FOLDING ROLLER WITH SEPARATELY MOUNTED CLAMPS

IN A INTERFOLDING MACHINE

Technical Field

[1] The present invention refers to the counter-rotating folding rollers group in a

machine for the transformation of paper, in particular a machine for the production of interfolded.

Background Art

[2] As known, there are numerous paper made articles, especially of the disposable type, such as paper towels, handkerchiefs, toilet paper or similar, which are sold in packaged sheets in such a way that a single pack is constituted by a plurality of individual sheets suitably folded and stacked one on the other in an interfolded mode.

[3] To obtain this type of products they are used machines called interfolding

machines in which there are a plurality of rollers arranged according to two distinct sequences each of which receives a strip of paper material, usually tissue, from which the sheets are obtained. The strip is first cut into sheets of suitable length and then conveyed toward a pair of counter-rotating folding rollers, each constituting the last roller of the above said rollers sequences. In correspondence with the folding rollers, the paper material sheets are folded and suitably overlapped in such a way that on a sheet coming from the first rollers sequence is partially overlapped a subsequent sheet coming from the second rollers sequence.

[4] At the exit of the folding rollers, the stacked and partially overlapped sheets are separated into default size bundles and then transferred to an unload unit.

[5] There are various types of counter-rotating folding rollers which have substantially the function of capturing the paper sheets and then selectively release them in such a way that during the capture a transverse folding line will be generated.

[6] Some types of conventional counter-rotating folding rollers are provided with ducts suitable to be placed in communication with suction members in such a way that the capture of the paper takes place thanks to the creation of vacuum on the surface of the rollers.

[7] Another type of conventional counter-rotating folding rollers selectively capture the sheets of paper due to the presence of mechanical parts. To this type belong the so- called folding rollers with clamp and wedge.

[8] Conventional folding rollers of the latter type are described in US Patent

2,468,254. Each of the folding rollers is provided on its surface with wedges angularly alternate with clamps. As clearly visible in figures 7 and 8 of the above said patent, when two overlapping sheets pass between the two rollers, the nose of the wedge, protruding from the relative roller surface, enters a slot on the opposed roller in which is placed a movable jaw which forms, together with the wall of the slot istelf, a clamp. In this way the wedge catches the two paper sheets and causes the curvature of a portion of them. Before the inlet of the wedge in the above said slot, the relative movable jaw is maintained in the release configuration via cam actuation elements that, mounted on the longitudinal end of the roller, act on a portion longitudinally projecting from the roller of the movable jaw. When the wedge exits the slot, the movable jaw is brought into the clamping position, thanks also to the action of springs which act on the movable jaw, thus tightening the edges of sheets that are caught in the clamp creating a transverse fold in the sheets.

[9] The main problem of this type of solution consists in the fact that the movable jaw, which is a single body longitudinally extending for the whole length of the folding roller, must be constructed with great accuracy as, to enable it to work correctly for the whole longitudinal extension of the paper sheets, the allowed dimensional tolerances are extremely small. In fact the conventionally adopted solution for ensuring the required dimensional tolerances is to mount the movable jaws in the relative roller, so that they work by removing chips around the whole roller with the already mounted clamps. Furthermore, with the conventional folding rollers above described, there are also problems of maintenance because even the damage of only a small longitudinal portion of a movable jaw involves the necessity of having to replace the whole movable jaw.

Summary of the invention

[10] The object of the present invention is to propose counter-rotating folding rollers for an interfolding machine so as to overcome the above noted problems of the prior art.

[11] More specifically, an object of the present invention is to propose a folding roller with limited production costs, in particular thanks to the fact that it is not necessary to perform chip removal treatment on the clamps after they are mounted on the roller.

[12] Another object of the present invention is to propose a folding roller of easy

maintenance.

[13] The above objects are achieved by a folding roller for interfolding machines as provided in claim 1.

