WO2013152984A1

WO2013152984A1 - Edge cleaner

Info

Publication number: WO2013152984A1
Application number: PCT/EP2013/057096
Authority: WO
Inventors: Mats Martinsson; Johan Persson; Stefan Bengtsson; Holger SCHARF
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2012-04-10
Filing date: 2013-04-04
Publication date: 2013-10-17

Abstract

An edge cleaner (100) comprises a longitudinal groove (110) having a width for accommodation of an edge portion of the web passing through the longitudinal groove; at least one gas evacuation opening for evacuation of gas (116), and orifices for ejecting one or more air streams towards the edge portion (124, 126), on either side thereof, in the direction of the gas evacuation opening.

Description

EDGE CLEANER

TECHNICAL FIELD

The present invention relates to an apparatus removing dust from an edge region of a web of packaging material.

BACKGROUND

Some background for the present invention may be found in WO2011/139219 by the present applicant. The purpose of the device of the cited application is not identical to the basic purpose of the present application; while the former relates to dust removal in connection with guiding of a packaging-material web, the present application relates mainly to dust removal only. A document which may be considered more relevant in that respect is EP 1674398, also by the present applicant.

Within the field of packaging food products, and in particular packaging such products under aseptic conditions use is often made of sterilized packaging containers, such as Tetra Brik Aseptic (registered trademark). Tetra Brik Aseptic, as well as similar packages, may be manufactured by forming and sealing a strip-rolled packaging material. The packaging material comprises a layer of fibrous material, such as paper, sandwiched between two or more layers of thermoplastic, such as polyethylene. The side of the packaging material to be contacted by product may also comprise a barrier material layer, such as an aluminium layer, which in turn is covered by a layer of thermoplastic material.

In a typical packaging process the packaging material is sterilized, whereafter the two longitudinal edges of the packaging material are joined such as to form a continuous tube. The tube of packaging material is filled with product, usually sterilized product, whereafter the tube is provided with transversal seals such as to form pillow-shaped packages that may be severed from the continuous tube and folded into individual packaging containers.

Instead of using a tube of packaging material the material web may be cut into blanks in a first step, whereafter the blanks are folded into packaging containers, with or without addition of opening devices or similar packaging portions. When forming packaging containers from blanks the packaging material is generally not sterilized in advance.

Examples include packaging concepts where a filling machine is fed with packaging blanks (such as often is the case for carton gable top type packages) and concepts where a filling machine is fed with a roll of packaging material which subsequently is cut into blanks within the constraints of the filling machine)

The present invention is particularly well-suited for the described type of packaging material, and also for situations where the packaging material is used for production of packages in which high level of sterilization is required. Dust and debris of various types may provide grow sites for microorganisms, and it may also block a sterilization agent from reaching its intended goal, e.g. dust deposited on the surface of some packaging material may prevent a sterilisation agent from acting on the surface. Dust generation may also be a problem if the dust is accumulated at a particular location in a machine and causes mechanical problems.

In an otherwise clean environment the major source of dust is the raw edge of the packaging laminate, i.e. the narrow edge along which the fibrous paper core is exposed. The capacity of filling machines, counted by number of containers per hour, in which the packaging material may be processed (cut, folded, filled, sealed) is very high, in the order of 10 000 packages per hour and more. This results in that a seemingly insignificant rate of dust generation may become an issue that has to be dealt with. Therefore, in most applications where a web of material is handled on an industrial scale, there is a dust removal system of some kind installed. The dust removal system may remove the dust in the free air, by circulating it through a filter, yet it may also be designed to remove dust from surfaces and edges or a combination of the three. The dust removal may be remote (contact- free), using vacuum combined with air streams, or based on contact between the web material and a brush or a similar arrangement.

The present invention relates to a dust removal system which actively removes dust from an edge of a packaging material web.

