JPH05187777A - Atmosphere furnace - Google Patents

Abstract

PURPOSE:To prevent stop or reverse flow of atmospheric gas and to prevent oxidation of the surface of a material to be treated. CONSTITUTION:An exhaust mechanism 12 to be forcibly opened or closed irrespective of a pressure in a conveying chamber 5 is provided in the chamber 5, an exhaust mechanism 13 to be automatically opened when the pressure in a delivering chamber 6 becomes predetermined positive pressure is provided in the chamber 6, and the mechanism 12 of the chamber 5 is forcibly opened after an inlet door 2 and an outlet door 3 of a furnace body 4 are closed. Thus, the flow of atmospheric gas in a furnace chamber 4b of the body 4 is set in a direction from the chamber 5 to the chamber 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmosphere furnace in which a protective atmosphere gas (a gas having a component that does not oxidize an object to be treated) is charged into a furnace body for use. By simultaneously opening and closing the entrance door and the exit door provided on both sides of the furnace main body, the object to be processed is carried into the furnace main body from the carry-in chamber, and another heat treatment is performed in the furnace main body. The present invention relates to an atmosphere furnace configured to carry out an object to be processed from the furnace body to a carry-out chamber.

[0002]

2. Description of the Related Art As an atmosphere furnace of this kind, there is a gas carburizing furnace and a refining furnace of an in-furnace metamorphism system having a low furnace pressure. For example, in a gas carburizing furnace of in-reactor conversion system, the inhaled hydrocarbon gas (for example, HC) or CO is converted into a carburizing inert gas in the furnace, resulting in carburizing gas. in addition to CO _2, H ₂ O, these N _2, etc., occurs the exhaust gas.

A continuous gas carburizing furnace is usually equipped with a furnace body filled with a carburizing atmosphere gas, and a carry-in chamber and a carry-out chamber arranged on both sides of the furnace body, respectively.
The entrance door and the exit door provided on both sides of the furnace body are configured to be simultaneously opened and closed. Then, when the entrance door and the exit door are opened, the processed product (workpiece) is carried into the furnace body from the carry-in chamber, and the heated and carburized product is carried out from the furnace body to the carry-out chamber. It is then cooled with oil.

In this type of atmosphere furnace, when a heated object is transferred into the carry-out chamber, the temperature in the carry-out chamber rises and thermal expansion (volume expansion) occurs, and the pressure in the carry-out chamber rises. To do. On the other hand, when the article to be processed is rapidly cooled, the heat source disappears, so that volume contraction occurs and the pressure in the carry-out chamber decreases. Further, in the case of this type of atmospheric furnace, it is necessary to discharge the surplus amount of the atmospheric gas introduced into the furnace chamber (heating chamber) to the outside. Under such circumstances, exhaust mechanisms (exhaust / intake ports) are provided in the carry-in chamber and the carry-out chamber, respectively.

Conventionally, both the exhaust mechanisms provided in the carry-in chamber and the exhaust mechanism are automatically opened only when the pressure inside the chamber is a predetermined positive pressure, and when the pressure inside the chamber is negative pressure. An actuator such as an air cylinder that is configured to be forcibly opened is used.

[0006]

However, in the conventional atmosphere furnace as described above, the exhaust mechanism of the carry-in chamber and the carry-out chamber can control the intake timing by the actuator, but the exhaust timing can be controlled. Since it is automatically performed according to the increase in internal pressure, the actual situation is that the exhaust control cannot be arbitrarily performed. Therefore, there is a problem that the atmospheric gas with a low carbon potential (high dew point) sucked from the exhaust mechanism of the carry-out chamber flows back into the furnace body (heating chamber), and the surface of the object to be treated is oxidized. .. When such an oxidation phenomenon occurs, the appearance of the article to be processed varies, and the fatigue strength decreases.

The present invention has been made to solve such a problem, and an object thereof is to prevent backflow of an atmospheric gas having a low carbon potential from a carry-out chamber to a carry-in chamber and to be processed. An object of the present invention is to provide an atmospheric furnace that can reduce surface oxidation of products.

