Seal defect detection system and seal defect detection method

Abstract

To provide a seal defect detection system capable of accurately and efficiently detecting whether or not a seal defect has occurred. [Solution] The seal defect detection system comprises a temperature measurement unit, a temperature acquisition unit that acquires the temperatures of multiple measurement locations measured by the temperature measurement unit, a first judgment unit that determines whether any of the temperatures of the multiple measurement locations acquired by the temperature acquisition unit are within a predetermined temperature range in which upper and lower limit temperatures are set in advance, a second judgment unit that determines whether each of the temperatures of a predetermined number of consecutive measurement locations among the temperatures of the multiple measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference, and a seal defect detection unit that detects that a seal defect has occurred in the package if the first judgment unit determines that any of the temperatures of the multiple measurement locations is not within the predetermined temperature range or if the second judgment unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference.

Description

[Technical Field]

[0001] The present disclosure relates to a seal defect detection system and a seal defect detection method. [Background technology]

[0002] A technology relating to a heat-sealing line control device that heat-seals packaging materials has been disclosed (see, for example, Patent Document 1). The heat-sealing line control device disclosed in Patent Document 1 detects the temperature at each point along the width direction of the heat-sealed portion, and controls the heating conditions of the sealing machine so that the detected temperature falls within a predetermined appropriate temperature range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-144415 Summary of the Invention [Problem to be solved by the invention]

[0004] In a sealing device that seals a bag by thermal welding, sealing the bag while the contents, such as a powdery substance, are trapped can result in a defective seal. One method for detecting a defective seal is to visually inspect the sealed area. However, this method not only incurs labor costs, but also increases the likelihood of missing a defective seal. Visual inspection is particularly difficult when the package has a pattern, is colored, or if the powdery substance trapped in the sealed area is small, making visual inspection extremely difficult and increasing the likelihood of missing a defective seal. Furthermore, even when the temperature detected at the sealed area is controlled to fall within a predetermined optimum temperature range, as in the technology disclosed in Patent Document 1, defective seals may not be detected. A defective seal detection device that can accurately and efficiently detect whether a defective seal has occurred in a sealing device is needed.

[0005] Therefore, one of the objects is to provide a seal defect detection system and a seal defect detection method that can accurately and efficiently detect whether or not a seal defect has occurred. [Means for solving the problem]

[0006] A seal defect detection system according to the present disclosure is a system for detecting seal defects in a package sealed by heating. The seal defect detection system includes a temperature measurement unit that sequentially measures the temperature of a plurality of measurement locations in a seal area sealed along the width direction of the seal, a temperature acquisition unit that acquires the temperatures of the plurality of measurement locations measured by the temperature measurement unit, a first determination unit that determines whether any of the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is within a predetermined temperature range having preset upper and lower limit temperatures, a second determination unit that determines whether each of the temperatures of a predetermined number of consecutive measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference, and a seal defect detection unit that detects a seal defect in the package if the first determination unit determines that any of the temperatures of the plurality of measurement locations is not within the predetermined temperature range or if the second determination unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference. [Effects of the Invention]

[0007] According to the above-described sealing defect detection system and sealing defect detection method, it is possible to accurately and efficiently detect whether or not a sealing defect has occurred. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a seal defect detection system according to the first embodiment. [Figure 2] FIG. 2 is a schematic perspective view showing the appearance of a sealing device and a part of the seal defect detection system shown in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of a control panel included in the sealing device. [Figure 4] FIG. 4 is a schematic enlarged view showing the vicinity of the insertion opening, which is the sealed area of ​​the sealed package. [Figure 5] FIG. 5 is a diagram showing an example of measurement points in the seal area. [Figure 6] FIG. 6 is an enlarged view of the display shown in FIG. [Figure 7] FIG. 7 is a flow chart showing typical steps in detecting a seal defect using the seal defect detection system. [Figure 8] FIG. 8 is a diagram showing an example of what is displayed on the display when a relatively large amount of powdery foreign matter has become trapped, causing a sealing failure. [Figure 9] FIG. 9 is a schematic diagram of a sealing area in a state where a relatively large amount of powdery foreign matter is trapped. [Figure 10] FIG. 10 is a diagram showing an example of what is displayed on the display when a relatively small amount of powdery foreign matter is trapped, causing a sealing failure. [Figure 11] FIG. 11 is a schematic diagram of a sealing area in a state where a relatively small amount of powdery foreign matter is trapped. [Figure 12] FIG. 12 is a diagram showing an example of what is displayed on the display when a seal is tilted and a seal failure occurs. [Figure 13] FIG. 13 is a schematic diagram of the seal area with the seal tilted. [Figure 14] FIG. 14 is a diagram showing an example of what appears on the display when wrinkles occur in the sealing area, causing a sealing failure. [Figure 15] FIG. 15 is a schematic diagram of the seal area when wrinkles occur in the seal area. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Outline of the embodiment] The defective seal detection system disclosed herein is a system for detecting defective seals in a package sealed by heating. The defective seal detection system includes a temperature measurement unit that sequentially measures the temperature of a plurality of measurement locations in a sealed area sealed along the width direction of the seal, a temperature acquisition unit that acquires the temperatures of the plurality of measurement locations measured by the temperature measurement unit, a first determination unit that determines whether any of the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is within a predetermined temperature range in which upper and lower temperature limits are set in advance, a second determination unit that determines whether each of the temperatures of a predetermined number of consecutive measurement locations among the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference, and a defective seal detection unit that detects that a defective seal has occurred in the package if the first determination unit determines that any of the temperatures of the plurality of measurement locations is not within the predetermined temperature range or if the second determination unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference.

