JPS62208326A - Bell-jar structure for vacuum-packaging product, particularly, food product, by flexible plastic film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bell jar structure for vacuum packaging products, especially food products, with flexible plastics films.

Bell jars for vacuum packaging products with mechanically and/or thermally deformable flexible plastic films are disclosed, for example, in my U.S. Pat. , 950,919, the bell jar consists of a body portion defining a downwardly open swinging cavity, the body portion having a plurality of passageways extending therein, e.g. It has a working surface with a number of holes that can be connected to a suction device such as a pump. The rocking cavity has a sealing edge which rests on a substantially horizontal surface and which can be moved to place a dish on which the product to be packaged can be placed over the flexible film. Place it on the board. When this bell jar is heated at any time on its working surface, it stretches the film by the suction effect through its numerous holes, while at the same time creating a constant vacuum between the upper film and the generally rigid lower film. Gradually relaxing the upper film, which acts as a preform into the pan, causes the film to stick to the product, and due to the vacuum created between the film and the pan, the upper film fuses to the pan. , a vacuum packaged product is obtained.

Although such conventional bell jar designs are capable of packaging products at high speeds, they still have several drawbacks, primarily those caused by the shape of the rocking cavity.

In fact, the working surface usually consists of a top and a side, the top lying on a plane substantially parallel to the plane defined by the sealing lip, and the sides extending generally perpendicularly from the top towards the sealing lip. ing.

With this shape, applying a vacuum through the large number of holes places uneven stresses on the surface of the film, particularly at the junctions between the sides and the top. Considering that the film stretching and heating process takes place on the order of a few seconds, these highly stressed bond areas are not heated to the same extent as the rest of the film, causing the film to be exposed to the working surface. This is undesirable in that it prevents rapid adhesion.

If the film is heated and stretched unevenly, the packaging will be defective and the film surface will wrinkle, making the seal unreliable.

Another problem caused by uneven stress on the film is that to avoid excessive stress at the point of highest tension, the gap between the top of the working surface and the sealing edge of the bell jar must be reduced. This is something that must be restricted. For this reason, the height of the conventional bell-kai jar is 80 to 85 mm.
It is unsuitable for packaging products that weigh more than one layer.

The main object of the present invention is to overcome the drawbacks of the above-mentioned prior art methods by providing a vacuum packaging bell jar configured to uniformly stretch and heat the film covering the product to be packaged. .

Within the scope of the above objects, it is another object of the invention to provide bell jars of conventional design with a wide gap between the top of the working surface and the sealing edge, thereby facilitating the production of relatively thick products. An object of the present invention is to provide a bell fist jar that can be packaged.

The foregoing and other objects will become apparent from the following description, comprising a body having a sealing edge defining a downwardly open rocking cavity and extending substantially in a plane circumferentially thereof; The dynamic cavity has a working surface perforated with a number of holes connectable to a suction device, a top portion lying in a plane substantially parallel to a plane defined by the sealing edge, and a top portion extending from the top portion to the sealing portion. lateral parts extending to an edge, the lateral parts overlying a set of surfaces that are different from each other with respect to the plane defined by the sealing edge and at an angle of inclination that decreases from the sealing edge to the top. Achieved by providing a bell jar structure for vacuum packaging products, in particular food products, with a flexible plastics film, characterized in that it consists of at least one first zone and a second zone. be done.

BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the present invention will become apparent from the following detailed description of a bell jar for packaging, which is an embodiment of the structure of the present invention, with reference to the accompanying drawings.

Referring to the accompanying drawings, the bell jar of the present invention, indicated generally at 1, defines a downwardly open swinging cavity 3, bounded by a substantially coplanar sealing edge 4. It consists of two metal bodies.

The swinging cavity 3 preferably has a substantially rectangular contour in order to fit packaging devices of known design, but
It has a working surface pierced with a number of holes 5, which are arranged in such a way that they are connected to a conventional suction device via a reticular passageway 6 extending inside the body 2. It communicates with conduit 7.

The working surface consists of a top part 8 lying on a plane substantially parallel to the plane of the sealing edge and a side part extending from the top part as far as possible towards the sealing edge.

According to the invention, this side part consists of at least one first section 9 and at least one second section 10, which sections have different angles of inclination with respect to the plane of the sealing edge. The angle of inclination decreases from the sealing edge toward the top.

