A METHOD FOR THE MANUFACTURE OF COMPOSITE CANS AND A COMPOSITE CAN MADE BY THE METHOD
20220135260 · 2022-05-05
Assignee
Inventors
Cpc classification
B65B7/28
PERFORMING OPERATIONS; TRANSPORTING
B65B65/003
PERFORMING OPERATIONS; TRANSPORTING
B65B31/025
PERFORMING OPERATIONS; TRANSPORTING
B65B7/2842
PERFORMING OPERATIONS; TRANSPORTING
B65B43/08
PERFORMING OPERATIONS; TRANSPORTING
B65B1/02
PERFORMING OPERATIONS; TRANSPORTING
International classification
B65B1/02
PERFORMING OPERATIONS; TRANSPORTING
B65B1/04
PERFORMING OPERATIONS; TRANSPORTING
B65B31/02
PERFORMING OPERATIONS; TRANSPORTING
B65B43/08
PERFORMING OPERATIONS; TRANSPORTING
B65B65/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A method for manufacturing and filling a composite can (201), the method comprising: —forming a tubular body (203) by bending a body blank (16) and bringing two opposing edges of the body blank (16) together in an end-to-end join; —sealing the join by welding a sealing strip (214) over the join, thereby forming an intermediate can (403; 503); —sealing a top opening (211) by attaching a top sealing member (227) across the top opening (211); —applying a top rim (223) to the intermediate can (403; 503) by welding an inserted part of the top rim (223) to the inner surface of the tubular body (203); —turning the intermediate can (403; 503) upside-down and placing the intermediate can (403; 503) on a conveyor (2a) with the top rim (223) resting on the conveyor (2a); filling the intermediate can (403; 503) through the bottom opening (213); —sealing the bottom opening (213) of the tubular body (203) by attaching a bottom sealing member (215) across the bottom opening (213); —turning the intermediate can (403; 503) to bring the top rim (223) in an upward-facing position; —attaching a reclosable lid (221) at the top end of the tubular body (203). The intermediate can is kept in a protective gas atmosphere from said filling of said intermediate can until said bottom opening (213) of said tubular body (203) has been sealed. An assembly line (1) for manufacturing and filling of composite cans (201) is also disclosed.
Claims
1. A method for manufacturing a composite can and filling of dry or moist goods in said composite can, said method comprising: picking a body blank from a pile of body blanks and transferring said body blank to a body forming station; forming a tubular body by bending said body blank and bringing two opposing edges of said body blank together in an end-to-end join, said join extending in a height direction of said tubular body; sealing said join by welding a sealing strip over said join on an inner surface of said tubular body, thereby forming an intermediate can; transferring said intermediate can to a top sealing station; sealing a top opening at a top end of said tubular body by welding a peripheral flange of a top sealing member to said inner surface of said tubular body at a distance from a top end edge of said tubular body; transferring said intermediate can to a conveyor and placing said intermediate can on said conveyor a bottom opening at a bottom end of said tubular body facing upward in a vertical direction; transferring said intermediate can to a filling unit; filling said intermediate can with said dry or moist goods through said bottom opening of said tubular body; subjecting said intermediate can to a protective gas atmosphere either during said filling of said intermediate can or by introducing said filled intermediate can into a vacuum chamber to draw off air; transferring said filled intermediate can to a sealing unit, said filled intermediate can being transported to said sealing unit in a closed conveying system while maintaining said protective gas atmosphere; sealing said bottom opening of said tubular body by welding a peripheral flange of a bottom sealing member to said inner surface of said tubular body at a distance from a bottom end edge of said tubular body, sealing of said bottom opening being carried out while maintaining said protective gas atmosphere; turning said filled and bottom sealed intermediate can to bring said top end of said tubular body in an upward-facing position in said vertical direction and transferring said intermediate can to a lid attachment unit; and attaching a reclosable lid at said top end of said tubular body with an inner surface of said reclosable lid in direct contact with an upper surface of said top rim.
