JP2003183724A - Heat treatment furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous vacuum carburizing furnace, which can continuously perform several carburization treatments, and can form a high concentration of carburized layer. <P>SOLUTION: This heat treatment furnace comprises arranging a suction port 126 for vacuum suction, a heater 116, and a gas supply port 120, in carburization treatment chambers 22 and 24 of the vacuum carburizing furnace 10; heating an article W to be treated which has been inserted into the carburization treatment chambers 22 and 24, with the heater 116 under vacuum, to react the article with gas; arranging the gas cooling chambers 26 and 28 underneath the carburization treatment chambers 22 and 24, and cooling the article W with gas, which has been taken out from the carburization treatment chambers 22 and 24 downward, to allow hardening after carburization to be simultaneously performed in a continuous flow. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat treatment furnace,
In particular, the present invention relates to a heat treatment furnace suitable for application to a continuous vacuum carburizing furnace.

[0002]

2. Description of the Related Art For example, a gear as a machine component is carburized at the outer peripheral portion where the tooth surface is formed to quench and temper it, thereby hardening the tooth surface. Conventionally, gas carburization has been generally performed as a method of carburizing treatment. In this gas carburizing, an object to be treated is placed in an atmosphere of gas for carburizing, and the gas is caused to act under heating to perform carburizing.

In the case of this gas carburization, the object to be treated is heated by heating the atmosphere, that is, the carburizing gas can be used as a heating medium for the object to be treated, and the object to be treated is relatively uniformly carburized. Is possible. However, in the case of gas carburization, CO ₂ is generated, which causes a problem of exhaust gas treatment, and since a large amount of gas is used, a large amount of heating energy is required and the economy is poor.

Therefore, recently, vacuum carburization, in which a gas is supplied to an object to be processed while heating in a vacuum to perform carburization, has attracted attention.

[0005]

In the case of this vacuum carburizing treatment, while the above problems in gas carburizing can be avoided, there is a problem that carburizing unevenness easily occurs as a unique problem. One of the reasons is that the temperature of the object to be processed does not become uniform in each part under the radiant heating by the heater, that is, temperature unevenness occurs, and the other one is supplied from the gas supply port. The gas concentration is not uniform in each part of the object to be treated, that is, the gas concentration is uneven.

Whether the above-mentioned gas carburizing or vacuum carburizing is used, these carburizing treatments infiltrate C into the surface of the object to be treated. Is difficult to do. For example, the carbon concentration of the initial surface of the carburized material (workpiece) is 0.15 to 0.
If it is about 2%, the C concentration on the surface that can usually be reached by one carburizing treatment is about 0.7 to 0.8%. Further, it is known that in order to increase the C concentration on the surface of the object to be treated and further increase the hardness, the carburizing treatment should be performed again after the quenching.

By the way, as a quenching method, oil quenching has heretofore been widely performed. In the case of oil quenching, the object to be treated can be rapidly cooled and the surface hardness can be effectively increased. On the other hand, however, in the case of this oil quenching, once oil quenching is performed, there is a problem that the subsequent processing is difficult. After the oil quenching, the oil drips from the surface of the object to be treated, causing an environmental problem, and since the oil adheres to the surface of the object to be treated, the subsequent carburizing treatment cannot proceed.

[0008] Therefore, when performing such oil quenching, there is a problem in that successive carburizing furnaces cannot be used for successive treatments, and at the same time, a plurality of carburizing treatments cannot be performed continuously. That is, in the past, a continuous carburizing furnace capable of carrying out carburizing treatment a plurality of times repeatedly has not been realized until the object is carried in from the carry-in port and carried out from the carry-out port. It is the actual situation.

Although the case of carburizing has been described above as an example, a common problem may occur when performing a series of heat treatments in which a heat treatment is performed in a heating chamber while supplying a gas, then cooled and then repeated.

