HK1260418B - Metallic can lid - Google Patents

Description

The present invention relates to a metallic can lid with a resealable opening, particularly for beverage cans and containers for the storage of foodstuffs and other liquid, paste, powder and/or solid products.

The plastic closure consists of a base part to be connected to the edge of the can opening, in which an opening is formed which is closed by a flat stop. The flat stop is connected to the opening stop by a plastic root joint so that the flat stop connected to a top-up barrel can be dissolved by applying a drag force over the top of the top-up barrel and dissolved in a substrate. The plastic base can be dissolved by applying a drag force over the top of the top-up barrel.

For example, retractable can lids are also described in DE 10 2010 013 531 A1 and EP 2 354 022 B1.

Finally, a resealable can lid is known from the applicant's DE 10 2015 112 428 A1 on which the present invention is based and which is to be substantially improved by the present invention.

The purpose of the invention is therefore to design the familiar retractable can lid in such a way that its manufacture is possible in an even more economical manner, the structural construction is simplified, material savings can be achieved and at the same time the function is improved.

This task is essentially accomplished by means of a metallic can cover with a metallic cover provided with a circular micro-slit and sealed inside the cover by a film with this adjacent inscription in the film, a plastic sealing frame connected to the fixed cover and enclosing the opening area, a plastic folding unit of non-metallic material connected to the metallic folding metallic cover area located inside the micro-slit, which is rotatably attached to the fixed cover area and is fitted with a folding structure facing the folding metallic cover area or diametrically opposite it, whereby the diametrical folding unit and the folding unit are connected to the fixed cover area and the corresponding folding metallic cover area and are connected to the underlying liquid-filled folding frame and are designed to be used in a process similar to that provided for in the cover area, in particular by means of a folding metallic ring and/or a folding metallic cover, and in particular by means of a liquid-filled folding unit and a liquid-filled folding unit which is connected to the folding metallic cover area and the corresponding liquid-filled folding underlying folding metallic cover and is designed to be used in a way which is more efficient and effective, in particular, by means of a forming and/or a forming of a device, in the cover area, in which the cover is designed, in particular, and/or the cover area, in which the cover, and the cover, in particular, the cover, in particular, the cover, the folding metallic cover, and/or the folding metallic cover area, and the folding metallic cover, in particular, in the cover, in the cover area, in which is designed to be used, in a more efficient and/or the cover, in the case of the cover, in particular, in the case of the cover, the cover, the cover, in the cover, in the case of the cover, the cover, in particular, the cover and the cover and the cover, and the cover, and the cover, and the cover, and the cover, in particular, in particular, in the case of the cover, and the cover, and the

The combination of the individual features of the can lid according to the invention makes it possible to accommodate and secure both the sealing frame and the closing unit in a space-saving manner and preferably in a depth of the can lid surface on the top of the can lid, thus avoiding the breakage of the can lid surface required in known designs. This also provides benefits in terms of hygiene, in particular in connection with the further specificity of the invention, which is that the closing unit has a safety gate extending to the fixed cover surface on its entire outer circumference, which is preferably connected to the fixed cover surface over the hatch cover.

This ensures that the plastic elements on the outside of the roof can not be penetrated by contaminants and the like.

The bottom of the metallic can lid, which is located inside the canister and consists of a virtually continuous metal surface containing only the micro-slot, is in turn connected through the adhesive layer to the plastic film mould securing the micro-slot, with the important point being that no plastic parts of the sealing unit or the seal frame extend through the metallic cover material and therefore only two components, the metallic lid on the one hand and the plastic mould on the other, have to come into contact and be connected.

It is also advantageous to use a preferable non-teethed or non-cut-off joint of the upward-sloping cover area, which is first protruded from the cover area and then pushed back into the cover area, taking advantage of the knowledge that the protrusion process can be designed in such a way that a conical expansion can be achieved in the cover material over a sub-area of the material thickness, which, by training the desired microslit, allows a form and/or force-seamless connection between the fixed cover area and the protruded cover area.