In fact, the first zone 8 has a smaller angle of inclination to the plane of the sealing edge than the second zone 10, so that the active surface is evacuated in the rocking cavity and the sealing edge It can have a shape similar to the shape of the surface of the membrane placed on it.

More specifically, the first area 9 near the top has an angle of inclination of substantially 30 to 80° with respect to the plane of the sealing edge;
Its height is substantially less than or equal to 2/3 of the distance from the top to the sealing edge.

lla and 11b, respectively, to eliminate sharp corners on the working surface.
A curved portion is provided to connect the first and second portions and the top to each other.

Furthermore, in order to achieve good and rapid adhesion of the film to the working surface, the number of holes 5 should extend close to the area where the first and second areas merge and very close to the sealing edge. Advantageously, they are arranged.

Of course, on the sides of the working surface, with respect to the plane defined by the sealing edge, it is possible to provide several areas with a slope setting that gradually decreases towards the top, but the construction of the bell jar is more complex. It will be.

The fuselage 2 also includes a housing 12 for a heating device, such as an electric resistance heater.

For completeness of explanation, the mesh-like passage 5 can be produced very simply by drilling holes in the body and plugging the outer holes with special plugs 13.

The operating power of the bell jar of the present invention will be apparent from the above description.

Place the bell jar 1 above a conventional board 14 and place the product to be packaged 1ee on the board 15 0 Mechanically and thermally deformable flexible plastics film material For example, a film 17 made from a polyethylene-based plastic film is used as product 1B.
The first sealing gasket 1 is placed around the 0 plate spread on top.
8 is provided, which gasket is connected to a corresponding second sealing gasket 1 attached to the sealing edge 4 of the bell jar.
It is paired with 9. The dish also has holes connected to conduits 20 and 21, which are connected to a conventional suction device.

The bell jar l is then lowered onto the plate 14, and the suction effect draws the film onto the working surface of the rocking cavity 3, resulting in uniform stretching and heating, during which time there is a gap between the mold and the film. After some air is removed through conduits 20 and 21, the pressure applied to the bell jar 1 is gradually increased to move the film downwardly into tight contact with the product and the dish, completing the process of vacuum packaging the product. Thereafter, the bell jar 1 is lifted up and the packaged product is taken out.

As a practical matter, a bell jar using the structure of the invention has a good uniformity of stretching and heating of the film due to its shape, thus ensuring proper adhesion between the film and the product and avoiding wrinkles and improper It has been found that it is possible to ensure that there are no sealed areas, which is sufficient to achieve the purpose.

Another advantage is that because of the uniformity provided by the present invention, it is possible to provide bell jars that are taller than conventional ones without the risk of tearing or unduly weakening the film. be.

In carrying out the invention, the materials and dimensions used can be any according to the requirements of the application and the state of the art.

[Brief explanation of drawings]

FIG. 1 is a partially removed top plan view of the bell jar of the present invention, and FIG. 2 is a top plan view of the bell jar of the present invention taken along line II-II.
FIG. 3 is a cross-sectional view of FIG. 1 taken along the line III--III. Figures 4 and 5 are enlarged detail views of Figure 3, and Figures 8-8 are schematic cross-sectional views of the bell fist jar at various stages of operation.

Claims (1)

[Claims] 1. Consists of a body having a sealing edge defining a downwardly open swinging cavity and extending circumferentially substantially in one plane, said swinging cavity being adapted to a suction device. a top having a working surface drilled with a plurality of connectable holes and lying in a plane substantially parallel to a plane defined by the sealing edge; and a side extending from the top to the sealing edge. and at least one first area on a set of surfaces different from each other with respect to the plane defined by the sealing edge and at an angle of inclination that decreases from the sealing edge to the top. and a second zone. 2. The bell jar structure according to claim 1, wherein the area of the side part and the top part are radial parts connected to each other by a curved part. 3. the first section extends from the top to the second section;
Claim 1 having a height substantially less than or equal to two-thirds of the distance from the top to the sealing edge.
The bell jar structure described in Section 1. 4. Any one of claims 1 to 3, which includes a large number of holes drilled in the working surface and existing in the vicinity of the part where the first area and the second area merge. The bell jar structure described. 5. A bell jar structure according to claim 1, wherein the first section of the side surface has an inclination angle of between 30 and 60 degrees on the plane defined by the sealing edge. 6. A bell jar structure according to claim 1, including a device for heating the body. 7. The bell jar structure of claim 1, wherein said swinging cavity has a substantially rectangular profile.