[0008]

In order to achieve the above-mentioned object, in the present invention, by simultaneously opening and closing an inlet door and an outlet door provided on both sides of a furnace body filled with atmospheric gas, In the atmospheric furnace, the processed product is carried into the furnace body from the carry-in chamber, and another object to be processed that has been heat-treated in the furnace body is carried out from the furnace body to the carry-out chamber. An exhaust mechanism that can be forcibly opened and closed regardless of the pressure in the room is provided in the carry-in room,
An exhaust mechanism that automatically opens when the pressure in the carry-out chamber reaches a predetermined positive pressure is provided in the carry-out chamber, and the exhaust mechanism of the carry-in chamber is forcibly opened after closing the entrance door and the exit door. With this configuration, the flow of the atmospheric gas in the furnace body is directed from the loading chamber to the unloading chamber.

[0009]

[Operation] By shifting the timing of opening the exhaust mechanism on the loading chamber side after closing the inlet door and the exit door of the furnace body, the flow of atmospheric gas in the furnace body (furnace chamber) changes from the loading chamber to the loading chamber. This is the direction to go, and the backflow of atmospheric gas is prevented.

[0010]

FIG. 1 and FIG. 2 show an atmosphere furnace (continuous gas carburizing furnace) 1 for continuous carburizing to which the present invention is applied.
This atmosphere furnace 1 has an entrance door 2 and an exit door 3 on both sides.
A horizontally long furnace body 4, a loading chamber 5 and an unloading chamber (oil tank chamber) 6 that are arranged adjacent to each other on both sides of the furnace body 4, and an oil tank 7 that is continuously provided below the unloading chamber 6. It has.

The above-mentioned entrance door 2 and exit door 3 are constructed to be controlled to be opened and closed at the same time by a driving means (not shown), and when these doors 2 and 3 are opened, the furnace chamber 4a in the furnace body 4 is opened. And the carry-in chamber 5 and the carry-out chamber 6 are in communication with each other. In addition, inside the furnace body 4 (furnace chamber 4
In (a), a predetermined carburizing gas is filled as an atmosphere gas, and the atmosphere gas is agitated by a plurality of in-furnace agitation fans 8.

Further, on the carrying-in chamber 5 side, the articles (work) 9 placed on a work tray (not shown) and successively supplied into the carrying-in chamber 5 are provided in the furnace body 4 one by one. A main pusher 10 that pushes out toward is disposed. Then, as the article 9 to be processed placed on the work tray is pushed out by the main pusher 10 and carried into the furnace body 4, the furnace body 4 is lined up in a line along the longitudinal direction. One by one the processed articles 9 arranged side by side in the direction of arrow A in FIG. 1 and FIG. 2, that is, in the direction from the carry-in chamber 5 to the carry-out chamber 6.

Exhaust mechanisms (exhaust / intake mechanisms) 12 and 13 are provided in the carry-in chamber 5 and the carry-out chamber 6, respectively. Exhaust mechanism 1 on the loading room 5 side
2 is a type that is forcibly opened / closed regardless of the pressure in the carry-in chamber 5, and as shown in FIG. 3, an exhaust pipe 14 connected to the carry-in chamber 5 and an upper end opening of the exhaust pipe 14. A ring burner 15 arranged in the chamber 14a, a pilot burner 16 arranged corresponding to the upper end opening chamber 14a, and a valve body (sealing plate) arranged in the upper end opening chamber 14a for opening and closing the exhaust pipe 14 ) 17, and a drive means 19 including an air cylinder 18 for forcibly driving and controlling this valve body. In this example, the valve element 17 is formed of a flat plate, and the valve element 17 is configured to be crimped to the flat valve seat 20 of the exhaust pipe 14.

