JP7202565B2 - Magnetic field strength measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for measuring the magnetic field strength of a container cap sealing device that utilizes heat accompanying the generation of an electromagnetic induction current (eddy current) in a container such as a lactic acid beverage.

A production line for a container to be filled with a lactic acid bacteria drink or the like includes a sealing process using a cap-sealing high-frequency induction heating device for sealing the container with an aluminum cap after the container is filled with the lactic acid bacteria drink or the like.
In this sealing step, first, an aluminum cap having a heat-melting adhesive applied to the surface to be bonded to the container in advance is put on the top opening of the container. Then, while a high-frequency magnetic field is applied from above by a metal cylindrical body, the container is pressed upward by a pressing means from below. At this time, an eddy current is generated in the aluminum cap by an electromagnetic induction action, and the temperature of the aluminum cap is raised by the heat generation action of the eddy current and the specific resistance of the aluminum cap, and the adhesive is melted for sealing. On the transport line, a configuration is adopted in which a plurality of combinations of metal cylindrical bodies and pressing means are provided so that a plurality of containers can be sealed.

In such a sealing device having a plurality of metal cylinders and pressing means, there may be a difference in strength of the magnetic field with respect to the container. A difference in magnetic field strength results in a difference in eddy current, in other words, a difference in heat generation, which causes a defect in adhesive strength. For this reason, the magnetic field strength of the high-frequency induction heating device is periodically measured on the transfer line.
The measuring device disclosed in Patent Literature 1 has a detection unit provided at the top of a dummy container-like case that approximates the outer shape of the actual container, and measures data for setting the seal strength.

However, the material of this container-like case is, for example, an electrical insulator such as ceramic or synthetic resin as a whole, or an electrical insulator such as aluminum alloy at the bottom and ceramic or synthetic resin at the top. It is made of a harder material than the actual container. As a result, the container is likely to come into contact with holders, transport guides, and the like that hold the container on the transport line, resulting in deformation. In addition, the container-like case may be deformed and damaged by repeated use, and there is a risk that foreign matter may enter the transfer line. In addition, although the actual container case is made according to the shape of the actual container, there is a possibility that misalignment may occur due to the difference in hardness on the sealing device, and reproducibility when using the actual container is obtained. There was a risk that errors could occur due to the inability to perform accurate measurements.
For this reason, when measuring the magnetic field strength, there has been an increasing demand for using an actual container that has high reproducibility and is closer to the actual measurement value.

Japanese Patent Application Laid-Open No. 2001-31024

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a magnetic field strength measuring apparatus capable of measuring the magnetic field of a cap seal high-frequency induction heating apparatus using an actual container in view of the above-described problems of the prior art.

As a first means for solving the above problems, the present invention measures the magnetic field strength of a high-frequency induction heating device that generates an induced current while applying a high-frequency magnetic field to the cap of the container to melt and seal the adhesive. In the magnetic field strength measuring device,
a casing that can be inserted into or removed from an upper opening of the container, and has a flange with a larger diameter than the upper opening;
A detection unit provided with a detection coil for measuring an induced current generated when the cap is sealed on the collar, an amplitude detection circuit for converting the measured value of the detection coil, and a hold amplifier for storing the maximum value of the amplitude detection circuit. and the detection unit is provided in the casing.
According to the first means, since the actual container can be applied to the magnetic field measurement of the high-frequency induction heating device, the measured value can be obtained with high reproducibility and very few errors.

As a second means for solving the above-mentioned problems, the present invention provides the first means, wherein the amplitude detection circuit comprises a diode with a small forward voltage and a region requiring measurement in the AC amplitude range to be measured. An object of the present invention is to provide a magnetic field strength measuring device comprising an attenuator for obtaining linearity of detection.
According to the second means, especially when converting from AC to DC, the linearity in the relationship between the detection output and the AC input voltage is improved, and even when the AC input voltage is small, the measurement value of the detection output is also linear. It can be easily converted into voltage with a proportional relationship (a linear conversion area can be secured).

