JP2000241285A - Method for inspecting heat seal part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a defective seal automatically by measuring the temperature distribution of a part just heat sealed, inputting the measurement to a CPU and comparing with a preset value, and delivering an alarm signal if it is lower than the preset value. SOLUTION: Immediately after completing heat seal of a bag container, a heat seal completion signal is delivered from a signal input circuit 3 to a CPU 2 and a scanning radiation thermometer 1 measures temperature distribution of the seal part and delivers a temperature signal to the CPU 2. The CPU 2 compares the temperature signal with a predetermined set value and decides that the seal part is abnormal if the temperature signal is lower than the predetermined set value and delivers an alarm signal from an alarm output circuit 4. The set value is preferably determined by determining the means value of all temperature measurements and multiplying it by some coefficient or by determining the derivative of temperature distribution. According to the method, abnormality at the seal part can be detected quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quickly detecting an abnormality in a seal portion and automatically detecting a defective seal when heat-sealing a bag-like container to seal the same.

[0002]

2. Description of the Related Art In order to prevent the quality of goods stored in a bag-like container from being deteriorated, sealing of the container to shut out the air from the outside is performed in many fields of goods. For example, in the food field, so-called retort foods have been developed for a variety of foods, in which food such as curry and stew is put in a bag-shaped container formed by combining a plurality of resin films or metal films such as aluminum in a multilayered form, and sterilized and sealed. I have. These sealed containers are usually hermetically sealed by tightly joining the bag-like containers by heat sealing.

[0003] In these retort foods, it is important to completely sterilize and completely seal off the air from the outside air. If the seal is incomplete, even if the sterilization is completely performed, the food in the container will not be completely sterilized. It gradually deteriorates and rots. Therefore, it is extremely important to strictly inspect the seal portion, accurately grasp the seal state, and quickly detect a defective seal.

[0004] Inspection of the heat seal portion has been conventionally performed by various methods. For example, a sealed bag-shaped container
Submerge in water, observe the presence or absence of air bubbles from the seal under reduced pressure, put it in a decompression chamber, return to normal pressure, observe the presence or absence of deformation, visually observe the seal, etc. Inspect seals. However, since these methods are all observations with the naked eye, objectivity,
Lack of quickness, etc., makes it difficult to make an accurate judgment.
There is also a method of detecting a change in water vapor pressure in a room or the generation of volatile components by placing a bag-shaped container in a decompression chamber, but there is a disadvantage that it takes time, and there is a problem that automation is difficult with these methods. .

[0005]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies on a method of quickly detecting an abnormality in a heat seal portion and automatically inspecting for a defective seal. Found that the temperature of a part where sealing was not sufficiently performed, for example, a part where sealing failure occurred due to a biting of a container or the like, was lower than that of a part that was properly sealed.

[0006] That is, the present invention has been completed based on the above-mentioned findings, and an object of the present invention is to provide a sealing portion for sealing a bag-like container such as a retort food. It is an object of the present invention to provide a method for inspecting a heat seal portion, which can quickly detect an abnormality and automatically detect a seal failure.

[0007]

In order to achieve the above object, a method for inspecting a heat seal portion according to the present invention comprises the steps of: measuring a temperature distribution of a seal portion immediately after heat sealing;
When the CPU detects a temperature signal equal to or less than the set value as compared with a predetermined set value, the CPU immediately outputs a seal failure warning signal. In addition,
As a set value previously input to the CPU, a method of obtaining a threshold value or a differential value of the temperature distribution and using these values as set values is adopted.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied a method for detecting a sealing defect in a heat seal portion, and as a result, as described above, the temperature of a seal portion immediately after heat seal is lower than the temperature of a normally sealed portion. It was experimentally confirmed that the temperature of the portion where the sealing failure occurred was lowered.

That is, when the temperature distribution of the seal portion immediately after the heat sealing was measured, and the temporal change of the temperature distribution was measured, the result of FIG. 2 was obtained. FIG. 2 is a plot of the coordinates (position) in the sealing direction on the horizontal axis and the temperature on the vertical axis, showing the time-dependent change in the temperature distribution of the seal portion. Note that a scanning thermometer capable of one-dimensional temperature measurement along the sealing direction was used for temperature measurement.