On the other hand, the exhaust mechanism 13 on the discharge chamber 6 side
Is a conventional type that is automatically opened only when the pressure in the carry-out chamber 6 is a positive pressure, and as shown in FIG.
An exhaust pipe 21 connected to the carry-out chamber 6, a ring burner 22 arranged in the upper end opening chamber 21a of the exhaust pipe 21, a pilot burner 23 arranged corresponding to the upper end opening chamber 14a, A valve element (seal plate) 24 that is arranged in the upper end opening chamber 21a and is automatically differentiated only when the pressure in the unloading chamber 6 is a predetermined positive pressure to open and close the exhaust pipe 21, and the unloading chamber 6 The driving means 26 is composed of an air cylinder 25 and the like for forcibly opening the valve element 24 when the pressure is a negative pressure. The above-mentioned valve body 24 has a spherical sealing surface 24a.
This valve body 24 is composed of a crescent-shaped member having a cross section
The sealing surface 24a is configured to be pressed against the spherical valve seat 27 of the exhaust pipe 21.

By the way, as described above, the exhaust mechanism 13 on the carry-out chamber 6 side is conventionally used and has a spherical sealing surface, whereas the exhaust mechanism 12 on the carry-in chamber 5 side is conventional. Unlike, it has a flat sealing surface. Therefore, as compared with the exhaust mechanism 13, the exhaust mechanism 12 is easier to process and can easily correct the contact of the seal surface, and the airtightness and reliability of the seal surface are high, and the atmosphere gas It is possible to minimize the outflow.

Further, as shown in FIG. 1, an elevating plate 28 is provided inside the discharge chamber 6 so that it can move up and down between the oil tank 7 and the discharge chamber 6. ing.
Further, the carry-out chamber 6 has an exit door 29 for carrying out the processed product.
Is provided. On the other hand, in the carry-in chamber 5, as shown in FIG. 2, an entrance door 30 for carrying in the article to be processed is provided, and a sub-pusher 31 is arranged corresponding to the entrance door 30.

Next, the operation and action when carburizing the article 9 to be treated in the atmosphere furnace 1 having the above-described structure will be described.

First, in operating the atmosphere furnace 1, the furnace chamber 4a of the furnace body 4 is filled with a carburizing atmosphere gas and the furnace stirring fan 8 is operated to make the atmosphere gas uniform in the furnace chamber 4a. Fill up. In addition, an appropriate amount of oil liquid is stored in the oil tank 7.

Under this condition, when the inlet door 2 and the outlet door 3 of the furnace body 4 are simultaneously opened by a driving means (not shown), the main pusher 10 is operated in synchronization with this. Along with this, the article to be processed 9 transferred from the previous process line and transferred into the carry-in chamber 5 by the sub pusher 31.
The object 9 to be processed which has been placed on the work tray in advance is pressed by the main pusher 10 and transferred into the furnace chamber 4a of the furnace body 4 through the inlet door 2. Then, in response to the operation of loading the article to be processed 9 into the furnace chamber 4a, the furnace chamber 4a
Each of the other products to be processed 9 arranged in a line in the inside is intermittently moved one by one in the direction of arrow A (direction toward the exit door 3), and passes through the exit door 3 into the carry-out chamber 6. The processed products 9'are extruded one by one intermittently.

In the furnace chamber 4a, the article 9 to be treated is heated to a predetermined temperature in an atmosphere gas and carburized. Then, the object 9 ′ which has been carburized and sent out from the furnace chamber 4 a into the carry-out chamber 6 is placed on the elevating plate 28, and immediately after that, the elevating plate 28 is lowered. As a result, the processed product 9 '
Is soaked in the oil liquid in the oil tank 7 and rapidly cooled, and thereafter,
The elevating plate 28 is raised together with the article 9'to be processed. And
The processed article 9 ′ that has been processed is transferred to the tray by the main pusher 10, that is, as the exit door 29 of the carry-out chamber 6 is opened at time t ₉ prior to the opening of the entrance door 2 and the exit door 3. It is carried out by a carry-out device such as a fork outside the furnace and sent to the next process. At this time, if the outlet door 29 is opened alone, the pressure P ₀ in the carry-out chamber 6 is greatly reduced. Further, since there are small vent holes (not shown) between the carry-out chamber 6 and the furnace chamber 4a, and between the furnace chamber 4a and the carry-in chamber 5, the pressure P _H in the furnace chamber 4a and the pressure in the carry-in chamber 5 are P _i also changes slightly.

On the other hand, the exhaust mechanisms 12 and 13 of the carry-in chamber 5 and the carry-out chamber 6 operate as shown in the timing chart of FIG.