2. The method according to claim 1, wherein the following steps are performed after sealing of said top opening: transferring said intermediate can to a top rim application station; applying a top rim to said intermediate can by inserting at least a lower part of said top rim into said top opening, above said top sealing member; welding said inserted part of said top rim to said inner surface of said tubular body; transferring said intermediate can to said conveyor and placing said intermediate can on said conveyor with said top rim resting on said conveyor and said bottom opening at said bottom end of said tubular body-R facing upward in a vertical direction;
3. The method according to claim 1, wherein tightly fitted lead-in and outlet tunnels are arranged at an inlet and at an outlet of said sealing unit.
4. The method according to claim 1, wherein said method comprises supplying a protective gas such as nitrogen, carbon dioxide or a mixture of nitrogen and carbon dioxide to said dry or moist goods during filling of said intermediate can and/or after filling of said intermediate can.
5. The method according to claim 1, wherein said sealing unit is arranged in an external housing and is arranged to operate in a protective gas atmosphere in said external housing.
6. The method according to claim 5, wherein an outlet port for said intermediate can is arranged in said external housing of said sealing unit-, wherein a size of said outlet port is adapted to a size of said intermediate can being processed.
7. The method according to claim 6, wherein said outlet port comprises a short tunnel arranged at an end of an outlet conveyor member, wherein a stationary sliding plate constitutes a floor in said tunnel.
8. The method according to claim 6, wherein an inlet port for said intermediate can is arranged in said external housing of said sealing unit- and a closable hatch is arranged at said inlet port.
9. The method according to any one of the preceding claim 1, wherein said method further comprises: applying a bottom rim to said bottom end of said bottom sealed intermediate can; placing said bottom sealed intermediate can on a conveyor with said bottom rim resting on said conveyor-Rd) during said transfer of said intermediate can to said lid attachment unit.
10. The method according to claim 1, wherein a scoop is applied between said top sealing member and said reclosable lid before attaching said reclosable lid at said top end of said tubular body, said scoop being applied directly on said top sealing member or being placed in a scoop holder which is arranged above said top sealing member.
11. The method according to claim 1, wherein two or more intermediate cans are processed simultaneously during one or more of: sealing said top opening; applying said top rim; welding said top rim; filling said intermediate can; sealing said bottom opening; and attaching said reclosable lid.
12. An assembly line for manufacturing of composite cans and filling of dry or moist goods in said composite cans according to the method of claim 1, said assembly line comprising a plurality of machine units connected by conveyors, wherein said machine units comprise: a body forming unit; a filling unit; a sealing unit; and a lid attachment unit.
13. The assembly line according to claim 12, wherein a gas box is arranged between said filling unit and said sealing unit.
14. The assembly line according to claim 12, wherein said sealing unit comprises a can sealing station and a rim application station.
15. The assembly line according to claim 12, wherein said sealing unit is arranged in an external housing and is arranged to operate in a protective gas atmosphere in said external housing.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0181] The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein:
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DETAILED DESCRIPTION
[0191] The invention will, in the following, be exemplified by embodiments. 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.
[0192]
[0193] The illustrated assembly line 1 comprises a number of machine units 3-10 connected by conveyors 2a, 2b, 2c, 2d. In order from the beginning of the assembly line 1, the machine units are: a body forming unit 3, a filling unit 4, a gas box 5, a sealing unit 6, a cleaning unit 8, a can turning unit 9, a scoop insertion unit 10 and a lid attachment unit 7. A further conveyor 2e is arranged at the end of the assembly line 1 and is arranged to convey the produced composite cans from the lid attachment unit 7 and further e.g. to a packing apparatus (not shown).
[0194] Production of composite cans on the assembly line 1 is described below with reference to a single composite can. It is to be understood that while the assembly line 1 is run, multiple composite cans are continuously produced and are leaving lid attachment unit 7 at the end of the assembly line 1. As set out herein, the machine units of the assembly line 1 such as any can component attachment unit, may be configured to simultaneously process multiple intermediate cans such as 2, 3, 4, 5 or 6 intermediate cans. Exemplary can component attachment units 405, 406 are shown in
[0195] The body forming unit 3 includes: a body blank picking station 11, a body forming station 12, a top sealing station 13 and a top rim application station 14.
