TRAY SEALER AND METHOD

Abstract

A tray sealer and related method for sealing trays with a lid film wherein the trays may comprise several sealing planes that may be inclined with respect to each other. The tray sealer may include a tray seat and an upper sealing part operably disposed therein. The tray seat may comprise a circumferential tray edge support for supporting a tray edge of a tray. The upper sealing tool part may comprise a cutting facility and a circumferential sealing member for sealing a lid film onto the tray edge along a sealed seam. The tray edge support may include at least one first region with a first support plane and a second region with a second support plane. The first and second support planes may be orientated at an incline relative to each other.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to European Patent Application Number 13161314.3 filed Mar. 27, 2013, to Andreas Mader entitled “Tray Sealer and Method,” currently pending, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a tray sealer for a product tray and a method for operating the tray sealer.

BACKGROUND OF THE INVENTION

Tray sealers that seal trays with a lid film are known, for example, from EP 1 935 789 A1. Here, the trays have a tray edge with the sealing surfaces lying in a common plane and being oriented in parallel to the tray seat, an upper sealing tool part and a film plane of the lid film within the sealing tool.

SUMMARY OF THE INVENTION

It is the object of the present invention to expand the functionality of a tray sealer. A tray sealer according to the invention may comprise a tray seat and an upper sealing tool part. The tray seat may comprise a circumferential tray edge support for supporting a tray edge of a tray. The upper sealing tool part may comprise a cutting facility and a circumferential sealing member for sealing a lid film onto the tray edge along a sealed seam. The tray sealer may be characterized in that the tray edge support may comprise at least one first region with a first support plane and one second region with a second support plane, the first and second support planes comprising an inclination with respect to each other. This involves the advantage that particularly attractive and noticeable packages may be produced which has a three-dimensional sealing (i.e. a sealing different from a pure two-dimensional plane). With such a tray sealer according to the present invention, very diverse trays that include a sealed seam that is not lying only in one single plane may be sealed with a lid film even under vacuum or by gas treatment under a modified atmosphere.

Also included in the term “inclination of the support planes” are smooth transitions, such as concave or convex curvatures of the support plane, as here, the tangent lines comprise an inclination with respect to each other at different positions of such an extension of the support plane.

A circumferential tray edge support or a circumferential sealing member may also include interrupted, discontinuous surfaces.

The sealing member may preferably comprise a sealing area with at least one first region having a first sealing area and a second region having a second sealing area, the first and second sealing areas may comprise an inclination with respect to each other. Thus, a uniform sealing pressure necessary for a hermetic sealed seam may be applied onto the circumferential sealed seam.

Preferably, the circumferential tray edge support and the circumferential sealing member may be congruent with respect to each other.

The cutting facility may preferably comprise a circumferential cutting knife to cut the lid film out of a film web before it is sealed onto the tray edge of the tray. The knife edge may have an extension congruent to the tray edge or a knife edge lying in only one plane which is oriented in parallel to the upper sealing tool part and the tray seat.

In a particularly advantageous embodiment, the cutting knife may have a lateral distance with respect to the sealing member which is designed depending on the inclination of the sealing areas. If X designates the angle of inclination and L the length of a section of a tray edge extending at the angle of inclination X relative to the horizontal line, the lateral distance Z may be in particular selected to be Z=L (1−Cos(X)).

Preferably, the cutting knife may have a projection of at least 1 mm over the sealing areas of the sealing member, so that the lid film may be separated from the film web, while the film web is being clamped, by the upper sealing tool part and the tray seat and the sealing member may approach, together with the cutting knife, the tray edge support using a relative movement of the sealing member with respect to the upper sealing tool part.

In an advantageous alternative embodiment, the cutting knife may have a constant projection over the sealing area of the sealing member.

The method according to the invention for operating the present tray sealer for sealing a lid film onto a three-dimensionally shaped tray edge of a tray may comprise one or more of the following steps: (1) inserting a tray into a tray seat, the tray edge being supported by the tray seat along a tray edge support, the tray edge support being embodied to be congruent to the tray edge, (2) moving the tray seat and an upper sealing tool part toward each other, i.e. performing a closing movement during which the tray seat is moving, supported by one or several corresponding drives, towards the upper sealing tool part and/or the upper sealing tool part is moving towards the tray seat, (3) clamping a film web between the tray seat and the upper sealing tool part, (4) cutting a lid film out of the film web by means of the cutting facility during the moving step, (5) resting of the lid film on the tray edge only in sections, (6) folding the remaining lid film which is not yet resting on the tray edge to the tray edge by means of a sealing member of the upper sealing tool part during the moving step, (7) complete resting of the lid film on the tray edge, and/or (8) clamping and sealing the lid film onto the tray edge by means of a sealing area of the sealing member.

