JPH08301241A - Detection device of inferior seal of packaging material - Google Patents

Abstract

PURPOSE: To measure rapidly and stably inferior seals of heat adhesion parts in a packing material like a retort pouch, by setting a specified distance of a pair of electrostatic capacity sensors oppositely arranged at the holding position of the heat adhesion part, to coincide with the distance that a specified figure is added to the heat adhesion part and making each sensor diameter within a specified figure. CONSTITUTION: A pair of electrostatic sensors 320 are fixed at the position to hold the heat adhesion part 105 so as to be oppositely positioned to the opposite metallic member 310 of the measuring part 300 and provided at every specified distance that 0.1-0.2mm is added to the thickness of heat adhesion part 105. The sensor diameter of a pair of electrostatic capacity sensors 320 is made within 0.5-2.0mm to detect the electrostatic capacity generated between these sensor and the conductive layer of the packing material. Accordingly, it is easy to securely guide the heat adhesion part 105 between a pair of electrostatic sensors 320 and also the detecting accuracy of the electrostatic capacity sensor 320 is high and as a result, it can bring out a high detecting accuracy of inferior seals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal defect detecting device for detecting a seal defect at a heat-sealed portion in a packaging material having an item contained therein.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Laid-Open No. 6-3450
The technique disclosed in Japanese Patent No. 62 is known. This technology is a method and a device for detecting a sealing failure of a heat-welded portion of a retort pouch packaging material, in which a capacitance sensor is arranged so as to face a member having a U-shaped cross section and having a U-shaped cross section. The distance to the heat-welded portion passing through the member is measured with a pair of capacitance sensors, from the output measured with the pair of capacitance sensors, the thickness of the heat-welded portion is calculated, and the calculated thickness is
A seal defect is detected when the thickness is larger than a preset thickness.

[0003]

The technique disclosed in the above publication discloses the basic principle for detecting a seal defect in a heat-welded portion, and realistically detects a seal defect in a retort pouch. There is no disclosure of a device that does, and a technique for practical use has been desired.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a packaging material capable of realistically detecting a sealing defect of a heat-welded portion in a packaging material such as a retort pouch. It is to provide a seal defect detection device.

[0005]

The following technical means has been adopted for the device for detecting defective sealing of the packaging material of the present invention. [Means for Claim 1] A device for detecting a sealing failure of a packaging material is a ready-made bag having a conductive layer and a heat-welding layer, and is a moving means for moving the packaging material having an opening heat-welded after containing an inner package therein. And a pair of electrostatic capacitance sensors that are provided in the middle of passage of the packaging material that is moved by the moving means and that are opposed to each other with a predetermined gap at positions sandwiching the heat-sealed heat-welded portion, and the pair of static capacitance sensors. The capacitance sensor is provided with an oscillating circuit for giving an AC voltage of a predetermined frequency and a predetermined frequency, and a voltage measuring means for adding and measuring output voltages of the pair of capacitance sensors, and an output measured by the voltage measuring means. In a seal defect detection device for detecting a seal defect of the heat-welded portion that has passed through the pair of capacitance sensors when the voltage rises above a preset threshold voltage, the predetermined gap is the heat Of welded part Mini, provided the interval plus 0.1 to 0.2 mm, the sensor diameter of said pair of capacitive sensor is characterized in that provided in the range of 0.5 to 2.0 mm.

[Means for Claim 2] In the seal defect detecting device according to claim 1, the response frequency obtained from the predetermined frequency is set to 1 kHz or more.

[Means for Claim 3] The defective seal detecting device is a ready-made bag provided with a conductive layer and a heat-welding layer, and is a moving means for moving a packaging material having an opening heat-welded after containing an inner package therein. And a pair of electrostatic capacitance sensors that are provided in the middle of passage of the packaging material that is moved by the moving means and that are opposed to each other with a predetermined gap at positions sandwiching the heat-sealed heat-welded portion, and the pair of static capacitance sensors. The capacitance sensor is provided with an oscillating circuit for giving an AC voltage of a predetermined frequency and a predetermined frequency, and a voltage measuring means for adding and measuring output voltages of the pair of capacitance sensors, and an output measured by the voltage measuring means. When the voltage rises above a preset threshold voltage, defective sealing of the heat-welded portion that has passed through the pair of capacitance sensors is detected.

