JP6043551B2 - Heat treatment method - Google Patents

Description

The present invention relates to a heat treatment method , and more particularly to a heat treatment method for quenching a workpiece.

  In a heat treatment method for quenching by heating and cooling a metal material that is an object to be treated, it has been proposed to use a mist cooling type heat treatment apparatus when rapid cooling is required (see Patent Document 1). . In this mist cooling method, for example, by supplying a mist-like cooling medium from the nozzles arranged on the side surface and the top and bottom of the object to be processed, the object to be processed is cooled by latent heat of vaporization. Are better.

  In Patent Document 1, cooling, intermediate cooling stop, and recooling are performed in order to suppress unevenness and bending of the structure of the workpiece during quenching by making use of the cooling efficiency and cooling controllability of this mist cooling method. In the state where the temperature difference between the inside and outside of the object to be treated is relaxed, the object to be treated is cooled to a temperature equal to or lower than the transformation point of the predetermined structure, and the tissue inside and outside the object to be treated is transformed into the predetermined structure almost simultaneously A heat treatment method is disclosed.

JP 2011-202228 A

  In the mist cooling method, a temperature difference occurs between a place where the cooling medium is around and a place where the cooling medium is around. For this reason, for example, in an object to be processed having a shape in which holes, grooves, etc. are formed and the entire outer surface cannot face the nozzle, the structure may become uneven and bend during heat treatment. is there. Further, if the cooling medium is to be supplied uniformly to the outer surface of the object to be processed, there is a problem that it is difficult to increase the amount of the object to be processed due to the arrangement of the nozzles.

The present invention has been made in view of the above problems, and can suppress unevenness and bending of the tissue regardless of the shape of the object to be processed, and can increase the amount of the object to be processed. An object is to provide a heat treatment method .

In order to solve the above problems, the present invention provides a cooling tank that can store an object to be processed, a cooling medium supply unit that stores a cooling medium in the cooling tank, and a submerged object to be stored in the stored cooling medium. An object transporting part to be treated, a cooling medium drainage part for draining a cooling medium stored in the cooling tank after the submergence, and a mist for cooling the mist by supplying a mist-like cooling medium to the object to be treated after the drainage A heat treatment apparatus having a cooling unit is employed.
By adopting this configuration, in the present invention, the cooling medium is accumulated in the cooling tank, the initial cooling is performed by submerging the object to be processed in the cooling medium, and then the cooling medium is drained and the cooling intermediate stop is performed. Re-cool by mist cooling. In the initial cooling in which the temperature difference between the inside and outside of the workpiece is likely to occur, the entire surface of the workpiece can be uniformly cooled by soaking the workpiece in the cooling medium in this way. For this reason, even if holes or grooves are formed in the object to be processed, unevenness and bending of the tissue can be suppressed without causing a temperature difference, and sufficient cooling can be achieved even if the amount of the object to be processed is increased. Is possible.

Moreover, in this invention, the said to-be-processed object conveyance part employ | adopts the structure of pulling up to-be-processed object from the cooling medium stored in the said cooling tank before the said drainage is completed after the said water submergence.
By adopting this configuration, in the present invention, when it takes time to drain the cooling medium stored in the cooling tank, the time during which the object to be processed is partially immersed in the cooling medium becomes longer, and the object to be processed However, it is possible to make it difficult to generate a temperature difference between the upper and lower sides of the object to be processed by pulling up the object to be processed without waiting for the completion of drainage.

Moreover, in this invention, the said to-be-processed object conveyance part employ | adopts the structure pulled up from the cooling medium stored in the said cooling tank during the said waste_water | drain.
By adopting this configuration, in the present invention, the processing object is pulled up from the cooling medium relatively quickly by lowering the liquid level of the cooling medium due to drainage and pulling up the processing object by the processing object transport unit. Therefore, the time during which the object to be processed is partially immersed in the cooling medium is shortened, and it is possible to make it difficult for the temperature difference between the upper and lower parts of the object to be generated.

In the present invention, the cooling medium drainage section includes a drainage tank provided at a position lower than the cooling tank, a drainage pipe having one end communicating with the bottom of the cooling tank and the other end communicating with the drainage tank. And a butterfly valve that opens and closes the pipe of the drainage pipe.
By adopting this configuration, in the present invention, by opening the butterfly valve, the cooling tank and the drainage tank are communicated, and the cooling medium stored with water head pressure from the bottom of the cooling tank is extracted to the drainage tank at once. Therefore, the time required for draining the cooling medium can be shortened.

