CA2551795C - Double unwinder unit for rolls of sheet-like material provided with a device for splicing the sheets being unwound - Google Patents

Abstract

Unwinder unit for rolls (B1, B2) of sheet-like material (M), comprising a pair of unwinder shafts (1, 2) for respective rolls, arranged on opposite sides of a plane of symmetry (X) and suitable for feeding the material onto said plane and beyond it to an equipment downstream. The unit comprises a device (8) for splicing the tail end of a roll being unwound from one of said shafts to the leading end of a new, full roll installed on the other shaft, the device in turn having a configuration symmetrical to the plane of symmetry (S) and comprising a pair of splicing cylinders (11, 12), arranged on either side of the plane of symmetry (X), revolving around their respective axes and capable of moving closer together and further away from each other, the position in which they come closest coinciding with a condition of mutual contact; groups of suction holes (113) formed in lines along generatrices of the splicing cylinders (11, 12), for withholding the material against the cylinders and deviating it away from the plane of symmetry (X); first cutting means (13) for cooperating with the cylinders downstream of the area of mutual contact to cut the material withheld against the cylinder along a generatrix, second cutting means (24), arranged upstream; and means for controlling the cylinders, capable of synchronizing their rotation with the speed at which the material (M) is unwound.

Description

DOUBLE UNWINDER UNIT FOR ROLLS OF SHEET-LIKE MATERIAL
PROVIDED WITH A DEVICE FOR SPLICING THE SHEETS BEING UNWOUND
Field of the Invention The present invention refers to the field of equipment for unwinding rolls of sheet-like material, and particularly paper, tissue paper or the like. To be more precise, it concerns a double unwinder unit with a device for splicing the tail end of the material on a running out roll with the leading end of the material on a full roll.

Background of the Invention During the unwinding of rolls of flexible sheet-like material, e.g. paper, tissue paper and so on, it becomes necessary to replace run-out rolls with full ones.
Because it is obviously essential to reduce the down times involved in the roll-changing procedure, the known technique involves unwinding equipment capable of completing the procedure for setting up a new roll "in the background", using a symmetrical double unwinder shaft configuration. In practical terms, while one roll continues to be unwound on one shaft, the other shaft is offline and accessible for the installation of a second roll.
When the first roll becomes run-out, the second unwinder shaft starts to turn, while the run-out roll can be replaced with a full one on the first (now offline). Subsequent roll changes thus take place on either side in turn, so that a full roll is always readily available.
The double equipment of the type described above is also used to splice the tail end of the web on the roll running out to the leading end of the web on the new roll, so that the machines downstream of the unwinder (e.g. cutters, rewinders, folding apparatus, etc.) are fed with an uninterrupted flow of material, to the evident advantage of the production process. In case of paper, splicing is done by overlapping the two edges of material, the tail edge of the web on the roll running out and the leading edge of the web on the new roll, and compacting the two ends with the aid of a pressure exerted in a direction normal to the plane on which the edges lie.

In making the splice, the overlap between the two edges must not be too long, because this would be a waste of material and might interfere with subsequent processing operations. On the other hand, the strength of the splice is directly proportional to the longitudinal extension of the overlap, so said length must never drop below a certain limit.
The tail edge has to be kept in tension when the splice is made, so splicing has to be done when there is still a sufficient amount of material remaining to be unwound from the roll. So, together with the splicing action, it becomes necessary to provide for the detachment of the spliced end on the near-empty roll from the remainder of the web beyond it, by cutting the web crosswise. The cut edge has to be clean and neat, not only for aesthetic, but also for functional reasons, since an uneven edge can pose problems in subsequent processing stages and related machines. For the same reasons, the edge on the leading end of the new roll must be trimmed, again by means of a crosswise cut, before the actual splicing process can begin.
For obvious reasons, the splicing procedure needs to be as quick as possible, so that it induces a minimal slowdown in the delivery of the material being unwound. The splicing device must also be straightforward and structurally compact so as to avoid it interfering with the other parts of the equipment or with the material as it unwinds. The equipment based on the known technique does not fully satisfy the above-described requirements.

