GB2379918A

GB2379918A - Labelling Machine

Info

Publication number: GB2379918A
Application number: GB0122742A
Authority: GB
Inventors: Peter Roman; Peter John Woolls
Original assignee: SOVEREIGN LABELLING SYS Ltd
Current assignee: SOVEREIGN LABELLING SYS Ltd
Priority date: 2001-09-21
Filing date: 2001-09-21
Publication date: 2003-03-26
Anticipated expiration: 2021-09-21
Also published as: GB0122742D0; GB2379918B

Abstract

A labelling machine comprises a web 36 of labels separated from one another by perforations, rollers 16, 18 which draw web 36 from roll 10, a further pair of rollers 24, 26 and tearing means 22, wherein when the perforations are aligned with tearing means 22 the rollers tense web 36, by stopping the rollers 16, 18 whilst still driving rollers 24, 26, and tearing means 22 separates a label 40 from web 36. A sensor 38 detects when the perforations are aligned. The rollers 24, 26 are separable, allowing web 36 to advance through them until label 40 is in position to be separated. Roller 26 may drive a label transporter belt 32, which uses a vacuum applied through holes in the belt 34 to hold said labels. A vacuum box 20 may be used to hold the web in alignment between rollers 16, 18 and 24, 26. The perforations may be torn by either a gas jet or small punctuations along the perforations caused by pins or blades.

Description

LABELLING MACHINE Field of the invention The present invention related to a labelling machine.

Background of the invention EP-0 682 636 disclosed a labelling machine having a label supply which comprises a roll about which there is wound a continuous web of linerless self-adhesive labels separated from one another by perforations, the web having an adhesive coating on a first side and the second side of the web being releasable from the adhesive coating on the first side, the machine having means for detaching individual labels from the roll and means for transporting the detached labels individually towards a station where they are applied to the articles to be labelled, the detaching means comprises a first pair of drive rollers in frictional contact with web unwound from the roll, a second pair of drive rollers arranged downstream of the first pair, tearing means arranged between the two pairs of drive rollers for tearing the web at the perforations between the two pairs of driver rollers, and means for controlling the drive rollers and the tearing means in such a manner that when a perforation is aligned with the tearing means, the section of the web between the two pairs of drive rollers is tensioned by driving the second pair of drive rollers at a higher speed than the first pair and the tearing means are activated to detach the label gripped by the second pair of rollers from the remainder of the web.

EP 0 682 636, addresses the problem of the label web adhering to the tearing means (constituted by a breaker bar extending across the full width of the web) and proposes to have the adhesive side of the web facing away from the breaker bar. Regardless of the orientation of the web,

however, after the leading label has been detached from the web, the web has a tendency to curl. If the leading edge of the web does not align perfectly with the nip of the second pair of drive rollers serious problems occur as the web tends to fold over and adhere to itself.

Furthermore, in this prior art reference, the two sets of drive rollers are constantly driven but at different speeds. The speeds of the two pairs of rollers need to be carefully synchronised. If the second pair is driven too fast, this will result in over-tensioning and undesired tearing of the web, while driving the second pair too slowly could result in the tension being too low for the breaker bar to tear the web at the perforations.

Summary of the invention.

With a view to mitigating the foregoing problem, in the present invention the second pair of rollers are separable from one another and the control means are operative during a tearing operation to stop the first pair of drive rollers when the perforations are in line with the tearing means and to tension the web by means of the second pair of drive rollers, the control means being further operative between tearing operations to advance the web by means of the first pair of drive rollers and to separate the rollers of the second pair to assist in the unhindered passage therethrough of the leading edge of the web.

The present invention overcomes the problem of speed matching in that the first pair of rollers is stopped during the tearing operation. This stopping is preferably effected when the leading edge of the web is detected by a sensor which is positioned such that at the same instant a perforation is aligned with the tearing means. The speeds of operation of the two pairs of rollers can therefore be independent of one another and neither is critical.

Furthermore, the supply of labels can in the present invention be discontinued at will so that the detaching of labels from the roll can be performed on demand. This is important because hold ups can occur on the conveyor carrying the articles to be labelled.

In a preferred embodiment of the invention, the second pair of drive rollers are formed by a movable roller and a fixed roller that additionally acts as a guide roller of a conveyor belt for transporting the label detached from the web.

Advantageously, the labels are transported on the conveyor belt with their adhesive sides facing away from the belt and a vacuum box is provided below the belt to assist in holding the individual labels against the belt.

It is also preferable to use a vacuum or a jet of gas from the opposite side to maintain the leading edge of the web in contact with a flat guide surface as it is being advanced by the first pair of drive rollers towards the gap between the separated second pair of drive rollers.

It has been found that a bar extending across the entire width of the web does not assure consistent tearing of the perforations. This method of tearing is the equivalent of applying a force to the web while it is stretched over a corner of small radius and, as the perforations may vary, the force needed will also vary from one roll to another or even from one label to the next.

Forming the labels so that they always tear easily could result in the web tearing when accelerated rapidly while using stronger perforations to avoid such stoppages could result in the perforations not being torn by the breaker bar.

In accordance with a preferred embodiment of the invention, the tearing means include a puncturing means having significantly lesser width than the label. The puncturing means are in this case required only to initiate a tear which then propagates across the full width of the label as a result of the applied tension.

Such a method of tearing the perforations is not practicable in the case of the prior art proposal in which the labels are constantly driven during the tearing operation. The cumulative effect of this uneven tension across the width of the label would cause puckering and unacceptable creases along the length of the web. In the present invention, however, the stresses do not accumulate because the web is stopped during the tearing operation.