Moreover, in this invention, the structure of having a cooling medium stirring part which stirs the cooling medium stored in the said cooling tank is employ | adopted.
By adopting this configuration, in the present invention, by providing a water flow to the cooling medium stored in the cooling tank, the cooling medium exchanged heat with the object to be processed flows without staying on the spot. Can be increased.

Moreover, in this invention, the said cooling medium stirring part employ | adopts the structure of providing the flow of a perpendicular direction to the cooling medium stored in the said cooling tank.
By adopting this configuration, in the present invention, it is possible to effectively distribute the cooling medium along the outer surface of the workpiece by applying a flow in the vertical direction to the cooling medium stored in the cooling tank. The cooling efficiency can be further increased.

In the present invention, the mist cooling unit has a nozzle for injecting a cooling medium in a mist shape, and the cooling medium agitating unit injects the cooling medium through the nozzle, thereby cooling the cooling medium. A configuration is adopted in which the cooling medium stored in the tank is stirred.
By adopting this configuration, in the present invention, when the object to be processed is immersed in the cooling medium stored in the cooling tank, a water flow can be applied to the cooling medium using the nozzle of the mist cooling unit. .

Moreover, in this invention, the said cooling medium stirring part employ | adopts the structure that it has a cooling medium circulation part which circulates the cooling medium stored in the said cooling tank.
By adopting this configuration, in the present invention, it is possible to impart a water flow to the cooling medium by circulating the cooling medium stored in the cooling tank.

Moreover, in this invention, the structure that the said cooling medium supply part and the said mist cooling part consist of the same apparatus is employ | adopted.
By adopting this configuration, in the present invention, the number of parts of the device can be reduced, and the size and cost of the device can be reduced.

Further, in the present invention, the step of storing the cooling medium in a cooling tank capable of accommodating the object to be processed, the step of submerging the object to be processed in the stored cooling medium, and the water stored in the cooling tank after the submergence. A heat treatment method including a step of draining the cooling medium and a step of supplying a mist-like cooling medium to the object to be treated and cooling the mist after the drainage is adopted.
By adopting this method, in the present invention, the cooling medium is accumulated in the cooling tank, the initial cooling is performed by submerging the object to be processed in the cooling medium, and then the cooling medium is drained and the cooling intermediate stop is performed. Re-cool by mist cooling. In the initial cooling in which the temperature difference between the inside and outside of the workpiece is likely to occur, the entire surface of the workpiece can be uniformly cooled by soaking the workpiece in the cooling medium in this way. For this reason, even if holes or grooves are formed in the object to be processed, unevenness and bending of the tissue can be suppressed without causing a temperature difference, and sufficient cooling can be achieved even if the amount of the object to be processed is increased. Is possible.

  According to the present invention, it is possible to suppress tissue non-uniformity and bending regardless of the shape of the object to be processed, and to increase the amount of the object to be processed.

It is a section lineblock diagram of the multi-chamber type heat treatment apparatus in a 1st embodiment of the present invention. It is arrow AA sectional drawing in FIG. It is the top view and side view of the cooling-medium drainage apparatus in 1st Embodiment of this invention. It is a flowchart which shows the heat processing operation | movement of the multi-chamber heat processing apparatus in 1st Embodiment of this invention. It is a figure for demonstrating the heat processing operation | movement in 1st Embodiment of this invention. It is a figure for demonstrating the heat processing operation | movement in 1st Embodiment of this invention. It is a graph which shows the temperature change of the to-be-processed object by the heat processing operation | movement in 1st Embodiment of this invention. It is a figure for demonstrating the heat processing operation | movement in 2nd Embodiment of this invention. It is a figure for demonstrating the heat processing operation | movement in 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, a multi-chamber heat treatment apparatus is exemplified as the heat treatment apparatus using the heat treatment method of the present invention.

(First embodiment)
FIG. 1 is a cross-sectional configuration diagram of a multi-chamber heat treatment apparatus S in the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a plan view and a side view of the cooling medium drainage device 21 in the first embodiment of the present invention. 3A corresponds to the cross-sectional view taken along the line BB in FIG. FIG. 3B corresponds to the arrow C diagram in FIG.
The multi-chamber heat treatment apparatus S is a heat treatment apparatus for performing a quenching process on the workpiece X that is a metal part. In the present embodiment, as the workpiece X, for example, steel such as die steel (SKD material) or high-speed steel (SKH material) is targeted.

