Heat treatment apparatus and heat treatment method

Abstract

To provide a heat treatment device and a heat treatment method capable of quickly and efficiently performing heat treatment corresponding to a difference in heat treatment temperature conditions for each type of a laminated iron core.SOLUTION: When the control unit 40 acquires a change in the temperature condition of the heat treatment of the laminated iron core 50 prior to the execution of the heat treatment to the laminated iron core 50, first, a temperature adjustment time from the completion of the heat treatment under the old temperature condition to a state in which the heat treatment chamber corresponds to the new temperature condition is calculated. Subsequently, based on the temperature adjustment time, the control unit 40 temporarily stops the insertion of the laminated core 50 into the conveying unit 20 by the core inserting unit 30. As a result, after the heat treatment can be performed under a new temperature condition, the laminated iron core 50 can be quickly carried into the heat treatment chamber and the heat treatment can be performed, a period in which the heat treatment is not performed can be minimized, and the heat treatment corresponding to various temperature conditions can be efficiently performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat treatment apparatus for performing heat treatment such as annealing on a workpiece, and more particularly to a heat treatment apparatus for treating a laminated iron core as a core in a stator or rotor of a rotating electrical machine as a workpiece. [Background technology]

[0002] Laminated cores are generally used as the cores in which coils and permanent magnets are arranged in the stators or rotors of rotating electrical machines such as electric motors and generators. These laminated cores are manufactured by laminating thin core pieces obtained by punching electromagnetic steel sheets or the like.

[0003] Like general metal workpieces that have undergone punching, punched core pieces inevitably develop processing distortion. If cores are manufactured using such punched core pieces as they are, the distortion will have adverse effects. For this reason, a method has been known in the past to anneal laminated cores in order to homogenize the core pieces and remove distortion. An example of a conventional apparatus for carrying out such annealing is disclosed in Japanese Patent Publication No. 7-42508. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 7-42508 Summary of the Invention [Problem to be solved by the invention]

[0005] A conventional apparatus for annealing a laminated core has the configuration shown in the above-mentioned patent document, and sequentially performs each process, including annealing, on the transported laminated core. On the other hand, laminated cores are often manufactured in small quantities in a variety of types using the same equipment, in line with the increasing variety of electric motors and generators in which they are used. In such cases, the laminated cores that are transported sequentially on a transport device for transport to and from each manufacturing process change type every predetermined number. As the type of laminated core changes, the temperature conditions for heat treatment, such as annealing, may also need to be changed.

[0006] Conventionally, when changing the temperature conditions of a heat treatment process, workers prevent the next type of laminated core, which has different temperature conditions, from entering the heat treatment furnace after completing heat treatment such as annealing under the previous temperature conditions. For example, they temporarily stop the loading of laminated cores into the conveying device used for the heat treatment process. At the same time, workers adjust the temperature inside the furnace so that heat treatment can be performed according to the temperature conditions of the next type of laminated core. Naturally, the loading of laminated cores into the furnace must remain suspended until this temperature adjustment is complete.

[0007] Once the temperature has been adjusted and the interior of the heat treatment furnace is in a state that corresponds to the temperature conditions of the next type of laminated iron core, the worker will resume feeding the laminated iron cores into the conveying device so that the next type of laminated iron core, whose temperature conditions have changed, can enter the furnace and be heat treated.

[0008] As described above, conventionally, workers have had to manually change settings related to whether or not laminated cores can be loaded into a heat treatment furnace, adjusting the temperature inside the furnace, etc. This not only takes time and effort, but also creates the risk of operational errors. If an operational error does occur, there is the problem of further losses in time and costs incurred in correcting the error.

[0009] The present invention has been disclosed to solve the above-mentioned problems, and aims to provide a heat treatment apparatus and a heat treatment method that can quickly and efficiently perform heat treatment that corresponds to changes in the temperature conditions for heat treatment for each type of laminated core. [Means for solving the problem]

[0010] The heat treatment device for laminated iron cores disclosed in the present invention is a heat treatment device that performs heat treatment on laminated iron cores, and includes a heat treatment furnace having at least a heat treatment chamber that performs heat treatment on the laminated iron cores according to heat treatment temperature conditions set for each type of laminated iron core, a transport unit that is capable of supporting one or more sets of the laminated iron cores for each of multiple transport blocks arranged in the transport direction and that allows the laminated iron cores to be transported in and out of the heat treatment furnace as each transport block progresses, and a control unit that controls whether or not the laminated iron cores can be loaded into the heat treatment furnace, wherein the control unit obtains the temperature conditions for the heat treatment of the laminated iron cores in the order in which they are loaded into the transport unit, and in a situation in which the temperature conditions change from the temperature conditions of the previous different type of laminated iron core, the control unit suspends the loading of the laminated iron cores after the heat treatment process for the other type of laminated iron core is completed in the heat treatment chamber of the heat treatment furnace until the heat treatment chamber is able to perform heat treatment under the changed temperature conditions.