[0010]

The heat treatment furnace of the present invention has been devised to solve such a problem. Thus, in the first aspect, the heater and the gas supply port are provided in the heating chamber, and the gas to be heated by the heater and acted on the object to be processed is inserted into the heating chamber. In the heat treatment furnace that can be supplied from the gas supply port,
A gas cooling chamber is provided below the heating chamber so that the object to be treated taken out downward from the heating chamber can be cooled with gas.

A second aspect of the present invention is the chamber according to the first aspect, wherein the heating chamber heat-treats the object to be treated in a decompressed state, and the object to be treated is provided between the heating chamber and the gas cooling chamber. A door is provided for loading and unloading the processed material up and down, and an airtight door for opening and closing the door is provided, and the gas cooling chamber is configured to be an airtight chamber when the airtight door is closed. It is characterized by being.

According to a third aspect of the present invention, in the second aspect, the heating chamber is accommodated in an accommodation chamber above the gas cooling chamber, and the lower wall of the heating chamber, the accommodation chamber and the gas cooling chamber. The entrance and exit are provided in the partition wall and the entrance and exit of the lower wall is also provided with a door that also serves as a heat shielding material, and the entrance and exit of the partition wall is provided with the airtight door, It is characterized in that a double door structure is provided between the chamber and the gas cooling chamber.

According to a fourth aspect of the present invention, in any one of the first to third aspects, at least two heat treatment units each including the heating chamber and the lower gas cooling chamber are provided in series. .

A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the heat treatment section in units of the heating chamber and the gas cooling chamber is a carburizing section.

[0015]

As described above, in the heat treatment furnace according to the first aspect, the heating chamber is provided on the upper side and the gas cooling chamber is provided on the lower side. In this heat treatment furnace, for example, after carburizing the object to be treated in the heating chamber, this is taken out into the gas cooling chamber on the After being taken out to the gas cooling chamber, the gas cooling, that is, the quenching treatment can be immediately performed. That is, in the heat treatment unit in which the heating chamber and the lower gas cooling chamber are used as a unit, for example, carburizing treatment and subsequent quenching treatment can be performed together.

Therefore, by providing this heat treatment unit in two or more units in one heat treatment furnace, it is possible to successively perform carburization and quenching on the object to be treated (Claim 4). It becomes possible to continuously perform high-concentration carburization on the processed material. Further, in the case of the heat treatment furnace of claim 1, since gas cooling is used as a cooling method, the above problems in oil cooling do not occur, and the object to be processed after cooling is successively subjected to the next carburizing process. There is an advantage that can be.

In the present invention, the heating chamber is depressurized,
For example, heating and gas supply to the object to be processed in a vacuum state, for example, vacuum carburization processing can be performed in a heating chamber. In this case, according to claim 2,
An inlet / outlet for vertically moving the object to be processed may be provided between the heating chamber and the gas cooling chamber, and the inlet / outlet may be sealed with an airtight door, and the lower gas cooling chamber may be configured as an airtight cooling chamber. it can.

In this case, after inserting the object to be processed from the inlet of the gas cooling chamber, the gas cooling chamber once in the atmospheric pressure state is evacuated to a vacuum state, after which the lower side The gas cooling chamber and the upper heating chamber can be brought into a state in which the airtight door is opened to communicate with each other, and the object to be processed can be subsequently inserted into the heating chamber. For example, if a carbon material with high heat resistance and high heat insulation is used for the walls that make up the heating chamber, the air inside the gas cooling chamber will enter the heating chamber if the opening / closing door is opened with air in the lower gas cooling chamber. Therefore, the carbon material burns there.

However, in the case of the heat treatment furnace of claim 2,
There is an advantage that the object to be treated can be inserted into the heating chamber through the inlet / outlet in a vacuum state except the air in the gas cooling chamber, and the above-mentioned inconvenience does not occur.

According to a third aspect of the present invention, the heating chamber is housed in a housing chamber above the gas cooling chamber, and a door is provided in a lower wall of the heating chamber and a wall separating the housing chamber and the gas cooling chamber. The door of the lower wall also serves as a heat shield material, and the door of the partition wall is equipped with an airtight door. While it is possible to prevent heat from escaping from the heating chamber, the gas cooling chamber can be made airtight by the airtight door provided at the entrance of the partition wall,
Each can be assigned a role.