SUMMARY

The dust removal system of the present invention will be called edge cleaner in the following, since in the preferred embodiment it has the dedicated purpose of actively cleaning the edge of the web material. In this context it may as well be emphasized that the dust referred to may comprise fibre residues or other particulate matter, and should not be construed as limited to one or the other. In that respect the present invention relates to an edge cleaner for actively removing debris from an edge portion of a web of packaging material, preferably packaging material comprising laminated material with a fibre core sandwiched between non- fibrous layers such as polyethylene, PP, possibly metal foil, comprising:

a longitudinal groove for accommodation of an edge portion of the web passing through the longitudinal groove,

at least one gas evacuation opening for evacuation of gas at a bottom of the longitudinal groove, and

orifices for ejecting one or more air streams towards the edge portion, on either side thereof, in the direction of the gas evacuation opening and the bottom of the groove.

The longitudinal direction corresponds to a travel direction of the web passing through the edge cleaner, which in turn corresponds to the longitudinal direction of the web itself.

The edge portion may be defined as a comprising (a portion of) the longitudinal edge of the web and an area of the web adjacent to the edge, i.e. the portion where a major part of the dust is found. It is to be understood that the edge cleaner is static during operation while the web passes through the edge cleaner at a certain speed.

In one or more embodiments the groove has parallel lateral side walls, and it is preferred that the groove has an overall U-shape, with the evacuation opening arranged at the bottom of the U-shape.

In one or more embodiments it is preferred that the lateral side walls of the groove each have an open-ended indentation in the region adjacent to the evacuation opening, such that the indentation opens up towards the evacuation opening.

It is preferred that the depth of the indentation increases towards the evacuation opening, such that the indentations of opposing lateral side walls of the groove forms a cavity having its largest opening towards the evacuation opening. The width of the groove will define the opening of the cavity in all other directions, as will be evident from the detailed description.

In one or more embodiments the orifices for ejecting air are arranged in the lateral sidewalls of the groove, wherein supply channels may be arranged inside the same sidewalls. In one such embodiment the orifices are formed by openings in the cavity formed by the combined indentations, and in one or more related embodiments the stream of air is ejected normal to the surface in which the opening is arranged.

In one or more embodiments the indentation follows an inclined path in the direction of the evacuation opening, resulting in an overall V-shape when observing the cross section of the cavity formed by the combined indentations. In one or more related embodiments the inclination of the surfaces where the ejection orifices are arranged is about 30° relative to the plane of the web passing through the groove (i.e. relative to the lateral side walls of the groove) .

The cavity preferably has a longitudinal extension corresponding to the extension of the evacuation opening in the same direction, or less, to better avoid the formation of ledges where particle build-up could occur (which would be the case if the longitudinal direction of the cavity was smaller than the evacuation opening.

In one or more embodiments the orifices for ejection of air may be symmetrically arranged in pairs with one orifice on either side of the web, and in related embodiments there are two, three, four or more such pairs.

In one or more embodiments the evacuation rate through the evacuation opening exceeds the combined ejection rate through the orifices, counted on total mass flow. In one or more embodiment the ratio is 2: 1 or more, such between 2: 1 and 20: 1, e.g. about 15: 1 or about 3: 1.

The averaged ejected flow of air may in one or several embodiments be directed towards the edge of the web. In a related embodiment the ejected flow of air is arranged to impact the web with its main flow. In other embodiments where more than one pair of orifices are used, on first pair may be arranged to impact with a major part of its mass flow onto the web, on either side thereof, and a second pair may be arranged to impact with a minor part of its mass flow onto the web (the remaining part passing outside the edge to be cleaned). With the latter approach at least two effects are achieved: The performance of the system will not be as sensitive to slight movements of the web in the axial direction, which may occur during operation, and the first pair will generate a flow directed straight into the evacuation opening (as it is redirected upon impact with the web), which will assist evacuation of dust freed by the combined action of the first and second pair. The first and second pair may be arranged along the same axial line on either side of the web. In one or more embodiments the groove is defined by three elements of the edge cleaner, two edge elements and one base. The edge elements may then comprise the ejection openings, and the base may comprise the evacuation opening. In one embodiment the edge elements are removably attached to the base portion, which facilitates cleaning of the device. In one or more related embodiments the edge elements are attached such that they may be readily removed for maintenance.