Summary of the Invention Illustrative embodiments may provide a double unwinder unit of the type previously described, which enables a clean splice of accurately-controllable longitudinal extension to be made at the utmost speed, by means of a structurally and functionally straightforward splicing device.
In accordance with one illustrative embodiment, there is provided an unwinder unit for rolls of sheet-like material. The unit includes a pair of unwinder shafts for respective rolls, lying on either side of a plane of symmetry of the unit in order to feed the material onto the plane of symmetry and beyond the same plane to equipment arranged downstream. The unit also includes a device for splicing a tail end of a running-out roll unwinding from one of the shafts, to a leading end of a new, full roll arranged on the other one of the shafts. The device has a symmetrical configuration with respect to the plane of symmetry and includes: a pair of splicing cylinders, arranged on opposite sides of the plane of symmetry, revolving around their own respective axes and displaceable close to and away from each other, the close position corresponding to a condition of mutual contact, with a certain degree of pressure, on the plane of symmetry; drive provisions for driving the rotation and the displacement of said cylinders; groups of aligned suction holes formed along respective generatrices of the cylinders, for retaining the material on the cylinders and deviating it away from the plane of symmetry; in each one of said cylinders, first cutting provisions cooperating with the cylinder, downstream of the area of contact with the other one of said cylinders, to transversely cut the material retained on the cylinder along a generatrix thereof, and second cutting provisions, arranged upstream, in turn for cutting the material transversely; and control provisions for controlling the drive provisions in order to synchronize the movement of the cylinders with the speed at which the material is unwound from the rolls.
The plane of symmetry may be substantially vertical, and may separate the unwinder shafts and the splicing cylinders of the splicing device, all of which may be arranged with horizontal axes. Deviating provisions may be provided to deviate the material in order to feed it into the device from above along the plane of symmetry, and then deviate it horizontally downstream of the device below one of the unwinder shafts.
The first cutting provisions may include, for each cylinder, a first cutter lying underneath the cylinder, radially pressing against it along a generatrix thereof. A deviating roller may cooperate tangentially with the cylinder to deviate the material released by the cylinder downstream of the first cutter away from the plane of symmetry.
Underneath the first cutter and the deviating roller, collector provisions may be arranged for collecting the material cut by the first cutter. The collector provisions may be removable from the unit.

The second cutting provisions may include, in each cylinder, a second cutter arranged above the cylinder for cutting the material in cooperation with a counter-cutting bar.
The second cutter may be arranged between two rollers of the deviating provisions, the rollers may include a main roller substantially tangent to the plane of symmetry and an auxiliary roller placed upstream, further away from the plane of symmetry.

The first and second cutting means may each include a cutting disc mounted slidingly on a guide extending along the corresponding cutting line of the material.
The suction holes may communicate with inner axial channels, which may be open at least at one axial end of the relevant cylinder in order to communicate with suction provisions that may be arranged externally. The opening of the channel may be obstructed by distributor provisions for timing the suction force in order to control the retaining/release of the material by the cylinder.
The distributor provisions may include at least one flange arranged at a shoulder face of the cylinder, and a distributor passage formed in the flange along an arc of the circular trajectory of said axial channels. The passage may communicate with the outside of the flange via a suction inlet for the suction provisions.
A separating screen may lie on the plane of symmetry in order to separate the two symmetrical parts of the splicing device above the splicing cylinders.
Working surfaces of the splicing cylinders may be slightly corrugated, so that longitudinal ridges may be generated in order to reduce the contact surface area when the cylinders come into contact with each other.
The second cutting provisions may be mounted according to an adjustably movable arrangement.

Brief Description of the Drawings The characteristics and advantages of the double unwinder unit according to the present invention for rolls of sheet-like material, provided with a device for splicing the rolls being unwound, will be apparent from the following description of its embodiments, provided purely as an illustrative and not restrictive example, with reference to the attached drawings, wherein:
figure 1 is a schematic front view of the unit according to the invention;
figure 2 is a cross section of the unit along line II-II of figure 1, with some parts omitted for the sake of clarity;
figures 3a to 3h show front views, as in figure 1 but enlarged, of the unit's splicing device in successive steps of the procedure for splicing the tail end of one web with the leading end of another;
figures 4 and 5 respectively show a longitudinal and axial view of a splicing cylinder of the splicing device according to the previous figures;

figure 6 is an axial view of a pneumatic distributor flange associated with the cylinder of figures 4 and 5; and figure 7 is a cross section of the flange in figure 6, in the plane indicated by the line VII-VII.

