EP1975076A1 - Tin can and a method for manufacturing the same - Google Patents

Abstract

The tin can has an axial welded joint, a central cylindrical section (4), and a conical opening section (8) sealable by a cover, which is made of foil material. A reinforcing seam (9) reinforces the conical opening section, and is formed in a circumferential direction between the opening section and the cylindrical section. The reinforcing seam protrudes inwardly to a longitudinal axis of the tin can, and has a radius of curvature between 1 millimeter and 3 millimeters. An independent claim is also included for a method for manufacturing a tin can.

Description

The present invention relates to a can with an axial weld, a central cylindrical portion and a sealable with a lid of a sheet material conical opening portion. The invention also relates to a method for producing such a tin can, comprising the steps of: bending a plate-shaped starting material to form a cylindrical sheet metal blank, longitudinal welding along the longitudinal sides of the sheet metal blank to form a cylindrical sheet metal blank with the axial weld and forming the opening portion of the welded sheet metal blank Shapes a conical opening section.

A cylindrical tin can having a support ring formed on the opening and carrying a peelable lid is well known. The support ring of this prior art can has a portion projecting from the inner peripheral surface of the can and extending perpendicular to the longitudinal axis of the can. This section forms a support surface for attaching the lid. The support ring is connected to the tin can at the upper end of the opening portion by crimping this end. Due to the Tragerings the emptying of the can is difficult. When tilting the can to empty the contents prevents the projecting portion of the support ring easy and consumer friendly emptying. Thus, depending on the flow properties of the material received in the can, the consumer sometimes has to reach in for emptying the can with his finger. This can lead to cuts due to the formed of a sheet metal support ring.

To solve the problems associated with this prior art prior art has been a tin can according to the preamble of claim 1 and a method for their preparation according to the preamble of claim 10 with the EP 0 700 838 B1 proposed. This generic prior art proposes to form the can having a central cylindrical portion, a conical opening portion, and a neck formed between the conical opening portion and the central cylindrical portion. The cylindrically shaped retraction connects at its front end to the conical opening portion of the generic box. On the inner circumferential surface of the conical opening portion, the lid is sealed to close the can. The upper end of the central cylindrical section connects via a tapered section at the lower end of the feeder.

Although the generic tin can simplifies emptying and avoids the risk of injury, the conical opening section tends to be deformed when the lid is removed. In particular, the conical opening portion is taken along by a conical edge portion of the lid until the applied by the consumer force to pull off the lid solves the connection between the conical opening portion and the conical edge portion. However, such a deformed conical opening section makes it difficult to controlled draining the tin can.

Starting from the generic state of the art, it is an object of the present invention to provide a tin can which allows a controlled and consumer-friendly emptying. Another object of the present invention is to provide a method of manufacturing such a can.

The device-related aspect of the present invention is achieved with a can according to claim 1, characterized by means for stiffening the conical opening section. The means may be formed, for example, by at least one stiffening element formed on the outer peripheral surface of the conical opening portion. For example, the means is mainly formed so as to prevent deformation of the tapered opening portion due to a tensile load acting on the tapered opening portion.

According to a preferred embodiment of the present invention, the means is formed in the circumferential direction between the conical opening portion and the central cylindrical portion in the form of a stiffening bead. The stiffening bead runs, for example, along the entire circumference of the tin can. The stiffening bead is formed, for example, as a stiffening bead projecting radially outwardly from the outer circumference of the tin can and projecting beyond the outer circumferential surface of the central cylindrical portion. The stiffening bead has, for example, a substantially triangular shape when viewed longitudinally, preferably with rounded edges or transitions.

According to a particularly preferred embodiment, the stiffening bead projects inwards towards the longitudinal axis of the tin can and has a radius of curvature of between 1 mm to 3 mm. The stiffening bead is thus formed according to this preferred embodiment as a projecting on the inner peripheral surface of the tin box radially inwardly curved stiffening bead. As a result, the problem underlying the invention is not only solved by a deformation of the conical Opening portion is effectively prevented, but also that the material to be emptied from the tin can not be retained due to the stiffening bead in the tin. Accordingly, there is no danger that, for example, powder stored in the tin box will be retained when emptying the tin can due to the stiffening bead. A controlled and consumer-friendly emptying is thus always possible.