[0011] According to the present disclosure, when the control unit acquires a change in the temperature conditions for the heat treatment of the laminated core prior to the heat treatment of the laminated core, the control unit temporarily suspends the introduction of the laminated core into the transport unit to prevent the laminated core from entering the temperature adjustment area of ​​the heat treatment chamber after the change in conditions. As a result, once the heat treatment can be performed under the new temperature conditions, the laminated core can be transported into the temperature adjustment area of ​​the heat treatment chamber and heat treated without any problems. In this way, even if the temperature conditions for the heat treatment change, by adjusting the timing of the introduction of the laminated core, the downtime of the equipment when heat treatment is not being performed can be minimized, and heat treatments corresponding to various temperature conditions can be efficiently performed. Furthermore, since the operator does not need to determine whether to introduce the laminated core depending on the progress of adjustments to the heat treatment chamber to accommodate the new temperature conditions, operational errors can be prevented, and time loss and increased costs can be prevented. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a heat treatment apparatus according to an embodiment of the present invention. [Figure 2]Figure 2(A) is an explanatory diagram of the laminated core support state by the transfer section immediately before the type of laminated core being transferred by the heat treatment apparatus according to one embodiment of the present invention is changed to a different type with the same heat treatment temperature conditions. Figure 2(B) is an explanatory diagram of the laminated core transfer state in the transfer section immediately before the type of laminated core being transferred by the heat treatment apparatus according to one embodiment of the present invention is changed to a different type with the same heat treatment temperature conditions. Figure 2(C) is an explanatory diagram of the laminated core being introduced from the core introduction section to the transfer section when the type of laminated core being transferred by the heat treatment apparatus according to one embodiment of the present invention is changed to a different type with the same heat treatment temperature conditions. [Figure 3] Figure 3(A) is an explanatory diagram of the laminated core support state by the transfer section immediately before the type of laminated core being transferred by the heat treatment apparatus according to one embodiment of the present invention is changed to another type with different heat treatment temperature conditions. Figure 3(B) is an explanatory diagram of the laminated core transfer state by the transfer section immediately before the type of laminated core being transferred by the heat treatment apparatus according to one embodiment of the present invention is changed to another type with different heat treatment temperature conditions. Figure 3(C) is an explanatory diagram of the laminated core transfer state by the transfer section when the core input section is not inputting laminated cores in the heat treatment apparatus according to one embodiment of the present invention. [Figure 4] Figure 4(A) is an explanatory diagram showing a state in which the core input section continues to suspend the supply of laminated cores to the transport section immediately before the type of laminated core being transported by the heat treatment apparatus according to one embodiment of the present invention is changed to a different type with different heat treatment temperature conditions. Figure 4(B) is an explanatory diagram showing a state in which the core input section resumes the suspension of laminated core supply as the laminated core is transported by the transport section in the heat treatment apparatus according to one embodiment of the present invention. Figure 4(C) is an explanatory diagram showing a state in which laminated cores are being supplied from the core input section to the transport section when the type of laminated core being transported by the heat treatment apparatus according to one embodiment of the present invention is changed to a different type with different heat treatment temperature conditions. [Figure 5]Fig. 5(A) is an explanatory diagram of the state of laminated cores supported by the transport unit when heat treatment is performed on the last laminated core of the same type in the annealing chamber of a heat treatment apparatus according to one embodiment of the present invention. Fig. 5(B) is an explanatory diagram of a state in which temperature adjustment can be performed in the second area of ​​the annealing chamber when the heat-treated laminated core is carried out from the annealing chamber of a heat treatment apparatus according to one embodiment of the present invention. Fig. 5(C) is an explanatory diagram of the state of laminated cores supported by the transport unit at the time when temperature adjustment in the second area of ​​the annealing chamber of a heat treatment apparatus according to one embodiment of the present invention is completed. DETAILED DESCRIPTION OF THE INVENTION

[0013] A heat treatment device for a laminated core according to one embodiment of the present invention will be described below with reference to Figures 1 to 5. In this embodiment, an example of an apparatus that performs annealing as heat treatment on a laminated core that forms the core of a rotor or stator of a rotating electrical machine will be described.

[0014] In each drawing, the heat treatment apparatus 1 according to this embodiment includes a heat treatment furnace 10, a transport unit 20, an iron core input unit 30, and a control unit 40. Of these, the heat treatment furnace 10 performs heat treatment on the laminated core 50, and the transport unit 20 transports the laminated core 50 intermittently and enables it to be carried in and out of the heat treatment furnace 10. In addition, the iron core insertion section 30 enables the laminated iron core 50 to be inserted into the conveying section 20 every unit time, and the control section 40 controls at least whether or not the iron core insertion section 30 can insert the laminated iron core 50 into the conveying section 30.

[0015] The laminated core 50, which is the target of annealing as a heat treatment by the heat treatment apparatus 1 according to this embodiment, is configured by stacking a plurality of thin plate-shaped core pieces made of a magnetic metal material. The core pieces that make up the laminated core 50 are formed by punching out thin plate material made of electromagnetic steel, amorphous alloy, or the like by press working. This laminated core 50 has a known structure that forms the core of the stator or rotor of a rotating electrical machine (electric motor or generator), and a detailed description thereof will be omitted.

[0016] The laminated cores 50 are placed one or more times on trays 60, which serve as transport jigs, and the trays 60 are then loaded into the transport section 20 by the core loading section 30. The laminated cores 50, together with the trays 60 on which they are placed, are transported by the transport section 20 and pass through the interior of the heat treatment furnace 10, where they are subjected to heat treatment.

[0017] The laminated core 50 may be placed in the conveying section 20 by the core input section 30, with another tray 60 carrying laminated cores 50 stacked one or more levels on top of the tray 60 on which it is placed, and then conveyed by the conveying section 20.

[0018] The heat treatment furnace 10 has at least an annealing chamber 12 as a heat treatment chamber in which the heat treatment (annealing) of the laminated core 50 is carried out according to the temperature conditions of the heat treatment set for each type of laminated core 50.

[0019] In addition, the heat treatment furnace 10 has a burn-off chamber 11, located upstream of the annealing chamber 12, which performs burn-off (degreasing by combustion) on the laminated core 50. Furthermore, the heat treatment furnace 10 has an annealing chamber 13, located downstream of the annealing chamber 12, which cools the annealed laminated core 50. The heat treatment furnace 10 has a configuration in which a burn-off chamber 11, an annealing chamber 12, and an annealing chamber 13 are arranged in series along the conveying direction of a conveying section 20.

[0020] In the heat treatment furnace 10, openings through which the transported laminated core 50 passes are provided at the boundary between the burn-off chamber 11 and the outside, the boundary between the slow cooling chamber 13 and the outside, the boundary between the burn-off chamber 11 and the annealing chamber 12, and the boundary between the annealing chamber 12 and the slow cooling chamber 13. These openings are provided with shutters (not shown) that are open when the laminated core 50 is being transported per unit time and are closed otherwise, isolating each chamber from the outside or other chambers.

[0021] The shutter is a known device that is opened and closed by an opening and closing mechanism such as an air cylinder in synchronization with the intermittent transport of the laminated core 50 by the transport unit 20 per unit time, and a detailed description thereof will be omitted.

[0022] The burn-off chamber 11 performs so-called burn-off, which removes oils such as stamping oil adhering to the core pieces during the punching process of the core pieces that make up the laminated core 50. The burn-off chamber 11 has a known configuration that includes a gas supply mechanism that supplies an inert gas (e.g., nitrogen gas) into the chamber, an exhaust mechanism that exhausts the atmosphere inside the chamber to the outside, and a heat source such as a heater that heats the laminated core 50 to a temperature at which burn-off is possible, so a detailed description will be omitted.