[0010] The inventors considered the state of defective sealing when sealing a package by heating. First, they noticed that defective sealing occurs even when the measured temperature of the sealed portion is within a preset temperature range. They then found that simply determining whether the temperature is within the preset temperature range is not sufficient to detect defective sealing. After further intensive research, the inventors discovered that when a foreign object, especially a small amount of powder, is trapped in the sealed portion, the temperature changes slightly from the temperature before and after measurement. With further ingenuity, the inventors came up with the idea that if a small temperature change is observed at a certain measurement point among a predetermined number of consecutive measurement points, even if the temperature is within the preset temperature range, a defective sealing has occurred due to the trapped foreign object, etc., and this led to the construction of the present invention.

[0011] According to the seal defect detection system of the present disclosure, if the first determination unit determines that the temperature is not within a predetermined temperature range, a seal defect is detected. Furthermore, if the second determination unit determines that the temperatures of a predetermined number of consecutive measurement locations among the plurality of measurement locations are each greater than a predetermined first temperature difference, a seal defect is also detected. This allows for detection of seal defects caused by foreign matter or the like, even when the temperatures of the measurement locations are within the predetermined temperature range, using a determination based on the first temperature difference. In this case, seal defects are detected based on the temperatures of multiple measurement locations continuously measured by the temperature measurement unit, eliminating the need for visual inspection and eliminating the influence of the pattern or color of the package. Therefore, the presence or absence of a seal defect can be determined more efficiently. As described above, the seal defect detection system described above allows for accurate and efficient detection of whether a seal defect has occurred.

[0012] The above-described seal defect detection system may further include a third determination unit that determines whether a difference between a maximum temperature and a minimum temperature among the temperatures at the plurality of measurement locations is equal to or less than a predetermined second temperature difference. The seal defect detection unit may detect that a seal defect has occurred in the package if the third determination unit determines that the difference between the maximum temperature and the minimum temperature among the temperatures at the plurality of measurement locations is greater than the predetermined second temperature difference.

[0013] The inventors have found that when a package is properly sealed, i.e., when no sealing defects have occurred, the difference between the maximum and minimum temperatures at all measurement locations often falls within a predetermined range. In other words, the inventors have further discovered that if the difference between the maximum and minimum temperatures falls outside the predetermined range, there is a high possibility that a sealing defect has occurred. According to the above-described sealing defect detection system, if the third judgment unit judges that the difference between the maximum and minimum temperatures among the temperatures at the multiple measurement locations is greater than the second temperature difference, the package has detected the occurrence of a sealing defect, making it possible to detect with greater accuracy whether a sealing defect has occurred.

[0014] The above-mentioned seal defect detection system may further include a notification control unit that controls the notification of the detection result by the seal defect detection unit. In this way, the user can easily understand that a seal defect has occurred in the package by the notification control unit using, for example, a visual or auditory notification. In this way, the notification result by the notification control unit can be used to adjust or control the sealing device to make seal defects less likely to occur. Therefore, convenience can be further improved.

[0015] In the above-described seal defect detection system, the temperature measurement unit may measure the temperature at multiple measurement locations while the package is moving. This allows the temperature measurement unit to measure the temperature at a fixed location, thereby more accurately measuring the temperature of the sealed area of ​​the package. Furthermore, this makes it easier to incorporate the system into intermediate processes as the package is moved on the production line, thereby improving productivity.

[0016] In the above-described seal defect detection system, the temperature measurement unit may measure the temperature of multiple measurement points in the seal area in a non-contact manner. This allows for more efficient and stable temperature measurement of the measurement points, thereby enabling more accurate detection of seal defects.

[0017] In the above-described seal defect detection system, the measurement speed by the temperature measurement unit may be 1.5 m (milliseconds) or less per measurement. This allows the number of measurements by the temperature measurement unit to be sufficiently increased, greatly reducing the risk of missing a seal defect in a location where a small amount of foreign matter has been trapped. Therefore, it is possible to more reliably determine whether or not a seal defect has occurred.

[0018] In the above-described sealing defect detection system, the notification control unit may be controlled to notify the user by displaying a message indicating that a sealing defect has occurred on the display. By doing so, the user can understand that a sealing defect has occurred by looking at the screen displayed on the display. Therefore, the user can visually recognize that a sealing defect has occurred more easily.

[0019] In the above-described sealing defect detection system, the notification control unit may be controlled to notify the sealing defect detection unit if it does not detect that a sealing defect has occurred. This makes it easy to know that no sealing defect has occurred in the sealing process, thereby improving work efficiency.

[0020] In the above-described seal defect detection system, the notification control unit may control the display of a graph showing the relationship between the temperature at the plurality of measurement locations acquired by the temperature acquisition unit and the elapsed time. In this way, the relationship between the temperature transition over the measurement time and the elapsed time shown in the graph can be visually and easily grasped, and it can be easily recognized whether the seal defect detection unit's judgment of the seal defect detection is normal or not.

[0021] In the above-described seal defect detection system, the seal defect detection unit may detect that the seal defect has occurred due to a foreign object being trapped in the sealing area if the second determination unit determines that each of the temperatures at a predetermined number of consecutive measurement locations is greater than the first temperature difference and is higher than the temperatures at the consecutive measurement locations. This makes it easy to recognize that the cause of the seal defect is the presence of a foreign object. Therefore, it becomes easier to take measures against the seal defect, such as reducing the risk of foreign object being trapped.

[0022] In the above-described sealing defect detection system, the sealing defect detection unit may detect that a sealing defect has occurred due to tilting of the sealing area from the temperature change acquired by the temperature acquisition unit. In this way, it is possible to easily recognize that the cause of the sealing defect is due to tilting of the sealing area based on the acquired temperature change. This makes it easier to take measures to address the sealing defect, such as correcting the angle of the package before sealing to correct the tilt of the sealing area.

[0023] In the above-described sealing defect detection system, the sealing defect detection unit may detect that a sealing defect has occurred due to the occurrence of wrinkles in the sealing area if the first determination unit determines that all measurement points except the first and last measurement points among the multiple measurement points are not within a predetermined temperature range and are lower than the temperatures of the consecutive measurement points. This makes it easy to determine that the cause of the sealing defect is the occurrence of wrinkles (gathers) in the sealing area. This makes it easier to take measures to address the sealing defect, such as thoroughly removing static electricity from the package before sealing.