As shown in FIG. 1, the multi-chamber heat treatment apparatus S includes an intermediate transfer chamber 1, a heating chamber 2, and a cooling chamber (cooling tank) 3.
The intermediate transfer chamber 1 is disposed between the heating chamber 2 and the cooling chamber 3. The intermediate transfer chamber 1 is a chamber for transferring the workpiece X between the heating chamber 2 and the cooling chamber 3, and has a central chamber 1a and a heating elevator chamber 1b as shown in FIG. doing. The central chamber 1a is set in an octagonal shape in plan view, and is a room through which all the workpieces X processed in the multi-chamber heat treatment apparatus S of the present embodiment pass.

  The central chamber 1a has a carry-in / out door 4 serving as an entrance to the multi-chamber heat treatment apparatus S of the present embodiment. For this reason, the workpiece X is carried into the central chamber 1a via the carry-in / out door 4, and the workpiece X is carried out from the central chamber 1a via the carry-in / out door 4. The central chamber 1a is connected to three heating lifting chambers 1b. A plurality of push devices 5 are provided in the intermediate transfer chamber 1, and the object to be processed is moved along a rail installed inside the intermediate transfer chamber 1 by pushing the tray T on which the object to be processed X is placed. X is pushed forward in the horizontal direction and conveyed.

  A cooling chamber 3 is disposed below the central chamber 1a (see FIG. 1). An opening 1a1 that communicates from the central chamber 1a (that is, the intermediate transfer chamber 1) to the cooling chamber 3 is provided at the center of the central chamber 1a. The opening 1a1 can be closed by an upper lid 6 that can be opened and closed. That is, the intermediate transfer chamber 1 and the cooling chamber 3 can be isolated by the opening 1 a 1 being closed by the upper lid 6. In the central chamber 1a, as shown in FIG. 1, an upper lid elevating device 7 for elevating the upper lid 6 is installed. In addition, a mounting table 8 on which the tray T can be mounted is provided on the upper surface of the upper lid 6, and the workpiece X is accommodated in the central chamber 1 a even when the opening 1 a 1 is closed by the upper lid 6. It is configured to be possible.

  The heating lifting chamber 1b is a room for accommodating the workpiece X to be carried into the heating chamber 2 from the intermediate conveyance chamber 1 or the workpiece X carried out from the heating chamber 2 to the intermediate conveyance chamber 1. The heating lift chamber 1b can accommodate the openable / closable floor of the heating chamber 2 and the mounting table 10 installed on the floor, and accommodates the workpiece X together with the mounting table 10. . As shown in FIG. 1, an elevating device 9 for elevating the workpiece X is installed below the heating elevating chamber 1 b, and the elevating device 9 moves the workpiece X together with the mounting table 10 to the heating elevating chamber 1 b. It is moved up and down and conveyed.

  The heating chamber 2 is a cylindrical room for performing the heat treatment of the workpiece X, and is installed above each heating lifting chamber 1b. That is, the multi-chamber heat treatment apparatus S of the present embodiment includes three heating chambers 2. A heater 13 is installed in the heating chamber 2, and the workpiece X is heat-treated by the heat generated by the heater 13. The heater 13 may be silicon carbide (SiC), Fe—Cr—Al alloy, graphite, nickel chromium (Ni—Cr), molybdenum (Mo) or an electric heater using graphite as a heating element, or heating with high frequency power. A heater or the like can be used.

The heating chamber 2 is connected to a gas supply device 14 for supplying an atmosphere forming gas to the inside of the heating chamber 2. The gas supply device 14 supplies, for example, nitrogen gas, acetylene gas, or the like as the atmosphere forming gas to the heating chamber 2. The heating chamber 2 includes a fan 15 that stirs the internal atmosphere in order to uniformly heat the workpiece X. Furthermore, the heating chamber 2 is connected to a vacuum pump (not shown) for evacuating the inside of the heating chamber 2.
Similarly, the intermediate transfer chamber 1 and the cooling chamber 3 are connected to a vacuum pump (not shown) so that the inside can be evacuated, and the atmosphere is connected to a gas supply device (not shown). For example, nitrogen gas is supplied as the forming gas.