According to a further preferred embodiment, the stiffening bead connects with its first end directly to the conical opening portion and with its second end directly to the central cylindrical portion. The stiffening bead is thus arranged directly in the vicinity of the conical opening portion, whereby a stiffening of the entire conical opening portion is achieved. This arrangement of the stiffening bead in close proximity to the conical opening portion and the central cylindrical portion also leads to a more compact construction of the tin.

Preferably, the transition from the first end to the conical opening portion and from the second end to the central cylindrical portion each have a radius of curvature of between 0.8 mm and 1.6 mm. The inner circumferential surface of the central cylindrical portion via the curved projecting stiffening bead toward the conical opening portion is thereby formed continuously, i. there is no kink or any other discontinuity along the inner peripheral surface of the can, which could retain the product stored in the can.

According to another preferred embodiment, the lid has a circular base and a conical edge portion, and the outer peripheral surface of the rim portion abuts completely with interposition of a thermoplastic sealing layer on the inner circumferential surface of the conical opening portion. The diameter of the circular base preferably corresponds substantially to the diameter of the central cylindrical portion and the lower end of the conical opening portion. The length of the conical edge portion preferably corresponds to the length of the conical opening portion. The preformed conical edge portion of the lid extends parallel to the conical inner peripheral surface of the opening portion. Completely within the meaning of the invention not only means that the length of the conical edge portion coincides with the length of the conical opening portion, so that the conical edge portion can fully abut the opening portion, but also that the conical edge portion smooth, ie free of air bubbles, along the entire inner peripheral surface the conical opening portion abuts. The thermoplastic sealant layer is preferably formed on the basis of polyethylene. This preferred Embodiment allows for optimal material usage and provides excellent hermetic sealing.

According to a particularly preferred embodiment, the conical edge portion and the conical opening portion are each offset by 8 ° to 12 ° relative to the longitudinal axis of the tin can to the outside. Since the angle between the edge portion and the longitudinal axis of the tin can and between the conical opening portion and the longitudinal axis of the tin can between 8 ° and 12 ° in longitudinal section of the tin can, a particularly good adhesion between the edge portion and the conical opening portion is achieved. Also, the insertion and attachment of the lid to the conical opening portion is favored by this angle.

According to a further preferred embodiment according to the present invention, for removing the cover from the conical opening portion a formed on the conical edge portion Abziehlasche is formed, which allows the removal of the lid. The pull tab is preferably from the outer edge of the conical edge portion. Since the can according to the present invention comprises means for stiffening the conical opening portion, the pull tab can thus be formed at the conical edge portion without having to fear deformation of the conical opening portion of the can when removing the lid. The means for stiffening the conical opening portion thus also has the advantage that the Abziehlasche instead of on the circular base of the lid, which covers the opening of the tin box, consumer-friendly can be formed directly on the conical edge portion of the lid.

According to a further preferred embodiment, the pull tab is formed integrally with the conical edge portion by cutting out the foil material and arched such that a first portion of the pull tab extends parallel to the conical edge portion and a second portion of the pull tab parallel to the circular base. Due to the one-piece design of lid and pull tab, the material is used optimally. Since the pull tab is arched so as to substantially follow the shape of the conical edge portion and the circular base, this also forms a preferred compact arrangement of the pull tab. The pull-tab is preferably arcuate such that the respective first and second portions abut the conical edge portion and the circular base. Only when opening the can, the pull tab is lifted by the consumer, before she takes one space-saving and compact position immediately adjacent; preferably adjacent to the top of the lid.

The procedural problem is solved according to the present invention by a method according to claim 10, which is characterized by molding a means for stiffening the conical opening portion. The conical opening portion is preferably deformed by being concreted to obtain the conical opening portion with a predetermined angle between the conical opening portion and the longitudinal axis of the can. The opening portion is preferably bent around in such a way that its front end projects beyond the lateral surface of the central cylindrical portion. By the conification, a conical opening portion is formed by reshaping, the diameter of which continuously increases toward its front end. The smallest diameter of the conical opening portion is thus formed at its lower end. The means for stiffening the conical opening portion is formed, for example, by attaching stiffening elements to the outer periphery of the tin can. The stiffening elements can be prepared as separate components and attached to the sheet metal blank or formed integrally on the sheet material of the sheet metal blank. Preferably, however, the means is formed by reshaping the sheet material of the can between the conical opening portion and the central cylindrical portion in the form of a stiffening bead. This stiffening bead is preferably formed completely along the circumference of the sheet metal blank. Preferably, the sheet metal blank is pressed inwardly between the conical opening portion and the central cylindrical portion inwardly toward the longitudinal axis of the sheet blank so that the stiffening bead is formed with a radius of curvature between 1 mm and 3 mm. By forming to form the stiffening bead not only prevents the conical opening portion deformed when removing the lid, but also that the conical opening portion in subsequent processing steps of the sheet metal blank, for example, when attaching the lid or filling the tin box, not deformed.