[0196] In the body blank picking station 11, a body blank 16 is picked from a pile of body blanks 16 and transferred to the body forming station 12. In the body forming station 12 a tubular body is formed by bending the body blank 16 and bringing two opposing edges of the body blank together in an end-to-end join, also known as a “butt join”. The join extends in a height direction H of the tubular body between a top end and a bottom end of the tubular body, as shown in
[0197] After forming the tubular body and applying the sealing strip, the intermediate can is transferred to the top sealing station 13 and the top opening at the top end of the tubular body is sealed by attaching a top sealing member across the top opening. The top sealing member is attached by welding a peripheral flange of the top sealing member to the inner surface of the tubular body. As disclosed herein, the top sealing member is commonly a flexible component made from a laminate of one or more layers of aluminium foil and outer layers of thermoplastic polymeric material and the peripheral flange is created by folding an edge portion of the top sealing member out of the plane of the top sealing member and into alignment with the inner surface of the tubular body. The top sealing member is taken from a magazine which is not visible in
[0198] The intermediate can with the applied top sealing member is then transferred to the top rim application station 14 where the top rim is applied to the intermediate can by inserting at least a lower part of the top rim into the top opening, above the top sealing member. Preferably, the top rim is inserted into the tubular body such that an upper end edge of the top rim remains outside of the tubular body or is flush with the top end edge of the tubular body whereby the top rim protects the vulnerable carton edge of the tubular body and forms a rigid resting surface for the intermediate can during the subsequent process steps.
[0199] As illustrated in
[0200] After application of the top rim and turning the intermediate can upside down, the intermediate can is transferred to a first conveyor 2a and placed with the top rim resting on the conveyor 2a and a bottom opening at a bottom end of the tubular body facing upward in the vertical direction. The intermediate can is moved by the conveyor 2a to the filling unit 4 where it is filled with dry or moist goods through the bottom opening of the tubular body.
[0201] Subsequently, while still resting on the top rim, the filled intermediate can is moved by a second conveyor 2b to the gas box 5 where the filled intermediate can is subjected to treatment by a protective gas while the intermediate can is moved through the gas box 5. The gas box 5 is an optional part of the process equipment for carrying out the method as disclosed herein which may be used e.g. when the packaged goods is sensitive to oxygen and/or moisture. Furthermore, creating a protective gas atmosphere for the filled intermediate can may be made by other means, as set out herein. After leaving the gas box 5, the filled intermediate can is transferred to the sealing unit 6 on a third conveyor 2c. The third conveyor 2c moves through a gas tunnel which is tightly fitted to the wall of the sealing unit 6 at the inlet into the sealing unit 6, in order to maintain the protective atmosphere created in the gas box 5.
[0202] In the sealing unit 6, the bottom opening of the tubular body is sealed in a can sealing station 21 by attaching a bottom sealing member across the bottom opening, the attachment being made by welding a peripheral flange of the bottom sealing member to the inner surface of the tubular body at a distance from a bottom end edge of the tubular body. Accordingly, the bottom sealing member is applied in a manner corresponding to that of the top sealing member by folding a peripheral edge portion of the bottom sealing member into alignment with the inside wall of the tubular body before welding the facing surfaces of the bottom sealing member and the tubular body to each other. The sealing unit 6 preferably comprises a rim application station 22 for application of a bottom rim after the bottom sealing member has been inserted in the tubular body and welded in place. As disclosed herein, application of a bottom rim is an optional operation which may be performed on the intermediate can.
[0203] As is seen in
[0204] After filling, bottom sealing, and optional application of a bottom rim, the intermediate can is again turned to bring the top rim in an upward-facing position in the vertical direction.
[0205] In analogy with the first turning operation which is carried out after application of the top rim, the can turning arrangement may be part of the sealing unit 6 so that the intermediate can is turned directly after bottom sealing and optional bottom rim application. In the assembly line 1 which is shown in
[0206] In the example shown in
[0207] As set out herein, a scoop or other item may be placed above the top sealing member before finally closing the composite can by attaching the lid. As shown in
[0208] The filled and sealed intermediate can is thereafter transported to the lid attachment unit 7 on the conveyor 2d and a reclosable lid is attached at the top end of the tubular body such that an inner surface of the reclosable lid is in direct contact with an upper surface of the top rim. As set out herein, the reclosable lid may be applied as part of a lid component, the lid component further comprising a frame structure. Preferably, the lid component is mechanically attached to the upper rim by a snap-fit connection.
