Heating furnace, control device, control program, and control method

Abstract

To support a reduction of energy consumption while maintaining production efficiency.SOLUTION: The control device comprises a control unit, an estimation unit, and a determination unit. The control unit controls an operation mode of a heating furnace to either a normal mode or an energy-saving mode. When the operation mode is the energy-saving mode, the estimation unit outputs an estimated value of an inside of a furnace temperature based on a target temperature-falling model. The target temperature-falling model represents an aging of the inside of the furnace temperature when the heating furnace is operated in a target state in the energy-saving mode. When the operation mode is the normal mode, the estimation unit outputs an estimated value of the inside of furnace temperature based on a target rise of temperature model. The target rise of temperature model represents an aging of the inside of the furnace temperature when the heating furnace is operated in the normal mode at a temperature state lower than the target state. The determination unit uses the estimated value to determine information regarding switching of the operation mode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heating furnace, a control device, a control program, and a control method. [Background technology]

[0002] Conventionally, techniques related to reducing energy consumption at product production sites have been proposed. For example, Japanese Patent Publication No. 5077475 (Patent Document 1) discloses a control device for reducing energy consumption of a heating furnace. The control device operates the heating furnace according to a normal mode in order to maintain the heating furnace in a first state for heat-treating an object to be heated. When a predetermined condition is met, the control device controls the heating furnace according to an energy-saving mode that consumes less energy than the normal mode. The control device stores a reference return time, which is the time required to return the heating furnace from a state operating according to the energy-saving mode to the first state. When the remaining time until the timing at which the heating furnace should be returned to the first state becomes equal to or less than the reference return time while the heating furnace is operating in the energy-saving mode, the control device operates the heating furnace according to the normal mode. The reference return time is determined according to the time from the start of the energy-saving mode to the timing at which the heating furnace should be returned to the first state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5077475 Summary of the Invention [Problem to be solved by the invention]

[0004] The timing of switching to the energy-saving mode is generally determined in advance according to a production plan or the like. However, in response to the occurrence of a trouble in a device upstream of the heating furnace, the user may switch the heating furnace to the energy-saving mode at a stage earlier than the predetermined switching timing. Alternatively, the user may switch the heating furnace to the energy-saving mode again at the stage of returning the heating furnace to the first state. In this way, the heating furnace may be switched to the energy-saving mode at an unintended timing.

[0005] In the technology described in Patent Document 1, the control device determines the timing of switching from the energy-saving mode to the normal mode based on the reference return time. If the heating furnace is switched to the energy-saving mode at the unintended timing as described above, even if the heating furnace is switched to the normal mode at the timing determined based on the reference return time, the heating furnace does not return to the first state at the reference return time. This is because the heating furnace was switched to the energy-saving mode at the unintended timing, and therefore the temperature of the heating furnace when switching from the energy-saving mode to the normal mode is lower than expected. This causes the product to stagnate. As a result, the production efficiency of the product decreases.

[0006] The present disclosure has been made in consideration of the above problems, and its purpose is to support the achievement of both a reduction in energy consumption and the maintenance of production efficiency. [Means for solving the problem]

[0007] According to an example of the present disclosure, a control device for controlling a heating furnace includes a control unit, an estimation unit, and a determination unit. The control unit controls an operation mode of the heating furnace to either a first mode or a second mode. The estimation unit outputs an estimate of an inner temperature of the heating furnace. The determination unit uses the estimate to determine information regarding switching of the operation mode. The first mode is a mode in which the heating furnace operates according to a first condition for maintaining the heating furnace in a target state for heat-treating an object to be heated. The second mode is a mode in which the heating furnace operates according to a second condition that consumes less energy than the first condition. The estimation unit outputs an estimate based on a target temperature drop model when the operation mode is controlled so that the heating furnace operates according to the second condition. The target temperature drop model represents a change over time in the inner temperature of the furnace when the heating furnace in the target state is operated according to the second condition. The estimation unit outputs an estimate based on a target temperature rise model when the operation mode is controlled so that the heating furnace operates according to the first condition. The target temperature rise model represents a change over time in the temperature inside the furnace when the heating furnace is operated in a temperature state lower than the target state according to the first condition.

[0008] According to this disclosure, the control device can grasp an estimated value of the temperature inside the heating furnace. As a result, even if the heating furnace is switched to the energy saving mode at an unintended timing, the control device can determine information regarding switching of the operation mode of the heating furnace according to the estimated value. Therefore, the control device can support both reduction of energy consumption in the heating furnace and maintenance of production efficiency.

[0009] In the above disclosure, the information indicates a first timing for switching the operation mode from the second mode to the first mode. The determination unit determines the information such that the furnace is restored to the target state at a second timing for the furnace to be restored to the target state.

[0010] According to this disclosure, the heating furnace can return to a target state at a second timing by switching the operation mode from a second mode to the first mode at a first timing.

[0011] For example, the estimation unit outputs a first estimated value of the furnace temperature at a third timing when the operation mode is switched from the first mode to the second mode. The third timing is before the first timing. The determination unit determines information based on the first estimated value, the second timing, a target temperature drop model, and a target temperature rise model.

[0012] Alternatively, when the operation mode is controlled so that the furnace operates according to the second condition, the determination unit calculates a fourth timing at which the furnace will return to the target state when the operation mode is assumed to be switched from the second mode to the first mode at the present time based on the estimated value and the target heating model. The determination unit determines the present time as the first timing in response to the condition that the time difference between the fourth timing and the second timing is equal to or less than a threshold value being satisfied.

[0013] In the above disclosure, the information indicates a fourth timing at which the furnace will return to the target state when the furnace is assumed to be switched from the second mode to the first mode at the present time. The determination unit determines the information based on the estimated value and the target heating model.

[0014] According to this disclosure, by checking the determined information, the user can recognize the timing at which the furnace will return to the target state if the furnace is currently switched from the second mode to the first mode.

[0015] In the above disclosure, the control unit selects a second condition from among a plurality of temperature drop conditions and selects a first condition from among a plurality of temperature rise conditions. The estimation unit selects a temperature drop model corresponding to the second condition from among a plurality of temperature drop models corresponding to the plurality of temperature drop conditions as a target temperature drop model. Each of the plurality of temperature drop models represents a change over time in the temperature inside the furnace when the heating furnace is operated according to the corresponding temperature drop condition from among the plurality of temperature drop conditions. The estimation unit selects a temperature rise model corresponding to the first condition from among a plurality of temperature rise models corresponding to the plurality of temperature rise conditions as a target temperature rise model. Each of the plurality of temperature rise models represents a change over time in the temperature inside the furnace when the heating furnace is operated according to the corresponding temperature rise condition from among the plurality of temperature rise conditions.

[0016] According to this disclosure, the control device can select, for example, a temperature drop condition and a temperature rise condition suitable for the object to be heated as the second condition and the first condition. The estimation unit can accurately estimate the temperature inside the furnace operating according to the second condition based on the target temperature drop model corresponding to the selected second condition. Similarly, the estimation unit can accurately estimate the temperature inside the furnace operating according to the first condition based on the target temperature rise model corresponding to the selected first condition.

[0017] In the above disclosure, the estimation unit adjusts the estimated value by an adjustment amount output from the trained model by inputting a measured value of the disturbance factor to the trained model. The trained model is generated by machine learning using a training data set indicating a correspondence relationship between an actual value of the disturbance factor and an amount of fluctuation in the furnace temperature due to the influence of the disturbance factor. According to this disclosure, the estimation unit can accurately estimate the furnace temperature of the heating furnace.

[0018] According to another example of the present disclosure, a control program for controlling a furnace causes a computer to execute the following: controlling an operation mode of the furnace to one of a first mode and a second mode; outputting an estimated value of an inside temperature of the furnace; and using the estimated value to determine information regarding switching of the operation mode. The first mode is a mode in which the furnace operates according to a first condition for maintaining the furnace in a target state for heat-treating an object to be heated. The second mode is a mode in which the furnace operates according to a second condition that consumes less energy than the first condition. The outputting includes outputting an estimated value based on a target temperature drop model when the operation mode is controlled so that the furnace operates according to the second condition. The target temperature drop model represents a change over time in the inside temperature of the furnace when the furnace in the target state is operated according to the second condition. The outputting includes outputting an estimated value based on a target temperature rise model when the operation mode is controlled so that the furnace operates according to the first condition. The target temperature rise model represents a change over time in the inside temperature of the furnace when the furnace in a state of a temperature lower than the target state is operated according to the first condition.

[0019] According to yet another example of the present disclosure, a method for controlling a furnace includes controlling an operation mode of the furnace to one of a first mode and a second mode, outputting an estimated value of an inside temperature of the furnace, and using the estimated value to determine information regarding switching of the operation mode. The first mode is a mode in which the furnace operates according to a first condition for maintaining the furnace in a target state for heat-treating an object to be heated. The second mode is a mode in which the furnace operates according to a second condition that consumes less energy than the first condition. The outputting includes outputting an estimated value based on a target temperature drop model when the operation mode is controlled so that the furnace operates according to the second condition. The target temperature drop model represents a change over time in the inside temperature of the furnace when the furnace in the target state is operated according to the second condition. The outputting includes outputting an estimated value based on a target temperature rise model when the operation mode is controlled so that the furnace operates according to the first condition. The target temperature rise model represents a change over time in the inside temperature of the furnace when the furnace in a state of a temperature lower than the target state is operated according to the first condition.

[0020] According to yet another example of the present disclosure, a heating furnace includes the above control device.