Conveniently, the puncturing means should be symmetrical about the longitudinal central axis of the web so that the tear propagates symmetrically and does not cause the label to skew. Ideally, it has been found that two punctures each formed at between one quarter and one third of the width of the labels away from one of the respective lateral edges achieves the most effective and reliable tearing of the labels.

The puncturing means may be formed as pins or sharp blades but it is alternatively possible to use an air blast to avoid any contact with the adhesive on the web.

Of course, all surfaces of the machine that contact the adhesive side of the web and the labels need to have a nonstick surface such as PTFE or a silicone release coating.

Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 show schematically part of a labelling machine of the invention during different stages of its operation.

Detailed description of the preferred embodiment In both drawings, labels are supplied in the form of a continuous web 36 wound on a roll 10. The web is linerless and has a non-stick side 14 and an adhesive coated side 12.

The individual labels are separated from one another by lines of perforations extending across the width of the web.

The web 36 passes through a first pair of intermittently driven rollers 16,18 and is guided over a vacuum box 20 towards a second pair of drive rollers 24,26.

A puncturing device 22 is arranged between the two pairs of rollers.

The roller 24 can move into contact with the roller 26, as is shown in Figure 2, or can be separated from the roller 26 to leave a gap. The roller 26 is one of three rollers 26, 28,30 over which a continuous conveyor belt 32 is guided.

The belt 32 is formed with holes and the section of the belt 32 between the rollers 26 and 30 passes over a second vacuum box 34 and beneath a optical edge detector 38.

Figure 1 shows the labelling machine shortly after a label 40 has been separated from the web 36 and Figure 2 shows the machine immediately before the separation of a label from the web.

At the end of a separation cycle, the leading edge of the web will lie level with the perforating device 22 and the rollers 16,18 will be stopped. The free end of the web will be held flat against the vacuum box 20. As an alternative a light air pressure could be used to urge the web against a flat surface.

The first phase in separating the next label from the web 36 is to engage the drive to the rollers 16 and 18 and to separate the rollers 24 and 26. The rollers 26 continues to rotate to transport the label 40 on the conveyor belt 32 to the next station in the labelling machine for later application to an article.

As now shown in Figure 1, the web 36 is advanced by the rollers 16,18 towards the gap between the rollers 26,26 and on to the conveyor 32. The leading edge of the web 36 is sensed by the detector 38 at the same time as the next perforated line lies level with the puncturing device 22.

Upon sensing of the edge of the web, the rollers 16 and 18 are braked and the roller 24 is moved to close the nip between it and the roller 26. The combined effect of the brake applied to the rollers 16, 18 and the driving of the rollers 24,26 is to tension the section of the web 36 lying between these two pairs of rollers.

The puncturing device 22, which may comprise a pin, a narrow blade or even a jet of air is next actuated to make two small punctures in the perforations a quarter to a third of the way in from the lateral edges. This commences a tear which then propagates laterally under the applied tension to separate the leading label from the web. The rollers 24 and 26 remain together for long enough to separate the leading label 40 from the web 36 and to carrying safely on to the conveyor 32. When next a label is required, the rollers 24 and 26 are separated from one another to create a gap for receiving the free end of the web and drive to the rollers

16,18 is re-engaged to repeat the operation starting from the position shown in Figure 1.

Claims

1. labelling machine having a label supply which comprises a roll about which there is wound a continuous web of linerless self-adhesive labels separated from one another by perforations, the web having an adhesive coating on a first side and the second side of the web being releasable from the adhesive coating on the first side, the machine having means for detaching individual labels from the roll and means for transporting the detached labels individually towards a station where they are applied to the articles to be labelled, the detaching means comprises: e a first pair of drive rollers in frictional contact with web unwound from the roll,

'a second pair of drive rollers arranged downstream of the first pair, * tearing means arranged between the two pairs of drive rollers for tearing the web at the perforations between the two pairs of driver rollers, and 'means for controlling the drive rollers and the tearing means in such a manner that when a perforation is aligned with the tearing means, the section of the web between the two pairs of drive rollers is tensioned by driving the second pair of drive rollers at a higher speed than the first pair and the tearing means are activated to detach the label gripped by the second pair of rollers from the remainder of the web, characterised in that the second pair of rollers are separable from one another and in that the control means are operative during a tearing operation to stop the first pair of drive rollers when the perforations are in line with the tearing means and to tension the web by means of the second pair of drive rollers, the control means being further operative between tearing operations to advance the web by means of the first pair of drive rollers and to separate the

rollers of the second pair to assist in the unhindered passage therethrough of the leading edge of the web.

2. A labelling machine as claimed in claim 1, wherein one of the rollers of the second pair acts additionally as a drive roller of a continuous belt that forms part of the transporting means.

3. A labelling machine as claimed in claim 2, wherein the belt is perforated and a vacuum box is provided to maintain the detached individual labels in contact with the belt.

4. A labelling machine as claimed in any preceding claim, wherein a vacuum box is provided to maintain the free end of the web in alignment with the gap between the second pair of drive rollers after the leading label has been detached from the web.

5. A labelling machine as claimed in any preceding claim, wherein the tearing means comprise means for puncturing the web at the perforations, the puncture (s) being significantly narrower than the width of the labels.

6. A labelling machine as claimed in claim 5, wherein the puncturing device comprises a pin or a blade.

7. A labelling machine as claimed in claim 5, wherein the puncturing device comprises a gas jet.

8. A labelling machine constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.