[Means of Claim 4] In the seal defect detecting device according to any one of Claims 1 to 3, the pair of capacitance sensors are in the middle of passage of the packaging material moved by the moving means. And is fixed to opposing members having a U-shaped cross section, which are provided to be opposed to each other at a position sandwiching the heat-welded portion with a predetermined gap.

[Means of Claim 5] In the seal defect detecting apparatus according to any one of Claims 1 to 4, the moving means includes an endless belt that sequentially moves the plurality of packaging materials, and A partition for partitioning the packaging material is provided on the surface of the endless belt, and lateral guides that substantially match the width of the packaging material are provided on both sides of the endless belt.

[Means for Claim 6] In the seal defect detecting device according to claim 5, at least the lateral guide on the side for guiding the heat-welded portion toward the pair of electrostatic capacitance sensors is provided with the pair of electrostatic capacitances. It is characterized in that it is provided with a U-shaped cross section for restricting the curvature of the heat-welded portion guided between the sensors within a predetermined range.

[Means for Claim 7] In the device for detecting a seal defect according to any one of claims 1 to 6, the threshold voltage is the thickness of the heat-welded portion before welding and the thickness after the welding. It is characterized in that the voltage value is set due to the difference in thickness.

[Means of claim 8] In the seal defect detecting device according to any one of claims 1 to 7, the output voltage added by the pair of capacitance sensors measured by the voltage measuring means. Are visually displayed by an oscillograph.

[Means of Claim 9] In the defective seal detecting device according to any one of Claims 1 to 8, the threshold voltage is set so as to be manually operable. .

[Means of Claim 10] The seal defect detecting device according to any one of claims 1 to 9 is a detecting means for detecting both ends of the heat-welded portion passing through the pair of capacitance sensors. The voltage measuring means is provided so as not to measure an output voltage when both ends of the heat-welded portion pass through the pair of capacitance sensors.

[Means of Claim 11] In the seal defect detecting device according to any one of Claims 1 to 10, the heat-welded portion guided by the pair of capacitance sensors has high pressure from both sides. It is characterized by being blown with air.

[Means of Claim 12] In the seal defect detecting device according to any one of Claims 1 to 11, the output voltage measured by the voltage measuring means is preset in the moving means. It is characterized by comprising a discharging means for discharging the packaging material having the heat-welded portion, which has passed through the pair of capacitance sensors, from the transport path when the voltage exceeds the threshold voltage.

[Means of Claim 13] The seal defect detecting device according to any one of claims 1 to 12 is arranged to detect a seal defect in a direction orthogonal to a moving direction of the heat-welded portion. The pair of capacitance sensors are provided at a plurality of positions so as not to interfere with each other.

[0018]

Action of the Invention and Effect of the Invention

[Operation and effect of claim 1] If the predetermined gap is provided narrower than the gap obtained by adding 0.1 mm to the thickness of the heat-welded portion,
It becomes difficult to reliably guide the heat-welded portion between the pair of capacitance sensors. In addition, the thickness of the heat welded part is 0.2 mm
If it is provided wider than the interval obtained by adding, the distance between the heat-welded portion and the pair of capacitance sensors becomes long, the detection accuracy of the capacitance sensor deteriorates, and the detection accuracy of the defective seal becomes low.

On the other hand, when the sensor diameter of the pair of capacitance sensors is set smaller than 0.5 mm, the sensor area is small, so that a predetermined sensor accuracy (detection accuracy capable of detecting a seal defect) is obtained. In this case, it is necessary to provide a predetermined gap between the pair of capacitance sensors to be narrower than the gap obtained by adding 0.1 mm to the thickness of the heat-welded portion. It becomes difficult to reliably guide between the electrostatic capacitance sensors. Further, when the sensor diameter of the pair of capacitance sensors is set to be larger than 2.0 mm, the sensor area is large, and therefore the possibility of straddling the defective seal portion increases. If the sensor diameter crosses over the defective seal portion, the voltage measured by the voltage measuring means may not reach the threshold value, and as a result, the accuracy of detecting the defective seal becomes low.

As described above, the predetermined gaps are provided at intervals of 0.1 to 0.2 mm added to the thickness of the heat-welded portion, and the pair of capacitance sensors have a sensor diameter of 0.5 to 2.0 mm. By providing in the range of, it is easy to reliably guide the heat-welded portion between the pair of capacitance sensors, and the detection accuracy of the capacitance sensor is high, resulting in high detection accuracy of the seal failure. Can be demonstrated.

