WO2004041697A1

WO2004041697A1 - An apparatus for guiding a web of packaging material, and a method of removing dust

Info

Publication number: WO2004041697A1
Application number: PCT/SE2003/001539
Authority: WO
Inventors: Per Lagerroth; Mats Turesson
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2002-11-07
Filing date: 2003-10-03
Publication date: 2004-05-21
Also published as: AU2003265203A1; SE0203283D0; SE523995C2; SE0203283L

Abstract

The present invention relates to an apparatus for guiding a web of packaging material, comprising a groove (11) extending along the direction of transport of the web, in which groove one longitudinal edge of the web is intended to run during advancement of the web. The apparatus further includes an aperture in the wall of the groove (11) for applying a partial vacuum for the removal of air and dust from the groove (11) and its ambient surroundings. Further, the present invention relates to a method of removing dust.

Description

AN APPARATUS FOR GUIDING A WEB OF PACKAGING MATERIAL, AND A METHOD OF REMOVING DUST

TECHNICAL FIELD The present invention relates to an apparatus for guiding a web of packaging material comprising a groove extending along the direction of transport of the web, in which groove an elongate edge of the web is intended to run during advancement of the web. The present invention further relates to a method of removing dust.

BACKGROUND ART

There are innumerable methods of forming, folding and fusing together plastic film-coated paper material in order to produce packages for liquid foods such as milk, juice and the like.

One commercially viable method of producing a food package and filling it with a liquid food is shown in schematic form in Fig. 1. A paper web 1 is formed continually into a tube by both longitudinal edges la-b of the paper web being fused together and the pertinent food is thereafter filled into the just-formed tube. In the next process step, the tube is divided into packages by being transversely sealed and severed along the transverse seal so that cushion-shaped packaging blanks are formed which are finally formed in that the corners are folded in and secured to the side surfaces of the package. A commercially well-known example of a package formed in this manner is the rectangular block shaped package Tetra Brik® produced by Tetra Pak.

The packaging material comprises at least one layer of paper and at least one layer of plastic. The plastic layer imparts to the paper layer the requisite resistance to liquid and is moreover intended to be partly melted so as to fuse together different parts of the packaging material.

In today's filling machines for producing packages for liquid foods there are a number of places where the position of the paper web is guided along the length of the web and transversely of the length of the web. The paper web is usually led by a

^' number of bending rollers 2 and different forms of rails 3 and wheels 4 (for clarity's sake, only a few rollers, rails and wheels have been marked in Figs. 1 and 2). In order to guide the paper web in a direction transversely of its longitudinal- and movement direction, it is common practice to cause the paper web to be urged in the transverse direction against an upstanding rail which is of a certain physical extent along the direction of movement of the web and along a direction parallel to the normal direction of the web. By ensuring that the web, on its passing transport, constantly abuts against this rail, it will be ensured that its position in the transverse direction is defined. One method of urging the paper web against this rail is to clamp the web between two freely rotating wheels whose shafts lie a few degrees offset obliquely in relation to the transverse direction of the web so that that part of the circumferential surface which releases contact with the web last lies slightly closer to the rail than that part of the circumferential surface of the wheel which initially comes into contact with the paper web.

Another method of guiding the position of the paper web in the transverse direction is to provide the bending rollers with rings which are of larger radius than the circumferential surface of the bending rollers and which may be displaced along the axial direction of the bending rollers. The normal practice is then to dispose two guide rings on the bending roller and that the distance between these rings is the same the width of the paper web. By such means, it will be ensured that the position of the paper web is defined in the transverse direction exactly at the bending roller. Such a bending roller is disclosed, for example, in US-A-6,047,873 and in Fig. 2 in the present application. The bending 2 is provided with two rings 2A, 2b, the web 1 being intended to run between the rings 2a, 2b against the circumferential surface of the bending roller 2.

A feature common to these types of web guides is that they contribute in the formation of paper or plastic dust. The harder the guiding is in the transverse direction, the greater will be the amount of dust that risks being created.

In order to remove the dust from the paper web, there are innumerable variations of vacuum cleaners and compressed air systems. US-A-6, 148,831 describes, for example, a method of cleaning a web by removing dust and other particles by first aspirating on the paper web in order to release the dust from the web, and thereafter suck the released dust away. This publication also describes how to realise a special air vortex for realising the desired cleaning. However, this construction is adapted to the paper industry and is complicated and requires considerable space. Thus, this construction does not offer any solution to the above- outlined problem in dust formation in a filling machine.