The solid compound may be in particular a plastic weld compound, where the adhesive coating serves as an adhesive between the plastic and the metal, or a so-called hot melt compound.

Preferably, the seal frame, closing unit and film form part are precisely aligned with respect to the metallic cover surface by means of preferably pointed positioning tips and associated, especially plunger-shaped, recesses.

Whereas the nozzles for the plastic parts positioned on the outside of the can lid are preferably formed on that plastic part, the nozzle-shaped recesses to accommodate the nozzles of the sealing frame on the bottom or inside of the lid act simultaneously as nozzles to position the plastic mould part, which has corresponding complementary recesses.

The finished can lid shall preferably consist of a composite material in the form of a sheet of sheet, in particular of aluminium or white sheet, coated on both sides with an adhesive and connected internally to the film component by means of the adhesive layer, whereby the mechanical strength of the film components in the composite material is appropriately chosen in such a way that, while ensuring the required overall strength of the composite material, the material strength of the metallic component can be reduced in comparison with a non-foil component, in particular by at least 1%.

In view of the huge number of can lids produced in practice, such a material saving, even if it is only 1%, for example, is already of comparative importance in economic terms and therefore represents a corresponding advantage.

Following a further development of the invention, the film-shaped part of the composite material extends to the edge of the edge intended for connecting the lid to a can and acts as a sealant and corrosion protection.

Since conventional cans in the area of the bolt-on connection usually require additional sealing material, the measure of the invention can again achieve practical savings and cost reductions.

The rotating bearing area, which is moulded to the closing unit, has a closed, bilaterally dilating, wedge-shaped, ironing area between its attachment area and the rotating part, which allows the closing unit to be positioned in a stable position. This arrangement ensures that the closing unit moves to an angle of more than 130° when an opening angle of about 90° is exceeded and is opened in this position, while when an angle of about 90° is exceeded from the opening angle the closing position is reduced to an opening angle of 30°. This operation can re-insert the closing position into the rearward opening angle.

The external training of this springboard is also important, as it avoids the gaps that are often present in conventional solutions and tend to pollute.

The design of the sealing frames and closing unit is of particular importance for the function of the reclosable can lid according to the invention. The sealing frames and closing unit work together via an inner sealing strip and an outer strap, which interfere in the corresponding receptacles.

The strap has a short slanted surface approach which interacts with a counter-stop of the associated recording equipment, providing a controllable play between the two interacting surfaces when the can is closed.

This small opening can be used to allow a reduction in excess pressure during the opening movement of the closing unit without the lid being so open at this stage that there is a risk of liquid leakage.

Another feature of the invention, which is important in order to reduce the cost of production of can lids, is that the can lid is at least substantially made of the same aluminium alloy as the container part attached to it and that the metallic material thickness of the can lid is essentially equal to the material thickness of the container part and preferably not exceeds at least twice the material thickness of the container part, the material thickness of the container part being in the range of about 0,1 mm and less.

Known cans, especially beverage cans, are made of aluminium alloys, where it is common to use an aluminium alloy 3000 series for the cylindrical can part and an aluminium alloy 5000 series for the lid part, to take account of the different technical requirements for the can part and the lid part. So far, only the wall thickness of the can wall has been reduced to about 0.09 mm by using aluminium alloy 3000 series, which is cheaper than the aluminium alloy 5000 series, which is usually used as a lid alloy. The wall thickness of the lid material must be at least twice the material thickness of the lids, but despite the known cover thickness, all the requirements for the thickness of the lids can be met to create a suitable thickness. These requirements can be met by using aluminium alloy 5000 series, which is typically used as a lid material.

