SEALING DEVICE FOR A TRAY SEALER

Abstract

A sealing device for sealing trays, the sealing device having a sealing-tool lower part and a sealing-tool upper part. The sealing-tool lower part includes a tray holder. The sealing-tool upper part includes a sealing plate and a cutting knife The tray holder includes a cutting channel into which the cutting knife can dip or, in other words, that may receive the cutting knife, when cutting a film lid for the tray from the film web, the film lid being sealed on the tray.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to German Application Number 102012012481.3 filed Jun. 22, 2012, to Jurgen Prasenz and Jochen Make entitled “Sealing Device for a Tray Sealer,” currently pending, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a sealing device for a tray sealer to seal trays containing products with a film web, such as food articles, as well as to a method of operating such a sealing device.

BACKGROUND OF THE INVENTION

DE 10 2005 035 476 A1 discloses a sealing device in which a film web is clamped on a sealing-tool upper part by a clamping plate. A cutting knife arranged in the sealing-tool upper part carries out a cutting movement such that the cutting knife dips into an opening provided in the clamping plate and cuts a piece of film out of the film web before the film is attached to a tray edge and sealed, by use of a sealing plate. In this known inside-cut process, the film is cut prior to being sealed such that the dimensions of the cut film correspond to the sealed area so that the film does not extend up to the outermost edge of a tray, and no film or only a very small part of the film projects beyond the sealed seam after sealing. This technique forms a package having pleasing and neat appearance. Since the film web extends between the sealing-tool upper part and the clamping plate and is pinched therebetween, the clamping plate is resiliently guided in the sealing-tool upper part. This embodiment makes it difficult to thread in a new film web after a change of films, and is in some cases obstructive insofar as the residual film grid of the film web may get stuck during film transport. In addition, if process irregularities occur, such as a product projecting beyond the tray edge of a tray, and the sealing device presses the product against the clamping plate, then the clamping plate may be easily damaged.

Other sealing devices are known in the art, such as those described in DE 10 2006 061 309 A1, DE 102 37 933 A1, or DE 10 2008 057 609 A1.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an improved sealing device of a tray sealer and a method of operating such a sealing device, which avoid the above shortcomings in the art.

The sealing device according to the present invention comprises a sealing-tool lower part and a sealing-tool upper part, the sealing-tool lower part including a tray holder and the sealing-tool upper part including a sealing plate and a cutting knife The sealing device may include the tray holder having a cutting channel integrated therein and the cutting knife can dip or be inserted into the cutting channel for cutting a film web. This cutting channel may be defined in that the tray holder includes a reception area as a support for an edge of a tray to be sealed and in that said reception area may be offset by at least five millimeters (5 mm) in a direction away from the sealing-tool upper part relative to a support surface (or bearing surface) on which the film web of the top film can rest outside of the tray. Thus, a cutting channel may be formed, which does not merely extend as an annular track around the tray, but into which the tray can be immersed as a whole. This provides the enormous advantage that a clamping plate, which has previously been resiliently attached to the sealing-tool upper part by means of guide units, may no longer be required in a sealing device. The present sealing device can be implemented with a simpler structural design and enhanced process reliability, and the film web need no longer be threaded in, but can simply be passed between the sealing-tool upper part and the sealing-tool lower part in the open condition of the tool.

According to one embodiment, the cutting channel is substantially arranged concentrically with or may be congruent with the reception area of the tray holder so that a package having an aesthetic appearance can be produced.

Another embodiment includes parallel to a direction of movement of the cutting knife, a distance of three-tenths of one millimeter (0.3 mm) to three millimeters (3 mm) may be provided between the cutting knife and the edge of the cutting channel so as to guarantee a high film cutting quality.

The cutting channel may be arranged above the reception area for an edge of the tray to be held so as to prevent the cutting knife from coming into contact with the tray.

The dimension of the cutting channel corresponds at least to the external dimension of a tray.

Preferably, the tray holder includes a plurality of cutting channels so that a multiple split-up tool (i.e. a tool for simultaneously processing a plurality of trays) can be provided for accomplishing a high packaging performance.

In further embodiments of the present sealing device may include the offset of the reception area relative to the support surface being at least six millimeters (6 mm), and preferably six millimeters (6 mm) to ten millimeters (10 mm), in a direction away from the sealing-tool upper part. Tests have shown that an offset in the range of eight millimeters (8 mm) to nine millimeters (9 mm), in particular eight and one-half millimeters (8.5 mm), may be particularly advantageous.

