EP2960165B1 - Deep drawing packaging machine and method - Google Patents

Description

The invention relates to a thermoforming packaging machine according to the features of claim 1 and to a method according to the features of claim 7.

From the DE 102 37 933 A1 For example, a tray sealing machine is known for making skin packs having product overhanging a tray edge. The skin film is clamped on the sealing tool upper part and pulled into a dome, before the sealing tool base is moved with the shell and the product to the sealing tool shell. The skin film comes into contact with the product only during the skin process.

The EP 2 412 643 A1 shows a thermoforming packaging machine with a Oberfolienformstation to close a projecting vertically above a shell edge product with a shrink film and a trough, without that before the sealing process, the product itself deforms the shrink film by moving it upwards. The upper film forming station located upstream of the sealing station ensures a pre-deformation. In order to laterally guide the deformed shrink film during transport from the upper film forming station into the sealing station and to position it exactly on the recess, a clamp chain arranged on both sides is provided.

The WO 2004/000650 A1 shows a thermoforming packaging machine for producing a shrink wrap, wherein both the lower film and the upper film is a shrink film. The thermoforming packaging machine has a bottom film and a top film forming station in which the films are each deep drawn individually prior to sealing, so that a product to be packaged can be packed in the sealing station. The shrinkage effect of the films, in which they apply tightly to the product, is produced in a shrinking device following the thermoforming packaging machine by introducing heat, for example in a hot water bath. A difference between shrink wrapping and skin packaging lies in the fact that in shrink packaging the heat for the shrinking process is supplied only after the packaging process, and in skin packaging the heat is still present in the sealing film in the skin film the sealing process is introduced. A similar shrink wrap packaging machine is in the EP 2 412 643 A1 disclosed.

From the EP 0 270 208 A1 is known a thermoforming packaging machine for producing a skin pack. A skin film as a top film and a trough, which has been formed into a lower film and into which a product has been inserted, are transported together into a first forming station and clamped on all sides between a lower mold part and a mold upper part to subsequently vacuum-up the skin film into a dome pull and warm. This process leads to a slight deformation, so that after opening of mold lower part and upper mold part, the skin film during transport together with the trough and the product in a subsequent sealing station exerts no pressure on the product, as long as the product only slightly above the trough to the top survives. By the heat input, the skin film already has an elasticity, which is suitable to be pulled in the sealing station after forming a chamber through a sealing tool base and a sealing tool shell by means of vacuum in a dome, which has a significantly (4x) larger recess than the dome having in the mold shell. The skin film is then heated in the dome to an elevated temperature to then create by vacuum between the skin film and the trough a Skinpackung in which the skin film fits tightly against the product and on the inner surfaces of the trough and thus closes the product airtight. Increased deformation of the skin film in the forming station is not provided.

When sealing products overhanging the trough rim, there is a risk of wrinkling in the area of the clamping when closing the sealing tool lower part and the sealing tool upper part, which can later lead to errors in the seal or to leaks. In order to reduce or prevent such wrinkling, so far, the lateral distance of product is increased to the trough edge with increasing product supernatant. The resulting packages thus have a large trough surface with an upwardly projecting product. On the one hand, these packages are not appealing and, on the other hand, increased film consumption of the top and bottom film results, which in turn results in increased packaging costs and at the same time reduces the packaging performance of the thermoforming packaging machine, since fewer products can be processed during one working cycle. In thermoforming packaging machines with a multi-lane and multi-row format, the risk of wrinkling is even further increased.

The object of the present invention is to provide a thermoforming packaging machine which reduces the film consumption in the production of a skin package with products which have a product supernatant.

This object is achieved by a thermoforming packaging machine with the features of claim 1 or by a method for operating such a thermoforming packaging machine with the features of claim 7. Advantageous developments of the invention are specified in the subclaims.

The thermoforming packaging machine according to the invention comprises a bottom film forming station with a number of n mold cavities, where n is an integer greater than or equal to 2, for forming n cavities in a bottom film, and a top film forming station with n evacuable, each surrounded by a clamping surface Domen, the first Height between the clamping surface and a recess, for molding n lids in a top film, which is a skin film. In this case, the top film forming station is arranged upstream in a production direction in front of a sealing station, wherein the sealing station is configured to seal the lid with the associated n troughs, wherein the sealing station comprises a sealing tool top, which has n heatable and evacuatable dome with a second height. The domes are configured to abut the top film in the respective dome and to heat to a skin temperature. The first height is at least 80% of the second height.