[0024] The defective seal detection method of the present disclosure is a method for detecting defective seals in a package sealed by heating, and includes a temperature measurement step of sequentially measuring the temperatures of multiple measurement points in a sealed area sealed along the width direction of the seal; a temperature acquisition step of acquiring the temperatures of the multiple measurement points measured by the temperature measurement step; a first judgment step of determining whether any of the temperatures of the multiple measurement points acquired by the temperature acquisition step is within a predetermined temperature range in which an upper temperature limit and a lower temperature limit are set in advance; a second judgment step of determining whether each of the temperatures of a predetermined number of consecutive measurement points among the temperatures of the multiple measurement points acquired by the temperature acquisition step is equal to or less than a predetermined first temperature difference; and a defective seal detection step of detecting that a defective seal has occurred in the package if the first judgment step determines that any of the temperatures of the multiple measurement points is not within the predetermined temperature range or the second judgment step determines that each of the temperatures of the predetermined number of consecutive measurement points is greater than the first temperature difference.

[0025] According to this method for detecting a defective seal, it is possible to accurately and efficiently detect whether or not a defective seal has occurred.

[0026] The above-mentioned seal defect detection method may further include a third determination step of determining whether or not a difference between a maximum temperature and a minimum temperature among the temperatures at the plurality of measurement locations is equal to or less than a predetermined second temperature difference. The seal defect detection step may detect that a seal defect has occurred in the package if it is determined by the third determination step that the difference between the maximum temperature and the minimum temperature among the temperatures at the plurality of measurement locations is greater than the predetermined second temperature difference.

[0027] By doing so, it is possible to detect with higher accuracy whether or not a sealing defect has occurred.

[0028] [Specific example of embodiment] Next, an example of a specific embodiment of the seal defect detection system of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0029] (Embodiment 1) The configuration of a seal defect detection system according to a first embodiment of the present disclosure will be described. Fig. 1 is a block diagram showing a schematic configuration of the seal defect detection system according to the first embodiment. Fig. 2 is a schematic perspective view showing the appearance of a sealing device and a portion of the seal defect detection system shown in Fig. 1. Fig. 3 is a schematic diagram showing an example of a control panel included in the sealing device. Fig. 4 is a schematic enlarged view showing the vicinity of the input opening, which is the sealing area of ​​a sealed package.

[0030] 1, 2, 3, and 4, a seal defect detection system 11 according to a first embodiment detects seal defects in a package 12 sealed by heating. A sealing device 13 is used to seal the package 12. The sealing device 13 includes a heater bar 14 that heats the package 12 to a temperature at which the package 12 can be welded, and a control panel 15 having a display 16 and used to control the sealing device 13. The sealing device 13 seals an inlet 17, which is an opening of the package 12, by heating. Specifically, after a predetermined amount of powder material is placed inside the package 12, the package 12 is transported to an area where the heater bar 14 is located. The heater bar 14 is then pressed against a sealing area 18, which is an area of ​​the inlet 17 to be sealed, and the package 12 is sealed by heating it. The sealing area 18 is located in an area near the end of the package 12 where the inlet 17 is located. The package 12 is made of a resin that can be welded by heating, specifically, a polyolefin film. In this embodiment, we will explain the case where the contents put into the packaging body 12 are powdery, but the contents are not limited to powdery, and may be, for example, liquid or granular, or simply solid.

[0031] The seal defect detection system 11 includes a radiation thermometer 21 as a temperature measurement unit, and a seal defect detection device 22. The radiation thermometer 21 sequentially measures the temperature at multiple measurement points in the sealed area 18 sealed along the width direction of the seal. The width direction of the seal is the direction indicated by arrow D in FIG. 4. The radiation thermometer 21 measures the temperature of an area including a fixed point in the sealed area 18 while moving the package 12, thereby measuring the temperature at multiple measurement points in a non-contact manner. Specifically, the radiation thermometer 21 is attached to a part of the sealing device 13 and fixed in a position where it can periodically measure the sealed area 18 of the package 12 being conveyed by the sealing device 13.

[0032] FIG. 5 is a diagram showing an example of measurement points in the sealing area 18. In FIG. 5, multiple measurement points 19A, 19B, 19C, and 19D are shown as hatched areas. Also, in FIG. 5, the sealing area 18 is shown by a dashed line. For ease of understanding, FIG. 5 shows only measurement points 19A, 19B, 19C, and 19D. However, in reality, there are many more measurement points, and they are arranged more continuously, i.e., the circled measurement points are arranged so that their positions are slightly shifted. Also referring to FIG. 5, the radiation thermometer 21 measures the temperatures of measurement points 19A to 19D in sequence along the direction indicated by arrow D in FIG. 5. In this embodiment, the start point of the measurement points is measurement point 19A, and the end point of the measurement points is measurement point 19D. The measurement speed by the radiation thermometer 21 is 1.5 ms or less. That is, the time required for each measurement by the radiation thermometer 21 is 1.5 ms or less. From the viewpoint of sufficiently improving the measurement accuracy and optimizing the amount of information required for processing, the measurement speed by the radiation thermometer 21 is preferably 0.7 msec or more and 1.5 msec or less. In this embodiment, the measurement speed by the radiation thermometer 21 is 1 msec / time.

[0033] Next, the configuration of the seal defect detection device 22 will be described. The seal defect detection device 22 includes a seal defect detection device interface unit 24 for connecting the seal defect detection device 22 to external devices, a seal defect detection device control unit 25 for controlling the seal defect detection device 22 itself, and a seal defect detection device memory unit 26 for storing data in the seal defect detection device 22. The seal defect detection device 22 is primarily composed of a PLC (Programmable Logic Controller) having a CPU (Central Processing Unit). The seal defect detection device interface unit 24 is connected to the radiation thermometer 21 and the sealing device 13 via a wired or wireless connection and functions as a transmitter for transmitting data and a receiver for receiving data. In this embodiment, the seal defect detection device memory unit 26 is composed of a memory area within the PLC's CPU and stores data such as temperature data received from the radiation thermometer 21 by the receiver. The seal defect detection device memory unit 26 may be a non-volatile memory built into the seal defect detection device 22 or an external hard disk.