Hence, there is no totally satisfactory solution as to how to guide a paper web and how to avoid dust being spread excessively in the packaging machine.

SUMMARY OF THE INVENTION

One object of the present invention is thus to realise a solution to the above- outlined problems. This object has been attained according to the present invention by means of an apparatus of the type disclosed by way of introduction which has been given the characterising feature that the apparatus further includes an aperture in the wall of the groove for applying a partial vacuum for removal of air and dust from the groove and its immediate surroundings. By forming the apparatus in this manner, there will be obtained, on the one hand, a simple and reliable guiding of the web at the same time as dust is removed at that place where the greatest quantity of the dust is formed, namely where the web edge abuts against different types and forms of guides. Moreover, this construction gives a combined effect: namely that the groove forms a nozzle extending along the longitudinal edge of the web which makes the suction effect extremely effective. By providing suction already at the source of creation of the dust, the dust will not have time to dissipate in the air and it is possible to remove large quantities of dust in relation to the volume of air which is removed by suction. In prior art constructions, the dust is removed throughout the entire width of the web without focusing on where the dust is formed, for which reason it becomes necessary to employ much larger-scale equipment and larger volumes of air must be removed by suction. By disposing the partial vacuum in the groove, the advantage will be moreover afforded that the dust does not have time to adhere particularly hard to the web before being removed, which further contributes in the feature of employing simple suction equipment and nevertheless obtaining sufficient suction effect. According to one preferred embodiment, the abutment surface is formed so that the end which is passed last by an advanced web is bevelled in a direction away from the web so as to obtain an even transition in the movement of the web from being guided to being unguided.

Advantageously, the above mentioned aperture for disposing partial vacuum is disposed in conjunction with the above mentioned bevelling of the abutment surface. By such means, a large quantity of the dust will be removed directly when the retaining pressure against the edge of the web is released.

According to one preferred embodiment, the walls of the groove are formed so that they form, in the transverse direction of the web a funnel shape tapering towards the above mentioned aperture for providing the partial vacuum. By such means, it is possible to obtain an air current which accelerates during suction into the funnel and which thereby is at a high velocity when it passes the edge of the web. This results in a superior removal of the dust from the paper web being obtained.

According to one preferred embodiment, the groove is formed so that there is a channel which is located, seen in the transverse direction, outside the line along which the web is intended to run and which communicates a first gap between a first of the walls of the groove and one side of the web with a second gap between a second wall opposing the first wall and the second side of the web. By such means, a uniform suction effect will readily be obtained on both sides of the web. On the one hand, dust is removed on both sides, and, on the other hand, there will be obtained an equally large suction effect in the normal direction of the web on both sides, which reduces the risk that the web might be sucked against any of the walls of the groove. This latter occurrence could take place if the tensioning of the web is insufficient in relation to the distance between the web and the walls of the groove extending over the web. The above mentioned objects have also been attained by a method of removing dust from a web of packaging material comprising the steps of: advancing the web so that one longitudinal edge thereof runs in a groove extending along the direction of transport of the web, and applying a partial vacuum to the groove for removing air and dust. As was mentioned above, the advantages will be attained that the dust is removed adjacent its source, and moreover the advantage will be attained, as was mentioned above, that the groove forms a nozzle extending along the edge of the web. Preferred embodiments of the present invention are apparent from the appended subclaims.

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 shows in principle how a web of packaging material may be drawn through a packaging machine;

Fig. 2 shows, on a larger scale, a portion of the Drawing of the packaging material illustrated in Fig. 1;

Fig. 3 shows a web guide apparatus seen from the side which is provided with a groove in which the web is intended to run; Fig. 4 shows the apparatus illustrated in Fig. 3 seen straight from above, where the paper web is intended to run parallel with the plane of the Drawing from below and upwards on the Drawing sheet;

Fig. 5 shows the apparatus illustrated in Figs. 3 and 4 seen straight in the transverse direction of the web; and Fig. 6 shows the apparatus illustrated in Figs. 3 to 5 seen straight in the longitudinal direction of the web from that side which is last in contact with a bypassing portion of the web.