[0023] In the burn-off chamber 11, the laminated core 50 is heated in an inert gas atmosphere, and oil adhering to the laminated core 50 is removed by evaporation, combustion, etc. Then, nitrogen gas containing oil vapor and combustion gas is discharged to the outside by a discharge mechanism.

[0024] The annealing chamber 12 is a heat treatment chamber of the heat treatment furnace 10, and is provided downstream of the burn-off chamber 11. The annealing chamber 12 performs annealing as a heat treatment on the laminated cores 50 that have left the burn-off chamber 11 in accordance with the temperature conditions for the heat treatment for each type of laminated core 50.

[0025] The annealing chamber 12 is provided with a heat source such as a heater that heats the laminated core 50 to the annealing temperature (for example, near 800°C) and maintains that temperature. The annealing chamber 12 may also be provided with a gas supply mechanism that supplies an inert gas into the chamber and an exhaust mechanism that exhausts the atmosphere inside the chamber to the outside. In this case, the heat source, gas supply mechanism, and exhaust mechanism in the annealing chamber 12 are similar to mechanisms provided in known annealing furnaces, and detailed description thereof will be omitted.

[0026] The annealing chamber 12 is capable of performing temperature control for the heat treatment (annealing) of the laminated cores 50 in two stages using two regions (a first region 12a and a second region 12b) that are separated in the transport direction of the transport section 20. Of the multiple regions in the annealing chamber 12, the second region 12b, which is responsible for the final stage of the heat treatment, is the target of the temperature conditions for the heat treatment. In other words, in the second region 12b, the heat treatment (annealing) of the laminated cores 50 supported by the two transport blocks 21 present in this region is performed in accordance with the temperature conditions.

[0027] As a result, the first region 12a, which is the previous stage to the second region 12b in the final stage, can be set to a state in which the temperature is maintained constant regardless of changes in the temperature conditions for each type of laminated core 50. In this case, the laminated cores 50 can be sequentially stored in the first region 12a for a certain period of time and temperature-controlled while preparing for progression to the second region 12b in the final stage.

[0028] The timing of introducing the laminated core 50 may be set so that, when the temperature adjustment corresponding to the temperature conditions is completed in the second region 12b, the laminated core 50 is preheated to a temperature close to the temperature corresponding to the temperature conditions in the previous first region 12a and is ready to be transferred. This allows for a prompt transition to annealing. In other words, the time required for annealing in the annealing chamber 12 as a heat treatment chamber as a whole can be shortened, and annealing can be carried out efficiently.

[0029] A shutter may be provided between the first region 12a and the second region 12b of the annealing chamber 12, similar to the boundary between the chambers of the heat treatment furnace 10. This shutter is also open to allow the laminated cores 50 to pass through when the laminated cores 50 are transported per unit time, and is closed otherwise to separate the first region 12a from the second region 12b.

[0030] The slow cooling chamber 13 is provided downstream of the annealing chamber 12 and serves to cool the annealed laminated core 50 that has left the annealing chamber 12 down to a temperature at which it is safe to expose it to air. The slow cooling chamber 13 has a known configuration including a supply mechanism that supplies an inert gas such as nitrogen gas as an atmosphere into the chamber, an exhaust mechanism that exhausts the atmosphere inside the chamber to the outside, and a cooling mechanism that exchanges heat between the outside air and the atmosphere inside the chamber to cool the atmosphere, and a detailed description thereof will be omitted. The slow-cooling chamber 13 has a mechanism for slowly cooling the atmosphere in the slow-cooling chamber 13 by using a cooling mechanism, thereby slowly cooling the laminated core 50 in contact with the atmosphere.

[0031] The transport unit 20 is a device that transports the laminated core 50, and transports the laminated core 50 into and out of the heat treatment furnace 10. Specifically, the transport unit 20 is configured as a chain conveyor that includes a pair of endless chains that are stretched in parallel between the drive and driven sprockets, and a large number of plate-shaped slats that are arranged side by side in the chain running direction between the pair of endless chains.

[0032] The conveying section 20 has a known mechanism in which the drive sprocket is driven by an electric motor and a pair of endless chains are moved in a circular motion intermittently, thereby advancing the slats between the endless chains and conveying the transported object placed on the slats, and detailed explanation will be omitted.

[0033] The transport section 20 is installed in parallel with the burn-off chamber 11, the annealing chamber 12, and the slow cooling chamber 13 that make up the heat treatment furnace 10, passing through the interiors of these chambers, so that the transported laminated core 50 remains in each chamber for a predetermined time.

[0034] The transport unit 20 has a plurality of transport blocks 21 set in the transport direction as areas spanning a plurality of lined-up slats, and each of the plurality of transport blocks 21 lined up in the transport direction is capable of supporting a tray 60 and a laminated core 50 placed thereon. The transport unit 20 moves the transport block 21 forward by one block per unit time to transport the laminated core 50 intermittently, thereby enabling the laminated core 50 to be carried in and out of the heat treatment furnace 10. The conveying unit is not limited to a chain conveyor, but may be another conveying device such as a roller conveyor.

[0035] The conveying section 20 is configured so that the conveying block 21 overlaps with a loading position 25 for the laminated cores 50, which is set upstream of the heat treatment furnace 10 in the conveying direction, and stops at this position every unit time. The core loading section 30 loads the laminated cores 50 and trays 60 onto the conveying block 21 that overlaps this loading position 25, making it possible for each conveying block 21 to support the laminated cores 50 and trays 60.

[0036] The transport section 20 is also provided so that one or more transport blocks 21 appear downstream of the heat treatment furnace 10 in the transport direction. From the transport block 21 downstream of the heat treatment furnace 10, the laminated cores 50 and trays 60 are removed by a predetermined removal device (not shown) and sent to a subsequent process.

[0037] The core insertion unit 30 is capable of inserting laminated cores 50 into the transport block 21 per unit time at the insertion position of the transport unit 20. Specifically, the core insertion unit 30 is a device that holds one or more sets of laminated cores 50 placed on trays 60, transports the trays 60 together, and inserts the laminated cores 50 and trays 60 into the transport block 21 of the transport unit 20.

[0038] The core insertion section 30 is a well-known picking robot device that removes the laminated cores 50 together with the trays 60 from a space where the laminated cores 50 are temporarily placed on the trays 60, transports them, and inserts them into the conveying block 21 of the conveying section 20, and detailed explanation will be omitted.