[0034] The defective seal detection device control unit 25 is composed of a CPU and the like, and includes a temperature acquisition unit 27, a first determination unit 31, a second determination unit 32, a third determination unit 33, a defective seal detection unit 34, and a notification control unit 35. The temperature acquisition unit 27 acquires temperatures at multiple measurement locations measured by the radiation thermometer 21. The defective seal detection device interface unit 24 is used to acquire the temperatures. The first determination unit 31 determines whether any of the temperatures at the multiple measurement locations acquired by the temperature acquisition unit 27 is within a predetermined temperature range with preset upper and lower limits. The second determination unit 32 determines whether each of the temperatures at a predetermined number of consecutive measurement locations acquired by the temperature acquisition unit 27 is equal to or less than a predetermined first temperature difference. The third determination unit 33 determines whether the difference between the maximum and minimum temperatures at the multiple measurement locations is equal to or less than a predetermined second temperature difference. The seal defect detection unit 34 detects that a seal defect has occurred in the package 12 if the first judgment unit 31 judges that any of the temperatures at the multiple measurement locations is not within a predetermined temperature range, or if the second judgment unit 32 judges that each of the temperatures at a predetermined number of consecutive measurement locations is greater than a first temperature difference. Furthermore, the seal defect detection unit 34 detects that a seal defect has occurred in the package 12 if the third judgment unit 33 judges that the difference between the maximum and minimum temperatures among the temperatures at the multiple measurement locations is greater than a preset second temperature difference. The notification control unit 35 controls to notify the detection result by the seal defect detection unit 34. These configurations will be described in detail later.

[0035] Predetermined information is displayed on the display 16. The display 16 is a touch panel type. That is, information can be input by touching the screen. Here, the display on the display 16 will be described. Fig. 6 is an enlarged view of the display 16 shown in Fig. 3. 6, the upper area of ​​display 16 displays various data, such as a "Seal Temperature Trend Graph" indicator 41, an indicator 42A indicating that inspection for seal defects is in progress, a clickable button 42B that transitions to a screen displaying the history of seal defects, an indicator 42C indicating that the currently detected seal is normal, an indicator 43A indicating the cumulative number of packages 12 with normal seals and a numerical value below it, an indicator 43B indicating the cumulative number of packages 12 with improper seals, i.e., defective seals, an indicator 43C indicating the "Yield" and a numerical value below it, indicating the percentage of packages 12 with normal seals relative to the total number of packages, an indicator 44A including an arrow visually indicating the start position of the measurement, and an indicator 44B including an arrow visually indicating the end position of the measurement. A graph 45A showing the progress of the measured temperature is displayed in the central area of ​​display 16. The vertical axis of graph 45A represents the measured temperature (° C.), and the horizontal axis of graph 45A represents the elapsed time (msec).In addition, the lower area of ​​the display 16 displays the words "measurement time" indicating the measurement time for temperature measurement and a numerical value below it 46A, the words "start delay" indicating a delay in the start of temperature measurement and a numerical value below it 46B, the words "test start point" indicating the timing of the start of the test and a numerical value below it 46C, the words "test end point" indicating the timing of the end of the test and a numerical value below it 46D, the words "upper limit temperature" indicating the upper limit temperature of a predetermined temperature range that has been set in advance and a numerical value below it 46E, The following are displayed: "Lower Limit Temperature" and a numerical display 46F indicating the upper limit temperature; "Determination Section" and a numerical display 46G indicating the determination section for the section temperature difference (the first temperature difference), i.e., the predetermined number of consecutive measurement locations; "Section Temperature Difference" and a numerical display 46H indicating the section temperature difference (the first temperature difference); "Total Temperature Difference" and a numerical display 46I indicating the total temperature difference (the second temperature difference); and "Scan Time Adjustment" and a numerical display 46J indicating the adjusted scan time. Specifically, the display 16 indicates that the upper limit temperature is 115°C, the lower limit temperature is 82°C, the determination section is 15, the section temperature difference is 7.0°C, and the total temperature difference is 13.0°C. Specific processing using these items will be described in detail later.

[0036] Next, a method for detecting a seal defect using the seal defect detection system 11 in this embodiment will be described. Fig. 7 is a flowchart showing typical steps when detecting a seal defect using the seal defect detection system 11.

[0037] Referring also to FIG. 7, first, the packaging body 12 containing the powdery material is sealed by the sealing device 13. Then, as a temperature measurement step, the temperature of measurement points 19A to 19D in the sealed area 18 of the sealed packaging body 12 is measured by the radiation thermometer 21 (step S11 in FIG. 7; hereinafter, "step" will be omitted). The measurement speed by the radiation thermometer 21 is 1.5 ms or less. In this embodiment, it is 1 ms. Then, as a temperature acquisition step, the temperatures of the measurement points 19A to 19D measured by the radiation thermometer 21 are acquired by the temperature acquisition unit 27 included in the seal defect detection device control unit 25 of the seal defect detection device 22 via the seal defect detection device interface unit 24, etc. (S12). The temperature measurement of the measurement points is performed continuously at a plurality of measurement points in the sealed area 18 sealed along the width direction of the seal (the direction indicated by arrow D in FIG. 5). The temperature data of the measurement points thus obtained is stored in the seal defect detection device storage unit 26 together with the data of the measurement points.

[0038] Thereafter, the seal defect detection device control unit 25 determines whether or not the temperatures of all measurement points in the seal area 18 of the package 12 have been acquired (S13). The radiation thermometer 21 repeatedly measures the temperature and the temperature acquisition unit 27 repeatedly acquires the temperature until the temperatures of all measurement points have been acquired.