[0021] These disclosures also enable the heating furnace, the control program, or the control method to support both reduction in energy consumption and maintenance of production efficiency. Effect of the Invention

[0022] According to the present disclosure, the heating furnace, the control device, the control program, or the control method can assist in achieving both a reduction in energy consumption and the maintenance of production efficiency. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram showing an example of an overall configuration of a production system including a heating furnace according to an embodiment; [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of a reflow furnace. [Diagram 3]2 is a block diagram showing an example of a hardware configuration of a control device according to an embodiment; [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device according to an embodiment. [Diagram 5] FIG. 4 illustrates an example of a configuration of an estimation unit according to an embodiment. [Figure 6] 4 is a flowchart showing a process flow of the control device. [Figure 7] FIG. 13 is a diagram illustrating an example of an operation screen. [Figure 8] 4A and 4B are diagrams illustrating a method for determining a first timing for switching an operation mode from an energy saving mode to a normal mode. [Figure 9] FIG. 1 is a diagram for explaining an example of processing in the prior art when the first example is taken as a premise. [Figure 10] FIG. 11 is a diagram for explaining a second processing example of the control device according to the present embodiment when the first case is assumed. [Figure 11] FIG. 11 is a diagram for explaining an example of control in the conventional technology when the second case is assumed. [Figure 12] FIG. 11 is a diagram illustrating a processing example 3 of the control device according to the present embodiment when the second case is assumed. [Figure 13] FIG. 11 is a diagram for explaining an example of processing by the control device according to the present embodiment when a third case is assumed. [Figure 14] FIG. 13 is a diagram showing an example of a screen displayed on an HMI. [Figure 15] FIG. 11 is a diagram showing another example of a screen displayed on the HMI. [Figure 16] FIG. 11 is a diagram illustrating a fifth processing example of the control device according to the present embodiment. [Figure 17] FIG. 13 is a diagram illustrating an example of the configuration of an estimation unit according to Modification 1. [Figure 18] FIG. 11 is a diagram illustrating a functional configuration of a control device according to a second modified example. [Figure 19] FIG. 11 is a diagram showing a functional configuration of a control device according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and the description thereof will not be repeated. In this specification, unless otherwise specified, the term "or" includes the meaning of "and" in addition to the meaning of "or".

[0025] §1 Examples of application Fig. 1 is a diagram showing an example of the overall configuration of a production system including a heating furnace according to an embodiment. The production system 1 shown in Fig. 1 mounts electronic components on a printed circuit board. The production system 1 includes a reflow furnace 100, which is an example of a heating furnace, and a control device 500 that controls the reflow furnace 100. Furthermore, the production system 1 includes a loader 210, a solder printer 220, an inspection device 230, a high-speed mounter 240, a high-precision mounter 250, an inspection device 260, and an unloader 310.

[0026] The printed circuit board is sent in the following order: loader 210, solder printer 220, inspection device 230, high-speed mounter 240, high-precision mounter 250, inspection device 260, reflow furnace 100, and unloader 310. Arrow D1 in Fig. 1 indicates the transport direction of the printed circuit board.

[0027] The loader 210 transports the printed circuit board to the solder printer 220. The solder printer 220 prints solder on the printed circuit board. The inspection device 230 inspects the printing state. The high-speed mounter 240 and the high-precision mounter 250 mount electronic components on the printed circuit board. The inspection device 260 inspects the mounting state. The printed circuit board on which the electronic components are mounted is transported to the reflow furnace 100. The printed circuit board on which the electronic components are mounted is an example of the "heated object" of the present disclosure. The solder on the printed circuit board melts once while passing through the reflow furnace 100, and then solidifies. As a result, the electronic components are fixed to the printed circuit board. The unloader 310 transports the printed circuit board to various processes.

[0028] The loader 210, the solder printer 220, the inspection device 230, the high-speed mounter 240, the high-precision mounter 250, the inspection device 260, the reflow furnace 100, and the unloader 310 are each provided with an emergency lamp 219, 229, 239, 249, 259, 269, 109, 319. The emergency lamps 219, 229, 239, 249, 259, 269, 109, 319 are controlled to light up when a trouble occurs in the corresponding device. For example, a user can recognize that a trouble has occurred in a device in the previous stage of the reflow furnace 100 by the lighting of the emergency lamps 219, 229, 239, 249, 259, 269.

[0029] The control device 500 controls the reflow furnace 100. The control device 500 is typically a PLC (Programmable Logic Controller). Alternatively, the control device 500 may be an industrial PC (Personal Computer).

[0030] The control device 500 is communicably connected to an HMI (Human Machine Interface) 600. The HMI 600 provides an environment for the user to operate the control device 500. More specifically, the HMI 600 outputs an operation screen for receiving various operations from the user and a screen for displaying various information to be provided to the user.

[0031] As shown in FIG. 1, the control device 500 includes, as its main components, a control unit 51, an estimation unit 52, and a determination unit 53.

[0032] The control unit 51 controls the operation mode of the reflow furnace 100 to either a normal mode or an energy saving mode.

[0033] The normal mode is a mode in which the reflow furnace 100 operates according to a first condition for maintaining the reflow furnace 100 in a target state for heat treating a printed circuit board. The energy saving mode is a mode in which the reflow furnace 100 operates according to a second condition that consumes less energy than the first condition. The normal mode is an example of a "first mode" in the present disclosure. The energy saving mode is an example of a "second mode" in the present disclosure.

[0034] The control unit 51 generates a control signal for switching the operation mode of the reflow furnace 100, and outputs the control signal to the reflow furnace 100. The reflow furnace 100 switches the operation mode in accordance with the control signal.

[0035] The reflow furnace 100 generates a status signal indicating the current operation mode, and outputs the status signal to the control device 500. This allows the control device 500 to recognize the current operation mode of the reflow furnace 100.

[0036] The estimation unit 52 outputs an estimated value of the temperature inside the reflow furnace 100. When the operation mode is controlled so that the reflow furnace 100 operates according to the second condition, the estimation unit 52 outputs the estimated value based on the target temperature drop model. The target temperature drop model represents the change over time in the temperature inside the reflow furnace 100 when the reflow furnace 100 in the target state is operated according to the second condition.

[0037] Furthermore, the estimation unit 52 outputs an estimated value based on the target temperature rise model when the operation mode is controlled so that the reflow furnace 100 operates according to the first condition. The target temperature rise model represents a change over time in the temperature inside the furnace when the reflow furnace 100, which is in a temperature state lower than the target state, is operated according to the first condition.

[0038] The determination unit 53 determines information regarding switching of the operation mode of the reflow furnace 100 using the estimated value output from the estimation unit 52. For example, the information indicates the timing at which the operation mode is switched from the energy-saving mode to the normal mode. Alternatively, the information indicates the timing at which the reflow furnace 100 will return to a target state when it is assumed that the operation mode is switched from the energy-saving mode to the normal mode at the present time.

[0039] According to this embodiment, the control device 500 can grasp an estimated value of the temperature inside the reflow furnace 100. As a result, even if the reflow furnace 100 is switched to the energy-saving mode at an unintended timing, the control device 500 can determine information regarding switching of the operation mode of the reflow furnace 100 according to the estimated value. For example, the control device 500 may determine information indicating the timing of switching the operation mode from the energy-saving mode to the normal mode according to the estimated value. Alternatively, the control device 500 may determine information indicating the timing of returning the reflow furnace 100 to the target state according to the estimated value. The control device 500 may switch the operation mode of the reflow furnace 100 based on the determined information. Alternatively, the control device 500 may provide the determined information to a user and accept an operation from the user. In this way, the control device 500 can support both reduction of energy consumption in the reflow furnace 100 and maintenance of production efficiency.

[0040] §2 Specific examples <Outline of reflow furnace configuration> Fig. 2 is a diagram showing a schematic configuration of a reflow furnace. As shown in Fig. 2, a reflow furnace 100 includes a conveyor 20. The conveyor 20 transports a printed circuit board 2. An arrow D2 in Fig. 2 indicates the rotation direction of the conveyor 20.

[0041] The reflow furnace 100 includes an inert atmosphere chamber 13 and ducts 36A and 36B. The duct 36A is provided on the upstream side of the inert atmosphere chamber 13. The duct 36B is provided on the downstream side of the inert atmosphere chamber 13. The ducts 36A and 36B are provided with fans 30A and 30B and opening / closing plates 32A and 32B, respectively. The fans 30A and 30B are driven by motors 31A and 31B. The motors 31A and 31B receive power from inverters 35A and 35B.

[0042] The opening / closing plates 32A and 32B are provided to adjust the degree of air flow in the ducts 36A and 36B, respectively. The degree of opening and closing of the air passages in the ducts 36A and 36B by the opening / closing plates 32A and 32B is controlled by damper motors 33A and 33B, respectively.

[0043] The conveyor 20 passes through an inert atmosphere chamber 13. When the solder used for the printed circuit board 2 is a so-called lead-free solder, it is desirable that the oxygen concentration in the inert atmosphere chamber 13 is low. In this case, nitrogen gas is sent to the inert atmosphere chamber 13 through a nitrogen line 14 in order to reduce the oxygen concentration. The amount of nitrogen gas introduced into the inert atmosphere chamber 13 is controlled by the opening and closing degree of a nitrogen valve (hereinafter also referred to as an "N2 valve") 16. The reflow furnace 100 has a flowmeter 15 that detects the flow rate of the nitrogen gas in the nitrogen line 14. Furthermore, the reflow furnace 100 has an oxygen concentration sensor (hereinafter also referred to as an "O2 concentration sensor") 21 for detecting the oxygen concentration in the inert atmosphere chamber 13.

