JP5330651B2 - Heat treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress outdoor air from flowing into an oil tank chamber with respect to a heat treatment method and a heat treatment apparatus for heat-treatment a material to be treated, such as a steel material. <P>SOLUTION: After the material 2 to be treated is treated under high temperature state in a heat treatment chamber 14, a carry-in/out port 25 provided between the heat treatment chamber 14 and the oil tank chamber 102 is opened, and the material 2 is taken out and moved from the heat treatment chamber 14 to the oil tank chamber 102 through the carry-in/out port 25. Then, the material 2 is dipped into an oil tank 103 in the oil tank chamber 102 to be oil-cooled, and the material 2 is taken out from the oil tank 103. Thereafter, an oil tank chamber carry-out port 111 is opened, and the material 2 is carried out from the oil tank chamber 102 through the oil tank chamber carry-out port 111. In this process, when the carry in/out port is opened, when the material 2 is dipped into the oil vessel 103 and when the oil vessel carry-out port 111 is opened/closed, inert gas is supplied to the oil tank chamber. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a heat treatment method of heat-treating an object to be processed, for example, steel or the like.

  Conventionally, as an example of a heat treatment facility for heat treating an object to be treated such as steel, a plurality of heat treatment chambers (a preheating chamber, a carburizing chamber, a diffusion chamber, a descending greenhouse, etc.) and an oil bath chamber for oil quenching (oil cooling) are provided. In addition, the pre-heat treatment, carburizing treatment, diffusion treatment, temperature lowering treatment, etc. are continuously performed while moving the treatment object to each heat treatment chamber in order, and then the treatment object is immersed in the oil tank in the oil tank chamber, and oil quenching is performed. A continuous gas carburizing facility is known (see Patent Documents 1 and 2).

  In such a continuous gas carburizing equipment, for example, a descending greenhouse (the most downstream heat treatment chamber) and an oil tank chamber are provided adjacent to each other, and in order to carry the object to be treated from the descending greenhouse into the oil tank chamber. And a loading / unloading door that opens and closes the loading / unloading port. An oil tank for immersing the object to be processed is installed in the lower part of the oil tank chamber. Furthermore, an oil tank chamber carry-out port for carrying out the object to be processed from the oil tank chamber to the outside of the continuous gas carburizing equipment and an oil tank chamber carry-out door for opening and closing the oil tank chamber carry-out port are provided. Further, an exhaust (exhaust mechanism) for exhausting the oil tank chamber is provided at the ceiling of the oil tank chamber.

  In addition, the entrance / exit door is provided with a communication hole that allows communication between the descending greenhouse side and the oil tank chamber side. That is, during heat treatment, the inside of the descending chamber is set to a positive pressure with respect to the external pressure, but the processing gas in the descending chamber is appropriately allowed to flow into the oil tank chamber through the communication hole even when the entrance / exit is closed by the entrance / exit door. Can be exhausted through exhaust. By adjusting the amount of exhaust, the pressure in the descending greenhouse, and hence the pressure in the preheating chamber, carburizing chamber, diffusion chamber, etc. can be adjusted.

  By the way, the atmospheric temperature and pressure in the oil tank chamber are likely to fluctuate rapidly, and in the exhaust, exhaust in the oil tank chamber and intake of outside air are repeated alternately. For example, when the inlet / outlet is opened in a state where the atmospheric temperature in the descending greenhouse is higher than that in the oil tank chamber (for example, about 850 ° C.), radiant heat is given from the descending greenhouse to the oil chamber and the oil chamber is heated rapidly. Is done. Then, the gas in the oil tank chamber tends to expand, the pressure in the oil tank chamber rapidly increases, and becomes a positive pressure with respect to the pressure outside the continuous gas carburizing equipment. Therefore, a large amount of gas in the oil tank chamber is exhausted through the exhaust. Thereafter, when the loading / unloading port is closed, the radiant heat of the descending greenhouse is not given to the oil tank chamber, and the atmospheric temperature and pressure in the oil tank chamber are rapidly reduced. Then, exhaust is not performed, and the outside air flows into the oil tank chamber through the exhaust. Next, when the object to be processed is immersed in the oil in the oil tank, the object to be processed is rapidly cooled from a high temperature state (about 850 ° C.), and the oil in the oil tank is rapidly heated. Then, the oil in the oil tank boils, oil vapor is generated, and the pressure in the oil tank chamber increases rapidly. Also at this time, the gas (oil vapor or the like) in the oil tank chamber is exhausted through the exhaust. Thereafter, when the atmospheric temperature in the oil tank chamber and the temperature of the oil are lowered and no oil vapor is generated, the pressure in the oil tank chamber is reduced, exhaust is not performed, and the outside air again flows into the oil tank chamber through the exhaust.

JP 2006-152417 A JP 2005-248226 A

However, in the conventional heat treatment method, when the outside air flows into the oil tank chamber through the exhaust, the atmosphere in the oil tank chamber or the heat treatment chamber is disturbed, which may adversely affect the heat treatment performance. For example, in continuous carburization of steel, when oxygen (O ₂ ) in the outside air comes into contact with the object to be processed in the oil tank chamber, the surface of the object to be processed is oxidized and discolored (oxidation coloring), and the quality of the object to be processed decreases. There was a problem to do. Further, when the outside air that has flowed into the oil tank chamber enters the heat treatment chamber through the carry-in / out port, oxygen in the outside air reacts with the carburizing gas in the heat treatment chamber, resulting in a decrease in CP (carbon potential) of the heat treatment chamber. In that case, it is necessary to increase the CP by increasing the processing time in the heat treatment chamber or increasing the supply amount of the processing gas, which is inefficient.

  As a method for suppressing the outside air from flowing into the oil tank chamber or the heat treatment chamber, or a method for discharging the outside air flowing into the oil tank chamber or the heat treatment chamber, for example, the supply flow rate of the processing gas supplied into the heat treatment chamber is increased. By increasing the flow rate of the processing gas introduced into the oil tank chamber through the communication hole of the loading / unloading door or the loading / unloading port from the heat treatment chamber and the flow rate of the gas exhausted from the oil tank chamber through the exhaust, the oil tank chamber is treated with the processing gas. It is also possible to purge with However, in this case, there is a problem that the consumption of the processing gas increases and the cost required for the processing gas increases. In addition, in a heat treatment facility having a plurality of heat treatment chambers, such as a continuous gas carburizing facility, it is necessary to allow the treatment gas to flow into the oil tank chamber in consideration of the flow of the treatment gas between the heat treatment chambers. There is a problem that it becomes difficult to control the heat treatment atmosphere (for example, the composition of each heat treatment chamber, CP, etc.) in each heat treatment chamber. In particular, there was a limit to the control of CP in each heat treatment chamber.

This invention is made | formed in view of said point, and it aims at providing the heat processing method which can suppress that external air flows in into an oil tank chamber.

In order to solve the above-described problems, according to the present invention, there is provided a heat treatment method in which an object to be treated that has been treated in a heat treatment chamber of a continuous furnace at a high temperature is oil-cooled in an oil bath chamber. Open the exhaust mechanism for exhausting the oil tank chamber and the state where the atmosphere temperature of the heat treatment chamber is higher than the atmosphere temperature of the oil tank chamber, and the oil tank chamber outlet is closed. In such a state, a loading / unloading port provided between the heat treatment chamber and the oil tank chamber is opened, and an object to be processed is moved from the heat treatment chamber to the oil tank chamber through the loading / unloading port. After moving the object to be processed into the chamber, with the exhaust mechanism closed, the object is immersed in the oil tank while the opening of the inlet / outlet is gradually reduced or after the inlet / outlet is closed. Before letting The supply of the inert gas is started so that the pressure in the tank chamber does not become a negative pressure with respect to the pressure outside the oil tank chamber, and the processing is performed in the oil tank chamber in a state where the inlet / outlet and the oil tank chamber outlet are closed. After the body is immersed in the oil tank, the supply of the inert gas is stopped, and then the object to be treated is taken out from the oil tank, the combustible gas is burned outside the oil tank chamber outlet, and the oil tank chamber outlet In a state where the ambient temperature of the outer side is higher than the ambient temperature of the oil tank chamber, and in a state where the carry-in / out port is closed, the oil tank chamber carry-out port is opened, and the oil tank chamber is processed through the oil tank chamber carry-out port. After the body is unloaded and the object to be processed is unloaded from the oil tank chamber through the oil tank chamber unloading port, the pressure in the oil tank chamber is increased outside the oil tank chamber while the opening degree of the oil tank chamber unloading port is gradually reduced. Against pressure Starting the supply of the inert gas so as not to negative pressure Te, after closing the oil tank chamber outlet port, and wherein the stopping the supply of the inert gas, the heat treatment method is provided.

