Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With means applying wave energy or electrical energy...
Reexamination Certificate
1999-08-10
2001-09-25
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
With means applying wave energy or electrical energy...
C156S380400, C156S530000, C156S581000, C156S274400, C156S309600, C053S451000, C053S479000, C053SDIG002
Reexamination Certificate
active
06294046
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
Priority is claimed with respect to Japanese Application No. 10/225547 filed Aug. 10, 1998, in the Japanese Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat-sealing apparatus for use in a filling/packing machine for producing liquid beverages or the like which are packed in paper containers so that they can be stored for a long time and, more particularly, to a sealing apparatus for transversely heat-sealing a tubular packing material filled with contents, such as liquid beverages, together with fluid.
2. Description of the Related Art
Conventionally, when producing a packing container having a box shape filled with a liquid such as juice that is to be sealed, as shown in Japanese Patent Publication No. 3215/1980, it is well known to use a sealing apparatus in which a packing material including a laminate of paper, aluminum foil and a synthetic resin is continuously formed into a tubular shape while being conveyed. As shown in
FIG. 1
, the tubular packing material
1
is transversely heat-sealed with fluid by using pressing means including a sealing jaw
3
having a high-frequency coil
2
and an opposing jaw
5
having a sealing rubber
4
of hard rubber. Tubular material
1
is cut between two sealed zones having been heat-sealed by a cutting blade
6
.
In Publication of Japanese Patent application Laid-Open Nos. 134744/1983, 269854/1993, 164523/1995 and 218805/1996, there is further disclosed a heat-sealing apparatus for heat-sealing a laminate material in which a ridge is formed on the pressing face of a high-frequency coil on a sealing jaw in the aforementioned heat-sealing apparatus so that molten resin is extruded into a sealed zone by the ridge.
In known heat-sealing apparatus, when molten resin is guided to flow toward a container's interior side of the sealed portion of a tubular packing material, corrugated molten resin beads are formed on the edge portion of the container's interior side so that cracks start from the crests of the beads to break the container when an external force is applied to the container. In order to avoid the above problem of the aforementioned heat-sealing apparatus, two magnetic members are arranged on the outer side (or the container's interior side) of the straight portions of a U-shaped high-frequency coil to leave a portion of the container's inner side unheated, as disclosed in Japanese Patent No. 2571977.
In the Publication of Japanese Patent Application Laid-Open No. 230834/1996, a high-frequency coil having a ridge in its longitudinal direction and grooves formed on the two sides of and in parallel with the ridge causes melted resin to remain in the grooves. Thus, the melted resin does not flow out of a sealed zone, even if the resin on the packing material is melted and pushed by the ridge. It is further described in heat-sealing apparatus of the prior art which do not have an aforementioned groove that the molten resin having flowed out of a sealed zone solidifies to stick to the interior side of a packing container thereby forming cracks during a shaping process after the sealing step.
In the Publication of Japanese Patent Application Laid-Open No. 244728/1996, on the other hand, a high-frequency coil which is inclined gradually at a greater distance than the sealed zone forming portion goes to the outer side (to the container's interior side) is employed so that the tube is heat-sealed whereby liquid and molten resin are discharged smoothly from the sealed zone to the container inner side, when the tube is pressed together with fluid.
In order to effect an excellent heat-sealing in a sealing apparatus for transversely heat-sealing a tubular packing material filled with contents such as a liquid beverage in the presence of the liquid, it is necessary to exclude the liquid from the sealed zone of the tube as much as possible when the tube is sealed with heat and under pressure. However, the inner face of a tube which is in contact with the liquid is not completely flat and has small irregularities, if observed in detail. In the heat-sealing apparatus disclosed in the aforementioned Publication of Japanese Patent Application Laid-Open Nos. 134744/1983, 269854/1993, 164523/1995, 240607/1997 or 230834/1996, a sealing method is adopted in which the molten resin can be prevented from flowing out of the sealed zone so that it remains in the sealed zone. Therefore, any liquid or dirt which may have entered the small irregularities in the tube inner face cannot be discharged to the outside of the sealed zone so that the sealing property cannot be said to be sufficient.
On the other hand, the inventors of this invention have discovered that any liquid in the sealed zone may be guided to flow out together with the molten resin to the outside of the sealed zone so as to clear the liquid or dirt in the irregularities when sealed, and have competed the invention, as disclosed in the aforementioned Publication of Japanese Patent Application Laid-Open No. 8-244728. The method using this heat-sealing apparatus can clear the liquid or dirt in the irregularities completely to provide an excellent sealing property, but the molten resin having flowed out to the container's interior side may not be homogeneously extruded. As shown in
FIG. 2
, undulating molten resin beads
7
are formed on the edge portion of the container's interior side. During a secondary step using a shaping machine after the sealing step, it has been found out that cracks start from crests
8
of the undulations of the beads
7
to cause liquid leakage although not frequently when a pressure is applied to the container.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a heat-sealing apparatus capable of solving the aforementioned problems of the heat-sealing apparatus in the prior art, that is, a heat-sealing apparatus capable of ensuring sufficient fluidity of a resin without deteriorating the compression strength of the container. Specifically, the object is to provide a heat-sealing apparatus capable of: achieving a complete sealing property by causing any liquid or dirt that may have entered small irregularities in the tube inner face to flow out of the sealed zone together with the molten resin, and a heat seal with an excellent compression strength, as the seal is free from cracks caused by the molten resin having flowed in to a container's interior side.
The inventors of the present invention have developed a high-speed filling machine (Publication of Japanese Patent Application Laid-Open No. 86915/1998) provided with a sealing apparatus for transversely heat-sealing a tubular packing material, which is filled with contents such as a liquid beverage, together with fluid. The heat-sealing apparatus in this high-speed filling machine is not provided with a sealing jaw having both a heat-sealing portion and a cutting portion, unlike the aforementioned heat-sealing apparatus, but is provided with a cutting portion
10
for the step following sealing portion
9
, as shown in FIG.
3
. It follows, as shown in
FIG. 4
, that the heat-sealing apparatus used in the aforementioned high-speed filling machine is composed of a sealing jaw
3
having a high-frequency coil
2
and an opposed jaw
5
having a sealing rubber
4
but is not equipped with any cutting mechanism. In this heat-sealing apparatus
11
, however, the pressure is applied to the whole face including a zone to be sealed so that the flow of the molten resin cannot be sufficient for achieving a complete seal. According to this known heat-sealing apparatus, any liquid which may have entered the small irregularities in the tube inner face is to be completely discharged together with the molten resin to the outside of the sealed zone. The flow of the liquid and molten resin is directed only to the container's interior side. With this inflow to the container's interior side, the corrugated
Katayama Hiroshi
Kume Satoshi
Ueda Michio
Ball Michael W.
Kinberg Robert
Shikoku Kakoki Co. Ltd.
Tolin Michael A.
Venable
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