[0044] The reflow furnace 100 has seven sets of heating devices, namely, heaters 11A and 11B, heaters 11C and 11D, heaters 11E and 11F, heaters 11G and 11H, heaters 11I and 11J, heaters 11K and 11L, and heaters 11M and 11N, for heating the printed circuit board 2 passing through the inert atmosphere chamber 13. Each set of heating devices includes a heater disposed above and a heater disposed below the conveyor 20. The reflow furnace 100 has a power meter 22 that measures the power consumed by the heaters 11A to 11N.

[0045] The reflow furnace 100 has fans 12A, 12B, fans 12C, 12D, fans 12E, 12F, fans 12G, 12H, fans 12I, 12J, fans 12K, 12L, and fans 12M, 12N in the vicinity of each heater to agitate the air within the inert atmosphere chamber 13.

[0046] In the inert atmosphere chamber 13, the printed circuit board 2 heated by the heaters 11A to 11N is sent to the duct 36B and cooled by the chiller 23. The chiller 23 includes cooling pipes 24 and 25. The cooled printed circuit board 2 is sent to the next process (for example, the unloader 310 in FIG. 1).

[0047] The inert atmosphere chamber 13 and the duct 36B are provided with temperature sensors (not shown). The reflow furnace 100 has a temperature adjustment unit 102 that feedback controls the operation of the heaters 11A-11N based on the temperature detected by the temperature sensor. The reflow furnace 100 also has a controller 101 that controls the overall operation of each element such as the heaters 11A-11N based on the output of the power meter 22 or the oxygen concentration sensor 21. The temperature inside the inert atmosphere chamber 13 is an example of the "furnace temperature" in the present disclosure.

[0048] The controller 101 communicates with the control device 500. The controller 101 switches the operation mode in response to a control signal from the control device 500. When the controller 101 receives an instruction to switch to the normal mode, it controls each part of the reflow furnace 100 to operate according to a first condition. When the controller 101 receives an instruction to switch to the energy saving mode, it controls each part of the reflow furnace 100 to operate according to a second condition. Each of the first condition and the second condition includes a condition indicating a set temperature in the inert atmosphere chamber 13, a condition indicating an amount of nitrogen gas introduced into the inert atmosphere chamber 13, or a condition indicating a degree of opening and closing of the air passages in the ducts 36A and 36B.

[0049] The controller 101 is also communicatively connected to a personal computer (hereinafter also referred to as "PC") 300 that functions as a monitor or the like. The controller 101 may switch the operation mode based on information acquired from the PC 300. This allows a user to operate the PC 300 to forcibly switch the operation mode of the reflow furnace 100.

[0050] The controller 101 outputs a status signal indicating the current operation mode to the control device 500 .

[0051] <Control device hardware configuration> Fig. 3 is a block diagram showing an example of a hardware configuration of a control device according to an embodiment. As shown in Fig. 3, the control device 500 includes a processor 501 such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), a chipset 502, a main memory 503, a storage 504, a control network controller 505, an information network controller 506, a USB controller 507, and a memory card interface 508.

[0052] The processor 501 reads out various programs stored in the storage 504, expands them in the main memory 503, and executes them to realize calculations for controlling the controlled object. The chipset 502 controls data transmission between the processor 501 and each component.

[0053] The storage 504 stores a system program 110 for implementing basic processing, a user program 111 for implementing control calculations, and an information group 512 used for executing the programs. The information group 512 includes the above-mentioned target temperature drop model and target temperature rise model.

[0054] The control network controller 505 controls data exchange with the control targets, including the reflow furnace 100, via the control network.

[0055] The information network controller 506 controls data exchange with external devices (including the HMI 600) via the information network. For example, the information network controller 506 outputs screen data indicating a screen to be displayed on the HMI 600. Furthermore, the information network controller 506 accepts user input from the HMI 600.

[0056] The USB controller 507 controls data exchange with external devices via a USB connection.

[0057] The memory card interface 508 is configured to allow a memory card 520 to be attached / detached. The memory card interface 508 writes data to the memory card 520 and reads various data (such as a user program) from the memory card 520.

[0058] 3 shows a configuration example in which necessary processes are provided by executing a program by the processor 501. However, some or all of the provided processes may be implemented using a dedicated hardware circuit (for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array)).

[0059] <Functional configuration> Fig. 4 is a diagram showing an example of a functional configuration of a control device according to an embodiment. As shown in Fig. 4, the control device 500 includes a storage unit 50, a control unit 51, an estimation unit 52, and a determination unit 53. The storage unit 50 can be realized by the main memory 503 or the storage 504 shown in Fig. 3. The control unit 51, the estimation unit 52, and the determination unit 53 can be realized by the processor 501 executing a program.

[0060] The control unit 51 controls the operation mode of the reflow furnace 100 to either a normal mode or an energy saving mode.

[0061] When the control unit 51 controls the reflow furnace 100 to the energy saving mode, the control unit 51 may select one of the plurality of temperature reduction conditions as the second condition. The plurality of temperature reduction conditions differ from each other, for example, in the set temperature in the inert atmosphere chamber 13, the amount of nitrogen gas introduced into the inert atmosphere chamber 13, or the opening degree of the air passage in the ducts 36A and 36B. The plurality of temperature reduction conditions are determined in advance.

[0062] The control unit 51 may select the second condition from among a plurality of temperature reduction conditions according to the type of the printed circuit board 2 transported in the normal mode before switching to the energy saving mode. For example, when the amount of solder printed on the printed circuit board 2 is relatively large, the control unit 51 selects, as the second condition, a temperature reduction condition in which the opening degree of the air passage in the ducts 36A, 36B is relatively large.

[0063] Furthermore, when the control unit 51 controls the reflow furnace 100 to the normal mode, the control unit 51 may select one of the plurality of temperature rise conditions as the first condition. The plurality of temperature rise conditions differ from each other, for example, in the set temperature in the inert atmosphere chamber 13, the upper limit of the power supply to each heater, the amount of nitrogen gas introduced into the inert atmosphere chamber 13, or the opening degree of the air passage in the ducts 36A and 36B. The plurality of temperature rise conditions are determined in advance.

[0064] The control unit 51 may select the first condition from among a plurality of temperature rise conditions according to the type of the printed circuit board 2 transported in the normal mode. For example, the control unit 51 selects, as the first condition, a temperature rise condition that specifies a set temperature suitable for the melting temperature of the solder printed on the printed circuit board 2. Alternatively, when the solder printed on the printed circuit board 2 is lead-free, the control unit 51 selects, as the first condition, a temperature rise condition in which the amount of nitrogen gas introduced into the inert atmosphere chamber 13 is relatively large. Alternatively, when the amount of solder printed on the printed circuit board 2 is relatively large, the control unit 51 selects, as the first condition, a temperature rise condition in which the opening degree of the air passage in the ducts 36A and 36B is relatively large.

[0065] The estimation unit 52 outputs an estimate of the temperature inside the reflow furnace 100. As described above, the estimation unit 52 outputs an estimate of the temperature inside the reflow furnace 100 based on the target temperature drop model when the operation mode is controlled so that the reflow furnace 100 operates according to the second condition. The estimation unit 52 selects one of the one or more temperature drop models 55 stored in the storage unit 50 as the target temperature drop model.

[0066] When the storage unit 50 stores one temperature drop model 55, the estimation unit 52 may select this one temperature drop model 55 as the target temperature drop model.

[0067] When the storage unit 50 stores a plurality of temperature drop models 55, the estimation unit 52 may select one of the plurality of temperature drop models 55 as a target temperature drop model. Each of the plurality of temperature drop models 55 represents a change over time in the temperature inside the furnace when the reflow furnace 100 is operated according to a corresponding temperature drop condition among the plurality of temperature drop conditions. The estimation unit 52 may select, from the plurality of temperature drop models 55, a temperature drop model corresponding to the second condition selected by the control unit 51 as a target temperature drop model.

[0068] The estimation unit 52 outputs an estimate of the temperature inside the reflow furnace 100 based on the target temperature rise model when the operation mode is controlled so that the reflow furnace 100 operates according to the first condition. The estimation unit 52 selects one of the one or more temperature rise models 56 stored in the storage unit 50 as the target temperature rise model.

[0069] When the storage unit 50 stores one temperature rise model 56, the estimation unit 52 may select this one temperature rise model 56 as the target temperature fall model.

[0070] When the memory unit 50 stores a plurality of temperature rise models 56, the estimation unit 52 may select one of the plurality of temperature rise models 56 as a target temperature rise model. Each of the plurality of temperature rise models 56 represents a change over time in the temperature inside the furnace when the reflow furnace 100 is operated according to a corresponding temperature rise condition among the plurality of temperature rise conditions. The estimation unit 52 may select, from the plurality of temperature rise models 56, a temperature rise model corresponding to the first condition selected by the control unit 51 as a target temperature rise model.

[0071] As described above, the determination unit 53 uses the estimated value output from the estimation unit 52 to determine information regarding switching of the operation mode.

[0072] <Configuration of the estimation unit> Fig. 5 is a diagram showing an example of a configuration of an estimation unit according to an embodiment. As shown in Fig. 5, estimation unit 52 includes calculators 80 and 81, an adder 82, and a delay element 83. Estimation unit 52 outputs an estimate of the temperature inside reflow furnace 100 for each unit time Δt.

