WO2019215575A1

WO2019215575A1 - Suction roller structure for interfolding machines

Info

Publication number: WO2019215575A1
Application number: PCT/IB2019/053678
Authority: WO
Inventors: Giuseppe Lupi; Angelo Torri; Gianluca Giometti
Original assignee: United Converting Srl
Priority date: 2018-05-07
Filing date: 2019-05-06
Publication date: 2019-11-14
Also published as: EP3781506B1; IT201800005097A1; EP3781506A1

Abstract

Suction roller structure for the pneumatic transport of sheets in an interfolding unit (U), comprising a suction source (2) comprising an inner cavity of an inner hollow cylinder (1) and an outer roller (3) provided with longitudinal rows of bores (4) angularly spaced and selectively communicating with said suction source during the angular rotation of the roller (3) with respect to the cylinder (1).

Description

SUCTION ROLLER STRUCTURE FOR INTERFOLDING MACHINES

Technical Field of the Invention

The invention relates to a suction roller to pneumatically transport sheets of paper, especially the type of suction roller used in operating units intended for cutting and/or folding interfolded sheets of paper, i.e. stacked folded sheets, in such a way as to obtain a partial overlapping of the adjacent edges of the sheets. This kind of arrangement is used, for example, to manufacture packs of stacked napkins in such a way that upon extracting the napkin in the extraction position, one flap of the underlying napkin is automatically lifted, in such a way as to ease the extraction of the following napkin.

This type of arrangement may be used for toilet paper, face tissues and more. Background art

It is known that interfolding machines are equipped with a couple of juxtaposed and counter-rotating rollers, through which the sheets of paper to be folded/cut are fed.

Depending on the task that must be performed, cutting blades or projections may be present on the surfaces of one of the rollers and, on the opposite roller, there are corresponding slots which rotate in line with the blades/projections so as to have the processed sheet of paper cut or folded.

Once folding is performed, the sheets of paper are moved to an underlying device, which is known as a“stacker”, which forms numerical stacks of sheets and works in line with the rotation of rollers.

During the operations, rollers must also perform the task of keeping the sheets adhering to the outer surface.

To this end, the rollers of the interfolding units are equipped with bores connected to a suction system, which can be laterally or centrally mounted with respect to the roller.

From WO2017168232, in the name of the same applicant, a suction roller structure is known for interfolding units, which provides a distribution of pneumatic valves interposed between a permanent vacuum source and the external suction bores of the roller, also with cams arranged to open one or more valves at one or more angular positions taken by the roller. This solution has solved the problems and the drawbacks of the previous known systems but provides for the use of relatively complex pneumatic valves. Therefore, there is the need for an efficient suction roller, flexible in use and having a simplified construction.

Object of the Invention

The present invention is intended to provide a suction roller to be used with interfolding units, which allows to overcome the drawbacks of the already known solutions.

According to the invention, the object is achieved by using a suction roller for interfolding units according to the main claim.

Further technical objects and advantages are achieved by units according to the dependent claims.

Summary of the Invention

A first advantage is that the suction roller of the invention allows the operator to select the arrangement and succession of the external suction bores in a simple and reliable way, with a simplified construction with respect to systems of the known type.

A second advantage is that the suction system can be adapted if the format of the processed sheets of paper is changed.

List of Drawings

These and other advantages will be better understood by anyone skilled in the art from the description below and the accompanying drawings, given as a non limiting example, wherein:

- Fig. 1 schematically shows a front view of a suction roller for an interfolding unit according to the invention;

- Figg. 1 b, c, d respectively show the roller of Fig.1 in B-B, C-C and D-D section;

- Fig. 2 shows the roller of Fig. 1 in an A-A section;

- Fig. 3 shows the detail F of Fig. 3;

- Fig. 4 shows a perspective view of the roller of Fig. 1 in a partial longitudinal section;

- Fig. 5 schematically shows an interfolding machine equipped with suction rollers according to the invention. Detailed Description

With reference to the attached drawings, described herein is a preferred embodiment of a suction roller structure for pneumatically transporting sheets in a U-shaped interfolding unit.

The structure comprises a permanent suction source 2 comprising the inner cavity of an inner hollow cylinder 1.

Around the inner hollow cylinder 1 an outer hollow roller 3 preferably mounted on bearings 22 carried by a flange 23 supporting the ends of the roller 3 and which is provided with longitudinal rows of bores 4 angularly spaced and selectively communicating with said suction source during the angular rotation of the roller 3 with respect to the cylinder 1 can rotate.

