Conveyor heating device and detector

Abstract

To detect a possibility that the rotary shaft in the motor of a fan(s) fixes.SOLUTION: A conveyance heating device comprises: a heating apparatus equipped with one or more furnace bodies, in which each furnace body is provided with a fan and hot wind is blown to the object to be heated by the fan(s); and conveyance means for conveying a workpiece to the heating apparatus. The conveyance heating device further comprises: an inverter provided on the motor of each fan; and a controller to be fed with a monitor signal showing the size of the load of the motor from the inverter, in which the controller determines whether it lies in a measuring possible range or not, and threshold determination for the monitor signal directly after the rotation start of the motor(s) is performed in the measuring possible range to detect a possibility of the fixation of the motor(s).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a transport and heating device and a detection device that are applied to, for example, a reflow device. [Background technology]

[0002] When a reflow machine is operated, the flux of the solder paste supplied onto the board turns into fumes during the heating stage, which then liquefy and adhere to the inside of the furnace. The liquefied flux adheres to the board and causes board defects. To keep the inside of the furnace clean, for example, a cooling type flux recovery device is installed. However, even if a flux recovery device is used, flux contamination accumulates if the reflow machine is used for a long period of time.

[0003] Hot air reflow equipment is generally equipped with a blower to supply and circulate hot air to each zone. Flux gradually accumulates on the blower inside the casing and around it. If the attached flux cools and the rotating shaft of the blower becomes stuck, problems such as the equipment being unable to operate when it is started up (restarted) can occur.

[0004] For example, Patent Document 1 describes a flux recovery device that can efficiently and reliably recover vaporized flux in a liquefied state having fluidity before solidification in order to prevent vaporized flux from adhering to the rotating shaft of a motor that rotates a fan and solidifying. Specifically, a drain part is provided around the rotating shaft to allow the flux generated by the reflow process to flow in and to discharge it to the outside.

[0005] Moreover, in Patent Document 2, since the piping arranged between the drain part and the flux collection vessel extends obliquely, the flux flowing from the drain part stagnates in the piping, and the flux accumulates and solidifies in the piping. In order to solve this problem, a configuration is described in which the pressure inside the flux collection part is reduced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5540680 [Patent Document 2] Patent No. 5565071 Summary of the Invention [Problem to be solved by the invention]

[0007] The devices described in Patent Documents 1 and 2 collect flux in a liquefied state before it solidifies around the rotating shaft of the blower, but even if such a flux collection device is installed, the flux gradually accumulates and adheres to the rotating shaft, which can cause the rotating shaft to stick. When the flux sticks, the reflow device cannot be operated, and the motor must be replaced. In the past, it was not possible to detect the possibility of the flux sticking in advance, and the sticking was only discovered after the reflow device had started operating. This caused the problem of unexpected interruptions to the reflow device's operations, which resulted in significant changes to the production schedule.

[0008] SUMMARY OF THE PRESENT DISCLOSURE ... An object of the present invention is to provide a transporting and heating device and a detection device that are capable of detecting the possibility of a rotating shaft becoming stuck. [Means for solving the problem]

[0009] The present invention relates to a heating device having one or more furnace bodies, a blower provided in the furnace body, and configured to blow hot air onto an object to be heated by the blower, and a conveying means for conveying a workpiece to the heating device. an inverter provided for a motor of the blower; A control device is provided to which a monitor signal indicating the magnitude of the load on the motor is supplied from the inverter, This is a conveying and heating device in which the control device determines whether or not the measurement is within a measurable range, and in the measurable range, detects the possibility of the motor sticking by making a threshold judgment on the monitor signal immediately after the motor starts to rotate. Effect of the Invention

[0010] According to at least one embodiment, it is possible to detect the possibility that the rotating shaft of the motor of the blower is stuck. Note that the effects described here are not necessarily limited, and any of the effects described in the present invention may be used. In addition, the contents of the present invention should not be interpreted as being limited to the effects exemplified in the following description. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a reflow apparatus to which the present invention can be applied. [Diagram 2] FIG. 2 is a graph showing an example of a temperature profile during reflow. [Diagram 3] FIG. 3 is a cross-sectional view showing the configuration of the furnace body. [Figure 4] FIG. 4 is a block diagram showing a system configuration according to an embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart showing a process flow according to an embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing an example of the change over time in the ambient temperature and the temperature at the stuck portion detected by the temperature detector. [Figure 7] FIG. 7 is a graph showing an example of a change in torque current over time. BEST MODE FOR CARRYING OUT THEINVENTION

[0012] The present invention will be described below with reference to the embodiments in the following order. <1. An example of a reflow device> <2. Mechanism of contamination caused by flux> <3. Motor sticking detection> <4. Modifications> It should be noted that the embodiment described below is a preferred specific example of the present invention, and various technically preferable limitations are included; however, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited to these embodiments.