[0039] The tray 60 that the iron core feed unit 30 feeds into the transport unit 20 together with the laminated iron cores 50 has information recorded thereon that is readable from the outside, at least about the type of the laminated iron cores 50 on the tray 60. The information is recorded on the tray 60 by, for example, providing a recording medium such as a barcode (one-dimensional or two-dimensional) or an RFID tag on the surface, such as the side surface.

[0040] The iron core insertion section 30 is configured to include a reading means 31 for reading the information recorded on the tray 60. The reading means 31 of the core feeding section 30 reads the information recorded on the tray 60 just before the tray 60 on which the laminated core 50 is placed is carried out by the core feeding section 30 toward the conveying section 20. Therefore, the information on the type of laminated core 50 is read by the reading means 31 in the order in which the laminated core 50 and tray 60 are fed into the conveying section 20, and is transmitted to the control section 40.

[0041] When the reading means 31 of the core insertion unit 30 reads the information about the type of laminated core 50 recorded on the tray 60, the control unit 40 acquires the temperature conditions for heat treatment corresponding to the type based on this type information. If the type of laminated core 50 that the core insertion unit 30 is about to insert changes and the temperature conditions for heat treatment of the laminated core 50 also change, the control unit 40 can grasp this situation simply by reading the information on the tray 60 with the reading means 31 of the core insertion unit 30.

[0042] In addition, when the control unit 40 acquires the temperature conditions for each type of laminated core 50 and detects changes in the conditions, it is no longer necessary for the operator to directly input the temperature conditions or information such as the type required to acquire the temperature conditions into the control unit 40. This eliminates the possibility of operational errors.

[0043] The control unit 40 controls whether or not the iron core insertion unit 30 can insert the laminated iron core 50 into the transfer block 21 of the transfer unit 20 based on the temperature adjustment time of the annealing chamber 12 in the heat treatment furnace 10.

[0044] The control unit 40 receives information on the type of laminated core 50 read from the tray 60 by the reading means 31 of the core insertion unit 30. The reading means 31 reads information from the tray 60 in the order in which the laminated cores 50 and trays 60 are inserted into the transport unit 20, so the control unit 40 also receives information on the type of laminated core 50 in the order in which they are inserted into the transport unit 20.

[0045] The control unit 40 is provided with a database that records the temperature conditions for heat treatment corresponding to the type of laminated core 50, or can access it via a network. Using this database, the control unit 40 acquires the temperature conditions for heat treatment of the laminated cores 50 corresponding to the type from the received information on the type of laminated core 50, in the order in which they are placed into the transport unit 20. The information on the temperature conditions for heat treatment for each type of laminated core 50 acquired by the control unit 40 is also sent from the control unit 40 to the heat treatment furnace 10, where it is used to set and adjust the heat treatment environment.

[0046] When the type of laminated core 50 that the core feed unit 30 is about to feed is switched to another type, either the temperature conditions for the heat treatment of the laminated core 50 remain unchanged, or the temperature conditions change to different ones in accordance with the type change. The control content of the control unit 40 also differs in these two cases.

[0047] In the latter case, the temperature conditions for the heat treatment of the laminated cores 50 acquired by the control unit 40 in the order of insertion into the transport unit 20 will change from the temperature conditions for the laminated cores of another type immediately before them. In such a situation, the control unit 40 performs control to calculate the temperature adjustment time.

[0048] In detail, the control unit 40 performs control to calculate in advance the temperature adjustment time from the completion of the annealing process under the temperature conditions of the laminated iron core 50 of a different type in the annealing chamber 12 of the heat treatment furnace 10 until the annealing chamber 12 becomes capable of performing annealing under the changed temperature conditions.

[0049] In addition, the control unit 40 sets one or more transport blocks 22 that cannot be loaded after the transport block 21 of the transport unit 20 into which the other type of laminated core 50 is last loaded. Then, the control unit 40 suspends the loading of laminated cores 50 whose temperature conditions have changed by the core loading unit 30 into the set number of transport blocks 22 that cannot be loaded.

[0050] The number of transport blocks 22 that cannot be inserted, set by the control unit 40, is the sum of the following two numbers. One is a number corresponding to an integer obtained by rounding up the value obtained by dividing the temperature adjustment time by the unit time. The other is the number of transport blocks 21 that can fit in the target area (second area 12b) to which the temperature conditions of the heat treatment are applied within the annealing chamber 12.

[0051] In this way, the control unit 40 receives the information recorded on the tray 60 through the reading means 31 of the iron core input unit 30, and based on this information, sequentially obtains the temperature conditions for the heat treatment of the laminated iron core 50, making it possible to grasp the situation in which both the type and temperature conditions of the laminated iron core 50 have changed since just before.

[0052] As a result, when controlling whether or not the core insertion unit 30 can insert the laminated core 50 into the transport unit 20, it is not necessary to directly input the temperature conditions for heat treatment for each type of laminated core 50, or to input information such as the type of laminated core 50 required to obtain the temperature conditions, into the control unit 40. In other words, it is possible to eliminate the possibility of operational errors.

[0053] Furthermore, in a situation where the acquired temperature conditions for the heat treatment of the laminated core 50 change from the temperature conditions for another type of laminated core immediately before that, the control unit 40 not only calculates the temperature adjustment time but also sends information about the temperature conditions to the heat treatment furnace 10. As a result, the heat treatment furnace 10 can perform temperature adjustment to perform heat treatment (annealing) on ​​the laminated core 50 in the annealing chamber 12 that matches the temperature conditions for the heat treatment of the laminated core 50 before the laminated core 50 whose temperature conditions have changed reaches the second region 12b of the annealing chamber 12.

[0054] That is, the heat treatment of the laminated core 50 can be performed after the annealing chamber 12 has been adjusted in advance to match the new temperature conditions for heat treatment sent from the control unit 40. In this case, when adjusting the annealing chamber 12 of the heat treatment furnace 10 to match the temperature conditions for each type of laminated core 50, there is no need to input the temperature conditions directly or the information required to acquire the temperature conditions into the heat treatment furnace 10, which eliminates the possibility of operational errors.

[0055] Next, the heat treatment process performed by the heat treatment apparatus according to this embodiment will be described. It is assumed that laminated core 50 has been obtained in advance by a known manufacturing method, in which multiple core pieces punched from thin sheet material are laminated together. Laminated core 50 is then placed on tray 60 and temporarily placed in a space near core insertion section 30, waiting for core insertion section 30 to insert the entire tray 60 into conveyor section 20.