The selective communication between bores 4 and source 2 is carried out thanks to a distribution of intermediate suction chambers 7 that communicate and are associated with corresponding longitudinal rows of bores 4, and preferably consisting of longitudinal bores made in the thickness of the roller 3. According to the invention, a longitudinal distribution of cylindrical sleeves 6 keyed onto the aspirated hollow cylinder 1 and provided with a continuous surface 12 and at least one radial opening 8 communicating with the cavity 2 through bores or openings 19 and a longitudinal distribution of feelers 5 mounted internally to the outer roller 3 in a position corresponding to respective sleeves 6 integrally movable to it and provided, in turn, with a radial bore 9 communicating externally with a corresponding intermediate chamber 7 are provided. The feelers 5 are also provided, at the inner end, with an opening 10 capable of sealingly slide on the cylindrical surface of a respective sleeve 6 such that during the rotation of the roller 3 the opening 10 alternately passes from a suction position when in correspondence of said radial opening 8 to a non-suction position when in correspondence of said continuous 12.

Preferably, the feelers 5 are radially movable on radial pins 20 and are kept in contact with the surface 12 of the sleeve 6 by means of thrust springs 15 which operate between the outer roller 3 and the corresponding feelers 5.

In the illustrated embodiment, the outer roller 3 comprising a longitudinal distribution of blocks 13 realised in the form of preferably movable portions of the roller 3 comprising a number of external radial bores 4’, communicating with a longitudinal bore 7’ which, in the mounting position, is arranged in continuity with a respective intermediate chamber 7, and it is provided with an inner radial opening 14 which communicates with the radial bore 9 of the feeler 5.

Preferably, at least one block 13 is mounted in a removable way by the jacket 26 of the roller 3 e.g. by means of externally accessible screws 25.

Advantageously, the movability of the blocks 13 allow an access inside the outer roller 3, e.g. to inspect the cavity 27 of the roller 3 or to maintain or replace an inner element such as the feelers 5 or the springs 15.

More generally, a suction roller structure for the pneumatic transport of sheets in an interfolding unit comprising an inner suction source and an outer hollow roller provided with longitudinal rows of bores selectively communicating with the suction source during the angular rotation of the roller has been found to be advantageous, wherein the roller has at least one block in the form of a portion of the roller in continuity with the outer cylindrical surface thereof, wherein the block is removable to inspect the roller cavity.

In this embodiment, the thrust springs 15 are arranged between the blocks 13 and the corresponding radially movable feelers 5, to keep the opening 10 sealed on the surface 12 of the respective sleeve 6.

In the described example, the sleeves 6 are keyed on an inner hollow cylinder 1 inside a gap 17 interposed between the inner hollow cylinder 1 and the outer roller 3, and the inner hollow cylinder 1 is provided with radial bores 16 which put in communication the cavity 2 with the gap 17 which, in turn, communicates with the opening 8 of the sleeve 6 through longitudinal bores 21 of the sleeve. Advantageously, an angularly offset mounting is provided on the inner hollow cylinder 1 of some sleeves 6 intended for suctioning rows of bores 4 corresponding to an initial or final flap of a sheet being processed in the interfolding unit and other sleeves 6 intended for suctioning rows of bores 4 corresponding to a median portion of the sheet.

With this solution also the respective radial openings 8 of the sleeves, possibly made of different angular amplitudes, are angularly offset and allow the suction of the sheets to be managed at different points according to the angular position taken by the outer roller.

With reference to Fig. 5, preferably, the roller 3 is a folding roller of the type used in pairs in interfolding machines to fold successions of sheets 7a, 7b at a common tangency point Z, in order to create stacks of interfolded sheets S in combination with detachment elements M that detach the sheet from the rollers. To this end, the roller 3 may be equipped with a grooved outer surface 22 that transports the sheets and towards which the bores 4 are faced.

The operation of an interfolding machine is generally known and, therefore, it is not described in greater detail.

The structure of the invention is therefore composed of the following main components:

a central suction cylinder or tube 1 suitably perforated in the central zone 2 to bring the vacuum inside the roller, wherein the suction is preferably carried out by connecting the suction ducts going towards a vacuum pump to the ends of the tube;

an outer roller 3 having radial bores 4 arranged on different longitudinal rows and which intercept the suction chambers 7 which, in turn, consist of longitudinal bores made in the thickness of the roller. During use, certain rows of bores will realise the suction of the heads and tails of the folded sheets from the interfolding unit U, while the other rows of bores will suck near the centreline of the sheet;

a certain number of (optional) blocks 13 which are inserted into suitable compartments formed radially in the roller 3, which restore the integrity of the outer roller itself and are characterized by a bore 7', which it traverses longitudinally, which restores the continuity of the longitudinal bores 7 or intermediate suction chambers of the roller;

elastic elements 15 (e.g. Belleville washers) interposed between the block 13 and the feeler 5;

the feelers 5, preferably constituted each by a single piece of particular material suitable for sliding, which are geometrically integrated within the blocks 13 and which have a through bore 9 in the central part for the passage of air; the central sleeves 6, made of a cylindrical element keyed on the suction tube 1 with a circular opening 8 on it which allows the passage of the vacuum. During operation, the internal suction axis or cylinder 1 also constitutes the fixed axis around which the outer roller 3 rotates. Together with the outer roller 3 the systems formed by block 13, feeler 5 and thrust spring 15 will rotate.

