JP2020112512A - Magnetic field strength measuring device - Google Patents

Abstract

To provide a magnetic field strength measuring device capable of measuring a magnetic field of a cap seal high frequency induction heating device using a real container.SOLUTION: A magnetic field strength measuring device 10 measures a magnetic field strength of a high frequency induction heating device that generates an induction current while applying a high frequency magnetic field to a cap of a container 1 to melt an adhesive agent to perform sealing, and includes: a casing 12 which is insertable or detachable from an upper surface opening of the container 1 to an inside and has a flange 14a whose diameter is larger than that of the upper surface opening; an amplitude detecting circuit 30 in which a detecting coil 22 for measuring an induced current generated when the cap is sealed is provided at the flange 14a and which converts a measured value of the detecting coil 22; and a detection unit 20 which has a hold amplifier 32 for storing the maximum value of the amplitude detection circuit 30, wherein the detection unit is provided in the casing 12.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a device for measuring the magnetic field strength of a cap sealing device for a container, which uses heat generated by generation of an electromagnetic induction current (eddy current) in a container such as a lactic acid bacterium beverage.

A production line of a container for filling a lactic acid beverage or the like has a sealing step using a high-frequency induction heating device for a cap seal in which the container is filled with the lactic acid beverage or the like and then sealed with an aluminum cap.
In this sealing step, first, an upper surface opening of the container is covered with an aluminum cap in which a heat-melting adhesive is applied in advance on the surface of the container to be bonded. Then, while the high-frequency magnetic field is applied from above by the metal tubular body, the container is pressed upward by the pressing means from below. At this time, an eddy current is generated in the aluminum cap by the electromagnetic induction action, and the temperature of the aluminum cap is raised by the eddy current and the heat generation action of the specific resistance of the aluminum cap to melt and seal the adhesive. On the transfer line, a configuration is employed in which a plurality of combinations of a metal tubular body and a pressing unit are provided so that a plurality of containers can be sealed.

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

However, the material of this container-like case is made of ceramic, synthetic resin, or other electrical insulator, or the lower part is made of aluminum alloy and the upper part is made of ceramic, synthetic resin, or other electrical insulator. It is made of a harder material than the real container. Then, the holder is likely to come into contact with a holder for holding the container or the conveying guide in the conveying line, and the deformation easily occurs. Further, the container-like case may be deformed and damaged by repeated use, and foreign matter may be mixed into the transport line. Although the actual container case is made according to the shape of the actual container, there is a possibility of core misalignment due to the difference in hardness on the sealing device, and the reproducibility when using the actual container is obtained. As a result, accurate measurement cannot be performed and errors may occur.
Therefore, when measuring the magnetic field strength, there is an increasing demand for using an actual container that has high reproducibility and is closer to the actual measured value.

JP 2001-31024 A

The problem to be solved by the present invention is to provide a magnetic field strength measuring device capable of measuring a magnetic field of a high-frequency induction heating device for a cap seal by using an actual container in view of the above-mentioned 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 apparatus that melts and seals an adhesive by generating an induction current while applying a high-frequency magnetic field to a cap of a container. In the magnetic field strength measuring device,
A casing having a brim having a diameter larger than that of the top opening, which is insertable into or removable from the top opening of the container.
A detection coil is provided in the collar for measuring an induced current generated when the cap is sealed, and an amplitude detection circuit for converting a measurement value of the detection coil, and a detection unit having a hold amplifier for storing the maximum value of the amplitude detection circuit A magnetic field strength measuring device comprising:
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 measurement value having high reproducibility and extremely small error can be obtained.

The present invention provides, as a second means for solving the above-mentioned problems, in the first means, the amplitude detection circuit includes a diode having a small forward voltage and a region of the AC amplitude range in which measurement is required. It is an object of the present invention to provide a magnetic field strength measuring device characterized by being composed of an attenuator for obtaining detection straightness.
According to the second means, particularly 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 linear. The voltage can be easily converted in a linear relationship (a linear conversion area can be secured).