Also, in a state of closing the exhaust mechanism, is immersed workpiece to said oil tank, after immersion of the workpiece in the oil tank, open the exhaust mechanism, thereafter, taken out workpiece from said oil tank You may do it. Furthermore, the exhaust mechanism is opened, the oil tank chamber outlet is opened, and then the exhaust mechanism is closed with the atmospheric temperature outside the oil tank chamber outlet being higher than the atmospheric temperature of the oil tank chamber. Thus, the opening degree of the oil tank chamber outlet may be gradually reduced. The exhaust mechanism includes a gas channel that can be opened and closed, and a second gas channel that has a smaller channel cross-sectional area than the gas channel and is always open to the outside. You may provide the burner which injects combustible gas with respect to the external air taken in through a flow path, and the burner which ignites the waste gas of the said oil tank chamber.

  The inert gas may be nitrogen gas. The heat treatment chamber may be a descending chamber of a heat treatment furnace that performs gas carburization of an object to be processed.

  According to the present invention, by supplying an inert gas to the oil tank chamber, it is possible to prevent the outside air from flowing into the oil tank chamber, the atmosphere of the oil tank chamber or the heat treatment chamber is disturbed by the outside air, and the heat treatment is adversely affected. Can be prevented. For example, in the continuous carburizing treatment of steel, it is possible to prevent the object to be treated in the oil tank chamber from being oxidized and colored by oxygen in the outside air. Further, it can be prevented that oxygen in the outside air reacts with the carburizing gas in the heat treatment chamber, that is, the CP in the heat treatment chamber is lowered.

  Further, it is possible to supply the outside air to the oil tank chamber without increasing the supply flow rate of the processing gas supplied into the heat treatment chamber (that is, the flow rate of the processing gas supplied from the heat treatment chamber to the oil tank chamber through the communication hole of the loading / unloading door or the loading / unloading port). Can be prevented from flowing in. Therefore, the consumption of the processing gas can be suppressed and the cost required for the processing gas can be reduced.

  Hereinafter, an embodiment according to the present invention will be described based on a continuous gas carburizing facility 1 as a heat treatment facility with reference to the drawings. As shown in FIG. 1, the continuous gas carburizing equipment 1 processes the object 2 in a high temperature state while conveying the object 2 to be treated, which is a steel product, in the conveying direction D along the X direction (substantially horizontal direction). A heat treatment furnace 3 for performing gas carburization including preheat treatment, carburization treatment, diffusion treatment, and temperature lowering treatment, and an oil cooling section 4 for performing oil cooling (oil quenching treatment) of the workpiece 2.

  In the furnace body 5 of the heat treatment furnace 3, as a plurality of heat treatment chambers, a preheating chamber 11 that performs preheat treatment (temperature increase) of the workpiece 2, a carburization chamber 12 that performs carburization treatment, and diffusion treatment after carburization treatment are performed. A diffusion chamber 13 and a temperature-decreasing greenhouse 14 for performing a temperature-decreasing process after the diffusion process are arranged in this order in the transport direction D from the entrance side to the exit side. On the inlet side of the furnace body 5, a carry-in inlet 21 for carrying the object 2 to be carried into the furnace body 5 (preheating chamber 11) from the outside of the continuous gas carburizing equipment 1 and a carry-in inlet for opening and closing the carry-in inlet 21. A door 22 is provided. On the outlet side of the furnace body 5, a loading / unloading port 25 for unloading the object 2 from the furnace body 5 (falling room 14) and loading it into the oil cooling unit 4 (oil tank chamber 102 described later), and loading A loading / unloading door 26 that opens and closes the outlet 25 is provided.

  Inside the furnace body 5, wall bodies 31, 32, 33 (partition walls) are provided between the preheating chamber 11 and the carburizing chamber 12, between the carburizing chamber 12 and the diffusion chamber 13, and between the diffusion chamber 13 and the descending chamber 14. Are provided. That is, the interior of the furnace body 5 is divided into four heat treatment chambers by the three wall bodies 31, 32, and 33. In each of the wall bodies 31, 32, and 33, passage ports 41, 42, and 43 that allow the workpiece 2 to pass in the X direction are opened. The passage ports 41, 42, 43 are opened and closed by the open / close doors 51, 52, 53, respectively. A roller conveyor 55 including a plurality of rollers 55 a is provided as a transport mechanism for transporting the workpiece 2 at the lower portion of the furnace body 5.

  The carry-in / out port 25 is provided between the descending greenhouse 14 and the oil cooling unit 4 (oil tank chamber 102 described later). In the illustrated example, the carry-in / out door 26 is provided so as to block the carry-in / out port 25 from the outside of the descending greenhouse 14 (oil tank chamber 102 side). Moreover, it moves up and down in the Z direction (vertical direction) between a closed position that closes the loading / unloading port 25 and an opening position that rises from the closing position and opens the loading / unloading port 25. In addition, the loading / unloading door 26 is provided with a communication hole 26 a that allows communication between the descending greenhouse 14 side and the oil cooling unit 4 side (oil tank chamber 102 described later).

Furthermore, the heat treatment furnace 3, a hydrocarbon gas such as city gas as enriched gas _(C m _{H n)} enriched gas supply passage 71 for supplying, RX gas as converted gas (e.g. CO, _CO 2, H _{2, N 2} or the like gas containing) RX gas supply passage 72 for supplying the supply air air supply passage 73, a nitrogen gas _{(N 2)} nitrogen gas supply passage 74 for supplying is connected.

  The enrich gas supply channel 71 includes a supply channel 71 a for supplying the enrich gas to the carburizing chamber 12, a supply channel 71 b for supplying the enrich gas to the diffusion chamber 13, and a supply channel 71 c for supplying the enrich gas to the descending chamber 14. ing. The RX gas supply path 72 includes a supply flow path 72a for supplying RX gas to the preheating chamber 11, a supply flow path 72b for supplying RX gas to the carburizing chamber 12, a supply flow path 72c for supplying RX gas to the diffusion chamber 13, and a temperature drop A supply flow path 72 d for supplying RX gas to the chamber 14 is provided. The air supply path 73 includes a supply flow path 73 a that supplies air to the preheating chamber 11, a supply flow path 73 b that supplies air to the carburizing chamber 12, and a supply flow path 73 d that supplies air to the descending greenhouse 14. The nitrogen gas supply channel 74 includes a supply channel 74 a for supplying nitrogen gas to the preheating chamber 11, a supply channel 74 b for supplying nitrogen gas to the carburizing chamber 12, and a supply channel 74 c for supplying nitrogen gas to the descending chamber 14. ing.

  Further, the heat treatment furnace 3 is provided with an exhaust 81 (an inlet side exhaust mechanism) that exhausts the inside of the furnace body 5. The exhaust 81 is provided, for example, at the ceiling of the preheating chamber 11 and discharges the gas in the preheating chamber 11 to the outside of the continuous gas carburizing equipment 1. The exhaust 81 takes in outside air to take in outside air into the preheating chamber 11 (atmosphere outside the continuous gas carburizing equipment 1), for example, when the preheating chamber 11 becomes negative pressure with respect to outside pressure. It can also function as a road. That is, the exhaust 81 can function as a gas flow path for exhausting the preheating chamber 11 and taking outside air into the preheating chamber 11. The opening degree of the exhaust 81, that is, the exhaust amount of the exhaust gas in the preheating chamber 11 or the inflow amount of outside air may be adjustable.

