IT202100014420A1 - PRESSURE ROLLER FOR TAP PRODUCTS - Google Patents

Description

DESCRIPTION OF THE INVENTION

TITLE

PRESSURE ROLLER FOR TAP PRODUCTS

TECHNICAL SECTOR

The invention relates to a pressure roller of the type used in cooperation with at least one relative counter-reaction roller in pressure devices for pressing web-like products in paper converting machines or more. in general in machines for converting material into strips.

STATE OF ART

To join more ribbon-like products such as paper, the widespread pressing method is used which avoids the use of glues. It provides a joining device provided with a pressure roller with a surface engraved in relief, generally knurled which cooperates with the smooth surface of a counter-reaction roller, or vice versa.

One or more? web-like products passing between the pressure roller and the counter-roller are joined together thanks to the high localized pressure between the raised surfaces of the pressure roller and the surface of the counter-roller. The pressure roller? generally pushed against the counter-roller by a pneumatic actuator placed between the fixed support and the unit? mobile that supports the pressure wheel itself through bearings.

Pi? Identical joining devices supporting a pressure roller can be arranged side by side in the machine at a single counter-roller, to cover the entire width of the web-like product. The joining devices are independent so as to adapt to the deflection of the counter-roller, which ? connected to its ends? by bearings on a fixed structure.

An example of this type of device? described in the patent EP0592375A1 where we try to solve the problem of the vibration of the pressure roller, above all because? the pressure does s? that paper particles tend to accumulate there.

The vibrating mass of the pressure rollers and the dynamic loads which are discharged on the counter-roller consequently lead to wear and damage to the reliefs of the pressure roller.

This ? a significant problem, above all in consideration of the cost of the pressure rollers and the incidence on production losses due to the replacement times of the elements.

The aforesaid patent, through the insertion of elastic rings under the pressure roller, reduces the aforesaid drawback but on condition that it foresees the use of single very narrow pressure elements, ie which have widths between 5 mm and 10 mm. In the event that pressure rollers must be used more? large circlips are not sufficient to compensate for the curvature of the counter roller and ensure uniform contact with it. In fact, the generator of the counter-roller becomes a curved line due to the effect of the pressure, while the pressure roller has an almost curved line. straight. Furthermore, when the pressed material remains adherent under the pressure roller of a certain width, this leads to the discharge of all the pressure force on a few points, exceeding the specific pressure that can be applied. withstand the material and consequently damaging the relief surface. This ? one of the most problems important and negative aspects related to the joining process by pressing of ribbon-like products such as paper.

The market often requires that the engraving of the pressure roller has, in addition to the function of joining multiple? ribbon-like products, a feature? of marking and decoration of the product and for this ? it is necessary that the pressure rollers reach widths of at least 150-200 mm. An example of this usage? in machines for the production of paper napkins, where a decoration is created on the single format of the napkin.

In the machines for the production of toilet paper and kitchen paper, two or more? paper veils are joined together with the addition of glues. In this case the process calls for glue dispensers to distribute the adhesive on the paper and a pressure roller, generally around 3 meters wide, which, by exerting pressure on the paper resting on a steel roller called the embosser, allows the glue itself to dry and make the gluing. In this case the pressure roller has a smooth surface and ? made with a rubber coating suitable for compensating differences in height of the tips of the embossing roller and thus ensuring a contact more? uniform as possible. A flaw for? some rubber? that of not transferring a high specific pressure, unless after a large deformation thereof which brings the pressure roller into contact with a greater portion of the surface of the embossing roller causing negative effects on the surface of the processed product. For this reason, smooth steel pressure rollers are often used which, to compensate for the bending due to the load, are mounted on bearings positioned inside them and with the presence of a central axis or long protruding pins, internally for the support of the bearings themselves . This mechanical construction can partially compensate for the non-uniformit? contact due to bending but does not solve the problem of thermal expansion of the material which alters the contact line between the two rollers, resulting in a system that is in any case not very efficient for the gluing function.

Another modality? of paper gluing, mainly used in the production of kitchen towel rolls, ? the so-called in jargon, tip-to-tip gluing, in which the pressure exerted between two embossing rollers is used, engraved on the surface so as to create protuberances of a truncated pyramid shape. Each of the aforementioned embossing rollers, after having deformed a relative veil of paper fed to it by means of pressure with rubber-coated rollers, transports the paper into contact with a wet glue roller so that a certain quantity? of glue remains on the paper in correspondence with the truncated pyramidal points, and finally, the two embossing rollers, which are in phase with each other, come into tangential contact in correspondence with the relative truncated pyramidal points. This process is very delicate and requires expensive and difficult mechanical machining of the rollers. AND? It is easy to understand that putting two rollers about 3 meters long in tangential contact only at the relative truncated-pyramidal tips requires a lot of precision, which ? influenced during the process by the bending of the roller structure and by the thermal expansion of the steel. However, small positioning inaccuracies cause lack of pressure between the points which generates a lack of gluing and therefore the production of unacceptable paper rolls.