A particularly preferred embodiment of the present invention is characterized by cutting the lid with a peel tab from the film material and forming the lid to form a circular base and a conical edge portion, wherein at least the conical edge portion forming portion of the film material is coated with a thermoplastic sealant layer. The film material is preferably an aluminum foil from which the lid is cut out. In terms of resource optimization, the lid is cut in one piece with the pull tab. The cut-out lid is provided by a tool provided for this purpose deformed such that the conical edge portion is formed along the entire circumference of the circular base surface, wherein the Abziehlasche extends from a portion of the edge portion. The sealing layer is preferably formed by a polyethylene layer and is preferably applied along the entire inner peripheral surface of the conical edge portion. The lid is preferably reshaped such that the diameter of the circular base area substantially corresponds to the diameter at the lower end of the conical opening portion. The length of the conical edge portion preferably corresponds to the length of the conical opening portion. By preforming the lid, a precise balance between the conical opening portion and the conical edge portion can be achieved, whereby a reliable connection between the conical opening portion and the conical edge portion is ensured. The Abziehlasche is after the forming of the lid preferably from the edge of the conical edge portion, in its longitudinal extent from.

According to a preferred embodiment, the step of forming the lid comprises deep-drawing the cover to form the circular base and the conical edge portion such that the conical edge portion is formed smooth. The deep drawing is carried out with a conical tool, whereby the lid is formed reliably and dimensionally accurate. In particular, the lid is reshaped so that the conical edge portion is smooth or wrinkle-free, i. strictly corresponds to the outer peripheral surface of a truncated cone. The thus preformed lid ensures that the conical edge portion is applied under optimal conditions to the conical opening portion with the interposition of the sealing layer. The occurrence of air bubbles and thus the weakening of the seal to be produced is reliably prevented.

According to a particularly preferred embodiment of the present invention, the method is characterized by grasping the reshaped lid with a heatable die which heats the thermoplastic sealant layer upon transferring the formed lid to the welded blank, inserting the unshaped lid into the conical mouth portion of the welded blank, applying of the conical edge portion to the conical inner peripheral surface of the opening portion such that the conical edge portion with the interposition of the heated thermoplastic sealing layer completely applied to the conical inner peripheral surface and hermetically sealed, the conical opening portion of the welded sheet blank, whereby the sealed with the lid tin can. The unshaped lid is preferably sucked by vacuum on the stamp and transferred to the sheet metal blank. The stamp is preferably permanently heated to the thermoplastic Heat seal layer and melt. The lid with the heated sealing layer is then inserted into the conical opening portion, and the conical edge portion is applied to the inner peripheral surface of the conical opening portion with interposition of the heated thermoplastic sealing layer for hermetically sealing the opening. Specifically, the tapered edge portion is pressed by a predetermined force against the inner peripheral surface of the conical edge portion, to thereby obtain a uniform distribution of the sealing layer between the inner peripheral surface of the conical opening portion and the inner peripheral surface of the tapered edge portion.

Since the lid is already preformed with the smooth conical edge portion, the lid can be quickly and reliably inserted and applied. In particular, a stable and reliable seal is provided in a very short time by the combination of preforming of the edge portion to obtain a smooth, wrinkle-free edge portion and complete application of the smooth conical edge portion to the conical opening portion. Here, the stiffening bead contributes to the fact that the conical opening portion is not deformed during the processing of the sheet metal blank. It is therefore ensured that the preformed conical edge portion can be fully applied to the conical opening portion. A subsequent adjustment of the conical edge portion is not necessary. Compared to the EP 0 700 838 B1 is achieved by introducing the preformed with a conical edge portion lid a considerable time savings. In the generic state of the art, a hat-shaped lid must first be inserted so that its outer edge folds over and abuts against the inner peripheral surface of the conical opening portion. This is time consuming and involves the disadvantage that the lid can not be mounted precisely enough on the conical opening portion. Therefore, the generic method can not achieve complete abutment of the edge portion of the lid with the inner peripheral surface of the conical opening portion. There is thus the danger that the lid will come off the tin. In addition, in the generic method, the lid must first be inserted and applied to the inner peripheral surface of the tapered opening portion before the sealing layer can be heated. The productivity of this known method is therefore low. Further, wrinkles may form in the edge portion of the lid since it has not been preformed. There is in the generic state of the art also the risk that due to a lack of stiffening bead, the conical opening portion deformed during the completion of the tin. This increases the risk of having the edge portion of the lid is not fully applied to the inner peripheral surface of the conical opening portion.