In addition to the savings in production costs resulting from the choice of material or design of the composite material and the reduction in weight, it is essential that, also due to the special micro-slit design, it is no longer necessary to use a special material for the cover material, such as an aluminium alloy of the 5000 series, in particular 5182, since a low-cost aluminium of the 3000 series can now also be used for the metallic cover material.

Furthermore, the invention relates to a process according to claim 14 for producing a tight, tear-off or depressurable and preferably re-closable opening in a can lid, which is designed to be re-closed, where the opening area is either tear-off or can be pushed into the inside of the can.

Further details and advantages of the invention are given in the subclaims and explained in the following description of an embodiment by reference to the drawing.

The drawing shows: Fig. 1a side view of a can lid for a beverage can,Fig. 2a side view of the can lid as shown in Fig. 1,Fig. 3a cross section view as shown in line A-A in Fig. 1,Fig. 4an enlarged representation of detail B in Fig. 3,Fig. 5an enlarged representation of detail C in Fig. 3,Fig. 6an enlarged representation of detail D in Fig. 5 to explain the coupling mechanism between the sealing frames and the closing unit, andFig. 7a schematic representation of the perimeter of the barrier defining the opening area of the can lid.

The view shown in Figure 1 shows a lid 1 specially designed for a beverage can, with a retractable opening system integrated in the lid surface.

The lid has a lid area 10 which can be opened and swung upwards by means of a tear organ 17 as described in detail, via a swivel bearing area, the fixed part of which is attached to the lid. Between this fixed part 19 and a closing unit 11 which is firmly connected to the metal lid area 10, there is a swivel section 21 which allows the closing unit 11 to be opened to more than 130° if the opening angle of about 90° is exceeded, i.e. the closing unit can be moved back to its final opening position. This ensures that the slippage of the opening unit is reduced to a smaller angle of 90°. This operation can be carried out manually in both directions, and the opening unit can be moved to a smaller angle of 30°.

The cap 1 is preferably connected to the container by a rim 3.

The side view of the lid 1 shown in Figure 1 shows that the closing and opening system of the invention is so flat that it is completely absorbed into the depth of the lid part and no parts protrude from the lid contour in the closing position.

Figure 3 shows a section through the lid according to Figure 1 according to the A-A line, where the areas of detail which are particularly important for structure and function are marked with B and C, which are explained in detail below.

The figure D shows in greatly enlarged form the structural structure of a main component of the can lid in the form of a composite material.

This main component of the can lid consists of a suitably shaped sheet 5 of aluminium or white sheet, each of which is covered on both sides with an adhesive layer 7 acting as an adhesive medium, allowing a high-strength and durable bonding between metal, in particular aluminium, and the plastic, preferably polypropylene, of the film 6 provided on the bottom of the lid, i.e. the inside of the can, suitable for foodstuffs. The interconnection of the individual components of the composite material is preferably carried out in a so-called hot-sealing process, in which the plastic is melted to form a liquid bond with the metal.

Although the material strength of the metallic can lid can already be reduced by using the micro-split technology described above, unlike can lids with a tear-off line, the use of the can lid composite is advantageous because it allows the composite material to further reduce the material strength of the sheet metal without compromising the required strengths, thereby achieving significant material and cost savings in practice.

Figure 4 shows the area B of Figure 3 enlarged, i.e. the area where the retractor 17 is fixed to the upraised lid part, at its outer edge, so that when the lid part is lifted, the elasticity of the lid material in particular gives rise to a leverage effect which favors the opening of the lid part.

The plastic film 6 which is securely connected to sheet 5 by means of the adhesive layer 7 corresponds in its shape to the outline of the bottom of sheet 5 and preferably extends into the edge area 3 where it can act as a seal and corrosion resistant at the same time.

The disc cap material 5 has the invention of the flip-up cap area 10 as shown in Figure 1, which is bounded by a micro-slit 8 rather than a material attenuation as is the case in the present state of the art. This circular micro-slit 8 is preferably formed by protruding from the sheet metal of the cap area 10 and then being pushed back into the opening and held by clamping, so that a smooth metal surface is again present and the metallic cap with an adhesive coating on both sides can be handled as a single part.