The step of folding the lid film may lead to each section of the tray edge being covered with the lid film at the end of this step.

This method may have the advantage that trays with a three-dimensional tray edge (i.e. a tray edge not only located in a two-dimensional plane) may be sealed with a lid film. In addition, in the process, the cutting of the lid film may be performed in a dimension which, during the sealed onto the tray edge, may be congruent to the dimensions of the tray edge support or the sealing member and thus the sealed seam produces a lid film that does not or only slightly projects beyond the sealed seam. This configuration may lead to a particularly attractive sealed package.

Preferably, the lid film may be completely cut out at first contact of the cutting facility with the film web to permit a stress-free clamping of the lid film on the tray edge. The wording “completely cut out” means that the lid film is cut out of the film web before the lid film as a whole is resting on the tray edge.

In a particularly advantageous embodiment, a cut edge of the lid film may be located such that the cut edge has a constant distance to a sealed seam after the lid film has been folded, clamped and sealed. This may also permit for a particularly attractive package.

In the present invention, it is conceivable to produce the sealed seam on a tray edge which is inclined, for example to the outside, relatively to the horizontal line and/or relatively to a plane spanned by the opening of the tray.

Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

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

FIG. 1 is a perspective view of one embodiment of a tray having a three-dimensional tray edge that may be sealed in a tray sealer in accordance with the teachings of the present invention;

FIG. 2 is a perspective view of one embodiment of a tray sealer in accordance with the teachings of the present invention;

FIG. 3 is a perspective view of a tray seat and a upper sealing tool part of one embodiment of the tray sealer of FIG. 2 cut along the line 3-3, and wherein the tray seat and the upper sealing tool part are in an opened position;

FIG. 4 is a sectional side view of the tray seat and the upper sealing tool part of FIG. 3 in an opened position;

FIG. 5 is a sectional side view of the tray seat and the upper sealing tool part of FIG. 3 while the lid film is being clamped;

FIG. 6 is a sectional side view of the tray seat and the upper sealing tool part of FIG. 3 while the lid film is being cut;

FIG. 7 is a sectional side view of the tray seat and the upper sealing tool part of FIG. 3 during sealing; and

FIG. 8. is a blown-up sectional side view of a tray edge of a tray in the tray seat and the upper sealing tool part shown in FIG. 7 during sealing.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the present invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the present 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 spirit and scope of the present invention. The present invention is defined by the appended claims and, therefore, the description is 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 tray 1 that may be sealed with the tray sealer of the present invention. One embodiment of tray 1 may be divided into three partitions 2 which may be filled, for example, with three different products. The tray 1 has a circumferential tray edge 3, where the tray edge 3 may be divided into three areas 3a, 3b, 3c. The three areas 3a, 3b, 3c of the tray edge 3 define three different sealing planes and each has an inclination X with respect to each other, so that a three-dimensional tray edge 3 or a three-dimensional sealing is present. For example, the sealing plane 3b is oriented horizontally, and the two sealing planes 3a and 3b arranged laterally of it are inclined downwards to the outside. This leads to the left area 3d of the sealing plane 3a and the right area 3e of the sealing plane 3c being situated underneath or lower with respect to the tray edge 3 of the sealing plane 3b. For comparison: Conventional trays for packing preferably food only have a two-dimensional sealing edge, so that a two-dimensional sealing plane exists.

FIG. 2 shows one embodiment of a tray sealer 10 of the present invention for receiving a tray 1 in a tray seat 11 provided in a movable drawer 12. The tray sealer 10 comprises a mounting 13 for a film web 14a (see FIG. 4), the film web 14a being pulled, together with the drawer 12, under an upper sealing tool part 16 provided behind a covering 15 and unwound from the mounting 13. A control system 17 controls the individual steps of the packaging process, wherein a lid film 14 is cut out of the film web 14a and sealed onto the tray 1, with one embodiment including lid film 14 being sealed onto the tray 1 after the interior of the tray 1 has been evacuated and/or treated with gas to produce a modified atmosphere within the package, so that maximum durability may be achieved.