According to a further preferred embodiment, the cover is inserted in such a way that the lower edge of the conical edge section is arranged in the region of the transition from the first end of the stiffening bead to the conical opening section. The lower edge of the conical edge portion of the lid is thus directly attached to the transition from the first end of the stiffening bead to the conical opening portion. The radially inwardly curved stiffening bead forms the smallest inner diameter of the tin can and prevents the lid from being fed in too far along the longitudinal axis of the tin can. The stiffener bead contributes to accurate and reliable positioning of the lid. This ensures that the conical edge portion of the lid rests completely and in a positionally accurate manner on the inner peripheral surface of the conical opening portion.

According to another preferred embodiment of the present invention, the stamper applies the conical edge portion to the colder inner peripheral surface of the opening portion and is removed before the sheet reaches the melting temperature of the sealing layer. By heating the sealing layer during transfer, it is ensured that the stamp reliably attaches the cover to the welded tin can. The lid is heated substantially only during transfer. Since the preheated conical edge portion of the lid is applied to the colder sheet, the lid is sealed directly onto the can.

According to a preferred embodiment, after the sealing, the pull tab formed on the conical edge portion is reshaped such that a first portion of the pull tab extends parallel to the conical edge portion and a second portion of the pull tab extends parallel to the circular base. Since the pull-tab is turned over only after the conical edge portion has been applied and then sealed, a uniform force distribution is ensured by the punch at the conical edge portion during application since the pull tab is not interposed between the punch and the outer peripheral surface of the conical edge portion. By bending the pull tab a particularly compact arrangement of the same is achieved.

According to a further preferred embodiment of the method according to the invention, the conical edge portion for positive attachment to the conical Opening portion by 8 ° to 12 ° relative to the longitudinal axis of the tin and the conical opening portion formed by 8 ° to 12 ° relative to the longitudinal axis of the tin can to the outside. By setting the angle between the conical opening portion and the longitudinal axis and the conical edge portion and the longitudinal axis to 8 ° to 12 ° excellent adhesion by sealing is achieved and further facilitates the insertion and attachment of the lid in the conical opening portion. These effects can be further increased by setting the angle to preferably 9 to 10 °.

Further preferred embodiments of the method according to the invention are specified in the subclaims.

Fig. 1

eine Längsschnittansicht eines Ausführungsbeispiels einer Blechdose;

Fig. 2

eine vergrößerte Ansicht eines konischen Öffnungsabschnitts der Blechdose nach Fig. 1;

Fig. 3

eine Längsschnittansicht eines Deckels der Blechdose nach Fig. 1;

Fig. 4A-4B

eine Verfahrensschritt zum Trennen eines Ausgangsmaterials gemäß einer Ausführungsform eines Verfahrens zum Herstellen eines Blechrohlings;

Fig. 4C

eine vergrößerte Detailansicht von Detail "C" gemäß Figur. 4B;

Fig. 4D

einen Verfahrensschritt zum Einziehen eines Bodenabschnitts des Blechrohlings nach Fig. 4B gemäß der Ausführungsform des Verfahrens;

Fig. 4E

eine vergrößerte Detailansicht von Detail "E" gemäß Figur. 4D;

Fig. 4F

einen Verfahrensschritt zum Bördeln des Bodenabschnitts nach Fig. 4D und eine oberen Abschnitts des Blechrohlings gemäß der Ausführungsform des Verfahrens;

Fig. 4G

eine vergrößerte Detailansicht von Detail "G" gemäß Figur. 4F;

Fig. 4H

eine vergrößerte Detailansicht von Detail "H" gemäß Figur. 4F;

Fig. 41

einen Verfahrensschritt zum Konifizieren eines Öffnungsabschnitts des Blechrohlings nach Fig. 4F gemäß der Ausführungsform des Verfahrens;

Fig. 4J

eine vergrößerte Detailansicht von Detail "J" gemäß Figur. 4I;