[14] Conventionally, a folding roller with clamp and wedge for an interfolding machine provides peripherally first longitudinal grooves, angularly equidistant from each other, suitable to receive, in a radially sliding mode, catching wedges whose external end extends in a standby position from the roller surface, with the above mentioned wedges resiliently supported inside the relative grooves to radially move back, and peripherally comprising a same number of second longitudinal grooves, angularly equidistant from each other, alternate to the first longitudinal grooves, suitable to receive movable jaws mounted for swinging into the second grooves, between a clamping position, in which the movable jaw is arranged to interact with a corresponding fixed jaw made in a wall of said second groove, and a release position, in which the movable jaw is spaced from the fixed jaw and wherein, with the movable jaws, are associated elastic members arranged to press the movable jaw toward the clamping position.

[15] According to a characteristic aspect of the present invention a movable jaw

comprises a longitudinally elongated drive shaft that can be selectively rotated in step relation with the rotation of the folding roller between a clamping position of the movable jaw and a release position of the movable jaw, and a plurality of jaw elements mounted on the drive shaft, longitudinally aligned with one another.

[16] Advantageously, the movable jaw includes an automatic unlocking device suitable to allow a rotation of the jaw element towards the release position when the drive shaft is rotated into the clamping position of the movable jaw.

[17] A folding roller with clamp and wedge, as above outlined, allows to simplify the construction of the roller itself as it provides a plurality of independent jaw elements that do not need to be perfectly aligned with each other to work properly.

[18] Moreover, in case of damage, they can be replaced individual damaged jaw

elements without having to replace the whole movable jaw and above all without having to perform again mechanical treatment to restore the longitudinal linearity of the movable jaw.

Description Of Drawings

[19] These and other advantages associated with the folding roller for interfolding

machine of the invention will become, however, more easily understood through the illustration of an embodiment, non-limiting, as described below with the aid of the enclosed drawings, in which:

• Figure 1 shows a front view of a folding roller according to the invention;

• Figure 2 shows a view along the section line II-II in Fig.l;

• Figure 3 shows a detail of Fig.2;

• Figure 4 shows a front view of a component of the folding roller of Fig.1 ;

• Figure 5 shows a view along the section line V-V of Fig.4;

• Figure 6 shows a first perspective view of the component of Fig.4;

• Figure 7 shows a second perspective view of the component of Fig.4.

Detailed description of preferred embodiments

[20] With reference to the figures it is generally indicated with 10 a folding roller for an interfolding machine according to the present invention which comprises a substantially cylindrical body, 11, mounted on a shaft, 12, rotatably supported at both ends. The folding roller 10 is arranged to be mounted for rotating about its horizontal axis and opposite to an identical second folding roller. At the end of the shaft 12 are provided mechanical members, not shown, suitable for putting in step relation the rotation of the folding roller 10 with that one of the second identical counter-rotating roller. The cylindrical body 11 peripherally includes a plurality of radial slots, 13, arranged longitudinally equidistant, suitable to receive a corresponding plurality of folding fingers, not shown because of known art.

[21] The cylindrical body 11 also peripherally comprises first longitudinal grooves, 14, angularly equidistant from each other. More precisely, in the represented embodiment, the first longitudinal grooves are in number of four arranged at 90° one from the other, they longitudinally extend for the whole length of the cylindrical body 11 and have a depth greater than the radial slots 13. The first longitudinal grooves 14 are suitable to receive, for radially slide, catching wedges, 20, whose outer end extends in a standby position from the surface of the cylindrical body 11, with the above said wedges resiliency supported inside the relative grooves 14 in order to have the possibility to radially move back.

[22] Furthermore, the cylindrical body 11 peripherally comprises a same number of second longitudinal grooves, 15, angularly equidistant from each other, alternate to the first longitudinal grooves 14. More precisely, in the represented embodiment, the second longitudinal grooves 15 are four in number arranged at 90° one from the other. The second longitudinal grooves 15 are suitable to receive movable jaws, 30, mounted for swinging inside the second grooves 15.