Regardless of the specific method used to remove the flip-up cover area from the cover material, there is only a connection formed by a clamping device in the area of the micro-slit, so that no metal separation is required when a can with the cover of the invention is opened for the first time and thus the otherwise unavoidable formation of metallic micro-articles is excluded. This avoidance of the formation of micro-articles during the opening process, in particular aluminium micro-articles, is important from a health perspective, since such micro-articles inevitably enter the product contained in the can and thus also the human body.

The microspheres 8 preferably formed by a straight or curved and toothless line are covered and sealed by plastic film on the underside, i.e. the inside of the lid. The plastic film, preferably made of polypropylene suitable for food, has a notch 9 adjacent to the microspheres, which may be of equal or different depths in the surrounding area and ensures that only a relatively small force is required to open the lid. The distance between microspheres 8 and notch 9 is preferably about twice the thickness of the film, i.e. 3 to 4 tenths of a millimeter.

The required opening force depends not only on the force required to separate the bond between sheet 5 and plastic film 6 in the area of the microslit 8 but also on the sealing pairing achieved by the interaction of the sealing frame 14 and the closing unit 11.

The seal frame 14 of plastic material, in particular polypropylene, encloses the opening area and is securely connected to the metallic covering material by means of the adhesive layer 7 mentioned above, preferably in a sheet layer 5 recess, although it is possible to provide this solid connection only in the bottom area of the recess.

The sealing frame 14 has two receptacles 20, 15, 16 for a strap 12 and 13 for a strap 13, separated by a central sill, which are provided for the closing unit 11. These are also made of plastic material, preferably polypropylene.

This opening organ 17 connected to the outer edge of the closing unit 11 shall be fitted with a holding or fixing device 22 extending to the lid part and easily disengaged there, so that the integrity of the packaging concerned can be easily checked by means of this connection.

Diametrically opposite the opening organ 17 is a swing-bearing area 18 formed on the closing unit 11 in the shape of this frame, which is firmly connected to the cover surface outside the flip-up cover, as shown in Figure 5.

Figure 5 shows in enlarged form the detail area C shown in Figure 3, i.e. the swing-bearing area 18 diametrically opposite the opening organ 17 in conjunction with the sealing frames and closing unit 11 which, in the closed state of the canister lid, interact with each other in the manner shown and form a tight snap-rest joint.

The rib 13 included in the recording 16 and the rib 12 included in the recording 15 are functionally different, i.e. they have at least partially separate functions, which allow an optimisation of the interaction between sealing frames 14 and closing unit 11. The closing unit 11 is connected to the fixed part of the bearing via an integrated, tilting-able part 21. This holds the cover part consisting of the metallic cover area 10, the closing of the attached closing unit 11 and the lifting organ 17 back to more than 130° when the opening exceeds about 90°, so that the insulated container of the respective cap can be optimally accessed by 90°. The opening of the cover can be carried out at a small angle of 30° in both directions.

From the surface, the swing-bearing area 18 is a practically closed area, i.e. the gaps and openings commonly found in the tipper area in known solutions are avoided. Of particular importance from a hygienic point of view, however, the other feature of the invention is that the closing unit 11 is fitted with a sealing sheath 26 extending to the fixed cover area 2 on its entire outer circumference, which is preferably connected to the cover area 2 via the adhesive layer. This way it is ensured that no impurities, moisture and similar plastic elements can be released, i.e. a hygienic advantage is achieved which is not given by the first-order optical separation of this type of connection.

As can be seen in the further enlarged detail shown in Figure 6, the sealing strip 13 forms a sealing surface pair with the recording 16 23 This sealing surface pair 23 contributes to the snap operation during the closing process and keeps the closing unit in a defined position in the closed state.