Fig. 4K

einen Verfahrensschritt zum Rollen der oberen Kante des Blechrohlings nach Fig. 4I gemäß der Ausführungsform des Verfahrens;

Fig. 4L

eine vergrößerte Detailansicht von Detail "L" gemäß Figur. 4K;

Fig. 4M

eine vergrößerte Detailansicht von Figur 4L;

Fig. 5A

eine Draufsicht eines nicht umgeformten Deckels;

Fig. 5B

eine Längsschnittansicht eines umgeformten Deckels;

Fig. 6A

die Verfahrensschritte zum Einführen und Versiegeln des umgeformten Deckels nach Fig. 5B mit dem Blechrohling;

Fig. 6B

die nach dem Einführen und Versiegeln erhaltene Blechdose mit einer abstehenden Abziehlasche; und

Fig. 6C

eine vergrößerte Detailansicht von Detail "C" gemäß Figur. 6B.

Further details, advantages and features will become apparent from the following description of an embodiment in conjunction with the drawings. In this drawing show:

Fig. 1

a longitudinal sectional view of an embodiment of a tin can;

Fig. 2

an enlarged view of a conical opening portion of the tin after Fig. 1 ;

Fig. 3

a longitudinal sectional view of a lid of the tin can after Fig. 1 ;

Fig. 4A-4B

a step of separating a raw material according to an embodiment of a method of manufacturing a sheet blank;

Fig. 4C

an enlarged detail view of detail "C" according to Figure. 4B ;

Fig. 4D

a method step for drawing a bottom portion of the sheet metal blank after Fig. 4B according to the embodiment of the method;

Fig. 4E

an enlarged detail view of detail "E" according to Figure. 4D ;

Fig. 4F

a method step for crimping the bottom portion after Fig. 4D and an upper portion of the sheet blank according to the embodiment of the method;

Fig. 4G

an enlarged detail view of detail "G" according to Figure. 4F ;

Fig. 4H

an enlarged detail view of detail "H" according to Figure. 4F ;

Fig. 41

a method step for conecuring an opening portion of the sheet blank Fig. 4F according to the embodiment of the method;

Fig. 4J

an enlarged detail view of detail "J" according to Figure. 4I ;

Fig. 4K

a method step for rolling the upper edge of the sheet metal blank after Fig. 4I according to the embodiment of the method;

Fig. 4L

an enlarged detail view of detail "L" according to Figure. 4K ;

Fig. 4M

an enlarged detail view of FIG. 4L ;

Fig. 5A

a plan view of an unformed lid;

Fig. 5B

a longitudinal sectional view of a formed lid;

Fig. 6A

the process steps for inserting and sealing the reshaped lid after Fig. 5B with the sheet metal blank;

Fig. 6B

the tin can obtained after insertion and sealing with a protruding pull-tab; and

Fig. 6C

an enlarged detail view of detail "C" according to Figure. 6B ,

Fig. 1 shows a longitudinal sectional view of a molded tinplate tin 2 with an axial weld, not shown, a central cylindrical portion 4 and a formed aluminum foil cover 6. The cover 6 seals a conical opening portion 8 of the tin 2. The bottom portion 10 of the tin can 2 has a feeder 12 and is closed by a bottom 14 formed of tinplate.

Fig. 2 shows an enlarged view of the upper portion of the tin box 2. The opening portion 8 is conical and connects at its lower end 16 directly to the first end of an inwardly curved stiffening bead 9 (see also Fig. 4M ). The diameter of the conical opening portion increases from its lower end 16 to its upper end 18 to continuously, so that the inner peripheral surface 20 of the conical opening portion 8 is free of heels. At the upper end 18 of the conical opening portion 8, a bead 22 is formed, which projects beyond the lateral surface 24 of the central cylindrical portion 4. The inner peripheral surface 20 extending between the lower and upper ends 16, 18 (see Fig. 4L ) forms a contact surface for a conical edge portion 26 of the lid 6. The length of the edge portion 26 corresponds to the length L of the conical opening portion 8 (see Fig. 4L ). The lid 6 also has a circular base surface 28 which has a diameter which substantially corresponds to that of the central cylindrical portion 4. Between the inner circumferential surface 30 of the edge portion 26 (see Fig. 5B ) and the inner peripheral surface 20 of the opening portion 8, an aluminum-polyethylene-molded sealing layer 32 is formed.