Preforming the skin film in a top film forming station to the first height, which is at least 80% of the second height, provides pressure-free slipping of the covers over the product so that the distance between the product on the well and the well edge is less than 20 mm can be reduced, even if products with a product supernatant of more than 60mm are packed with a skin film. By reducing the dimensions of the wells, both the consumption of lower film and upper film can be reduced, as well as the machine performance can be increased because during a work cycle in the workstations more packaging can be processed. In addition, a Skinverpackung with little distance from product to Muldenrand more appealing than with a large distance. At the same time, the space required for such skin packaging in the refrigerated shelves or cabinets can be reduced.

Preferably, the second height is at least 60 mm, in a particularly advantageous embodiment at least 80 mm in order to be able to pack particularly large or over the trough edge upwardly projecting products.

Preferably, the skin temperature is at least 170 ° C to achieve an airtight surface seal between the skin sheet and the trough.

Preferably, an upper film transport device arranged on both sides of the upper film is provided in order to transport the covers from the upper film forming station into the sealing station. Thus, the cover can be positioned synchronously with the trough and the product as far as the sealing station, and transverse stresses in the skin foil itself do not lead to wrinkling due to the two-sided holding of the skin foil until jamming in the sealing station, which can lead to a lack of airtightness.

The mold cavities have a bowl depth and preferably the second height of the domes in the sealing tool upper part is at least 5 times, preferably at least 8 times, the cavity depth. This allows an attractive and volume-reduced skin packaging with a high product on a kind of plate, which is formed by the trough.

In a particularly advantageous embodiment, the n mold cavities in the bottom film forming station each have an opening length along and an opening width transversely to the production direction, and the n domes in the top film mold top each have a first opening length along and a first opening width transversely to the production direction, wherein the first opening length or The first opening width of the domes is between 80% and 95% of the opening length or the opening width of the mold cavity, respectively, in order that the molded covers, when fed into the sealing station, have larger dimensions than a product to be packaged. Due to the preforming of lids, the skin film can be quickly applied and heated by means of vacuum due to the small distance to the inner wall of the dome in the sealing tool shell and then to perform the skin process can. This shortens the cycle time of the sealing station and thus further increases overall packaging performance.

• gemeinsames Formen einer Anzahl von n Mulden, wobei n größer oder gleich 2 ist, in eine Unterfolie in einer Unterfolienformstation während eines Arbeitstaktes,
• gemeinsames Formen von n Deckeln in eine Oberfolie in einer Oberfolienformstation bei einer ersten Temperatur während eines Arbeitstaktes, wobei die Deckel anschließend eine erste Höhe gegenüber einer Oberfolientransportebene aufweisen,
• gemeinsames Zuführen der n Mulden und der n Deckel in eine Siegelstation,
• Anlegen der n Deckel an die Innenwand von Domen der Siegelstation mittels Vakuum zwischen den n Deckeln und den n Domen und Erwärmen der n Deckel auf eine zweite Temperatur, wobei die erste Höhe (D1) wenigstens 80% einer zweiten Höhe (D2) der Dome (18) der Siegelstation beträgt,
• Anlegen der n Deckel an die jeweiligen Produkte und die dazugehörigen Mulden mittels eines zwischen den n Deckeln und den n Mulden erzeugten Vakuums.

A method according to the invention for operating a thermoforming packaging machine for producing a skin pack which comprises a product projecting vertically above at least 50 mm vertically above a trough edge of a trough of a lower foil, wherein the upper foil is a skin foil, comprises the following steps:

• co-forming a number of n wells, where n is greater than or equal to 2, into a sub-foil in a sub-foil forming station during a work cycle,
• co-forming n covers into a top film in a top film forming station at a first temperature during a work cycle, the covers then having a first height from a top film transport plane,
• jointly feeding the n wells and the n lid into a sealing station,
• Apply the n cover to the inner wall of domes of the sealing station by means of vacuum between the n covers and the n domes and heating the n cover to a second temperature, wherein the first height (D1) is at least 80% of a second height (D2) of the dome ( 18) the sealing station is,
• Applying the covers to the respective products and the associated troughs by means of a vacuum created between the n lids and the n troughs.

Preferably, the lids are formed in the top film forming station such that the lids approach the associated troughs during transport from the top film forming station to the sealing station without exerting any pressure on the products of the associated troughs.

In this case, the upper film is preferably transported by means of an upper film transport device, for example two staple chains arranged on both sides of the upper film.