[0056] When the core insertion unit 30 holds the tray 60 containing the laminated cores 50 and is about to start transporting the tray 60 to the insertion position 25 of the transport unit 20, the reading means 31 reads out the product type information of the laminated cores 50 on the tray 60 that is recorded on the tray 60. The read information is sent to the control unit 40.

[0057] The reading of the information recorded on the tray 60 by this reading means 31 is performed every time the iron core insertion unit 30 attempts to insert a laminated iron core 50 per unit time, and the control unit 40 receives the type information of the laminated iron core 50 in the order of insertion without any omissions.

[0058] Based on the obtained product type information of the laminated core 50, the control unit 40 refers to the database and sequentially acquires the temperature conditions for the heat treatment of the laminated core 50 corresponding to this product type. The control unit 40 then compares the acquired temperature conditions of the laminated core 50 with the temperature conditions of another type of laminated core that was placed just before in the loading order, and if the temperature conditions remain the same, causes the core loading unit 30 to load the laminated core 50 into the transport unit 20. In detail, the control unit 40 controls the core loading unit 30 so that the tray 60 on which the laminated core 50 is placed moves forward by one block per unit time and is loaded into an empty transport block 21 that has reached the loading position 25 of the transport unit 20 (see FIG. 2). In Figures 2 to 5, the upper rows of the rectangular portions shown simplified as laminated core 50 and tray 60, "A," "B," and "C," respectively, represent the types of laminated core, and the lower rows of "1" and "2" represent the temperature conditions of the heat treatment.

[0059] On the other hand, if the acquired temperature conditions of the laminated core 50 have changed to conditions different from the temperature conditions of another type of laminated core that was loaded immediately before in the loading order, the control unit 40 first calculates the temperature adjustment time in the annealing chamber 12 of the heat treatment furnace 10. In detail, the control unit 40 calculates the temperature adjustment time from the completion of the annealing process for the other type of laminated core in the annealing chamber 12 until the annealing chamber 12 becomes ready to perform annealing under the changed temperature conditions. This temperature adjustment time is calculated through processes such as simulating temperature changes due to heating or cooling in the annealing chamber 12 and extracting data that matches the conditions from data acquired and accumulated through temperature adjustments under various actual conditions.

[0060] The control unit 40 calculates the temperature adjustment time for the annealing chamber 12 based on the changed temperature conditions, and then sets the non-insertable transport block 22, which is related to this temperature adjustment time. The non-insertable transport block 22 is set so that the laminated core 50 does not enter the annealing chamber 12, more specifically, the second region 12b of the annealing chamber 12, during the temperature adjustment time.

[0061] The control unit 40 sets one or more of these transport blocks 22 that cannot be loaded following the transport block 21 of the transport unit 20 into which the other type of laminated iron core 50 is last loaded (see FIG. 3). The number of these transport blocks 22 that cannot be loaded is set to the sum of a number equivalent to an integer obtained by rounding up the value obtained by dividing the temperature adjustment time by the unit time, and the number of transport blocks 21 that fit in the second region 12b to which the temperature conditions of the heat treatment (annealing) are applied in the annealing chamber 12. The control unit 40 controls the core insertion unit 30 to stop inserting the laminated cores 50 whose temperature conditions have changed into the set number of transfer blocks 22 that are not allowed to be inserted.

[0062] The control unit 40 continues the suspension of the insertion of laminated cores 50 by the core insertion unit 30 until the progress of the transport blocks 21 in the transport unit 20 per unit time is repeated multiple times and a set number of transport blocks 22 that cannot be inserted pass the insertion position 25 of the transport unit 20. Then, after all of the set number of transport blocks 22 that cannot be inserted have passed the insertion position 25 of the transport unit 20, the control unit 40 causes the core insertion unit 30 to once again insert laminated cores 50 whose temperature conditions have changed into the transport blocks 21 (see FIG. 4).

[0063] As in the case where the temperature conditions do not change, the core insertion section 30 advances one block per unit time and inserts the tray 60 containing the laminated core 50 into an empty conveying block 21 that has reached the insertion position 25 of the conveying section 20.

[0064] After being inserted by the iron core insertion section 30, the laminated iron core 50 and the tray 60 carrying it are supported by the conveying section 20, and as the conveying block 21 of the conveying section 20 moves forward by one block per unit time, the laminated iron core 50 and the tray 60 are also conveyed on the conveying section 20.

[0065] When the transported laminated cores 50 and trays 60 reach the burn-off chamber 11 of the heat treatment furnace 10, a shutter disposed at the boundary between the burn-off chamber 11 and the outside opens. At this time, shutters disposed at the boundary between each chamber, the boundary between the annealing chamber 13 and the outside, and between the first region 12a and the second region 12b of the annealing chamber 12 also open at the same time, allowing the transported laminated cores 50 to pass through. When the transport block 21 of the transport unit 20 advances one block and passes the shutter position, and the transport unit 20 transitions to a stopped state, each shutter closes, isolating each chamber from the outside or other chambers.

[0066] When the laminated core 50 enters the burn-off chamber 11, the exhaust mechanism of the burn-off chamber 11 releases the air inside the chamber to the outside, and the gas supply mechanism supplies an inert gas (e.g., nitrogen gas) into the chamber, replacing the atmosphere inside the burn-off chamber 11 with the inert gas. In this inert gas atmosphere inside the burn-off chamber 11, the laminated core 50 is transported by the transport unit 20 at unit time intervals and heated by the heat from the heat source to a temperature at which burn-off is possible, thereby removing oil adhering to the laminated core 50. The inert gas, including the removed oil vapor and combustion gases, is discharged to the outside by the exhaust mechanism.

[0067] When the laminated core 50, from which oil has been removed by burn-off in the burn-off chamber 11, reaches the boundary between the burn-off chamber 11 and the annealing chamber 12 while being transported by the transport unit 20, the shutter at this boundary opens and the laminated core 50 advances to the first region 12a of the annealing chamber 12. When the transport block 21 containing the burned-off laminated core 50 passes the shutter position and the transport unit 20 transitions to a stopped state, the shutter returns to a closed state, isolating the burn-off chamber 11 from the annealing chamber 12.