[0039] If the seal defect detection device control unit 25 determines that the temperatures of all measurement locations have been acquired (YES in S13), it is determined that temperature measurement of all measurement locations in the sealing area 18 of one package 12 has been completed. Then, various determinations are made to determine whether or not a seal defect has occurred. In this embodiment, first, as a third determination step, the third determination unit 33 determines whether or not the difference between the maximum temperature and the minimum temperature among the temperatures of the multiple measurement locations is equal to or less than a preset second temperature difference (S14). In this embodiment, 13.0°C is selected as the total temperature difference, which is the second temperature difference, as shown in FIG. 6.

[0040] If the third determination unit 33 determines that the difference between the maximum and minimum temperatures among the temperatures at the plurality of measurement locations is equal to or less than the second preset temperature difference (YES in S14), then the first determination unit 31 determines whether the acquired temperatures at the measurement locations are within a predetermined temperature range in which upper and lower limit temperatures are preset (S15), as a first determination step. In this embodiment, as shown in FIG. 6, a value of 115°C is selected as the preset upper limit temperature, and a value of 82°C is selected as the preset lower limit temperature.

[0041] If the first determination unit 31 determines that the temperatures at the measurement locations obtained are within a predetermined temperature range (YES in S15), then in the second determination step, the second determination unit 32 determines whether the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the multiple measurement locations are equal to or less than a preset first temperature difference (S16). In this embodiment, 7.0°C is selected as the interval temperature difference, which is the first temperature difference, as shown in Figure 6.

[0042] If the second determination unit 32 determines that the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the multiple measurement locations are equal to or less than the preset first temperature difference (YES in S16), the sealing defect detection unit 34 does not detect that a sealing defect has occurred, as a sealing defect detection step. In other words, it detects that the sealing has been performed normally. The notification control unit 35 notifies that the sealing has been performed normally as a detection result by the sealing defect detection unit 34, as a notification control step (S17). Specifically, the word "normal" is displayed on the display 16. An example of a graph 45A in the case of normal sealing is shown in FIG. 6.

[0043] In addition, if the third determination unit 33 does not determine in S14 that the difference between the maximum temperature and the minimum temperature among the temperatures at the plurality of measurement locations is equal to or less than a preset second temperature difference (NO in S14), the sealing defect detection unit 34 detects that a sealing defect has occurred (S18), as a sealing defect detection step. Also, even if the determination in S14 is YES, if the first determination unit 31 does not determine in S15 that the temperatures at the measurement locations acquired are within a predetermined temperature range (NO in S15), that is, if the first determination unit 31 determines that the temperatures at the measurement locations acquired are not within a predetermined temperature range, such as being higher than an upper limit temperature or lower than a lower limit temperature, the sealing defect detection unit 34 also detects that a sealing defect has occurred in this case (S18), as a sealing defect detection step. Even if the determination in S15 is YES, if the second determination unit 32 does not determine in S16 that the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations are equal to or less than the preset first temperature difference (NO in S16), the sealing defect detection unit 34 also detects that a sealing defect has occurred in this case (S18), as a sealing defect detection step. Then, the notification control unit 35 notifies the user that a sealing defect has occurred as a result of detection by the sealing defect detection unit 34 (S19), as a notification control step. Specifically, the notification control unit 35 controls the display 16 to display an indication that a sealing defect has occurred, for example, "abnormal." Note that the notification control unit 35 may not only notify the user by displaying an indication on the display 16, but may also notify the user by flashing a light or by using an auditory or tactile device such as a buzzer or vibration.

[0044] In this embodiment, when a sealing defect is detected, an NG signal is sent to the sealing device 13. When the sealing device 13 receives the NG signal, it uses an NG product discharge mechanism provided on the sealing device 13 side to automatically discharge the defective sealed product, i.e., the NG product, out of the line, i.e., into a lane different from that for OK products. In this way, the sealing of the packages 12 continues without stopping the production line.

[0045] FIG. 8 is a diagram showing an example of what the display 16 shows when a relatively large amount of powdery foreign matter has become trapped, causing a sealing failure. FIG. 9 is a schematic diagram of the sealing area 18 when a relatively large amount of powdery foreign matter has become trapped. Referring to both FIGS. 8 and 9, even when a large amount of powdery matter 51 has become trapped in the sealing area 18 at the position indicated by the hollow arrow V1 in the figure, graph 45B shows that the temperature at the measurement point in the sealing area 18 is within a predetermined temperature range. In other words, the first judgment unit 31 alone cannot detect a sealing failure and the sealing area 18 is determined to be normal. However, at the position indicated by the hollow arrow V1, the second judgment unit 32 determines that the temperature at a predetermined number of consecutive measurement points among the multiple measurement points is greater than the predetermined first temperature difference, thereby detecting the occurrence of a sealing failure.

[0046] FIG. 10 shows an example of what the display 16 shows when a relatively small amount of powdery foreign matter has become trapped, causing a sealing failure. FIG. 11 is a schematic diagram of the sealing area 18 with a relatively small amount of powdery foreign matter trapped. FIG. 11 also shows an enlarged view of the area where the small amount of powdery matter has become trapped. Referring to FIGS. 10 and 11 together, when a small amount of powdery matter 52 has become trapped in the sealing area 18 at the position indicated by the white arrow V2 in the figure, graph 45C shows that the temperature at the measurement point in the sealing area 18 is within the predetermined temperature range, as in the cases shown in FIGS. 8 and 9 above. That is, in this case, the first judgment unit 31 alone cannot detect the sealing failure and the sealing area 18 is determined to be normal. However, at the position indicated by the white arrow V2, the second judgment unit 32 determines that the temperature at a predetermined number of consecutive measurement points among the multiple measurement points is greater than the predetermined first temperature difference, thereby detecting the occurrence of a sealing failure.

