GB2504286A

GB2504286A - Collar for the Alignment of Large Mouth Containers for Induction Welding

Info

Publication number: GB2504286A
Application number: GB1213112.4A
Authority: GB
Inventors: Peter Michael Mcgeough; Derek Fergus Shepherd
Original assignee: Bapco Closures Research Ltd
Current assignee: Bapco Closures Research Ltd
Priority date: 2012-07-24
Filing date: 2012-07-24
Publication date: 2014-01-29
Anticipated expiration: 2032-07-24
Also published as: WO2014016558A1; GB2504286B; GB201213112D0

Abstract

An aligment collar 30 which is adapted to surround a package comprising a container body and a pre-foiled closure and align the two parts together has expandable bellows inserts (50, fig 2) in opposing wall portions in order to expand once the collar is in position to centralise the closure over a rim of the neck formation in order to avoid creating leakers. Connectors 54 to supply / withdraw gas from the inserts are provided in the collar. The expandable inserts are preferably sealed tubes received within a bore in the wall of the collar and may be pinched by means of restraining pins. Preferably, a smooth, non-stick surface may cover the expandable inserts. A control system may be used to inflate and deflate the inserts in synchronism to complete the alignment process.

Description

Collar for the Alignment of Large Mouth Containers for Inducflon Welding

Technical Field

[0001] The present invention relates to the alignment of containers with closures on a packaging conveyor line and, more particularly, to such an alignment system adapted for use with a non-contact induction heat sealing method using a laminated induction heat sealing foil such as described in WO 99/61 337 A (SPRECKELSEN MCGEOUGH LTD) 12.02.1999 (BAF ® technology). It is particularly suitable for use with large mouth containers but is not limited to such containers.

Background Art

[0002] When induction welding using BAF® technology, filled containers are moved along a conveyor and pre4oiled closures, which include a spout intended to be fixed to the container and a removable cover, are positioned over the open mouths of the containers. A shroud or collar is then positioned over the closure to locate a sealing flange of the closure in the correct position centrally over a neck finish of the container to ensure that a rim of the neck finish is welded to the foil beneath a portion of the sealing flange of the spout that is designed for that purpose, rather than to a removable part. Once the parts are aligned, an induction coil is actuated to create the weld. If the weld is made incorrectly it may be difficult or impossible to open the container if the removable part is held too firmly in position, or there may be gaps in the weld to the closure that will result in leakage.

[0003] Existing collars are made of a rigid, non-conductive material. They have a lower face with a tapering opening so that a closure is slid or nudged into a central position over a neck finish of the container.

[0004] Typically, the container will be made of a relatively flexible material such as polyethylene in order to make the container as lightweight as possible.

The tolerance of the mouth dimensions in the container is relatively much greater than the tolerance of the dimensions of the closure, which is typically injection moulded and more accurately manufactured. The collar must be capable of shifting the container relative to the closure (or vice versa) by a distance equivalent to at least the combined tolerances of the container neck finish and closure. This presents a first technical problem.

[0005] When excessive top load pressure is applied to a container with a large open mouth, particularly a rectangular mouthed container, this can result in bowing of the longer sides ("dog boning"). Such deformation of the shape of the container mouth will result in an imperfect weld and the container will then leak. Accurate welding is therefore necessary to avoid a significant proportion of "leakers" which disrupt the supply chain. An advantage of the BAP® technology is that minimal top load pressure is needed. It is simply necessary to maintain the parts in contact during the welding operation. However alignment collars that need to create a substantial lateral movement may need to be forced onto the closure with sufficient pressure to cause deformation problems. This presents a second technical problem.

Disclosure of Invention

[0006] The alignment collar of the invention is designed to solve the above identified technical problems.

[0007] An alignment collar comprises a sleeve of nonconductive material adapted to be placed onto and surround a pre-foiled closure when seated over a neck finish of a container body on a production line in order to align a sealing flange of the closure relative to the neck finish, the collar comprising a wall extending from a lower face with an opening larger than either the closure or container, the wall having a first internal wall section adapted to seat adjacent the neck finish of a container to be welded, a tapered wall section inclined inwardly from the opening and merging with the first internal wall section, a second internal wall section above the first internal wall section adapted to surround an upper part of the closure and to support an induction coil at a correct spacing from an intended weld location, characterised in that opposed expandable inserts are located within opposing portions of the wall and are exposed in the first internal wall section; and in that the collar further comprises connectors to supply a gas to andlor withdraw the gas from each expandable insert in synchronism in order to complete the alignment process begun when the collar was placed over the assembled closure and container.

