JPH06345062A - Sealing defect detection method for retort pouch packing material and apparatus - Google Patents

Abstract

PURPOSE:To provide the detective method and its apparatus by which sealing defects of the heat-sealing part of a retort pouch-packing material can be effectively detected. CONSTITUTION:An electric conductive layer forces the heat-sealed part of a retort pouch-packing material electrically connected with an earthing electrode to pass into the groove of a sensor 11 and the distances L1, L2 between respective probes 13, 14 and the electric conductive layer are measured basing on the electrostatic capacity between the respective probes 13, 14 and the electric conductive layer. Gross thickness (t) between respective electric conductive layers including polypropylene forming the heat-sealed part in the retort pouch- packing material is calculated from these distances L1, L2 and the width (p) between respective probes 13, 14. And the sealing defects are detected basing on the calculated gross thickness (t). Since the gross thickness (t) becomes large at the point of sealing defect, it can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retort pouch packaging material, a method for detecting a seal defect in a heat-welded portion heat-welded after filling the contents, and an apparatus therefor.

[0002]

2. Description of the Related Art In a retort pouch in which fluid food or the like is hermetically packaged, a retort pouch packaging material in which three sides are hermetically sealed (sealed) is filled with a required filling material, and then a filling port is heat-welded. It is hermetically sealed.
In this sealing step, a sealing failure may occur due to the fouling of the heat-welding surface (sealing surface) due to the splash of the filling material at the time of filling and the adhesion of water droplets due to the vapor of the filling material.
Since such a sealing failure causes the filling contents to deteriorate or the surroundings to be soiled, it is necessary to reliably determine the presence or absence of a sealing failure after the filling process. Conventionally, this type of discrimination is performed by visual inspection by an operator.

[0003]

As described above, in the related art, the detection of the presence or absence of a seal defect in the retort pouch relies on visual inspection by a person, which leads to a reduction in the efficiency of the production process. There are problems such as increased production costs due to personnel costs, and improvements in these points are desired.

The present invention provides a method and apparatus for detecting a seal defect that efficiently detects the presence or absence of a seal defect in a heat-welded portion in a retort pouch after filling, and further contributes to automation of an inspection process therefor. The purpose is to The sheet member of the packaging material shown in the present invention is in the form of a film or sheet, and has a thickness of about 0.4 mm or less.

[0005]

According to the present invention, a plurality of types of sheet members each including at least a conductive layer are laminated, and a heat-welding sheet member is disposed inside the conductive layer on the facing surface. In a retort pouch packaging material, wherein the heat-welding sheet member of the facing surface is heat-welded, a method for detecting a seal defect in a heat-welded portion of the retort pouch packaging material, which passes through the heat-welded portion of the retort pouch packaging material. Two detection electrodes provided on both sides of the groove and facing each other, and a ground electrode for the two detection electrodes that are conductively connected to the conductive layer of the retort pouch packaging material. The conductive layer position detecting means is provided, and the two detecting electrodes of the conductive layer position detecting means, the two detecting electrodes detected by the ground electrode, and the retort pouch packaging material are provided. Each distance between the conductive layer and each of the detection electrodes is measured from each capacitance between each of the conductive layers, and the conductivity is calculated from these distances and the distance between the two detection electrodes. The thickness between layers is calculated, and a seal defect of the retort pouch packaging material is detected based on the calculated thickness.

As an apparatus therefor, a retort pouch in which a plurality of types of sheet members each including at least a conductive layer are laminated, and the heat-welding sheet members are arranged inside the conductive layers on the opposite surfaces, respectively. Packaging material,
In the sealing failure detection device of the heat-welded portion of the retort pouch packaging material in which the heat-welding sheet member of the facing surface is heat-welded, having a groove for passing the heat-welded portion of the retort pouch packaging material, The two detection electrodes are provided with two detection electrodes provided facing each other on both sides of the groove and a ground electrode which is conductively connected to the conductive layer of the retort pouch packaging material and is connected to the two detection electrodes. And each distance between the conductive layer and each of the detection electrodes from each capacitance between the two detection electrodes detected by the ground electrode and each of the conductive layers of the retort pouch packaging material. Conductive layer position detecting means for measuring respectively, and thickness calculating means for calculating the thickness between the conductive layers from the distance detected by the conductive layer position detecting means and the distance between the two detection electrodes. Comprising a seal failure detection means for detecting a sealing failure of the retort pouch packaging material based on the thickness of the conductive layers that is calculated by said thickness seen calculation means.