[0073] The calculator 80 calculates the previous estimated value T k-1 The function 55A indicates the relationship between time and the temperature inside the furnace. The calculator 80 determines a point Pa' that is a unit time Δt after the point Pa in the function 55A. The calculator 80 calculates the temperature value of the point Pa' by multiplying it by the current estimated value T k The calculator 80 is enabled only when the operation mode of the reflow furnace 100 is the energy saving mode. In other words, the calculator 80 outputs 0 when the operation mode of the reflow furnace 100 is the normal mode. The estimation unit 52 may determine the operation mode of the reflow furnace 100 based on the status signal received from the reflow furnace 100.

[0074] The calculator 81 calculates the previous estimated value T k-1The function 56A indicates the relationship between time and the temperature inside the furnace. The calculator 81 determines a point Pb' that is a unit time Δt after the point Pb. The calculator 81 calculates the temperature value of the point Pb' by multiplying it by the current estimated value T k The calculator 81 is enabled only when the operation mode of the reflow furnace 100 is the normal mode. In other words, the calculator 81 outputs 0 when the operation mode of the reflow furnace 100 is the energy saving mode.

[0075] The adder 82 adds the outputs of the calculators 80 and 81. As described above, when the operation mode of the reflow furnace 100 is the normal mode, the calculator 80 outputs 0. Therefore, when the operation mode of the reflow furnace 100 is the normal mode, the adder 82 adds the estimated value T k When the operation mode of the reflow furnace 100 is the energy saving mode, the calculator 81 outputs 0. Therefore, when the operation mode of the reflow furnace 100 is the energy saving mode, the adder 82 outputs the estimated value T k Output.

[0076] The delay element 83 delays the signal indicating the estimated value output from the adder 82 by a unit time Δt. The output of the delay element 83 is input to the calculators 80 and 81. As a result, the calculators 80 and 81 receive the previous estimated value T k-1 Receive.

[0077] <Processing flow of the control device> Fig. 6 is a flowchart showing the flow of processing by the control device. Steps S1 to S5 shown in Fig. 6 are performed after the start-up operation of the reflow furnace 100. After the start-up operation, the reflow furnace 100 is maintained in a target state for heat-treating the object to be heated.

[0078] In step S1, the processor 501 of the control device 500 determines, based on a status signal from the reflow furnace 100, whether or not the operation mode of the reflow furnace 100 has been switched from the normal mode to the energy saving mode.

[0079] If the operation mode cannot be switched from the normal mode to the energy saving mode (NO in step S1), the process returns to step S1.

[0080] When the operation mode is switched from the normal mode to the energy saving mode (YES in step S1), the process proceeds to step S2. In step S2, the processor 501 outputs an estimate of the temperature inside the reflow furnace 100 based on the target temperature drop model. Note that in the first step S2, the processor 501 outputs the previous estimate T k-1 A temperature in a target state (hereinafter, referred to as a "target temperature TT") may be set as the target temperature.

[0081] In step S3 following step S2, the processor 501 determines information regarding switching of the operation mode of the reflow furnace 100 using the estimated value output in step S2.

[0082] In step S4 following step S3, the processor 501 determines, based on the status signal from the reflow furnace 100, whether or not the operation mode of the reflow furnace 100 has been switched from the energy saving mode to the normal mode.

[0083] If the operation mode cannot be switched from the energy saving mode to the normal mode (NO in step S4), the process returns to step S2, whereby the processor 501 continues to output the current estimate of the temperature inside the reflow furnace 100 operating according to the second condition.

[0084] If the operation mode is switched from the energy saving mode to the normal mode (YES in step S4), the process proceeds to step S5. In step S5, the processor 501 outputs an estimate of the temperature inside the reflow furnace 100 based on the target temperature rise model.

[0085] In step S6 following step S5, the processor 501 uses the estimated value output in step S6 to determine information regarding switching of the operation mode of the reflow furnace 100. Note that step S6 may be omitted.

[0086] In step S7 following step S6, the processor 501 determines, based on the status signal from the reflow furnace 100, whether or not the operation mode of the reflow furnace 100 has been switched back to the energy saving mode from the normal mode.

[0087] If the operation mode is not switched from the normal mode back to the energy saving mode (NO in step S7), the process returns to step S5, whereby the processor 501 continues to output the current estimate of the temperature inside the reflow furnace 100 operating according to the first condition.

[0088] If the operation mode is switched from the normal mode back to the energy saving mode (YES in step S7), the process proceeds to step S2.

[0089] <Example of control device processing> Some operation examples of the control device 500 are described below.

[0090] (Processing example 1) The processing example 1 is an example in which the operation mode of the reflow furnace 100 is switched from the normal mode to the energy saving mode at a predetermined timing.

[0091] FIG. 7 is a diagram showing an example of an operation screen. The screen 60 shown in FIG. 7 is displayed on the HMI 600. The screen 60 includes input fields 61 and 62 for setting each time period during which the reflow furnace 100 does not need to be maintained in the target state. In FIG. 7, only two input fields corresponding to one time period are marked with the symbols "61" and "62". Hereinafter, the time period during which the reflow furnace 100 does not need to be maintained in the target state is referred to as an "idling time period". The idling time period can also be said to be a time period from when the energy saving mode is started until the reflow furnace 100 is restored to the target state again. The idling time period is determined in advance based on a production plan, a working pattern, or the like. The start timing of the idling time period is input in the input field 61. The end timing of the idling time period is input in the input field 62. In other words, the end timing of the idling time period is the start timing of production by the reflow furnace 100.

[0092] The control unit 51 of the control device 500 determines the start timing input in the input field 61 as the timing for switching the operation mode of the reflow furnace 100 from the normal mode to the energy saving mode. The control unit 51 generates a control signal in accordance with the determined timing.

[0093] Furthermore, the determination unit 53 determines information indicating a first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode, using the estimated value output from the estimation unit 52. The determination unit 53 determines the information indicating the first timing such that the reflow furnace 100 returns to the target state at the end timing input in the input field 62.

[0094] FIG. 8 is a diagram for explaining a method for determining a first timing for switching the operation mode from the energy-saving mode to the normal mode. In FIG. 8, timing t1 is a timing inputted into the input field 61 of the screen 60 shown in FIG. 7. Timing t1 is an example of the "third timing" of the present disclosure. Timing t3 is a timing inputted into the input field 62 of the screen 60. Timing t3 is a timing for returning the reflow furnace 100 to the target state, and is an example of the "second timing" of the present disclosure. The determination unit 53 determines the first timing for switching the operation mode of the reflow furnace 100 from the energy-saving mode to the normal mode between timing t1 and timing t3.

[0095] As shown in FIG. 8, the control unit 51 switches the control signal from a low level to a high level at a timing t1. In the example shown in FIG. 8, a high-level control signal means that the operation mode of the reflow furnace 100 is controlled to the energy-saving mode. A low-level control signal means that the operation mode of the reflow furnace 100 is controlled to the normal mode. As a result, the reflow furnace 100 switches the operation mode to the energy-saving mode in accordance with the control signal at a timing t1, and starts operation according to the second condition. Note that when the control unit 51 selects the second condition from among a plurality of temperature-lowering conditions, it outputs a signal indicating the second condition to the reflow furnace 100. As a result, the reflow furnace 100 can start operation according to the second condition.

[0096] The reflow furnace 100 outputs a status signal according to the operation mode. In the example shown in Fig. 8, a high-level status signal indicates that the operation mode of the reflow furnace 100 is the energy saving mode. A low-level status signal indicates that the operation mode of the reflow furnace 100 is the normal mode.

[0097] The estimation unit 52 outputs a first estimate of the temperature inside the furnace at the timing t1 when the operation mode of the reflow furnace 100 is switched from the normal mode to the energy saving mode. In the example shown in Fig. 8, the estimation unit 52 outputs the target temperature TT as the first estimate.

[0098] In one aspect, the determination unit 53 may determine a first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode based on the first estimated value, the timing t3, the target temperature decreasing model, and the target temperature increasing model.

[0099] Specifically, as shown in FIG. 8, the determination unit 53 identifies a point Pc corresponding to the timing t1 and the first estimated value in a graph having a time axis and a temperature axis. The determination unit 53 translates a curve 71 represented by the target temperature drop model along the time axis so as to pass through the point Pc. Furthermore, the determination unit 53 identifies a point Pd corresponding to the timing t3 and the target temperature TT in the graph. The determination unit 53 translates a curve 72 represented by the target temperature rise model along the time axis so as to pass through the point Pd. The determination unit 53 identifies an intersection Pe of the curves 71 and 72 in the graph. The determination unit 53 determines the timing t2 corresponding to the intersection Pe as the first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode.

[0100] In another aspect, the determination unit 53 may calculate, for each unit time, a fourth timing at which the reflow furnace 100 returns to the target state, assuming that the operating mode is currently switched from the energy saving mode to the normal mode, based on the estimated value and the target temperature rise model.

[0101] For example, when the current time is timing t4, the determination unit 53 calculates the fourth timing as follows. That is, as shown in Fig. 8, in a graph having a time axis and a temperature axis, the determination unit 53 translates a curve 73 represented by the target heating model along the time axis so as to pass through timing t4 and a point Pf corresponding to the estimated value at timing t4. The determination unit 53 identifies an intersection Pg between the curve 73 and a straight line 74 that is perpendicular to the temperature axis and indicates the target temperature TT. The determination unit 53 calculates timing t5 corresponding to the intersection Pg as the fourth timing.