[0008] Other preferable features of the collar are set out in the claims.

Advantaaeous Effects [0009] The use of the expandable inserts allows a second stage of alignment between the closure and the container to take place once the collar is in position. The system is particularly advantageous with containers with large rectangular open mouths such as used for powder products, has the equal and opposite pressure on the narrower sides of the container counteracts the top load pressure applied by the induction coil and prevents the longer sides of the rim of the container from moving inwardly.

[0010] When used with containers of other mouth shapes, the expandable inserts can be circumferentially located or on any pair of products facing surfaces including corners.

Brief Description of Drawings

[0011] An embodiment of the invention will now be described, by way of example only, with reference the accompanying diagrammatic drawings, in which: [0012] Figure 1 is a perspective view of a collar in accordance with the invention; [0013] Figure 2 is a detailed view of an expandable insert showing how it is mounted within the collar; [0014] Figure 3 is a partially broken away view of the inside of the collar showing how the expandable insert can be protected by a smooth web; and [0015] Figure 4 shows a diagrammatic view of a production line showing the sequence of events on a conveyor belt during the container sealing operation.

Mode(s) for Carrying Out the Invention [0016] The embodiment described relates to sealing closures on rectangular -mouthed, extrusion blow moulded containers such as might be used for baby milk powder as illustrated diagrammatically in Figure 4. It will be appreciated that the collar can be adapted to various configurations and geometry of neck finish.

[0017] A container body 2 has a neck finish 4 that terminates in a rim 6 at an open mouth of the container. The container bodies are to be filled and then sealed with a pie-foiled closure 10 which comprises a spout and an openable cover 12 hinged to the spout. A detailed description of a suitable closure can be found in WO 2011/067585 A (BAPCO CLOSURES RESEARCH LIMITED) 09.06.2011 the disclosure of which is incorporated herein by reference. The closure spouts have a base in the form of a flange to which a laminated or cast induction heat sealing foil has been welded. The foiled flange is designed to rest on the rim 6 of the container body and be welded in position. As the filled bodies move along a conveyor belt 20, the closures 10 are positioned on the containers and then a collar 30 in accordance with the invention is placed over the top of the closure in order to align the flange centrally over the rim. This may require a significant degree of sliding motion, particularly in a situation where a container body which has dimensions at the lower end of the tolerance range is mated with a closure which has dimensions at the upper end of its tolerance range. While the width of the flange is designed to cope with the design tolerances, it is still necessary to ensure that the flange is correctly positioned. As shown in Figure 4, once the alignment step has been made by covering the closure with a collar, an induction head 150 is brought into position to complete the weld in a now conventional manner. In an alternative design, the induction coil and collar can be created as one assembly actuated by an individual mechanism.

[0018] The collar 30 will now be described in more detail with reference to Figures 1 to 3. The collar is essentially a sleeve of nonconductive material having a rectangular profile with two opposing shorter wall portions 28 joined by two longer wall portions 26 surrounding a headspace capable of fitting over the closure and resting around the neck formation. The collar has a lower face 32 with an opening 34 larger than a profile of either component (closure or container) of the package so that it can be readily dropped into position over an assembled but unsealed package on the conveyor belt 20. An internal wall of the collar has a tapered section 36

S

adjacent the opening which initiates the alignment process by bringing the closure into the centre of the collar. The tapered section 36 merges with a first internal wall section 38 adapted to seat adjacent the neck finish of the container to be welded, in use. The first section 38 is separated from a slightly larger second internal wall section 40 above it by a horizontal ledge 42 which, in use, will lie at the level of the sealing flange where a weld is to be made. An upper surface 44 of the collar is flat.

[0019] Cylindrical bores are created within the material of the shorter wall portions 26 in order to receive respective expandable inserts 50 or bellows. The bores are created so that they open into the first internal wall section at an elongate window 52 which allows the insert to engage with an adjacent neck formation when the collar is in use and in position on a package.