However, by specifying the slope of the interacting sealing surfaces of the sealing surface pair 23 the opening resistance can also be adjusted, i.e. a slope sealing surface pair can be chosen to ensure that the internal pressure is withstood and that the opening process is not made too difficult.

The strap 12 and the attached inserts 15 also have short, interacting inclined surfaces which ensure the restraint, but also allow a small relative free movement in the form of a wedge 25 between the counter-rack 24 and the short inclined surface provided for in the strap 12 and this free movement can be used to allow a small initial opening movement when the can cap is opened repeatedly, which will reduce any internal pressure without the cap being opened to such an extent that any liquid could leak out in a disturbing way.

The diagram shown in Fig. 7 illustrates a preferred process of extrusion of the cover area 10 from sheet 5 and subsequent or subsequent reinsertion of the extruded area into the formed opening. The specially selected extrusion process, i.e. the specially selected stamping and matrix, results in the contour of the extruded area, viewed through its thicknesses, having a smooth cut and a slanted cut, which allow or facilitate the extruded sheet area to be pushed back into the extruded opening immediately or at a later date under the formation of a microstructure, and the area which is equipped with further processing of the clamp is kept in the extruded opening.

A particular advantage arises in the described stamping process when the sheet is coated with an adhesive coating with lubricant properties, since this eliminates any additional lubricants otherwise required in a stamping process, since the adhesive coating alone provides the required lubricant during the stamping process. This means that a food-grade lubricant is present, since the adhesive coats used according to the invention are food-grade and therefore no cumbersome cleaning steps are required, as would normally be the case in the case of an additional lubricant otherwise required.

Preferably, the stamping and matrix are chosen so that the resulting smooth cutting section covers less than 50% of the material thickness and the remaining slope section is essentially conical, thus achieving a sufficient force lock when the extruded part is inserted or pressed back into the sheet and no longer requiring special gears or cross-sections between the extruded part and the sheet to achieve the necessary holding forces.

In practical use, the re-sealable can lid according to the invention is also advantageous because the opening organ 17, preferably shaped as a ring-lock, is easily accessible, easily grasped and allows the can to be opened by a convenient pulling motion.

The can lid according to the invention is applicable to all types of containers which are intended to be resealable, the tight connection of the can lid to the respective container being possible not only by means of a rim, but also, especially in the case of non-metallic containers, by means of adhesive connections, welding connections and the like.

The invention also relates to a process for producing a tight, tear-resistant or compressible and preferably re-sealable opening in a flat sheet metal material, in particular a can lid, as described in detail in claims 14 to 18.

This manufacturing process, using a sheet metal layer preferably coated on both sides with a food grade adhesive, is suitable for the manufacture of can lids of the type described in the present invention as well as for the manufacture of standard can lids. In the case of such standard can lids, a two-arm lever is provided to open the respective opening area and is firmly connected to the cover material. The opening area is formed as a tongue-free slit separated from the cover area by a micro-slit extending over the load area, the slit being connected to the cover area at the base of the slit forming a significant opening area. The effective slit is so arranged that when the cover area is cut, the effective slit is limited by a microscopic line extending outside the load area, or by a plastic slit, the slit is made at the base of the load area.

If the arrangement is such that the tongue-tie is deflected outwards when opened together with the portion of the plastic coating which covers it below, bounded by the attenuation line, then the attenuation line is located within the microspheres.

The method of the invention may be designed in connection with retractable can lids of the type described so that the retractable lid is immediately pushed back into the sheet during retraction by spring force and is held in place, but it is also possible to separate the sheet on the one hand and the retractable lid on the other hand through further manufacturing steps in which they are connected to the plastic elements required to achieve the retractable opening and then to join the two components together and permanently connect them in the manner already described above, thus again obtaining the functionally retractable lid.

