EP1535869A1

EP1535869A1 - Device for transporting a strip of foil material along a straight path

Info

Publication number: EP1535869A1
Application number: EP03078722A
Authority: EP
Inventors: Frederik Simon Van Heeswijk
Original assignee: Seal Graphics Europe BV
Current assignee: Seal Graphics Europe BV
Priority date: 2003-11-25
Filing date: 2003-11-25
Publication date: 2005-06-01
Also published as: WO2005051819A1

Abstract

The invention relates to a device for transporting a strip (2) of foil material, for instance a sheet of plastic of paper, along a substantially straight path from a supply station (3) to a processing station, for instance a printer, a laminator or the like, which device comprises:

sensing means for sensing deviations in the nominal transporting direction of the strip; and

braking means (8,9) which engage on the strip and, under the control of the sensing means, subject the strip to a braking force on its left side edge (10) or on its right side edge (11) depending on the direction of a determined deviation,
such that deviations in the nominal transporting direction are corrected and the strip (2) leaves the device within a preset tolerance relative to the nominal transporting direction.

Description

The invention lies in the field of monitoring and controlling with great precision the path of a strip of foil material for feeding into a processing device such as an inkjet printer, a laminator or a device which performs both said functions.
A very great accuracy is often required for such a feed. For instance in the case where a very long strip must be transported it often occurs that, owing to a very small misalignment relative to the nominal path, there is a very considerable change in transverse position between the beginning of the strip and the end of the strip. This is highly undesirable and sometimes even interferes with the proper operation of the printer or the laminator, since the strip sometimes runs up against one lateral boundary and there deforms or even gets damaged. In some cases this can even result in malfunction of the equipment, which is highly undesirable for the intended professional applications.
It is an object of the invention to make provisions which ensure that the path of a strip of foil material to be fed into a processing station is maintained with great precision, so that the stated problems of the prior art no longer occur.
With a view to the above, the invention provides a device for transporting a strip of foil material, for instance a sheet of plastic or paper, along a substantially straight path from a supply station to a processing station, for instance a printer, a laminator or the like. A technically relatively simple embodiment consists of the braking means taking a mechanical form.
This latter mechanical form can be particularly embodied in a device wherein the braking means comprise two rollers or pairs of rollers having brakes which are controllable by the sensing means and which engage on respectively the left side edge and the right side edge of the strip.
In yet another embodiment the device with the mechanical braking means has the special feature that the braking means comprise two co-acting rollers which can be braked and which extend in transverse direction over substantially the whole width of the strip, the relative angular positions of said rollers being controllable in a vertical plane by the sensing means.
Requiring less maintenance and having a simpler embodiment is a variant wherein the braking means take a pneumatic form and comprise two suction nozzles in respectively the zone of the left side edge and the right side edge of the strip, which suction nozzles are each connected to underpressure means, wherein the operation of the suction nozzles is controlled by the sensing means.
The sensing means can take for instance a mechanical or optical form. In these cases the sensing means are separate components subject to possible malfunction, which can have a fundamental influence on the proper operation of the device.
Therefore recommended is an embodiment wherein the device does not have separate sensing means, is given a fully self-adjusting form but is nevertheless able to control the path of the foil strip within very narrow tolerances.
A preferred embodiment has in this respect the special feature that the suction nozzles are positioned or can be positioned such that their outer boundaries are situated a chosen distance outside the nominal path, and each of the suction nozzles is connected to an individual underpressure source such that the sensing means and the braking means are integrated.
In order to be able to adapt the device to the width of a foil strip to be processed, an embodiment can be useful wherein the transverse positions of the suction nozzles are adjustable.
For a stable running of the strip a steady and regular support of the strip is desirable. In this respect another embodiment has the special feature that the strip is transported over the surface of a plate, on which surface the suction nozzles debouch.
In order to enhance as far as possible a jolt-free and tension-free transport of a foil strip, use can preferably be made of an embodiment wherein the surface is provided with friction-reducing means.
A specific embodiment has the special feature that each suction nozzle comprises a number of perforations, for instance slots, recessed into a part of said surface. The use of a number of perforations in a guide surface has the advantage that a relatively large suction area, and thereby a relatively great suction and braking force, can be combined with a good support in the zone of the suction nozzle, whereby local deformation of the foil strip is avoided.
Very good results are achieved with an embodiment wherein each suction nozzle comprises a number of slots extending with a considerable directional component transversely of the transporting direction of the strip.
In a practical embodiment, the device has the special feature that each suction nozzle is embodied in a block consisting of an upper plate provided with the perforations and a connecting block which is connected airtightly thereto and which connects the perforations to a common connection for an underpressure source.
It is noted that the device can be readily added to an existing processing device such as a printer or laminator. The device according to the invention can also be integrated with such a processing device.
Said block can be embodied for instance as injection moulded article consisting of plastic or aluminium, of glass-filled PVC or PC, of cast PU, of aluminium modelled by milling or other machining, of steel or of other suitable materials or combinations thereof.
The said friction reduction can be realized by a coating consisting of titanium nitride or a plastic such as PTFE.
The invention will now be elucidated with reference to the annexed drawings of an embodiment. In the drawings:
Fig. 1 shows a partly cut-away top view of a device according to the invention;
Fig. 2 shows a partly transparent view corresponding with Fig. 1,
Fig. 3 shows the device of Fig. 1 and 2 in partly cut-away perspective view;
Fig. 4 shows a partly transparent view corresponding with Fig. 3;
Fig. 5 shows the detail V of Fig. 3;
Fig. 6 shows the detail VI of Fig. 4;
Fig. 7 shows an exploded view of an embodiment of a suction block according to the invention; and
Fig. 8 is a perspective view of the assembled suction block of Fig. 7.
Fig. 1-4 show a device 1 according to the invention. A paper strip is carried out of a supply tray 3 in a direction 4 to a partly drawn device, for instance a laminator. It is carried for this purpose through the pinch of laminating rollers 5, 6 via a flat support plate 7.
Respective suction nozzles 8, 9 are positioned in the edge zones of the nominal path of strip 2.
Fig. 5 and 6 show nozzle 9 on larger scale, so that the details can be seen better. It is apparent that the left side edge 10 and right side edge 11 have a mutual distance corresponding to the width of paper strip 2, that the suction slots 12 to be described hereinbelow of suction nozzles 8 and 9 can never be simultaneously covered by paper strip 12. Fig. 1-4 show the nominal position of strip 2 relative to suction nozzles 8, 9. Suction nozzles 8, 9 are connected via respective suction lines 19, 20 to suction means (not shown), particularly fans. In the situation shown in Fig. 1-6 there is a large overlap of the paper strip with slots 12, but there is still a free space left beyond side edge 11, so that air can be drawn therethrough to the suction source without this affecting the friction force with which the paper strip is pressed at the position of nozzle 9 against the relevant surface and thereby braked. Only at the moment that an almost complete closure of slots 12 has occurred does the paper strip undergo a braking influence, due to the suction force, which will be manifested as a change in the path.
The shown distance over which the suction slots 12 of the two nozzles 8 and 9 extend outside side edges 10, 11 in the shown nominal situation determines the tolerance within which the running of paper strip 2 can be held constant.
In a particular embodiment the positions of nozzles 8, 9 can be adjustable for the purpose of adaptation to the width of the paper strip.
Fig. 7 and 8 show the possible construction of a suction nozzle 9, which can be identical to nozzle 8. An upper plate provided with the slots 12 is covered airtightly on its underside by an intermediate plate 15 which is connected thereto and has a row of perforations 16 which are in register with slots 12. In the assembled situation according to Fig. 8, a hollow connecting block 17 connects airtightly to perforations 16, which block is embodied as a trough with a passage and a connection 18 which can connect the cavity to suction line 20.
It will be apparent from Fig. 7 and 8 that the construction of a suction block can be very simple.
The structure according to the invention provides a superior transporting accuracy, wherein deviations from the nominal path can be reduced to negligible proportions.