In one or more embodiments the air supplied via the orifices is preferably HEPA filtered air.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with reference to the accompanying, schematic Drawings which, for purposes of exemplification, show the currently preferred embodiments of the present invention according to both of its aspects. In the accompanying Drawings:

Fig. 1 is a perspective view of an edge cleaner in accordance with an embodiment of the present invention.

Fig. 2 is a detail view of an element of the edge cleaner of Fig. 1, in perspective.

Fig. 3 is a sectional view along line III-III of Fig. 1.

Fig. 4 is an exploded view of the edge cleaner of Fig. 1.

Fig. 5 is a sectional view similar to that of Fig. 3, showing a web arranged in the edge cleaner.

DETAILED DESCRIPTION OF EMBODIMENT

An embodiment of the present invention will now be described in detail. The general layout is presented referring to the perspective view of Fig. 1, in which an edge cleaner 100 is shown. The main components of the edge cleaner are the first side element 102, the second side element 104 and the base element 106. The first side element 102 will form a first lateral side wall of the groove and the second side element 104 will form the second lateral side wall, while the base element 106 will form the bottom of a groove 110 (to be described). These may be considered as separate functional elements even in a case where all or some of them would be formed in one piece. In the present embodiment, however, they constitute three separate elements which are releasably attached to eachother (the two side elements 102, 104 are attached to the base element 106). In an alternative solution the two side elements could be permanently attached to the base element by means of a weld or similar. The attachment and positioning of the first side element 102 may be effected by an attachment bolt 108 and a pin and hole arrangement (not visible in Fig. 1), and the attachment and positioning of the second side element 104 is effected by similar means not visible in Fig. 1. In the present embodiment the two side elements are shifted in a longitudinal direction. This is due to space issues and in other embodiments they may as well be arranged in a directly opposing relationship.

The two side elements 102, 104 are arranged in parallel, with a clearance therebetween, which in the following will be referred to as a groove 110, as previously mentioned. The direction of the groove 110 defines a longitudinal direction, which corresponds to the direction of movement of a web passing through the edge cleaner 100. This direction is downwards in the view of Fig. 1, and indicated by the arrow A in all drawings. In drawings where a direction is out of or into the plane of the drawing, a direction is indicated by the convention that a cross indicates a direction into the drawing and a point a direction out of the drawing. For the purposes of the present description an axial direction is defined as a direction orthogonal to the longitudinal direction, directed from the base element and towards and between the side elements (see arrow B). In an operational state this would correspond to a direction orthogonal to the edge of the web and in the plane defined by the web. The groove 110 is dimensioned to accommodate a web of packaging laminate. This means that the width of the groove exceeds the width (thickness) of the web by about 1-3 mm on either side thereof, generally giving the groove a width of about 3-7 mm. Depending on the thickness of the packaging material the width of the groove may vary beyond the exemplified limits.

Returning to the layout of Fig. 1 the edge cleaner further comprises supply conduits

112 and 114 for supplying air (or other gas) to the side elements 102, 104. An evacuation pipe 116 for evacuation of dust and air (or other gas) extends from the base element 106 through an evacuation opening 107 (see Fig. 4), the evacuation pipe 116 being in fluid communication with the groove 110 through cavities inside the base element 106. Bore channels (not shown, two per side element in the present embodiment) inside the side elements are used to direct the air from the supply conduits 112, 114 to the correct position, to be described later. Plug bolts 118, 120 seals one bore opening while the actual supply conduit coupling seals the other, and the two bores meet inside the side element. The components 146 and 154 will be discussed further, and they relate to components used for attachment of the second side element 104 to the base element 106.

The detailed view of Fig. 2 illustrates the second side element 104, from an angle not shown in the other drawings. A wedge-shaped indentation 122 is arranged in the lower portion of the side element 102. Together with an identical and opposing indentation of the second side element it will form a wedge shaped cavity having a cross sectional shape of an isosceles triangle with a top angle of about 60°. At least, this would have been the case had the first and second side element 102, 104 been arranged in contact, without the groove 110 as a clearance therebetween. The wedge-shaped indentations are mirror images of eachother, resulting in the above cross section. Ejection orifices 124, 126 are arranged for directing a flow of air (or other gas) towards an edge region of a web (in an operational state). The ejection orifices 124, 126 may be formed from straight bores extending from the inclined surface to the bore 128 (see Fig. 3) inside the side element 102. The orientation of the bore/orifice is preferably normal to the inclined surface 130, which may be better observed in Fig. 3. This arrangement vouches for excellent symmetry as the flow leaves the orifice. A lug 154 and its bore 156, which in the present embodiment is formed in one piece with the second side element 104, are part of an arrangement used for attaching the second side element 104 to the base element 106. There are obviously numerous other ways of attaching the second side element 104 to the base element 106, yet the present one provides an attachment which is readily accessible in an intended installation. In Fig. 2 it is also shown how the walls adjacent to the inclined surface 130 connects smoothly to the lateral side wall, following a radius.