[0068] When the laminated core 50 enters the first region 12a of the annealing chamber 12, which has been filled with inert gas beforehand, the exhaust mechanism of the annealing chamber 12 expels the inert gas containing impurities that has flowed in from the burn-off chamber to the outside of the chamber. At the same time, the gas supply mechanism supplies inert gas into the chamber, and the atmosphere in the first region 12a is replaced with clean inert gas. In this inert gas atmosphere in the first region 12a, the laminated core 50 is transported by the transport section 20 at unit time intervals, and is heated by the heat of the heat source to a temperature close to the set temperature conditions for the heat treatment as preheating before the heat treatment.

[0069] When the laminated core 50, which has reached an appropriate temperature through preheating in the first region 12a of the annealing chamber 12, reaches the boundary between the first region 12a and the second region 12b of the annealing chamber 12 while being transported by the transport unit 20, the shutter at this boundary opens and the laminated core 50 advances to the second region 12b as it is transported. When the transport block 21 containing the laminated core 50 passes the shutter position and the transport unit 20 transitions to a stopped state, the shutter returns to a closed state, isolating the first region 12a and the second region 12b of the annealing chamber 12.

[0070] When the laminated core 50 enters the second region 12b of the annealing chamber 12, which has been filled with inert gas beforehand, the exhaust mechanism of the annealing chamber 12 discharges the inert gas that may contain impurities that has flowed in from the first region 12a to the outside of the chamber. At the same time, the gas supply mechanism supplies new inert gas into the chamber, and the atmosphere in the second region 12b is replaced with clean inert gas. In this inert gas atmosphere in the second region 12b, the laminated core 50 is transported by the transport section 20 at unit time intervals, and is annealed by the heat from the heat source until the temperature reaches the temperature set in the temperature conditions for heat treatment (annealing).

[0071] After annealing in the second region 12b of the annealing chamber 12 has continued for a preset time, when the laminated core 50 reaches the boundary between the annealing chamber 12 and the annealing chamber 13 while being transported by the transport unit 20, a shutter at this boundary opens and the laminated core 50 advances into the annealing chamber 13. When the transport block 21 containing the annealed laminated core 50 passes the shutter position and the transport unit 20 transitions to a stopped state, the shutter returns to a closed state, isolating the annealing chamber 12 from the annealing chamber 13.

[0072] When the laminated core 50 enters the annealing chamber 13, which is filled with inert gas beforehand, the exhaust mechanism of the annealing chamber 13 discharges high-temperature inert gas that has flowed in from the second region 12b of the annealing chamber 12 or that has been heated by the heat of the laminated core 50 to the outside of the chamber. At the same time, the gas supply mechanism supplies new inert gas into the chamber, and the atmosphere in the annealing chamber 13 is replaced with inert gas at a temperature suitable for annealing. Furthermore, the cooling mechanism of the annealing chamber 13 gradually lowers the temperature of the atmosphere. In this inert gas atmosphere in the annealing chamber 13, the laminated core 50 advances by the transport section 20 at unit time intervals, gradually lowering its temperature by heat absorption by the atmosphere that is at a lower temperature than the laminated core 50.

[0073] Cooling in the annealing chamber 13 continues for a preset time, and once it has reached a temperature that is not problematic, the laminated cores 50 are transported by the transport unit 20 to the boundary between the annealing chamber 13 and the outside, at which point a shutter at this boundary opens, and the laminated cores 50 proceed from the annealing chamber 13 to the outside. When the transport block 21 containing the annealed and annealed laminated cores 50 passes the shutter position and the transport unit 20 transitions to a stopped state, the shutter returns to a closed state, isolating the annealing chamber 13 from the outside.

[0074] The laminated cores 50 carried out from the annealing chamber 13, together with the trays 60 on which they are placed, reach the conveying section 20 located downstream of the annealing chamber 13, i.e., downstream of the heat treatment furnace 10. The laminated cores 50 and trays 60 are finally removed from the conveying section 20 by a predetermined removal device (not shown) and sent to a subsequent process, thereby completing the series of processes related to the heat treatment.

[0075] For laminated iron cores 50 transported by the transport section 20 and loaded into the heat treatment furnace 10, if the temperature conditions for heat treatment acquired by the control section 40 in the order of loading remain the same even if the laminated iron cores 50 are switched to a different type, the loading of the laminated iron cores 50 into the transport section 20 continues. Therefore, one type of laminated core 50 transported by the transport unit 20 and another type of laminated core 50 after the type change are transported consecutively without an empty transport block 21 between them. Furthermore, because the temperature conditions for heat treatment do not change, the two types of laminated cores 50 are handled consecutively in the same way in each chamber of the heat treatment furnace 10.

[0076] On the other hand, if the temperature conditions for the heat treatment acquired in the control unit 40 in the order of input change to different temperature conditions when the laminated iron core 50 is switched to a different type, the input of the laminated iron core 50 into the conveying unit 20 is temporarily suspended due to the setting of the conveying block 22 as not allowing input.

[0077] For this reason, one type of laminated core 50 transported by the transport unit 20 and another type of laminated core 50 after the type change are transported with the same number of empty transport blocks 21 sandwiched between them as the set number of transport blocks 22 that cannot be loaded. In the heat treatment furnace 10, the temperature conditions for heat treatment differ between the two types of laminated cores 50, so that the laminated cores 50 of each type are handled differently in parts of the heat treatment furnace 10.

[0078] In detail, in the heat treatment furnace 10, based on information sent from the control unit 40 about the heat treatment temperature conditions of the laminated iron core 50 after the product type change, which differ from the temperature conditions before the change, the heat treatment (annealing) is performed in the second region 12b of the annealing chamber 12 under these new heat treatment temperature conditions.

[0079] Therefore, when the heat treatment (annealing) of the laminated iron core 50 before the type change is completed in the second region 12b of the annealing chamber 12 in the heat treatment furnace 10 and the laminated iron core 50 is transported from the second region 12b by the transport section 20, the temperature is immediately adjusted to correspond to the laminated iron core 50 after the type change.

[0080] That is, in the second region 12b of the annealing chamber 12, in order to perform heat treatment (annealing) under the temperature conditions for the heat treatment of the laminated core 50 after the product type change, cooling or additional heating is performed as temperature adjustment.

[0081] If the annealing temperature under the temperature conditions after the product type change is lower than that under the temperature conditions before the product type change, the second region 12b of the annealing chamber 12 is cooled to adjust the temperature. For example, the inert gas that forms the atmosphere inside the annealing chamber 12 is supplied at a temperature lower than the annealing temperature under the previous conditions and in a larger amount than during heat treatment. In this case, by increasing the flow rate of the low-temperature inert gas in the second region 12b of the annealing chamber 12, the frequency of removing heat from each part of the second region 12b can be increased, which can efficiently lower the temperature of the second region 12b and promote a transition to a state that is suitable for the temperature conditions.