The stiffening bead 9 formed on the inner circumference of the tin can 2 (see in particular FIG Figure 4M ) has a radius of curvature R2 of about 2 mm, and its first end directly adjoins the lower end 16 of the conical opening portion 8. The second end of the stiffening bead 9 immediately adjoins the upper end of the middle cylindrical portion 4. The transition from the first end of the stiffening bead 9 to the conical opening portion 8 and from the second end of the stiffening bead 9 to the central cylindrical portion 4 each has a radius of curvature R1 of approximately 1.2 mm. The length S of the reinforcing bead 9 in the direction of the longitudinal axis B is measured from the lower end 16 of the conical opening portion 8 to the upper end of the central cylindrical portion 4. The length S is about 4.5 mm. The lower end 16 of the conical opening portion 8 is in alignment with the upper end of the central cylindrical portion 4.

An angle α between the inner peripheral surface 20 of the conical opening portion 8 and an axis A offset parallel to the longitudinal axis B of the tin box 2 is 9 ° (see FIG Fig. 6A ). An angle β between the conical edge portion 26 and the axis A is also 9 ° (see Fig. 6A ).

Fig. 3 For a simplified illustration, only a longitudinal sectional view of the cover 6 is shown. In order to pull off the cover 6, a pull tab 34 is formed integrally in the longitudinal extent of a portion of the conical edge portion 26. In the Fig. 3 Abziehlasche 34 shown is arcuate and has a first parallel to the conical edge portion 26 extending portion 36 and a second parallel to the base 28th extending section 38. Fig. 3 also shows the sealing layer 32 formed on the inner peripheral surface of the skirt portion 26.

Hereinafter, a method of manufacturing the can 2 will be described.

Fig. 4A shows a welded from tinplate and along its longitudinal sides double hull 40, which serves as a starting material for the production of the tin box 2. The double hull 40 is separated along a dividing line 42 into individual sheet metal blanks 44 (see Fig. 4B ). As part of the separation process, the upper end portion 46 of the sheet blank 44, along which the separation process is performed, relative to the longitudinal axis of the sheet metal blank 44 is formed to the outside. This slight deformation is in Fig. 4C shown in more detail.

Fig. 4D shows how subsequently the other end portion 48, ie the bottom portion 48 of the sheet metal blank 44 is retracted to a as in Fig. 4E shown cylindrical indentation 50 having a smaller diameter than the central cylindrical portion 4. The sheet metal blank 44 is then as in Fig. 4F Shown at both end portions 46 and 48 simultaneously crimped to form upper and lower outwardly bulging edge portions 52 and 54, respectively. FIGS. 4G shows that the upper edge portion 52 is formed by further reshaping the upper end portion 46 as a rounded edge portion 52. Fig. 4H shows the bottom portion 48 after the bead, in which the rounded lower edge portion 54 is formed.

Fig. 4I FIG. 15 shows the step of forming the tapered opening portion 8. The sheet blank 44 is deformed after being both-side crimping by butting immediately following the lower end of the upper edge portion 52. By the conification, the opening portion 8 is formed at an angle of 9 °. The upper end 18 of the conical opening portion 8 closes as in FIG Fig. 4J shown immediately and paragraph free at the upper rounded edge portion 52 and the lower end 16 of the conical opening portion also connects directly and paragraph-free to the central cylindrical portion 4 at. By the conifying only the immediately adjacent to the lower end of the rounded edge portion 52 area is transformed. The rounded upper edge portion 52 is further processed subsequently to bevel to form the bead 22.

By the conification, the conical opening portion 8 is formed so that its diameter continuously increases from its lower end 16 to its upper end 18 and thus forms a smooth surface. The conical opening portion 8 thus has the length L (see Fig. 4L ).

Fig. 4K shows that immediately after the conification, the upper edge portion 52 is radially rolled, whereby the bead 22 as in Fig.4L is formed, which extends over the lateral surface 24.

Figure 4M shows that after forming the bead 22, the stiffening bead 9 is formed radially inwardly with respect to the sheet blank 44. The stiffening bead 9 is formed by forming so that both the transition to the conical opening portion 8 and the transition to the central cylindrical portion 4 has a radius of curvature R1. The shaped stiffening bead 9 has a radius of curvature R2.