[0013] <1. An example of a reflow device> Fig. 1 shows a schematic configuration of a conventional reflow apparatus 101 to which the present invention can be applied. The reflow apparatus 101 includes a reflow furnace 102, a conveyor chain 103 as a conveying means for passing an object to be heated, for example a printed circuit board (hereinafter referred to as a workpiece) W having surface-mount electronic components mounted on both sides, through the reflow furnace 102, rotors (idlers, sprockets, etc.) 105a, 105b, 105c, 105d that define the movement path of the conveyor chain 103, and an outer plate 106. Note that Fig. 1 shows only one of two parallel conveyor chains, conveyor chain 103.

[0014] The reflow furnace 102 heats the workpiece W from above and below, and then cools it after heating. The conveyor chain 103 is one of two conveyor chains arranged parallel to the conveying direction. For example, a roller chain is used as the conveyor chain 103. The outer plate 106 is a case that covers the entire structure.

[0015] The workpiece W is carried into the reflow furnace 102 from the carry-in entrance 107, then transported by the transport chain 103 in the direction of the arrow (from left to right in FIG. 1) at a predetermined speed, and finally removed from the carry-out exit 108. Although not shown, a workpiece carry-in device for carrying in the workpiece W is provided in front of the carry-in entrance 107, and a workpiece unloading device for sending the workpiece W to the outside is disposed in the rear of the carry-out exit 108.

[0016] Along the transport path from the entrance 107 to the exit 108, the reflow furnace 102 is divided into, for example, nine zones Z1 to Z9, and these zones Z1 to Z9 are arranged in-line. The seven zones Z1 to Z7 from the entrance 107 side are heating zones, and the two zones Z8 and Z9 on the exit 108 side are cooling zones. Forced cooling units (not shown) are provided in relation to the cooling zones Z8 and Z9. Note that the number of zones is an example, and other numbers of zones may be provided. The multiple zones Z1 to Z9 control the temperature of the workpiece W according to a temperature profile during reflow.

[0017] Each of the zones Z1 to Z7 has an upper furnace body and a lower furnace body. The upper furnace body and the lower furnace body included in each of the zones Z1 to Z7 are provided with a blower (e.g., a turbo fan) and a temperature detector (e.g., a thermocouple). The cooling zones Z8 and Z9 are also provided with a blower and a temperature detector. M1 and M11 are the blower motors of the zone Z1. M2 to M9 and M12 to M19 also indicate the blower motors of each zone.

[0018] The above-mentioned multiple zones Z1 to Z9 control the temperature of the workpiece W in accordance with a temperature profile during reflow. An example of a temperature profile is outlined in Figure 2. The horizontal axis is time, and the vertical axis is the surface temperature of the workpiece W, for example a printed wiring board on which electronic components are mounted. The first section is a temperature rise section R1 where the temperature rises due to heating, the next section is a preheat section R2 where the temperature is almost constant, the next section is a reflow (main heating) section R3, and the final section is a cooling section R4.

[0019] The temperature rise section R1 is a period in which the board is heated from room temperature to the preheat section R2 (for example, 150°C to 170°C). The preheat section R2 is a period in which, for example, isothermal heating is performed to activate the flux, remove the oxide film on the surface of the electrodes and solder powder, and eliminate uneven heating of the printed wiring board. The reflow section R3 (for example, peak temperature of 220°C to 240°C) is a period in which the solder melts and the joint is completed. In the reflow section R3, it is necessary to raise the temperature to a temperature exceeding the melting temperature of the solder. Even if the preheat section R2 has been passed, there is unevenness in the temperature rise, so that the reflow section R3 requires heating to a temperature exceeding the melting temperature of the solder. The final cooling section R4 is a period in which the printed wiring board is rapidly cooled and the solder composition is formed. In the case of lead-free solder, the temperature in the reflow section is higher (for example, 240°C to 260°C).

