Attachment unit for attaching a container element, and apparatus for attaching container elements

Abstract

The present disclosure relates to an attachment unit for attaching a container element to a container body. The attachment unit comprises a retaining device adapted to retain the container body while the container element is being attached to the container body and an applicator for positioning the container element in the container body. The retaining device comprises at least one through-going positioning cavity being adapted to receive a portion of the container body. The applicator is aligned with the positioning cavity, such that the container element is displaceable by means of the applicator into the container body by moving at least partly through the positioning cavity of the retaining device. The attachment unit comprises an internal housing arranged to provide and maintain a protective gas atmosphere above the positioning cavity of the retaining device. The internal housing is adapted to at least partly enclose the applicator.

Claims

1. An apparatus for attaching container elements to container bodies formed from paperboard web material in a flow of containers, said apparatus comprising: a transport means configured to transport said flow of containers through said apparatus, at least one attachment unit arranged along said transport means, and an external housing arranged to enclose said transport means and said at least one attachment unit, wherein the attachment unit comprises: a retaining device, adapted to retain said container body while said container element is being attached to said container body, an applicator for positioning said container element in said container body, said retaining device comprises at least one through-going positioning cavity being adapted to receive a portion of said container body, said applicator is aligned with said positioning cavity, such that said container element is displaceable by means of said applicator into said container body by moving at least partly through said positioning cavity of said retaining device, characterized in that said attachment unit comprises an internal housing arranged to provide and maintain a protective gas atmosphere above said positioning cavity of said retaining device, said internal housing is adapted to at least partly enclose said applicator, said retaining device forms a bottom of said internal housing or is enclosed by said internal housing, and a portion of said attachment unit is located outside of said internal housing.

2. The apparatus according to claim 1, wherein said internal housing comprises an opening, through which a rod comprised in said applicator may move.

3. The apparatus according to claim 1, wherein said internal housing comprises a gas inlet.

4. The apparatus according to claim 1, wherein said retaining device comprises a welding unit, preferably arranged around said positioning cavity, said welding unit being adapted to weld said container element to said container body, e.g. said welding unit comprising a coil extending around said positioning cavity.

5. The apparatus according to claim 1, wherein said attachment unit further comprises a transfer plate for transferring said container element between a first position and a second position, said transfer plate extending in a first direction and a second direction being perpendicular to each other, said transfer plate comprising at least one through-going transfer cavity adapted to receive and hold said container element, said transfer plate being displaceable between said first position, in which said transfer plate is adapted to receive said container element in said transfer cavity, and said second position in which said transfer cavity is aligned with said positioning cavity of said retaining device, said transfer plate in said second position being located between said applicator and said positioning cavity of said retaining device, such that said container element is displaceable by means of said applicator from said transfer cavity in said transfer plate into said container body by moving through said transfer cavity and at least partly through said positioning cavity of said retaining device, said transfer plate being displaceable between said first and second positions by translational movement relative to said internal housing in a gap comprised in said internal housing, wherein in said first position of said transfer plate said transfer cavity is outside said internal housing and in said second position of said transfer plate said transfer cavity is inside said internal housing.

6. The apparatus according to claim 5, wherein said transfer plate further comprises a cover portion being at least as large as or substantially as large as an open area of said positioning cavity.

7. The apparatus according to claim 6, wherein said cover portion is arranged adjacent to said transfer cavity as seen in said second direction.

8. The apparatus according to claim 6, wherein said cover portion has a minimum extension in said second direction which is at least 1.0 times a maximum extension in said second direction of said open area of said positioning cavity, preferably at least 1.2 times, more preferably at least 1.4 times.

9. The apparatus according to claim 5, wherein said transfer plate comprises one or more holding elements adapted to hold said container element in said transfer cavity, said one or more holding elements being located at a wall of said transfer cavity, preferably at a centre of a side of said wall.