As a third means for solving the above-mentioned problems, the present invention provides a magnetic field strength measuring apparatus according to the first or second means, wherein the hold amplifier uses an ideal diode circuit. It is in.
According to the third means, voltage conversion can be easily performed with a linear proportional relationship, particularly when converting from DC current to DC voltage. In addition, since the leak current is small, discharge of the capacitor is unlikely to occur, and the maximum voltage value can be held for a long time, in other words, the measured value can be held for a long time.

As a fourth means for solving the above problems, the present invention provides a detection coil according to any one of the first to third means, wherein the casing is provided with a groove in which the detection coil is accommodated in the flange. It is another object of the present invention to provide a magnetic field strength measuring device, which is characterized by providing an insulating portion covering the detection coil.
According to the fourth means, the adhesion between the high-frequency induction heating device and the metal cylindrical body is enhanced, so that the measured values can be obtained with reproducibility and little measurement error.

As a fifth means for solving the above-mentioned problems, the present invention provides, in any one of the first to fourth means, wherein the casing comprises the collar and a measuring head formed in a blind hole shape on the collar side. , a columnar substrate cover connected to the measuring head and having the detection unit inside,
The present invention provides a magnetic field strength measuring apparatus, wherein the board cover is made of a material harder than the measuring head, and has a switch and a connection terminal attached to the lower end thereof for connection to the detecting section.
According to the fifth means, the center of gravity of the casing arranged in the actual container is lowered to make it difficult for the casing to overturn easily, so that the casing can be stably conveyed on the production line. In addition, the opening on the bottom side of the casing that does not interfere with the insertion of the container is provided with a power switch and a terminal that is connected to the display unit for outputting measured values and for charging that is connected to the charging unit, providing good operability and handling. .

According to the present invention, since actual containers are used, there is no damage or deformation of the holders or transport guides that hold the containers on the transport line. Further, conventionally, there is no deformation or breakage due to the reuse of the dummy container, and there is no risk of foreign matter entering the transfer line.
Misalignment during the sealing process is eliminated, and measurement values with high reproducibility and very few errors can be obtained.

1 is a schematic configuration diagram of a magnetic field strength measuring device of the present invention; FIG. 3 is a block diagram of a detection unit, a charging unit, and a display unit; FIG. It is explanatory drawing of a casing. 4 is a graph showing the relationship between detection output and AC input voltage; It is explanatory drawing of a measuring head.

An embodiment of the magnetic field strength measuring device of the present invention will be described in detail below with reference to the drawings. INDUSTRIAL APPLICABILITY The present invention is applied to the measurement of the magnetic field strength of a high-frequency induction heating device for cap sealing that fills a container made of plastic such as polystyrene (also called a real container) with a lactic acid bacteria drink or the like on a conveying line, covers the container with an aluminum cap, and then seals the container. It is what is done.

FIG. 1 is a schematic diagram of the configuration of the magnetic field strength measuring device of the present invention. FIG. 2 is a block diagram of the detection section, charging section, and display section. FIG. 3 is an explanatory diagram of the casing. FIG. 4 is a graph showing the relationship between the detected output and AC input voltage. FIG. 5 is an explanatory diagram of the measuring head.
A magnetic field strength measuring apparatus 10 of the present invention comprises a detection section 20 for measuring magnetic field strength, a display section 40 for displaying measured values, and a charging section 50 for charging the detection section 20 and the display section 40 .
[Detection unit 20]
The detector 20 comprises a casing 12 , a detector coil 22 , a substrate 24 and a rechargeable battery 26 .
The casing 12 consists of a measuring head 14 and a substrate cover 16, and is a flanged cylindrical body that can be inserted through the upper opening of the actual container 1 (see FIGS. 1 and 3). The diameter of the cylindrical body of the casing 12 is set to be slightly smaller than the diameter of the top opening of the actual container 1, and the flange 14a is set to have substantially the same diameter as the peripheral portion of the top opening or an enlarged diameter (enlarged diameter). there is
The measuring head 14 (see FIGS. 3 and 5) is a cylinder with a flange 14a and a rechargeable battery 26 inside, and is made of a plastic material such as polyvinyl chloride. The measuring head 14 has a blind hole on the brim 14a side so that it does not come into contact with the equipment on the transfer line inserted from the upper opening side of the actual container 1, and the inside of the casing 12 is cut off. Prevents foreign matter (liquid, etc.) from entering the