FIG. 3 shows a perspective view of a section through the tray seat 11 and the upper sealing tool part 16. The tray seat 11 comprises a circumferential tray edge support 18 which supports the tray edge 3 of the tray 1 (shown in FIG. 1). The tray seat 11 comprises a circumferential seal 19 to be able to air-tightly clamp the film web 14a (see FIG. 4 for a better representation) between the tray seat 11 and the upper sealing tool part 16. On two sides each, the tray edge support 18 has a first region with a first support plane 18a, a second region with a second support plane 18b, and a third region with a third support plane 18c. The first support plane 18a has an inclination with respect to the second support plane 18b, and the second support plane 18b has an inclination with respect to the third support plane 18c. The first support plane 18a is oriented in parallel to the third support plane 18c, but the two support planes 18a, 18c are vertically offset with respect to each other.

The upper sealing tool part 16 comprises a cutting facility 20 in the form of a circumferential cutting knife 21 with a jagging and a circumferential sealing member 22 whose sealing area 23 has an extension congruent with respect to the tray edge support 18 and the regions 18a, b, c as well as the tray edge 3. The upper sealing tool part 16 moreover comprises a product protection plate 24 which protects products located in the tray 1 from the thermal radiation of the upper sealing tool part 16 and the sealing member 22, because the upper sealing tool part 16 is heatable to be able to supply heat via the sealing member 22 for sealing the lid film 14 and the tray edge 3, so that an air-tight sealed seam may be produced. The upper sealing tool part 16 moreover comprises a clamping plate 25 to clamp the film web 14a between the tray seat 11 and the upper sealing tool part 16 along the seal 19. The sealing member 22 and the cutting facility 20 are designed to be movable relatively to the clamping plate 25 via guides 26.

FIG. 4 shows a sectional view of the tray seat 11 with the tray 1 and the upper sealing tool part 16 and the film web 14a wherein tray seat 11 and upper sealing tool part 16 are positioned in an opened position after the tray seat 11 has been brought under the upper sealing tool part 16 together with the film web 14a by the drawer 12. As shown, the film web 14a is not yet in contact with the tray 1 or the horizontal sealing plane 3b located at the top. The sealing member 22 has a sealing area 23 with at least one first region with a first sealing area 23a and a second region with a second sealing area 23b, the first and the second sealing areas 23a, 23b comprising an inclination Y with respect to each other. The cutting knife 21 has a horizontal lateral distance Z with respect to the sealing member 22 which is embodied depending on the inclination Y of the sealing areas 23a, 23b. The cutting knife 21 has a vertical projection U of at least 1 mm with respect to the sealing area 23 of the sealing member 22. The sealing area 23 relates to the complete circumferential extension of the sealing area 23 itself, while the first and second sealing areas 23a, 23b only relate to certain partial areas or portions of the sealing area 23.

In FIG. 5, the upper sealing tool part 16 has been moved downward relative to tray seat 11 to such an extent that the clamping plate 25 air-tightly clamps the film web 14a against the seal 19.

In FIG. 6, the cutting of the film web 14a is shown, wherein the upper sealing tool part 16 with the cutting facility 20 has been moved downwards to the tray seat 11. In the process, the cutting facility 20 presses the film web 14a downward with the jagged cutting edge of the cutting knife 21, where the film web 14a only rests upon a portion of the tray edge 3 disposed centrically at the top, respectively the horizontal sealing plane 3b located at the top, and the film web 14a is tensioned by this configuration. In one embodiment, if this tension corresponds to the cutting power, then the cutting facility 20 cuts the lid film 14 out of the film web 14a along the cutting edge of the circumferential cutting knife 21 such that the lid film 14 is cut out of the film web 14a before the lid film 14 completely rests on the tray edge 3. During the cutting process, the lid film 14 obtains a cut edge 40.

The now cut out lid film 14 rests on a part of the tray edge 3 and is held by friction while the further movement of the sealing member 22 moves the part of the lid film 14 not yet resting on the tray 1 further towards the tray edge 3 with its sealing area 23. As shown in FIG. 7, at the end of the movement of the upper sealing tool part 16, the sealing member 22 presses the outer part of the lid film 14 against the tray edge 3 with its sealing area 23 and further against the tray edge support 18. By the mutual three-dimensional congruent shape of the sealing area 23, the tray edge 3 and the tray edge support 14, the production of a uniform circumferential sealed seam 30 by means of pressure and temperature applied for a certain period by the upper sealing tool part 16 is provided to produce a hermetically sealed package.