[0102] The determination unit 53 may determine the present time as the first time when the condition that the time difference between the fourth timing and timing t3 is equal to or less than the threshold is satisfied. In this way, when timing t2 is the present time, the determination unit 53 can determine that the condition that the time difference between the fourth timing and timing t3 is equal to or less than the threshold is satisfied. As a result, the determination unit 53 can determine that timing t2 is the first time for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode.

[0103] The control unit 51 generates a control signal so that the operation mode is switched from the normal mode to the energy saving mode at the first timing determined by the determination unit 53.

[0104] (Processing example 2) Processing example 2 is based on the first case including the following events (a) and (b). (a) Based on a production plan, a user sets the time period from timing t11 to timing t14 as an idling time period, whereby the heating furnace is controlled in the energy saving mode from timing t11 to timing t12, and in the normal mode from timing t12 to timing t14. (b) At timing t13 between timing t12 and timing t14, a problem occurs in the device upstream of the heating furnace. Therefore, at timing t13, the user forcibly switches the operation mode of the heating furnace back to the energy saving mode. Furthermore, the user extends the production start time of the heating furnace from timing t14 to timing t16.

[0105] FIG. 9 is a diagram for explaining a processing example of the conventional technology assuming the first case. FIG. 9 shows a control signal and a graph showing the change over time in the temperature inside the furnace. In the conventional technology disclosed in Patent Document 1, the operation mode of the furnace is switched to the energy-saving mode at timing t11 in accordance with the above event (a). Furthermore, in the conventional technology, the operation mode of the furnace is switched to the normal mode at timing t12 when the remaining time until timing t14 becomes equal to or less than the reference return time T2. The reference return time T2 is determined in advance according to the time T1 from timing t11 when the energy-saving mode is started to timing t14 when the furnace is returned to the target state.

[0106] When event (b) occurs, the time period from timing t13 to timing t16 is set as a new idling time period. Therefore, a new reference return time T4 is set based on the time T3 from timing t13 to timing t16. As a result, in the conventional technology, the operation mode of the furnace is switched to the normal mode at timing t15 when the remaining time until timing t16 becomes equal to or shorter than the reference return time T4.

[0107] However, in the conventional technology, the reference return time T4 is determined on the premise that the heating furnace is in the target state at the start timing of the idling period (timing t13 in the example shown in FIG. 9). As shown in FIG. 9, timing t13 is a timing during which the heating furnace is returning to the target state. Therefore, at timing t13, the temperature inside the heating furnace is lower than the target temperature TT. As a result, when the heating furnace is switched to the normal mode at timing t15, timing t17 at which the temperature inside the furnace reaches the target temperature TT is delayed by time T5 from timing t16. This causes products to stagnate in the front stage of the heating furnace. In other words, the production efficiency of the products decreases.

[0108] 10 is a diagram for explaining a processing example 2 of the control device according to the present embodiment when the first case is assumed. According to the control device 500 according to the present embodiment, the estimation unit 52 outputs an estimated value of the temperature inside the reflow furnace 100. Therefore, the determination unit 53 can use the estimated value to determine a first timing for switching the operation mode from the energy saving mode to the normal mode so that the reflow furnace 100 returns to the target state at timing t16 corresponding to the production start time after the extension. In the example shown in FIG. 10, the determination unit 53 determines timing t15a as the first timing.

[0109] Specifically, as described in the processing example 1, in one aspect, the determination unit 53 uses a first estimate of the temperature inside the furnace at the timing t13 when the operation mode of the reflow furnace 100 is switched from the normal mode to the energy saving mode. The determination unit 53 determines the first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode based on the first estimate, the timing t16, the target temperature drop model, and the target temperature rise model.

[0110] Alternatively, in another aspect, the determination unit 53 calculates, for each unit time, a fourth timing at which the reflow furnace 100 will return to the target state when it is assumed that the operation mode is switched from the energy saving mode to the normal mode at the present time, based on the estimated value and the target temperature rise model. Then, the determination unit 53 determines the present time as the first timing in response to the condition being satisfied that the time difference between the fourth timing and timing t16 is equal to or smaller than a threshold value.

[0111] By switching the operation mode of the reflow furnace 100 to the normal mode at the first timing, the reflow furnace 100 can return to the target state at timing t16.

[0112] (Processing example 3) Processing example 3 is based on the second case including the following events (c) and (d). (c) Based on the production plan, the user sets the time period from timing t21 to timing t23 as an idling time period. (d) At timing t20, which is prior to timing t21, a problem occurs in a device upstream of the heating furnace. Therefore, at timing t20, the user directly operates the heating furnace to forcibly switch the operation mode to the energy saving mode.

[0113] Fig. 11 is a diagram for explaining an example of control of the prior art assuming the second case. Fig. 11 shows a graph showing the change over time in the control signal and the temperature inside the heating furnace. In Fig. 11, a solid line 75 shows the change over time in the temperature inside the heating furnace. A dashed line 76 shows the change over time in the temperature inside the heating furnace when it is assumed that the event (d) does not exist.

[0114] As shown by the solid line 75, at time t20, the operation mode of the furnace is switched to the energy saving mode, and the temperature inside the furnace starts to drop from the target temperature TT. In the prior art disclosed in Patent Document 1, in accordance with the above event (c), the operation mode of the furnace is switched to the normal mode at time t22 when the remaining time until time t23 is equal to or less than the reference return time T7. The reference return time T7 is determined in advance according to the time T6 from time t21 to time t23.

[0115] In the prior art, the reference return time T7 is set on the premise that the furnace is in the target state at the start timing of the idling period (timing t21 in the example shown in FIG. 11). That is, as shown by the dashed line 76, the operation mode of the furnace is switched to the energy saving mode at timing t21, and the operation mode of the furnace is switched to the normal mode at timing t22, so that the furnace returns to the target state at timing t23.

[0116] However, as shown in FIG. 11, the temperature inside the furnace starts to decrease at timing t20, which is before timing t21. Therefore, at timing t21, the temperature inside the furnace is lower than the target temperature TT. As a result, when the heating furnace is switched to the normal mode at timing t22, timing t24, at which the temperature inside the furnace reaches the target temperature TT, is delayed by time T8 from timing t23. This causes products to stagnate in the front stage of the heating furnace. In other words, the production efficiency of the products decreases.

[0117] Fig. 12 is a diagram for explaining a processing example 3 of the control device according to the present embodiment when the second case is assumed. In Fig. 12, a solid line 75a indicates a change in temperature inside the reflow furnace 100. A dashed line 76 indicates a change in temperature inside the reflow furnace 100 when it is assumed that the event (d) does not exist.

[0118] The control device 500 according to this embodiment receives a status signal from the reflow furnace 100 and determines the operation mode of the reflow furnace 100 based on the status signal. Then, the estimation unit 52 selects a model (target temperature drop model or target temperature rise model) according to the operation mode of the reflow furnace 100, and outputs an estimate of the temperature inside the reflow furnace 100 based on the selected model. Therefore, the estimation unit 52 can output an estimate along the solid line 75a after timing t20.

[0119] The determination unit 53 can use the estimated value to determine the first timing for switching the operation mode from the energy saving mode to the normal mode so that the reflow furnace 100 returns to the target state at timing t23 corresponding to the production start time. In the example shown in Fig. 12, the determination unit 53 determines timing t22a as the first timing.

[0120] Specifically, as described in the processing example 1, in one aspect, the determination unit 53 uses a first estimate of the temperature inside the furnace at the timing t20 when the operation mode of the reflow furnace 100 is switched from the normal mode to the energy saving mode. The determination unit 53 determines the first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode based on the first estimate, the timing t23, the target temperature drop model, and the target temperature rise model.

[0121] Alternatively, in another aspect, the determination unit 53 calculates, for each unit time, a fourth timing at which the reflow furnace 100 will return to the target state when it is assumed that the operation mode is switched from the energy saving mode to the normal mode at the present time, based on the estimated value and the target temperature rise model. Then, the determination unit 53 determines the present time as the first timing in response to the condition being satisfied that the time difference between the fourth timing and timing t23 is equal to or smaller than a threshold value.

[0122] By switching the operation mode of the reflow furnace 100 to the normal mode at the first timing, the reflow furnace 100 can return to the target state at timing t23.

[0123] (Processing example 4) Processing example 4 is based on the third case including the following event (e). (e) At timing t31, a problem occurs in the upstream device of the reflow furnace 100. Therefore, at timing t31, the user forcibly switches the operation mode to the energy saving mode. Since the time required for maintenance of the upstream device is unknown, the user does not set a production start time.

[0124] Fig. 13 is a diagram for explaining an example of processing of the control device according to the present embodiment when the third example is assumed. Fig. 13 shows the transition of the state signal and the estimated value output from the estimation unit 52.

[0125] The control device 500 according to this embodiment receives a status signal from the reflow furnace 100 and determines the operation mode of the reflow furnace 100 based on the status signal. According to event (e), the control device 500 determines that the operation mode of the reflow furnace 100 is the energy saving mode from timing t31. Therefore, the estimation unit 52 outputs an estimated value of the temperature inside the reflow furnace 100 based on the target temperature drop model from timing t31.

[0126] The determination unit 53 determines, for each unit time, information indicating a fourth timing at which the reflow furnace 100 returns to the target state, assuming that the operating mode is currently switched from the energy saving mode to the normal mode, based on the estimated value and the target temperature rise model.