[Operation and Effect of Claim 2] By setting the response frequency obtained from the predetermined frequency of the oscillation circuit to 1 kHz or higher, the detection accuracy of the capacitance sensor is improved. Therefore, even if the moving speed of the packaging material by the moving means is increased, the defective seal can be detected. In this way, even if the moving speed of the moving means is increased, the defective seal can be detected.
It is possible to increase the amount of processing per unit time required for detecting a defective seal.

[Operation and Effect of Claim 3] When the moving means moves the packaging material, the heat-welded portion passes through the pair of capacitance sensors. An AC voltage having a predetermined frequency is applied to the pair of capacitance sensors, and when the heat-welding portions pass through the pair of capacitance sensors, the respective capacitance sensors are heat-welded from the sensor end portions. An output voltage is generated according to the distance to the conductive layer in the section. The outputs of the pair of capacitance sensors are added and measured by the voltage measuring unit. Then, when the heat-welded portion in which the seal defect occurs occurs between the pair of capacitance sensors, the voltage measured by the voltage measurement portion exceeds the threshold value. As described above, when the voltage measured by the voltage measuring unit exceeds the threshold value, it is possible to detect the seal defect.

[Operation and Effect of Claim 4] By fixing the pair of capacitance sensors to the opposing members having a U-shaped cross section through which the heat-welding portion passes, the ends of the heat-welding portion have capacitance. The sensor probe is prevented from being caught, and the heat-welded portion can smoothly pass between the pair of capacitance sensors.

[Operation and Effect of Claim 5] Since the packaging material that moves on the endless belt is regulated by the partition and the lateral guides on both sides, the heat-welded portion of the packaging material can be securely connected to the pair of capacitance sensors. Can be passed between.

[Operation and Effect of Claim 6] A lateral guide for guiding the heat-welded portion to the electrostatic capacity sensor is provided in a U-shaped cross section for restricting the curvature of the heat-welded portion, and the heat-welded portion is provided therein. By passing it, the heat-welded portion of the packaging material can be reliably guided between the pair of capacitance sensors.

[Operation and Effect of Claim 7] The threshold voltage is set to a voltage value caused by the difference between the thickness of the heat-welded portion before welding and the thickness after welding, so that air or a A defective seal can be detected without setting a threshold value by sandwiching a part of the inclusion.

[Operation and Effect of Claim 8] By visually displaying the output voltage measured by the voltage measuring means with an oscillograph, the average value of the thickness of the heat-welded portion can be easily read visually.

[Operation and Effect of Claim 9] By providing the threshold voltage so that it can be manually set,
It is possible to easily set a threshold value for judging a seal failure in accordance with changes in temperature and humidity, or changes in the thickness of the heat-welded portion to be used. In particular, by combining with claim 8, the threshold value can be easily set from the average thickness of the heat-welded portion currently used.

[Operation and Effect of Claim 10] Both ends of the heat-welded portion passing through the pair of capacitance sensors are detected, and in the voltage measuring portion, both ends of the heat-welded portion pass through the pair of capacitance sensors. By not measuring the output voltage at this time, it is possible to eliminate the problem of erroneously detecting a curl generated at the end of the heat-welded portion as a defective seal.

[Operation and Effect of Claim 11] By blowing high-pressure air from both sides to the heat-welded portion guided to the pair of capacitance sensors, liquid such as water adhered to the heat-welded portion, Foreign substances can be removed. For this reason,
It is possible to eliminate the problem of erroneously detecting a defective seal due to a liquid such as water or a foreign substance attached to the heat-welded portion.

[Operation and effect of claim 12] When the output voltage measured by the voltage measuring means exceeds a preset threshold voltage, the packaging material has a heat-welded portion exceeding the threshold voltage. Are discharged from the transportation path by the discharging means. In this way, the packaging material having the defective seal portion is automatically removed from the transport path, so that the work site for detecting the defective seal can be unmanned. It should be noted that it is very effective by unmanning the work site for detecting the defective seal.