[0007]

In the present invention, when the retort pouch packaging material is passed through the groove of the conductive layer position detecting means, the heat-welded portion of the retort pouch is placed between the two detection electrodes facing each other of the conductive layer position detecting means. As a result, capacitance appears between the two conductive members included in the retort pouch packaging material and the respective detection electrodes. Here, if the area of the detection electrode is significantly smaller than the area of the conductive layer of the sheet member of the retort pouch packaging material, if the area of the conductive layer corresponding to the area of the detection electrode is static, Since the capacitance can be measured, the detected capacitance is inversely proportional to the distance between the conductive layer and the detection electrode.

On the other hand, in the heat-welding portion of the retort pouch packaging material that is heat-welded, when heat is applied by being sandwiched from the outside of the packaging material by a jig such as a heat bar, heat is applied to the opposing inner side of the packaging material. Since only the sheet members for welding are melted and adhered to each other, the total thickness of the two sheet members for thermal welding after the thermal welding is larger than the total thickness before the thermal welding in the portion where the thermal welding is normally performed. If the heat-welding is abnormal, the thickness increases, which means that the distance between the conductive layers on the outside of the heat-welding sheet is the heat-welding of the heat-welding sheet member. Is small in the normal part and large in the abnormal part of heat welding.

That is, if the heat-sealing of the heat-welding sheet inside each conductive layer is normal, each conductive layer has a distance from each detection electrode of the conductive layer position detecting means to each conductive layer. When the heat welding is abnormal, the total distance from the detection electrodes of the conductive layer position detecting means to the conductive layers is decreased. As a result, the distance between each detection electrode of the conductive layer position detection means and each conductive layer can be obtained from the capacitance between each detection electrode of the conductive layer position detection means and each conductive layer.

Further, since the distance between the detection electrodes in the conductive layer position detecting means is fixed, the distances between the detection electrodes to the conductive layers of the retort pouch packaging material with respect to the detection electrodes can be determined. By subtracting, the thickness between the conductive layers including the heat-welded portion located inside the conductive layer can be calculated. This thickness is small if the heat-sealing is normally performed and becomes large if the heat-welding is abnormal, so that a seal defect of the heat-welded portion can be detected based on this.

As a method of electrically connecting the conductive layer of the retort pouch packaging material to the ground electrode, the bottom portion of the groove is used as the ground electrode, and the exposed portion of the conductive layer at the end of the retort pouch packaging material is grooved. What to conduct by contacting the bottom part of the, or the gripping part of the support device that supports or grips the retort pouch packaging material, by providing a metal needle for conduction, when gripping the retort pouch packaging material, It is conceivable to insert a metal needle into the packaging material to make it conductive.

[0012]

According to the present invention, the conductive layer of the retort pouch packaging material is conductively connected to the ground electrode, and thermal welding between the conductive layers is performed based on the capacitance between the detection electrode and the conductive layer on both sides of the groove. Since the thickness of the portion is calculated and the seal defect is detected from the thickness, it is possible to easily detect the seal defect with respect to the entire width of the heat welded portion with respect to the heat welded portion having a certain width. In addition, rather than detecting the irregularities on the outside of the heat-welded part of the retort pouch packaging material, the thickness of the heat-welding sheet member is directly measured to detect a seal defect, so that foreign matter is caught on the heat-welded surface. It is possible to detect not only when there is a jam, but also when there is a sealing failure or peeling due to heating failure during heat welding. Further, since the thickness of the heat-welded portion itself is measured, the surface of the retort pouch packaging material is not affected by wrinkles, peeling, unevenness, or the like and the surface color.