[0127] For example, at timing t32, the determination unit 53 determines timing t33 ​​as the fourth timing. That is, as shown in Fig. 13, the determination unit 53 translates a curve 77 represented by the target heating model along the time axis so as to pass through timing t32 and a point Ph corresponding to the estimated value of the furnace temperature at timing t32. The determination unit 53 identifies an intersection Pi between the curve 77 and a straight line 78 that is perpendicular to the temperature axis and indicates the target temperature TT. The determination unit 53 calculates timing t33 ​​corresponding to the intersection Pi as the fourth timing.

[0128] In a similar manner, at timing t34, the determination unit 53 determines timing t35 as the fourth timing.

[0129] The forced switching of the operation mode of the reflow furnace 100 to the energy saving mode at timing t31 may be executed using the HMI 600 or may be executed using the PC 300 connected to the reflow furnace 100.

[0130] Fig. 14 is a diagram showing an example of a screen displayed on the HMI. Data for a screen 90 shown in Fig. 14 is generated by the control device 500. The screen 90 includes an indicator 91 and a button 92.

[0131] The indicator 91 indicates whether or not the operation mode of the reflow furnace 100 is the energy saving mode. For example, the indicator 91 is lit when the operation mode of the reflow furnace 100 is the energy saving mode. In the screen 90 shown in Fig. 14, the indicator 91 is turned off.

[0132] The button 92 is used to forcibly switch the operation mode of the reflow furnace 100 to the energy saving mode. In response to the button 92 being clicked, the control unit 51 generates a control signal to switch the operation mode to the energy saving mode.

[0133] Fig. 15 is a diagram showing another example of a screen displayed on the HMI. Data for a screen 90 shown in Fig. 15 is generated by the control device 500. The screen 90 includes, in addition to an indicator 91, a button 93 and a display field 94.

[0134] 15, the indicator 91 is turned on. That is, the indicator 91 indicates that the operation mode of the reflow furnace 100 is the energy saving mode.

[0135] The display field 94 indicates the fourth timing. That is, the determination unit 53 writes in the display field 94 text indicating the fourth timing.

[0136] The button 93 is used to forcibly switch the operation mode of the reflow furnace 100 to the normal mode. In response to the button 93 being clicked, the control unit 51 generates a control signal to switch the operation mode to the energy saving mode.

[0137] This allows the user to know the timing at which the reflow furnace 100 will return to the target state when the operation mode is currently switched from the energy saving mode to the normal mode by checking the display field 94. The user can then click the button 93 at an appropriate timing, taking into consideration the timing displayed in the display field 94 and the maintenance status of the preceding device. For example, the user can switch the operation mode of the reflow furnace 100 to the normal mode so that the reflow furnace 100 will return to the target state at the timing when maintenance of the preceding device is expected to be completed.

[0138] (Processing example 5) The processing example 5 is based on the premise that the storage unit 50 stores a plurality of temperature drop models 55 and a plurality of temperature rise models 56.

[0139] Fig. 16 is a diagram for explaining a processing example 5 of the control device according to the present embodiment. As shown in Fig. 16, the plurality of temperature drop models 55 includes three temperature drop models 55_1, 55_2, and 55_3. The temperature drop models 55_1, 55_2, and 55_3 correspond to different temperature drop conditions. The plurality of temperature rise models 56 includes three temperature rise models 56_1, 56_2, and 56_3. The temperature rise models 56_1, 56_2, and 56_3 correspond to different temperature rise conditions.

[0140] The control unit 51 selects a first condition from among a plurality of temperature increase conditions and selects a second condition from among a plurality of temperature decrease conditions according to the type of the printed circuit board 2 put into the reflow furnace 100.

[0141] The estimation unit 52 selects a temperature drop model corresponding to the second condition from among the temperature drop models 55_1, 55_2, and 55_3 as a target temperature drop model. The estimation unit 52 selects a temperature rise model corresponding to the first condition from among the temperature rise models 56_1, 56_2, and 56_3 as a target temperature rise model. The estimation unit 52 outputs an estimate of the temperature inside the reflow furnace 100 based on the target temperature drop model or the target temperature rise model.

[0142] Furthermore, the determining unit 53 determines the timing t42 at which the operation mode of the reflow furnace 100 is switched from the energy saving mode to the normal mode during the idling period from the timing t41 to the timing t43.

[0143] For example, the determination unit 53 determines the timing t42 based on the first estimated value of the furnace temperature at the timing t41, the timing t43, the target temperature drop model, and the target temperature rise model. Details of this determination method are as described with reference to FIG. 8.

[0144] In the processing example 5, as described above, the target temperature drop model is selected from among the temperature drop models 55_1, 55_2, and 55_3. Similarly, the target temperature rise model is selected from among the temperature rise models 56_1, 56_2, and 56_3. Therefore, there are 3×3=9 combinations of the target temperature drop model and the target temperature rise model. Regardless of which of the nine combinations is selected, the determination unit 53 can determine the timing t42 using the temperature drop models 55_1, 55_2, and 55_3 and the temperature rise models 56_1, 56_2, and 56_3 stored in the storage unit 50. Each of the temperature drop models 55_1, 55_2, and 55_3 and the temperature rise models 56_1, 56_2, and 56_3 is represented by, for example, a table indicating the correspondence between temperature and time. In this case, the storage unit 50 may store six tables in advance.

[0145] In contrast, the conventional technology described in Patent Document 1 requires a table that associates the length of the idling period with the reference recovery time for each combination when dealing with nine combinations. In other words, the conventional technology described in Patent Document 1 requires nine tables to be stored in advance.

[0146] Thus, according to the control device 500 of this embodiment, the amount of data required to determine the timing to switch the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode is smaller than that of the conventional technology described in Patent Document 1.

[0147] In other words, another object of the present disclosure is to reduce the amount of data required to determine when to switch the operating mode of the reflow furnace 100 from the energy saving mode to the normal mode, given that there are multiple operating conditions for each of the energy saving mode and the normal mode.

[0148] Furthermore, except for the case where the operation mode of the reflow furnace 100 is switched to the energy-saving mode at an unintended timing as in the above-mentioned first or second example, the furnace temperature at the timing when the operation mode is switched to the energy-saving mode is usually the target temperature TT. In this case, the determination unit 53 may use the target temperature TT as a first estimated value of the furnace temperature at the timing when the operation mode is switched to the energy-saving mode. That is, the determination unit 53 does not need to use the estimated value output from the estimation unit 52. Therefore, the above-mentioned other object can be achieved by the following configuration.

[0149] That is, the control device 500 for controlling the reflow furnace 100 includes a control unit 51 for controlling the operation mode of the reflow furnace 100 to either a normal mode or an energy-saving mode, and a determination unit 53 for determining information regarding switching of the operation mode. The normal mode is a mode in which the reflow furnace 100 operates according to a first condition for maintaining the reflow furnace 100 in a target state for heat-treating an object to be heated. The energy-saving mode is a mode in which the reflow furnace 100 operates according to a second condition that consumes less energy than the first condition. The control unit 51 selects a second condition from among a plurality of temperature-dropping conditions. The control unit 51 selects a first condition from among a plurality of temperature-raising conditions. The determination unit 53 selects a temperature-dropping model corresponding to the second condition as a target temperature-dropping model from among a plurality of temperature-dropping models corresponding to the plurality of temperature-dropping conditions. Each of the plurality of temperature-dropping models represents a change over time in the temperature inside the reflow furnace 100 when the reflow furnace 100 is operated according to the corresponding temperature-dropping condition from among the plurality of temperature-dropping conditions. The determination unit 53 selects a temperature rise model corresponding to a first condition from among a plurality of temperature rise models corresponding to a plurality of temperature rise conditions as a target temperature rise model. Each of the plurality of temperature rise models represents a change over time in the temperature inside the furnace when the reflow furnace 100 is operated according to a corresponding temperature rise condition from among the plurality of temperature rise conditions. The determination unit 53 determines a first timing for switching the operation mode of the reflow furnace 100 from the energy saving mode to the normal mode so that the reflow furnace 100 returns to the target state at the second timing based on a third timing at which the operation mode of the reflow furnace 100 is switched from the normal mode to the energy saving mode, a second timing at which the reflow furnace 100 should be returned to the target state, the target temperature drop model, and the target temperature rise model.

[0150] <Modification> (Variation 1) The temperature inside the reflow furnace 100 may vary depending on disturbance factors. The disturbance factors include the outside air temperature, the exhaust flow rate from the inert atmosphere chamber 13, the amount of air flowing into the inert atmosphere chamber 13, or the temperature of the air flowing into the inert atmosphere chamber 13.

[0151] Therefore, the estimation unit may adjust the estimated value estimated using the target temperature decreasing model or the target temperature increasing model by an adjustment amount output from the trained model by inputting the measured value of the disturbance factor to the trained model. The trained model is generated by machine learning using a training data set indicating the correspondence between the actual value of the disturbance factor and the amount of fluctuation in the furnace temperature due to the influence of the disturbance factor.

[0152] Fig. 17 is a diagram illustrating an example of the configuration of an estimation unit according to Modification 1. An estimation unit 52A illustrated in Fig. 17 differs from the estimation unit 52 illustrated in Fig. 5 in that it includes trained models 84 to 86 and adders 87 to 89.

[0153] The learned model 84 is generated by machine learning using a training data set that shows the correspondence between the actual values ​​of the disturbance factors when the operating mode of the reflow furnace 100 is in the energy saving mode and the amount of fluctuation in the internal temperature of the reflow furnace 100 during the cooling process due to the influence of the disturbance factors.

[0154] The learned model 85 is generated by machine learning using a training data set that shows the correspondence between the actual values ​​of the disturbance factors when the operating mode of the reflow furnace 100 is in normal mode and the amount of fluctuation in the internal temperature of the reflow furnace 100 during the heating process due to the influence of the disturbance factors.