Therefore, as compared with the case where only the airtight door is provided, the double door structure as described above does not require the airtight door of the heating chamber to have a heat shielding function, and the airtight door is heat resistant. It is possible to obtain an advantage that the material does not have to be a heat-shielding material. Here, the gas cooling chamber on the lower side of the heating chamber can be configured to also serve as a transfer space for the object to be processed.

In the present invention, in particular, the carburizing treatment and the quenching treatment are performed on the object to be treated by the heating chamber and the gas cooling chamber, that is, the heat treatment unit including the heating chamber and the gas cooling chamber is carburized. It can be configured as a processing unit (claim 5).

[0023]

Embodiments of the present invention applied to a continuous vacuum carburizing furnace will be described in detail with reference to the drawings. In FIG. 1, reference numeral 10 denotes a continuous vacuum carburizing furnace as a heat treatment furnace, which has a temperature soaking part 12, a first carburizing part 14, and a second carburizing part 16 from left to right in the figure. Each of the temperature raising and soaking unit 12, the first carburizing unit 14, and the second carburizing unit 16 has a metal furnace body 18.

In the temperature raising and soaking unit 12, the furnace body 18
A temperature rising and soaking chamber 20 is provided inside, and the first
In the carburizing unit 14 and the second carburizing unit 16, carburizing chambers (heating chambers) 22 and 24 are provided inside the furnace body 18. The internal structure of the temperature rising and soaking chamber 20 is basically the same as that of the carburizing chamber 22 as described later.

In the first carburizing unit 14 and the second carburizing unit 16, below the carburizing chambers 22 and 24, gas cooling chambers 26 and 28, which also function as transfer chambers, are formed, respectively, and the temperature rising and soaking is performed. In the section 12, a purge chamber 30 which doubles as a transfer chamber is formed below the temperature rising and soaking chamber 20. Here, the purge chamber 30 is for opening the carry-in port 32 and carrying in the object to be treated W, and then discharging the internal air to make the same vacuum state as the gas cooling chamber 26 of the first carburizing unit 14. is there.
The gas cooling chamber 28 in the second carburizing section 16 also serves as a purge chamber.

The purge chamber 30 has the carry-in port 32 and the outlet 34, which are opened and closed by doors 36 and 38, respectively. Here, the door 36 on the carry-in entrance 32 side
Is opened and closed by an opening and closing device 40, and the door 38 of the outlet 34 is opened and closed by an opening and closing device 42. These switchgear 40,4
2 has drive cylinders 44 and 46, respectively,
The door 3 is extended and retracted by the drive cylinders 44 and 46.
6, 38 are opened and closed.

Next, the gas cooling chamber 2 in the first carburizing section 14
6 is an inlet 48, an outlet 50 and doors 52, 5 for opening and closing them.
Have four. The door 52 on the entrance 48 side can be opened and closed by the opening / closing device 42 common to the door 38, and the door 5 on the exit 50 side.
4 is opened / closed by another opening / closing device 56. The opening / closing device 56 also has a drive cylinder 46, and the door 54 is opened / closed by the expansion / contraction operation of the drive cylinder 46.

The gas cooling chamber 28 of the second carburizing section 16 following the first carburizing section 14 also has an inlet 58 and an outlet 60, which can be opened and closed by doors 62 and 64. There is. Here, the door 62 on the inlet 58 side is the gas cooling chamber 2
It is opened and closed by the opening and closing device 56 common to the door 54 of 6,
Further, the door 64 of the carry-out port 60 is opened / closed by another opening / closing device 66. This opening / closing device 66 is also the drive cylinder 6
8, and the door 64 is opened and closed by the expansion and contraction operation.

Inside the purge chamber 30 and the gas cooling chambers 26 and 28, there is provided a carrying roller 70 for carrying the object W to be processed.
The workpiece W is sequentially conveyed from the temperature raising and soaking unit 12 to the first carburizing unit 14 and further to the second carburizing unit 16.