[Operation and Effect of Claim 13] By providing a pair of capacitance sensors at a plurality of locations to detect a seal defect in a direction orthogonal to the moving direction of the heat-welded portion,
The accuracy of detecting a seal defect is improved, and the commercial value can be increased.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a sealing defect detecting device for a packaging material according to the present invention will be described based on an embodiment shown in the drawings. [Structure of Embodiment] FIGS. 1 to 10 are for explaining an embodiment adopting the present invention, and FIG. 1 is a schematic view of a sealing defect detecting device for a packaging material. The seal defect detecting device of the present embodiment is one in which a retort product is housed in a packaging material 100, and a moving means 20 utilizing a belt conveyor 201.
0, a measuring unit 300 for detecting a defective seal, and a discharging unit 400 for discharging the defective sealing material 100 when a defective seal is detected.

(Explanation of the packaging material 100)
As shown in FIGS. 2 and 3, a skin layer 101 made of thermoplastic polyester and a conductive layer 10 made of aluminum foil.
2, 3 consisting of a heat-welding layer 103 made of polypropylene
Using a rectangular sheet member 104 in layers, the heat-sealing layers 103 are stacked so as to be directly joined to each other, and a bag-shaped packaging material 100 in which three sides of the four sides are heat-sealed is used. After putting in, the side of the opening is also heat-welded to seal the retort food inside.

Then, in the seal defect detecting apparatus of this embodiment, the heat-welding portion 105 that closes the last heat-welded opening portion is used.
This is to detect a defective seal. The length of the heat-sealed portion 105 on the detection side in this embodiment is 13 cm.

The thickness (thickness before heat welding) obtained by stacking two three-layer sheet members 104 is t1 as shown in FIG. 3A, and the thickness after heat welding is shown in FIG. (B)
The thickness t2 (in this embodiment, for example, 0.2 m
m). That is, the thickness of the heat-welded material is t2, but the thickness of the non-heat-welded material, that is, the thickness of the defective seal is t2 or more.

As will be described later, the seal failure detecting apparatus of the present embodiment utilizes the thickness difference t3 (t3 = t1-t2) between the thickness t1 before welding and the thickness t2 after welding to cause seal failure. Is to detect. The thickness difference t3 in this embodiment is 20 .mu.m. When the thickness difference of 20 μm is converted into a voltage, it becomes about 2V. Therefore, the threshold value of the device of the present invention should be set to 2V.

(Description of moving means 200) Moving means 200
As described above, the belt conveyor 201 is used, and the endless belt 202 of the belt conveyor 201 is a drive device (not shown) such as an electric motor so as to sequentially convey the packaging material 100 mounted on the upper surface. Driven by

As shown in FIG. 4, partitions 203 for partitioning the packaging material 100 one by one are attached to the surface of the endless belt 202 at predetermined intervals.
The partition 203 is preferably a conductive one in view of the detection principle of a capacitance sensor (described later), but may be a non-conductive partition such as urethane. The height of the partition 203 is higher than the height of the packaging material 100 in which the retort food is stored.

In this embodiment, the interval between the partitions 203 is set to 20 cm, the moving speed of the endless belt 202 by the driving device is set to about 43 m / min, and 200 packing materials 100 are packed in one minute. Are provided so as to pass through the measurement unit 300.

The moving means 200 also includes a measuring unit 300.
Unnecessary substance removing means 210 for blowing high-pressure air is provided from both sides of the packaging material 100 before being transported to the inside. This air is blown mainly toward the heat-welded portion 105 that is measured by the measuring unit 300.
It is possible to remove liquids such as water and foreign substances attached to the heat-welded portion 105 guided to 0.

As described above, the unnecessary substance removing means 210 blows high-pressure air onto both sides of the packaging material 100 before being conveyed to the measuring section 300, so that liquid or foreign matter attached to the heat-welding section 105 can be removed. It can be removed, and it is possible to eliminate the problem of erroneously detecting a defective seal due to unnecessary substances attached to the heat-welded portion 105.

On the other hand, on both sides of the endless belt 202, as shown in FIG.
As shown in FIG. 3, the heat-welding portion 1 is provided with a lateral guide 220 that substantially matches the width of the packaging material 100 and detects a sealing failure.
05 is provided so as to reliably pass through the measuring unit 300. The lateral guide 220 of this embodiment uses a processed metal plate formed in a U-shaped cross section, and is provided so that both ends of the packaging material 100 are guided inside the U-shaped cross section. . By being provided in this manner, the curvature of the heat-welded portion 105 that passes through at least the measurement unit 300 is regulated, and the heat-welded portion 105 is smoothly guided to the measurement unit 300. In this embodiment, the lateral guide 220 has a U-shaped cross-section facing distance of 10 mm. The lateral guide 220 is grounded.