10. The apparatus according to claim 5, wherein said transfer plate comprises one or more indentations adapted to allow space for gripping of said container element, said indentation preferably being located at a corner of said transfer cavity.

11. The apparatus according to claim 1, wherein said retaining device comprises a plurality of positioning cavities and said attachment unit comprises a plurality of applicators aligned with said positioning cavities, such that each applicator is associated with a respective positioning cavity, preferably said positioning cavities and said applicators being arranged in a row.

12. The apparatus according to claim 11, wherein said plurality of applicators are adapted to simultaneously position said plurality of container elements in said respective container bodies.

13. The apparatus according to claim 1 comprising a first attachment unit arranged along said transport means arranged to attach a disc, e.g. a bottom disc, to said container body, a second attachment unit according to claim 1 arranged along said transport means arranged to attach a reinforcing rim to said container body, said second attachment unit being located downstream of said first attachment unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will hereinafter be further explained by means of non-limiting examples with reference to the appended drawings wherein:

(2) FIG. 1 shows an apparatus according to the invention for attaching container elements to container bodies in a flow of containers in a perspective view.

(3) FIG. 2 shows an inside of the apparatus of FIG. 1.

(4) FIG. 3 shows an exemplary container, for which the apparatus is suitable.

(5) FIG. 4 shows an attachment unit for attaching a container element according to the invention with a transfer plate in a first position.

(6) FIG. 5 shows the attachment unit with the transfer plate in a second position.

(7) FIG. 6 shows the transfer plate.

(8) FIG. 7 shows an internal housing.

(9) It should be noted that the appended drawings are schematic and that individual components are not necessarily drawn to scale and that the dimensions of some features of the present invention may have been exaggerated for the sake of clarity.

DETAILED DESCRIPTION

(10) The invention will, in the following, be exemplified by embodiments. It should however be realized that the embodiments are included in order to explain principles of the invention and not to limit the scope of the invention, as defined by the appended claims. Details from two or more of the embodiments may be combined with each other.

(11) FIGS. 1 and 2 illustrate an apparatus 1 according to the invention for attaching container elements to container bodies in a flow of containers. FIG. 3 shows an exemplary container 101, for which the apparatus 1 is suitable.

(12) The apparatus 1 comprises a transport means 3 configured to transport the flow of containers through the apparatus 1 and an attachment unit 5 for attaching a container element to a container body. An external housing 7 is arranged to enclose the transport means 3 and the attachment unit 5. FIG. 1 shows a perspective view of the apparatus 1, while FIG. 2 shows an inside of the apparatus 1 with the external housing 7 removed for better visibility.

(13) The apparatus 1 is suitably used for paperboard packaging containers 101 for pourable or scoopable bulk solids, like the one illustrated in FIG. 3. The particular shape of the container 101 shown in the figures should not be considered limiting to the invention, since the apparatus 1 is suitable for containers of any useful shape or size.

(14) The container 101 comprises a container body 103 formed by a tubular container wall 105. The container wall 105 extends in a height direction H of the container 101 from a bottom end edge 107 at a bottom end of the container body 103 to an upper end edge 109 at an upper end of the container body 103. The container body 103 has an upper body opening 111 at the upper end and a bottom body opening 113 at the bottom end. A bottom disc 115 is positioned at the bottom end of the container body 103 and covers the bottom body opening 113. The container body 103 is made from paperboard material as defined herein. The container body 103 may be formed by bringing together the side edges of a web of paperboard causing the material to assume a tubular shape, whereafter the side edges are sealed together. Sealing of the side edges may be made by any suitable method as known in the art, such as by welding or gluing, with welding being preferred. Sealing of the side edges of the container body web may involve using a sealing strip which is applied over the join between the side edges, as known in the art. The bottom disc 115 may be made from paperboard, metal, plastic, or from any suitable combination of such materials as known in the art. The bottom disc 115 may have a folded edge wall 116.