On the left side of the temperature-increasing and soaking unit 12 in the drawing, a transfer table 74 having a transfer roller 72 on the upper surface is installed, and also on the right side of the second carburizing unit 16 in the drawing, the same. A dolly 76 having a transport roller 72 on the upper surface is arranged. In this vacuum carburizing furnace 10, the workpiece W on the carrier table 74 is processed.
Is first carried into the temperature raising and soaking unit 12 through the carry-in port 32, then carried into the first carburizing unit 14, and then carried into the next second carburizing unit 16, and then from the carry-out port 60 to the outside. It is carried out and moved to the next process by the carriage 76.

4 and 5 specifically show the structure of the inside and the peripheral portion of the carburizing chamber 22 in the first carburizing section 14. In these figures, the carburizing chamber 22 is the storage chamber 7
It is housed in 7. Reference numeral 78 denotes a heat-resistant and heat-insulating wall (made of carbon) in the carburizing chamber 22, which has an upper wall 78A, a lower wall 78B, and a side peripheral wall 78C, and has a rectangular box shape as a whole.

The lower wall 78B is provided with a vertical entrance / exit 80, and the entrance / exit 80 is opened and closed by a heat-resistant and heat-insulating door (made of carbon) 82. Here, the door 82 forms a part of the lower wall 78B. The door 82 shields radiant heat from a heater 116, which will be described later, keeps the inside of the carburizing chamber 22 at a high temperature, and prevents the heat inside from escaping downward.

This door 82 is divided into a pair of halves (see FIG. 7) 82A, 82A which can be opened and closed in the left-right direction in FIG. 4, each of which is provided by a pair of opening / closing devices 84 shown in FIG. It can be opened and closed horizontally.
Here, the opening / closing device 84 has a drive cylinder 85,
And on the piston rod 87 of the drive cylinder 85,
The halves 82A and 82A are connected to each other. As shown in FIG. 7, each of the half bodies 82A has a semi-circular recessed portion 86 in the center thereof, and when the door 82 is closed, the recessed portions 86 have a slight amount in a lift rod 100 to be described later. They fit together with a gap.

In FIG. 4, reference numeral 88 denotes a partition wall provided in the first carburizing portion 14, which has an entrance / exit 90, and FIG.
The entrance 90 is opened and closed by an airtight door 92 as shown in FIG. That is, in this example, a double door structure is provided between the inside of the carburizing chamber 22 and the lower cooling chamber 26.

Here, the gas cooling chamber 26 below the carburizing chamber 22 in the first carburizing section 14 becomes an airtight chamber when the airtight door 92 is closed and the front and rear doors 52 and 54 are closed. It is configured.

In FIG. 5, reference numeral 94 denotes an opening / closing device for opening / closing the airtight door 92, which has a drive cylinder 96. The operation of the drive cylinder 96 and the rotation of the parallel link 98 open / close the airtight door 92. To be made.

In FIG. 4, reference numeral 100 denotes an elevating rod, and the workpiece W on the conveying roller 70 is the elevating rod 100.
By the ascending movement of the tray 104, the tray 104 is placed on the upper surface of the large-diameter base portion 102 at the upper end thereof, passes through the entrance / exit 90 of the partition wall 88, and is carburized from the entrance / exit 80 of the lower wall 78B of the carburizing chamber 22. It is inserted into the processing chamber 22. In this example, the workpiece W is a gear (see FIG. 8) as a mechanical component, and the tray 104 is provided with a holding rod 106 which fits the gear W and holds the tray 104 in a stacked state.

The elevating rod 100 has an upper portion 100A which is inserted into the carburizing chamber 22 as shown in FIG.
And a lower portion 100B below the lower portion 100B, which are made of different materials. That is, the upper part 100A is made of a heat resistant material, and the lower part 100B is made of a metal material.
Here, the metal lower part 100B has a water cooling structure.