As a third means for solving the above problems, the present invention provides a magnetic field strength measuring device according to the first or second means, wherein the hold amplifier uses an ideal diode circuit. It is in.
According to the third means, in particular, when converting a direct current into a direct current voltage, voltage conversion can be facilitated in a linear proportional relationship. Further, since the leak current is small, the capacitor is less likely to be discharged, and the hold time of the maximum voltage value is long, that is, the measured value can be held long.

The present invention provides, as a fourth means for solving the above-mentioned problems, in any one of the first to third means, the casing is provided with a groove for accommodating the detection coil in the collar, and is accommodated in the groove. An object of the present invention is to provide a magnetic field strength measuring device characterized in that an insulating portion for covering the detection coil is provided.
According to the fourth means, the close contact with the metal tubular body of the high-frequency induction heating device is enhanced, reproducibility, and a measured value with less measurement error can be obtained.

The present invention provides, as a fifth means for solving the above-mentioned problems, in any one of the first to fourth means, the casing includes the brim and a measuring head formed in a blind hole shape on the brim side. A columnar substrate cover that has the detection portion inside by being connected to the measurement head,
It is an object of the present invention to provide a magnetic field strength measuring device characterized in that the substrate cover uses a member harder than the measuring head, and has a switch connected to the detection unit and a connection terminal on the lower end side.
According to the fifth means, the center of gravity of the casing arranged in the actual container is lowered to make it difficult to fall over easily, and stable transportation can be performed on the manufacturing line. Also, a power switch and a terminal for both output of measured values connected to the display and for charging connected to the charging section are provided in the opening on the bottom side of the casing that does not interfere with the insertion of the container, and operability and handling are good. ..

According to the present invention, since the actual container is used, the holder or the transfer guide for holding the container on the transfer line is not damaged or deformed. Further, conventionally, there is no deformation or damage due to reuse of the dummy container, and there is no risk of foreign matter entering the transport line.
There is no misalignment during the sealing process, the reproducibility is high, and the measured values with very few errors can be obtained.

It is a schematic diagram of a magnetic field strength measuring device of the present invention. It is a block diagram of a detection part, a charging part, and a display part. It is explanatory drawing of a casing. It is a graph which shows the relationship between a detection output and an alternating current input voltage. It is explanatory drawing of a measuring head.

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

FIG. 1 is a schematic configuration diagram of a magnetic field strength measuring apparatus of the present invention. FIG. 2 is a block diagram of the detection unit, the charging unit, and the display unit. FIG. 3 is an explanatory diagram of the casing. FIG. 4 is a graph showing the relationship between the detection output and the AC input voltage. FIG. 5 is an explanatory diagram of the measuring head.
The magnetic field strength measuring device 10 of the present invention includes a detection unit 20 that measures a magnetic field strength, a display unit 40 that displays a measurement value, and a charging unit 50 that charges the detection unit 20 and the display unit 40.
[Detection unit 20]
The detection unit 20 includes a casing 12, a detection coil 22, a substrate 24, and a rechargeable battery 26.
The casing 12 includes a measuring head 14 and a substrate cover 16, and is a flanged cylindrical body that can be inserted from an 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 shorter than the diameter of the upper opening of the actual container 1, and the brim 14a is set to a diameter substantially the same as the peripheral portion of the upper opening or an enlarged diameter (expansion). There is.
The measuring head 14 (see FIGS. 3 and 5) is a cylinder with a brim 14a and a brim 14a having a rechargeable battery 26 inside, and is made of a plastic material such as polyvinyl chloride. The measuring head 14 is formed in a bag hole shape on the side of the flange 14a so as not to come into contact with a device or the like on the transfer line inserted from the upper surface opening side of the actual container 1, and is cut off so that the inside of the casing 12 is closed. Prevents foreign substances (liquid, etc.) from entering.