(15) The bottom end edge 107 is reinforced by a reinforcing bottom rim 117 which is applied to the inner surface of the container wall 105 and/or to the folded edge wall 116 of the bottom disc 115, between the bottom disc 115 and the bottom end edge 107. In the illustrated embodiment, the bottom rim 117 has an outwardly directed flange 119 which covers the bottom end edge 107 and forms a bottom edge of the container 101. The bottom rim 117 reinforces the bottom end edge 107, stabilizes the shape of the container body 103 and protects the bottom edge 107 from mechanical deformation. The bottom rim 117 also serves as a protective barrier against water and other fluids which may be present on a surface on which the container 101 is placed. The bottom rim 117 delimits a downwardly open space between the bottom disc 115 and the bottom edge of the container 101, which may be used to accommodate stacking elements arranged at an upper end of another container when stacking two or more containers on top of each other.

(16) As an alternative to the illustrated bottom rim 117, the bottom edge of the container may be formed by a rolled edge of the container body 103, or may be provided by a simple, non-rolled join between the bottom disc 115 and the container body 103.

(17) The container 101 is provided with a closure arrangement comprising a lid 121 and a reinforcing upper rim 123 extending along the container body opening edge 109. The lid 121 comprises a planar disc 125. The exemplary container 101 is further provided with a fully or partly removable sealing disc 127 which is adapted to be sealed to the container body wall 105.

(18) The bottom disc 115, the bottom rim 117, the lid 121, the upper rim 123 and the sealing disc 127 are examples of container elements for which the apparatus 1 is suitably used to attach the container element to the container body 103.

(19) The bottom rim 117 and the upper rim 123 are typically made of plastics. As may be gleaned in FIG. 3, the bottom rim 117 and the upper rim 123 form closed loops with a main extension in a loop plane. The closed loop encloses an open space in the centre. The bottom rim 117 and the upper rim 123 also have a respective extension in the height direction H of the container 101. Thereby, the closed loop defines an inner volume of the bottom rim 117 and the upper rim 123, respectively.

(20) The bottom disc 115, the lid 121 and the sealing disc 127 are adapted to extend over the cross-section of the container body. Although the sealing disc 127 is a substantially two-dimensional component, the bottom disc 115 and the lid 121 extend also in the height direction H of the container 101, such that their interiors define an inner volume, which is filled by gas, e.g. air.

(21) Going back again to FIGS. 1 and 2, it can be seen that a conveyor feeds container bodies 103 to the apparatus 1. Another conveyor feeds containers 101 away from the apparatus 1. In the exemplary illustrated embodiment of the apparatus 1, it is assumed that the sealing disc 127, the upper rim 123 and the lid 121 have already been attached to the container body 103, when it enters the apparatus 1. Further, it is assumed that the material to be contained in the container 101 has been filled into the interior of the container body 103 in a filling unit located upstream of the apparatus 1. Hence, the containers 101 are transported through the apparatus 1 standing upside down, i.e. standing on the lid 121.

(22) FIG. 2 shows of the inside of the apparatus 1. Following a running direction R of the apparatus 1, the transport means 3 comprises an inlet conveyor member 9, a feeding arrangement 11 in the form of two feed screw members at respective opposite sides of the container body 103, whereof one of the feed screw members can be seen in FIG. 2, a main conveyor member 13, a first movable gripping arrangement 15, a second movable gripping arrangement 17, an outlet conveyor member 19 arranged downstream of the attachment unit 5 and a stationary sliding plate 21 arranged at the outlet of the apparatus 1. The components 9, 11, 13, 15, 17, 19, 21 of the transport means 3 are exemplary and are similar to the ones described in WO 2013/009226 A1, to which document reference is made for further details.