As shown in FIGS. 1 and 3, the elevating rod 100 penetrates the seal member 108, and the elevating slider 110 is connected to the lower end portion thereof. The elevating slider 110 has a female screw portion 112, and the female screw portion 112 is screwed onto a male screw shaft 114. The elevating slider 110 is raised and lowered by the rotational movement of the male screw shaft 114, whereby the elevating rod 100 is moved. It can be moved up and down.

As shown in FIGS. 2 and 6, a heater 116 is disposed inside the carburizing chamber 22 along the inner surface of the side peripheral wall 78C so as to substantially surround the workpiece W. ing. Here, the heater 116 is divided into three upper and lower portions 116A, 116B, and 116C in FIG. As the heater 116, any heater such as an electric heater or a radiant tube heater can be used.

Further, inside the heater 116, a gas supply pipe 118 is provided along the inner surface of the side peripheral wall 78C so as to surround the object W to be treated.
The plurality of gas supply pipes 118 are provided with a plurality of ejection ports, which form a gas supply port 120 for supplying a gas for carburizing methane, ethane, propane or the like.

In FIG. 4, reference numeral 122 denotes a suction pipe which penetrates the upper wall 78A of the carburizing chamber 22 and enters the inside thereof, and the tip portion of which is a space formed at the center of the object W to be treated. Has been inserted into the section. And suction pipe 1
A large number of openings 124 are provided at the tip of 22.
The suction port 126 is constituted by them. The suction pipe 122 is the connecting pipe 1 as shown in FIG.
It is connected via a vacuum suction device (not shown) via 28.

As shown in FIG. 5, the first carburized portion 14
Has a plasma generator 130. The plasma generator 130 includes a plasma power source 132 and a pair of electrodes 13.
4, 136, and one electrode 136 has
A cylinder 138 is capable of advancing and retracting in the left-right direction in the drawing. The electrode 136 is in a state of retreating in the left-right direction in the figure when the lifting rod 100 places the workpiece W thereon and ascends and descends, and when the lifting rod 100 reaches the rising end, it moves forward by the cylinder 138, The electrode 136 contacts the base 102 at the upper end of the elevating rod 100.

In this plasma generator 130,
One positive electrode 134 is brought into contact with the wall 78 in the carburizing chamber 22, and the negative electrode 136 is brought into contact with the workpiece W through the base 102, and a voltage is applied between them to carry out the carburizing treatment. The gas supplied into the chamber 22 is turned into plasma.

In FIG. 3, 140 is a gas cooling device, which is connected to the gas cooling chamber 26 of the first carburizing unit 14 via ducts 142 and 144. This gas cooling device 140 is
It has a motor 146, a fan 148, and a heat exchanger 150, and circulates a cooling gas through the heat exchanger 150 in the direction of the arrow in the drawing, whereby the inside of the gas cooling chamber 26, specifically, the cooling chamber. The object W in 26 is forcibly cooled. The structure of the second carburized portion 16 is basically the same as that of the first carburized portion 1.
4 and is similar to the gas cooling chamber 2 shown in FIG.
It is the same as the first carburizing unit 14 in that the gas cooling device 140 for cooling 8 is provided.

On the other hand, the internal structure of the temperature raising and soaking unit 12 is also the first
This is the same as the carburizing unit 14, but the temperature soaking unit 12 is not provided with the gas cooling device 140 as shown in FIG. However, it is also possible to connect such a gas cooling device 140 to the lower purge chamber 30 and configure the purge chamber 30 as a gas cooling chamber.

Next, the operation of this equipment will be described with reference to FIGS. First, the workpiece W is carried into the purge chamber 30 in the temperature raising and temperature equalizing unit 12 as the first processing unit through the carry-in port 32, and when the purge chamber 30 is vacuumed, it is in the closed state shown in FIG. The airtight door 92 is opened as shown in FIG. Subsequently, the raising and lowering rod 100 moves upward due to the rotational movement of the male screw shaft 114, and the object W to be processed on the conveying roller 70 is received by the upper surface of the base 102 and lifted.