  Further, the heat treatment furnace 3 is provided with a stirring mechanism 85 (fan) for stirring the atmosphere in the furnace body 5 at the ceiling of the preheating chamber 11, the carburizing chamber 12, the diffusion chamber 13, and the descending chamber 14. Although not shown, heaters for heating the atmosphere in the furnace body 5 are provided in the preheating chamber 11, the carburizing chamber 12, the diffusion chamber 13, and the descending chamber 14, respectively.

  The oil cooling unit 4 has a configuration in which an oil tank chamber 102 (cooling chamber) is formed inside the oil cooling unit housing 101, and an oil tank 103 that stores oil (coolant) in the lower part of the oil tank chamber 102. Is provided. Further, the oil cooling unit 4 transports the workpiece 2 in the transport direction D in the oil tank chamber 102 and moves up and down in the Z direction between the oil tank 103 and the oil tank 103 (elevator). Is provided.

  On the outlet side of the oil cooling unit casing 101, an oil tank chamber outlet 111 for discharging the object 2 from the oil tank chamber 102 to the outside of the continuous gas carburizing facility 1, and an oil tank chamber outlet for opening and closing the oil tank chamber outlet 111. A door 112 is provided. In the illustrated example, the oil tank chamber outlet door 112 is provided so as to close the oil tank chamber outlet 111 from the outside of the oil tank chamber 102. Further, the oil tank chamber carry-out port 111 is moved up and down in the Z direction between a closed position where the oil tank chamber carry-out port 111 is closed and an open position where the oil tank chamber carry-out port 111 is opened from the closed position.

Furthermore, on the outside of the oil tank chamber outlet 111 (outside of the oil tank chamber outlet door 112), a burner 117 (a discharge unit burner) that injects combustible gas (hydrocarbon-based gas, C _m H _n ) into the outside air. ) Is provided. The burner 117 is provided in the vicinity of the lower edge of the oil tank chamber outlet 111 in the illustrated example. That is, the plurality of injection ports are provided so as to be arranged along the lower edge portion of the oil tank chamber outlet 111. Moreover, it directs so that combustible gas may be injected toward upper direction. With this configuration, combustible gas is injected into the outside air that is about to enter the oil tank chamber 102 through the oil tank chamber outlet 111, and oxygen (O ₂ ) in the outside air is consumed for combustion of the combustible gas. . As the burner 117, for example, a so-called curtain burner may be used.

  Further, the RX gas supply path 72 and the nitrogen gas supply path 74 described above are connected to the oil cooling unit 4. That is, a supply flow path 72e for supplying RX gas to the oil tank chamber 102 and a supply flow path 74e as an inert gas supply path for supplying nitrogen gas as an inert gas (low oxygen concentration gas) to the oil tank chamber 102 are provided. It has been. An opening / closing valve 115 for opening and closing the supply flow path 72e is interposed in the supply flow path 72e. An opening / closing valve 116 for opening and closing the supply flow path 74e is interposed in the supply flow path 74e.

  Further, the oil cooling unit 4 is provided with an exhaust 120 (exit side exhaust mechanism) as an exhaust mechanism for exhausting the oil tank chamber 102. The exhaust 120 is provided, for example, on the ceiling of the oil tank chamber 102, and discharges the gas in the oil tank chamber 102 to the outside of the continuous gas carburizing equipment 1. The exhaust 120 can also function as an outside air intake path that takes in outside air into the oil tank chamber 102, for example, when the oil tank chamber 102 has a negative pressure with respect to the external pressure. That is, the exhaust 120 can also function as a gas flow path for exhausting the oil tank chamber 102 and taking outside air into the oil tank chamber 102. The opening degree of the exhaust 120, that is, the exhaust amount of exhaust gas in the oil tank chamber 102 or the inflow amount of outside air may be adjustable.

  Next, the heat processing method of the to-be-processed object 2 using the continuous gas carburizing equipment 1 comprised as mentioned above is demonstrated.

First, in the continuous gas carburizing equipment 1 before the workpiece 2 is carried in, the atmosphere (atmosphere temperature, pressure, composition, CP in the preheating chamber 11, the carburizing chamber 12, the diffusion chamber 13, the descending greenhouse 14, and the oil tank chamber 102 is provided. (Carbon potential) and the like are adjusted to predetermined processing conditions. For example, the temperature of the preheating chamber 11 is about 930 ° C, the temperature of the carburizing chamber 12 is about 930 ° C to 950 ° C, the temperature of the diffusion chamber 13 is about 930 ° C to 950 ° C, and the temperature of the descending chamber 14 is about 850 ° C. Adjusted to degree. The CP value of the preheating chamber 11 is about 0.8%, the CP value of the carburizing chamber 12 is about 1.2%, the CP value of the diffusion chamber 13 is about 0.8%, and the CP value of the descending chamber 14 Is adjusted to about 0.8%. Note that CP is a value indicating the carburizing ability in the heat treatment atmosphere, and is represented by the partial pressure of CO and O ₂ (P _CO / P _O2 ^1/2 ) in the heat treatment atmosphere.

  Adjustment of the atmosphere in the preheating chamber 11, the carburizing chamber 12, the diffusion chamber 13, the descending chamber 14, and the oil tank chamber 102 is based on the heating value of a heater (not shown), the supply flow rate of the rich gas through the rich gas supply channel 71, The supply flow rate of RX gas, the supply flow rate of air through the air supply passage 73, the supply flow rate of nitrogen gas through the nitrogen gas supply passage 74, the exhaust amount by the exhaust 81 in the heat treatment furnace 3, the exhaust amount by the exhaust 120 in the oil cooling section 4 and the like It is performed by adjusting each.

  Also, the carry-in port 21, the passage ports 41, 42, 43, the carry-in / out port 25 of the heat treatment furnace 3, and the oil tank chamber carry-out port 111 of the oil cooling unit 4 are a carry-in door 22, open / close doors 51, 52, 53, a carry-in / out door. 26, closed by an oil tank chamber exit door 112.

  Further, the gas in the continuous gas carburizing facility 1 can move from the descending greenhouse 14 side toward the entrance side, for example, as shown in FIG. That is, the passage ports 41, 42, 43 are not completely sealed, and a gap through which the gas in the furnace body 5 can pass is formed, for example, above the open / close doors 51, 52, 53. The gas in the furnace body 5 flows from the descending greenhouse 14 through the upper and lower doors 53, 52, 51 in the order of the diffusion chamber 13, the carburizing chamber 12, and the preheating chamber 11, and the continuous gas carburizing equipment 1 from the preheating chamber 11 through the exhaust 81. Can be exhausted outside. Thus, when the gas in the furnace body 5 flows from the diffusion chamber 13 side toward the carburizing chamber 12 side, the CP value of the carburizing chamber 12 is maintained at a higher value than the CP value of the diffusion chamber 13 and the like. It becomes easy. Further, since the descending greenhouse 14 and the oil tank chamber 102 communicate with each other through the communication hole 26 a, the processing gas (enrich gas, RX gas, etc.) in the descending greenhouse 14 is caused to flow into the oil tank chamber 102, and the oil tank chamber 102 is allowed to perform an exhaust. 120 can be exhausted to the outside of the continuous gas carburizing equipment 1. Thus, in the continuous gas carburizing equipment 1, a gas flow from the descending greenhouse 14 toward the preheating chamber 11 (Excess 81) and a gas flow from the descending greenhouse 14 toward the oil tank chamber 102 (Excess 120) are formed. Thereby, the heat treatment atmosphere in each heat treatment chamber is appropriately adjusted.

