GB1584770A - Guide device for flexible webs - Google Patents

Description

(54) A GUIDE DEVICE FOR FLEXIBLE WEBS (71) We, BACHOFEN & MEIER, a Company organised under the laws of Switzerland of CH-8180 Bulach, Switzerland do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be described in and by the following statement: In manufacturing or processing works, it occurs again and again that an endless web must be diverted at a particular variable angle. If the webs become spread, or if they are still in a wet condition, guiding cannot be done without contact. As a rule, use was made of a guide roller with an anti-stick coating, e.g. Teflon or silicone.

Furthermore, chromium-plated and cooled steel rollers have been proposed for guiding webs. In that case, in conjunction with the normally warm substrate web, surface condensation occured, by which adhesion or building-up on the roller surface was prevented. Any spread was, however, damaged and cooling resulted as an unwanted side effect before drying of the substrate.

Maintaining the width of the web also caused difficulties with the traditional systems and special separate width stretching rollers were necessary in order to prevent formation of folds in unguided webs.

The object of the present invention is a guide device for guiding travelling web such as flexible webs of paper, cardboard, plastics, foils, textiles, etc., by which the above-mentioned disadvantages inherent in the previous designs should be remedied.

The guiding without contact is combined at the same time with a width stretching effect.

According to the present invention, there is provided a guide device for guiding a travelling elongate web during a change of direction, the device comprising an elongate hollow body having an outer curved surface through which fluid can issue to maintain the web travelling over the surface free of contact with the surface, the surface comprising a plurality of curved plates extending longitudinally of the body having inner edges within the body and outer edges outside the body and spaced from each other to form longitudinal slits so that, in use, they extend across the web transversely to the direction of movement of the web, said slits being curved and directed towards the movement of the web, together with means to supply fluid to and out of the slits so as to provide an air cushion between the said outer surface and the web.

An embodiment of the object of the invention is shown by way of example in the attached drawing, where: FIGURE 1 is a perspective view of the web guiding member, partly in section, FIGURE 2 is a diagrammatic end view of the above, FIGURE 3 is a diagrammatic arrangement of the compressed air unit for the guiding device.

1 designates a web guiding member which consists of a long, quadrant-shaped hollow body, shown in section. The body 1 is tightly closed at both ends by walls 2.

The hollow body 1' is divided by rigid intermediate partitions 3 into zones 4, 4' and 4". The curved outer surface of hollow body 1' is provided with parallel nozzle slits 5 and against the nozzles there are fluid guideways such as air guideways 6. The nozzle slits 5 and air guideways 6 are defined by spaced plates 7 and 8. Centre plates 8 are several times wider than plates 7. Three plates 7 are above and four plates 7 below each plate 8. Plates 7, 8 have along one of their long edges an inwardly-pointing curve 9 which serves to direct the air stream. The curves 9 on plates 7 above plates 8 are then on the upper side, and the curves 9 on plates 7 below plates 8 are also on the upper side. At a distance from plates 7, 8 and inside the hollow lody 1' an air supply means in the form of a distributor or sieve 10 is positioned. The air distributor 10 is at a constant distance from the surface of the quadrant-shaped hollow body 1' of the web guiding member 1. The air supply means also comprises a blast tube 11 running longitudinally through the hollow body 1', and has air outlets 12 directed towards plates 7, 8.

There is such an air outlet 12 in each of the zones 4, 4' and 4".

The blast tube 11 communicates with the compressed air unit (fig. 3). The latter consists of a conventional inlet cone 13 fitted with an air filter and a fan 14, between which there is a control damper 15.

Duct 16 leads from fan 14 to a distributor chamber 17, there being another damper 18 before the latter. The distributor chamber 17 has three branches 19, 19', 19", and each has its own control damper 20.

Branch tubes 21, 21', 21", shown in dotted lines, lead from branches 19 to chambers 22, 22', 22" in an air supply regulator 23, which is close to web guiding member 1.

Air is supplied to zone 4 in hollow body 1' through centre chamber 22, to both zones 4' through chamber 22' and to both outer zones 4" through chamber 22".

The width stretching effect on the web 25, for example a transparent foil, running over the curved surface of the outer shell of hollow body 1' of web guiding member 1 can be regulated by the relevant dampers 20. This is obtained when there is a greater supply of air to centre chamber 22 and thus to zone 4 in web guiding member 1.

The total air supply to web guiding member 1 can be regulated by damper 20 in distributor chamber 17.

The purpose of the wide plates 8 is to create a nozzle-free neutral air gap between upper plates 7 on the so-called inlet side of web 25 and lower plates 7 on outlet side. The air stream emerging from nozzles 5 will ensure contact-free guiding of web 25 in the region of the web guiding member 1.

Web 25 is lifted from plates 7, 8 by the air supplied through nozzles 5 underneath it and is consequently suspended on an air cushion. A width stretching effect is also obtained by lifting web 25 by means of air pressure. Conveying the web 25 over an air cushion, together with width stretching, ensures trouble-free operation, even with delicate and sensitive webs.