The material of the present device is preferably durable, and examples include stainless steel and aluminium, while not excluding use of other materials, metals as well as plastics.

The evacuation pipe 116 and how it is connected to the base element 106 may also be seen in Fig. 3, as well as the fluid communication between the evacuation pipe 116 and the groove 110, and in particular the cavity/indentations of the lateral side walls. Though not self evident from Fig. 3 the evacuation pipe 116 is inserted into a circular bore of the base element 106 and an evacuation opening as such is defined by a bore machined in the base element 106. The effective size of the evacuation opening is defined where the cavity meets the evacuation opening, and it is preferred that the dimensions of the cavity are the smaller of the two (if they are not equally sized) such as to avoid ledges where material build-up may occur. In the interface area the cavity has a rectangular cross section, and the evacuation opening has a circular cross section. This is simply due to ease of manufacture, and in other embodiments the cross sections may vary without departing from the scope of the present invention as defined by the claims. In the cross section of Fig. 3 the inclination of the indentation surface of 30° is also clearly shown at a. Further it is clear that the previous statement that the cavity has the form of an isosceles triangle is a modified truth in that the top and base corners of the triangle are imaginary. Still, it is evident that in regard of the shape and configuration of the defining surfaces the statement is valid. The bores forming the ejection orifices 124, 126 and the arrangement thereof are also clearly seen. Only the orifices in the one side element 102 are shown, yet it is clearly seen that the other side element 104 comprises an identical set, in this embodiment, and that the orifices are symmetrically arranged. Extrapolating a bore centre axis reveals that the stream or flow from opposing orifices would intersect on the side of the interface area between the cavity and the evacuation opening facing the cavity. Also it is clear that a longitudinal direction of each bore is normal to the inclined surface of the cavity, such that the streams leave the cavity surface in the direction of the normal to the surface. The streams are arranged to impact on the edge of a web passing through the edge cleaner on different locations thereof. The first pair of orifices, orifice 124 and its counterpart is configured to intersect with at least a portion of its flow outside of the web edge, while the second pair of orifices, orifice 126 and its counterpart, are arranged to impact a bit further in to the web. In the illustrated embodiment a major part of the flow from the first pair of orifices will be located outside of the web edge. The flows will be balanced to be equal from each side in terms of mass flow rate and flow velocity. In one or more embodiments the total mass flow from the orifices may correspond to about 100 Nl/min while the flow through the evacuation opening corresponds to about 1500 Nl/min. In other embodiments the mass flow from the orifices may correspond to about 30-300 Nl/min while the flow through the evacuation opening may vary between about 400-4000 Nl/min. The two flows may vary beyond these limits, yet it is preferable that the evacuation flow exceeds the flow through the orifices by at least a factor 2 or more, preferably by a factor of 5 or more, and even more preferably by a factor of 10 or more. Some alternatives to the illustrated embodiment may be to alter the inclination of the cavity surface 30° to 60°, or any angle therebetween, such as 45°, and alter the orifices (bores) correspondingly. Further, the orifice configuration may be altered to comprise 3, 4, 5, 6 or more orifices on each side, preferably still symmetrically arranged though. It will still also be preferred that the arrangement of having some orifices directing an air flow onto and outside of the web edge and some orifices directing an airflow further into the web is maintained. It is conceivable that the airflow from different nozzles within a set differs, which is readily achieved by having different bore diameters for the different orifices. There are obviously more elaborate methods of solving a varying airflow too, yet there is not a need to discuss that in the present context.