The substrate cover 16 (see FIG. 3) is a cylinder joined to the end of the measuring head 14 (the end opposite to the flange 14a), and has a detector 20 inside. The substrate cover 16 is made of stainless steel, which is harder and heavier than the measuring head 14 . As a result, the center of gravity of the casing 12 arranged in the actual container 1 is lowered to make it difficult for the casing 12 to overturn easily, thereby enabling stable transportation on the production line. The lower end of the substrate cover 16 (the side opposite to the side joined to the measuring head 14) is opened to expose the power switch 36 and the terminal 37 for outputting measured values and for charging connected to the display unit 40, which will be described later. It is arranged so that
The detection coil 22 is a coil formed by winding a copper wire or the like having an outer diameter of 0.2 mm to 2.0 mm and having a coil diameter that matches the size of the peripheral portion of the top opening of the actual container 1 . The detection coil 22 (see FIG. 5) is arranged so as to be accommodated (embedded) inside an annular groove 14b provided in the flange 14a of the measuring head 14. As shown in FIG. The groove 14b containing the detection coil 22 is covered with a glass fiber tape that serves as an insulating portion 14c having insulation, abrasion resistance, and heat resistance. Such a detection coil 22 can be mounted on the same plane as the upper surface of the flange 14a without protruding from the groove 14b. A magnetic field can be uniformly applied.

An amplitude detection circuit 30 , a hold amplifier 32 , a voltage monitor/reset controller 34 , a power switch 36 and a terminal 37 are provided on the substrate 24 .
The amplitude detection circuit 30 is electrically connected to the detection coil 22 and supplied with the induced current generated in the detection coil 22 . The amplitude detection circuit 30 rectifies the eddy current (AC) and supplies it to a hold amplifier 32 which will be described later. The amplitude detection circuit 30 of the present embodiment uses a diode with a small forward voltage, for example a Schottky barrier diode, and an attenuator to convert a high-frequency alternating current into a direct current. Here, regarding the relationship between the detection output (V) and the AC input voltage (V), when the AC input voltage is small, the measured value of the detection output becomes extremely small and can be converted into a voltage, as shown by the dotted line in FIG. Can not. Therefore, by using a diode and an attenuator with a small forward voltage, it is possible to obtain a straight line with improved linearity, especially when converting from alternating current to direct current. As a result, even when the AC input voltage is small, the measured value of the detected output can be easily converted into a voltage with a linear proportional relationship (a linear conversion area can be secured).
The hold amplifier 32 is a circuit that converts the DC current into a DC voltage and temporarily stores the largest value in the voltage value signal. The hold amplifier 32 of this embodiment uses an ideal diode circuit. Like the diode and attenuator with a small forward voltage in the amplitude detection circuit 30, the ideal diode circuit facilitates voltage conversion with a linear proportional relationship, especially when converting from DC current to DC voltage.
In addition, by adding a peak hold function to the ideal diode circuit and using a capacitor with a small leakage current, self-discharge of the hold voltage is less likely to occur, and the hold time of the maximum voltage value can be extended, in other words, the measured value can be retained for a long time.
After the measurement is completed, the maximum voltage value stored in the hold amplifier 32 is supplied as an analog voltage to the display unit 40, which will be described later, and displayed digitally.

The voltage monitor/reset controller 34 has a circuit that monitors and warns of a drop in battery voltage, and a hold reset circuit that resets the measured value stored in the hold amplifier 32 . The hold reset circuit is a circuit that resets (deletes) the maximum measured value stored in the hold amplifier 32 upon receiving an ON signal of a power switch, which will be described later.
The power switch 36 is connected to the substrate 24 and arranged so as to be exposed from the lower end of the substrate cover 16 (bottom surface of the casing 12 ) to turn ON or OFF the power supply to the detection unit 20 .
The terminal 37 is a stereo plug that is connected to the substrate 24 and arranged to be exposed from the lower end of the substrate cover 16 (bottom surface of the casing 12). It is also used.
The rechargeable battery 26 is a secondary battery sized to fit within the cylinder of the measuring head 14 . The detection unit 20 can be charged by a charging unit 50, which will be described later, and a nickel-cadmium battery is used as an example.