Then, as shown in FIG. 11, this is inserted into the temperature rising and soaking chamber 20. After that, as shown in FIG. 12, the half-shaped door 82 is closed.

In this state, the object W to be processed is heated by radiant heat from the heater 116 for a predetermined time, heated to a target temperature, and then held in that temperature-raised state for soaking. After that, the half-split door 82 is opened again to the state shown in FIG. 10, and the workpiece W is again lowered into the lower purge chamber 30. Subsequently, the workpiece W is sent to the gas cooling chamber 26 of the next first carburizing unit (second treating unit) 14 by the rotation of the conveying roller 70 after the opening operation of the doors 38 and 52 in FIG. 10 and 11 are inserted into the carburizing chamber 22 of the first carburizing unit 14 in the order shown in FIGS.

At the same time as the object W to be processed is carried into the gas cooling chamber 26 of the first carburizing section 14 from the purge chamber 30 of the temperature soaking / heating section 12, a new object W to be processed is heated in the temperature soaking / uniforming section 12. When it is inserted into the purge chamber 30, air also enters the gas cooling chamber 26. At that time, by keeping the airtight door 92 in a closed state, it is possible to prevent the air in the gas cooling chamber 26 from entering the inside of the carburizing chamber 22.

When the object W is carried into the gas cooling chamber 26, the inside of the cooling chamber 26 can be brought to a vacuum state by closing the door 52 and exhausting the cooling chamber 26. The airtight door 92 can then be opened.

Then, the object W to be processed is carburized in the carburizing chamber 2.
The second half split door 82 inserted in the second chamber is closed, and the action of the gas supplied from the gas supply port 120 and the heater 116 are closed.
The object W to be processed is carburized in a vacuum state by the radiant heat generated by.

The object W to be treated is subjected to the above-mentioned carburizing treatment in the carburizing treatment chamber 22 for a predetermined time, and then lowered to the lower gas cooling chamber 26 by the descending motion of the elevating rod 100.

In the first carburizing section 14, plasma carburizing can be performed. That is, the wall 78 of the processing chamber 22 is used as an anode and the object to be processed W is used as a cathode, and a predetermined voltage is applied between them to turn the internal gas into plasma, and the ions of the carburizing gas are forced to the object to be processed W. The carburizing process can be performed by colliding well.

The object W that has been lowered into the gas cooling chamber 26 is rapidly cooled in the gas cooling chamber 26 by the gas cooling device 140, and the temperature thereof is lowered to a predetermined temperature. That is, here, the first quenching is performed on the object W by gas cooling.

The object to be treated W which has been subjected to the first carburizing treatment in the first carburizing unit 14 is subsequently sent to the second carburizing unit (third treating unit) 16 where the second carburizing process is performed. Is carburized. The procedure of the carburizing process in the second carburizing section 16 is basically the same as that in the first carburizing section. Thus, by carburizing the object W to be processed in two stages in this manner, the carbon concentration on the surface of the object W can be increased. Moreover, in the equipment of this example, this two-step carburizing treatment can be performed while continuously flowing the workpiece W.

In the above, the temperature soaking and soaking unit 12 as the first processing unit performs the temperature soaking and soaking process, the first carburizing unit 14 performs the first carburizing process, and the second carburizing unit 16 performs the first carburizing process. Although it has been described that the second stage carburizing process is performed, in some cases, the temperature raising and soaking unit 12 performs the temperature raising and soaking process and the plasma carburizing,
It is also possible to perform pulse carburizing or vacuum carburizing in which the carburizing gas is intermittently injected in the first carburizing unit 14, and then further carburize in the second carburizing unit 16. In this case, the temperature raising and soaking unit 12 also serves as a carburizing treatment unit, and the temperature raising and soaking chamber 20 as the processing chamber thereof also functions as a carburization treatment chamber.