  The cooling chamber 3 is a cylindrical chamber that performs a quenching process by cooling the workpiece X heated in the heating chamber 2 to a predetermined temperature, and is connected below the central chamber 1a of the intermediate transfer chamber 1 as described above. Has been. In the cooling chamber 3, a cooling medium supply device (cooling medium supply unit, mist cooling unit) 16 for supplying a cooling medium is installed. The cooling medium supply device 16 has a plurality of nozzles 17 that inject the cooling medium into the cooling chamber 3 in a mist form. The nozzles 17 are equally disposed at predetermined intervals in the circumferential direction of the side surface of the cylindrical cooling chamber 3 and are also disposed above and below the cooling chamber 3. A large amount of cooling medium can be supplied from the nozzle 17 at a maximum of 1000 liters / minute, for example.

  Further, the cooling medium supply device 16 supplies the header pipe 18 with the cooling medium stored in the cooling medium tank (drainage tank) 22 and a plurality of branched header pipes 18 that guide the cooling medium as mist to the nozzles 17. A cooling medium pump 19 for pumping and a heat exchanger 20 for cooling the cooling medium pumped by the cooling medium pump 19 are provided. The cooling medium supply device 16 of the present embodiment is configured to supply water as a cooling medium. As the cooling medium, for example, oil, salt liquid, fluorine-based inert liquid, or the like can be used in addition to water.

  In the cooling chamber 3, a cooling medium drainage device 21 that drains the cooling medium supplied to the cooling chamber 3 is installed. The cooling medium drainage device 21 includes a cooling medium tank 22 that collects the cooling medium supplied to the cooling chamber 3, a drainage pipe 23 that extracts the cooling medium from the bottom of the cooling chamber 3, and a butterfly that opens and closes the pipeline of the drainage pipe 23. And a valve 24. The cooling medium tank 22 is provided at a position lower than the cooling chamber 3 as shown in FIGS. 1 and 3B. As shown in FIG. 3A, the cooling medium tank 22 is a flat tank, and extends along a horizontal plane at a predetermined height. With this configuration, it is possible to reduce the size of the device without increasing the height of the entire device.

  As shown in FIG. 1, the drain pipe 23 is provided such that one end 23 a communicates with the bottom of the cooling chamber 3 and the other end 23 b communicates with the cooling medium tank 22. The drainage pipe 23 has a sufficiently large diameter (for example, Φ200) so as not to cause pressure loss during drainage of the cooling medium, and connects the cooling chamber 3 and the cooling medium tank 22 in a horizontal posture. It has become. As shown in FIG. 3A, one end portion 23 a of the drain pipe 23 communicates with a drain port 3 a formed at the bottom of the cooling chamber 3. The drain port 3a is formed in a rectangular shape along the extending direction of the drain pipe 23, and ensures a large flow path area.

  As shown in FIG. 3B, the one end portion 23 a of the drain pipe 23 has a shape in which the upper portion is horizontally cut out, and the cooling medium is extracted from the cooling chamber 3 in the radial direction of the drain pipe 23. It has become. On the other hand, the other end 23 b of the drain pipe 23 is connected to the side of the cooling medium tank 22, and the cooling medium is introduced into the cooling medium tank 22 in the length direction (axial direction) of the drain pipe 23. ing.

  As shown in FIG. 1, the butterfly valve 24 is provided in the middle of the drainage pipe 23. In the present embodiment, by adopting the butterfly valve 24, the valve shaft can be rotated 90 degrees to quickly open and close the drain pipe 23, and the pressure loss due to installation can be kept small. Moreover, since the installation width of the butterfly valve 24 can be narrow, the length of the drainage pipe 23 can be shortened compared to other types of valves, and the pressure loss can also be kept small.

  In addition, as shown in FIG. 1, the cooling chamber 3 is provided with a mounting table 25 on which the processing object X can be mounted together with the tray T, and an elevating device (processing object) that can move the mounting table 25 up and down. (Conveyance unit) 26 is installed. The lifting device 26 delivers the workpiece X between the intermediate transfer chamber 1 and the cooling chamber 3 when the above-described upper lid 6 is opened. It can be raised to the inside of the central chamber 1a. As described above, in the present embodiment, the intermediate transfer chamber 1 is connected above the cooling chamber 3, and further, the heating chamber 2 is connected above the intermediate transfer chamber 1, and between the cooling chamber 3 and the intermediate transfer chamber 1. In addition, the workpiece X is delivered between the heating chamber 2 and the intermediate transfer chamber 1 using the lifting devices 9 and 26.