A method according to the present invention for operating the above-described sealing device may include cutting of the film web using the cutting knife dipped or inserted into the cutting channel of the tray holder; therefore, this method does not require the use of a clamping plate.

The film web may be pinched or compressed between the sealing-tool upper part and the tray holder before it is cut, so as to support the cutting process and allow evacuation of the chamber defined by the sealing-tool upper part and the sealing-tool lower part.

Preferably, the cutting knife remains above a sealing plane when the film web is cut in the cutting channel, but other configurations may be used.

According to another embodiment, the cut film may be taken hold of by the sealing plate, when the latter moves towards the tray holder, and pinched or compressed onto the tray, so as to seal the film onto the tray in the sealing plane for allowing film dimensions that project only a small distance beyond the sealed seam. This configuration may provide the benefit of producing a package having an aesthetic appearance.

Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:

FIG. 1 is a side view of a sealing device of a tray sealer in accordance with one embodiment of the present invention at an open position;

FIG. 2 is a side view of the sealing device of the tray sealer of FIG. 1 at a closed position;

FIG. 3 is a side view of the sealing device of the tray sealer of FIG. 1 at a position for cutting a film from a film web;

FIG. 3a is a blown up detailed side view of the cutting channel of the sealing device of the tray sealer of FIG. 1;

FIG. 4 is a side view of the sealing device of the tray sealer of FIG. 1 during the process of sealing the film onto a tray; and

FIG. 5 is a side view of a tray after being sealed by the sealing device of the tray sealer of

FIG. 1.

Identical components are provided with identical reference numerals throughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

FIG. 1 shows a side view as a section through a sealing device 1 according to the present invention at an open position. A sealing-tool upper part 3 is arranged above a film/foil web 2. In the interior of the sealing-tool upper part 3 a cutting knife 4 and a sealing plate 5 are provided, which are each independently movable in a vertical direction relative to one another and to the sealing-tool upper part 3.

A sealing-tool lower part 6 including a tray holder 7 is arranged below the film web 2.

The tray holder 7 is provided for accommodating two trays 8, the trays 8 being placed with their tray edge 9 (best shown in FIG. 5) onto a reception area 10 of the tray holder 7 by means of a gripper system, which is not shown. The reception area 10 is provided with a silicone gasket 11 so as to support the process of sealing the film web 2 to the tray 8. The sealing-tool upper part 3 includes on the lower surface thereof a silicone gasket 12, wherein silicone gasket 12 supports the pinching or compression of the film web 2 between the sealing-tool upper part 3 and the sealing-tool lower part 6 and seals the sealing-tool upper part 3 and the sealing-tool lower part 6 relative to one another to define an evacuatable chamber.

The tray holder 7 includes a cutting channel 13 above each reception area 10. This cutting channel 13 is defined in that the reception area 10, which is able to carry the tray edge 9, exhibits an offset V of at least five millimeters (5 mm), preferably between six millimeters (6 mm) and ten millimeters (10 mm), relative to a support surface (or bearing surface) 13a of the tray holder 7. The support surface 13a is defined in that the film web 2, i.e. the top film 2, rests thereon, when the sealing device 1 is closed. This explanation shows clearly that the cutting channel 13 according to the present invention is, contrary to the prior art, not a groove that externally surrounds the tray 8, but the cutting channel is here a recess in the tray holder 7 into which the tray is lowered until it rests on the reception area 10. The offset V guarantees that, even when a tray 8 has been placed into the tray holder 7, a sufficient amount of space is left above this tray for defining an evacuation gap having a dimension of one millimeter (1 mm) to two millimeters (2 mm), and that, in addition, the cutting knives 4, which normally have serrated cutting edges, will also be able to cut a downwardly yielding film web 2 without any risk of penetrating into the material of the tray 8 and damaging the tray 8. With an offset of at least five millimeters (5 mm) a very high process reliability can be accomplished, even if and in particular if the materials of the tray 8 and/or the film web 2 used are comparatively thick and cannot be handled easily.

While in use, the sealing device 1 is operable to seal one or more trays 8 in the following manner At the outset of each operating cycle, the sealing device 1 is open and trays 8 filled with the product in question are placed into the tray holder 7. The film web 2 is transported far enough in the direction of production P of the tray sealer for its residual film grid 14 to be located outside the sealing device 1 or at least outside the areas of the cutting knives 4.