As described above, in the state where the atmosphere in the continuous gas carburizing equipment 1 is adjusted to predetermined processing conditions, the inlet 21 of the heat treatment furnace 3 is opened, and the workpiece 2 is transferred into the preheating chamber 11 through the inlet 21. Then, the carry-in port 21 is closed. When opening and closing the carry-in port 21, the atmosphere (outside air) outside the continuous gas carburizing equipment 1 flows into the furnace body 5 (preheating chamber 11). When 42 and 43 are closed by the open / close doors 51, 52 and 53, the outside air flows from the preheating chamber 11 into the carburizing chamber 12, the diffusion chamber 13 and the descending greenhouse 14 through the passage ports 41, 42 and 43. Can be prevented. That is, it is possible to prevent the oxygen (O ₂ ) in the outside air from reacting with the carburizing gas and reducing the CP, and the heat treatment atmosphere of the carburizing chamber 12, the diffusion chamber 13, and the descending chamber 14 can be suitably maintained.

  The object to be processed 2 carried into the heat treatment furnace 3 is sequentially conveyed to the preheating chamber 11, the carburizing chamber 12, the diffusion chamber 13, and the descending chamber 14 by the roller conveyor 55, and is processed in a high temperature state. That is, the preheating process in the preheating chamber 11, the carburizing process in the carburizing chamber 12, the diffusion process in the diffusion chamber 13, and the temperature lowering process in the descending greenhouse 14 are sequentially performed.

  In addition, after moving the to-be-processed object 2 from the preheating chamber 11 to the carburizing chamber 12, another to-be-processed object 2 can be carried in into the preheating chamber 11 from the carrying-in entrance 21, and can be processed continuously. That is, in the heat treatment furnace 3, a plurality of objects to be processed 2 can be continuously processed in parallel.

  When the temperature lowering process in the descending greenhouse 14 is completed, the process in the oil cooling unit 4 is performed. FIG. 3 shows steps performed in the oil cooling unit 4. 4-9 has shown the state of the oil cooling part 4 in order.

  First, the loading / unloading door 26 is separated from the loading / unloading port 25, the loading / unloading port 25 is opened, and the oil tank chamber 102 is connected to the descending greenhouse 14 (see FIG. 4). And the to-be-processed object 2 is moved to the oil tank chamber 102 from the descending greenhouse 14 through the carrying-in / out opening 25, and is delivered on the conveyance elevator 105.

In the oil cooling section 4, before opening the loading / unloading port 25, the oil tank chamber loading / unloading port 111 is closed by the oil tank chamber loading / unloading door 112, and then the nitrogen gas supply channel 74 (supply channel 74e) to the oil tank chamber 102. Nitrogen gas may be supplied to the inside, the oil tank chamber 102 may be purged with nitrogen gas, and oxygen (O ₂ ) may be discharged from the oil tank chamber 102. That is, the oil tank chamber 102 may be made substantially oxygen-free. If it does so, it can prevent that the to-be-processed object 2 is oxidatively colored with the oxygen in the external air which remained in the oil tank chamber 102, and that oxygen flows in into the temperature falling room 14, and CP falls.

  Thus, when the loading / unloading port 25 is opened when the workpiece 2 is carried into the oil tank chamber 102, the ambient temperature in the descending greenhouse 14 is higher than the atmospheric temperature in the oil tank chamber 102. That is, the temperature difference between the descending greenhouse 14 and the oil tank chamber 102 is large. In this state, when the loading / unloading port 25 is opened, the radiant heat of the descending greenhouse 14 is given to the oil tank chamber 102 through the loading / unloading port 25, and the gas in the oil tank chamber 102 is rapidly heated and tends to expand. Further, when the loading / unloading port 25 is opened and closed, the oil tank chamber loading / unloading port 111 is in a closed state, so that the gas in the oil tank chamber 102 does not escape to the outside of the oil tank chamber 102 through the oil tank chamber loading / unloading port 111. Can not. Therefore, the pressure in the oil tank chamber 102 rises more rapidly than the pressure before the loading / unloading port 25 is opened, and becomes a positive pressure with respect to the pressure outside the continuous gas carburizing facility 1. On the other hand, the exhaust 120 remains open, and the gas in the oil tank chamber 102 can escape to the outside only through the exhaust 120 substantially. Therefore, the pressure in the oil tank chamber 102 is reduced by exhausting the exhaust 120. Thereby, it is possible to prevent the gas in the oil tank chamber 102 from flowing into the descending greenhouse 14 (reverse flow).

  When the workpiece 2 is loaded into the oil tank chamber 102, the loading / unloading port 25 is closed by the loading / unloading door 26 (see FIG. 5). Further, when the loading / unloading port 25 is closed, it is preferable to supply nitrogen gas into the oil tank chamber 102 from the nitrogen gas supply channel 74 (supply channel 74e). Thereby, it can prevent that the pressure of the oil tank chamber 102 falls rapidly. The gas (nitrogen gas, processing gas, etc.) in the oil tank chamber 102 is exhausted to the outside as exhaust gas through the exhaust 120.

  That is, when the loading / unloading port 25 is blocked by the loading / unloading door 26, the radiant heat of the descending greenhouse 14 is blocked by the loading / unloading door 26 and is not given to the oil tank chamber 102, and the ambient temperature in the oil tank chamber 102 rapidly decreases. . For this reason, the gas in the oil tank chamber 102 tends to contract, and the pressure in the oil tank chamber 102 rapidly decreases with respect to the pressure when the loading / unloading port 25 is opened, and the pressure outside the continuous gas carburizing equipment 1 is reduced. There is a risk of negative pressure. In this case, a large amount of outside air may be sucked into the oil tank chamber 102 through the exhaust 120. However, when the loading / unloading port 25 is opened and closed, by supplying nitrogen gas into the oil tank chamber 102, it is possible to prevent the pressure in the oil tank chamber 102 from rapidly decreasing, and the oil tank chamber 102 can be used for the continuous gas carburizing equipment 1. Negative pressure with respect to external pressure, that is, outside air can be prevented from being sucked into the oil tank chamber 102 through the exhaust 120. Thereby, the oil tank chamber 102 can be maintained in a substantially oxygen-free state.

  The supply of the nitrogen gas to the oil tank chamber 102 when opening and closing the loading / unloading port 25 is, for example, from the start of closing of the loading / unloading port 25 to the closing of the loading / unloading port 25 (that is, the loading / unloading door 26). Until the opening / closing position of the loading / unloading port 25 gradually decreases until the loading / unloading door 25 is opened, and then the loading / unloading door 26 is disposed at the blocking position. Even after the loading / unloading port 25 is closed by the loading / unloading door 26, the supply of nitrogen gas to the oil tank chamber 102 may be continued, and further, as will be described later, the workpiece 2 is completely immersed in the oil tank 103. After that, before the workpiece 2 is taken out from the oil tank 103, the supply of nitrogen gas to the oil tank chamber 102 may be stopped (see FIG. 3). Then, while the opening degree of the loading / unloading port 25 is small (while the amount of heat given from the descending greenhouse 14 to the oil tank chamber 102 is decreasing), as will be described later, the workpiece 2 is placed in the oil tank 103. It is possible to suppress the pressure in the oil tank chamber 102 from being lowered and the oil tank chamber 102 from becoming a negative pressure even while being immersed in the water. Therefore, it is possible to more reliably prevent outside air from being sucked into the oil tank chamber 102 through the exhaust 120.

  Further, it is preferable that the processing gas flows from the descending greenhouse 14 to the oil chamber 102 in order to maintain the atmosphere of the descending chamber 14 even while supplying nitrogen gas to the oil chamber 102. In other words, the supply flow rate of nitrogen gas to the oil tank chamber 102 is preferably set to such a level that the gas in the oil tank chamber 102 can be prevented from flowing back into the descending chamber 14 and the outside air can be prevented from flowing into the oil tank chamber 102.