First, at the beginning of one cycle for treating the article to be treated 9, the entrance door 2 and the exit door 3 of the furnace body 4, the entrance door 30 of the carry-in chamber 5, and the exit door 29 of the carry-out chamber 6 are all It is closed and the lift plate 28 is arranged in the raised position. Thus, when one cycle is started, the entrance door 30 of the carry-in chamber 5 is opened, and the sub-pusher 31 is actuated at a time point t ₂ immediately after the door opening start time point t ₁ . Along with this, the article to be processed 9 in the carry-in chamber 5 is placed at a predetermined position in the carry-in chamber 5 by the sub pusher 31.

[0023] subsequently to (time t ₃₎ furnace inlet door 2 and the exit door 3 of the body 4 is open door started simultaneously, the main pusher 10 starts operating at the time t ₄ immediately thereafter. Along with this, the article to be processed 9 in the carry-in chamber 5 is transferred to the main pusher 1
0, pushed through the entrance door 2 and the furnace chamber 4a of the furnace body 4
It is placed on the work tray inside. After that, the main pusher 10 is returned.

In this manner, when the article 9 to be treated is pushed into the furnace chamber 4a from the carry-in chamber 5, a plurality of the article 9 to be treated, which has been carried into the furnace chamber 4a and aligned in a row, before that. The workpiece 9 ′ that has been moved toward the outlet door 3 side and heated in the furnace chamber 4 a and carburized is pushed out through the outlet door 3 onto the elevating plate 28 in the carry-out chamber 6.

In this case, since the article 9'in the heated state exists as a heat source in the carry-out chamber 6, the pressure P ₀ in the carry-out chamber 6 is rapidly increased to a relatively high positive pressure. .. In response to this, the exhaust mechanism 13 on the discharge chamber 6 side
Is automatically opened from the time point t ₅ immediately after the time point t ₃ (however, at this time, the exhaust mechanism 12 on the carry-in chamber 5 side is
Is closed). Therefore, the thermally expanded atmosphere is discharged to the outside through the exhaust mechanism 13. Along with this, the pressure in the furnace chamber 4a is temporarily reduced from a predetermined positive pressure, and the pressure P ₀ in the carry-out chamber 6 is gradually reduced to approach the atmospheric pressure. Note that the furnace chamber 4a is supplied a predetermined atmospheric gas from the gas supply means, not shown, the time t ₆ after the closing of the inlet door 2 and the exit door 3 is returned to a predetermined positive pressure.

By the way, the atmospheric gas in the carry-out chamber 6 which has been thermally expanded in the carry-out chamber 6 by the article to be treated 9'that is in a heated state, flows out from the exhaust mechanism 13 to the outside and also flows back into the furnace chamber 4a. (The reason is that, since the carry-out chamber 6 has a small volume, the pressure in the carry-out chamber 6 is momentarily higher than that in the furnace chamber 4a). However, in this example, during the volume expansion in the carry-out chamber 6, the exhaust mechanism 12 on the carry-in chamber 5 side is placed under the closed state, so that the outflow of the atmosphere from the carry-in chamber 5 side can be prevented. .. This can prevent the atmosphere having a low carbon potential in the carry-out chamber 3 from flowing into the furnace chamber 4a. as a result,
The atmospheric gas in the furnace chamber 4a always flows in one direction from the carry-in chamber 2 to the carry-out chamber 3 side.

On the other hand, the forced operation type exhaust mechanism 12 on the side of the carry-in chamber 5 is compulsorily opened in synchronization with the closing time t ₇ of the entrance door 2 and the exit door 3. This allows
The surplus atmospheric gas existing in the carry-in chamber 5 is discharged to the outside. Further, the negative pressure generated by the closing of the inlet door 2 and the outlet door 3 is compensated by the suction of the ring burner combustion gas, and the pressure in the carry-in chamber 5 is restored to the normal furnace pressure.