The first temperature to which the skin film is heated is preferably between 100 ° C and 140 ° C, to cause only a permanent deformation of the skin film to cover.

The second temperature to which the skin film is heated is preferably between 170 ° C and 220 ° C to produce the elasticity of the skin film for the subsequent skin process.

Fig. 1

eine erfindungsgemäße Tiefziehverpackungsmaschine in einer schematischen Seitenansicht,

Fig. 2a

eine schematische Seitenansicht einer Unterfolienformstation,

Fig. 2b

eine Draufsicht auf ein Formwerkzeugunterteil,

Fig. 3a

eine schematische Seitenansicht einer Oberfolienformstation,

Fig. 3b

eine Ansicht auf ein Oberfolienformwerkzeugoberteil,

Fig. 4a

eine schematische Seitenansicht einer Siegelstation in einer geschlossenen Stellung,

Fig. 4b

eine Untersicht auf ein Siegelwerkzeugoberteil,

Fig. 5

die Siegelstation von Fig. 4a nach Anlegen der Skinfolie im Dom und

Fig. 6

die Siegelstation von Fig. 4a nach Anlegen der Skinfolie an Produkt und Mulde.

In the following, an advantageous embodiment of the invention is explained in detail with reference to a drawing. In detail show:

Fig. 1

a thermoforming packaging machine according to the invention in a schematic side view,

Fig. 2a

a schematic side view of a bottom film forming station,

Fig. 2b

a plan view of a mold base,

Fig. 3a

a schematic side view of a top film forming station,

Fig. 3b

a view of a top film mold top,

Fig. 4a

a schematic side view of a sealing station in a closed position,

Fig. 4b

a subview of a seal tool shell,

Fig. 5

the sealing station of Fig. 4a after applying the skin film in the cathedral and

Fig. 6

the sealing station of Fig. 4a after applying the skin film to product and trough.

The same components are provided throughout the figures with the same reference numerals.

Fig. 1 1 shows a thermoforming packaging machine 1 according to the invention in a schematic side view and with a production direction R. In the production direction R, several workstations such as a bottom film forming station 2, a top film forming station 3, a sealing station 4, a cross cutting station 5 and a longitudinal cutting station 6 are provided in succession. In the following, the operation of the thermoforming packaging machine 1 according to the invention will be explained in more detail.

A lower film 7, which is designed for example as a plastic hard film, is unrolled from a first film roll 8 and detected on both sides by a staple chain, not shown, and transported into the lower film forming station 2. In the lower film forming station 2, the lower film 7 is heated and two troughs 9, which are arranged one behind the other and thus two-lane (i.e., side by side in the production direction R) with respect to the drawing plane, are formed in the lower film 7. Along an insertion path 10, which is arranged between the lower film forming station 2 and the sealing station 4, products 50 are placed in the wells 9, wherein the products 50 have a height of more than 50 mm.

A top film 11, which is designed as a skin film, is unwound from a second film roll 12 and transported by means of a two-sided upper film transport device 13 in the Oberfolienformstation 3 and heated there to a first temperature of about 120 ° C to two lids 14, the opposite to the plane of the drawing and thus arranged in two lanes, to shape. During the transport movement of the cover 14 by means of the upper film transporting device 13 towards the sealing station 4, the cover 14 are brought closer to the troughs 9 and to the lower film 4 and thereby slipped over the products 50, without exerting pressure on the products 50, since the Cover 14 have a size of the molding, which is greater than the dimension of the products 11.

The upper film transporting device 13, for example in the form of two staple chains 13 arranged on both sides of the upper film 11, assumes the function of accurately positioning the covers 14 over or onto the products 50 and is moved synchronously with the staple chain for the lower film 7. On the other hand, the upper film transporting device 13 takes over the function of the lateral holding of the skin film 11 or the cover 14 during the transport movement and within the sealing tool 4. Thus warping or wrinkling of the skin film 11 can be prevented by possibly occurring transverse stresses within the skin film 11 ,

In the sealing station 4, the lids 14 after forming a chamber 15 by a sealing tool upper part 16 and a sealing tool lower part 17 by means of a generated vacuum between the lids 14 and in the Fig. 3a formed domes 18 in the sealing tool upper part 16 to the inner wall of the dome 18 and heated to a skin temperature of, for example, 180 ° C, to have an appropriate for the subsequent skin process elasticity. At the same time, there is another vacuum inside the package 19, namely between lids 14 and troughs 9 created. By this vacuum and a venting of the sealing tool shell 16 to ambient pressure, the elastic cover 14 applies both tight to the product 11 and to the trough 9, wherein in this skin process, the skin film 11 and the cover 14 with the trough 9 a flat and produce airtight seal. This package 19 is referred to as a skin pack, since the product 11 located on or in the trough 9 is sealed airtight to the bottom foil 7 or the trough 9 with a foil 11 resting closely on the product 50, similar to a second skin.