  Next, a characteristic heat treatment operation (heat treatment method) in the multi-chamber heat treatment apparatus S of the present embodiment configured as described above will be described with reference to FIGS. The multi-chamber heat treatment apparatus S of the present embodiment includes a control device (not shown), and the following operations are mainly performed by the control device. Moreover, in the following description, the quenching process which transforms the to-be-processed object X hold | maintained at quenching temperature into the state of a martensitic structure is demonstrated.

  FIG. 4 is a flowchart showing the heat treatment operation of the multi-chamber heat treatment apparatus S in the first embodiment of the present invention. 5 and 6 are views for explaining the heat treatment operation in the first embodiment of the present invention. FIG. 7 is a graph showing a temperature change of the workpiece X by the heat treatment operation in the first embodiment of the present invention. In FIG. 7, the vertical axis represents temperature, and the horizontal axis represents time. In FIG. 7, the solid line indicates the temperature change on the outer surface of the workpiece X, and the broken line indicates the temperature change inside the workpiece X.

  First, the carry-in / out door 4 provided on the side wall of the central chamber 1a of the intermediate transfer chamber 1 shown in FIG. 2 is opened, and the workpiece X placed on the tray T is placed in the central chamber 1a of the intermediate transfer chamber 1. Carry in. Thereafter, the carry-in / out door 4 is closed, the intermediate transfer chamber 1 is evacuated by a vacuum pump (not shown), and when the predetermined vacuum degree is reached, the workpiece X is transferred to the predetermined heating chamber 2. Is done. Specifically, the workpiece X is pushed out together with the tray T by the push device 5 and transported to the heating lift chamber 1b, and then lifted by the lift device 9, whereby the workpiece X on the mounting table 10 is moved. It is conveyed to the heating chamber 2 (see FIG. 1).

  The heating chamber 2 is evacuated in advance by a vacuum pump (not shown). When the workpiece X is carried into the heating chamber 2 by the elevating device 9, the heater 13 and the fan 15 are driven to form a vacuum or atmosphere. The workpiece X is heat-treated in the gas. In the heat treatment, the workpiece X is heated (about 1000 ° C.) to the austenite structure. When the heat treatment in the heating chamber 2 is completed, the workpiece X accommodated in the heating chamber 2 is lowered again by the lifting device 9 to the heating lifting chamber 1b of the intermediate transfer chamber 1. And the to-be-processed object X lowered | hung to the heating raising / lowering chamber 1b is conveyed by the push apparatus 5 to the center of the central chamber 1a with the tray T. FIG.

  In the intermediate transfer chamber 1, before the workpiece X is delivered from the heating chamber 2, the upper lid 6 is raised by the upper lid lifting / lowering device 7, and further lifted by the lifting / lowering device 26 to the opening 1 a 1 opened thereby. The placed mounting table 25 is arranged. For this reason, the to-be-processed object X lowered | hung to the heating raising / lowering chamber 1b will be conveyed on the mounting base 25 by being conveyed to the center of the center chamber 1a.

In the cooling chamber 3, the cooling medium is stored before the workpiece X is transported to the mounting table 25 (step S <b> 1).
The cooling chamber 3 is previously evacuated by a vacuum pump (not shown). Then, the cooling medium supply device 16 is driven in a state where the butterfly valve 24 is closed, and the cooling medium is supplied to the cooling chamber 3 from the plurality of nozzles 17 at a maximum flow rate (1000 liters / minute), for example. 3 can store the cooling medium in a short time.

When the cooling medium is stored in the cooling chamber 3 as described above, the atmosphere forming gas is supplied and the workpiece X is submerged in the cooling medium as shown in FIG. 5A (step S2).
That is, when the workpiece X is transported up to the mounting table 25, the mounting table 25 is lowered by the lifting device 26, and the workpiece X is transported into the cooling chamber 3 and stored in the cooling medium stored in advance. The workpiece X is rapidly cooled (initial cooling) by being submerged in water. In this initial cooling, as shown in FIG. 7, the workpiece X is rapidly cooled to a target temperature Ta so as to avoid a transformation point Ps (so-called pearlite nose) that begins to transform into a pearlite structure.