The substrate cover 16 (see FIG. 3) is a cylinder that is joined to the end of the measurement head 14 (the end opposite to the brim 14a), and has the detector 20 inside. The substrate cover 16 is made of stainless steel and 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 fall over easily, so that stable transportation can be performed on the manufacturing line. The lower end of the substrate cover 16 (the side opposite to the side where it is joined to the measuring head 14) is opened, and the power switch 36 and a terminal 37 for both measurement value output and charging, which is connected to a display section 40 described later, are exposed. It is arranged to.
The detection coil 22 is a coil in which a copper wire or the like having an outer diameter of 0.2 mm to 2.0 mm is wound once and the coil diameter is matched with the size of the peripheral portion of the upper surface opening of the actual container 1. The detection coil 22 (see FIG. 5) is arranged so as to be housed (embedded) inside the annular groove 14b provided in the brim 14a of the measurement head 14. The groove 14b accommodating the detection coil 22 is covered with a glass fiber tape serving as an insulating portion 14c having insulating properties, abrasion resistance, and heat resistance. The detection coil 22 as described above can be mounted on the same plane as the upper surface of the brim 14a without protruding from the groove 14b, the adhesion to the metal tubular body of the high frequency induction heating device is enhanced, and the high frequency wave from the metal tubular body is increased. A magnetic field can be applied uniformly.

An amplitude detection circuit 30, a hold amplifier 32, a voltage monitoring/reset control section 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 is 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 described later. The amplitude detection circuit 30 of this embodiment uses a diode having a small forward voltage, for example, a Schottky barrier diode, and an attenuator to convert high frequency alternating current into direct current. Here, the relationship between the detection output (V) and the AC input voltage (V) is such that when the AC input voltage is small as shown by the dotted line curve in FIG. 4, the measured value of the detection output is extremely small and can be converted into a voltage. Can not. Therefore, by using a diode and an attenuator having a small forward voltage, a straight line such as a solid line with improved linearity can be formed especially when converting from AC to DC. As a result, even when the AC input voltage is small, the measured value of the detection output can be easily converted into a voltage in a linear proportional relationship (a linear conversion region can be secured).
The hold amplifier 32 is a circuit that converts a 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. The ideal diode circuit, like the diode and attenuator having a small forward voltage of the amplitude detection circuit 30, can easily perform voltage conversion in a linear proportional relationship particularly when converting a direct current to a direct voltage.
Further, by adding a peak hold function to the ideal diode circuit and using a capacitor with a small leak current, self-discharge of the hold voltage does not easily occur, and the hold time of the maximum voltage value can be lengthened, in other words, the measured value can be held long.
The maximum voltage value stored in the hold amplifier 32 is supplied to the display unit 40, which will be described later, as an analog voltage and digitally displayed after the measurement.

The voltage monitoring/reset control unit 34 has a circuit that monitors and warns the battery voltage drop, and a hold reset circuit that resets the measured value stored in the hold amplifier 32. The hold reset circuit is a circuit that receives an ON signal of a power switch described later and resets (erases) the maximum measurement value stored in the hold amplifier 32.
The power switch 36 is connected to the substrate 24 and is arranged so as to be exposed from the lower end of the substrate cover 16 (bottom surface of the casing 12) to turn ON/OFF the power supply to the detection unit 20.
The terminal 37 is a stereo plug that is connected to the board 24 and is arranged so as to be exposed from the lower end of the board cover 16 (bottom surface of the casing 12 ). It is used for outputting the measurement value of the detecting section 20 and for charging the charging section 50. I also use it.
The rechargeable battery 26 is a secondary battery that fits inside the cylinder of the measuring head 14. The detection unit 20 can be charged by a charging unit 50 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 42 and a secondary battery 44 and that displays the measurement value of the detection unit 20. The secondary battery 44 is a drive battery for the display 42 and can be charged by the charging unit 50 described later.
[Charging unit 50]
The charging unit 50 includes a charging timer 52 and a charging circuit 54, and can charge the detection unit 20 and the display unit 40.
The charging 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 and can perform constant current and constant voltage charging control.