[0209] The assembly line may further comprise quality control equipment and equipment for removing deficient intermediate composite cans and fully assembled composite cans from the flow of composite cans. Such quality control equipment may comprise detection equipment for detecting flaws in the intermediate cans or machine malfunctioning during production e.g visual detection devices, an X-ray machine which may be placed after the lid attachment unit 7, etc. Furthermore, the quality control equipment may comprise can rejection stations which are commonly placed after one or more of the body forming unit 3, the filling unit 4, the sealing unit 6, the scoop insertion unit 10 and the lid attachment unit 7 to ascertain that any deficient composite cans are removed from the production line.
[0210] As disclosed herein, the composite cans are filled with dry or moist goods in the form of particles or pieces, granules, flakes, grain, etc. The goods flows into the composite can under the influence of gravity.
[0211] The composite can 201 shown in
[0212] A bottom sealing member 215 is positioned at the bottom end of the tubular body 203 and covers the bottom opening 213. The tubular body 203 has been formed by bringing together the side edges of a body blank end-to-end and sealing the join with a sealing strip 214, as set out herein.
[0213] The bottom end edge 207 is reinforced by a reinforcing bottom rim 217 which is applied to the inner surface of the body wall 205 and/or to a peripheral flange 216 of the bottom sealing member 215, between the bottom sealing member 215 and the bottom end edge 207. In the illustrated embodiment, the bottom rim 217 has an outwardly directed flange 219 which covers the bottom end edge 207 of the tubular body 203 and forms a bottom edge of the can 201. The bottom rim 217 reinforces the bottom end edge 207, stabilizes the shape of the tubular body 203 and protects the bottom edge 207 from mechanical deformation. The bottom rim 217 also serves as a protective barrier against water and other fluids which may be present on a surface on which the can 201 is placed. The bottom rim 217 delimits a downwardly open space between the bottom sealing member 215 and the bottom edge of the can 201, which may be used to accommodate stacking elements arranged at an upper end of another can when stacking two or more cans on top of each other. The reinforcing bottom rim 217 is an optional component of the composite can as disclosed herein.
[0214] As an alternative to the illustrated bottom rim 217, the bottom edge of the composite can 201 may be formed by a rolled edge of the tubular body 203, or may be provided by a simple, non-rolled join between the bottom sealing member 215 and the tubular body 203.
[0215] The composite can 201 is provided with a closure arrangement comprising a lid 221 and a top rim 223 extending along the edge of the top opening 211. The lid 221 comprises a planar inner sealing disc 225 which seals against the top rim 223 when the composite can 201 is closed, as shown in
[0216] The bottom rim 217 and the top rim 223 are made of plastic material, preferably thermoplastic material and form closed loops, as seen in
[0217] The top rim 223 defines a perimeter of an access opening which is smaller than the upper container body opening 211 as defined by the upper end edge 209 of the tubular body 203.
[0218] As set out herein, the top rim 223 is attached to an inner surface of the body wall 205 at the top opening 211. The top rim 223 has an extension in the height direction, H, of the composite can 201 and has a lower rim part facing towards the bottom sealing member 215 and an upper rim part facing away from the bottom sealing member 215. The top rim 223 extends around the full periphery of the top opening 211. The upper part of the top rim 223 protrudes upwards in the height direction, H, above the top end edge 209, whereby a part of the top rim 223 is arranged above the top end edge 209 in the height direction, H, of the composite can 201.
[0219] The top rim 223 is joined to the inner surface of the body wall 205 by means of a weld seal extending around the top opening 211. The weld seal preferably extends continuously around the top opening 211 and is a sift-proof weld seal and is preferably also a moisture proof weld seal and most preferably a gas-tight weld seal.