[0155] The trained model 86 is generated by machine learning using a training data set that shows the correspondence between the actual values ​​of the disturbance factors and the amount of fluctuation in the temperature inside the reflow furnace 100 due to the influence of the disturbance factors, which is common to both the heating and cooling processes.

[0156] The types of disturbance factors input to the trained models 84 to 86 may be the same or different from each other. The trained models 84 to 86 receive the measured values ​​of the disturbance factors as inputs and output the amounts of fluctuation.

[0157] The adder 87 adds the amount of fluctuation output from the trained model 84 to the estimated value output from the calculator 80 .

[0158] The adder 88 adds the amount of fluctuation output from the trained model 85 to the estimated value output from the calculator 81 .

[0159] The adder 89 adds the amount of fluctuation output from the trained model 86 to the estimated value output from the adder 82 .

[0160] The estimation unit 52A outputs the output of the adder 89 as an adjusted estimated value, thereby enabling the estimation unit 52A to estimate the temperature inside the reflow furnace 100 with high accuracy.

[0161] In the control device according to the first modification, the determination unit 53 determines information regarding switching of the operation mode by using the adjusted estimated value of the furnace temperature.

[0162] (Variation 2) Fig. 18 is a diagram showing a functional configuration of a control device according to Modification 2. As shown in Fig. 18, a control device 500A according to Modification 2 differs from the control device 500 shown in Fig. 4 in that a generation unit 58 is provided.

[0163] The generating unit 58 generates a temperature drop model or a temperature rise model. The generating unit 58 acquires data indicating a change over time of a measured temperature inside the reflow furnace 100 when the reflow furnace 100 is operated according to a new temperature drop condition different from any of the temperature drop conditions corresponding to each of the one or more temperature drop models stored in the storage unit 50. The generating unit 58 generates a new temperature drop model based on the acquired data and stores it in the storage unit 50. Similarly, the generating unit 58 acquires data indicating a change over time of a measured temperature inside the reflow furnace 100 when the reflow furnace 100 is operated according to a new temperature rise condition different from any of the temperature rise conditions corresponding to each of the one or more temperature rise models stored in the storage unit 50. The generating unit 58 generates a new temperature rise model based on the acquired data and stores it in the storage unit 50.

[0164] The generating unit 58 generates the temperature decreasing model or the temperature increasing model during a learning period. The learning period is determined in advance. Alternatively, a certain idling time period may be set as the learning period.

[0165] (Variation 3) Fig. 19 is a diagram showing a functional configuration of a control device according to Modification 3. As shown in Fig. 19, a control device 500B according to Modification 3 is different from the control device 500 shown in Fig. 4 in that an optimization unit 59 is provided.

[0166] The optimization unit 59 optimizes the temperature drop model 55 stored in the storage unit 50. Specifically, the optimization unit 59 sets new temperature drop conditions by changing at least a part of the temperature drop conditions corresponding to the temperature drop model. The optimization unit 59 acquires data indicating the power consumption during an idling time period when the reflow furnace 100 is operated according to the new temperature drop conditions. When the power consumption after the temperature drop conditions are changed is smaller than the power consumption before the temperature drop conditions are changed, the optimization unit 59 updates the temperature drop conditions corresponding to the temperature drop model to the new temperature drop conditions. Then, the optimization unit 59 updates the temperature drop model 55 stored in the storage unit 50 to a temperature drop model indicating the change over time of the temperature inside the furnace when the reflow furnace 100 is operated according to the new temperature drop conditions. As a result, the temperature drop model 55 is updated to a temperature drop model corresponding to the temperature drop conditions optimal for reducing power consumption.

[0167] The optimization unit 59 may optimize the temperature rise model 56 stored in the storage unit 50 in a similar manner.

[0168] The optimization unit 59 optimizes the temperature drop model 55 or the temperature rise model 56 during the learning period. The learning period is determined in advance. Alternatively, a certain idling time period may be set as the learning period.

[0169] (Variation 4) Steps S1 to S5 shown in FIG. 6 are performed after the start-up operation of the reflow furnace 100. However, the processor 501 may output an estimated value of the furnace temperature from the start-up of the reflow furnace 100. In this case, when outputting the first estimated value, the processor 501 may output the previous estimated value T k-1 The outside air temperature or a predetermined temperature (for example, 20° C.) may be set as the temperature.

[0170] (Variation 5) The reflow furnace 100 may include a control device 500 .

[0171] (Variation 6) The invention according to this embodiment can also be realized as a non-transitory computer-readable medium that stores a program describing the processing contents for realizing each function of the control device 500.

[0172] §3 Supplementary Note As described above, the present embodiment includes the following disclosure. (Configuration 1) A control device (500) for controlling a heating furnace (100), a control unit (51, 501) for controlling an operation mode of the heating furnace (100) to either a first mode or a second mode; an estimation unit (52, 501) that outputs an estimated value of an inside temperature of the heating furnace (100); a determination unit (53, 501) that determines information regarding switching of the operation mode using the estimated value; the first mode is a mode in which the heating furnace (100) operates according to a first condition for maintaining the heating furnace (100) in a target state for heat-treating an object to be heated (2); the second mode is a mode in which the furnace (100) operates according to second conditions that consume less energy than the first conditions; the estimation unit (52, 501) outputs the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace (100) operates in accordance with the second condition, and the target temperature drop model represents a change over time in the temperature inside the furnace when the heating furnace (100) in the target state is operated in accordance with the second condition; The control device (500) wherein, when the operating mode is controlled so that the heating furnace (100) operates in accordance with the first condition, the estimation unit (52, 501) outputs the estimated value based on a target heating model, and the target heating model represents the change in temperature inside the furnace over time when the heating furnace (100), which is in a temperature state lower than the target state, is operated in accordance with the first condition. (Configuration 2) the information indicates a first timing for switching the operation mode from the second mode to the first mode, The control device (500) according to configuration 1, wherein the determination unit (53, 501) determines the information so that the heating furnace (100) is returned to the target state at a second timing when the heating furnace (100) should be returned to the target state. (Configuration 3) the estimation unit (52, 501) outputs a first estimated value of the furnace temperature at a third timing when the operation mode is switched from the first mode to the second mode, the third timing being before the first timing; The control device (500) according to configuration 2, wherein the determination unit (53, 501) determines the information based on the first estimated value, the second timing, the target temperature decreasing model, and the target temperature increasing model. (Configuration 4) When the operation mode is controlled so that the heating furnace (100) operates in accordance with the second condition, the determination unit: calculating a fourth timing at which the heating furnace (100) returns to the target state, assuming that the operation mode is currently switched from the second mode to the first mode, based on the estimated value and the target temperature rise model; The control device (500) according to configuration 2, wherein the control device (500) determines the current time as the first timing in response to a condition that a time difference between the fourth timing and the second timing is equal to or less than a threshold value being satisfied. (Configuration 5) the information indicates a fourth timing at which the furnace (100) will return to the target state, assuming that the furnace (100) is currently switched from the second mode to the first mode; The control device (500) according to configuration 1, wherein the determination unit (53, 501) determines the information based on the estimated value and the target temperature increase model. (Configuration 6) The control unit (51, 501) Selecting the second condition from a plurality of temperature decreasing conditions; Selecting the first condition from a plurality of temperature rise conditions; the estimation unit (52, 501) selects a temperature reduction model corresponding to the second condition from among a plurality of temperature reduction models (55) corresponding to the plurality of temperature reduction conditions as the target temperature reduction model, and each of the plurality of temperature reduction models (55) represents a change over time in the temperature inside the furnace when the heating furnace (100) is operated according to a corresponding temperature reduction condition from among the plurality of temperature reduction conditions; The control device (500) according to any one of configurations 1 to 5, wherein the estimation unit (52, 501) selects a heating model corresponding to the first condition from among a plurality of heating models (56) corresponding to the plurality of heating conditions as the target heating model, and each of the plurality of heating models (56) represents a change in temperature over time in the furnace when the heating furnace (100) is operated according to a corresponding heating condition from among the plurality of heating conditions. (Configuration 7) The estimation unit (52, 501) adjusts the estimated value by an adjustment amount output from the trained model by inputting a measured value of a disturbance factor to the trained model; A control device (500) according to any one of configurations 1 to 6, wherein the learned model is generated by machine learning using a training data set showing a correspondence between an actual value of the disturbance factor and an amount of fluctuation in the furnace temperature due to the influence of the disturbance factor. (Configuration 8) A control program for controlling a heating furnace (100), comprising: On the computer, Controlling the operation mode of the heating furnace (100) to either a first mode or a second mode; outputting an estimate of the temperature inside the heating furnace (100); and and determining information for switching the operation mode using the estimated value. the first mode is a mode in which the furnace (100) operates according to a first condition for maintaining the furnace (100) in a target state for heat-treating an object (2); the second mode is a mode in which the heating furnace operates according to second conditions that consume less energy than the first conditions; the outputting includes outputting the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace (100) operates in accordance with the second condition, the target temperature drop model representing a change over time in the temperature inside the furnace when the heating furnace (100) in the target state is operated in accordance with the second condition; A control program, wherein the outputting includes outputting the estimated value based on a target heating model when the operating mode is controlled so that the heating furnace (100) operates in accordance with the first condition, and the target heating model represents the change in temperature inside the furnace over time when the heating furnace (100), which is in a temperature state lower than the target state, is operated in accordance with the first condition. (Configuration 9) A method for controlling a heating furnace (100), comprising the steps of: Controlling the operation mode of the heating furnace (100) to either a first mode or a second mode; outputting an estimate of the temperature inside the heating furnace (100); and and determining information for switching the operation mode using the estimated value; the first mode is a mode in which the furnace (100) operates according to a first condition for maintaining the furnace (100) in a target state for heat-treating an object (2); the second mode is a mode in which the furnace operates according to second conditions that consume less energy than the first conditions; the outputting includes outputting the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace (100) operates in accordance with the second condition, the target temperature drop model representing a change over time in the temperature inside the furnace when the heating furnace (100) in the target state is operated in accordance with the second condition; The outputting includes outputting the estimated value based on a target heating model when the operating mode is controlled so that the heating furnace (100) operates in accordance with the first condition, and the target heating model represents the change in temperature inside the furnace over time when the heating furnace (100), which is in a temperature state lower than the target state, is operated in accordance with the first condition. (Configuration 10) A heating furnace (100) comprising the control device (500) according to any one of configurations 1 to 7. (Configuration 11) A control device (500) for controlling a heating furnace (100), a control unit (51, 501) for controlling an operation mode of the heating furnace (100) to either a first mode or a second mode; A determination unit (53, 501) for determining information regarding switching of the operation mode, the first mode is a mode in which the heating furnace (100) operates according to a first condition for maintaining the heating furnace (100) in a target state for heat-treating an object to be heated (2); the second mode is a mode in which the furnace (100) operates according to second conditions that consume less energy than the first conditions; The control unit (51, 501) Selecting the second condition from a plurality of temperature decreasing conditions; Selecting the first condition from a plurality of temperature rise conditions; the determination unit (53, 501) selects, as the target temperature reduction model, a temperature reduction model corresponding to the second condition from among a plurality of temperature reduction models (55) corresponding to the plurality of temperature reduction conditions, and each of the plurality of temperature reduction models (55) represents a change over time in an internal temperature of the heating furnace (100) when the heating furnace (100) is operated according to a corresponding temperature reduction condition from among the plurality of temperature reduction conditions; the determination unit (53, 501) selects, as the target heating model, a heating model corresponding to the first condition from among a plurality of heating models (56) corresponding to the plurality of heating conditions, and each of the plurality of heating models (56) represents a change over time in the temperature inside the furnace when the heating furnace (100) is operated according to a corresponding heating condition from among the plurality of heating conditions; The control device (100), wherein the determination unit (53, 501) determines a first timing for switching the operation mode from the second mode to the first mode based on a third timing at which the operation mode is switched from the first mode to the second mode, a second timing at which the heating furnace (100) should be returned to a target state, the target temperature drop model, and the target temperature increase model, so that the heating furnace (100) returns to the target state at the second timing.