  Thus, after the loading / unloading port 25 is closed by the loading / unloading door 26, the workpiece 2 is lowered by the operation of the transport elevator 105 in the oil tank chamber 102 and immersed in the oil stored in the oil tank 103 (FIG. 6). Thereby, the to-be-processed object 2 is oil-cooled. That is, the to-be-processed object 2 processed at about 850 degreeC (above austenitizing temperature) in the temperature drop room 14 is quenched by being cooled with oil. In addition, also when the to-be-processed object 2 is immersed in oil, it is preferable to supply nitrogen gas in the oil tank chamber 102 from the nitrogen gas supply path 74 (supply flow path 74e). Thereby, it can prevent that the pressure of the oil tank chamber 102 falls rapidly. The gas in the oil tank chamber 102 is exhausted to the outside through the exhaust 120.

  When the object 2 is immersed in the oil in the oil tank 103, the object 2 is rapidly cooled from a high temperature state (about 850 ° C.), and the oil in the oil tank 103 is rapidly heated and boils. Therefore, a large amount of oil vapor is generated from the oil tank 103 immediately after the workpiece 2 is immersed in oil. On the other hand, when the workpiece 2 is immersed in oil, since the loading / unloading port 25 and the oil tank chamber loading / unloading port 111 are closed, the gas (nitrogen gas, processing gas, oil vapor, etc.) in the oil tank chamber 102 is loaded. The oil tank chamber 102 cannot escape to the outside through the outlet 25 or the oil tank chamber carry-out port 111. Therefore, the pressure in the oil tank chamber 102 rises rapidly with respect to the pressure before the workpiece 2 is immersed in the oil, and becomes a positive pressure with respect to the external pressure. In addition, the exhaust 120 remains open, and the gas in the oil tank chamber 102 can escape to the outside only through the exhaust 120 substantially. Therefore, the pressure in the oil tank chamber 102 is reduced by exhausting the exhaust 120.

  After a while from the start of oil vapor generation, the temperature in the oil tank chamber 102 and the oil temperature in the oil tank 103 both decrease, and the amount of oil vapor generated decreases (see FIG. 7). In this case, compared to when a large amount of oil vapor is generated (immediately after the workpiece 2 is immersed in the oil), the pressure in the oil tank chamber 102 is greatly reduced, and the outside air passes through the exhaust 120 and the oil tank chamber 102. There is a risk of inhalation. However, the supply of nitrogen gas from the nitrogen gas supply path 74 into the oil tank chamber 102 can suppress the pressure in the oil tank chamber 102 from decreasing. That is, it is possible to prevent the oil tank chamber 102 from becoming a negative pressure with respect to the pressure outside the continuous gas carburizing equipment 1 and to prevent outside air from being sucked into the oil tank chamber 102 through the exhaust 120, thereby making the oil tank chamber 102 substantially oxygen-free. It can be maintained in a state.

  As described above, the supply of the nitrogen gas to the oil tank chamber 102 may be continued from the time when the opening degree of the loading / unloading port 25 is gradually reduced, while the workpiece 2 is immersed in the oil ( While the amount of generated oil vapor is decreasing), the supply of nitrogen gas to the oil tank chamber 102 is continued and before the object 2 is taken out of the oil (before the transport elevator 105 and the object 2 are raised). Alternatively, it may be stopped. If it does so, it can suppress reliably that the pressure in the oil tank chamber 102 falls, while the generation amount of oil vapor reduces. That is, it is possible to reliably prevent outside air from being sucked into the oil tank chamber 102 through the exhaust 120.

  Thus, after the workpiece 2 is oil-quenched by being immersed in the oil in the oil tank 103, the workpiece 2 is pulled up by the operation of the transport elevator 105 and taken out from the oil tank 103 (see FIG. 8). . On the other hand, in the vicinity of the outside of the oil tank chamber outlet 111, the combustible gas is injected from the burner 117, and the combustible gas is combusted. That is, the ambient temperature outside the oil tank chamber outlet 111 is higher than the ambient temperature in the oil tank chamber 102. In this state, the oil tank chamber outlet door 112 is separated from the oil tank chamber outlet 111, and the oil tank chamber outlet 111 is opened. Then, the workpiece 2 is unloaded from the oil tank chamber 102 through the oil tank chamber unloading port 111.

Here, when the oil tank chamber carry-out port 111 is opened, outside air can enter the oil tank chamber 102 through the oil tank chamber carry-out port 111, but in the vicinity of the oil tank chamber carry-out port 111, oxygen (O ₂ ) Is consumed for combustion of the combustible gas (C _m H _n ) injected from the burner 117, and carbon dioxide (CO ₂ ) and water vapor (H ₂ O) are generated. That is, oxygen in an active state that may oxidize the object to be processed 2 is reduced, and an inactive state (a state of carbon dioxide and water vapor) that does not cause the object to be processed 2 to be oxidized is obtained. That is, even if the oil tank chamber carry-out port 111 is opened and the outside air enters the oil tank chamber 102, the outside air is in a state where oxygen in the active state is reduced. Therefore, an increase in the oxygen (O ₂ ) concentration in the oil tank chamber 102 can be suppressed, and the inside of the oil tank chamber 102 can be maintained in a substantially oxygen-free state.

  Further, when the oil tank chamber carry-out port 111 is opened, radiant heat due to combustion of the combustible gas in the burner 117 is given to the oil tank chamber 102, and the gas in the oil tank chamber 102 is rapidly heated and tends to expand. On the other hand, since the loading / unloading port 25 is closed when the oil tank chamber loading / unloading port 111 is opened and closed, the gas in the oil tank chamber 102 cannot escape to the descending greenhouse 14 side through the loading / unloading port 25. Therefore, the pressure in the oil tank chamber 102 rises rapidly with respect to the pressure before the oil tank chamber carry-out port 111 is opened, and becomes a positive pressure with respect to the external pressure. On the other hand, the exhaust 120 remains open, and the gas in the oil tank chamber 102 can escape to the outside through the exhaust 120. Therefore, the pressure in the oil tank chamber 102 is reduced by exhausting the exhaust 120.

  When the workpiece 2 is unloaded from the oil tank chamber 102, the oil tank chamber unloading port 111 is closed by the oil tank chamber unloading door 112 (see FIG. 9). Further, when the oil tank chamber carry-out port 111 is closed, it is preferable to supply nitrogen gas into the oil tank chamber 102 from the nitrogen gas supply channel 74 (supply channel 74e). Thereby, it can prevent that the pressure of the oil tank chamber 102 falls rapidly. The gas (nitrogen gas, processing gas, etc.) in the oil tank chamber 102 is exhausted to the outside through the exhaust 120.

  That is, when the oil tank chamber carry-out port 111 is blocked by the oil tank chamber carry-out door 112, the heat of the burner 117 is blocked by the oil tank chamber carry-out door 112 and is not given to the oil tank chamber 102, and the temperature in the oil tank chamber 102 is increased. Decreases rapidly. For this reason, the gas in the oil tank chamber 102 tends to contract, and the pressure in the oil tank chamber 102 may rapidly decrease with respect to the pressure when the oil tank chamber outlet 111 is opened. In this case, a large amount of outside air may be sucked into the oil tank chamber 102 through the exhaust 120. However, by supplying nitrogen gas into the oil tank chamber 102 when the oil tank chamber outlet 111 is opened and closed, it is possible to prevent the pressure in the oil tank chamber 102 from abruptly decreasing, and the oil tank chamber 102 has a continuous gas carburizing facility. It is possible to suppress the negative pressure relative to the external pressure of 1, that is, the outside air from being sucked into the oil tank chamber 102 through the exhaust 120. Thereby, the oil tank chamber 102 can be maintained in a substantially oxygen-free state.

  The supply of nitrogen gas to the oil tank chamber 102 when the oil tank chamber carry-out port 111 is opened and closed is, for example, from when the oil tank chamber carry-out port 111 is closed until the oil tank chamber carry-out port 111 is closed ( In other words, the oil tank chamber outlet / outlet door 112 may start during the period from when the oil tank chamber outlet / outlet door 112 starts to descend from the open position until the oil tank chamber outlet / outlet door 112 is disposed at the closed position. Even after the chamber carry-out door 112 is disposed at the closed position and the oil tank chamber carry-out port 111 is closed, the supply of nitrogen gas to the oil tank chamber 102 is continued and stopped after a while after the oil tank chamber carry-out port 111 is closed. May be. Then, while the opening degree of the oil tank chamber outlet 111 becomes small (while the amount of heat applied from the burner 117 to the oil tank chamber 102 decreases), the pressure in the oil tank chamber 102 decreases, and the oil tank chamber 102 Can suppress negative pressure. Therefore, it is possible to more reliably prevent outside air from being sucked into the oil tank chamber 102 through the exhaust 120.