[0220] As set out herein, the weld seal between the top rim 223 and the body wall 205 is formed by supplying energy to heat and locally soften or melt one or more thermoplastic component in the top rim 223 and/or in a coating or film on the inner surface of the body wall 205 and by pressing the top rim 223 and the body wall 205 together in a direction perpendicular to the body wall 205. The temperature and pressure can be controlled and adjusted to form a strong and tight seal without damaging the welded components. The thermoplastic material used to create the weld seal may be provided by a fully or partly thermoplastic top rim 223, by a thermoplastic film or coating on the inner surface of the body wall 205, or by thermoplastic material from both the top rim 223 and the body wall 205. The top rim 223 is preferably made from thermoplastic material which allows it to be thermoformed, e.g. by injection molding. An injection molding process may be used to form plastic components having different polymer compositions in different parts of the plastic component. By way of example, the surface of a plastic top or bottom rim which is to be welded to the container body may be formed from a polymer composition having a lower softening and melting point than other parts of the rim. Moreover, an abutment surface on the top rim 223 may be formed from a resilient thermoplastic polymer. Any suitable welding technique may be used, such as ultrasonic welding or high frequency induction welding, with high frequency induction welding being preferred, as set out herein.
[0221] The lid 221 is a profiled part with a three-dimensional shape providing an upper outer surface of the lid 221. The lid may have an inner surface comprising a pattern of reinforcing ribs. The composite can shown in
[0222] The lid 221 is connected by a hinge 229 to a frame structure 230, the lid 221 and the frame structure 230 together forming a lid component 231. The hinge 229 is a live hinge, formed integrally with the lid 221 and the frame structure 230 as a flexible connection between the lid 221 and the frame structure 230. As set out herein, the illustrated hinge is only intended as a non-limiting example and it should be understood that any other type of functional hinge may be used for a connection between the frame structure and the lid.
[0223] Moreover, the lid may be of the removable kind, without any permanent connection to the frame structure.
[0224] The frame structure 230 is applied to the composite can 201 at the top end edge 209 and is mechanically attached to the top rim 223 by a snap-on connection. The frame structure 230 is attached to the top rim 223 after the top rim 223 has been welded to the inner surface of the body wall 205. The frame structure 230 is applied to the top rim 223 by pressing the frame structure 230 down over the upper edge of the top rim 223 until the frame structure 230 locks in place on the top rim 223 by means of mating snap-in features on the top rim 223 and the frame structure 230. When the frame structure 230 has been attached to the top rim 223, it can only be removed again by breaking or damaging the snap-in connection between the top rim 223 and the frame structure 230.
[0225] An interior compartment 208 containing the packaged goods is delimited by the top sealing member 227 at the upper end of the tubular body 203 and by the bottom sealing member 215 at the bottom end of the tubular body 203.
[0226] In order to gain a first access to the packaged goods in the interior compartment 208, a user needs to open the lid 221 and expose the packaged goods by fully or partly removing the top sealing member 227. The top sealing member 227 may be arranged to be peeled away from the wall 205 of the tubular body 203 or may be arranged with means for breaking the top sealing member 227 so that it can be at least partly removed through the access opening. Such means may be in the form of one or more predefined weakenings, such as perforations or a cut partly through the top sealing member 227. When the top sealing member 227 is of the tear-open type, a narrow edge part of the top sealing member 227 may be left at the inner surface of the body wall 205. Any such remaining part of the top sealing member 227 should preferably not be so large so that it extends into and restricts the access opening which is defined by the inner perimeter of the top rim 223.
[0227] Once the top sealing member 227 has been removed, it is sufficient to open the lid 221 in order to gain access to the packaged goods in the interior compartment 208 through the access opening. As is seen in
[0228] When the composite can 201 is open, a desired quantity of the packaged goods may be removed from the composite can 201 through the access opening either by means of a scoop or by pouring. The scoop may preferably be provided together with the composite can 201. The scoop may initially be placed on the top sealing member 227, may be removably attached to the inner surface of the lid 221 which inner surface is constituted by the sealing disc 225 in the example shown in
[0229] Advantageously the scoop head 281 has a tapering shape to allow she scoops 280 to fit snugly inside each other in an efficient and space saving manner.
[0230] As an alternative to stacking the scoops 280 with the scoop heads 281 and the scoop handles 282 arranged in the same direction, the scoops 280 may be stacked in alternating opposite directions as known in the art.