[0013]

EXAMPLES Next, the present invention will be explained based on examples. FIG. 1 shows an example of the appearance of a retort pouch packaging material 100 in which it is determined whether or not there is a sealing failure. In this retort pouch packaging material 100, three layers of sheet members are laminated,
As shown in FIG. 1 (a), after filling the contents in a prefabricated bag-like one that is airtightly bonded with only one left in advance, the other one is subjected to heat treatment with a heat bar or the like. As shown in FIG. 1 (b), the heat-welding portion 100a is heat-welded, and a defective seal is discriminated.

As shown in FIG. 2 (a), the structure of the retort pouch packaging material 100 is obtained by coating both sides of an aluminum foil as a conductive layer 101 with PET 102 and a polypropylene layer 103 as a heat-welding sheet member, respectively. When the sheet members of the layers are laminated and the surface of the polypropylene layer 103 is overlaid on the inside and heat welding is performed, the total thickness t of the polypropylene layer 103, which is the thickness t1 in FIG. As shown in (b), the total thickness t of the polypropylene layer 103 becomes smaller than the thickness t2.
Becomes

FIG. 3 shows an outline of a seal defect detecting device 1 according to an embodiment of the present invention. The seal defect detection device 1 includes a capacitance displacement meter 10 and an arithmetic processing unit 20 that detects a seal defect based on the measurement signal. As shown in FIG. 4, a groove 12 for allowing the heat-welded portion 100a of the retort pouch packaging material 100 to pass through is formed in the sensor portion 11 of the capacitance displacement meter 10, and the groove 12 of the sensor portion 11 is formed.
Probes 13 and 14 for measuring capacitance with respect to the retort pouch packaging material 100 are provided on both sides of the wall.
However, the detection portion thereof is arranged facing the groove 12 in a hole formed so as to penetrate each of the wall portions on both sides of the groove 12. Further, a conductive contact member 15 is provided on the bottom of the groove 12 as a ground electrode for conductively connecting to the conductive layer 101 of the retort pouch packaging material 100.

The probes 13 and 14 are the sensor unit 1
When the retort pouch packaging material 100 is arranged in the groove 12 of No. 1, a capacitor having air in the groove 12 and PET 102 of the retort pouch packaging material 100 as a dielectric is formed with respect to the conductive layer 101 of the retort pouch packaging material 100. , Having a detection electrode for detecting its capacitance,
The probes 13 and 14 are connected to capacitance-voltage conversion circuits 16 and 17 that generate a voltage according to the capacitance of the formed capacitors.

As shown in FIG. 5, the capacitance-voltage conversion circuits 16 and 17 are well-known ones which are composed of an oscillator OSC for generating a sine wave having a frequency of about 20 kHz and an amplifier circuit by an operational amplifier OP, and the output of the operational amplifier OP. The voltage e is represented by the capacitance Ci between the probes 13 and 14 and the conductive layer 101 of the retort pouch packaging material 100 and the feedback capacitor Cf as e = − (Ci / Cf) · ei Formula 1 , Which is approximately proportional to the capacitance Ci, and therefore e = K · ΔC Formula 2 and an output voltage proportional to the change ΔC of the capacitance Ci is obtained. Here, K represents the sensitivity of the equivalent circuit. In Equation 2, when ΔC is regarded as an increase in the capacitance when facing the retort pouch packaging material 100 with respect to the capacitance when the electrodes of the probes 13 and 14 are separated from the retort pouch packaging material 100, e = K · (ε0 · εs · S / L) Equation 3 is obtained, and the output voltage corresponding to the distance L (displacement) is obtained. Here, ε0 is the dielectric constant of vacuum, εs is the relative dielectric constant of the dielectric, and S is the facing area of the detection electrode of the probe. Based on the value of the output voltage e, the distances L1 and L between the probes 13 and 14 and the conductive layer 101 in the retort pouch packaging material 100.
2 can be calculated. In the above capacitance-voltage conversion circuits 16 and 17, the signal of the oscillator OSC is given through an amplifier for operational amplifier not shown, and the output voltage e of the operational amplifier OP is not shown for linearizer circuit and operational amplifier for amplification. Is transmitted to the arithmetic processing unit 20 via.