[0020] 2, curve 1 shows an example of a temperature profile for lead-free solder. An example of a temperature profile for Sn-Pb eutectic solder is shown by curve 2. Since the melting point of lead-free solder is higher than that of eutectic solder, the set temperatures in preheat section R2 and reflow section R3 are higher than those for eutectic solder.

[0021] In the reflow soldering equipment shown in Fig. 1, the temperature control of the heating section R1 in Fig. 2 is mainly handled by zones Z1 and Z2. The temperature control of the preheating section R2 is mainly handled by zones Z3, Z4, and Z5. The temperature control of the reflow section R3 is handled by zones Z6 and Z7. The temperature control of the cooling section R4 is handled by zones Z8 and Z9.

[0022] The configuration of one zone, for example, zone Z5, will be described with reference to Fig. 3. In the gap between the upper furnace body 1 and the lower furnace body 11, a workpiece W having surface-mount electronic components mounted on both sides of a printed wiring board is placed on a transport conveyor 21 and transported. The upper furnace body 1 and the lower furnace body 11 are filled with atmospheric gas, for example, nitrogen (N2) gas. The upper furnace body 1 and the lower furnace body 11 blow hot air (heated atmospheric gas) onto the workpiece W to heat it. Infrared rays may be irradiated together with the hot air.

[0023] The upper furnace body 1 is composed of a main heating source 2, a sub-heating source 3, a blower 4, a heat storage member 5, a hot air circulation duct 6, an opening 7, etc. The lower furnace body 11 is, for example, almost similar to the lower furnace body 1 described above, and is equipped with a main heating source 12, a sub-heating source 13, a blower 14, a heat storage member 15, a hot air circulation duct 16, an opening 17, etc. The blower 4 has a motor M5, a motor mounting plate 8, and a rotating blade 9. A gap 10 exists between the motor mounting plate 8 and the rotating blade 9. Similarly, the blower 14 has a motor M15, a motor mounting plate 18, and a rotating blade 19. A gap 20 exists between the motor mounting plate 18 and the rotating blade 19. As the blower, a centrifugal fan such as a turbo fan or a sirocco fan, an axial blower, etc. may be used. The configuration of the furnace body shown in FIG. 3 is an example, and other configurations may be used.

[0024] Hot air is blown onto the workpiece W through the openings 7 and 17. The main heating source 2, the main heating source 12, the sub-heating source 3 and the sub-heating source 13 are composed of, for example, electric heaters. The heat storage members 5 and 15 are made of, for example, aluminum and have a large number of holes through which the hot air passes and is blown onto the workpiece W.

[0025] For example, in the upper furnace body 1, hot air is circulated by the blower 4. That is, the hot air circulates through the route (main heating source 2 → heat storage member 3 → opening 7 → workpiece W → hot air circulation duct 6 → auxiliary heating source 3 → hot air circulation duct 6 → blower 4 → main heating source 2). Hot air circulates in the lower furnace body 11 in the same manner.

[0026] The atmospheric gas in zone Z5 is sent to a flux collection device (not shown) through a pipe 22. In the flux collection device, the flux in the flux fumes is removed and collected, and purified gas with reduced or removed flux is generated. The gas purified by the flux collection device is introduced into the lower furnace body 11 through a pipe 23. In the upper furnace body 1, gas purified by the flux collection device is also introduced in the same manner.

[0027] <2. Mechanism of contamination caused by flux> The mechanism of contamination by flux in the above-mentioned reflow device will be described. Here, the contamination refers to the flux adhering to the periphery of the rotating shaft of the motor of the blower of each furnace body. For example, it means the flux adhering to the gap 10 between the motor mounting plate 8 and the rotating blade 9, and the gap 20 between the motor mounting plate 18 and the rotating blade 19 of the blower of each furnace body. The contamination is mainly composed of resin such as rosin contained in the flux, and has the property that the viscosity increases as the temperature decreases, and further, the viscosity increases as the temperature decreases. When there is a lot of flux and the flux solidifies, the rotating shaft of the blower motor is fixed. The gaps 10 and 20 are the fixing points. Note that the temperature values ​​and the elapsed time values ​​in the following explanation are only examples.