Fig. 4 is an exploded view of the device of Fig. 1, showing some more details thereof. Like components have been given the same reference number as in Fig. 1 or in the other drawings, since they all relate to the same embodiment. Some components not visible in the other drawings will be mentioned in particular, and as for the rest reference is made to the previous description. For the first side element 102 we now see both the supply conduit 112 and its coupling 132, and the corresponding components (supply conduit 114 and coupling 134) are shown for the second side element. Returning to the first side element 102 the pin 136 and hole 138 configuration used to position the side element 102 is shown, and a corresponding arrangement (screw 140, pin 142, slot 148 for pin, and fitting 146 is shown) for the second side element is also shown. That arrangement is attached to the lug 154 and opening 156 (shown in Fig. 2).

Fig. 5 is a view almost identical to that of Fig. 3, yet a web 150 having an edge 152 has been indicated. Furthermore, some arrows and dotted lines have been added for visualization of the flow from the orifices towards the web 150 and web edge 152. To facilitate reading no other reference numerals have been added in Fig. 5.

Claims

1. An edge cleaner (100) comprising:

a longitudinal groove (110) defined by lateral sidewalls and a bottom, the groove (110) having a width dimensioned for accommodation of an edge portion of the web passing through the longitudinal groove,

at least one gas evacuation opening for evacuation of gas, and

orifices for ejecting one or more air streams towards the edge portion, on either side thereof, in the direction of the gas evacuation opening.

2. The edge cleaner of claim 1, wherein groove has parallel lateral sidewalls and a bottom, thus having an overall U-shape with the evacuation opening arranged at the bottom of the U-shape.

3. The edge cleaner of any preceding claim, wherein opposite sides of the groove each have an open-ended indentation in the region adjacent to the evacuation opening, such that the indentation opens up towards the evacuation opening.

4. The edge cleaner of claim 3, wherein the depth of the indentation increases towards the evacuation opening, such that the indentations of opposing side walls of the groove forms a cavity having its largest opening towards the evacuation opening.

5. The edge cleaner of claim 4, wherein the indentation follows an inclined path in the direction of the evacuation opening, resulting in an overall V-shape when observing the cross section of the cavity formed by the combined indentations, the inclined path being defined by an inclined surface (130).

6. The edge cleaner of claim 5, wherein an inclination of the indentation is between 10° and 60°, preferably about 30°, where 0° would correspond to no inclination and consequently no indentation relative to the groove.

7. The edge cleaner of any preceding claim, wherein the orifices for ejecting air are arranged in the lateral sidewalls of the groove.

8. The edge cleaner of any preceding claim 3-6, wherein the orifices are formed by openings in the cavity formed by the combined indentations, preferably by openings in the inclined surface (130).

9. The edge cleaner of claim 8, wherein the openings in the inclined surface extends as bores into the surface, the bore being normal to the surface such as to generate a flow normal to the inclined surface.

10. The edge cleaner of any preceding claim, wherein the orifices for ejection of air is symmetrically arranged in pairs with one orifice on either side of the groove, and wherein there are one, two, three, four or more such pairs.

11. The edge cleaner of claim 10, wherein the orifices of two pairs are arranged one above the other in a width direction of the web, and arranged such that, in use, the pair closest to the evacuation opening ejects air impacting with a minor part of its mass flow onto the web, from either side thereof, and the other pair ejects air impacting with a major part of its mass flow onto the web, also from either side thereof.

12. The edge cleaner of any preceding claim, wherein an evacuation rate through the evacuation opening exceeds a combined ejection rate through the orifices, counted as total mass flow.

13. The edge cleaner of claim 12, wherein the ratio is 2: 1 or more, such between 2: 1 and 20: 1, e.g. about 3-5: 1 or 10-15: 1.

14. The edge cleaner of any preceding claim, wherein the groove is defined by three elements of the edge cleaner, a first side element defining the first lateral sidewall, a second side element defining the second lateral sidewall and one base element defining the bottom, wherein the first and the second side element comprises the ejection openings, and wherein the evacuation opening is defined in the base element.

15. The edge cleaner of claim 14, wherein the side elements are removably attached to the base element.