Fig. 5A shows the cut out of an aluminum foil cover 6 in its initial state. The lid 6 is cut in one piece with the pull tab 34 and then formed by deep drawing, so that the conical edge portion 26 is wrinkle-free. At least the portion of the aluminum foil which forms the conical edge portion 26 is coated with a sealing layer 32 formed of polyethylene, so that the inner peripheral surface 30 of the conical edge portion 26 is coated (see FIG. Fig. 3 ).

How out Fig. 5B can be seen, in which the sealing layer 32 is not shown, the pull-tab 34 extends in the longitudinal direction of the wrinkle-free conical edge portion 26th

The deep-drawn and coated lid 6 is detected by a sealing die, not shown, and transferred for attachment to the conical opening portion 8 of the sheet metal blank 44 to this. In particular, the upper side of the base surface 28 is sucked in by the sealing punch. During the transfer of the lid 6, the polyethylene layer 32 is heated by the heated sealing die.

Fig. 6A shows how the provided with the heated polyethylene layer 32 cover 6 is inserted into the opening of the sheet metal blank 44. Thus, the lid 6 is inserted concentrically with the longitudinal axis of the can and applied to the inner peripheral surface 20 of the conical opening portion 8, so that the inner peripheral surface 30 of the conical edge portion 26 completely with the interposition of the polyethylene layer 32 at this is applied. By preheating the aluminum foil with the polyethylene layer 32, a reliable seal is achieved. In particular, this prevents the conical edge section 26 from being drawn off from the conical opening section 8 as a result of the removal of the sealing punch. Since the sheet in the conical opening portion 8 has a temperature far below the melting temperature of the polyethylene layer 32, it absorbs the heat energy discharged through the polyethylene layer 32. The conical edge portion 26 is pressed against the conical opening portion 8 by the conical side of the sealing die, whereby a uniform distribution of the polyethylene layer 32 between the conical edge portion 26 and the conical opening portion 8 is achieved.

Fig. 6B shows a side view of the can 2 with protruding Abziehlasche 34 after sealing. How out Fig. 6C As can be seen, the conical edge portion 26 abuts completely against the conical opening portion 8.

After sealing the opening with the lid 6, the pull tab 34 is bent so that the first portion 36 parallel to the conical edge portion 26 and the second portion 38 parallel to the base 24 as in Fig. 3 shown extends.

The obtained tin can 2 is then turned over and filled with non-sterilizable products, such as peanuts or coffee and then closed in a conventional manner with a shaped bottom plate 14.

LIST OF REFERENCE NUMBERS

2

tin can

4

middle cylindrical section

6

cover

8th

conical opening section

9

reinforcing bead

10

bottom section

12

collection

14

ground

16

lower end of the opening portion 8

18

upper end of the opening portion 8

20

Inner peripheral surface of the opening portion 8

22

beading

24

Lateral surface of the central cylindrical portion. 4

26

Edge portion of the lid. 6

28

circular base of the lid 6

30

Inner peripheral surface of the edge portion 26

32

sealing layer

34

pull tab

36

first portion of the pull tab 34

38

second section of the pull tab 34

40

double hull

42

parting line

44

sheet metal blank

46

upper end portion of the sheet blank 44th

48

Bottom section of the sheet metal blank 44

50

collection

52

upper edge section

54

lower edge section

L

Height of the conical opening portion 8

B

Longitudinal axis of the tin can 2

α

Angle between the inner peripheral surface 20 and the longitudinal axis L.

β

Angle between the inner peripheral surface 30 and the longitudinal axis L.

A

axis

R1; R2

radius of curvature

S

Length of stiffening bead 9

Claims (21)