[23] A third longitudinal groove is peripherally made between a first longitudinal

groove 14 and the subsequent second longitudinal groove 15 to allow the radial insertion of the catching wedges 20 and of the movable jaws 30. Shaped cover elements, 40, are associated via fastening members, 41, with the third longitudinal groove and have cylindrical external surface, 42, shaped to copy the outer surface of the cylindrical body 11. The shaped cover elements 40 extend in the second longitudinal groove 15 so as to prevent the exit of the movable jaws 30 and are shaped so as to form, on the side of the second longitudinal groove 15, an inclined wall that constitutes a fixed jaw, 43, suitable to interact with a jaw end, 31, of the movable jaw 30.

[24] The movable jaw 30 includes a drive shaft, 32, longitudinally elongated and a plurality of jaw elements, 33, mounted on the drive shaft 32 longitudinally aligned with each other. In the embodiment represented each jaw element 33 longitudinally extends for a length equal to the distance between two subsequent radial slots 13. The drive shaft 32 extends longitudinally from the end of the cylindrical body 11 so that, through appropriate motion transmission members located in correspondence of the ends of the shaft 12, not shown, the drive shaft 32 is selectively rotated, in step relation with the rotation of the folding roller 10, between a clamping position of the movable jaw 30, in which the jaw end 31 interacts with the fixed jaw 43, and a release position of the movable jaw 30 itself, in which the jaw end 31 and the fixed jaw 43 are spaced apart as shown in the figures. A motion transmission element, 34, is disposed between the drive shaft 32 and the jaw element 33 to transmit the oscillating movement of the drive shaft 32 to the jaw element 33.

[25] An automatic unlocking device, 35, is provided between the drive shaft 32 and the jaw element 33 in correspondence with the motion transmission element 34, suitable to allow a rotation of the jaw element 33 towards the release position when the drive shaft 32 is rotated into the clamping position of the movable jaw 30. [26] In the represented embodiment, the jaw element 33 is rotatably coupled to the drive shaft 32 and the motion transmission element 34 is constituted by a roller disposed rigid with the peripherally drive shaft 32 projecting from its surface that interacts with a cavity of the internal surface of the jaw element 33. The above said cavity of the jaw element 33 has a slotted shape so as to allow the rotation of the drive shaft 32 with respect to the jaw element 33 and thus constitutes the above mentioned automatic unlocking device 35.

[27] Two blind end seats, 36, of the jaw element 33 host an same number of elastic

members, 37, constituted, in the represented embodiment, by helical compression springs, which act between a side wall, 16, of the second longitudinal groove 15 and the jaw element 33 to press the movable jaw 30 towards the clamping position.

[28] When the drive shaft 32 is rotated in the release position, the motion transmission element 34 brings the jaw element 33 in the release position, overcoming the action of the elastic members 37. Subsequently, the drive shaft 32 returns to the clamping position but the rotation of the jaw element 33 towards the clamping position is controlled by the elastic members 37 thanks to the presence of the automatic unlocking device 35. Similarly, when the drive shaft 32 and the jaw element 33 are in the clamping position, thanks again to the presence of the automatic unlocking device 35, the jaw element 33 can be moved back to the release position by the presence of external forces acting on the jaw end 31, such as a jam of the sheets, fed to the folding roller 10, who overcome the action of the elastic members 37. In this way, the movable jaw 30 can return to the release position and therefore not to be damaged even when the drive shaft 32 is in the clamping position. Moreover, since the jaw element 33 is maintained in the clamping position only by the action of the elastic members 37, each of the jaw elements 33 is substantially independent from the others and the not perfect angular alignment is then automatically compensated for all the jaw elements 33 longitudinally aligned in the second longitudinal groove 15 and associated to a same drive shaft 32.

[29] Obviously, the shown and described embodiment is only an example and variations and modifications may be envisaged without departing from the inventive concept of the present invention.

[30] In fact, many variations can be made to the folding roller for interfolding machines of the present invention, by replacing the individual components with other functionally equivalent, remaining within the implementation of the inventive idea above described and within the scope of protection defined by the following claims.