(23) The attachment unit 5, which is further described below in conjunction with FIGS. 4 and 5, is located between the main conveyor member 13 and the outlet conveyor member 19 as seen in the running direction R of the apparatus 1. The first movable gripping arrangement 15 and the second movable gripping arrangement 17 move the container bodies 103 to and from the attachment unit 5. In the illustrated embodiment, the attachment unit 5 is adapted to attach bottom rims 117 to the container bodies 103. It has been found suitable to simultaneously attach a plurality of bottom rims 117 to a plurality of corresponding container bodies 103, in order to increase the running speed of the apparatus 1. In the illustrated embodiment, four bottom rims 117 are attached at the same time to respective container bodies 103. However, it could also be suitable to attach the bottom rims 117 one by one after each other or to attach any other number of bottom rims 117 than four, e.g. two, three, six, eight or ten, at the same time.

(24) The apparatus 1 may as an option, not illustrated, comprise an additional attachment unit, which is adapted to attach a bottom disc 115 to the container body 103. The additional attachment unit is in that case located upstream of the illustrated attachment unit 5. Similar as for the bottom rims 117, bottom discs 115 can be attached to a plurality of container bodies 103 at the same time, preferably for the same number of container bodies 103 as for attaching the bottom rims 117.

(25) The external housing 7 encloses the transport means 3 and the at least one attachment unit 5. The external housing 7 is adapted to protect the apparatus 1 and to provide and maintain a protective gas atmosphere inside the apparatus 1. The protective gas may be nitrogen, carbon dioxide or a mixture of nitrogen and carbon dioxide. It is therefore preferable that the external housing 7 forms a gas chamber, which is as closed as possible in order to minimize losses of the protective gas and/or to minimize entrance of the surrounding air. However, the external housing 7 may be open downwards.

(26) As an option, degassing of the container may be performed, when filling the material, e.g. the bulk solids, into the container. The degassing may comprise supplying a protective gas to the flow of material to be contained in the container during filling. The protective gas may be nitrogen, carbon dioxide or a mixture of nitrogen and carbon dioxide. The protective gas may be blown into the flow of material before the material reaches the container. If the material is treated with protective gas during filling, the containers are preferably conveyed to the apparatus 1, while maintaining the protective atmosphere, e.g. by moving the containers through a tunnel filled with protective gas. Alternatively, the filled containers may be introduced in a vacuum chamber to draw off air, whereafter the containers are subjected to a protective gas atmosphere and closed.

(27) Even if it is assumed in the illustrated embodiment that the material to be contained in the container has been filled in the container upstream of the apparatus 1, it would also be possible to locate the filling unit inside the external housing 7 of the apparatus. The external housing could in that case enclose the filling unit and/or one or more units for attaching the sealing disc 127, the upper rim 123 and the lid 121.

(28) FIGS. 4 and 5 illustrate the attachment unit 5 for attaching a container element according to the invention. As mentioned above in conjunction with FIGS. 1 and 2, the illustrated embodiment shows attachment of the bottom rim 117. However, such an attachment unit would also be suitable for attachment of the bottom disc 115, the lid 121, the upper rim 123 or the sealing disc 127. The attachment unit 5 comprises a retaining device 23, a supporting device 25, an applicator 27 and a transfer plate 29.

(29) An example of a transfer plate 29 is illustrated in FIG. 6. The transfer plate 29 extends in a first direction x, parallel to the running direction R of the apparatus 1, and a second direction perpendicular to first direction x and coinciding with the transverse direction of the apparatus 1. The transfer plate 29 comprises a cavity portion 31 with at least one through-going transfer cavity 33 adapted to receive and hold the container element 117. The transfer cavity 33 has an open area A.sub.1 and is configured to retain the container element, e.g. the bottom rim 117.

(30) In order to minimize, or preferably avoid, unnecessary loss of the protective gas, the shape of the transfer cavity 33 is corresponding to the shape of the container element, e.g. the bottom rim 117. In case the container element is to comprise a folded edge wall when mounted in the container, e.g. the bottom disc 115, the open area A.sub.1 may correspond to the unfolded surface of the container element. The open area A.sub.1 is then less than that of the container element, wherein the area difference corresponds to the portion of the container element being folded into the folded edge wall 116. Such a folded edge 116 wall may typically have a width in the range of from 1 to 10 mm, preferably in the range of from 2 to 5 mm.