In the above example, the order of the treatments for the same workpiece W is mainly described, but for the workpieces W that are normally conveyed one after another, the temperature raising and soaking unit 12, the first carburizing unit are used. 1
4, in the second carburizing unit 16, each processing chamber 20, 22, 24
The objects W to be processed are accommodated therein, and the respective processes are simultaneously performed in parallel. In this case, as described above, the cooling chamber 26 in the first carburizing unit 14 can be made to function as a purge chamber.

In the above example, the gas cooling device 140 is installed separately from the gas cooling chambers 26 and 28, and the gas cooling device 140 and the gas cooling chambers 26 and 28 are connected to the ducts 142 and
Although connected via 144, as shown in FIG. 14, the gas cooling chambers 26 and 28 are directly provided with the gas cooling device 140, and the gas cooling device 140 allows the gas cooling chamber 2 to operate.
It is also possible to circulate the cooling gas through the heat exchanger 150 in the inside of 6, 28 and to perform forced gas cooling of the object W to be processed.

In the vacuum carburizing furnace 10 of the present embodiment configured as described above, the carburizing chambers 22, 2 for the workpiece W are
After carrying out carburizing treatment in No. 4, this is put in the lower gas cooling chamber 2
After taking out to No. 6, 28, gas cooling, that is, quenching treatment can be immediately performed. That is, in the vacuum carburizing furnace 10, both the carburizing treatment and the subsequent quenching treatment can be performed.

Further, in the present example, the vacuum carburizing furnace 10 is provided with the first carburizing section 14 and the second carburizing section 16 in series, that is, the carburizing section including the carburizing chamber and the gas cooling chamber as a unit. 2
Since it is provided in series, the vacuum carburizing furnace 10 for the workpiece W
The carburization and quenching treatment can be performed twice only by passing through, and the high-concentration carburization can be continuously performed on the workpiece W.

Further, in this example, since gas cooling is used as the cooling method, the problem as in oil cooling does not occur, and the object once hardened can be continuously supplied to the next carburizing section.

Further, in this embodiment, the cooling chambers 26 and 28 in the first carburizing unit 14 and the second carburizing unit 16 are configured to be airtight chambers, so that the cooling chambers 26 and 28 are once brought to the atmospheric pressure state. However, it is possible to prevent the air inside the cooling chambers 26 and 28 from entering the upper carburizing chambers 22 and 24, which allows the workpiece W to be successively introduced from the carry-in port 36 into the vacuum carburizing furnace 10. In the respective processing chambers, the workpiece W can be simultaneously subjected to the temperature-increasing soaking treatment, the first-stage carburizing treatment, and the second-stage carburizing treatment while being fed into the chamber.

Further, in this example, the temperature raising and soaking chamber 20, the carburizing chambers 22 and 24, and the purge chamber 30 and cooling chamber 2 below them are provided.
Since the double door structure is provided between the purging chamber 30 and the cooling chambers 26 and 28, the door 82 of the entrance / exit 80 of the lower wall 78b of each processing chamber is configured as a heat shielding door. The airtight door 92 for making the airtight state need not have a heat shielding function, and there is an advantage that the airtight door 92 does not have to be a heat resistant and heat shielding material.

The embodiment of the present invention has been described in detail above, but this is merely an example. For example, in the above embodiment, while the gas supply port 120 is used as the suction port, the suction port 12
6 is used as a gas supply port, the carburizing gas ejected from the central portion is passed through the workpiece W, and the suction port 126 on the outer peripheral side is provided.
Alternatively, the functions of the gas supply port 120 and the suction port 126 may be alternately switched so as to alternately switch the gas flow.

Further, in the above example, the heater 116 and the gas supply port 120 are provided only at the position on the outer peripheral side that surrounds the object W to be processed. However, depending on the case, the objects to be inserted into the respective processing chambers 20, 22, 24 may be changed. It is also possible to dispose the heaters 116 above the workpiece W or above and below the workpiece W to heat the workpiece W.