  Incidentally, the next object 2 (2 ′) processed in the descending room 14 can be carried into the oil tank chamber 102 after the object 2 is unloaded. At this time, as described above, since the oil tank chamber 102 is substantially in an oxygen-free state, even if the loading / unloading port 25 is opened, oxygen can be prevented from flowing into the descending greenhouse 14. That is, it is possible to prevent the CP of the descending room 14 from decreasing and the object 2 ′ from being oxidized and colored.

  As described above, according to the heat treatment method using the continuous gas carburizing equipment 1, by supplying nitrogen gas from the nitrogen gas supply path 74 (supply flow path 74 e) to the oil tank chamber 102, It is possible to prevent the pressure from being negative with respect to the external pressure, that is, to be equal to or higher than the external pressure. Thereby, it is possible to prevent the outside air from flowing into the oil tank chamber 102, the atmosphere in the oil tank chamber 102 and the furnace body 5 (such as the descending room 14) is disturbed by the outside air, and the heat treatment of the workpiece 2 is adversely affected. Can be prevented.

For example, oxygen (O ₂ ) in the outside air can be prevented from flowing into the oil tank chamber 102, and the oil tank chamber 102 can be maintained in a substantially oxygen-free state. Thereby, it can prevent that oxygen contacts the to-be-processed object 2, ie, the to-be-processed object 2 discolors by oxidation (oxidation coloring). Therefore, the quality of the workpiece 2 can be improved. Further, it is possible to prevent oxygen from penetrating from the oil tank chamber 102 into the descending greenhouse 14 and reacting with the carburizing gas, that is, the CP of the descending greenhouse 14 and the like is lowered. As a result, the preheating chamber 11, the carburizing chamber 12, diffusion It can prevent that CP of the chamber 13 falls. Therefore, it is possible to prevent the processing performance of the heat treatment furnace 3 from being deteriorated, shorten the processing time in the heat treatment furnace 3, and reduce the supply amount of the processing gas in the heat treatment furnace 3.

  In particular, the processing flow supplied to the oil tank chamber 102 from the descending chamber 14 through the communication hole 26a of the loading / unloading door 26 or the loading / unloading port 25 of the processing gas (enrich gas, RX gas, etc.) supplied into the descending chamber 14. Even if the gas flow rate is not increased, it is possible to prevent the outside air from flowing into the oil tank chamber 102 by supplying the nitrogen gas from the nitrogen gas supply path 74 (supply flow path 74e) to the oil tank chamber 102. Therefore, the consumption of the processing gas can be suppressed and the cost required for the processing gas can be reduced.

  Further, the gas flow in the heat treatment furnace 3 can be formed without considering the flow rate of the gas flowing from the descending chamber 14 to the oil tank chamber 102 in order to maintain the oxygen-free state in the oil tank chamber 102. Thereby, it becomes easy to freely control the atmosphere in the furnace 5. For example, the flow rate of the gas flowing from the descending chamber 14 to the oil tank chamber 102 (the downstream flow rate) is reduced as compared with the conventional one, and the flow rate of the gas flowing from the descending chamber 14 or the soaking chamber 13 to the carburizing chamber 12 side ) Can be increased more than before. In other words, the ratio of the upstream flow rate to the downstream flow rate can be improved. Thereby, for example, the CP of the carburizing chamber 12 is increased from about 1.0% of the conventional to about 1.2%, and the CP of the diffusion chamber 13 is decreased from about 1.0% of the conventional to about 0.8%. Can be easily realized. That is, it becomes easy to increase the difference between the CP in the carburizing atmosphere and the CP in the diffusion atmosphere. In this case, both the efficiency of the carburizing process and the efficiency of the diffusion process can be improved, and the processing time of the entire process in the continuous gas carburizing process facility 1 can be shortened.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the above-described embodiment, two steps when the opening / closing of the oil tank chamber 111 are opened and closed until the workpiece 2 is completely immersed in the oil tank 103 until the opening degree of the carry-in / out opening 25 is gradually reduced. In this case, the nitrogen gas is supplied to the oil tank chamber 102, but the timing of supplying the nitrogen gas to the oil tank chamber 102 is not limited thereto. Also, the timing of starting and stopping the supply of nitrogen gas is not limited to that exemplified in the above embodiment. In short, the supply of nitrogen gas may be controlled so that the pressure in the oil tank chamber 102 does not become negative with respect to the outside. That is, nitrogen gas may be supplied at least when there is a possibility that outside air may be sucked in the oil tank chamber 102.

  For example, as shown in FIG. 10, supply of nitrogen gas to the oil tank chamber 102 when opening and closing the loading / unloading port 25 is performed while the opening of the loading / unloading port 25 is reduced (the loading / unloading door 26 moves from the open position to the closed position). May be started before the loading / unloading door 26 is closed (that is, before the loading / unloading door 26 is lowered from the opening position). The supply of nitrogen gas to the oil tank chamber 102 when opening and closing the oil tank chamber outlet 111 is performed while the opening degree of the oil tank chamber outlet 111 is reduced (until the oil tank chamber outlet door 112 moves from the open position to the closed position). It may be started before the closing of the oil tank chamber outlet 111 is started (that is, before the oil tank chamber outlet door 112 is lowered from the opening position). Also in these cases, it is possible to prevent the pressure in the oil tank chamber 102 from decreasing and the outside air from being sucked into the oil tank chamber 102 through the exhaust 120.

  Moreover, although the above embodiment demonstrated the example which supplies nitrogen gas continuously from after making the opening degree of the carrying in / out port 25 small gradually until after the to-be-processed object 2 was completely immersed in the oil tank 103, it was. For example, as shown in FIG. 11, after closing the loading / unloading port 25, the supply of the nitrogen gas is temporarily stopped, and then immediately before the object 2 is lowered to the oil tank 103 (the object 2 is outside the oil tank 103 ( Nitrogen gas after restarting the supply of the nitrogen gas after the transport elevator 105 and the object to be processed 2 are moved to the oil tank 103 and the object to be processed 2 is completely immersed in the oil tank 103. May be stopped. That is, when opening / closing the loading / unloading port 25, nitrogen gas may be supplied in three timings when moving the workpiece 2 to the oil tank 103 and opening / closing the oil tank chamber loading / unloading port 111. Also in this case, it is possible to prevent the pressure in the oil tank chamber 102 from being lowered and the outside air from being sucked into the oil tank chamber 102 through the exhaust 120.

  For example, as shown in FIG. 12, when the loading / unloading port 25 is opened and closed, nitrogen gas is not supplied, and after the loading / unloading port 25 is closed, the workpiece 2 is immersed in the oil tank 103 (untreated) The supply of nitrogen gas is started outside the oil tank 103 (when the body 2 is outside the oil tank 103), and then the transport elevator 105 and the object to be processed 2 move to the oil tank 103, and the object to be processed 2 enters the oil tank 103. After completely immersed, the supply of nitrogen gas may be stopped. That is, nitrogen gas may be supplied in two cases when the workpiece 2 is moved to the oil tank 103 and when the oil tank chamber carry-out port 111 is opened and closed.

  Further, in the above embodiment, the opening degree adjustment of the exhaust 120 provided in the oil cooling unit 4 has not been specifically described. However, the exhaust 120 may be configured to be openable or closable, or the opening degree is adjusted. It may be possible. For example, the opening / closing of the exhaust 120 may be switched or the opening degree of the exhaust 120 may be adjusted according to the pressure in the oil tank chamber 102.