(31) A wall of the transfer cavity 33 may comprise holding elements 34 adapted to hold the container element in the transfer cavity 33. Such holding elements 34 are especially useful when the container element does not comprise a disc shape, but instead forms a loop, which comprises an inner volume filled by gas, e.g. air, such as the bottom rim 117 or the upper rim 123. If the container element instead comprises a disc shape, such as the bottom disc 115, the lid 121 or the sealing disc 127, the holding elements 34 may be omitted.

(32) In the illustrated embodiment, there are four such holding elements 34 adapted to hold each of the sides of the container element, which in the illustrated embodiment is substantially rectangular, preferably at a centre of each side. It would be feasible to use one, two, three, four or more such holding elements 34. The holding elements 34 may be resilient, e.g. due to material properties or by being biased by a spring. As an alternative, or a complement, the container element itself may be resilient, e.g. due to material properties. The holding elements 34 may be utilized to compensate for tolerances regarding the dimensions of the container element 115, 117, 121, 123, 127 and/or the transfer cavity 33. In addition, or as a complement, the holding elements 34 may be used to temporarily press the sides of the container element, e.g. the bottom rim 117, inwards, such that the container element will be easier to insert into the container body 103, thereby lowering or avoiding the risk of damaging the edges of the container body 103 during insertion of the bottom rim 117.

(33) The transfer plate 29 comprises a cover portion 35 being at least as large as, or substantially as large as, the open area A.sub.1 of the transfer cavity 33. The cover portion 35 is arranged adjacent to the cavity portion 31 as seen in the second direction y. The cover portion 35 has a minimum extension y.sub.1 in the second direction y, which is at least 1.0 times a maximum extension y.sub.2 in the second direction y of the area A.sub.1 of the transfer cavity 33, preferably at least 1.2 times, more preferably at least 1.4 times.

(34) In order to facilitate placing the container element 115, 117, 121, 123, 127 into the transfer cavity 33, there are in the illustrated embodiment of FIG. 6 indentations 36 intended to allow space for gripping members 44a, 44b, 44c, 44d. See below for further description of the gripping members. If utilizing holding elements 34, the indentations 36 are preferably located not to interfere with the holding elements 34. The indentations 36 may thus be located in the corners of the transfer cavity 33. Such gripping members 44a, 44b, 44c, 44d with their corresponding indentations 36 are especially useful when the container element does not comprise a disc shape, but instead forms a loop, which comprises an inner volume filled by gas, e.g. air, such as the bottom rim 117.

(35) If the container element comprises a disc shape, such as the bottom disc 115, the lid 121 and the sealing disc 127, the container element 115, 121, 127 may instead by placed into the transfer cavity 33 by means of e.g. a suction cup. In that case, the indentations 36 may be omitted. However, suction cups are not suitable when the container elements form a loop.

(36) In the illustrated embodiment, there are four cavity portions 31 arranged in a row as seen in the first direction x. Each cavity portion 31 comprises a respective transfer cavity 33 and is arranged together with a corresponding respective cover portion 35.

(37) The retaining device 23 is adapted to retain the container body 103 while the container element, illustrated as the bottom rim 117, is being attached to the container body 103. The retaining device 23 comprises at least one through-going positioning cavity 37 with an open area A.sub.2 corresponding to that A.sub.1 of the transfer cavity 33, the positioning cavity 37 being adapted to receive a portion of the container body 103. The size and shape of the cover portion 35 of the transfer plate 29 is selected, such that the cover portion 35 is able to cover, or at least substantially cover, the open area A.sub.2 of the positioning cavity 37.

