JPS6013767Y2 - Container mouth sealing device using high frequency - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a device for sealing the mouth of a container with a metal thin film with a tab by high-frequency induction heating, and particularly relates to an improvement of the device portion for high-frequency induction heating.

As a device for sealing the mouth of a container using high-frequency induction heating, there is a known device such as that shown in Japanese Patent Publication No. 47-50156.

This involves applying a high-frequency current to the coil while pressing the lid, which is made of a thin metal film with a thermoplastic substance adhered to the inner surface, against the container mouth using a pressure plate equipped with a one-turn coil.
The thermoplastic substance is melted by high-frequency induction heating and the lid is bonded to the container opening.

In recent years, in consideration of ease of peeling off after sealing, the shape of the lid has a tab part that partially protrudes from the mouth of the container (hereinafter referred to as a lid with a tab). It is becoming more and more common.

In automatic equipment that uses high frequency to seal the mouth of a container, the position of the gap between the one-turn coil and the tab on the lid is not always constant; Sometimes they overlap.

In that case, the following problems arise.

As shown in Figure 1, the one-turn coil C has a gap G at the feeding point, and at this gap G, the coil C
The magnetic field generated from the line is canceled and no magnetic flux is generated.

When this gap G and the tab portion of the lid overlap, most of the induced current flowing through the lid flows to the side portion of the tab portion, and only a small amount flows to a portion corresponding to the container mouth portion.

Therefore, if the gap G of the coil C overlaps with the tab portion during pressing and heating, the heating effect will be significantly reduced and the tab portion will be incompletely sealed.

This idea was made in view of the above points, and a ferrite for magnetic flux convergence is provided inside the gap of the one-turn heating coil (in other words, inside the feeding point), and the surrounding magnetic flux is reduced to zero by this ferrite. Try to gather it at the point of
It is characterized in that a sufficient heating effect can be obtained even at the location of the gap.

Hereinafter, one embodiment of this invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, the turn coil C is a coil for high frequency induction heating, and a high frequency current is passed therethrough when high frequency induction heating is to be performed.

Ferrite F is provided inside the gap of the coil C (inside the coil C and near the gap between the coils).

The ferrite F is fixed to the predetermined location of the coil C using an adhesive or the like.

If there is no ferrite F, the magnetic fields at the gap of the coil C will cancel each other out and the magnetic flux will be zero, but the ferrite F
When F is provided at the above-mentioned predetermined location, the magnetic flux around the ferrite F is focused on the ferrite F, so that magnetic flux is also generated at the gap portion.

Therefore, sufficient magnetic flux is generated throughout the ring of the coil C to compensate for the gap.

Figure 3 shows the coil C during induction heating and the tabbed lid 1.
0, a diagram showing the positional relationship of the mouth part 11A1 of the container 11,
The coil C is formed by cutting out the pressure plate 12 into a one-turn coil shape, and then forming the remaining ring-shaped portion.

For example, the pressure plate 12 has a thickness of 3oTrr! A plurality of one-turn coils C are formed around the aluminum plate, as shown in FIG.

Incidentally, the interval between the gaps of the coils C is, for example, about 1 m.

A container 11 with a tabbed lid 10 placed on the mouth portion 11A is arranged below the coil C.

A thermoplastic substance is adhered to the inner surface of the tabbed lid 10 (the surface facing the opening 11A), and the container opening 11A is coated with a thermoplastic substance.
A tab portion 10A is formed to partially protrude from the shape of the tab portion 10A.

This tab portion 10A is useful when opening the container mouth portion 11A after it has been sealed with the lid 10.

The lid 10 is pressed against the container opening 1 by the pressure plate 12 containing the coil C.
When a high frequency current is passed through coil C with the pressure at 1A,
An induced current flows through the metal thin film constituting the lid 10, and that portion is heated by high frequency induction.

As a result, the thermoplastic material of the lid 10 melts, and the lid 10 is bonded to the container opening 11A, which is pressed into contact with the lid 10.

FIG. 5a is a plan view showing a case where the tab portion 10A of the lid 10 and the gap G portion of the coil C overlap.

In that case, ferrite F is placed inside the gap G of the coil C.
If it were not provided, as shown in FIG.
Since a large amount of liquid flows around the periphery of the container, heating of the portion B becomes insufficient, and that portion remains without being bonded to the container mouth portion 11A.

In addition, the shaded area in Figures 5c represents the bonded (or welded) surface.

However, if the ferrite F is provided as in this invention, the magnetic flux is also focused in the part corresponding to the gap G, so high-frequency induction heating is performed reliably, and as shown in Figure 5C, the annular bonding is ensured. be done.

Further, the material provided inside the gap of the coil for magnetic flux focusing is not limited to ferrite, and other ferromagnetic materials may be used.

In that case, it goes without saying that consideration must be given to complete insulation from the coil.

As explained above, according to this invention, when a tabbed lid is bonded to a container mouth using a one-turn coil and high-frequency induction heating, it is possible to completely seal the lid.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a one-turn coil to explain the prior art, Fig. 2 is a plan view showing an embodiment of this invention, and Fig. 3 is a coil, tabbed lid, and container mouth during high-frequency induction heating. FIG. 4 is a plan view showing an example of the pressure plate including the coil, and FIG. FIG. 5C is a plan view illustrating the adhesion state when ferrite is not provided, and FIG. 5C is a plan view showing the adhesion state when ferrite is provided according to this invention. C...1 turn coil, F...ferrite, 10...lid with tab, IOA...
Tab portion, 11... Container, 11A... Container opening, 12... Pressure plate.

Claims (1)

[Claims for Utility Model Registration] 1. A lid with a tab made of a thin metal film having a tab portion partially protruding from the mouth of the container and having a thermoplastic substance adhered to the inner surface is continuously fed. A high frequency container mouth sealing device for melting the thermoplastic substance at the mouth of a coming container by high frequency induction heating to seal the container mouth has a large number of slit-like gaps around a circle. a disc-shaped plate having a plurality of holes each forming a one-turn coil, and each of these one-turn coils engaging in a matching manner with the opening of the container to press the steel-lined tabbed lid; a pressure plate; a ferromagnetic material disposed inside the one-turn coil and near the gap; and a power supply means for supplying a high-frequency current to the one-turn coil. Container opening sealing device. 2. A container opening sealing device using high frequency according to claim 1, wherein the ferromagnetic material is ferrite.