[0231] It is to be understood that the scoop 280 which is shown in
[0232] The closure arrangement as shown on the composite can 201 in
[0233] In order to keep the lid 221 secured in the closed position between dispensing occasions, the closure arrangement of the composite can 201 may further comprise a locking arrangement 245, as seen in
[0234] A locking arrangement 245 of this type is closed by moving the locking member 246 upward and inward over the lid 221 to a position where the locking elements come into mating engagement. The locking arrangement 245 is opened by pulling at the locking member 246 until the connection between the locking elements is released and turning the locking member 246 downward at the hinge 249. When the locking member 246 is in the closed position with the first and second locking elements engaging with each other, the lid 221 and the frame structure 230 are firmly clamped together whereby the top rim 223 seals tightly against the sealing disc 225 on the inner surface of the lid 221, or against a sealing ring or sealing surface arranged on the inside of the lid 221.
[0235] As best shown in
[0236] The lid component stacking step 251 is arranged to enable stacking lid components 231 on top of each other in stacks which can be loaded into a lid attachment unit. The can stacking step 252 is arranged for enabling stacking of composite cans 201 on top of each other.
[0237] An inset gripping area 265 may be arranged in the lid 221 at the free end portion of the locking member 246, opposite the hinge 249. Thereby, the locking member 246 can be easily accessed and while the locking member 246 when in the closed position is shielded from inadvertent release.
[0238] A composite can 201 as shown in
[0239] As set out herein, the composite cans as disclosed herein are produced in the following order: forming a tubular body, applying a top sealing member and a top rim to the tubular body, turning the tubular body upside down, filling the tubular body with dry or moist goods through the bottom opening of the tubular body, closing the bottom opening of the tubular body, optionally applying a bottom rim to the tubular body, turning the sealed can so that the top sealing member again faces upward and finally applying a lid or a lid component to the top end of the tubular body.
[0240]
[0241] With reference to
[0242] With reference to
[0243] Intermediate cans 403 are transported through the can sealing unit 401 in a running direction R. Transport means 402 comprising a feeding arrangement 411 in the form of two feed screw members arranged at respective opposite sides of the intermediate cans 403, whereof only one of the feed screw members is visible in
[0244] A can sealing station 405′ is located downstream of the feeding arrangement 411 and a bottom rim application station 405″ is located downstream of the can sealing station 405′. The movable gripping arrangement 415 move the intermediate cans 403 to the sealing station 405′ where bottom sealing members 427 are attached by welding to the inside of the tubular body wall of the intermediate cans 403, as illustrated by
[0245] The transport means 402 and the can sealing station 401 may be encased in an external housing 20, 23 as shown in
[0246] Degassing of the intermediate can may be performed concurrently with filling the intermediate can in a filling unit 4 as shown in
[0247]
[0248] An example of a transfer plate 529 is illustrated in
[0249] As an alternative, in particular when the can component is a sheet form can component such as a top sealing member or a bottom sealing member, the transfer plate 529 may be omitted such that the can component is placed directly on top of the retaining device 523.
[0250] In order to fit and hold the can component in the transfer cavity 533, the shape of the transfer cavity 533 is made to correspond to the shape of the can component.
[0251] In case of a can component including an edge portion which is to be folded to create a peripheral flange before or during insertion of the can component in the can, as is the case in a bottom sealing member or a top sealing member, the first open area A.sub.1 of the transfer cavity 533 may be smaller than the surface area of the can component before folding. The area difference corresponds to the area of the portion of the can component which forms the peripheral flange. Such a folded flange is typically band shaped and may have a width in the range of from 1 to 10 mm, such as in the range of from 2 to 5 mm. See
[0252] A wall of the transfer cavity 533 may comprise holding elements 534 adapted to hold the can component in the transfer cavity 533. See
[0253] In the embodiment illustrated in
[0254] As illustrated in
[0255] After application in the intermediate can 503, the sheet form can component covers the can opening and prevents gas from escaping out through the intermediate can 503. If the can component applicator is operated without a protective atmosphere or if some loss of protective gas can be tolerated, a transfer plate without a cover portion may be used when applying the can component. Furthermore, the attachment unit 505 may comprise an internal housing 547, as indicated by point-dashed lines in
[0256] In order to facilitate placing a can component into the transfer cavity 533 of the transfer plate 529, indentations 536 may be provided as illustrated in
[0257] If the can component is a sealing member, or a lid, the can component may instead be placed into the transfer cavity 533 by gripping means such as one or more suction cups. In such case, the indentations 536 may be omitted. However, suction cups are not suitable when the can component is of the loop type, such as a top or bottom rim.