In the further course in the production direction R, the two-lane next to each transported packages 19 are isolated by means of the cross-cutting station 5 and the longitudinal cutting station 6 and conveyed out of the thermoforming packaging machine 1 via a conveyor belt 20.

In the Fig. 2a the lower film forming station 2 is shown in more detail. It has a mold upper part 21 above the lower film 7, which is designed as a heating plate to heat the lower film 7 before molding to a temperature necessary for it. A movable in the arrow direction mold lower part 22 which is disposed below the lower film 7, has two mold cavities 23, in which the heated lower film 7 is formed by means of vacuum from below and / or compressed air from above into the mold cavity 23 to troughs 9. The trough 9 or the molding trough 23 has a trough depth T oriented perpendicular to the lower foil 7. The trough 9 itself also has a trough edge 25 after the molding process.

Fig. 2b shows the mold lower part 22 with the two mold cavities 23 in a plan view. The two mold cavities 23 each have an opening 24 upwards, which in turn have an opening length L extending parallel to the transport direction R and an opening width B extending transversely thereto.

Based on Fig. 3a the upper film forming station 3 will be explained in more detail. The top sheet forming station 3 comprises a top sheet die bottom 26 configured as a heating plate and an upper sheet forming die 27 having two domes 28 and a clamping surface 29 for clamping the skin sheet 11 between the top sheet forming die bottom 26 and the top sheet forming die top 27. The domes 28 have a first height D1, which passes through the planes of the clamping surface 29 and a recess 35 is defined with a maximum distance of an inner wall 30 of the domes 28. In a closed working position of the upper film forming station 3, the skin film 11 is clamped between the Oberfolienformwerkzeugunterteil 26 and the Oberfolienformwerkzeugoberteil 27, heated by the Oberfolienformwerkzeugunterteil 26 and pulled by vacuum into the dome 28. After opening the upper film forming station 3, a lid 14 is formed in the skin film 11.

Fig. 3b shows a sectional view AA, see Fig. 3 from below onto the clamping surface 29 of the upper film forming tool upper part 27. The two domes 28 each have an opening 28a, which in turn have an opening length L1 extending parallel to the transport direction R1 of the skin film and an opening width B1 extending transversely thereto. These dimensions largely correspond to the corresponding dimensions of the cover 14, since shrinkage effects can occur. The transport of the skin film 11 via an upper film transport device 13, in Fig. 3a shown as two mutually arranged staple chains 13.

Fig. 4 shows the sealing station 4 with closed sealing tool shell 16 and sealing tool base 17, the products 50 are enclosed by the lids 14 and the wells 9 and the lid 14 and the wells 9 circumferentially between the sealing tool upper part 16 and the sealing tool bottom 17 are clamped. In the chamber 15 thus formed, the covers 14 are sucked against the inner wall 32 of the mandrel 18 of the sealing tool upper part 16 via a vacuum V applied to the sealing tool upper part 16 and then bear against the inner wall 32. The sealing tool upper part 16 comprises a heater 33, by means of which the cover 14 are heated to the skin temperature.

Analogous to Fig. 3b the sealing tool upper part 16, like the upper film mold upper part 27, has two domes 18 with an opening length L2 extending parallel to the production direction R and an opening width B2 extending transversely thereto and a second height D2. This is shown in FIG. 4b In the bottom view of the dome 18. In this case 31 denotes the opening 18 of each dome 18. All three dimensions L2, B2 and D2 of the dome 18 of the sealing tool shell 16 are compared to the dimensions L1, B1 and D1 of the dome 28 of the upper film mold upper 27 by approx. 5% to 20% bigger. One of the reasons for this is that a distance A between two lids 14 following one another in the direction of transport R is advantageous, so that the sealing tool upper part 16 in its closed position, as in Fig. 4 can be moved, without causing a directly upstream of the sealing station 4 located cover 14 is too strongly influenced by a radiation heat of the sealing tool shell 16, even if in this position, the lid 14 is already largely over the product 50 is slipped.

Fig. 5 shows the phase in which the cover 14 abut in the domes 18 and by means of the heater 33 to a second temperature, ie the so-called. Skintemperatur, are heated, while the space between the wells 9 and the covers 14 is evacuated by means of vacuum V.