(38) The supporting device 25 is adapted to support the container body 103 and to position the container body 103 in the retaining device 23.

(39) The applicator 27 is adapted to position the container element 117 in the container body 103. Hence, the applicator 27 is aligned with the positioning cavity 37 as seen in a vertical direction z. The applicator 27 is vertically adjustable and capable of pressing down the container element into the container body 103 to the desired attachment position. Preferably, the applicator 27 is further expandable in a radial direction of the positioning cavity 37 to be able to press a vertical portion of the container element circumferentially in a direction towards a wall of the positioning cavity 37, i.e. to press against an inside of the container wall 105 of the container body 103 placed in of the positioning cavity 37.

(40) In the illustrated embodiment, the transfer plate 29 comprises four cavity portions 31 arranged in a row as seen in the first direction x. In a corresponding way, the retaining device 23 comprises the same number of positioning cavities 37, i.e. four. Further, the supporting device 25 is adapted to support the same number of container bodies 103, i.e. four, and to position the portions of them in the respective positioning cavities 37 of the retaining device 23. In addition, the attachment unit 5 comprises the same number of applicators 27, i.e. four, aligned with the positioning cavities 37, such that each applicator 27 is associated with a respective positioning cavity 37. With this configuration, it is possible to attach a number of, container elements simultaneously, here four at the same time. Similar as for the transfer plate 29, the positioning cavities 37 and the applicators 25 are arranged in a row as seen in the first direction x.

(41) The transfer plate 29 is displaceable between a first position and a second position. In the first position, see FIG. 4, the transfer plate 29 is adapted to receive the container element 117 in the transfer cavity 33. Further, the transfer plate 29 is positioned, such that the cover portion 35 covers or substantially covers the open area A.sub.2 of the positioning cavity 37. Thereby, a loss of the protective gas through the positioning cavity 37 is minimized, or preferably avoided.

(42) In the second position, see FIG. 5, the transfer cavity 33 is aligned with the positioning cavity 37 of the retaining device 23 and hence also with the applicator 27. First the transfer plate 29 is located vertically between the applicator 27 and the positioning cavity 37 of the retaining device 23. Thereby it is possible for the applicator 27 to displace the container element 117 from the transfer cavity 33 in the transfer plate 29 into the container body 103 by moving through the transfer cavity 33 and at least partly through the positioning cavity 37 of the retaining device 23. In the illustrated embodiment, the container element is constituted by the bottom rim 117. Therefore, the container body 103 is held upside down, such that its bottom end opening 113 faces upwards.

(43) In order to attach the container element 117 to the container body 103, the retaining device 23 comprises a welding unit 39, preferably arranged around the positioning cavity 37. The welding unit 39 is adapted to weld the container element 117 to the container body 103, e.g. the welding unit 39 comprising a coil extending around the positioning cavity 37. If the applicator 27 is expandable in a radial direction of the positioning cavity 37, the container element can be pressed against the welding unit 39. Any suitable welding technique may be used, such as ultrasonic welding or high frequency welding, with high frequency welding being preferred.

(44) As an alternative or a complement to welding, an adhesive may be applied to the container element before attaching it to the container body.

(45) An exemplary method of attaching a container element 117 to a container body 103 by means of an attachment unit 5 as disclosed herein comprises: Positioning the transfer plate 29 in the first position, see FIG. 4. Placing the container element 117 in the transfer cavity 33. Displacing the transfer plate 29 to the second position, see FIG. 5. Displacing the container element 117 from the transfer cavity 33 in the transfer plate 29 into the container body 103 by means of the applicator 27 by moving through the transfer cavity 33 and at least partly through the positioning cavity 37 of the retaining device 23. Fixing the container element 117 to the container body 103, e.g. by means of welding and/or an adhesive.

(46) Thereafter the transfer plate 29 is displaced back to the first position and the cycle can start again.

