbon entering the surface of the metal material is affected by the flow of the carburizing gas and the arrangement of the metal material to be treated. In order to minimize the variation in the amount, the metal material is in principle arranged in a single column in the furnace length direction, preferably the metal material is moved in one line in the furnace length direction.
In the diffusion period in the diffusion chamber, the diffusion of carbon into the metal material is not affected by the arrangement of the metal material and is mainly controlled by the temperature. There is no problem even if it is transported by.

A carburizing chamber is formed on the upstream side of the furnace, and a diffusion chamber is formed on the downstream side of the furnace. Under reduced pressure, the surface of the metal material is carburized in the carburizing chamber, and then carbonized into the metal material in the diffusion chamber. In a carburizing furnace that diffuses, 1
In order to convert the metal material conveyed in the column into two or more columns in the furnace length direction in the diffusion chamber, the diffusion chamber is equipped with a device for laterally feeding the metal material in the furnace width direction. As such an apparatus, a pusher, a moving beam or the like can be used. For example, when a moving beam is used, the moving beam is provided at two positions between the conveying rollers supporting the metal material on the most downstream side and between the conveying rollers supporting the metal material on the most upstream side in the diffusion chamber. The moving beer itself rises → advances (advance in the furnace width direction)
A known device which repeats a substantially rectangular motion of → down → retreat (retreat in the furnace width direction) can be used.

[0010] When the metal material transported in a single column in the furnace length direction from the carburizing chamber is transported in four columns in the diffusion chamber, the metal materials are sequentially charged one by one from the carburizing chamber into the diffusion chamber.
Four rows of metal material charged at the uppermost stream side of the diffusion chamber → intermittent transport of four rows of metal material in the furnace length direction → metal material transported in four columns in the lowest position of the diffusion chamber Is repeated one by one. On the most downstream side of the diffusion chamber, four rows of metal materials are sequentially loaded one by one. For example, a cantilever roller that drives a transport roller supporting a metal material immediately before loading independently of other transport rollers. To

[0011]

1 is a cross-sectional view in the furnace length direction illustrating a carburizing furnace of the present invention, and FIG. 2 is a partially enlarged cross-sectional view in the furnace length direction showing the same carburizing furnace as FIG. . The illustrated carburizing furnace includes a purging chamber 11, a preheating chamber 12, a carburizing chamber 13, a diffusion chamber 14, and a quenching chamber 15 formed from the upstream side to the downstream side in the furnace. Purge chamber 1
1. Preheating chamber 12, carburizing chamber 13, diffusion chamber 14, and quenching chamber 1
5 is divided by opening / closing doors 21 to 26, and transport rollers 31 to 36 are laid in each of these chambers.
2. Carburizing chamber 13 and diffusion chamber 14 are made of heat insulating materials 41, 42, 4
It is surrounded by three. Although not shown, the purge chamber 1
1. Preheating chamber 12, carburizing chamber 13, diffusion chamber 14, and quenching chamber 1
5, a vacuum pump is connected through an opening / closing valve, a heating source is provided in the carburizing chamber 13 and the diffusion chamber 14, a cooling source is provided in the quenching chamber 15, and an opening / closing valve is provided in the carburizing chamber 13. The supply pipe and the discharge pipe of the carburizing gas are connected via the.

In the illustrated carburizing furnace, the metal material placed on the tray is transported in a single column in the carburizing chamber 13 in the furnace length direction, and is transported in a four-column column in the diffusion chamber 14 in the furnace length direction. It has become so. In order to sequentially separate the four rows of metal material from the carburizing chamber 13 in a single column in the furnace length direction in the diffusion chamber 14 and discharge the four rows of metal materials one by one from the diffusion chamber 14, the diffusion chamber is used. 14 is equipped with moving beams 51 and 52 as a device for laterally feeding the metal material, and a cantilever roller is used as the transport roller 35. The moving beam 51 is provided between the transport rollers 34 that support the most upstream metal material in the diffusion chamber 14, and the moving beam 52 is provided between the transport rollers 34 that support the most downstream metal material in the diffusion chamber 14. , 35, the transport roller 35 supports the metal material immediately before being discharged from the diffusion chamber 14, and is driven independently of the other transport rollers 34 in the diffusion chamber 35.