With reference to FIG. 7, it is also illustrated that the cutting facility 20 may be designed such that the lid film 14 is cut out of the film web 14a further outside on the right and left sides shown in the drawing, so that, after the resting of the lid film 14 upon the tray edge 3, the cut edge 40 does not project further beyond the produced sealed seam 30 than on the sides situated in the plane of projection in the front and rear. Thus, as best shown in FIG. 8, a constant distance A between the cut edge 40 and the outer edge of the tray edge 3 may be produced.

FIG. 8 also shows the tray edge 3 and the cut edge 40 of the lid film 14 and the cutting knife 21. Between the tray edge support 18 and the tray edge 3, a T-shaped silicone seal 41 may be provided. The sealed seam 30 is produced by the sealing area 23 of the sealing member 22 in connection with the T-shaped silicone seal 41 on the opposite side of the tray edge 3. The cut edge 40 of the lid film 14 has a distance A from the sealed seam 30. The distance A is preferably constant at the circumference along the sealed seam 30.

In the tray sealer 10 according to the invention, the supply of the film web 14a may be accomplished both longitudinally, as is shown, and transversely to the direction of transport of the tray 1. Tray sealers 10 which simultaneously seal several trays 1 in one cycle are also included in the invention. These tray sealers may be designed with multiple tracks and/or rows, multiple tracks meaning adjacent trays one next to the other, and multiple rows meaning adjacent trays one behind the other in a production direction each in one cycle.

As is evident from the foregoing description, certain aspects of the present invention are not limited to the particular details of the examples illustrated herein. It is therefore contemplated that other modifications and applications using other similar or related features or techniques will occur to those skilled in the art. It is accordingly intended that all such modifications, variations, and other uses and applications which do not depart from the spirit and scope of the present invention are deemed to be covered by the present invention.

Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosures, and the appended claims.

Claims

1. A tray sealer comprising: a tray seat comprising a circumferential tray edge support for supporting a tray edge of a tray; andan upper sealing tool part comprising a cutting facility and a circumferential sealing member for sealing a lid film onto the tray edge along a sealed seam;wherein the tray edge support comprises at least one first region with a first support plane and a second region with a second support plane, the first and second support planes being disposed in at an inclination with respect to each other.

2. The tray sealer according to claim 1, wherein the sealing member comprises a sealing area with at least one first region with a first sealing area and a second region with a second sealing area, the first and second sealing areas being disposed in at an inclination with respect to each other.

3. The tray sealer according to claim 1, wherein the circumferential tray edge support and the circumferential sealing member are congruent with respect to each other.

4. The tray sealer according to claim 1, wherein the cutting facility comprises a circumferential cutting knife.

5. The tray sealer according to claim 4, wherein the cutting knife has a lateral distance with respect to the sealing member, the lateral distance being related to the inclination of the sealing areas.

6. The tray sealer according to claim 4, wherein the cutting knife comprises a projection with respect to the sealing area of the sealing member of at least 1 mm.

7. The tray sealer according to claim 4, wherein the cutting knife comprises a constant projection with respect to the sealing areas of the sealing member.

8. Method for operating a tray sealer for sealing a lid film onto a three-dimensionally shaped tray edge of a tray, the method comprising: inserting a tray into a tray seat, the tray edge being supported by the tray seat along a tray edge support, the tray edge support being congruent relative to the tray edge;moving the tray seat and an upper sealing tool part toward each other;clamping a film web between the tray seat and the upper sealing tool part;cutting a lid film out of the film web using a cutting facility of the upper sealing tool part during the moving step;resting a portion of the lid film on a portion of the tray edge;folding another portion of the lid film not yet resting on a portion of the tray edge to the tray edge using a sealing member of the upper sealing tool part during the moving step; andclamping and sealing the lid film onto the tray edge using a sealing area of the sealing member.

9. The method according to claim 8, wherein the lid film is completely cut at first contact of the cutting facility with the film web.

10. The method according to claim 8, wherein a cut edge of the lid film is produced such that the cut edge has a constant distance with respect to a sealed seam after the folding, sealing and clamping of said lid film.

11. The method according to claim 8, wherein a sealed seam is produced on a section of the tray edge, said section of the tray edge being inclined with respect to the horizontal line or with respect to a substantially horizontally orientated sealing plane of the tray.