In Fig. 6 shows the situation after venting the sealing tool shell 16 and the application of the lid 14 and the skin film 11 to the product 50 and the trough. 9

Claims (11)

1. A thermoform packaging machine (1) comprising a bottom-film forming station (2) including a number n of mold cavities (23), n being larger than or equal to 2, for forming n troughs (9) into a bottom film (7), and a top-film forming station (3) including n evacuable domes (28), which are each enclosed by a clamping surface (29) and which have a first height (D1) between the clamping surface (29) and a hollow (35), for forming n lids (14) into a top film (11), which is a skin film, wherein the top-film forming station (3) is arranged upstream of a sealing station (4) in a production direction (R), wherein the sealing station (4) is configured for sealing the n lids (14) with the n troughs (9) associated therewith, wherein the sealing station (4) includes a sealing-tool upper part (16) comprising n heatable and evacuable domes (18) having a second height (D2), said domes (18) being configured for allowing the top film (11) to be brought into contact with the respective dome (18) from inside and for heating it to a skin temperature, and said first height (D1) amounting to at least 80% of the second height (D2).
2. The thermoform packaging machine according to claim 1, characterized in that the second height (D2) is at least 60 mm, preferably at least 80 mm.
3. The thermoform packaging machine according to one of the preceding claims, characterized in that the skin temperature is at least 170°C.
4. The thermoform packaging machine according to one of the preceding claims, characterized in that a top-film conveying unit (13) is provided, which is arranged on both sides of the top film (11), for conveying the lids (14) from the top-film forming station (3) into the sealing station (4).
5. The thermoform packaging machine according to one of the preceding claims, characterized in that the mold cavities (23) have a cavity depth (T), and that the second height (D2) of the domes (18) in the sealing-tool upper part (16) is at least 5 times, preferably at least 8 times as large as said cavity depth (T).
6. The thermoform packaging machine according to one of the preceding claims, characterized in that the n mold cavities (23) in the bottom-film forming station (2) each have an opening length (L) in the longitudinal direction of the production direction (R) and an opening width (B) in a direction transversely to said production direction (R), and that the n domes (28) in the top-film forming tool upper part (27) each have a first opening length (L1) in the longitudinal direction of the production direction (R) and a first opening width (B1) in a direction transversely to said production direction (R), the first opening length (L1) and the first opening width (B1) of the domes (28) amounting each to a value between 80% and 95% of the opening length (L) and opening width (B), respectively, of the mold cavity (23), so that the molded lids (14) will have dimensions that are larger than those of a product (50) to be packed, when they are supplied to the sealing station (4).
7. A method of operating a thermoform packaging machine (1) for producing a skin pack (19) including a product (50) that protrudes upwards, at least over 50 mm, vertically beyond a trough edge (25) of a trough (9) of a bottom film (7), the top film (11) being a skin film, said method comprising the following steps:

   - jointly forming a number of n troughs (9), n being larger than or equal to 2, into a bottom film (7) in a bottom-film forming station (2) during a work cycle,

   - jointly forming n lids (14) into a top film (11) in a top-film forming station (3) at a first temperature during a work cycle, said lids (14) having then a first height (D1) relative to a top-film conveying plane,

   - jointly supplying said n troughs (9) and said n lids (14) into a sealing station (4),

   - bringing the n lids (14) into contact with the inner wall (32) of domes (18) of the sealing station (4) by means of a vacuum between said n lids (14) and said n domes (18), and heating said n lids (14) to a second temperature, wherein the first height (D1) corresponds to at least 80% of a second height (D2) of the domes (18) of the sealing station (4),

   - applying the n lids (14) to the respective products (50) and the troughs (9) associated therewith by means of a vacuum generated between the n lids (14) and the n troughs (9).
8. The method according to claim 7, characterized in that the lids (14) are formed in the top-film forming station (3) such that the lids (14), while being conveyed from the top-film forming station (3) into the sealing station (4), approach the associated troughs (9) without applying any pressure to the products (50) of said associated troughs (9).
9. The method according to claim 8, characterized in that the top film (11) is conveyed by means of a top-film conveying unit (13), preferably by means of two clamp chains (13) arranged on both sides of the top film (11).
10. The method according to one of the claims 7 to 9, characterized in that the first temperature is a temperature between 100°C and 140°C.
11. The method according to one of the claims 7 to 10, characterized in that the second temperature is a temperature between 170°C and 220°C.

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