(Description of Measuring Unit 300) The measuring unit 300 is
As shown in FIGS. 6 to 8, a metal facing member 310 is provided.
A pair of capacitance sensors 320 fixed to face the facing member 310, an electric circuit 360 having an oscillating circuit 330, a voltage measuring unit 340, and an end measurement cutting unit 350, and the measuring unit 300. The oscillograph 370 visually displays the measured output voltage.

The facing member 310 has a facing distance of 0.35 m.
m (when the thickness of the heat-welded portion 105 is 0.2 mm, 0.1 to 0.
The heat-welded portions 105 of the packaging material 100 guided by the lateral guides 220 are guided into the opposing members by aluminum blocks having a U-shaped cross section provided at an interval of 2 mm added). The facing member 310 is grounded, and the packaging material 1
00 to bring the conductive layer 102 into contact with the conductive layer 10
2 is provided so as to be grounded.

The pair of capacitance sensors 320 are fixed in a state in which they face each other in the opposing member 310 so as to sandwich the heat-welded portion 105, and the capacitance generated between the capacitance sensor 320 and the conductive layer 102 is determined. To detect. The capacitance diameter of the capacitance sensor 320 in this embodiment is 1 mm, and when a seal defect occurs for 1 mm or more,
It is provided so as to reliably detect a defective seal.

The capacitance detected by the pair of capacitance sensors 320 is extracted as a voltage, amplified by the amplifying means 321 as shown in FIG. 7, and then output to the voltage measuring means 340. It The capacitor 322 and the resistor 323 provided in the amplification means 321 are feedback means for reducing noise. The amplifying means 321 may be provided commonly to the pair of capacitance sensors 320 or may be provided independently.

The oscillation circuit 330 has a predetermined voltage (20 V).
Then, it is a circuit that generates an alternating current of a predetermined frequency (20 kHz) between the pair of capacitance sensors 320 and the ground. Then, the capacitance sensor 320 generates a capacitance according to the distance from the opposing conductive layer 102, and the generated capacitance is amplified by the amplifying unit 321 as described above, and then the voltage measuring unit 340. Is output.

The voltage measuring means 340 measures the voltage by adding the outputs of the pair of capacitance sensors 320. In this embodiment, the voltage amplified by the amplifying means 321 is measured. Then, the voltage measuring means 340 seals the packaging material 100 having the heat-welded portion 105 that has passed through the pair of capacitance sensors 320 when the measured voltage rises above a preset threshold voltage sV. Judgment means 3 for judging that it is defective
41, it outputs a seal defect signal to the discharging means 400 when it determines a seal defect.

It should be noted that the threshold voltage sV is determined by the heat-welded portion 10
It is set by adding the voltage value (for example, 2 V) generated by the above-mentioned thickness difference t3 to the average voltage xV of 5 (sV = xV +
2V). The threshold voltage sV can be set manually. The method of setting the threshold value sV is determined by the oscillograph 370 by the voltage measuring means 3
Read the average voltage xV of the output voltage measured at 40.
Then, the threshold value sV is set by adding the voltage value (for example, 2V) generated by the thickness difference t3 to the read average voltage xV.

As described above, by providing the threshold voltage so that it can be manually set, changes in temperature and humidity,
Alternatively, it is possible to easily set a threshold value for determining a sealing failure in accordance with the thickness change of the heat-welded portion 105 to be used. In addition, the oscillograph 370 has a voltage measuring means 34.
By displaying the output voltage measured at 0, the threshold s
The person who set V can easily read the average voltage xV of the heat-welded portion 105.

The end measurement cutting means 350 cuts the measurement of both ends of the heat-welded portion 105 by the pair of capacitance sensors 320, and as shown in FIG. Edge detection sensor 35 for detecting
1 (using an optical sensor), the end detection sensor 35
1 for a predetermined time immediately after detecting the heat-welded portion 105, and for a predetermined time from a straight line through which the heat-welded portion 105 passes through the pair of capacitance sensors 320, both ends of the heat-welded portion 105 by the pair of capacitance sensors 320 are detected. A sequence circuit 352 for cutting the measurement to stop the measurement is provided. The end detection sensor 351 and the sequence circuit 352 constitute a detection unit that detects both ends of the heat-welded portion 105 that passes through the pair of capacitance sensors 320.