Non-metallic connectors 54 are provided at one end of each of the expandable inserts to allow the inserts to be connected by means of flexible hoses 55 to a pump which will be controlled in order to cycle through a sequence of operations in which gas is supplied to the inserts in synchronism to expand them and then a vacuum is applied to the inserts to suck out the gas and allow the inserts to retract out of the space within the collar in the manner of a pair of bellows.

[0020] As shown in Figure 2, the expandable insert 50 is preferably a silicone tube which has had its remote end sealed with a disk of the same material.

The material of the insert must be suitable for use in the food industry and be flexible so that it can undergo the repeated cycling of inflation and deflation in order to expand and contract it in operation. Plastic materials with rubberlike characteristics are also suitable. The tube is supported within the body of the wall portion 28 by means of restraining pins 56 which are provided in pairs and positioned laterally beyond the extremities of the window 52 in order to pinch the adjacent ends of the tube. The pins hold each end of the expandable insert along a central axis of the tube so that, as the insert inflates and deflates, it tends to fall back towards the central axis, rather than buckling and protruding from the window, which could prevent easy removal of the collar.

[0021] Because the expandable insert or bellows can be slightly tacky and may become engaged with the neck formation, the window is preferably loosely covered with a PTFE coated fibreglass tape 58 which can be readily clamped in position by having its ends secured in a recess 60 on both upper and inner horizontal surfaces of the horizontal ledge 42 and the upper surface 44 of the collar 30. When the expandable insert 50 is inflated it projects through the window but it is the smooth surface of the tape which engages with the neck formation in order to urge it gently into the desired central location relative to the closure. The bellows insert itself may be coated with PTFE or otherwise made smooth.

[0022] A control mechanism 62 is provided to control the supply of gas, preferably compressed air, to the two connectors 54 of each collar in synchronism so that the inserts 50 inflate simultaneously acting in the same manner as a pair of hands gently shuffling the container body into the desired central position. One cycle of expansion and deflation during alignment may be sufficient but multiple expansions could be used if necessary.

[0023] The alignment by use of the collar is completed before the induction head is brought down to rest on a top of the collar to complete the welding process. The expandable inserts are kept expanded during the induction sealing so that the side walls of the neck formation are under pressure so as to prevent the longer walls deforming inwardly. Once the weld has been completed, the induction head and collar are removed and the sealed packages can move away on the conveyor belt for the next stage of processing.

[0024] The collar need to be made of a hard, dimensionally stable material, and must not interfere with the magnetic field of the induction head. A suitable material is the plastic, polyoxymethylene, sold as DELRI NI®.

[0025] When used with a non-rectangular container, the inserts will still need to be located in opposing pairs. In the case of a circular neck, the inserts may extend circumferentially and be diametrically opposed. In other configurations, the inserts may face other surfaces including corners. In other geometries, it may be necessary to provide more than one pair of inserts.

Claims

Claims 1. An alignment collar (30) comprises a sleeve of nonconductive material adapted to be placed onto and surround a pre-foiled closure (10) when seated over a neck finish of a container body on a production line in order to align a sealing flange of the closure relative to the neck finish, the collar comprising a wall (26, 28) extending from a lower face (32) with an opening (34) larger than either the closure or container, the wall having a first internal wall section (38) adapted to seat adjacent the neck finish of a container to be welded, a tapered wall section (36) inclined inwardly from the opening and merging with the first internal wall section, a second internal wall section (40) above the first internal wall section adapted to surround an upper part of the closure and to support an induction coil (150) at a correct spacing from an intended weld location, characterised in that opposed expandable inserts (50) are located within opposing portions (26) of the wall and are exposed in the first internal wall section; and in that the collar further comprises connectors (54) to supply a gas to and/or withdraw the gas from each expandable insert in synchronism in order to complete the alignment process begun when the collar was placed over the assembled closure and container.
2. A collar as claimed in claim 1, wherein the expandable inserts are sealed tubes received within a bore in the wall which opens into the space within the sleeve at an elongate window.
3. A collar as claimed in claim 2, wherein each end of the tube (50) is pinched towards a central axis of the tube by means of restraining pins (56) within the wall.
4. A collar as claimed in claim 1, wherein the expandable inserts are covered by a smooth surface.
5. A collar as claimed in any one of the preceding claims in conjunction with a control system to inflate and deflate the inserts in synchronism.