The flow of the atmospheric gas will be described below in comparison with the conventional case. That is, conventionally, the period T during which the exhaust mechanism 13 on the unloading chamber 6 side is opened in response to the opening of the entrance door 2 and the exit door 3
(See FIG. 5), the exhaust mechanism 12 on the side of the carry-in chamber 5 is automatically opened at a time point t ₈ earlier than in the case of this example (time point t ₇ ), so that the pressure P _H in the furnace chamber 4a, When the pressure P _i in the carry-in chamber 2 and the pressure P _o in the carry-out chamber 3 suddenly change (decrease) as shown by the broken line in FIG. 5, particularly when P _H ≦ P _o , the flow of the atmospheric gas is stopped, Backflow from the carry-out chamber 3 to the carry-in chamber 2 causes the problem as described above. On the other hand, in the case of this example, the timing of opening the exhaust mechanism 12 on the carry-in chamber 2 side is forcibly shifted from the time point t ₈ to the time point t ₇ , so that the atmosphere inside the carry-out chamber 6 is changed. At the time of thermal expansion, the atmospheric gas is not discharged from the exhaust mechanism 12 on the carry-in chamber 5 side. Therefore, the flow of the atmospheric gas can be prevented from stopping and the backflow can be prevented, and the flow of the atmospheric gas can be set in one direction from the carry-in chamber 2 to the carry-out chamber 3.

The above is a description of one embodiment of the present invention.
The present invention is not limited to the embodiments described above, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the above-mentioned embodiment, the exhaust mechanism 12 on the side of the carry-in chamber 2 is opened at the time t ₇ when the entrance door and the exit door 3 are closed, but the opening time is defined as after the door closing time. You may set so that it may become.

[0030]

As described above, according to the present invention, the forced opening / closing type exhaust mechanism is provided on the carry-in chamber side, and the automatic opening type exhaust mechanism as conventionally used is provided on the carry-out chamber side. After closing the inlet and outlet doors of the furnace body, by forcibly opening the exhaust mechanism on the side of the carry-in chamber, the atmospheric gas in the furnace body is moved in one direction from the side of the carry-in chamber to the carry-out chamber. Since it is designed to flow, it is possible to prevent the flow of the atmospheric gas having a low carbon potential from stopping or the backflow from the carry-out chamber to the carry-in chamber side. As a result, it is possible to prevent the oxidation of the surface of the object to be processed and reduce the variation in the appearance, and it is possible to reduce the surface oxide layer that greatly affects the fatigue strength of the product, so that it is possible to prevent the deterioration of fatigue strength. be able to.

[Brief description of drawings]

FIG. 1 is a side view of an atmospheric furnace according to the present invention.

FIG. 2 is a plan view of the atmosphere furnace.

FIG. 3 is a sectional view of an exhaust mechanism on the side of a carry-in chamber.

FIG. 4 is a cross-sectional view of the exhaust mechanism on the side of the carry-out chamber.

FIG. 5 is a timing chart showing the operation of the atmosphere furnace.

[Explanation of symbols]

 1 atmosphere furnace (continuous gas carburizing furnace) 2 inlet door 3 outlet door 4 furnace body 4a furnace chamber (heating chamber) 5 carry-in chamber 6 carry-out chamber 7 oil tank 9,9 'processed product (work) 12 exhaust on the side of the carry-in chamber Mechanism 13 Exhaust mechanism on the side of the unloading chamber

Claims (1)

[Claims] 1. An object to be processed is carried into the furnace body from a carry-in chamber by simultaneously opening and closing an entrance door and an exit door provided on both sides of the furnace body filled with atmospheric gas.
And, in an atmosphere furnace in which another object to be heat-treated in the furnace body is carried out from the furnace body to the carry-out chamber, an exhaust mechanism that can be forcibly opened and closed regardless of the pressure in the carry-in chamber is provided. An exhaust mechanism, which is provided in the carry-in chamber and automatically opens when the pressure in the carry-out chamber reaches a predetermined positive pressure, is provided in the carry-out chamber, and the exhaust mechanism of the carry-in chamber is provided after closing the entrance door and the exit door. Is configured to be forced into the open state, which
An atmosphere furnace characterized in that a flow of an atmospheric gas in the furnace body is directed from the carry-in chamber to the carry-out chamber.