The arithmetic processing unit 20 provided at the subsequent stage of the capacitance displacement meter 10 includes capacitance-voltage conversion circuits 16 and 17.
From each output voltage of, the total thickness t including the polypropylene 103 between the conductive layers 101 in the heat-sealed retort pouch packaging material 100 is calculated, and the heat-welded portion is calculated from the calculated total thickness t. The seal defect determination unit 100a determines whether there is a seal defect of 100a.

The thickness calculating section 21 calculates the total thickness t from each output voltage corresponding to the above distances L1 and L2 by t = p- (L1 + L2). Ask by. However, p is the probe 1 in the sensor unit 11.
It is a fixed value indicating the width between the detection units 3 and 14, and
The width is set to be substantially the same as the width of 2 (for example, 1 mm).

The seal failure determination section is an AD conversion module 2 for converting the output signal of the thickness calculation section 21 into a digital signal.
2 and a personal computer (personal computer) 23 for determining a seal defect based on a digital signal from the AD conversion module 22. The personal computer 23 determines the output signal of the AD conversion module 22 based on a preset threshold value, and when the output signal is greater than the threshold value, determines that the total thickness t of the polypropylene 101 is large and that the seal is defective. A seal failure notification buzzer,
Seal failure notification lamp, target retort pouch packaging material 1
00 is removed from the inspection line or the like, and output processing is performed to indicate that the seal is defective.

In the detection of the seal defect of the retort pouch packaging material 100 by the seal defect detection device 1 of the present embodiment having the above-mentioned configuration, the end of the heat-welded portion 100a of the retort pouch packaging material 100 after the heat-welding process is detected by the sensor. Since the conductive layer 101 in the retort pouch packaging material 100 comes into contact with the conduction contact member 15 when the heat-welded portion 100a is passed at a predetermined speed while being brought into contact with the conduction contact member 15 of the groove 12 of the portion 11. , The conductive layers 101 on both sides serve as ground electrodes for the probes 13 and 14 in the capacitance displacement meter 10, and the capacitance-voltage conversion circuits 16 and 17 are provided.
The conductive layers 101 and the probes 13 and 1 on the outside thereof.
An output voltage corresponding to the distances L1 and L2 between the conductive layers 101 and 4 appears, and the thickness calculator 21 calculates the total thickness t between the conductive layers 101 based on these output voltages.

When the heat-welded portion 100a is normally heat-welded as shown in FIG. 6 (a), the thickness calculation portion 2
As for the output voltage of No. 1, as shown by the solid line a in FIG. 7, the heat-welded portion 100 a of the retort pouch packaging material 100 has the probe 1
A signal of a constant voltage appears only while passing between No. 3 and No. 14, but as shown in FIGS. 6B and 6C, if there are abnormal portions 100b and 100c of thermal welding, those portions will disappear. When passing between the probes 13 and 14, a signal indicating that the total thickness t is large appears as indicated by the broken line b and the alternate long and short dash line c in FIG. The signal indicating the total thickness t is discriminated based on a predetermined threshold value set in the personal computer 23, and the output signal indicating the total thickness t of the thickness calculator 21 exceeds the threshold value or the set change value. In this case, it can be determined that the seal defect has been detected.

It should be noted that the operation of determining the seal failure in the personal computer 23 can be performed by moving the heat-welded portion 100a of the retort pouch packaging material 100 with respect to the fixed sensor portion 11 using a moving tool.
At that time, the retort pouch packaging material 100 is attached to the sensor unit 11
It is possible to automate the seal failure determination by synchronizing the operation of the moving instrument passing through the groove 12 and the determination operation of the personal computer 23 with a predetermined time difference.
FIG. 8 shows a modification of this embodiment. The retort pouch packaging material 100 and the sensor unit 11 are used to determine whether the seal is defective.
Since it is sufficient for and to move relative to each other, for example, as shown in FIG. 8, the retort pouch packaging material 100 is fixed,
The sensor unit 11 of the capacitance type displacement meter 10 may be moved with respect to the retort pouch packaging material 100 by a driving device using a motor or the like.