[0028] Stage 1. Reflow machine in operation Blower: rotating, Dirt: low viscosity, Load: low, Temperature of stuck area: 250℃ Stage 2. Immediately after the reflow machine stops Blower: stopped, Dirt: low viscosity, Load: low, Temperature of stuck area: 250℃ Stage 3. 30 minutes after the reflow machine is stopped Blower: Stopped, Dirt: Low viscosity, Load: Low, Temperature of stuck area: 200℃ Stage 4. 400 minutes after reflow machine stopped Blower: Stopped, Dirt: Medium to low viscosity, Load: Medium, Temperature of stuck area: 100℃ Stage 5. 800 minutes after reflow machine stopped Blower: Stopped, Dirt: Medium viscosity, Load: Medium, Temperature of stuck area: 50℃ Stage 6. One day after the reflow machine stopped Blower: stopped, Dirt: high viscosity, Load: high, Temperature of stuck area: 30℃

[0029] If there is a lot of dirt in stage 6 described above, a large amount of dirt will solidify, causing the rotating shaft to stick and the blower to become unable to rotate. At the stage where the shaft has stuck, it is impossible to measure the possibility of the shaft sticking based on the motor load. On the other hand, in stages 1, 2 and 3, the viscosity of the dirt is low and the load on the blower motor is small because the temperature of the stuck part is high, making it unsuitable for measuring the possibility of the shaft sticking based on the motor load. Therefore, the present invention detects the possibility of the motor shaft sticking in the range (stage 4 and / or stage 5) where the value of the monitor signal (torque current) changes depending on the amount of flux.

[0030] <3. Device for detecting sticking possibility> The system configuration of one embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 shows a control signal system, and the power system is not shown. M1 to M19 indicate motors of the blower of the reflow device shown in Fig. 1, and INV1 to INV19 are inverters that drive and control each motor. Furthermore, TH1 to TH19 are heat detectors (for example, thermocouples) for detecting the internal temperature of each furnace body. For example, the upper furnace body of zone Z5 is provided with a motor M5 for rotating the rotary blades of the blower and a heat detector TH5, and the lower furnace body is provided with a motor M15 for rotating the rotary blades of the blower and a heat detector TH15.

[0031] The inverters INV1 to INV19 are connected to a control device, for example, a programmable logic controller (referred to as PLC in FIG. 4 and the following description) 31 via a network 32. The PLC 31 supplies each of the inverters INV1 to INV19 with a control signal instructing the number of rotations, and the inverters INV1 to INV19 supply monitor signals, alarm signals, and the like to the PLC 31. The monitor signals indicate the magnitude of the loads on the motors M1 to M19, and are referred to as torque currents. The torque current is, for example, a signal with a value (level) corresponding to the load on the motor. In the above-mentioned stage 4 or stage 5, the value of the torque current indicates the amount of flux present around the rotating shaft.

[0032] The temperatures detected by the thermal detectors TH1 to TH19 are supplied to the PLC 31 via the network 33. A personal computer 34 is connected to the PLC 31. The personal computer 34 functions as a user interface. For example, the personal computer 34 issues rotation speed commands to the PLC 31 and displays an alarm screen. Note that a control device other than a PLC may be used to control the inverters INV1 to INV19.

[0033] A method of detecting the possibility of sticking performed by the PLC 31 will be described with reference to the flowchart of Fig. 5. This detection method is applied to each of the motors M1 to M19 of the blowers.

[0034] Step S1: The blower is stopped by stopping the operation of the reflow device. Step S2: It is determined whether the temperature detected by the detection temperature signal is equal to or lower than the first threshold temperature Tt1 (threshold determination). When the detection temperature is equal to or lower than the threshold temperature Tt1, it is determined that the temperature is within the measurable range (stages 4 and 5 described above). When the detection temperature is higher than the threshold temperature Tt1, it is not yet within the measurable range, and the temperature determination process of step S2 is performed. Step S3: If the determination result of step S2 is positive, it is determined whether the detected temperature is higher than a second threshold temperature Tt2 (threshold determination). If the detected temperature is higher than the threshold temperature Tt2, it is determined that the detected temperature is within the measurable range, and the next process is performed. If the detected temperature is equal to or lower than the threshold temperature Tt2, it is determined that the detected temperature is outside the measurable range, and an end process is performed.

[0035] Step S4: The rotation of the fan is started, and the torque current value from the inverters INV1 to INV19 is measured. The measured torque current value is the value immediately after the rotation is started. Step S5: It is determined whether the torque current value is greater than the upper threshold value It1. If the torque current value is equal to or less than the upper threshold value current, it is determined that the possibility of sticking has not been detected and the detection process ends. In this case, a message indicating that there is no possibility of sticking may be displayed on the screen of the microcomputer 34. Note that the detection process may not end in one run, but may be performed multiple times within the measurable range. In this case, the process is repeated again from the threshold value determination in step S2 after a predetermined time has elapsed (for example, when the next detection process becomes possible).