The invention as described is suitable for conveying and guiding flexible webs of all types which have to be free from contact.

WHAT WE CLAIM IS 1. A guide device for guiding a travelling elongate web during a change of direction, the device comprising an elongate hollow body having an outer curved surface through which fluid can issue to maintain the web travelling over the surface free of contact with the surface, the surface comprising a plurality of curved plates extending longitudinally of the body having inner edges within the body and outer edges outside the body and spaced from each other to form longitudinal slits so that, in use, they extend across the web transversely to the direction of movement of the web, said slits being curved and directed towards the movement of the web, together with means to supply fluid to and out of the slits so as to provide an air cushion between the said outer surface and the web.

2. A guide device, according to claim 1 wherein a slit free gap is provided by means of at least one wider plate between the remaining plates in the longitudinal middle part of the surface.

3. A guide device according to claim 1 or 2 wherein the longitudinal side parts of the plates are provided with inwardlydirected curves.

4. A device according to any of the preceding claims, wherein the fluid supply means includes a sieve type air distributor and a blast tube with an air compressor unit which is adapted for communication.

5. A guide device, according to claim 4, wherein the hollow body is divided by partitions into zones, and wherein in the region of each zone the blast tube has fluid outlets.

6. A guide device, according to any of the claims 3 to 5, wherein the curves on the plates are on upper longitudinal sides at the inlet side of the web, and conversely are on the lower longitudinal sides at the outlet side of the web.

7. A guide device, according to any of claims 5 and 6, wherein means is provided to control the fluid pressure to the blast tube whereby the fluid pressures in the zones are kept different from one another.

8. A guide device, for elongate webs, substantially as described herein with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. There is such an air outlet 12 in each of the zones 4, 4' and 4". The blast tube 11 communicates with the compressed air unit (fig. 3). The latter consists of a conventional inlet cone 13 fitted with an air filter and a fan 14, between which there is a control damper 15. Duct 16 leads from fan 14 to a distributor chamber 17, there being another damper 18 before the latter. The distributor chamber 17 has three branches 19, 19', 19", and each has its own control damper 20. Branch tubes 21, 21', 21", shown in dotted lines, lead from branches 19 to chambers 22, 22', 22" in an air supply regulator 23, which is close to web guiding member 1. Air is supplied to zone 4 in hollow body 1' through centre chamber 22, to both zones 4' through chamber 22' and to both outer zones 4" through chamber 22". The width stretching effect on the web 25, for example a transparent foil, running over the curved surface of the outer shell of hollow body 1' of web guiding member 1 can be regulated by the relevant dampers 20. This is obtained when there is a greater supply of air to centre chamber 22 and thus to zone 4 in web guiding member 1. The total air supply to web guiding member 1 can be regulated by damper 20 in distributor chamber 17. The purpose of the wide plates 8 is to create a nozzle-free neutral air gap between upper plates 7 on the so-called inlet side of web 25 and lower plates 7 on outlet side. The air stream emerging from nozzles 5 will ensure contact-free guiding of web 25 in the region of the web guiding member 1. Web 25 is lifted from plates 7, 8 by the air supplied through nozzles 5 underneath it and is consequently suspended on an air cushion. A width stretching effect is also obtained by lifting web 25 by means of air pressure. Conveying the web 25 over an air cushion, together with width stretching, ensures trouble-free operation, even with delicate and sensitive webs. The invention as described is suitable for conveying and guiding flexible webs of all types which have to be free from contact. WHAT WE CLAIM IS

1. A guide device for guiding a travelling elongate web during a change of direction, the device comprising an elongate hollow body having an outer curved surface through which fluid can issue to maintain the web travelling over the surface free of contact with the surface, the surface comprising a plurality of curved plates extending longitudinally of the body having inner edges within the body and outer edges outside the body and spaced from each other to form longitudinal slits so that, in use, they extend across the web transversely to the direction of movement of the web, said slits being curved and directed towards the movement of the web, together with means to supply fluid to and out of the slits so as to provide an air cushion between the said outer surface and the web.

2. A guide device, according to claim 1 wherein a slit free gap is provided by means of at least one wider plate between the remaining plates in the longitudinal middle part of the surface.

3. A guide device according to claim 1 or 2 wherein the longitudinal side parts of the plates are provided with inwardlydirected curves.

4. A device according to any of the preceding claims, wherein the fluid supply means includes a sieve type air distributor and a blast tube with an air compressor unit which is adapted for communication.

5. A guide device, according to claim 4, wherein the hollow body is divided by partitions into zones, and wherein in the region of each zone the blast tube has fluid outlets.

6. A guide device, according to any of the claims 3 to 5, wherein the curves on the plates are on upper longitudinal sides at the inlet side of the web, and conversely are on the lower longitudinal sides at the outlet side of the web.

7. A guide device, according to any of claims 5 and 6, wherein means is provided to control the fluid pressure to the blast tube whereby the fluid pressures in the zones are kept different from one another.

8. A guide device, for elongate webs, substantially as described herein with reference to the accompanying drawing.