(47) The container element is placed in the transfer cavity 33 of the transfer plate 29 by means of a container element supplier 41 comprising at least one gripping unit 42. A pile of container elements, e.g. bottom rims 117, are stored in a magazine 43. The number of piles in the magazine 43 and the number of gripping units 42 correspond to the number of transfer cavities 33 in the transfer plate 29, in the illustrated case four piles. The gripping unit 42 is able to grip a single container element, here the bottom rim 117, move it from an opening 45 in the magazine 43 and place it in the corresponding transfer cavity 33. In the illustrated embodiment, four single container elements 117 are gripped at the same time. The gripping unit 42 comprises four gripping members 44a, 44b, 44c, 44d, which grip at the corners of the container element 117. The positions of the gripping members 44a, 44b, 44c, 44d correspond to the positions of the indentations 36 of the transfer plate 29.

(48) The attachment unit 5 comprises an internal housing 47, see FIG. 7. The internal housing 47 is indicated by point-dashed lines in FIGS. 4 and 5. The internal housing 47 is located inside the external housing 7 and is arranged to provide an additional protective gas atmosphere above the positioning cavity 37 of the retaining device 23. The internal housing 47 comprises a gap 51 located at a first side wall 53 of the internal housing facing the container element supplier 41. The transfer plate 29 is displaceable within the gap 51 between the above-mentioned first and second positions by translational movement relative to the internal housing 47 in the gap 51, wherein in the first position of the transfer plate 29 the transfer cavity 33 is outside the internal housing 47, see FIG. 4, and in the second position of the transfer plate 29, the transfer cavity is inside the internal housing 47, see FIG. 5.

(49) Depending on the size of the internal housing 47, there may also be an additional gap 55, e.g. located at a second side wall 57 of the internal housing 47, which second side wall 57 is opposite to that of the first side wall 53. When the transfer plate 29 is in its second position, parts of the transfer plate 29, e.g. the cover portion 35, may protrude through the additional gap 55. See FIGS. 5 and 7.

(50) In the illustrated embodiment, the retaining device 23 forms a bottom wall of the internal housing 47, which partly encloses the applicator 27. A top wall of the internal housing 47 comprises four openings 49, through which the applicators 27 pass. The applicators 27 are axially displaceable in relation to the internal housing 47, such that the applicators 47 are able to perform the above-mentioned displacement of the applicators 47 through the transfer cavity 33 and at least partly through the positioning cavity 37 of the retaining device 23. One or more seals, e.g. bushings, may be located on a respective rod 50 of the applicators 27 and/or around circumferences of the openings 49 in order to prevent gas from leaking out from the internal housing 47. As an alternative, the internal housing may enclose the whole applicator or the retaining device.

(51) The internal housing 47 is provided with a gas inlet 59 for supplying additional protective gas.

(52) The internal housing 47 is especially useful when the container element does not comprise a disc shape, but instead forms a loop, which comprises an inner volume filled by gas, e.g. air, such as the bottom rim 117. In that case, the air being transported with the container element into the external housing 7 of the apparatus 1 is undesired, since it adds air to the protective gas. However, by utilizing the internal housing 47, the air is dispersed in the protective gas atmosphere of the internal housing 47 and hence the effect of the air is minimized. Further, by utilizing the internal housing 47, an amount of protective gas corresponding to the volume of air transported in the inner volume of the container element may be added to the internal housing 47 to retain the protective gas atmosphere. In case the above-mentioned welding unit 39 is utilized, the gas inlet 59 can be used to supply additional protective gas, such that it can be ascertained that there is no air, or substantially no air, present when welding. The amount of added gas thus preferably corresponds to at least the amount of air transported with the bottom rim 117.

(53) Further modifications of the invention within the scope of the appended claims are feasible. As such, the present invention should not be considered as limited by the embodiments and figures described herein. Rather, the full scope of the invention should be determined by the appended claims, with reference to the description and drawings.