  In the present embodiment, in the initial cooling (step S2) in which a temperature difference between the inside and outside of the workpiece X is likely to occur, cooling is performed by immersing the workpiece X in a cooling medium instead of mist cooling. Mist cooling is excellent in cooling efficiency and cooling control. However, when the workpiece X is, for example, cylindrical, the area around the mist is reduced on the inside, so that during the initial cooling, The temperature difference may be larger. Therefore, in the present embodiment, in the initial cooling in which the temperature difference between the inside and outside of the workpiece X is likely to occur, the entire surface of the workpiece X is uniformly cooled by immersing the workpiece X in the cooling medium. I have to. For this reason, even if a hole or a groove is formed in the workpiece X, the temperature difference does not increase and the unevenness and bending of the tissue can be suppressed, and the loading amount of the workpiece X can be increased. However, sufficient cooling is possible.

When the workpiece X is submerged in the cooling medium and cooled to the target temperature Ta, the lifting / lowering device 26 pulls up the workpiece X from the cooling medium stored in the cooling chamber 3 as shown in FIG. 5B (step S3). ).
Here, the target temperature Ta is lower than the transformation point Ps (upper transformation point) at which the workpiece X starts to transform into a pearlite structure, and within a range higher than the transformation point Ms at which the workpiece X begins to transform into a martensitic structure. Is set. Specifically, in this embodiment, since the workpiece X is die steel (SKD61), the target temperature Ta is set between 370 ° C and 550 ° C. Note that the target temperature Ta is preferably set to a temperature in the vicinity of the transformation point Ms (a temperature that is higher than the transformation point Ms by about tens of degrees Celsius) in consideration of a process in a mist cooling step described later. The temperature of the workpiece X can be measured by, for example, a non-contact type infrared temperature sensor.

When the workpiece X is pulled up from the cooling medium stored in the cooling chamber 3, as shown in FIG. 6A, the cooling medium stored in the cooling chamber 3 is drained by the cooling medium drainage device 21 (step S4).
Specifically, in the present embodiment, by opening the butterfly valve 24, the cooling chamber 3 and the cooling medium tank 22 are communicated, and the cooling medium stored from the bottom of the cooling chamber 3 with water head pressure is stored in the cooling medium tank 22. Pull out. The drainage pipe 23 has a sufficient diameter and communicates with the drainage port 3a that opens greatly at the bottom of the cooling chamber 3, so that the pressure loss is small and a large amount of cooling medium can be drained in a short time. Can do. Even when it takes a long time to drain the cooling medium stored in the cooling chamber 3, the workpiece X is lifted up in advance by the lifting device 26 in step S3 without waiting for the drainage to be completed. Is partially immersed in the cooling medium, and the temperature difference between the upper and lower surfaces of the workpiece X can be made difficult to occur.

  As shown in FIG. 7, the workpiece X is in the cooling intermediate stop state from step S3 to step S6 described later. In the cooling intermediate stop state, an increase in the temperature difference between the inside and outside of the workpiece X is suppressed, the temperature difference is relaxed by heat conduction inside and outside the workpiece X, and the temperature of the workpiece X is made substantially uniform. it can. The cooling intermediate stop is performed until the temperature difference between the inside and outside of the workpiece X falls within a predetermined threshold (for example, 10 ° C.). In the cooling intermediate stop, when the temperature difference between the inside and outside of the object to be processed X is predicted to be within a predetermined threshold from the temperature difference between the inside and outside of the object to be processed X and the heat transfer coefficient, It is also possible to use a method that ends.

When drainage of the cooling medium stored in the cooling chamber 3 is completed, as shown in FIG. 6B, the workpiece X is lowered to the cooling chamber 3 by the lifting device 26, and the workpiece X is cooled by the cooling medium supply device 16. The mist is cooled (step S5, step S6).
Specifically, when the cooling medium is sprayed from the nozzle 17 into the cooling chamber 3 by the cooling medium supply device 16, the cooling chamber 3 is filled with mist. Then, the cooling medium supplied in a mist form adheres to the workpiece X, and the workpiece X is cooled by the latent heat of the mist. In addition, while the cooling process of the workpiece X is performed in the cooling chamber 3, the upper lid 6 is closed and the cooling chamber 3 is sealed. For this reason, while the workpiece X is cooled in the cooling chamber 3, another workpiece X can be carried into the vacant heating chamber 2.