FIG. 13 shows an example when the execution 120 is configured to be openable and closable. In the example shown in FIG. 13, the exhaust 120 includes an excision main body 121 and a cylindrical body 122 provided above the excision main body 121. Inside the exhaust 120, a gas passage 123 (exhaust passage) through which the exhaust gas or the outside air of the oil tank chamber 102 passes is provided. Further, the exhaust 120 has a gas passage switch 125 for opening and closing the gas passage 123, and a burner for injecting a combustible gas (hydrocarbon-based gas, C _m H _n ) to the outside air taken in through the gas passage 123. 126 and 127 (excess burners) are provided.

  The execution body 121 has a substantially cylindrical shape standing in the length direction in the Z direction (substantially vertical direction), and the lower end opening is opened in the ceiling of the oil cooling unit casing 101. The cylindrical body 122 also has a substantially cylindrical shape standing in the length direction in the Z direction, but the inner diameter is larger than the inner diameter of the exhaust body 122. The upper end opening (opening 121a) of the exhaust body 121 and the lower end opening of the cylindrical body 122 are connected to each other. That is, the gas flow path 123 is configured by the internal space of the exhaust body 121 and the internal space of the cylindrical body 122.

  The gas flow path switch 125 includes a lid 131 disposed inside the cylindrical body 122, a lid support member 132 that supports the lid 131, and a lid lifting device 133 that raises and lowers the lid support member 132. ing. The lid 131 has a substantially circular plate shape arranged substantially horizontally, and has a diameter smaller than the inner diameter of the cylindrical body 122 and larger than the inner diameter of the exhaust body 121. That is, the opening 121 a is closed by the lower surface of the lid 131. The lid support member 132 supports the lid 131 from above, and is connected to the lid lifting / lowering device 133 outside the gas flow path 123. The lid lifting / lowering device 133 is provided on the outside of the execution body 121 and the cylindrical body 122 and is fixed to the execution body 121. As the lid lifting / lowering device 133, for example, a cylinder mechanism may be used.

  The burner 126 includes a plurality of injection ports 126a that inject combustible gas. The injection ports 126 a are arranged in a ring shape along the upper end opening of the cylindrical body 122 on the inner peripheral side of the burner 126. The burner 127 is provided above the burner 126 and includes a plurality of injection ports 127a for injecting combustible gas. The injection port 127a is arranged in a ring shape along the upper end opening of the cylindrical body 122 on the inner peripheral side of the burner 127 above the injection port 126a. For example, a ring burner or a curtain burner may be used as the burners 126 and 127.

  In such an exhaust 120, when the lid support member 132 and the lid 131 are integrally lifted from the opening 121a of the exhaust body 121 by the operation of the lid lifting device 133, the lower surface of the lid 131 is moved upward from the opening 121a. The opening 121a is opened. Then, the internal space of the exhaust body 121 is communicated with the internal space of the cylindrical body 122, and the gas flow path 123 is opened. On the other hand, when the lid support member 132 and the lid 131 are integrally lowered and the opening 121a is closed by the lid 131, the internal space of the exhaust body 121 is blocked from the internal space of the cylindrical body 122, and the gas The flow path 123 is closed. In this way, the exhaust 120 can be opened and closed by moving the lid 131.

  The exhaust 120 is preferably open in a normal state, that is, in an exhaustable state, but the opening and closing of the exhaust 120 may be switched according to the pressure in the oil tank chamber 102. For example, when the pressure in the oil tank chamber 102 decreases, that is, for example, when the loading / unloading port 25 is closed after the loading / unloading port 25 is opened in a state where the temperature of the descending chamber 14 is higher than the temperature of the oil tank chamber 102, When the workpiece 2 is immersed in the oil tank 103, when the oil tank chamber carry-out port 111 is closed after the oil tank chamber carry-out port 111 is opened while injecting combustible gas from the burner 117 and burning, the execution 120 is It may be in a closed state. If it does so, it can prevent more reliably that external air flows in into the oil tank chamber 102 through the excess 120. FIG.

  For example, as shown in FIG. 14, the entrance / exit 25 is opened in the state where the execution 120 is open, and then the execution 120 is closed, and the closing of the entrance / exit 25 is started in this state, and the opening / closing of the entrance / exit 25 is opened. The degree may be gradually reduced. Then, when opening the loading / unloading port 25 (that is, when the pressure in the oil tank chamber 102 rises), exhaust can be smoothly performed by the exhaust 120, and while the opening degree of the loading / unloading port 25 is gradually reduced ( That is, when the pressure in the oil tank chamber 102 decreases), the inflow of outside air can be prevented.

  In addition, after the loading / unloading port 25 is closed, the workpiece 2 may be immersed in the oil tank 103 with the execution 120 closed. Then, the exhaust 120 may be opened after the amount of generated oil vapor is reduced, and then the workpiece 2 may be taken out from the oil tank 103. Then, after the workpiece 2 is immersed in the oil tank 103 (that is, when the pressure in the oil tank chamber 102 is reduced), the inflow of outside air can be prevented when the amount of oil vapor generated is reduced.

  Further, with the exhaust 120 opened, the oil tank chamber carry-out port 111 is opened, and then the exhaust 120 is closed. In this state, the oil tank chamber carry-out port 111 is started to be closed, and the oil tank chamber carry-out port 111 is opened. The degree may be gradually reduced. Then, when the oil tank chamber carry-out port 111 is opened (that is, when the pressure in the oil tank chamber 102 rises), the exhaust 120 can be smoothly exhausted, and the opening degree of the oil tank chamber carry-out port 111 is gradually increased. While the pressure is reduced (that is, when the pressure in the oil tank chamber 102 decreases), the inflow of outside air can be prevented. Note that the exhaust 120 may be opened again after the oil tank chamber outlet 111 is closed.

When the exhaust 120 is opened, combustible gas may be injected from the burners 126 and 127. Then, oxygen (O ₂ ) in the outside air existing in the vicinity of the cylindrical body 122 is consumed for combustion of the combustible gas (C _m H _n ) injected from the burners 126 and 127, and carbon dioxide (CO ₂ ). And water vapor (H ₂ O). That is, as described above, since nitrogen gas is appropriately supplied to the oil tank chamber 102, there is little possibility that outside air is sucked into the oil tank chamber 102 through the exhaust 120 even if the exhaust 120 is opened. Even if the oil enters the oil tank chamber 102 through 120, the outside air is in a state in which active oxygen is reduced by the combustion of the combustible gas supplied from the burners 126 and 127. Therefore, it is possible to more reliably prevent the oxygen (O ₂ ) concentration in the oil tank chamber 102 from increasing by burning the combustible gas injected from the burners 126 and 127.

  FIG. 15 shows an example when the opening degree of the exhaust 120 is adjustable. In the example shown in FIG. 15, similar to the above-described Excess 120, the Excess 120 includes an Excess body 121, a cylindrical body 122, a gas flow path 123 (first gas flow path), a gas flow path switch 125, and a burner 126. 127. Furthermore, a second gas flow path 141 that allows exhaust gas or outside air in the oil tank chamber 102 to pass through, and a pilot burner 142 for igniting the exhaust gas in the oil tank chamber 102 are provided.

  One end (lower end) of the second gas channel 141 is opened in the side wall of the exhaust body 121. That is, it is connected to the gas flow path 123 below the opening 121a. The other end (upper end) of the second gas channel 141 is opened in the side wall of the cylindrical body 122. That is, the gas flow path 123 is connected between the opening 121a and the burners 126 and 127. The channel cross-sectional area of the second gas channel 141 is smaller than the channel cross-sectional area of the gas channel 123. The pilot burner 142 is provided near the other end of the second gas flow path 141 below the burners 126 and 127.

  In such an exhaust 120, the gas flow path 123 can be opened and closed, but the second gas flow path 141 is always open. The opening degree of the exhaust 120 can be adjusted in two stages. That is, when the gas flow path 123 is opened, the opening degree of the exhaust 120 increases, and the exhaust gas is exhausted through the gas flow path 123 and the second gas flow path 141. When the gas flow path 123 is closed, the opening degree of the exhaust 120 becomes small, and the exhaust gas is exhausted only through the second gas flow path 141.