Subsequently, the sealing device 1 is closed, as shown in FIG. 2. In the course of this process, the sealing-tool lower part 6 is lifted and pinches in its upper position the film web 2 together with the sealing-tool upper part 3. The space between the tray 8 and the film web 2 can now be evacuated and/or an exchange of atmosphere can be executed by means of gas flushing.

FIG. 3 shows the subsequent method step, during which the cutting knives 4 move downwards and dip into (inserted into) the respective cutting channel 13 of the tray holder 7 and, in so doing, cut a respective film lid 15 out of the film web 2, the film lids 15 being intended to be used as lids for the trays 8. The cutting knives 4 are laterally spaced 21 from the edge of the cutting channel 13 and dip into (inserted into) the cutting channel 13 only down to the level of the upper edge 16 of the trays 8. The cut-out film lids 15 are now located inside the cutting knives 4 at a small distance 17 from the tray edge 9 onto which they are to be sealed.

Subsequently, the sealing plate 5 is moved downwards, as shown in FIG. 4, and, in so doing, it carries along the cut-out film lids 15. At its lower position, which corresponds to its operating position, the heated sealing plate 5 presses the cut-out film lids 15 onto the tray edge 9 and the cut film 15 is sealed onto the tray 8 along a circumferentially extending sealing seam 19 (best seen in FIG. 5). The sealing itself depends on the temperature of the sealing plate 5, the pressure which the sealing plate 5 applies to the trays, and the time for which the sealing plate 5 is at the operating position. Subsequent to the sealing process, the sealing plate 5 and cutting knives 4 move upwards relative to the sealing-tool upper part 3, and the sealing-tool lower part 6 moves downwards carrying along the sealed trays 8 and, in so doing, opens the sealing device 1, as shown in FIG. 1.

The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.

Claims

1. A sealing device for a tray sealer for sealing a tray with a film lid made from a film web, the sealing device comprising:

a sealing-tool lower part and a sealing-tool upper part,

the sealing-tool lower part including a tray holder,

the sealing-tool upper part including a sealing plate and a cutting knife,

wherein the tray holder includes a support surface for the film web and a reception area as a support for an edge of a tray to be sealed, the reception area being offset relative to the support surface by at least five millimeters (5 mm) in a direction away from the sealing-tool upper part, so that the tray holder has integrated therein a cutting channel into which the cutting knife can be inserted for cutting a film web.

2. The sealing device according to claim 1, wherein the cutting channel is substantially arranged concentrically with the reception area of the tray holder.

3. The sealing device according to claim 1, wherein the cutting channel is substantially congruent with the reception area of the tray holder.

4. The sealing device according to claim 1, wherein a lateral distance of around three-tenths-of-one millimeter (0.3 mm) to three millimeters (3 mm) is provided between the cutting knife and an edge of the cutting channel.

5. The sealing device according to claim 1, wherein the cutting channel is arranged above the reception area for an edge of a tray to be held.

6. The sealing device according to claim 1, wherein a dimension of the cutting channel corresponds to an external dimension of a tray.

7. The sealing device according to claim 1, wherein the tray holder includes a plurality of cutting channels.

8. The sealing device according to claim 1, wherein the offset of the reception area relative to the support surface is at least six millimeters (6 mm) in a direction away from the sealing-tool upper part.

9. The sealing device according to claim 1, wherein the offset of the reception area relative to the support surface is between around seven millimeters (7 mm) to around ten millimeters (10 mm) in a direction away from the sealing-tool upper part.

10. A method of sealing a tray in a sealing device comprising:

inserting a cutting knife into a cutting channel of a tray holder of a sealing device;

cutting a film lid out of a film web with the cutting knife; and

sealing the film lid onto a tray after cutting the film lid.

11. The method according to claim 10 further comprising clamping the film web between a sealing-tool upper part of the sealing device and a support surface of the tray holder of the sealing device prior to cutting the film web.

12. The method according to claim 10 further comprising maintaining the cutting knife above a sealing plane while cutting the film lid from the film web.

13. The method according to claim 10 further comprising moving a sealing plate of the sealing device towards the tray holder, holding the cut film lid with the sealing plate, and compressing the cut film lid onto a tray in the tray holder to seal the cut film lid onto the tray wherein said cut film lid is located in a sealing plane.