In this way, the end measurement cutting means 350 detects both ends of the heat-welded portion 105 passing through the pair of capacitance sensors 320, and the both ends of the heat-welded portion 105 are connected to the pair of capacitance sensors 320. By providing so as not to measure in step 2, it is possible to eliminate the problem of erroneously detecting a curl generated at the end of the heat-welded portion 105 as a defective seal.

(Description of Ejecting Means 400) Ejecting Means 400
When the seal failure signal is received from the determination unit 341 of the measuring unit 300, the packaging material 10 that has generated the seal failure signal.
0, that is, the output voltage measured by the voltage measuring means 340 is
This is a device for discharging the packaging material 100 having the heat-welded portion 105 that has risen above a preset threshold voltage sV from the transportation path.

As described above, since the packaging material 100 having a defective seal portion is automatically removed from the conveying path by the discharging means 400, the work site for detecting a defective seal can be unmanned. And, it is very effective by unmanning the work site for detecting the defective seal.

[Operation of Embodiment] Next, the operation of the main part of the seal defect detecting device of this embodiment will be described. Start the seal defect detection device. Then, as shown in (a) of FIG. 9, when the heat-welded portion 105 having no defective seal portion passes through the pair of capacitance sensors 320, the oscillograph 370 shows that shown in (b) of FIG. 9. Such a waveform is generated. When the threshold voltage sV is set, the average voltage xV of the heat-welded portion 105 is read from the waveform as shown in FIG. 9B, and a voltage obtained by adding 2V to the read average voltage is added to the threshold voltage sV.
Set as. That is, the average voltage xV is, for example, 13V.
Then the threshold voltage sV becomes 15V.

When the heat-welded portion 105 having no defective seal portion passes through the pair of capacitance sensors 320, the measuring portion 300
The maximum voltage measured by is, as shown in FIG.
Do not exceed 5V. Therefore, the determination unit 341 does not output the seal failure signal to the ejection unit 400.

Here, as shown in FIG. 10 (a), a pair of electrostatic capacity sensors having a pair of heat-welded portions 105 having a defective sealing portion A in which a paper having a width of 0.5 mm is caught in the heat-welded portion 105. Three
When passing through 20, as shown in (b) of FIG. 10, the voltage measured by the measuring unit 300 exceeds 15V in the defective seal portion A in which the paper is caught. Therefore, the determination means 341
Outputs a defective seal signal to the discharging means 400, and the discharging means 400 discharges the packaging material 100 in which the paper is caught from the transport path.

Further, as shown in FIG. 11A, when the heat-welded portion 105 having the defective sealing portion B in which the heat-welded portion 105 has entrapped air passes through the pair of capacitance sensors 320. As shown in (b) of FIG. 11, the voltage measured by the measuring unit 300 is 15 at the defective seal portion B in which air is trapped.
Cross V Therefore, the determination unit 341 is the discharge unit 4
A sealing failure signal is output to 00, and the discharging unit 400 discharges the packaging material 100 in which air is trapped from the transport path.

[Effects of the Embodiment] The packaging material 100 of this embodiment.
In the device for detecting defective seal, the pair of capacitance sensors 32
The interval of 0 is set to 0.35 mm, the sensor diameter of the pair of capacitance sensors 320 is set to 1.0 mm, and the response frequency obtained from the frequency of the AC voltage applied to the pair of capacitance sensors 320 is set to 1 kHz or more. By setting, it is possible to detect the sealing failure of 200 packaging materials 100 per minute.

If the distance between the pair of capacitance sensors 320 is set to be narrower than 0.3 mm, which is obtained by adding 0.1 mm to the thickness of 0.2 mm of the heat-welded portion 105, the heat-welded portion 105 is formed.
It becomes difficult to reliably guide the heat-welded portion 105 between the pair of capacitance sensors 320 due to the bending of the
As a result, it becomes impossible to detect the sealing failure of 200 packaging materials 100 per minute.

If the distance between the pair of capacitance sensors 320 is set to be wider than 0.4 mm, which is obtained by adding 0.2 mm to the thickness of 0.2 mm of the heat-welded portion 105, the heat-welded portion 105 is formed.
The distance between the pair of electrostatic capacity sensors 320 becomes longer, the detection accuracy of the electrostatic capacity sensor 320 decreases, and the detection accuracy of the defective seal decreases.