[0082] Alternatively, the flow of inert gas supplied by the gas supply mechanism into the annealing chamber 12 may come into contact with a heat source such as a heater. In this case, the low-temperature inert gas inside the annealing chamber 12 comes into contact with the heat source and absorbs heat from the heat source, thereby suppressing radiant heat from a heat source with a higher temperature than the other heat sources. This effectively reduces the temperature of the second region 12b of the annealing chamber 12 and promotes a transition to a state suitable for the new temperature conditions.

[0083] In addition, the inert gas that has been circulated in the second region 12b of the annealing chamber 12 and heated may be discharged from the annealing chamber 12 and introduced into the burn-off chamber 11. The exhaust heat from the annealing chamber 12 can be introduced into the burn-off chamber 11 and effectively utilized for preheating, etc., thereby improving the efficiency of the heat treatment furnace 10 as a whole.

[0084] Conversely, if the annealing temperature under the temperature conditions after the product type change is higher than that under the temperature conditions before the product type change, the second region 12b of the annealing chamber 12 is heated to adjust the temperature. Specifically, the atmosphere is further heated by a heat source.

[0085] It takes a time equivalent to the temperature adjustment period determined in advance by the control unit 40 until the second region 12b of the annealing chamber 12 reaches a state where annealing can be performed in accordance with the changed temperature conditions through temperature adjustment. In response to this, the control unit 40 calculates the temperature adjustment time in the second region 12b of the annealing chamber 12 in advance, and by suspending the introduction of the laminated iron core 50 corresponding to this, the laminated iron core 50 is not allowed to enter the second region 12b during the temperature adjustment time, thereby allowing the temperature adjustment to proceed without any problems.

[0086] When the temperature adjustment in the second region 12b of the annealing chamber 12 is completed, that is, when the temperature adjustment time has elapsed, the laminated core 50 after the product type change is transported to the first region 12a of the annealing chamber 12 and is in a state of waiting to be transferred to the second region 12b. Therefore, the laminated core 50 can be immediately advanced to the second region 12b, where the temperature adjustment has been completed and the second region 12b is ready for heat treatment that matches the temperature conditions after the product type change, and heat treatment (annealing) can be performed promptly.

[0087] In this way, in the heat treatment apparatus according to this embodiment, when the control unit 40 acquires a change in the temperature conditions for the heat treatment of the laminated core 50, the control unit 40 first calculates the temperature adjustment time from the completion of the heat treatment under the old temperature conditions until the annealing chamber 12 is adapted to the new temperature conditions. Next, during this temperature adjustment time, the control unit 40 temporarily suspends the core input unit 30 from inputting the laminated core 50 into the transport unit 20 so that the laminated core 50 after the condition change does not enter the second area 12b of the annealing chamber 12. As a result, once the temperature adjustment time has elapsed and heat treatment can be performed under the new temperature conditions, the laminated core 50 can be transported into the second area 12b of the annealing chamber 12, and heat treatment (annealing) of the laminated core 50 can be performed without any problems.

[0088] In this way, even if the temperature conditions for heat treatment change, by appropriately estimating the temperature adjustment time and adjusting the timing of delivery of the laminated iron core 50 based on that, the non-operational period during which the equipment is not heat treated can be minimized, and heat treatment can be carried out efficiently in accordance with various temperature conditions.

[0089] Furthermore, since the worker does not have to decide whether or not to bring in the laminated core 50 depending on the progress of adjustments to adapt the annealing chamber 12 to new temperature conditions, the occurrence of operational errors can be prevented, and time loss and increased costs can be prevented.

[0090] In the heat treatment apparatus according to this embodiment, the tray 60 on which the laminated iron core 50 is placed is configured to record information that can be read from the outside, and this tray 60 is configured to record information about the type of laminated iron core 50 placed thereon, but this is not limited to this. For example, information on the temperature conditions for heat treatment of laminated cores placed on a tray may be recorded on the tray, either alone or together with product type information.

[0091] In this case, the control unit can directly obtain the temperature conditions for the heat treatment of the laminated core from the information read by the reading means of the core feed unit, eliminating the need to create a database in advance that lists the relationship between the type of laminated core and the corresponding temperature conditions for the heat treatment and then refer to that database from the control unit, thereby reducing the cost of the control unit obtaining information on the temperature conditions for the heat treatment of the laminated core.

[0092] Furthermore, in the heat treatment apparatus according to this embodiment, information on the type of laminated cores 50 placed on the tray 60, which is recorded on the tray 60, is read in the order in which they are placed by the reading means 31 of the core feed unit 30. Then, based on this information, the control unit 40 obtains the temperature conditions for the heat treatment of the laminated cores 50 corresponding to the type, and sends the information on the temperature conditions from the control unit 40 to the heat treatment furnace 10, but the configuration is not limited to this.

[0093] For example, a reading device for reading information recorded on a tray may be provided at a location upstream of the heat treatment furnace in the conveying direction of the conveying section, such as the loading position, so that information on the type of laminated core is read in the order of conveyance. The read information may then be sent to the heat treatment furnace, where temperature conditions for the heat treatment of the laminated core are obtained based on the type of laminated core, and the annealing chamber serving as the heat treatment chamber is then set to correspond to these temperature conditions before the heat treatment of the laminated core is carried out.

[0094] This means that when adapting the heat treatment chamber of the heat treatment furnace to the temperature conditions for each type of laminated iron core, there is no need to input the temperature conditions directly or the information necessary to obtain the temperature conditions into the heat treatment furnace, eliminating the possibility of operational errors.