[0258] In the illustrated embodiment, which may e.g. be a bottom rim application station 22 of an assembly line 1 as shown in
[0259] The retaining device 523 retains the intermediate can 503 while the can component, illustrated as the bottom rim 517, is being attached to the intermediate can 503. The retaining device 523 comprises at least one through-going positioning cavity 537 with a second open area A.sub.2 corresponding to the first open area A.sub.1 of the transfer cavity 533.
[0260] The positioning cavity 537 is adapted to receive a portion of the intermediate can 503. If having a cover portion 535, the size and shape of the cover portion 535 of the transfer plate 529 is selected, such that the cover portion 535 can be brought to cover, or at least substantially cover, the second open area A.sub.2 of the positioning cavity 537.
[0261] The supporting device 525 is arranged to support the intermediate can 503 and to position the intermediate can 503 in the retaining device 523.
[0262] The positioning device 528 is arranged to position the can component in the intermediate can 503 as illustrated by
[0263] In the illustrated embodiment the attachment unit 505 is arranged to simultaneously process four intermediate cans 503. The transfer plate 529 comprises four cavity portions 531 arranged in a row as seen in the first direction x of the attachment unit 505. In a corresponding way, the retaining device 523 comprises four positioning cavities 537, and the supporting device 525 is adapted to support four intermediate cans 503 and to position the intermediate cans 503 in the respective positioning cavities 537 of the retaining device 523. In addition, the attachment unit 505 comprises four positioning devices 528, aligned with the positioning cavities 537, such that each positioning device 528 is associated with a respective positioning cavity 537. It is to be understood that the attachment unit may be arranged for simultaneous processing of any suitable number of intermediate cans, as set out herein.
[0264] The transfer plate 529 is movable between a first position shown in
[0265] In the second position, as shown in
[0266] The retaining device 523 may comprise a welding unit 539 as disclosed herein. The welding unit is preferably a high frequency induction welding unit and is arranged around the positioning cavity 537. The welding unit 539 is adapted to weld the can component to the intermediate can 503, and comprises a coil extending around the positioning cavity 537. As the positioning device 528 may be caused to expand in a radial direction of the positioning cavity 537 as set out herein, the can component can be pressed against the welding unit 539.
[0267] As is shown in
[0268]
[0269]
[0270] The positioning device 828 comprises a base plate 849 comprising or being constituted by a rigid material such as metal or a composite material, and a plunger skirt 851 comprising a resiliently deformable material, e.g. rubber or plastics. The plunger skirt 851 is located on top of the base plate 849, such that it at least partly covers an upper surface of the base plate 849 which upper surface is opposite a lower footprint surface 853 of the base plate 849.
[0271] The footprint surface 853 is configured to face towards the can component, here a top sealing member 827, during application of the can component in the intermediate can 803. The footprint surface 853 of the base plate 849 has a circumferential edge 855 which in the illustrated example has a substantially polygonal shape. However, it is to be understood that the footprint surface may have any other suitable shape adapted to the cross-sectional shape of the composite can which is being produced. In the illustrated example, the substantially polygonal shape is a substantially square shape which comprises four side edge portions which are connected by outwardly rounded corner portions. In the illustrated embodiment, each side edge portion is slightly inwardly curved. Thereby, the circumferential edge 855 of the footprint surface 853 of the base plate 849 with the inwardly curved side edge portions deviates from the cross-sectional shape or footprint of the produced composite can. Alternatively, the base plate of the positioning device may have the same footprint as that of the intermediate can 803, with straight side edge portions between curved corner portions.
[0272] It may be advantageous to arrange a curved side edge portion at least on the side of the base plate 849 which during insertion of the can component will be facing the sealing strip 814 covering the join in the tubular body 805. The sealing strip 814 makes the tubular wall 805 of the intermediate can 803 locally thicker and also constitutes a bending line where the tubular wall 805 tends to bend causing the tubular wall 805 to deviate from a desired planar or near-planar shape. A slightly inwardly curved side edge portion of the circumferential edge of the footprint surface of the base plate, allows the base plate to move along the join without damaging the sealing strip or the can body material when the positioning device 828 inserts the can component 827 into the intermediate can 803.