On the other hand, when the sensor diameter of the pair of capacitance sensors 320 is set to be smaller than 0.5 mm, the sensor area is small. The gap between the pair of capacitance sensors 320 is set to a thickness of the heat-welded portion 105 of 0.2 mm,
It becomes necessary to provide the width narrower than 0.3 mm, which is the addition of 0.1 mm, and as a result, as described above, it becomes difficult to reliably guide the heat-welded portion 105 between the pair of capacitance sensors 320. .

When the sensor diameter of the pair of capacitance sensors 320 is set to be larger than 2.0 mm, the sensor area is large, so that the possibility of straddling the defective seal portion is increased. When the sensor diameter crosses over the defective seal portion, the voltage measuring means 3
In some cases, the voltage measured by 40 does not reach the threshold,
As a result, the accuracy of detecting a defective seal becomes low.

Specifically, a pair of capacitance sensors 320
If the sensor diameter is larger than 2.0 mm,
As shown in 0 (a), the heat-welded portion 105 having the seal-defective portion A in which the paper of 0.5 mm width is bitten into the heat-welded portion 105 is 1
When passing through the pair of capacitance sensors 320, as shown in FIG. 12, the sensor diameter straddles the defective seal portion, and as a result, the voltage at the portion where the paper is caught is 2V added to the average voltage. The threshold will not be reached.

Furthermore, the response frequency obtained from the frequency of the AC voltage applied to the pair of capacitance sensors 320 is 1 k.
If set lower than Hz, the pair of capacitance sensors 32
The decomposition ability of 0 decreases, and it becomes impossible to detect the sealing failure of 200 packaging materials 100 per minute.
In this embodiment, the response frequency obtained from the frequency of the AC voltage is set to 5 kHz, which is higher than 1 kHz.
Per minute, defective sealing of 200 packaging materials 100 can be detected with high accuracy.

[Modification] In the above embodiment, an example in which a seal defect is detected by a pair of capacitances is shown in FIG.
As shown in FIG. 3, in order to detect a seal defect in a direction orthogonal to the moving direction of the heat-welded portion 105, a plurality of pairs of capacitance sensors 320 are used, and the pair of capacitance sensors 320 do not interfere with each other. May be provided as follows. In this way, by detecting the seal defect in the direction orthogonal to the moving direction of the heat-welded portion 105, the detection accuracy of the seal defect is improved and the commercial value can be increased.

Further, in the above-mentioned embodiment, an example in which the sealing failure of the packaging material 100 containing the retort food is detected has been described. However, the sealing failure of the packaging material 100 containing other contents such as confectionery is detected. May be provided as follows.

[Brief description of drawings]

FIG. 1 is a schematic side view of a seal defect detection device for a packaging material (embodiment).

FIG. 2 is a schematic view of a packaging material (Example).

FIG. 3 is a cross-sectional view of a packaging material (Example).

FIG. 4 is a schematic top view of a moving unit (embodiment).

FIG. 5 is a schematic cross-sectional view of a moving unit showing a lateral guide (Example).

FIG. 6 is a schematic view of a measurement unit (Example).

FIG. 7 is a schematic view of an amplifying means for obtaining a measurement output (Example).

FIG. 8 is a schematic explanatory view of an edge measurement cutting means (Example).

FIG. 9 is a schematic view of a packaging material having no defective seal and a graph showing a waveform of output voltage (sensor diameter 1.0 mm, example).

FIG. 10 is a schematic view of a packaging material in which 0.5 mm-width paper is bitten and a graph showing a waveform of output voltage (sensor diameter 1.
0 mm, example).

FIG. 11 is a schematic view of a packaging material in which air is trapped and a graph showing a waveform of output voltage (sensor diameter 1.0 mm, example).

FIG. 12 is 0.5 when the sensor diameter is 2.0 mm or more.
It is a graph which shows the waveform of the output voltage when a paper of mm width is bitten (Example).

FIG. 13 is an explanatory diagram showing an arrangement state of a pair of capacitance sensors (modification).