From FIG. 2, immediately after heat sealing,
It is recognized that the temperature of the poorly sealed portion A becomes lower than the temperature of the normally sealed portion B, and the temperature of the entirety decreases with time and becomes the same temperature, and the low temperature portion of the poorly sealed portion disappears. However, it can be seen that the low-temperature portion of the defective sealing portion can be confirmed within about one second after the heat sealing.

[0011] The present invention thus, immediately after heat sealing,
Desirably, the temperature distribution of the seal portion is measured within 0.5 seconds after sealing, and this temperature signal is input to the CPU to detect a low-temperature portion. For the detection of the low-temperature portion, a predetermined set value is input to the CPU, and when a temperature signal equal to or lower than the set value is detected in comparison with the input temperature signal, a defective seal is detected.

The set value can be set by a predetermined threshold value or differential value. For example, a threshold value is determined in advance by calculating the average value of the temperature distribution, and when a value smaller than the threshold value is detected in the input temperature signal, it is detected as a seal failure. Alternatively, a differential value of the temperature distribution may be obtained, and a defective seal may be detected when the differential value sharply decreases.

In this manner, the temperature of the heat seal portion can be measured one-dimensionally in the sealing direction. For example, the temperature distribution of the seal portion is measured by a scanning radiation thermometer, a line sensor, or the like, and input to the CPU. Compares the input temperature signal with the set value, and if a temperature signal below the set value is detected, immediately outputs a seal failure signal to an external alarm device to automatically check for seal failure Becomes

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for inspecting a heat seal portion according to the present invention will be described below with reference to the block diagram shown in FIG.

FIG. 1 shows an apparatus used in the method for inspecting a heat seal portion according to the present invention, wherein 1 is a scanning radiation thermometer for one-dimensionally measuring the temperature of the heat seal portion in the sealing direction.
2 is a CPU that compares the input temperature signal with a set value and immediately outputs a seal failure alarm signal when a temperature signal equal to or lower than the set value is detected. 3 denotes a temperature of the seal portion immediately after heat sealing is completed. A signal input circuit 4 for inputting a heat seal completion signal to the CPU in order to measure the distribution is an alarm output circuit 4 for receiving an alarm signal indicating a defective seal and immediately outputting an alarm signal.

Immediately after the heat sealing of the bag-shaped container is completed, a heat sealing completion signal is input from the signal input circuit 3 to the CPU 2, and immediately after the heat sealing completion signal is input, the temperature of the sealing portion is detected by the scanning radiation thermometer 1. Distribution measurement is started, and a temperature signal is captured. The obtained temperature signal is input to the CPU 2, and the CPU 2 compares the temperature signal with a predetermined set value.

When the CPU 2 compares the temperature signal with the set value and detects a temperature signal lower than the set value, the CPU 2 determines that there is an abnormality in the seal portion and detects a seal failure. As the set value, for example, a method of using an average value of all the measured temperatures and using a threshold value calculated by multiplying the average value by a coefficient, or a method of calculating a differential value of the temperature distribution and using the differential value Are preferred.

When a temperature signal equal to or lower than the set value is detected in this way, it is immediately determined that there is a defective seal portion, and an alarm signal is output from the alarm output circuit 4 to the outside. Therefore, it is possible to quickly detect a seal abnormality in the heat seal portion and quickly and automatically detect a defective seal.

[0019]

As described above, according to the method for inspecting a heat seal portion of the present invention, the temperature distribution of the seal portion immediately after the heat seal is measured in a one-dimensional direction of the seal direction, and the temperature signal is compared with a set value. By doing so, the presence or absence of an abnormality in the seal portion is determined, so that an abnormality in the seal portion can be quickly detected, and a defective seal can be automatically and accurately detected. Therefore, for example, when a bag-like container containing a retort food or the like is tightly joined and sealed by heat sealing, it is extremely useful as an inspection method for quickly detecting an abnormality in a seal portion.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an apparatus used for a method for inspecting a heat seal portion of the present invention.

FIG. 2 is a graph illustrating a temporal change of a temperature distribution of a seal portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanning radiation thermometer 2 CPU 3 Signal input circuit 4 Alarm output circuit

Claims (2)

[Claims] 1. A temperature distribution of a seal portion immediately after heat sealing is measured, and a temperature signal is input to a CPU. When the CPU detects a temperature signal equal to or less than a predetermined value compared with a predetermined value, the CPU immediately performs the measurement. A method for inspecting a heat seal portion, comprising outputting a warning signal of a seal failure. 2. The method according to claim 1, wherein the set value is determined by a threshold value or a differential value.