List of reference marks

1Dish cover2Fixed cover3Bördelrand4Composite material5Crust plating (Aluminium, white plate) 6Plastic foil, moulded part7Glue layer8Micro-split 9Cutting 10Swinging cover area11Wrapper unit12Restrain 13Stick-on 14Sealing frame15Inside cover area16Inside cover area17Removal organ18Swinging cover area19Fixed part of the swinging cover area, fastening material20Copper step21Kipper section22Fixing elements23Slag-on-dixity coupling24Grass 25Spiel 26Sealing belt

Claims (18)

1. A metallic can lid (1) having a reclosable opening, in particular for beverage cans and for containers for storing foods and other liquid, pasty, powdery and/or solid products; having a microgap (8) which extends peripherally, which is provided in the metallic lid surface and which is sealed off at an inner lid side by a film (6); having a notch (9) extending adjacent to said microgap (8) in the film; having a sealing frame (14) composed of a plastic material which is connected to the fixed lid surface (2) and which surrounds the opening region; having a closure unit (11) composed of a plastic material which is connected to the metallic lid region (10) which is disposed within the microgap (8) and which can be pivoted open, said closure unit (11) being pivotably attached to the fixed lid surface (2) and being provided with a tear-open member (17) disposed diametrically opposite the pivot bearing region (18), wherein the sealing frame (14) and the closure unit (11) cooperate via sealing and latching ribs (12, 13) and associated receiving grooves (15, 16) and the metallic lid region (10) disposed within the annular microgap (8) is received and held in the opening region of the lid, in particular in a shape matched and/or force transmitting manner and preferably without a toothed arrangement; and wherein the film (6) provided at the inner lid side and covering the microgap (8) consists of a molded part, in particular a deep-drawn molded part, which reproduces the lower side structure of the can lid forming a continuous metallic surface, characterized in that both the sealing frame (14) is connected to the fixed lid surface (2) in a bonded manner and the closure unit (11) is connected to the metallic lid region (10) that can be pivoted open in a bonded manner, in particular by a thermal process using an adhesive lacquer layer (7) which is preferably suitable for use with food and/or has lubricating properties.
2. A can lid in accordance with claim 1, characterized in that the sealing frame (14), the closure unit (11) and the molded film part (6) are exactly mutually aligned with respect to the metallic lid surface by means of positioning studs which are preferably point-shaped and associated recesses which are in particular cup-shaped.
3. A can lid in accordance with claim 1, characterized in that the can lid is formed by a composite material in the form of a sheet metal layer (5), in particular composed of aluminum or tin plate, which is coated at both sides by an adhesive lacquer (7) and which is connected at the inner side to the molded film part (6) via the adhesive lacquer layer (7); and in that the sealing frame (14), the closure unit (11) and the pivot bearing region (18) are permanently connected to the sheet metal layer (5) via the outwardly disposed adhesive lacquer layer (7), in particular by plastic welding or by a so-called hot melt connection.
4. A can lid in accordance with claim 3, characterized in that the mechanical strength of the film component in the composite material (4) is selected such that, while ensuring the required overall strength of the composite material, the material thickness of the metallic component can be reduced, in particular by at least 1 %, in comparison with a film-free component.
5. A can lid in accordance with one or more of the preceding claims, characterized in that the molded film part (6) of the composite material (4) extends up to and into the bead margin (3) which is provided for connecting the lid to a can and which acts there as a sealing material and as corrosion protection.
6. A can lid in accordance with one or more of the preceding claims, characterized in that the pivot bearing region (18) molded at the closure unit (11) has, between its fastening region (19) and the pivot part, a hoop region (21) which is closed at the outer side, which expands in a gusset-like manner at both sides, which acts as a tilt spring, which moves the closure unit (11) into an open position at an angle of more than 130° after an opening angle of approximately 90° has been exceeded and which moves the closure unit (11) to an opening angle of less than 30° on a falling below of an opening angle of approximately 90°, whereupon the closure unit can be pressed manually from this position into a sealed off closed position.