[Action]
The operation of the magnetic field strength measuring device of the present invention having the above configuration will be described below.
The casing 12 is inserted into the real container 1 through the upper surface opening so that the magnetic field intensity measuring device 10 is inserted into the real container 1. It may be inserted into each of the plurality of actual containers 1 that carry the magnetic field strength measuring device 10.
When the actual container 1 having the magnetic field intensity measuring device 10 inside is transferred on the transfer line while passing through the metal cylindrical body, an induction current (AC) flows through the detection coil 22 by an electromagnetic induction action, and this current is The amplitude detection circuit 30 converts to direct current. The hold amplifier 32 converts the current into a voltage and stores the maximum voltage value of the voltage. After the transportation, the casing 12 (detection unit 20) is taken out from the actual container 1, connected to the display unit 40, and the measured value is digitally displayed on the display unit 42.
According to the present invention, since the actual container is used, there is no damage or deformation of the holder or the transfer guide that holds the container on the transfer line. Further, there is no deformation or damage resulting from the reuse of the dummy container which has been present in the past, and there is no possibility that foreign matter is mixed in on the transfer line.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
Further, the present invention is not limited to the combinations shown in the embodiments and can be implemented by various combinations.

INDUSTRIAL APPLICABILITY The magnetic field strength measuring device of the present invention has industrial applicability particularly in the field of manufacturing a beverage container equipped with a high-frequency induction heating device for a cap seal on a transport line of a container for filling a lactic acid bacterium beverage or the like.

1 Container 10 Magnetic Field Strength Measuring Device 12 Casing 14 Measuring Head 14a Collar 14b Groove 14c Insulating Part 16 Substrate Cover 20 Detecting Unit 22 Detecting Coil 24 Substrate 26 Rechargeable Battery 30 Amplitude Detection Circuit 32 Hold Amplifier 34 Voltage Monitoring/Reset Control Unit 36 Power Supply Switch 37 Terminal 40 Display 42 Display 44 Secondary battery 50 Charging unit 52 Charging timer 54 Charging circuit

Claims (5)

In the magnetic field strength measuring device for measuring the magnetic field strength of the high frequency induction heating device that melts and seals the adhesive by generating an induction current while applying a high frequency magnetic field to the container cap,
A casing having a brim having a diameter larger than that of the top opening, which is insertable into or removable from the top opening of the container.
A detection coil is provided in the collar for measuring an induced current generated when the cap is sealed, and an amplitude detection circuit for converting a measurement value of the detection coil, and a detection unit having a hold amplifier for storing the maximum value of the amplitude detection circuit And a magnetic field intensity measuring device comprising the detecting unit in the casing. The magnetic field strength measuring device according to claim 1,
The magnetic field strength measuring device characterized in that the amplitude detection circuit uses a diode having a small forward voltage and an attenuator for obtaining detection linearity in a region requiring measurement in an AC amplitude range for measurement. The magnetic field strength measuring device according to claim 1 or 2, wherein
The magnetic field intensity measuring device, wherein the hold amplifier uses an ideal diode circuit. The magnetic field strength measuring device according to any one of claims 1 to 3,
The casing is provided with a groove for accommodating the detection coil in the collar, and an insulating portion for covering the detection coil housed in the groove is provided. The magnetic field strength measuring device according to any one of claims 1 to 4,
The casing comprises a cylindrical head cover having the brim and the brim side formed in a bag-hole shape, and the measuring head connected to the measuring head and having the detecting section therein.
The magnetic field strength measuring device characterized in that the substrate cover is made of a member harder than the measuring head, and a switch connected to the detection unit and a connection terminal are attached to the lower end side.

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