[0173] Although the embodiment of the present invention has been described, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0174] 1 Production system, 2 Printed circuit board, 11A-11N Heater, 12A-12N, 30A, 30B Fan, 13 Inert atmosphere chamber, 14 Nitrogen line, 15 Flow meter, 20 Conveyor, 21 Oxygen concentration sensor, 22 Power meter, 23 Chiller, 24, 25 Cooling pipe, 31A, 31B Motor, 32A, 32B Opening plate, 33A, 33B Damper motor, 35A, 35B Inverter, 36A, 36B Duct, 50 Memory unit, 51 Control unit, 52, 52A Estimation unit, 53 Determination unit, 55 Temperature drop model, 56 Temperature rise model, 58 Generation unit, 59 Optimization unit, 60, 90 Screen, 61, 62 Input field, 80, 81 Calculator, 82, 87, 88, 89 Adder, 83 Delay element, 84, 85, 86 Trained model, 91 Indicator, 92, 93 Button, 94 Display, 100 Reflow oven, 101 Controller, 102 Temperature control unit, 109, 219, 229, 239, 249, 259, 269, 319 Emergency lamp, 110 System program, 111 User program, 210 Loader, 220 Solder printer, 230, 260 Inspection device, 240 High-speed mounter, 250 High-precision mounter, 300 PC, 310 Unloader, 500, 500A, 500B Control device, 501 Processor, 502 Chip set, 503 Main memory, 504 Storage, 505 Control system network controller, 506 Information system network controller, 507 USB controller, 508 Memory card interface, 512 Information group, 520 Memory card, 600 HMI.

Claims

1. A control device for controlling a heating furnace, a control unit that controls an operation mode of the heating furnace to either a first mode or a second mode; an estimation unit that outputs an estimated value of the inside temperature of the heating furnace; a determination unit that determines information regarding switching of the operation mode by using the estimated value; the first mode is a mode in which the furnace operates according to a first condition for maintaining the furnace in a target state for heat-treating an object to be heated; the second mode is a mode in which the heating furnace operates according to second conditions that consume less energy than the first conditions; the estimation unit outputs the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace operates in accordance with the second condition, and the target temperature drop model represents a change over time in the temperature inside the furnace when the heating furnace in the target state is operated in accordance with the second condition; A control device, wherein the estimation unit outputs the estimated value based on a target heating model when the operating mode is controlled so that the heating furnace operates in accordance with the first condition, and the target heating model represents the change in temperature inside the furnace over time when the heating furnace, which is in a temperature state lower than the target state, is operated in accordance with the first condition.

2. the information indicates a first timing for switching the operation mode from the second mode to the first mode, The control device according to claim 1 , wherein the determination unit determines the information such that the furnace is returned to the target state at a second timing when the furnace should be returned to the target state.

3. the estimation unit outputs a first estimated value of the furnace temperature at a third timing when the operation mode is switched from the first mode to the second mode, the third timing being before the first timing; The control device according to claim 2 , wherein the determination unit determines the information based on the first estimated value, the second timing, the target temperature decreasing model, and the target temperature increasing model.

4. When the operation mode is controlled so that the heating furnace operates in accordance with the second condition, the determination unit: calculating a fourth timing at which the heating furnace returns to the target state, assuming that the operation mode is currently switched from the second mode to the first mode, based on the estimated value and the target temperature rise model; The control device according to claim 2 , wherein the control device determines the current time to be the first time when a condition that a time difference between the fourth time point and the second time point is equal to or smaller than a threshold is satisfied.

5. the information indicates a fourth timing at which the furnace will return to the target state, assuming that the furnace is currently switched from the second mode to the first mode; The control device according to claim 1 , wherein the determination unit determines the information based on the estimated value and the target temperature rise model.

6. The control unit is Selecting the second condition from a plurality of temperature decreasing conditions; Selecting the first condition from a plurality of temperature rise conditions; the estimation unit selects, as the target temperature reduction model, a temperature reduction model corresponding to the second condition from among a plurality of temperature reduction models corresponding to the plurality of temperature reduction conditions, and each of the plurality of temperature reduction models represents a change over time in the temperature inside the furnace when the heating furnace is operated according to a corresponding temperature reduction condition from among the plurality of temperature reduction conditions; 2. The control device according to claim 1, wherein the estimation unit selects a heating model corresponding to the first condition from among a plurality of heating models corresponding to the plurality of heating conditions as the target heating model, and each of the plurality of heating models represents a change in temperature inside the furnace over time when the heating furnace is operated according to a corresponding heating condition from among the plurality of heating conditions.

7. the estimation unit adjusts the estimated value by an adjustment amount output from a trained model by inputting a measured value of a disturbance factor to the trained model; The control device according to claim 1 , wherein the trained model is generated by machine learning using a training data set indicating a correspondence between an actual value of the disturbance factor and an amount of fluctuation in the furnace temperature due to the influence of the disturbance factor.

8. A control program for controlling a heating furnace, comprising: On the computer, Controlling an operation mode of the heating furnace to either a first mode or a second mode; outputting an estimate of an internal temperature of the heating furnace; and determining information for switching the operation mode using the estimated value. the first mode is a mode in which the furnace operates according to a first condition for maintaining the furnace in a target state for heat-treating an object to be heated; the second mode is a mode in which the heating furnace operates according to second conditions that consume less energy than the first conditions; The outputting includes outputting the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace operates in accordance with the second condition, the target temperature drop model representing a change over time in the temperature inside the furnace when the heating furnace in the target state is operated in accordance with the second condition, A control program in which the outputting includes outputting the estimated value based on a target heating model when the operating mode is controlled so that the heating furnace operates in accordance with the first condition, the target heating model representing the change in temperature inside the furnace over time when the heating furnace, which is in a temperature state lower than the target state, is operated in accordance with the first condition.

9. A method for controlling a heating furnace, comprising the steps of: Controlling an operation mode of the heating furnace to either a first mode or a second mode; outputting an estimate of an internal temperature of the heating furnace; and determining information for switching the operation mode using the estimated value; the first mode is a mode in which the furnace operates according to a first condition for maintaining the furnace in a target state for heat-treating an object to be heated; the second mode is a mode in which the heating furnace operates according to second conditions that consume less energy than the first conditions; The outputting includes outputting the estimated value based on a target temperature drop model when the operation mode is controlled so that the heating furnace operates in accordance with the second condition, the target temperature drop model representing a change over time in the temperature inside the furnace when the heating furnace in the target state is operated in accordance with the second condition, The outputting includes outputting the estimated value based on a target heating model when the operating mode is controlled so that the heating furnace operates in accordance with the first condition, and the target heating model represents the change in temperature inside the furnace over time when the heating furnace, which is in a state of a temperature lower than the target state, is operated in accordance with the first condition.

10. A heating furnace comprising a control device according to any one of claims 1 to 7.

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