The first metal material transported in a single column in the furnace length direction is charged from the carburizing chamber 13 into the diffusion chamber 14 at the position of the metal material A. The first metal material charged is moved from the position of the metal material A to the position of the metal material B by the moving beam 51. Since the position of metal material A is empty,
The second metal material transported in a single column in the furnace length direction is transferred from the carburizing chamber 13 into the diffusion chamber 14 by the vacant metal material A.
To the position of. The moving beam 51 moves the first metal material from the position of the metal material B to the position of the metal material C, and moves the second metal material from the position of the metal material A to the metal material B.
Traverse to the position. Similarly, the first to fourth metal materials transported in a single column in the furnace length direction are supplied to the diffusion chamber 14.
Are arranged in four rows at the positions of the metal materials D to A on the uppermost stream side of the inside.

After the first to fourth metal materials are arranged in four rows at the most upstream side in the diffusion chamber 14, they are advanced by a distance corresponding to the tray by the transport roller 34, and the most upstream side is vacated. On the empty uppermost stream side, the fifth to eighth metal materials are divided into four rows in the same manner as described above. By repeating the above operation, 1
When the fourth to fourth metal materials are transported to the most downstream side in the diffusion chamber 14 and reach the positions of the metal materials Z to W, the first metal material at the position of the metal material Z is transported by the transport roller 35. It is loaded from the diffusion chamber 14 and the position of the metal material Z is opened. By the moving beam 52, 2 at the position of the metal material Y
The metal material at the position of metal material Z and metal material X
At the position of the metal material Y,
Further, after the fourth metal material at the position of the metal material W is laterally fed to the position of the metal material X, the second metal material laterally fed to the position of the metal material Z is transferred from the diffusion chamber 14 by the transport roller 35. After loading, the position of the metal material Z is vacated again. Similarly, the third and fourth metal materials are sequentially loaded from the diffusion chamber 14 and the lowermost downstream side in the diffusion chamber 14 is opened. The transport roller 34 transports the fifth to eighth metal materials to the vacant lowermost stream side.

The following is a repetition of the operation described above. Thus, the metal materials transported in the furnace length direction in a single column in the carburizing chamber 13 are charged one by one from the carburizing chamber 13 into the diffusion chamber 14, and the charged metal materials are stored in the diffusion chamber 14. After being divided into four rows and transported in four columns in the furnace length direction, they are loaded one by one from the diffusion chamber 14.

[0016]

As is apparent from the above description, according to the present invention as described above, the diffusion chamber can be shortened by the amount that the number of rows of metal materials conveyed in the furnace length direction in the diffusion period is larger than that in the carburization period. Therefore, not only the installation space required for the diffusion chamber is shortened, but also the amount of heat radiation from the diffusion chamber is reduced, and the related equipment for controlling the temperature and atmosphere in the diffusion chamber is reduced, and the control is also reduced. This has the effect of being easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the furnace length direction illustrating a carburizing furnace of the present invention.

FIG. 2 is a partially enlarged cross-sectional view in the furnace length direction showing the same carburizing furnace as in FIG.

[Explanation of symbols]

13 ... carburizing chamber, 14 ... diffusion chamber, 31-35 ...
.Conveying rollers, 51, 52... Moving beams

Claims (2)

[Claims] In a carburizing process for continuously carburizing a metal material surface and diffusing carbon inside the metal material under reduced pressure, the number of rows in the furnace length direction of the metal material is set to be smaller in the diffusion period than in the carburization period. A method for carburizing a metal material, characterized in that the amount of the carburizing treatment is increased. 2. A carburizing chamber is formed on the upstream side of the furnace and a diffusion chamber is formed on the downstream side of the furnace. The carburizing chamber is carburized in the carburizing chamber under reduced pressure, and then the metal material is formed in the diffusion chamber. In the carburizing furnace for diffusing carbon into the inside, a device for laterally feeding the metal material in the furnace width direction is provided in the diffusion chamber. A carburizing furnace characterized in that the number of the carburizing treatment is increased.