A tin can (2) having an axial weld, a central cylindrical portion (4) and a conical mouth portion (8) sealable with a lid (6) of a sheet material,
characterized by means for stiffening the conical opening portion (8). Tin can (2) according to claim 1, characterized in that the means in the circumferential direction between the conical opening portion (8) and the central cylindrical portion (4) in the form of a stiffening bead (9) is formed. Tin can (2) according to claim 2, characterized in that the stiffening bead (9) projects inwards towards the longitudinal axis of the tin can (2) and has a radius of curvature of between 1 mm to 3 mm. Tin can (2) according to claim 2 or 3, characterized in that the stiffening bead (9) with its first end directly to the conical opening portion (8) and with its second end directly to the central cylindrical portion (4). Tin can (2) according to claim 4, characterized in that the transition from the first end to the conical opening portion (8) and from the second end to the central cylindrical portion (4) each have a radius of curvature between 0.8 mm and 1.6 mm. Tin can (2) according to one of the preceding claims, characterized in that
the lid (6) has a circular base (28) and a conical edge portion (26) and that
the inner peripheral surface (30) of the edge portion (26) fully abuts with the interposition of a thermoplastic sealing layer (32) on the inner circumferential surface (20) of the conical opening portion (8). Tin can (2) according to claim 6, characterized in that the conical edge portion (26) and the conical opening portion (8) are each offset by 8 ° to 12 ° relative to the longitudinal axis (B) of the tin can (2) to the outside. Tin can (2) according to claim 6 or 7, characterized in that for pulling off the cover (6) of the conical opening portion (8) formed on the conical edge portion (26) Abziehlasche (34) is formed. Tin can (2) according to claim 8, characterized in that the pull tab (34) is formed integrally with the conical edge portion (26) by cutting out the foil material and is arcuate such that a first portion (36) of the pull tab (34) is parallel to the conical edge portion (26) and a second portion (38) of the pull tab (34) extending parallel to the circular base (28). A method of making a can (2) having an axial weld, a central cylindrical portion (4), and a conical mouth portion (8) sealable with a lid (6) of sheet material, comprising the steps of: Bending a plate-shaped starting material to form a cylindrical sheet metal blank, Longitudinally welding along the longitudinal sides of the sheet metal blank to form a cylindrical sheet metal blank (44) with the axial weld; and, characterized by Forming a means for stiffening the conical opening portion (8). A method according to claim 10, characterized by forming the sheet metal blank (44) between the conical opening portion (8) and the central cylindrical portion (4) to form the means in the form of a circumferential stiffening bead (9). A method according to claim 11, characterized in that the sheet metal blank (44) between the conical opening portion (8) and the central cylindrical portion (4) is pressed inwardly toward the longitudinal axis of the sheet metal blank (44) that the stiffening bead (9). is formed with a radius of curvature between 1 mm to 3 mm. A method according to claim 11 or 12, characterized in that a first end of the stiffening bead (9) immediately adjacent to the conical opening portion (8) and a second end of the stiffening bead (9) immediately adjacent to the central cylindrical portion (4) becomes. A method according to claim 13, characterized in that a radius of curvature between 0.8 mm and 1.6 mm respectively at the transition from the first end to the conical opening portion (4) and at the transition from the second end to the central cylindrical portion ( 4) is formed. A method according to claim 10 to 14, characterized by , cutting out the cover (6) with a pull tab (34) of the film material, forming the lid (6) to form a circular base (28) and a conical edge portion (26), wherein at least the the region of the film material forming the conical edge section (26) is coated with a thermoplastic sealing layer (32). A method according to claim 15, characterized in that the step of forming the lid (6) comprises: Deep drawing the cover (6) to form the circular base (28) and the conical edge portion (26) such that the conical edge portion (26) is made smooth. Method according to one of claims 15 or 16, characterized by ,
Engaging the deformed lid (6) with a heatable platen which heats the thermoplastic sealant layer (32) upon transfer of the formed lid (6) to the welded sheet blank (44),
Inserting the formed lid (6) into the conical opening portion (8) of the welded sheet metal blank (44),
Applying the conical edge portion (26) to the conical inner peripheral surface (20) of the opening portion (8) such that the conical edge portion (26) with the interposition of the heated thermoplastic sealing layer (32) is fully applied to the conical inner peripheral surface (20) and the conical opening portion (8) the welded sheet metal blank (44) is hermetically sealed, whereby the sealed with the lid (6) tin box (2) is obtained. A method according to any one of claims 17, characterized in that the lid (6) is inserted such that the lower edge of the conical edge portion (26) is located in the region of the transition from the first end of the stiffening bead to the conical opening portion (4). A method according to claim 17 or 18, characterized in that the punch the conical edge portion (26) on the colder inner peripheral surface (20) of the opening portion (8) applies and before the sheet is reached the melting temperature of the sealing layer (32). A method according to any one of claims 16 to 19, characterized in that after sealing, the pull tab (34) formed on the conical edge portion (26) is deformed such that a first portion (36) of the pull tab (34) is parallel to the conical one Edge portion (26) and a second portion (38) of the Abziehlasche (34) extends parallel to the circular base surface (28). Method according to one of claims 10 to 20, characterized in that the conical edge portion (26) and the conical opening portion (8) for positive attachment to each other by 8 ° to 12 ° relative to the longitudinal axis (B) of the tin can (2) be reshaped on the outside.

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