[0095] Furthermore, in the heat treatment apparatus according to this embodiment, the temperature control for the heat treatment of the laminated core 50 in the annealing chamber 12 is performed by dividing the annealing chamber 12 into two regions, the first region 12a and the second region 12b, but this is not limited to this. For example, the temperature control for the heat treatment of the laminated core in the annealing chamber can also be performed by dividing the annealing chamber into multiple regions (more than two). As a more specific example, the first region in the annealing chamber can be further divided into multiple regions, and temperature control for the heat treatment can be performed individually in each of these divided regions. [Explanation of symbols]

[0096] 1. Heat treatment equipment 10 Heat treatment furnace 11 Burn-off Chamber 12 Annealing Room 12a First area 12b Second area 13 Cooling room 20 Conveying section 21, 22 Transport block 25 Input position 30 Core insertion section 31 Reading means 40 Control Unit 50 laminated core 60 trays

Claims

1. In a heat treatment device for performing heat treatment on a laminated iron core, a heat treatment furnace having at least a heat treatment chamber for performing heat treatment of the laminated core in accordance with temperature conditions for heat treatment set for each type of laminated core; a conveying section that can support one or more sets of the laminated cores for each of a plurality of conveying blocks arranged in a conveying direction and that can carry the laminated cores into and out of the heat treatment furnace as each of the conveying blocks moves; a control unit that controls whether or not the laminated iron core is to be introduced into the heat treatment furnace, The control unit acquires the temperature conditions for the heat treatment of the laminated iron cores in the order of their introduction into the transport unit, and in a situation where the temperature conditions change from the temperature conditions of the immediately preceding laminated iron cores of another type, the control unit suspends introduction of the laminated iron cores from the time the process of heat treatment of the laminated iron cores of another type in the heat treatment chamber of the heat treatment furnace is completed until the heat treatment chamber becomes capable of carrying out the heat treatment under the changed temperature conditions. A heat treatment device characterized by the above.

2. 2. The heat treatment apparatus according to claim 1, an iron core input unit capable of inputting the laminated iron core into the conveying block at an input position upstream of the heat treatment furnace in the moving direction of the conveying unit; the transport unit moves each transport block by one block per unit time to transport the laminated core intermittently, When the temperature conditions change from the previous temperature conditions of the other type of laminated iron core, the control unit calculates in advance a temperature adjustment time from the completion of the heat treatment process for the other type of laminated iron core in the heat treatment chamber of the heat treatment furnace until the heat treatment chamber becomes able to perform the heat treatment under the changed temperature conditions, and sets one or more non-feedable transport blocks after the transport block of the transport unit into which the other type of laminated iron core is last fed, and suspends the feeding of laminated iron cores by the iron core feeding unit into the set number of non-feedable transport blocks, The number of transport blocks that cannot be inserted, which is set by the control unit, is a total number obtained by rounding up the value obtained by dividing the temperature adjustment time by the unit time to an integer, and adding the number of transport blocks that fit within an area to which the temperature conditions of the heat treatment are applied in the heat treatment chamber. A heat treatment device characterized by the above.

3. 3. The heat treatment apparatus according to claim 2, the core input unit inputs one or more sets of laminated cores placed on a tray for transport into the transport block of the transport unit together with the tray, and causes each transport block to support the laminated core together with the tray; the tray has information about at least the type of laminated core on the tray recorded thereon in an externally readable manner; the transport unit has a reading means for reading information recorded on the tray, The heat treatment furnace is capable of referencing information relating to the relationship between the type of laminated core and the temperature conditions for heat treatment for each type, which is recorded in advance, and receives information about the laminated cores on the tray through the reading means of the conveying unit, and acquires the temperature conditions for heat treatment of the laminated cores based on the type of laminated core read from the information. A heat treatment device characterized by the above.

4. 3. The heat treatment apparatus according to claim 2, the core input unit inputs one or more sets of laminated cores placed on a tray for transport into the transport block of the transport unit together with the tray, and causes each transport block to support the laminated core together with the tray; the tray has information about at least the type of laminated core on the tray recorded thereon in an externally readable manner; the iron core insertion unit has a reading means for reading information recorded on the tray, The control unit is capable of referring to information about the relationship between the type of laminated core and the temperature conditions for heat treatment for each type, which is recorded in advance, and receives information about the laminated cores on the tray through the reading means of the core input unit, and acquires the temperature conditions for heat treatment for the laminated cores based on the type of laminated core read from the information. A heat treatment device characterized by the above.

5. 2. The heat treatment apparatus according to claim 1, The heat treatment chamber of the heat treatment furnace is capable of performing temperature control related to the heat treatment of the laminated iron core in a plurality of stages in a plurality of separated regions, and the region that is responsible for the final stage of the heat treatment is made the target of application of the temperature conditions of the heat treatment, and the heat treatment of the laminated iron core is performed in the region according to the temperature conditions. A heat treatment device characterized by the above.

6. 2. The heat treatment apparatus according to claim 1, The heat treatment chamber of the heat treatment furnace is configured to be capable of introducing an inert gas as an internal atmosphere, When the temperature conditions of the heat treatment change and the temperature of the heat treatment falls below the temperature conditions before the change, the heat treatment furnace supplies an inert gas, which is greater in amount and at a lower temperature than when the heat treatment was performed before the temperature conditions changed, to the heat treatment chamber within the temperature adjustment time, and circulates the inert gas inside the heat treatment chamber. A heat treatment device characterized by the above.

7. 2. The heat treatment apparatus according to claim 1, the heat treatment chamber of the heat treatment furnace has a heat source for increasing the temperature inside the chamber and is capable of introducing an inert gas as an internal atmosphere; When the temperature conditions of the heat treatment change and the temperature of the heat treatment falls below the temperature conditions before the change, the heat treatment furnace supplies an inert gas having a temperature lower than the temperature of the previous heat treatment to the heat treatment chamber and brings the inert gas flow into contact with the heat source. A heat treatment device characterized by the above.

8. A heat treatment method for performing heat treatment on a laminated core, comprising: a heat treatment furnace for performing heat treatment on the laminated cores, the heat treatment furnace having at least a heat treatment chamber, in which the heat treatment is performed according to temperature conditions for heat treatment set for each type of the laminated cores; a conveying section that can carry the laminated cores into and out of the heat treatment furnace is capable of supporting one or more sets of the laminated cores for each of a plurality of conveying blocks that are arranged in a moving direction, and the laminated cores are conveyed by moving each of the conveying blocks; a control unit that controls at least whether or not the laminated iron cores are to be introduced into the heat treatment furnace, and acquires temperature conditions for the heat treatment of the laminated iron cores in the order of introduction into the transport unit; In a situation where the temperature conditions of the laminated core change from the immediately preceding temperature conditions of another type of laminated core, the control unit suspends the introduction of the laminated core from the time when the heat treatment process for the other type of laminated core is completed in the heat treatment chamber of the heat treatment furnace until the heat treatment chamber becomes capable of carrying out the heat treatment under the changed temperature conditions. A heat treatment method characterized by:

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