[Display unit 40]
The display unit 40 is a device that includes a display device 42 and a secondary battery 44 and displays the measured value of the detection unit 20 . The secondary battery 44 is a drive battery for the display device 42 and can be charged by a charging section 50 which will be described later.
[Charging unit 50]
The charging section 50 includes a charging timer 52 and a charging circuit 54 and can charge the detecting section 20 and the display section 40 .
The charge timer 52 is a timer that outputs a signal after a predetermined time has elapsed.
The charging circuit 54 is a circuit that is electrically connected to the charging timer 52 to control constant current and constant voltage charging.

[Action]
The operation of the magnetic field strength measuring apparatus of the present invention having the above configuration will be described below.
The magnetic field intensity measuring device 10 is inserted into the actual container 1 by inserting the casing 12 into the actual container 1 through the upper opening. The magnetic field strength measuring device 10 may be inserted into each of a plurality of real containers 1 that are transported.
When the actual container 1 having the magnetic field intensity measuring device 10 inside passes through the metal cylindrical body on the way of being transferred on the transfer line, an induced current (alternating current) flows through the detection coil 22 due to electromagnetic induction, and this current is The amplitude detection circuit 30 converts to DC. A hold amplifier 32 converts the current into a voltage and stores the maximum voltage value among the voltages. After transportation, the casing 12 (detection unit 20) is taken out from the actual container 1 and connected to the display unit 40, where the measured value is digitally displayed on the display unit 42. FIG.
According to the present invention, since actual containers are used, there is no damage or deformation of the holders or transport guides that hold the containers on the transport line. In addition, deformation or breakage due to the reuse of dummy containers, which has been the case in the past, is eliminated, and there is no risk of foreign matter entering the transfer line.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.
Moreover, the present invention is not limited to the combinations shown in the embodiments, and can be implemented in various combinations.

INDUSTRIAL APPLICABILITY The magnetic field intensity measuring device of the present invention has industrial applicability particularly in the field of manufacturing beverage containers having a high-frequency induction heating device for cap sealing on a conveying line for containers to be filled with lactic acid beverages or the like.

1 Container 10 Magnetic Field Intensity Measuring Device 12 Casing 14 Measuring Head 14a Collar 14b Groove 14c Insulator 16 Substrate Cover 20 Detector 22 Detection Coil 24 Substrate 26 Rechargeable Battery 30 Amplitude Detector 32 Hold Amplifier 34 Voltage Monitor/Reset Controller 36 Power Supply Switch 37 Terminal 40 Display Unit 42 Indicator 44 Secondary Battery 50 Charging Unit 52 Charging Timer 54 Charging Circuit

Claims (5)

A magnetic field strength measuring device for measuring the magnetic field strength of a high-frequency induction heating device that generates an induced current while applying a high-frequency magnetic field to the cap of a container to melt and seal an adhesive,
a casing that can be inserted into or removed from an upper opening of the container, and has a flange with a larger diameter than the upper opening;
A detection unit provided with a detection coil for measuring an induced current generated when the cap is sealed on the collar, an amplitude detection circuit for converting the measured value of the detection coil, and a hold amplifier for storing the maximum value of the amplitude detection circuit. A magnetic field intensity measuring device, comprising: the detecting unit in the casing. The magnetic field strength measuring device according to claim 1,
A magnetic field strength measuring apparatus, wherein the amplitude detection circuit uses a diode with a small forward voltage and an attenuator for obtaining detection linearity in a region requiring measurement in an AC amplitude range to be measured. The magnetic field strength measuring device according to claim 1 or claim 2,
The magnetic field strength measuring device, wherein the hold amplifier uses an ideal diode circuit. A magnetic field strength measuring device according to any one of claims 1 to 3,
A magnetic field intensity measuring apparatus, wherein the casing is provided with a groove for accommodating the detection coil in the flange, and an insulating portion that covers the detection coil accommodated in the groove. A magnetic field strength measuring device according to any one of claims 1 to 4,
The casing comprises a measurement head having a blind hole formed on the flange and the flange side, and a cylindrical substrate cover connected to the measurement head and having the detection section inside,
The magnetic field strength measuring apparatus, wherein the board cover is made of a material harder than the measuring head, and has a switch and a connection terminal attached to the lower end thereof to be connected to the detecting section.

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