[0047] The defective sealing detection unit 34 may detect that a defective seal has occurred due to tilting of the sealing area 18 from the transition of the temperature acquired by the temperature acquisition unit 27. Specifically, this is detected from the shape of the graph shown on the display 16. By doing so, it is possible to easily recognize that the cause of the defective seal is due to tilting of the sealing area 18, based on the transition of the acquired temperature. This makes it easier to take measures to address the defective seal, such as correcting the tilt of the sealing area 18 by correcting the misalignment of the angle of the package 12 before sealing.

[0048] FIG. 12 is a diagram showing an example of what is displayed on display 16 when a seal is tilted, causing a sealing failure. FIG. 13 is a schematic diagram of sealing area 18 when the seal is tilted. In FIG. 13, the dashed line shows a graph for when the seal is not tilted. Referring to both FIGS. 12 and 13, if sealing area 18 is tilted due to, for example, an error during transport of package 12, graph 45D shows that the temperature at the measurement point gradually increases at the beginning of measurement. Furthermore, it takes a long time for the temperature to reach the minimum temperature after measurement begins. From the shape of graph 45D, which is based on the transition of the temperature acquired by temperature acquisition unit 27, it is possible to detect that a sealing failure has occurred due to tilting of sealing area 18.

[0049] Fig. 14 is a diagram showing an example of what is displayed on display 16 when wrinkles (gathers) have occurred in sealing area 18, causing a sealing failure. Fig. 15 is a schematic diagram of sealing area 18 in a state where wrinkles have occurred in sealing area 18. Referring to Figs. 14 and 15, if wrinkles 53 have occurred in area 54 of sealing area 18, indicated by a white arrow V3 in the figure, due to, for example, an error during transport of packaging body 12, according to graph 45E, if first determination unit 31 determines that the temperature is not within the predetermined temperature range and is lower than the temperatures of consecutive measurement points, it can be detected that wrinkles 53 have occurred in sealing area 18 and that a sealing failure has occurred.

[0050] As described above, with this seal defect detection system 11, if the first determination unit 31 determines that the temperature is not within a predetermined temperature range, a seal defect is detected. Furthermore, if the second determination unit 32 determines that each of the temperatures at a predetermined number of consecutive measurement locations among the plurality of measurement locations is greater than a predetermined first temperature difference, a seal defect is also detected. This allows for detection of seal defects caused by the inclusion of foreign matter, etc., using a determination based on the first temperature difference, even when the temperatures at the measurement locations are within the predetermined temperature range. In this case, because seal defects are detected based on the temperatures of multiple measurement locations continuously measured by the radiation thermometer 21, visual inspection is not required, and the influence of the pattern or color of the package 12 can be eliminated. Therefore, the presence or absence of a seal defect can be determined more efficiently. As described above, it is possible to accurately and efficiently detect whether a seal defect has occurred.

[0051] In this embodiment, a third determination unit 33 is included that determines whether the difference between the maximum temperature and the minimum temperature among the temperatures at the multiple measurement locations is equal to or less than a preset second temperature difference. If the third determination unit 33 determines that the difference between the maximum temperature and the minimum temperature among the temperatures at the multiple measurement locations is greater than the preset second temperature difference, the seal defect detection unit 34 detects that a seal defect has occurred in the package 12.

[0052] According to the above-mentioned sealing defect detection system 11, if the third judgment unit 33 judges that the difference between the maximum temperature and the minimum temperature among the temperatures at multiple measurement points is greater than the second temperature difference, the packaging body 12 has detected the occurrence of a sealing defect, and therefore it is possible to detect with greater accuracy whether or not a sealing defect has occurred.

[0053] In this embodiment, the seal defect detection system 11 includes a notification control unit 35 that controls the notification to notify the detection result by the seal defect detection unit 34. Therefore, the user can easily understand that a seal defect has occurred in the package 12 by the notification by the notification control unit 35, for example, visually or audibly. In this way, the notification result by the notification control unit 35 can be used to adjust or control the sealing device 13, making it less likely that a seal defect will occur. This can further improve convenience.

[0054] In this embodiment, the radiation thermometer 21 measures the temperature at a plurality of measurement points while moving the packaging body 12. Therefore, the radiation thermometer 21 can measure the temperature at a fixed point, and can more appropriately measure the temperature of the sealed area of ​​the packaging body 12. Furthermore, this makes it easier to incorporate the radiation thermometer 21 into an intermediate process when the packaging body 12 is being moved on the production line, thereby improving productivity.

[0055] In this embodiment, the radiation thermometer 21 measures the temperature at a plurality of measurement points in the seal area 18 in a non-contact manner. This allows the temperature at the measurement points to be measured more efficiently and stably. This allows for more accurate detection of sealing defects.

[0056] In this embodiment, the measurement speed by the radiation thermometer 21 is 1.5 ms / time or less. Therefore, by sufficiently increasing the number of measurements by the radiation thermometer 21, it is possible to significantly reduce the risk of overlooking a sealing defect at a location where a minute foreign object has been caught. Therefore, it is possible to more reliably determine whether or not a sealing defect has occurred.

[0057] In this embodiment, the notification control unit 35 controls the display 16 to notify the user that a sealing defect has occurred by displaying a message indicating this. This allows the user to understand that a sealing defect has occurred by looking at the screen displayed on the display. This makes it easier to visually recognize that a sealing defect has occurred.

[0058] In this embodiment, the notification control unit 35 controls the sealing defect detection unit 34 to notify the user that a sealing defect has not occurred if the sealing defect detection unit 34 does not detect that a sealing defect has occurred. This makes it easy to know that no sealing defect has occurred in the sealing process, thereby improving work efficiency.

[0059] In this embodiment, the notification control unit 35 controls the display of a graph showing the relationship between the temperature at a plurality of measurement locations acquired by the temperature acquisition unit 27 and the elapsed time. This allows the user to visually and easily grasp the relationship between the temperature transition over the measurement time and the elapsed time, and to easily recognize whether the seal defect detection unit 34 has correctly detected the seal defect.