During the rotation of the roller 3, the feelers 5 slide on the central sleeves 6, when the feeler passes over the opening 8 of the central sleeve, communication between the vacuum chamber 2 (which is represented by the whole volume between the suction tube and the inner surface of the roller jacket) and the intermediate longitudinal bores 7 formed in the roller, towards which all the rows of radial bores 4 of the roller itself are faced, takes place by means of the through bore 9 of the feeler 5.

The communication between the inner chamber of the vacuum 2 and the intermediate ducts 7 is therefore implemented for a certain angle for each revolution of the roller 3, depending on the geometry of the opening 8 formed in the central sleeve 6.

The sleeves 6 which feed the rows of bores 4 of the heads and tails of the leaflets will have a circular opening having position and width different from the central sleeves which feed the bores of the centrelines of the leaflets, to allow the exchange mechanism of the leaflets between the folding and transporting rollers of the same from the cutting roller to the folding roller, according to a mechanism of the known type to realise the folding of the sheets.

The present invention has been described according to preferred embodiments, but equivalent variants can be designed without departing from the agreed scope of protection.

Claims

1. Suction roller structure to pneumatically transport sheets into an interfolding unit (U) comprising

a suction source (2) comprising an inner cavity of an inner hollow cylinder (1 ),

an external roller (3) provided with longitudinal rows of bores (4) angularly spaced and selectively communicating with said suction source during the angular rotation of the roller (3) with respect to the cylinder (1 ),

a distribution of intermediate suction chambers (7) that communicate and are associated with corresponding longitudinal rows of bores,

characterized in that it comprises

a longitudinal distribution of cylindrical sleeves (6) keyed onto the aspirated hollow cylinder (1 ) and provided with an outer surface (12) and at least one radial opening (8) communicating with the cavity (2)

a longitudinal distribution of feelers (5) mounted internally to the outer roller (3) in a position corresponding to respective sleeves (6) and provided with a radial bore (9) communicating externally with a corresponding intermediate chamber (7) and also provided, at the inner end, with an opening (10) capable of sealingly slide on the cylindrical surface of a respective sleeve (6) such that during the rotation of the roller (3) the opening (10) alternately passes from a suction position when in correspondence of said radial opening (8) to a non suction position when in correspondence of a continuous portion of said outer surface (12).

2. Structure according to claim 1 , wherein said intermediate chambers (7) consist of longitudinal bores in the thickness of the outer roller (3).

3. Structure according to claim 1 or 2, comprising a distribution of thrust springs (15) arranged between the outer roller (3) and corresponding radially movable feelers (8) to keep said opening (10) sealed on the surface (12) of a respective sleeve (6).

4. Structure according to one of the preceding claims, comprising a longitudinal distribution of blocks (13) in the form of portions of the roller (3) comprising a number of external radial bores (4’), communicating with a longitudinal bore (7’) arranged in continuity with a respective intermediate chamber (7), and provided with an inner opening (14) communicating with the radial bore (9) of the feeler (8).

5. Structure according to claim 4, wherein at least one block (13) is mounted in a removable way with respect to the roller (3).

6. Structure according to claim 4 or 5, comprising a distribution of thrust springs (15) arranged between said blocks (13) and corresponding feelers (8) radially movable to keep said opening (10) sealed on the surface (12) of a respective sleeve (6).

7. Structure according to one of the preceding claims, wherein said opening (8) of said sleeves (6) communicates with the cavity (2) of the hollow cylinder (1 ) through radial bores (19) of the hollow cylinder (1 ).

8. Structure according to one of the preceding claims, wherein said opening (8) of said sleeves (6) communicates with the cavity (2) of the hollow cylinder (1 ) through longitudinal bores (21 ) of the sleeve communicating with a gap (17) interposed between said hollow cylinder (1 ) and said outer roller (3) and communicating in turn with the cavity (2) through bores (16) of the hollow cylinder (1 ).

9. Structure according to one of the preceding claims, comprising at least one first sleeve (6) designed to arrange the suction of rows of bores (4) corresponding to an initial or final flap of a sheet being processed in the interfolding unit and at least a second sleeve (6) designed to arrange the suction of rows of bores (4) corresponding to a median portion of the sheet, said first and second sleeve being provided with respective radial openings (8) angularly offset by amplitude and / or position.

10. Structure according to one of the preceding claims, wherein at least one of said feelers (5) is movable radially guided on radial pins (20).

1 1. Interfolding unit comprising a pair of folding rollers (3s, 3d) arranged side by side and counter-rotating to operate at a common tangency point (z) on successions of sheets fed according to a staggered position between the two rollers, characterized in that at least one folding roller is a roller (3) according to one or more of the preceding claims.