[0273] The plunger skirt 851 is transformable between an unexpanded state and an expanded state by relative movement in relation to the base plate 849.
[0274] In the unexpanded state of the plunger skirt 851, the shape of the outer contour of the plunger skirt 851 corresponds to that of the base plate 849. Hence, in the unexpanded state, the plunger skirt 851 has the same or substantially the same footprint as the base plate 849.
[0275] When seen in relation to the base plate 849, the outer circumference 861 of the plunger skirt 851 is located at or on the circumferential edge 855 of the base plate 849. Preferably, the outer circumference 861 of the plunger skirt 851 coincides with the circumferential edge 855 of the footprint surface 853 of the base plate 849 or is located slightly inside the circumferential edge 855 of the footprint surface 853 of the base plate 849 when the plunger skirt 851 is in the unexpanded state.
[0276] In the expanded state of the plunger skirt 851, the footprint which is delimited by the outer circumference 861 of the plunger skirt 851 is larger than in the unexpanded state of the plunger skirt 851.
[0277] During transformation to the expanded state, pressure is applied to the plunger skirt 851 from above. Thereby, the side edge portions of the plunger skirt 851 are stretched between the corners and any curved side edge portion is thereby straightened out. By selecting the shape and material properties of the plunger skirt 851, a desired change of shape during transformation may be obtained.
[0278] In the expanded state of the plunger skirt 851, the outer circumference 861 of the plunger skirt 851 is located at least partly outside of the corresponding circumferential edge 855 of the base plate 849. By transforming the plunger skirt 851 to the expanded state, it may be brought into contact with an edge portion 833 of the top sealing member 827 and be caused to press the edge portion 833 of the top sealing member 827 against the inside of the body wall 805.
[0279] If the can component attachment unit is provided with a transfer plate 529 comprising holding elements 534 as disclosed herein exerting an inwardly directed force on the can component, the plunger skirt 851 may contribute to press the can component back in a radial direction in case the can component does not spring back sufficiently itself from a deformed configuration imparted on the can component by the holding elements 534.
[0280] The positioning unit shown in
[0281] During displacement of the positioning device 828 into the intermediate can 803, the plunger skirt 851 remains in the unexpanded state until the can component 827 has been moved to the attachment position. When the can component 827 has reached the attachment position, the plunger skirt 851 is transformed to the expanded state by moving the end portion of the second piston 873 closer to the end portion of the first piston 871 thereby pressing an edge portion of the plunger skirt 851 radially outward.
[0282] The outer circumference 861 of the plunger skirt 851 presses the can component 827 against the inside of the body wall 805 of the intermediate can 803 which is placed in the positioning cavity. The edge portion of the outer circumference of the plunger skirt 851 which in the expanded state of the plunger skirt 851 is arranged to be in contact with and exert pressure on the can component, may have a contact surface which in the non-expanded state of the plunger skirt is slightly tilted with respect to the vertical direction of the positioning device.
[0283] In order to further improve contact between the can component and the can body material in the corner portions, thickened corner portions may be arranged on the upper surface of the base plate, i.e. on the surface opposite the footprint surface of the base plate. The thickened corner portions form raised areas on the upper surface of the base plate and serve to force the plunger skirt to move further out, exerting an increased pressure on the applied can component and improving contact between the can component and the tubular body. Thereby, a join formed between the can component and the corner portions of the tubular can body may be improved. In particular, an increased pressure in the corner portions of the tubular body may aid in creating a tight seal between the body material and a sheet form can component. Excess material present at the corner portions of sheet form can components, such as a bottom sealing member or a top sealing member, will generally wrinkle at the corners of the can as the can component is folded and aligned with the tubular body wall. In such case, an increased pressure created at the corner portions of the tubular body would compress the wrinkles and would contribute to the formation of a good functional bond, such as a thermo-weld between the body material and the sheet material in the can component. When using a thermo-welding process for bonding the can component to the wall of the tubular can body, at least one and preferably both of the can component and the tubular wall comprise a thermoplastic material in a sufficient amount to create a functional bond.