DETAILED DESCRIPTION OF ONE PREFERRED EMBODIMENT As will be apparent from Fig. 3, the guide apparatus 10 includes a groove 11 in which one longitudinal edge la or lb of the paper web is intended to run. The groove 11 extends throughout the entire apparatus 10 and thus has open ends in the end pieces 10a, 10b of the guide apparatus 10 (see Fig. 6). Seen from the end piece 10a (see Fig. 3 and 6), the groove 11 has a so-called keyhole configuration with an inner portion 11a in the transverse direction A which is of larger cross section than an outer portion lib. Outermost, the groove 11 has a conical portion lie which forms a funnel which opens towards the paper web. The guide apparatus 10 is of one piece construction from an easily processed material, such as some suitable form of plastic. The keyhole shape of the groove 11 is employed for securing a rule 12 which forms an abutment surface for the bypassing longitudinal edge la, lb of the web 1. The rule 12 is made of a harder material such as, for example, a metal. The rule 12 is, for example, formed from a rod which has been provided with a planar surface 12b. In its ends, the rule 12 has been provided with bevels 12c, 12d in order to commence and terminate the contact with the longitudinal edge la, lb of the web 1 in a gentle manner.

In order to cause the longitudinal edge la, lb of the web 1 to run against the abutment surface 12b of the rule 12, the guide apparatus 10 is provided with two clamping wheels 13a, 13b which rotate freely and which between them clamp the web 1. The abutment surface 12b of the rule 12 extends in the same direction as the running direction A of the web and the wheels 13 a, 13b are obliquely inclined a few degrees so that they draw the web 1 outwards somewhat towards the guide apparatus 10 (see Fig. 4) in the transverse direction B of the web 1.

At that portion 10c which the paper web 1 first passes in the guide apparatus 10, the walls lid and lie of the groove display a first extent in the transverse direction B. At one portion lOd which the web 1 last passes in the guide apparatus, the walls lid, lie display a second extent in the transverse direction B which is greater than the above mentioned first extent.

The first portion 10c of the web 1 in the transport direction A has a groove 11 which only displays the circular cross section 11a and the straight walls lib out towards the web 1, while the second portion lOd has a groove 11 which also displays the funnel-shaped portion lid open towards the web 1. At this funnel-shaped portion lid with extra long groove walls lid, lie, the guide apparatus is further provided with an aperture 14 to which a partial vacuum (not shown) is extended to be connected. This source of partial vacuum may be a standard vacuum cleaner which delivers a vacuum of the order of magnitude of 10- 20%, i.e. 0,1-0,2 bars partial vacuum. This aperture 14 is, via a channel in the guide apparatus, in communication with a aperture 15 which discharges in the bottom of the groove 11 in the centre of the above mentioned portion lOd with long groove walls lid, lie. In order further to amplify the funnel configuration of the walls lie, lid of the groove 11, the funnel-shaped walls lie, lid have been provided with a bore 16 which extends directly down to the aperture 15 in the bottom of the groove 11.

The rule 12 is designed so that it extends into the portion lOd displaying long groove walls 1 Id, lie and terminates by a bevel 12d immediately before the aperture 15 in the bottom of the groove 11. By such means, the dust which is released when the contact is discontinued between the abutment surface 12b of the rule 12 and the web edge la, lb will be directly sucked in via the aperture 15. Since the bottom 11a of the groove 11 retains its form along the running direction A of the web 1, a communication will be formed after the termination of the rule 12 in the bottom 11a of the groove 11 between the upper and the lower side of the web 1.

When a web 1 passes the guide apparatus, its edge la, lb will be guided by the abutment surface 12b of the rule 12 by the intermediary of a gentle connection

12c and released by the intermediary of a gentle termination 12d. The dust, such as particles of plastic, paper or the Hke, will be sucked into the aperture 15 to a connected source of partial vacuum.

It will readily be perceived by a person skilled in the art that a number of modifications of the embodiments of the present invention described herein are conceivable without departing from the scope of the invention as this is defined in the appended Claims.

For example, the groove may have walls of equal length throughout its entire extent along the direction of transport of the web. Further, it is conceivable that the bore be given funnel-like shape in that it is, for example, formed using a conical milling head, reaming head or the hke. Further, the force on the web can be realised using equipment other than the illustrated wheels.