SUMMARY OF THE INVENTION

Purpose of the present invention? that of realizing a pressure roller suitable for solving or limiting the problems highlighted above in the paper converting sector linked to the onset of vibrations in the pressure roller under the action of dynamic loads.

Other purpose? that of providing a pressure roller which, despite being rather large, can adapt to work correctly in cooperation with a counter-roller even when this ? deformed under load.

Other purpose? that of realizing a pressure roller which includes measures suitable for limiting the concentrated loads at the tips of the relative engraved surface caused by the concentrated accumulation of pressed material.

Other purpose? that of realizing a pressure roller in which the elastic reaction force of the surface of the roller can be differentiated in the width of the roller itself.

Other purpose? that of realizing a pressure roller which, in the event of partial damage to the reliefs engraved on the relative surface, can be quickly repaired by replacing only the damaged surface portions.

Other purpose? that of realizing a pressure roller, in particular suitable for working in cooperation with a counter-roller in paper converting machines, which is easy to produce and has low costs.

Other purpose? that of realizing a pressure roller suitable in particular for carrying out gluing operations on web materials by means of cooperation with a counter-roller which allows to maintain a uniform line of contact without being affected by bending or thermal expansion.

The purposes set out above and others still are achieved by means of a pressure roller of the type used in cooperation with at least one relative counter-roller in a pressure device provided for pressing web-like products in a machine for transforming material into web, said roller presser comprising a support ring on the outer surface of which ? mounted one or more? rubber elements above which ? mounted a pressure element of overall width substantially equal to the width of said pressure roller, the outer surface of said pressure element being adapted to cooperate with said counter-roller. The pressure roller of the invention is characterized by the fact that the pressure element is made up of a plurality of pressure rings, so that? the outer surface of said pressure elements arranged axially in succession to one another forms the outer surface of said pressure roller intended to cooperate with said counter-roller.

Further advantageous characteristics of the present invention are set forth in the dependent claims.

These and further advantages of the present invention will be better understood from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings, provided by way of example, but not to be considered in a limiting sense, in which:

Fig. 1 shows in a schematic side view an embodiment of a pressure device on which ? mounted a pressure roller according to the present invention to cooperate with a counter-roller in a machine for converting web products;

Fig. 2 shows a partial sectional view of the device of Fig. 1, taken along line II-II;

Figs. 3 and 4 show a detail of the section of Fig. 2 which represents the pressure roller of the present invention in two different operating configurations;

the Figs. 5 shows an embodiment of a decorative relief made by engraving the surface of a pressure roller according to the invention;

Fig. 6 shows, in a detailed view similar to that of Figs. 3 and 4, a different embodiment of a pressure roller according to the invention;

Figs. 7 and 8 show a detail of a component of a pressure roller according to the present invention according to the embodiment of Fig. 6 ,

Fig. 9 shows, in a detailed view similar to that of Figs. 3 and 4, a different embodiment of a pressure roller according to the invention;

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

With reference to Figures 1 and 2, in an embodiment of the present invention in an example of a pressure device, D, comprises a fixed support 4 rigidly connected to the structure, 5, of a machine for converting material into strip, n , which fixed support 4 keeps a mobile support 7 hinged through a shaft 3.

In this way the mobile support 7 has the possibility? to oscillate around the pin 3, by means of a pneumatic actuator, 6, shown here as a tubular element inflated by compressed air.

As can be seen in Fig. 2, on the mobile support 7 are mounted side by side a plurality of of pressure rollers, 1, each supported by a relative pin, 13 and relative bearings 11.

Each pressure roller 1 comprises a support ring, 10, on the outer surface of which housings are made for a plurality of of elastic elements 12 in the shape of a ring, arranged side by side in the axial direction with the aforesaid housings suitable for keeping the elastic elements 12 in a stable position. According to the known technique externally to the elastic elements 12? mounted a pressure element consisting of a tubular of overall width substantially equal to the width of said pressure roller 1, the outer surface of said pressure element being suitable for cooperating with a counter-roller 8. According to the present invention, on the other hand, the? pressure element? made up of a plurality of pressure rings 2, and on each ring-shaped elastic element 12, a relative pressure ring 2 being mounted (indicated individually according to the embodiments with the references from 2a to 2h) with an engraved outer surface to create a pressure with a specific design.