[0036] Step S6: If it is determined in step S5 that the torque current value is greater than the upper threshold value It1, a dirt detection abnormality alarm is generated, and the dirt detection abnormality alarm is displayed on the screen of the personal computer 34. An alarm sound may be generated by the personal computer 34. The process of step S6 ends the process of detecting the possibility of sticking. If a dirt detection abnormality alarm is generated, the user is prompted to stop operation of the reflow device and replace the blower (or motor) for which the alarm was generated with a clean blower (or motor).

[0037] As described above, the cause of the sticking of the rotating shafts of the motors M1 to M19 is that flux adheres to the sticking points (gaps 10 and 20) and the adhered flux solidifies. However, the spaces of the gaps 10 and 20 are small, and it is difficult to provide the heat detectors TH1 to TH19 in the gaps 10 and 20. In one embodiment of the present invention, the heat detectors TH1 to TH19 are provided inside the furnace body, and therefore the temperatures (atmospheric temperature) detected by the heat detectors TH1 to TH19 do not strictly match the temperature of the stuck points.

[0038] FIG. 6 shows an example of measuring the temperature at the stuck point (curve shown by a solid line) and the detected temperature (curve shown by a dashed line). The vertical axis is temperature (°C) and the horizontal axis is the time (min) elapsed since rotation was stopped. When time t1 has elapsed since rotation was stopped and the temperature at the stuck point falls below a first threshold temperature Tt1 (e.g., about 80°C), it enters the measurable range (Stage 4). In other words, this is the range in which no sticking has occurred and fluctuations in the load due to dirt affect the torque current. Furthermore, after time t2 when the detected temperature falls below a second threshold temperature Tt2 (e.g., about 50°C), if sticking has occurred, it becomes impossible to measure the load due to the torque current (Stage 6).

[0039] Therefore, the measurable range is the range from time t1 when the detected temperature is equal to or lower than the threshold temperature Tt1 to time t2 when the detected temperature is lower than the threshold temperature Tt2. In one embodiment, since the measurable range is determined by the detected temperature, the stuck point temperature is measured in advance, and the difference between the stuck point temperature and the detected temperature of the furnace body is measured in advance, and this difference is corrected. In the example shown in FIG. 6, since the detected temperature is slightly higher than the stuck point temperature, the detected temperature or the threshold temperatures Tt1 and Tt2 are corrected to make the determination. Note that the measurable range may be determined by the time elapsed since the rotation was stopped, without using the detected temperature.

[0040] The first threshold temperature Tt1 (threshold temperature at which the fan starts rotating) and the second threshold temperature Tt2 (threshold for determining the measurable range) are set by measuring the temperature inside the furnace and the state of the attached flux in advance. Table 1 shows an example of the results of measuring the relationship between them.

[0041] [Table 1]

[0042] In the example of Table 1, when the temperature inside the furnace is 40°C to 50°C, the attached flux is viscous and has a medium viscosity, and this temperature range is optimal as the timing to start measurement. When the temperature inside the furnace is 30°C to 40°C, the second most suitable timing to start measurement. Furthermore, when the temperature inside the furnace is 50°C to 60°C, the second most suitable timing to start measurement. When the temperature inside the furnace is less than 30°C, the flux solidifies, and when the temperature inside the furnace is 60°C or higher, the flux is in a liquid state, so this is not a suitable temperature to start measurement. Therefore, in the example of Table 1, the threshold temperature Tt1 is set within the range of 40°C to 50°C, and a temperature slightly higher than the furnace temperature of 30°C is set as the threshold temperature Tt2.

[0043] An example of the measurement result of the torque current is shown in FIG. 7. The vertical axis is the torque current value (A) and the horizontal axis is the elapsed time (about 10 ms) from the start of rotation of the motor. In FIG. 7, the upper threshold value It1, the lower threshold value It2, the normal value Ix, and the abnormal value Iy are shown. The torque current value is measured from the start of rotation until 1 to 2 seconds have elapsed. The abnormal value Iy is a torque current value that is greater than the upper threshold value It1 because a large amount of flux is attached to the stuck portion. The normal value Ix is a torque current value that falls within the range of the upper threshold value It1 and the lower threshold value It2. Note that, although FIG. 6 and FIG. 7 show the temperature change and the change in the torque current value as analog changes, the signals transmitted to the PLC 31 through the networks 32 and 33 are digital signals.