FIG. 9 shows a second embodiment of the present invention. In the above embodiment, the conductive layer 10 of the retort pouch packaging material 100 is used.
1 and a ground electrode of the capacitance displacement meter 10 are electrically connected by a contact member 15 for conduction provided at the bottom of the groove 12 of the sensor unit 11.
However, instead of the contact member 15 for conduction, FIG.
As shown in, the holding member 30 for holding the retort pouch packaging material 100 is provided with a conducting needle 31, and when the retort pouch packaging material 100 is grasped, the needle 31 is
You may make it contact the conductive layer 101 through the ET 102. Thereby, when the retort pouch packaging material 100 is passed through the groove 12 of the sensor unit 11, a more stable conductive connection can be performed. In this case, the plurality of gripping members 30
Each of them is provided with a conduction needle 31 or a single holding member 3
By providing a plurality of conducting needles 31 such as providing a plurality of conducting needles 31 at 0, the conducting connection between the conductive layer 101 and the capacitance displacement meter 10 can be further stabilized.

In the above embodiment, the capacitance type displacement meter 10
In the case where the sensor part 11 and the retort pouch packaging material 100 are relatively moved, one sensor part 11 is moved relative to the entire heat-welded part 100a of the retort pouch packaging material 100. However, as shown in FIG. 10, the sensor unit 11 includes a plurality of probes 13 to 13c, 14
14c may be provided and these may be moved relative to one retort pouch packaging material 100.
In this case, the relative movement distance can be shortened,
It is possible to shorten the processing time for determining the seal defect and improve the processing capacity.

FIG. 11 shows a capacitance-voltage conversion circuit 16,
17 shows another embodiment. In each of the above embodiments, an operational amplifier is used, but in this embodiment, a known circuit configuration in which an AC oscillator, a diode and a capacitor are combined is used. In the figure, C1 is the capacitance formed between the detection electrode of the probe 13 and the retort pouch packaging material 100, and the distance between the detection electrode of the probe 13 and the conductive layer 101 of the retort pouch packaging material 100. ΔC is generated for L. C2 is a capacitance for balancing the circuit with respect to C1, and the diodes D1 to D
4 are equal, C1 = C2, C3 = C4 and ΔC =
When it is 0, the output voltage e is set to 0 [V] in a steady state. As a result, the resistance value of the diode is small and can be neglected. Therefore, if C1 = C2 and C3 = C4, the output voltage e is smoothed through the filter. Therefore, e = K · ΔC is approximately expressed by Equation 11, and C1 Output voltage e proportional to the change (capacitance ΔC) of the probe 1 is obtained.
Distances L1 and L2 between 3, 14 and the conductive layer 101 in the retort pouch packaging material 100 can be calculated.

As described above, according to the present invention, in the retort pouch packaging material, the thickness of the portion where the heat welding is defective is measured by the capacitance displacement meter, and the seal failure of the heat welding is determined based on the measurement result. Since it is detected, it is possible to accurately detect the defective seal. Further, since the thickness of the heat-welded portion is detected by using the electrostatic capacitance, it is possible to accurately determine whether or not there is a seal defect in the heat-welded portion having a certain width. In addition, since the thickness of the heat-welded portion itself is measured, the surface of the retort pouch packaging material is not affected by the unevenness of the surface of the retort-pouch packaging material, the wrinkles of PET on the outside of the aluminum foil by the conductive layer, and the peeling.

[Brief description of drawings]

FIG. 1 is an external view of a retort pouch packaging material to which the present invention is applied.

FIG. 2 is a partial cross-sectional view showing the structure of a retort pouch packaging material to which the present invention is applied.

FIG. 3 is a block diagram showing a configuration of a seal defect detecting device showing the present invention.

FIG. 4 is an external view showing an example of a sensor unit of the seal defect detecting device in the embodiment of the present invention.