In step S6, as shown in FIG. 7, the workpiece X is cooled to a temperature not higher than the transformation point Ms. In step S6, the workpiece X in which the temperature difference between the inside and outside is relaxed through steps S3 to S5 is finally cooled to the transformation point Ms or less by mist cooling excellent in cooling efficiency and cooling controllability. As a result, the inner and outer structures of the workpiece X are transformed into a martensite structure almost simultaneously. For this reason, it becomes possible to suppress the temperature difference between the inside and outside of the workpiece X minutely, and it is possible to improve the quality.
Thereafter, the upper lid 6 is lifted by the upper lid lifting device 7 and the placing table 25 is lifted into the intermediate transfer chamber 1 by the lifting device 26, whereby the workpiece X that has been quenched is transferred to the intermediate transfer chamber 1. Then, the workpiece X is carried out from the carry-in / out door 4 to the outside of the multi-chamber heat treatment apparatus S of the present embodiment.

As described above, according to the above-described embodiment, the cooling chamber 3 that can store the workpiece X, the cooling medium supply device 16 that stores the cooling medium in the cooling chamber 3, and the workpiece to be stored in the stored cooling medium. The elevating device 26 for submerging X, the cooling medium draining device 21 for draining the cooling medium stored in the cooling chamber 3 after sinking, and supplying the mist cooling medium to the workpiece X after draining to cool the mist. By adopting the multi-chamber heat treatment device S having the cooling medium supply device 16, in the initial cooling in which the temperature difference between the inside and outside of the workpiece X is likely to occur, the workpiece X is soaked in the cooling medium and processed. By uniformly cooling the entire outer surface of the object X, even if holes or grooves are formed in the object to be processed X, it is possible to suppress unevenness and bending of the structure without causing a temperature difference, Sufficient cooling is possible even if the loading amount of workpiece X is increased To become.
Therefore, in this embodiment, non-uniformity and bending of the tissue can be suppressed regardless of the shape of the workpiece X, and the amount of the workpiece X can be increased.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 8 is a view for explaining the heat treatment operation in the second embodiment of the present invention.
The second embodiment is different from the above-described embodiment in that the lifting device 26 pulls up the workpiece X from the cooling medium stored in the cooling chamber 3 during drainage of the cooling medium after the workpiece X is submerged.

  In the above-described embodiment, the workpiece X is pulled up in advance without waiting for the drainage to be completed by the elevating device 26, but there is an upper limit in the ascending speed for the placement stability of the workpiece X. Then, when pulling up from the cooling medium, there is a predetermined time in which the workpiece X is partially immersed in the cooling medium (a state where the upper part is above the liquid level and the lower part is below the liquid level), and this time is long. And a temperature difference between the upper and lower surfaces of the workpiece X may occur.

  For this reason, in the second embodiment, during the drainage of the cooling medium, the workpiece X is pulled up from the cooling medium stored in the cooling chamber 3, the liquid level of the cooling medium is reduced by the drainage, and By pulling up the workpiece X, the workpiece X is allowed to escape from the cooling medium relatively quickly. As a result, the time during which the workpiece X is partially immersed in the cooling medium can be shortened, and the temperature difference between the upper and lower sides of the workpiece X can be suppressed to a small level, thereby further improving the quality. Become.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 9 is a view for explaining the heat treatment operation in the third embodiment of the present invention.
The third embodiment is different from the above-described embodiment in that a cooling medium stirring device (cooling medium stirring unit) 27 that stirs the cooling medium stored in the cooling chamber 3 is provided.

  The cooling medium agitating device 27 imparts a vertical flow to the cooling medium stored in the cooling chamber 3. The cooling medium agitating device 27 agitates the cooling medium stored in the cooling chamber 3 by spraying the cooling medium through the nozzles 17 of the cooling medium supply device 16 provided at the bottom of the cooling chamber 3. It has become. The nozzle 17 is arranged facing vertically upward. The cooling medium agitating device 27 has a cooling medium circulation unit 28 for circulating the cooling medium stored in the cooling chamber 3. The cooling medium circulation unit 28 includes a pump that pumps the cooling medium, one end communicates with the cooling chamber 3, the other end branches and communicates with a plurality of nozzles 17 provided at the bottom of the cooling chamber 3. ing. The tray T and the mounting table 25 are preferably formed in a lattice shape or a slit shape so as not to obstruct the flow of the cooling medium in the vertical direction.