[0060] In this embodiment, if the second determination unit 32 determines that each of the temperatures at a predetermined number of consecutive measurement locations is greater than the first temperature difference and is higher than the temperatures at the consecutive measurement locations, the seal defect detection unit 34 detects that a seal defect has occurred due to a foreign object being caught in the sealing area 18. This makes it easy to recognize that the cause of the seal defect is the presence of a foreign object. This makes it easier to take measures against the seal defect, such as reducing the risk of a foreign object being caught.

[0061] In this embodiment, if the first determination unit 31 determines that all measurement points except the first and last measurement points among the multiple measurement points are not within a predetermined temperature range and are lower than the temperatures of the successive measurement points, the sealing defect detection unit 34 detects that a sealing defect has occurred due to the occurrence of wrinkles in the sealing area 18. This makes it easy to recognize that the cause of the sealing defect is the occurrence of wrinkles (gathers) in the sealing area. This makes it easier to take measures to prevent sealing defects, such as sufficiently removing static electricity from the package before sealing.

[0062] In addition, the sealing defect detection method of the present disclosure is a sealing defect detection method for detecting sealing defects in a package 12 sealed by heating, and includes a temperature measurement process for sequentially measuring the temperatures of multiple measurement points in a seal area 18 sealed along the width direction of the seal; a temperature acquisition process for acquiring the temperatures of the multiple measurement points measured by the temperature measurement process; a first judgment process for determining whether any of the temperatures of the multiple measurement points acquired by the temperature acquisition process are within a predetermined temperature range in which upper and lower limit temperatures are set in advance; a second judgment process for determining whether each of the temperatures of a predetermined number of consecutive measurement points among the temperatures of the multiple measurement points acquired by the temperature acquisition process is equal to or less than a predetermined first temperature difference; and a sealing defect detection process for detecting that a sealing defect has occurred in the package 12 if the first judgment process determines that any of the temperatures of the multiple measurement points is not within the predetermined temperature range or if the second judgment process determines that each of the temperatures of the predetermined number of consecutive measurement points is greater than the first temperature difference.

[0063] According to this method for detecting a defective seal, it is possible to accurately and efficiently detect whether or not a defective seal has occurred.

[0064] The above-described seal defect detection method may further include a third determination step of determining whether the difference between the maximum temperature and the minimum temperature among the temperatures at the plurality of measurement locations is equal to or less than a predetermined second temperature difference. The seal defect detection step may detect that a seal defect has occurred in the package 12 if it is determined by the third determination step that the difference between the maximum temperature and the minimum temperature among the temperatures at the plurality of measurement locations is greater than the predetermined second temperature difference.

[0065] By doing so, it is possible to detect with higher accuracy whether or not a sealing defect has occurred.

[0066] (Other embodiments) In the above embodiment, the temperature measurement unit measures the temperature at multiple measurement points in the seal area without contacting the seal area. However, this is not limited to this, and the temperature measurement unit may measure the temperature by contacting the seal area. Furthermore, while the temperature measurement unit measures the temperature at multiple measurement points while moving the package, this is not limited to this, and the temperature measurement unit may measure the temperature at multiple measurement points in the seal area by moving the measurement points of the radiation thermometer.

[0067] In the above embodiment, the sealing device 13 may be included in the seal defect detection system 11. In addition to control by a control panel, control may be performed from a mobile terminal device such as a laptop PC or a smartphone.

[0068] In the above embodiment, the determination by the third determination unit is followed by the determination by the first determination unit, and then the determination by the second determination unit. However, this is not limiting, and the order of the determinations by the first determination unit, second determination unit, and third determination unit does not matter. That is, for example, the determination by the first determination unit may be made first, then the determination by the second determination unit, and finally the determination by the third determination unit. Alternatively, the determination by the first determination unit may be made first, then the determination by the third determination unit, and finally the determination by the second determination unit. Alternatively, the determination by the second determination unit may be made first, then the determination by the first determination unit, and finally the determination by the third determination unit. Alternatively, the determination by the second determination unit may be made first, then the determination by the third determination unit, and finally the determination by the first determination unit. Alternatively, the determination by the third determination unit may be made first, then the determination by the second determination unit, and finally the determination by the first determination unit. Alternatively, the determination by the third determination unit may be made first, then the determination by the second determination unit, and finally the determination by the first determination unit.

[0069] The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention. [Explanation of symbols]

[0070] 11 Sealing defect detection system, 12 Packaging body, 13 Sealing device, 14 Heater bar, 15 Control panel, 16 Display, 17 Input port, 18 Sealing area, 19A, 19B, 19C, 19D Measurement location, 21 Radiation thermometer, 22 Sealing defect detection device, 24 Sealing defect detection device interface unit, 25 Sealing defect detection device control unit, 26 Sealing defect detection device memory unit, 27 Temperature acquisition unit, 31 First judgment unit, 32 Second judgment unit, 33 Third judgment unit, 34 Sealing defect detection unit, 35 Notification control unit, 41, 42A, 42C, 43A, 43B, 43C, 44A, 44B, 46A, 46B, 46C, 46D, 46E, 46F, 46G, 46H, 46I, 46J Display, 42B Buttons, 45A, 45B, 45C, 45D, 45E Graphs, 51, 52 Powder, 53 Wrinkles, 54 Area.

Claims

1. A seal defect detection system for detecting seal defects in a package sealed by heating, comprising: a temperature measuring unit that sequentially measures the temperature of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition unit that acquires temperatures of the plurality of measurement points measured by the temperature measurement unit; a first determination unit that determines whether any of the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination unit that determines whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference; a third determination unit that determines whether a difference between a maximum temperature and a minimum temperature among the temperatures at the plurality of measurement points is equal to or less than a second temperature difference that is set in advance; a seal defect detection unit that detects that a seal defect has occurred in the package when the first determination unit determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or when the second determination unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The seal defect detection system detects that a seal defect has occurred in the package if the third judgment unit determines that the difference between the maximum temperature and the minimum temperature among the temperatures of the multiple measurement locations is greater than the predetermined second temperature difference.