Furthermore, it is also possible to provide a gas supply passage or a suction passage so as to pass through the inside of the elevating rod 100 and to supply gas or perform vacuum suction through them. Although the above example is an example of a continuous type vacuum carburizing furnace, the present invention can also be applied to a batch type vacuum carburizing furnace, or a nitriding heat treatment furnace or a sintering treatment furnace other than the carburizing treatment furnace. For example, the present invention can be applied to a heat treatment furnace for other purposes, and the present invention can be configured in a form in which various changes are made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view showing the overall configuration of a continuous type vacuum carburizing furnace which is an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of the same embodiment.

FIG. 3 is a side sectional view of an essential part of the same embodiment.

FIG. 4 is an enlarged front sectional view of a main part of a first carburized part in FIG.

5 is an enlarged side sectional view of a main part of the first carburized part of FIG.

6 is an enlarged plan sectional view of an essential part of a first carburized part in FIG. 1. FIG.

FIG. 7 is an enlarged view of a main part of the half-split type door shown in FIGS. 4 and 5;

FIG. 8 is a diagram showing an example of an object to be processed and an example of the form of a tray.

FIG. 9 is a view showing one working state in the vacuum carburizing furnace of the same example.

FIG. 10 is a diagram showing a state of action subsequent to FIG. 9;

FIG. 11 is a view showing a state of action following FIG.

FIG. 12 is a diagram showing a state of action subsequent to FIG. 11;

FIG. 13 is a diagram showing a state of action subsequent to FIG. 12;

FIG. 14 is a view showing a main part of a vacuum carburizing furnace according to another embodiment of the present invention.

[Explanation of symbols]

10 Vacuum carburizing furnace (heat treatment furnace) 20 Temperature rising and soaking chamber 22,24 Carburizing chamber (heating chamber) 26,28 gas cooling room 30 Purge chamber 77 accommodation room 78 walls 80,90 doorway 82 door 92 airtight door 116 heater 120 gas supply port W to be processed

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F27B 5/04 F27B 5/04 5/13 5/13 (72) Inventor Satoshi Hori Atsuta Ward, Nagoya City, Aichi Prefecture Rokuno 1-chome 2-5 Kozo Works, Daido Steel Co., Ltd. (72) Inventor Noriyuki Matsumoto 1-2-5 Rono 1-chome, Atsuta-ku, Nagoya-shi, Aichi Daido Steel Co., Ltd. Kozo Works F-term (reference) 4K028 AA01 AB01 AC03 4K034 BA01 BA10 CA04 CA05 EB39 FA01 FB15 4K061 AA01 AA05 BA02 CA21 DA05 FA14 HA09

Claims (5)

[Claims] 1. A heater and a gas supply port are provided in the heating chamber, and a gas for heating the object to be processed inserted into the heating chamber by the heater and acting on the object to be processed is supplied from the gas supply port. In the possible heat treatment furnace, a gas cooling chamber is provided on the lower side of the heating chamber, and the object to be treated taken out downward from the heating chamber can be gas cooled. Characteristic heat treatment furnace. 2. The heating chamber according to claim 1, wherein the heating chamber heat-treats the object to be treated under a reduced pressure, and the object to be treated is vertically disposed between the heating chamber and the gas cooling chamber. A door for opening and closing is provided, an airtight door for opening and closing the door is provided, and the gas cooling chamber is configured to be an airtight chamber when the airtight door is closed. Heat treatment furnace. 3. The heating chamber according to claim 2, wherein the heating chamber is housed in a housing chamber above the gas cooling chamber,
The entrance and exit are provided in the lower wall of the heating chamber and the wall that separates the accommodation chamber and the gas cooling chamber, and the entrance and exit of the lower wall has a door that also serves as a heat shield, and the partition wall. The heat-treating furnace is characterized in that the airtight door is provided at the entrance and exit of the chamber, and a double door structure is provided between the heating chamber and the gas cooling chamber. 4. The heat treatment furnace according to claim 1, wherein at least two heat treatment units each including the heating chamber and the lower gas cooling chamber are provided in series. 5. The heat treatment furnace according to claim 1, wherein the heat treatment unit including the heating chamber and the gas cooling chamber is a carburizing unit.