[Explanation of symbols]

 100 packaging material 102 conductive layer 103 heat-welding layer 104 sheet member 105 heat-welding portion 200 moving means 202 endless belt 203 partition 210 unwanted material removing means 220 lateral guide 310 facing member 320 capacitance sensor 330 oscillating circuit 340 voltage measuring means 341 judgment Means 350 Edge measurement cutting means 370 Oscillograph 400 Ejection means

Claims (13)

[Claims] 1. A ready-made bag having a conductive layer and a heat-welding layer,
A moving means for moving the packaging material whose opening is heat-welded after containing the inclusions therein, and a position provided on the way of passage of the packaging material moved by this moving means, and sandwiching the heat-welded portion. A pair of capacitance sensors that are arranged to face each other with a predetermined gap therebetween, an oscillation circuit that gives an AC voltage of a predetermined frequency at a predetermined voltage to the pair of capacitance sensors, and an output of the pair of capacitance sensors. A voltage measuring means for adding and measuring a voltage, and when the output voltage measured by the voltage measuring means rises above a preset threshold voltage, the voltage passed through the pair of capacitance sensors. In the seal defect detecting device for detecting the seal defect of the heat-welded portion, the predetermined gap is 0.1 to 0.
It is provided at an interval of 2 mm, and each sensor diameter of the pair of capacitance sensors is 0.5 to
A seal defect detecting device provided in a range of 2.0 mm. 2. The seal defect detecting device according to claim 1, wherein a response frequency obtained from the predetermined frequency is set to 1 kHz or higher. 3. A ready-made bag provided with a conductive layer and a heat-welding layer,
A moving means for moving the packaging material whose opening is heat-welded after containing the inclusions therein, and a position provided on the way of passage of the packaging material moved by this moving means, and sandwiching the heat-welded portion. A pair of capacitance sensors that are arranged opposite to each other with a predetermined gap therebetween, an oscillation circuit that applies an AC voltage of a predetermined frequency and a predetermined frequency to the pair of capacitance sensors, and an output of the pair of capacitance sensors. A voltage measuring means for adding and measuring a voltage, and when the output voltage measured by the voltage measuring means rises above a preset threshold voltage, the voltage passed through the pair of capacitance sensors. A seal defect detecting device for detecting a seal defect at a heat-welded portion. 4. The seal defect detecting device according to claim 1, wherein the pair of capacitance sensors is provided in the middle of passage of the packaging material moved by the moving means, A seal defect detecting device characterized by being fixed to opposing members having a U-shaped cross section, which are opposed to each other at a position sandwiching a heat-welded portion with a predetermined gap. 5. The seal defect detecting device according to claim 1, wherein the moving means includes an endless belt that sequentially moves the plurality of packaging materials, and a surface of the endless belt is provided. A seal defect detecting device comprising: a partition for partitioning the packaging material; and lateral guides on both sides of the endless belt that substantially match the width of the packaging material. 6. The seal defect detecting device according to claim 5, wherein the lateral guide on the side for guiding the heat-welded portion toward at least the pair of capacitance sensors is provided between the pair of capacitance sensors. A seal failure detecting device provided in a U-shaped cross section for restricting the curvature of the heat-welded portion to be cut within a predetermined range. 7. The device for detecting a seal defect according to claim 1, wherein the threshold voltage is generated by a difference between a thickness of the heat-welded portion before welding and a thickness after the welding. A seal defect detecting device characterized by being set to a voltage value. 8. The seal defect detecting device according to claim 1, wherein the added output voltage of the pair of capacitance sensors measured by the voltage measuring means is determined by an oscillograph. A seal defect detecting device characterized by being visually displayed. 9. The seal defect detecting device according to claim 1, wherein the threshold voltage is set so that it can be set manually. 10. The seal defect detection device according to claim 1, further comprising a detection unit that detects both ends of the heat-welded portion that passes through the pair of capacitance sensors. The seal defect detecting device, wherein the measuring means is provided so as not to measure an output voltage when both ends of the heat-welded portion pass through the pair of capacitance sensors. 11. The seal defect detecting device according to claim 1, wherein high pressure air is blown from both sides of the heat-welded portion guided by the pair of capacitance sensors. A defective seal detection device. 12. The seal defect detecting device according to claim 1, wherein the moving unit has an output voltage measured by the voltage measuring unit higher than a preset threshold voltage. In this case, the seal defect detecting device is provided with a discharging unit that discharges the packaging material having the heat-welded portion that has passed through the pair of capacitance sensors from a transportation path. 13. The seal defect detecting device according to claim 1, wherein the pair of electrostatic capacitances are arranged to detect a seal defect in a direction orthogonal to a moving direction of the heat-welded portion. A seal defect detecting device, wherein the sensors are provided at a plurality of positions so as not to interfere with each other.