[0044] Table 2 shows an example of the relationship between the change in torque current and the attached flux. For example, the torque current value for a new product is 1.0 (A) (5 Hz, 200 W motor starting). In Table 2, this value is taken as the normal value Ix as an example. Table 2 shows the relationship between the change in torque current value and the state of the attached flux with respect to this torque current value. Note that the torque current value is the value immediately after rotation begins.

[0045] [Table 2]

[0046] When the torque current value is less than ±10% of the normal value, the attached flux is merely a thin coating, and there is no problem with starting the motor. When the torque current value is ±10% to ±20% of the normal value, the attached flux is in a state where the flux is attached, but the motor can be started. When the torque current value is 20% or more of the normal value, the flux solidifies, making it difficult to start the motor. In other words, the motor's rotating shaft may be stuck. In the example of Table 2, the threshold value of the torque current value is set to, for example, ±20% of the normal value.

[0047] The above-mentioned embodiment of the present invention can detect in advance the possibility that the rotating shaft of the blower of the reflow soldering device will stick as a result of a large amount of flux adhering to the stuck portion of the blower of the reflow soldering device. Therefore, unlike a situation in which the sticking is only discovered when the reflow soldering device is about to be restarted, it is possible to prevent the operation plan of the reflow soldering device from being significantly different from the plan.

[0048] <4. Modifications> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-mentioned embodiments, and various modifications based on the technical idea of ​​the present invention are possible. For example, the present invention is not limited to printed circuit boards, but can also be applied to reflow of flexible boards, boards in which rigid boards and flexible boards are bonded together, and rigid-flex boards that combine these. The present invention can also be applied to a reflow device with a single heating furnace (one zone). Furthermore, the present invention is not limited to reflow devices, but can also be applied to heating devices for curing resins, etc. The configurations, methods, steps, shapes, materials, and values ​​given in the above-mentioned embodiments are merely examples, and different configurations, methods, steps, shapes, materials, and values ​​may be used as necessary. The configurations, methods, steps, shapes, materials, and values ​​of the above-mentioned embodiments can be combined with each other as long as they do not deviate from the gist of the present invention. [Explanation of symbols]

[0049] 101: Reflow device, 103: Conveyor chain, W: Work, 1 ... upper furnace body, 4 ... blower, 8 ... motor mounting plate, 9 ... rotating blade, 10 gap, 11 lower furnace body, 18 motor mounting plate, 19...rotor blade, 20...gap, 31...PLC, M1~M19... Blower motor, INV1~INV19... Inverter, TH1~TH19 Temperature detector

Claims

1. A heating device having one or more furnace bodies, a blower provided in the furnace body, and configured to blow hot air onto an object to be heated by the blower, and a conveying means for conveying a workpiece to the heating device, an inverter provided for a motor of the blower; a control device to which a monitor signal indicating the magnitude of a load on the motor is supplied from the inverter; A conveying and heating device in which the control device determines whether or not the control device is within a measurable range, and within the measurable range, detects the possibility of the motor sticking by making a threshold judgment on the monitor signal immediately after the motor starts to rotate.

2. 2. The transporting and heating device according to claim 1, wherein the motor is stuck due to flux adhering to a periphery of a rotating shaft of the motor.

3. 3. The transporting and heating device according to claim 2, wherein the measurable range is a range in which the value of the monitor signal varies depending on the amount of the flux.

4. The furnace body is provided with a temperature detector, 4. The transporting and heating device according to claim 1, wherein the control device determines whether the temperature detected by the temperature detector is within the measurable range.

5. 5. The conveying and heating device according to claim 4, wherein the temperature detector is disposed in the furnace body at a location other than the periphery of the rotation shaft of the motor.

6. 6. The transporting and heating device according to claim 4, wherein the process of detecting the possibility of the motor sticking is performed a plurality of times within the measurable range.

7. a blower having a motor and a rotary blade rotated by the motor; an inverter provided for the motor; a control device to which a monitor signal indicating the magnitude of a load on the motor is supplied from the inverter; The detection device determines whether the control device is within a measurable range, and within the measurable range, detects the possibility of the motor sticking by making a threshold judgment on the monitor signal immediately after the motor starts to rotate.

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