With reference also to Figs. 3, 4, 6, 7, 8 and 9, the pressure ring 2 has an internal diameter of a smaller size than the external diameter of the elastic element 12 so that the pressure ring 2 imposes a predetermined compression on the elastic ring which gives it a certain rigidity. Each pressure ring 2 has cavities, 21, 212, correspondingly formed in both base surfaces, 22, 23, and directed axially. In Fig. 1 ? shown an example of construction in which there are sixteen cavities? 21, 21? drill like holes, spaced 22.5? from each other. A connecting element, 9, 9?, made of an elastically yielding material ? suitable to fit into the cavities? 21 of two adjacent pressure rings 2 facing each other to connect them to each other preventing reciprocal rotation around the axis of the pressure roller 1, but allowing reciprocal sliding in the radial direction thanks to the fact that they are made of an elastically yielding material such as rubber.

In the embodiment shown in Figs. 3, 4 and 7 the cavities? 21 are through holes and the connection element 9 ? a pin that can? be of length substantially equal to the width of the pressure roller 1, or can? be more lengths, inserted through a respective hole of each of the pressure rings 2 to connect them together. In practice, each elastic element 9 passes through all the pressure rings 2a, 2b, 2c, 2d, 2e, 2f. Two containment flanges 14 connected by means of screws to the support ring 10 realize an axial containment of all the components described above of the pressure roller 1.

The operation of the embodiment of the present invention described above? immediately deducible from Figs. 3 and 4 where ? shown how the pressure rings 2 have the capacity? to adapt.

In particular, Fig. 3 shows the case in which, with respect to a distance X from the axis of rotation of the pressure roller 1, the pressure rings 2 are progressively misaligned by an amount? increasing to accommodate the deflection of a counter roller 8, caused by loading and thermal expansion. Thanks to the connection elements 9, all the pressure rings 2 can adapt to the deformation of the counter-roller 8 and at the same time remain in phase with each other in the angular direction in order to ensure continuity? between the designs of the engraving on their outer surface.

During the pressing process for joining two or more? ribbon products ? binding is the characteristic that the surfaces of the reliefs of the decoration engraved on the external surface of the pressure roller 1 and the surface of the counter-roller 8 mate with the utmost precision. AND? easy to understand that if in some points there is no contact with the same pressure you lose the capacity? to join the web products losing efficiency throughout the process.

In Fig. 4 ? shown is a case in which, during operation of the machine for converting the material into sliver, in correspondence with some pressure rings, 2c and 2d, ? remains a thickness of material, S, attached to the surface of the pressure roller 1. Thanks to the solution of the present invention the same pressure rings 2c and 2d can move radially by compressing the elastic elements 12 more. The load transmitted to the pressure roller 1 through the? unit? mobile 7 ? in this way it is kept distributed on all the pressure rings 2 avoiding discharging exclusively on the reduced surface of the few protrusions which are found in correspondence with the thickness and which would have led to the consequent crushing and damage thereof.

Fig. 5 represents a pressure roller 1 in which the surface ? engraved to create a dot decoration with a density? and a larger contact surface with the back-up roller 8 on some pressure rings 2a, 2g, compared to the other pressure rings 2b, 2c, 2d, 2e, 2f where the reliefs of the decoration have low density. AND? easy to guess that in a decorum of this type can not? there is an equal distribution of the specific pressure. Thanks to the present invention this drawback is advantageously solved by assembling elastic elements 12 with differentiated hardness. For example, in the embodiment shown in correspondence with the pressure rings 2a and 2g elastic elements 12 are mounted with a greater hardness than that of the other elastic rings in order to compensate for the greater specific pressure. Alternatively, the drawback is advantageously solved by providing pressure rings 2 with differentiated internal diameter. For example, in the configuration of Fig. 5 the pressure rings 2a and 2g are provided with a larger internal diameter? smaller than that of the other pressure rings to further compress the respective elastic element 12 and obtain the same result of a more elastic reaction? strong where needed.

Furthermore, a decoration such as that of Fig. 5 has portions which, due to their conformation, are more subject than others to collect processing residues and are therefore destined to have premature wear. Thanks to the present invention these interested parts can be replaced by continuing to use the other pressure rings which can have a longer life. long.