In addition, it is also possible to use the described apparatus without wheels and/or without rule, in which event it does not execute any specific guiding in the transverse direction but use is made of the favourable shape in order to effectively remove dust by suction.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for guiding a web (1) of packaging material, comprising a groove (11) extending along the direction of transport (A) of the web (1), in which groove (11) a longitudinal edge (la, lb) of the web (1) is intended to run during advancement of the web (1), characterised in that the apparatus (10) further includes an aperture (15) in the wall of the groove (11) for applying a partial vacuum for the removal of air and dust from the groove (11) and its surroundings (1).

2. The apparatus as claimed in Claim 1, which further includes two obliquely inclined rollers (13a, 13b) which clamp the web (1) between them and which apply a force in a direction (B) transversely of the direction of transport (A) on the web (1) in towards the groove (11).

3. The apparatus as claimed in Claim 1 or 2, wherein an abutment surface (12b) which is disposed in the groove (11) extends along the direction of transport (A) of the web (1) and is disposed to come into abutment against the longitudinal edge (la, lb) of the web (1) on advancement of the web (1).

4. The apparatus as claimed in Claim 3, wherein said aperture (15) for applying partial vacuum is disposed in relation to the abutment surface (12b) so that a bypassing longitudinal edge (la, lb) of an advanced web (1) first passes at least a part of the abutment surface (12b) before passing said aperture (15) for applying partial vacuum.

5. The apparatus as claimed in Claim 3 or 4, wherein the abutment surface (12b) is designed so that the end (12d) which is last passed by an advanced web (1) is bevelled in a direction away from the web (1) in the transverse direction (B) of the web (1).

6. The apparatus as claimed in Claim 5, wherein said aperture (15) for applying partial vacuum is disposed in association with said bevel (12d) of said abutment surface (12b).

7. The apparatus as claimed in Claim 5 or 6, wherein said aperture (15) for applying partial vacuum is disposed after said bevel (12d) in said abutment surface

(12b).

8. The apparatus as claimed in one or more of Claims 3 to 7, wherein the walls (lid, lie) of the groove (11) between which the web is disposed to run extend longer over the web (1) in the transverse direction (B) of the web (1) along a portion (lOd) which, along the direction of transport (A) lies adjacent said aperture (15) for applying partial vacuum than at a portion (10c) where the abutment surface (12b) is provided.

9. The apparatus as claimed in one or more of the preceding Claims, wherein the walls (lid, lie) of the groove (11) are designed so that, in the transverse direction (B) of the web (1), they form a funnel-shape (16, lie) tapering towards said aperture (15) for applying partial vacuum.

10. The apparatus as claimed in one or more of the preceding Claims, wherein the groove (11) is designed so that there is a channel (11a) which is located in the transverse direction (B) seen outside that line (12b) along which the web (1) is intended to run and which communicates a first gap between a first of the walls (lie) of the groove and the one side of the web (1) with a second gap between a second wall (lie), opposing the first wall (lid), and the second side of the web (1).

11. A method of removing dust from a web of packaging material, comprising the steps of: advancing the web (1) so that a longitudinal edge (la, lb) thereof runs in a groove (11) extending along the direction of transport (A) of the web (1); and applying a partial vacuum to the groove (11) for removing air and dust.

12. The method as claimed in Claim 11, which further comprises the step of applying, by means of two obliquely inclined rollers (13a, 13b) which clamp the web (1) between them, a force in the direction (B) transversely of the direction of transport (A) of the web (1) in towards the groove (11).

13. The method as claimed in Claim 11 or 12, which further comprises the step of providing, in the groove (1), an abutment surface (12b) which extends along the direction of transport (A) of the web (1) and which is disposed to be in abutment by the longitudinal edge (la, lb) of the web (1) on advancement of the web (1).

14. The method as claimed in Claim 13, comprising the step of applying said partial vacuum so that a bypassing longitudinal edge (la, lb) of an advanced web (1) first passes at least a part of the abutment surface (12b) before passing that point (15) where the partial vacuum is applied to the groove (11).

15. The method as claimed in Claim 13 or 14, further comprising the steps of forming the abutment surface (12b) so that that end (12d) which is last passed by an advanced web (1) is bevelled in a direction (B) away from the web (1), and applying partial vacuum in association with said bevel (12d) of the abutment surface (12b).

16. The method as claimed in Claim 15, wherein said partial vacuum is applied after said bevel (12d) of said abutment surface (12b).