FIG. 5 is a circuit diagram showing a capacitance-voltage conversion circuit in the seal defect detecting device of the embodiment of the present invention.

FIG. 6 is a diagram for explaining a seal defect in the retort pouch packaging material to which the seal defect detection operation according to the embodiment of the present invention is applied.

7 is a voltage waveform diagram showing an output voltage of a thickness calculating unit when a seal defect is detected in the retort pouch packaging material of FIG. 6 in the seal defect detecting device according to the embodiment of the present invention.

FIG. 8 is an external view showing a modified example of an apparatus for detecting a defective seal in the embodiment of the present invention.

FIG. 9 is an external view showing another example of the sensor unit of the seal defect detecting device in the embodiment of the present invention.

FIG. 10 is a plan view showing still another example of the sensor portion of the seal defect detecting device in the embodiment of the present invention.

FIG. 11 is a circuit diagram showing another embodiment of the capacitance-voltage conversion circuit in the seal defect detecting device of the embodiment of the present invention.

[Explanation of symbols]

1 Sealing Defect Detection Device (Sealing Defect Detection Device for Retort Pouch Packaging Material) 11 Sensor Part 12 Grooves 13 and 14 Probe (Two Detection Electrodes) 15 Conductive Contact Member (Ground Electrode) 16 and 17 Capacitance-Voltage Conversion Circuit (conductive layer position detection means) 21 Thickness calculation part (thickness calculation means) 23 Personal computer (seal defect detection means) 100 Retort pouch packaging material 100a Heat-welded portion 101 Conductive layer (conductive layer) 103 Polypropylene (heat-welding sheet) Element)

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Jiro Funato 2-119, Kameshu-cho, Handa-shi, Aichi Rainbow No. 4 Handa 401 (72) Inventor Chisato Ito 2-105, Toyonari, Taketoyo-cho, Chita-gun, Aichi

Claims (2)

[Claims] 1. A retort pouch packaging material in which a plurality of types of sheet members each including at least a conductive layer are laminated, and a heat-welding sheet member is disposed inside the conductive layer on the opposing surface, respectively. In the sealing failure detection method of the heat-welded portion of the retort pouch packaging material in which the heat-welding sheet member of the facing surface is heat-welded, having a groove for passing the heat-welded portion of the retort pouch packaging material, A conductive layer position detecting means having two detection electrodes provided on both sides of the groove and a ground electrode for conductively connecting to the conductive layer of the retort pouch packaging material is provided. A static layer is provided between the two detection electrodes of the conductive layer position detection means and the two detection electrodes detected by the ground electrode and the conductive layers of the retort pouch packaging material. Each distance between the conductive layer and each of the detection electrodes is measured from the capacitance, the thickness between the conductive layers is calculated from the distance and the distance between the two detection electrodes, and the calculated thickness is calculated. A method for detecting a seal defect of the retort pouch packaging material based on the above. 2. A retort pouch packaging material, wherein a plurality of types of sheet members each including at least a conductive layer are laminated, and a heat-welding sheet member is arranged inside the conductive layer on the opposing surface, respectively. In a sealing failure detection device of the heat-welded portion of the retort pouch packaging material in which the heat-welding sheet member of the facing surface is heat-welded, having a groove for passing the heat-welded portion of the retort pouch packaging material, The two detection electrodes are provided with two detection electrodes provided facing each other on both sides of the groove and a ground electrode that is conductively connected to the conductive layer of the retort pouch packaging material and is connected to the two detection electrodes. And each distance between the conductive layer and each detection electrode from each capacitance between the two detection electrodes detected by the ground electrode and each conductive layer of the retort pouch packaging material. Conductive layer position detecting means for measuring each, and thickness calculating means for calculating the thickness between the conductive layers from the distance detected by the conductive layer position detecting means and the distance between the two detection electrodes. And a seal defect detecting unit for detecting a seal defect of the retort pouch packaging material based on the thickness between the conductive layers calculated by the thickness calculating unit, and a seal defect detection of the retort pouch packaging material. apparatus.