7. A can lid in accordance with one or more of the preceding claims, characterized in that the sealing frame (14) has inwardly and outwardly disposed receiving grooves (15, 16) which are each peripheral; and in that a peripheral sealing rib (13) is associated with the inwardly disposed groove (15) and a peripheral latching rib (12) is associated with the outwardly disposed groove (16) at the closure unit (11), with a sealing pairing (23) of slanted surfaces predefinable in their inclination being provided between the sealing rib (13) and a wall of the receiving groove (15) and the latching rib (12) having a predefinable clearance in an opening direction with respect to a counter-latch (24) in the receiving groove (16), and/or with a snap-in latching connection having haptic and/or acoustic feedback being formed.
8. A can lid in accordance with one or more of the preceding claims, characterized in that the notch (9) adjacent to the microgap (8) has a different thickness in its extent, with, for the purpose of reducing excess pressure in a can, the region of the film that is first acted on by the opening force in the opening process having a notch with a larger depth than an adjoining part region which is in particular short, which has a smaller depth and which is in turn followed by a notch region having a depth which is substantially equal to the notch depth in the initial region of the opening movement.
9. A can lid in accordance with claim 8, characterized in that the excess pressure reduction takes place during the opening movement of the closure unit (11) within the latching rib clearance (25).
10. A can lid in accordance with one or more of the preceding claims, characterized in that the metallic can lid at least substantially comprises the same aluminum alloy as the container part connected to it and an alloy of the "Aluminum 3000" series, in particular the 3104 alloy, is preferably used as the aluminum alloy.
11. A can lid in accordance with claim 10, characterized in that the material thickness of the can lid is substantially equal to the material thickness of the container part and preferably at least does not exceed twice the value of the material thickness of the container part, with the material thickness of the container part being in a range of approximately 0.1 mm and less.
12. A can lid in accordance with one or more of the preceding claims, characterized in that the closure unit (11) has at its outer periphery a sealing apron (26) which extends up to the fixed lid surface (2) and which is connected to the lid surface (2) in a bonded manner, preferably via the adhesive lacquer layer (7).
13. A can or a container composed of metal or plastic, characterized in that a hermetically sealed closure is produced by using a can lid in accordance with one or more of the preceding claims.
14. A method of manufacturing a sealed opening, which can be torn open or pressed in and can be reclosed, in a can lid in accordance with one or more of the preceding claims, wherein an areal region corresponding to the opening is punched out from the coated sheet metal material in such a manner that the punching die engaging at the coated side cooperates with a die which brings about a smooth cut region and an adjoining slanted cut region of the punched out part; the punched out areal region whose peripheral contour is substantially complementary to the die shape is again inserted into the opening in the sheet metal material and is held therein in a shape matched and/or force transmitting manner; and the microgap formed between the sheet metal material and the punched out areal region is covered at the one side by a film which is areally coated onto or laminated onto the sheet metal material and which is provided with a peripheral weakening or notch adjacent to the microgap, characterized in that the sheet metal material is coated at least at one side by an adhesive lacquer layer; and in that the lubricant required for the punching process is supplied exclusively and solely by the adhesive lacquer layer.
15. A method in accordance with claim 14, characterized in that the sheet metal material is provided with an adhesive lacquer layer suitable for use with food at both sides and in particular over the full area.
16. A method in accordance with claim 14 or claim 15, characterized in that a preshaped film adapted to the sheet metal layer shape is used as the film and this molded film part is joined to the sheet metal layer by means of the adhesive lacquer layer.
17. A method in accordance with claim 14, characterized in that the punched out areal region is fixed in the opening in a shape matched and/or force transmitting manner by means of a spring force on a return stroke of the punch plunger.
18. A method in accordance with claim 14, characterized in that the smooth cut region at the punched out areal region extends over less than 50% of the material thickness and the slanted cut region preferably expands conically.