2. A seal defect detection system for detecting seal defects in a package sealed by heating, comprising: a temperature measuring unit that sequentially measures the temperature of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition unit that acquires temperatures of the plurality of measurement points measured by the temperature measurement unit; a first determination unit that determines whether any of the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination unit that determines whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference; a seal defect detection unit that detects that a seal defect has occurred in the package when the first determination unit determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or when the second determination unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The seal defect detection system detects that the seal defect has occurred due to a foreign object being caught in the sealing area if the second judgment unit judges that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference and is higher than the temperature of the consecutive measurement locations.

3. A seal defect detection system for detecting seal defects in a package sealed by heating, comprising: a temperature measuring unit that sequentially measures the temperature of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition unit that acquires temperatures of the plurality of measurement points measured by the temperature measurement unit; a first determination unit that determines whether any of the temperatures of the plurality of measurement locations acquired by the temperature acquisition unit is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination unit that determines whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired by the temperature acquisition unit is equal to or less than a predetermined first temperature difference; a seal defect detection unit that detects that a seal defect has occurred in the package when the first determination unit determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or when the second determination unit determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The seal defect detection unit detects that the seal defect has occurred due to the occurrence of wrinkles in the seal area if the first judgment unit determines that any of the measurement points other than the first and last measurement points among the plurality of measurement points is not within the specified temperature range and is determined to be lower than the temperature of the consecutive measurement points.

4. The seal defect detection system according to claim 1 , further comprising a notification control unit that controls the detection result by the seal defect detection unit to be notified.

5. The seal defect detection system according to claim 1 , wherein the temperature measurement unit measures the temperatures of the plurality of measurement locations while moving the package.

6. The seal defect detection system according to claim 1 , wherein the temperature measurement unit measures the temperatures of the plurality of measurement points in the seal area in a non-contact manner.

7. 4. The seal defect detection system according to claim 1, wherein the measurement speed of the temperature measurement unit is 1.5 msec or less per measurement.

8. The seal defect detection system according to claim 1 , wherein the seal defect detection unit detects that the seal defect has occurred due to tilting of the seal area from a change in temperature acquired by the temperature acquisition unit.

9. The seal defect detection system according to claim 4 , wherein the notification control unit controls a display to notify the user that the seal defect has occurred by displaying the fact that the seal defect has occurred.

10. The seal defect detection system according to claim 4 , wherein the notification control unit controls the seal defect detection unit to notify the occurrence of the seal defect if the seal defect detection unit does not detect the occurrence of the seal defect.

11. The seal defect detection system according to claim 4 , wherein the notification control unit controls the display unit to graph the relationship between the temperatures at the plurality of measurement locations acquired by the temperature acquisition unit and the elapsed time.

12. A method for detecting seal defects in a package sealed by heating, comprising: a temperature measurement step of sequentially measuring the temperatures of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition step of acquiring temperatures of the plurality of measurement points measured in the temperature measurement step; a first determination step of determining whether any of the temperatures of the plurality of measurement points acquired in the temperature acquisition step is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination step of determining whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired in the temperature acquisition step is equal to or less than a predetermined first temperature difference; a third determination step of determining whether a difference between a maximum temperature and a minimum temperature among the temperatures at the plurality of measurement points is equal to or less than a second predetermined temperature difference; a seal defect detection step of detecting that a seal defect has occurred in the package if the first determination step determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or if the second determination step determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The sealing defect detection method includes detecting that a sealing defect has occurred in the package if the third judgment step determines that the difference between the maximum temperature and the minimum temperature among the temperatures of the plurality of measurement locations is greater than the predetermined second temperature difference.

13. A method for detecting a seal defect in a package sealed by heating, comprising: a temperature measurement step of sequentially measuring the temperatures of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition step of acquiring temperatures of the plurality of measurement points measured in the temperature measurement step; a first determination step of determining whether any of the temperatures of the plurality of measurement points acquired in the temperature acquisition step is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination step of determining whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired in the temperature acquisition step is equal to or less than a predetermined first temperature difference; a seal defect detection step of detecting that a seal defect has occurred in the package if the first determination step determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or if the second determination step determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The sealing defect detection process detects that the sealing defect has occurred due to a foreign object being caught in the sealing area if the second judgment process determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference and is higher than the temperature of the consecutive measurement locations.

14. A method for detecting a seal defect in a package sealed by heating, comprising: a temperature measurement step of sequentially measuring the temperatures of a plurality of measurement points in the sealed area along the width direction of the seal; a temperature acquisition step of acquiring temperatures of the plurality of measurement points measured in the temperature measurement step; a first determination step of determining whether any of the temperatures of the plurality of measurement points acquired in the temperature acquisition step is within a predetermined temperature range in which an upper limit temperature and a lower limit temperature are set in advance; a second determination step of determining whether or not each of the temperatures at a predetermined number of consecutive measurement locations among the temperatures at the plurality of measurement locations acquired in the temperature acquisition step is equal to or less than a predetermined first temperature difference; a seal defect detection step of detecting that a seal defect has occurred in the package if the first determination step determines that any one of the temperatures of the plurality of measurement locations is not within the predetermined temperature range, or if the second determination step determines that each of the temperatures of the predetermined number of consecutive measurement locations is greater than the first temperature difference, The sealing defect detection method includes a step of detecting that the sealing defect has occurred due to wrinkles occurring in the sealing area if the first judgment step determines that all of the measurement points except the first and last measurement points among the plurality of measurement points are not within the predetermined temperature range and are lower than the temperature of the consecutive measurement points.

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