Claims

Device for transporting a strip of foil material, for instance a sheet of plastic or paper, along a substantially straight path from a supply station to a processing station, for instance a printer, a laminator or the like, which device comprises:

sensing means for sensing deviations in the nominal transporting direction of the strip; and

braking means which engage on the strip and, under the control of the sensing means, subject the strip to a braking force on its left side edge or on its right side edge depending on the direction of a determined deviation,

such that deviations in the nominal transporting direction are corrected and the strip leaves the device within a preset tolerance relative to the nominal transporting direction.
Device as claimed in claim 1, wherein the braking means take a mechanical form.
Device as claimed in claim 2, wherein the braking means comprise two rollers or pairs of rollers having brakes which are controllable by the sensing means and which engage on respectively the left side edge and the right side edge of the strip.
Device as claimed in claim 2, wherein the braking means comprise two co-acting rollers which can be braked and which extend in transverse direction over substantially the whole width of the strip, the relative angular positions of said rollers being controllable in a vertical plane by the sensing means.
Device as claimed in claim 1, wherein the braking means take a pneumatic form and comprise two suction nozzles in respectively the zone of the left side edge and the right side edge of the strip, which suction nozzles are each connected to underpressure means, wherein the operation of the suction nozzles is controlled by the sensing means.
Device as claimed in claim 5, wherein the suction nozzles are positioned or can be positioned such that their outer boundaries are situated a chosen distance outside the nominal path, and each of the suction nozzles is connected to an individual underpressure source such that the sensing means and the braking means are integrated.
Device as claimed in claim 6, wherein the transverse position of the suction nozzles are adjustable.
Device as claimed in claim 5, wherein the strip is transported over the surface of a plate, on which surface the suction nozzles debouch.
Device as claimed in claim 8, wherein the surface is provided with friction-reducing means.
Device as claimed in claim 5, wherein each suction nozzle comprises a number of perforations, for instance slots, recessed into a part of said surface.
Device as claimed in claim 10, wherein each suction nozzle comprises a number of slots extending with a considerable directional component transversely of the transporting direction of the strip.
Device as claimed in claim 10, wherein each suction nozzle is embodied in a block consisting of an upper plate provided with the perforations and a connecting block which is connected airtightly thereto and which connects the perforations to a common connection for an underpressure source.