In Figs. 6 and 8 ? shown an embodiment of the present invention where the pressure rings 2? are provided with cavities?, 21?, drill corresponding blind holes on the two base surfaces 22 and 23. Pressure rings 2? adjacent are connected to each other by a connecting element 9? of a suitable shape to fit into the housing created by two cavities? 21? like facing blind holes. This suitable shape of the connecting element 9? can? be of various shapes such as spherical or ring-shaped. The cavities? 21?How do blind holes have in the case of the sphere, a diameter corresponding to that of the sphere itself which constitutes the connecting element 9? and a depth no greater than its radius. If a ring is used as a connecting element 9?, the external diameter of the ring will be? corresponding to the diameter of the cavity? 21? and the thickness of the ring greater than twice the depth measurement? of the cavity? 21?. In this way each pressure ring 2 has the possibility? to move radially under the thrust of the counter-roller 8 or due to a possible temporary accumulation of material, thanks to the elastic compliance of the connecting element 9?.

In this embodiment, the support ring 10? has a cylindrical external surface, while each pressure ring 2? internally provides a containment seat 25 for the relative elastic element 12, so that? the mounting of the pressure roller 1? ? simplified and ? It is possible to make very long pressure rollers.

Another advantage of the embodiment shown in Figs. 6 and 8 that the connecting element 9? presses against the bottom surface 26, of the cavities? 21? and therefore exerts a disengaging force between the pressure rings 2? adjacent, allowing a distance to be imposed between them which avoids their contact at the relative base surfaces 22, 23. The distance between the pressure rings 2? adjacent allows them to be able to assume inclined configurations thus improving? further their ability? to compensate for the differences in the load on the contact surface with the counter-roller 8 and also prevent the vibrations or frequent micro-movements from wearing their base surfaces 22, 23.

Connecting elements 9? are also provided between the pressure rings of the ends? 2?a 2?h and the flange 14?, so that? the latter has the function of both maintaining the angular phase between all the pressure rings 2? both to contain along the axis of the support ring 10? all pressure rings 2?. Is this a mutual distance between the pressure rings 2 established? by means of a certain compression of the connecting elements 9?.

A further embodiment of the present invention provides that the pressure rings 2, 2? are arranged in succession one adjacent to the other without there being any connecting element interposed between them. This simplified embodiment is useful when the pressure roller 1 has a smooth external steel surface, used for example for joining ribbon-like products after glue distribution and where it is not? the pressure rings must be angularly timed to each other.

Because of this ? otherwise? possible to insert the connecting elements 9? with a toroidal shape that acts only as a thickness placed between a pressure ring 2 and the other, without inserting itself in any cavity? 212, but having only the function of an elastic spacer to allow small angular movements of the pressure rings 2 themselves. The construction of the present invention for this application is in any case simple, allowing the pressure rings 2 to be advantageously independent in moving radially and angularly from each other, thus compensating push-ups and irregularities? of contact.

This last embodiment can? be advantageously used also in calendering processes, or pressing for the reduction of the thickness of the web material, where hardened steel rollers are used and ? crucial to maintain the? uniformity? of the pressure along the contact line between the pressure roller and the counter-roller. Advantageously the possibility? to create a subdivision of the pressure roller 1 by means of the composition of more? pressure rings 2 interrupts all the thrusts generated by deformations and/or thermal expansions that would have generated irregularities? on the nip of the pressing between two rollers.

In Fig. 9 ? shown a further embodiment of the pressure roller 1?? where is the support ring 10?? has the entire external surface covered with a single elastic element 12? which has a cylindrical external shape. A series of pressure rings 2?? which have an internal diameter slightly smaller than the external diameter of the elastic element 12?? they can be mounted on the latter in a sequential way and form the entire width of the pressure roller 1??. Between a pressure ring 2?? and the other can the connection elements 9 be interposed? as described in the previous examples, so that? the same pressure rings 2?? do they not touch on the base surfaces 22? and 23?, necessary to obtain a greater capacity? of adaptation. In this embodiment, the inner diameter of the pressure rings 2?? can? have a base of support more? tight on the elastic element 12?, for example with a rounded curved shape 25? to facilitate their assembly but above all to be far s? that they are more adaptable and therefore facilitate mobility? angular.

A further embodiment, even if not shown in the figures, consists of coating, in a stage subsequent to the entire assembly of the pressure roller 12, the whole outer surface of the pressure rings 2?, 2?? with a continuous shell, for example of a rigid but sufficiently yielding material such as a low thickness of hard rubber. Would this prevent a pressure roller 1 from appearing? with a surface with cracks, even if very small, between the base surfaces 22? and 23? of the pressure rings 2?, 2??. In this way the pressure roller 1?? with this constructive form it could be used in particular lamination applications where ? the pressure of an absolutely entire cylindrical surface is required.

The advantages of the present invention with respect to the prior art are evident. The pressure roller 1, 1? and 1?? can? conform to follow the deformation of the counter-roller 8 since each single pressure ring 2, 2?and 2?? realizes a short section of straight rigid contact that pu? adjust both its radial distance and its inclination with respect to the axis of the pressure roller 1, 1?.