  According to the third embodiment having the above-described configuration, the coolant that has exchanged heat with the workpiece X stays in place by applying a water flow to the coolant stored in the cooling chamber 3 by the coolant stirring device 27. Since it flows without any problems, the cooling efficiency can be increased. For this reason, it is possible to reliably cool the workpiece X to the target temperature Ta so as to avoid the pearlite nose. Moreover, in 3rd Embodiment, when the to-be-processed object X is immersed in the cooling medium stored in the cooling chamber 3, a water flow can be provided to a cooling medium using the nozzle 17 of the cooling medium supply apparatus 16. FIG. Therefore, the equipment cost can be reduced. When the mist is subsequently cooled, the nozzle 17 may be connected to the header pipe 18 by a switching valve (not shown).

  In the third embodiment, the cooling medium agitating device 27 applies a flow in the vertical direction to the cooling medium stored in the cooling chamber 3, thereby effectively circulating the cooling medium along the outer surface of the workpiece X. Can be made. For example, in an agitation method in which a swirling flow is given to the cooling medium using an impeller or the like, the water flow is formed on the outer peripheral side of the cylindrical cooling chamber 3 and is almost effective for the workpiece X disposed in the center. However, since the water flow can be easily formed toward the workpiece X by forming the water flow vertically upward, the cooling efficiency can be increased.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, it has been described that the workpiece X is pulled up from the cooling medium before the drainage is completed after the workpiece X is submerged into the cooling medium. In addition, by opening the butterfly valve 24, the cooling chamber 3 and the cooling medium tank 22 are communicated, and the cooling medium stored with water head pressure from the bottom of the cooling chamber 3 is extracted to the cooling medium tank 22 at a stretch. When the time during which the processed material X is partially immersed in the cooling medium can be shortened, it is not always necessary to pull up the processed material X.

  Further, for example, in the above embodiment, the cooling medium supply unit and the mist cooling unit are the same device (cooling medium supply device 16) in order to reduce the number of parts of the device and reduce the size and cost of the device. However, the present invention is not limited to this, and depending on the performance of the nozzle 17, an apparatus for storing a cooling medium in the cooling chamber 3 and an apparatus for mist cooling the workpiece X are provided. Each may be a separate device.

  Further, for example, in the above-described embodiment, the cooling medium agitating device 27 has been described as jetting the cooling medium from the nozzle 17 provided at the bottom of the cooling chamber 3, but the present invention provides this. For example, the flow may be imparted by jetting a cooling medium from the nozzle 17 provided on the side surface of the cooling chamber 3.

  Further, for example, in the above-described embodiment, the configuration including the intermediate transfer chamber 1 and the heating chamber 2 as the processing chamber other than the cooling chamber 3 has been described, but the present invention is not limited to this, for example, A multi-chamber heat treatment apparatus including only a cooling chamber and a heating chamber as a processing chamber, a multi-chamber heat treatment apparatus including only a cooling chamber and a transfer chamber as a processing chamber, and a multi-room heat treatment apparatus including only a cooling chamber and a plasma processing chamber as processing chambers. It can also be applied to a chamber heat treatment apparatus.

  S: Multi-chamber heat treatment device (heat treatment device), X: workpiece, 3 ... cooling chamber (cooling tank), 16 ... cooling medium supply device (cooling medium supply unit, mist cooling unit), 17 ... nozzle, 21 ... Cooling medium drainage device (cooling medium drainage part), 22 ... Cooling medium tank (drainage tank), 23 ... Drainage pipe, 23a ... One end part, 23b ... Other end part, 24 ... Butterfly valve, 26 ... Lifting device (processed object) Transport unit), 27 ... cooling medium stirring device (cooling medium stirring unit), 28 ... cooling medium circulation unit

Claims (3)

A step of storing a cooling medium for performing initial cooling in a cooling tank capable of accommodating an object to be processed;
Submerging the object to be treated in the stored cooling medium;
Draining the cooling medium stored in the cooling tank after the submergence;
A step of supplying a mist-like cooling medium to the object to be treated and performing re-cooling by mist cooling after the drainage,
The drainage is performed by extracting a cooling medium from the other end of the drainage pipe to a drainage tank provided at a position lower than the cooling tank by opening a drainage pipe having one end communicating with the bottom of the cooling tank. The heat processing method characterized by the above-mentioned. 2. The heat treatment method according to claim 1, further comprising a step of pulling up an object to be treated from a cooling medium stored in the cooling tank after the submergence and before the drainage is completed. The heat treatment method according to claim 2, wherein the object to be treated is pulled up from the cooling medium stored in the cooling tank during the drainage.

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