  The exhaust 120 is preferably in a state in which the opening degree is increased in a normal state, that is, in a state where exhaust through the gas passage 123 is possible, but depending on the pressure of the oil tank chamber 102, the opening degree (gas passage) 123 may be switched. For example, when the pressure in the oil tank chamber 102 decreases (when the loading / unloading port 25 is closed, when the workpiece 2 is immersed in the oil tank 103, when the oil tank chamber loading / unloading port 111 is closed), in other words, as described above. In the example shown in FIG. 14, when the exhaust 120 is closed), the lid 131 is lowered to close the opening 121a, and the opening degree of the exhaust 120 is reduced. If it does so, it will become difficult to flow in external air into the oil tank chamber 102 through the excess 120, and it will become possible to prevent inflow of external air more reliably.

  Further, when exhausting the oil tank chamber 102, the pilot burner 142 may be operated to ignite the exhaust gas from the oil tank chamber 102. Then, the combustible gas (hydrocarbon gas (CH), carbon monoxide gas (CO), etc.) contained in the exhaust gas is burned, converted into carbon dioxide and water vapor, and discharged to the outside in a safe state. be able to.

  In the above embodiment, it is assumed that the heat treatment facility is a continuous gas carburization facility that performs continuous carburization treatment of the object to be treated 2, the object to be treated is steel, and the heat treatment furnace is a preheating chamber 11, a carburizing chamber 12, Although the heat treatment furnace 3 that performs continuous gas carburization including the diffusion chamber 13 and the descending chamber 14 is described, these are not limited to the above, and the present embodiment can be applied to heat treatment facilities that perform various heat treatments. . For example, the object to be processed may be made of an alloy other than the iron-based alloy. The heat treatment furnace may be a continuous furnace that performs nitriding or carbonitriding, that is, an atmospheric heat treatment furnace including, for example, a carbonitriding chamber or a nitriding chamber as a heat treatment chamber.

  Furthermore, in the above embodiment, the heat treatment chamber adjacent to the oil tank chamber 102 is the descending greenhouse 14, and the loading / unloading port 25 is provided between the descending greenhouse 14 and the oil tank chamber 102. The heat treatment chamber adjacent to the temperature lowering chamber 14 is not limited to the temperature lowering chamber 14, and may be, for example, a soaking chamber that performs soaking after the temperature lowering treatment.

  In addition, although the inert gas is nitrogen gas, it is not limited to nitrogen gas, and may include, for example, argon gas (Ar).

  The present invention can be applied to a heat treatment method that performs carburizing treatment, nitriding treatment, or the like of, for example, steel materials.

It is the schematic longitudinal cross-sectional view which showed the structure of the continuous gas carburizing equipment. It is a schematic longitudinal cross-sectional view explaining the flow of the gas in a continuous gas carburizing installation. It is a flowchart explaining the process in a continuous gas carburizing installation. It is explanatory drawing which showed the state of the oil cooling part when opening a carrying in / out opening. It is explanatory drawing which showed the state of the oil-cooling part when closing a carrying-in / out port. It is explanatory drawing which showed the state of the oil cooling part immediately after making a to-be-processed object immersed in an oil tank. It is explanatory drawing which showed the state of the oil cooling part when it passes for a while since the to-be-processed object was immersed in an oil tank. It is explanatory drawing which showed the state of the oil cooling part when opening an oil tank chamber carrying-out port. It is explanatory drawing which showed the state of the oil cooling part when obstruct | occluding an oil tank chamber carrying-out port. It is a flowchart explaining the process in the continuous gas carburizing equipment concerning another embodiment, and is an explanatory view showing the example which changed the timing which starts supply of nitrogen gas. It is a flowchart explaining the process in the continuous gas carburizing equipment concerning another embodiment, and is an explanatory view showing the example which changed the timing which supplies nitrogen gas. It is a flowchart explaining the process in the continuous gas carburizing equipment concerning another embodiment, and is an explanatory view showing the example which changed the timing which starts supply of nitrogen gas. It is a longitudinal cross-sectional view explaining the structure which made opening and closing possible. It is explanatory drawing which showed the example of the timing which opens and closes an exhaust. It is a longitudinal cross-sectional view explaining the structure which enabled adjustment of the opening degree of execution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous gas carburizing equipment 2 To-be-processed object 3 Heat processing furnace 4 Oil cooling part 11 Preheating room 12 Carburizing room 13 Diffusion room 14 Falling-out room 25 Carry-in / out 26 26 Carry-in / out door 102 Oil tank room 103 Oil tank 111 Oil tank room Carry-out / out 112 Oil tank room Carry-out Door 117 Burner 120 Excess

Claims (6)

A heat treatment method for oil-cooling an object to be treated treated in a high temperature state in a heat treatment chamber of a continuous furnace in an oil bath chamber,
Processing the object to be processed in a high temperature state in the heat treatment chamber;
In a state where the atmospheric temperature of the heat treatment chamber is higher than the atmospheric temperature of the oil tank chamber, in a state where the oil tank chamber carry-out port is closed, and in a state where an exhaust mechanism for exhausting the oil tank chamber is opened,
Opening a loading / unloading port provided between the heat treatment chamber and the oil tank chamber;
Move the object to be processed from the heat treatment chamber to the oil tank chamber through the loading / unloading port,
After moving the object to be processed from the heat treatment chamber to the oil tank chamber, the oil tank is closed while the exhaust mechanism is closed, while the opening of the loading / unloading port is gradually reduced, or after the loading / unloading port is closed. Before immersing the object to be treated, start supplying inert gas so that the pressure in the oil tank chamber does not become negative with respect to the pressure outside the oil tank chamber,
After immersing the object to be treated in the oil tank in the oil tank chamber in a state where the carry-in / out port and the oil tank chamber carry-out port are closed, the supply of the inert gas is stopped,
Thereafter, the object to be treated is taken out from the oil tank,
In the state where the combustible gas is combusted outside the oil tank chamber carry-out port, the atmosphere temperature outside the oil tank chamber carry-out port is higher than the atmosphere temperature of the oil tank chamber, and the carry-in / out port is closed, Open the oil tank chamber exit,
The workpiece is unloaded from the oil tank chamber through the oil tank chamber outlet,
After the workpiece is unloaded from the oil tank chamber through the oil tank chamber outlet, the pressure in the oil tank chamber is reduced with respect to the pressure outside the oil tank chamber while the opening degree of the oil tank chamber outlet is gradually reduced. Start supplying inert gas to avoid negative pressure,
A heat treatment method, wherein the supply of the inert gas is stopped after the oil tank chamber outlet is closed. With the exhaust mechanism closed, the object to be treated is immersed in the oil tank,
After immersing the object to be treated in the oil tank, open the exhaust mechanism,
Then, the to-be-processed object is taken out from the said oil tank, The heat processing method of Claim 1 characterized by the above-mentioned. Open the exhaust mechanism, open the oil tank chamber outlet in a state where the ambient temperature outside the oil tank chamber outlet is higher than the atmosphere temperature of the oil tank chamber,
3. The heat treatment method according to claim 1, wherein the opening degree of the oil tank chamber outlet is gradually reduced with the exhaust mechanism closed. The exhaust mechanism has a gas channel that can be opened and closed, and a second gas channel that has a smaller channel cross-sectional area than the gas channel and is always open to the outside,
The burner which injects combustible gas with respect to the open air taken in through the gas channel, and the burner which ignites the exhaust gas of the oil tub room are provided, The any one of Claims 1-3 characterized by the above-mentioned. Heat treatment method.   The heat treatment method according to claim 1, wherein the inert gas is nitrogen gas.   The heat treatment method according to any one of claims 1 to 5, wherein the heat treatment chamber is a descending chamber of a heat treatment furnace that performs gas carburization of an object to be treated.

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