Thanks to the presence of the connecting elements 9, 9?, the pressure rings 2, 2? and 2?? maintain the angular timing between them and therefore ? the alteration of the decorative pattern made on the outer surface of the pressure roller 1, 1? is prevented. At the same time each pressure ring 2, 2?and 2?? can? adapt to the surface of the counter-roller 8 whose geometry ? variable because of the variability? of the load and as a result of thermal expansion.

In a pressure roller 1, 1? according to the present invention the design of the decoration is made in sections, one for each pressure ring 2, 2? and 2?? which makes up the pressure roller.

During use, the vibrations triggered by the presence of any parts of material being processed which remain attached to the surface of the pressure roller will only affect the pressure rings 2, 2?and 2?? on which the material is attached, allowing the remaining pressure rings not to be damaged.

In the embodiments described, the connecting elements 9, 9? are cylinder pins 9 or balls 9?, or described as simple shims, and elements of a different shape could certainly be provided as long as? able to bring all the advantages described in the text.

Claims (11)

1. Pressure roller (1, 1?, 1??) of the type used in cooperation with at least one related counter-roller (8) in a pressure device (D) intended for pressing web-like products in a material transformation machine made of tape, said pressure roller (1, 1?, 1??) comprising a support ring (10, 10?, 10??) on the outer surface of which ? present at least one elastic element (12, 12?) on which ? mounted a pressure element of overall width substantially equal to the width of said pressure roller (1, 1?, 1??), the outer surface of said pressure element being suitable for cooperating with said counter-roller (8), said roller presser being characterized in that said pressure element ? made up of a plurality of pressure rings (2, 2?, 2??) mounted on at least one elastic element (12, 12?), so that? the outer surface of said pressure elements (2, 2?, 2??) arranged axially in succession one to the other, forms the outer surface of said pressure roller (1, 1?, 1??) intended to cooperate with said counter-roller (8). 2. Pressure roller (1?, 1??) according to claim 1 characterized in that between each of said pressure rings (2, 2?, 2??) ? interposed a connecting element (9?) made of elastically yielding material being suitable for resting on the facing surfaces (22, 23) of said two pressure rings (2?, 2??) to allow it to assume an independent inclination around the? axis of said pressure roller (1?, 1??) and allow a reciprocal displacement in the radial direction. 3. Pressure roller (1, 1?, 1??) according to claim 1 or 2 characterized in that each of said pressure rings (2, 2?, 2??) has cavities (21, 21?) obtained correspondingly in both base surfaces (22, 23) and directed axially, a connecting element (9, 9?) in elastically yielding material being suitable for being inserted into the cavities? (21, 21?) facing two adjacent pressure rings (2, 2?, 2??) to allow it to assume an independent inclination around the axis of said pressure roller (1?, 1??) and allow one reciprocal displacement in the radial direction. 4. Pressure roller (1, 1?, 1??) according to the previous claim characterized in that in said cavities? (21, 21?) ? inserted at least one connecting element (9, 9?) so as to connect the pressure rings (2, 2?, 2??) to each other, preventing their mutual rotation around the axis of said pressure roller (1, 1?, 1??) but allowing mutual sliding in the radial direction. 5. Pressure roller (1) according to the previous claim characterized in that said cavities? (21) are through holes and said connection element (9) ? a pin inserted through a respective hole of each of said pressure rings (2) to connect them together. 6. Pressure roller (1, 1?, 1??) according to claim 3 characterized in that said connecting elements (9?) have a cylindrical external dimension and said cavities? (21?) are blind holes with a diameter corresponding to that of the external cylindrical dimension which constitutes the connecting element (9?) and have a depth? not more than half of its thickness. 7. Pressure roller (1, 1?) according to one of the preceding claims, characterized in that said elastic elements (12) have differentiated hardness. 8. Pressure roller (1, 1?) according to one of the preceding claims characterized in that said pressure rings (2, 2?, 2??) have different internal diameters. 9. Pressure roller (1, 1?) according to one of the preceding claims, characterized in that each pressure ring (2?) internally provides a containment seat (25) for the relative elastic element (12). 10. Pressure roller (1, 1?) according to one of the preceding claims characterized in that the pressure rings (2, 2?, 2??) are mounted on an elastic shim (12?) which covers the entire pressure ring support 10?. 11. Pressure roller (1, 1?) according to one of the preceding claim characterized in that the pressure rings (2, 2?, 2??) have a contact surface with the elastic element (12?) more? narrow (25?) compared to their width.