Detailed Description of the Preferred Embodiment Referring to figures 1 and 2, a unit according to the invention comprises a pair of unwinder shafts lying side by side 1, 2, revolvingly supported at one end by a frame 3 so that they lie parallel to one another on a horizontal plane. The rolls B1, B2 of paper web to be unwound are placed respectively on the shafts 1, 2. The tubes inside the rolls B1, B2 are inserted coaxially onto the shafts 1, 2 from their free end and fixed in place by means of known devices.
Equally known is the configuration of the unwinding drive means, represented in the case in point by two articulated arms 4, 5, hinged with one end to the frame 3, around respective horizontal axes. Each of the two arms 4, 5 comes over a corresponding shaft 1, 2 with a mirrored position with respect to the unit's vertical plane of symmetry, indicated by the letter X.
The structure of the arms 4, 5 is not described in detail, since - as already mentioned - it is well known and as such falling out of the scope of the present invention.
Suffice it to say that the material on the rolls 131, B2, is unwound by tangential contact of respective driving belts 4a, 5a, extending between sets of idler rollers 4b, 5b (two of which are motorized, one per belt) supported revolvingly by the arms 4, 5. The angular displacement of the latter around the hinged end is controlled by respective jacks 6, 7.
Clearly, the advantage of this solution is that there is no need to adjust the turning speed of the unwinding drive means, to keep a constant delivery rate of the material being unwound as the diameter of the roll gradually diminishes.
With particular reference to figure 1, the web of material M being unwound from the rolls, departing from them in a tangential direction, is fed towards the plane of symmetry X, and particularly towards a cutting and splicing device, globally indicated by the numeral 8, also comprising two parts that are mirrored to each other on either side of the plane X. The device 8, which will be described in more detail later on, is placed at a height slightly lower than the shafts 1, 2, and the web M arrives at its top end. After passing through the device 8 while lying on the plane X, and thus sliding vertically, the sheet M
exits from the bottom of the device and is brought by deviating rollers 9, into a horizontal position, near the floor, and thus leaves the unit sideways, heading for the equipment downstream in the process.

The core of the device 8 comprises two identical splicing cylinders, indicated as 11, 12, situated with their horizontal axis at the same height on either side of the plane of symmetry X. These cylinders are supported by a frame 10, shown in figure 2, so that they can not only turn around their own axis, but also move horizontally so as to come closer together or move further apart, the position in which they are closest to each other corresponding to a condition of mutual contact with some degree of pressure (i.e. they generate the pressure needed to ensure the adhesion of the two ends of web being spliced) on the plane of symmetry X. The mutual contact pressure can be advantageously increased by giving the two cylinders a working surface with slight circumferential corrugations. In practice, longitudinal ridges are created along the generatrices of the cylinders so as to give rise to a smaller contact surface area.
Again with particular reference to figure 2, the means for driving the rotation of the cylinders 11, 12 comprise, for instance, respective motors 26, 27 supported by the frame 3 and engaging with the ends of the cylinders by means of transmissions 28, 29. As will be explained in more detail hereinafter, these motors 26, 27 are capable of ensuring the rotation of the cylinders 11, 12 in synchronism with the speed of the webs being processed during the splicing stage. The translatory movement is induced by hydraulic actuators 30, incorporated in the frame 10 and engaging in their turn on the ends of the cylinders 11, 12.
Said drive components are schematically illustrated by way of example, since they can be realized using constructions that are obvious to any person skilled in the art.
The splicing cylinders 11, 12 can retain the paper material M on the working surface 11a, 12a by means of a vacuum system. In fact, with reference now also and in particular to figures 4 to 7, regarding the cylinder 11 (the cylinder 12 being identical), the working surface 11a has a distribution of suction holes 113 arranged along a number of equally spaced generatrices (four in the example). The passage of a pneumatic flow is achieved through channels 114 formed axially in the cylinder, in a off-centered position, so that they extend underneath along respective rows of holes 113. The channels 114 are open at the ends on the two shoulder faces 11b of the cylinder. The corresponding holes and channels on the cylinder 12 can be seen, albeit with no numerical reference for the sake of clarity, in figure 1 and in figures 3a to 3h, which will be considered later on.

The suction exerted through the holes 113 in the cylinders 11 and 12 is suitably timed, using a system known as such, so that the material M is retained through a given angle of rotation, whereas it is released for the remaining angle, according to the required control timing. For this purpose, the shoulder faces of the cylinders are closed between two fixed timing flanges, one of which is schematically illustrated in figures 6 and 7, indicated by the numeral 115.

The flange 115, provided with a central hole 115a to allow for the passage of the core of the corresponding cylinder 11, intercepts the open ends of the corresponding channels 114. Along the circular trajectory defined by said channels, however, a distributor passage 115b is formed in the inner face of the flange 115, i.e. the one in contact with the shoulder face of the cylinder. The passage 115b consists of a blind arc-shaped notch whose width substantially coincides with the diameter of the channels 114.
An axial passage 115c places the distributor passage 115b in pneumatic communication with the outside, where a suction inlet (not illustrated) is arranged. The distributor passage 115b thus opens the channels on the outside and the suction action is only established along a given arc of trajectory, the length of which is thus determined by the circumferential extension of the arc-shaped notch. For the remainder of the arc of rotation, on the other hand, the channels will be obstructed by the flange 115, so there will be no suction action.
Returning now to figure 1, the splicing cylinders 11, 12 cooperate with respective first cutters 13, 14, arranged underneath the cylinders, and consequently downstream of the splicing area. The first cutters 13, 14 are only schematically represented in figure 1, while the characteristics that exemplify one of them (i.e. the cutter 13 associated with the cylinder 11) are shown in more detail in figures 4 and 5. It can be noticed in particular that the cutter 13 can be realized with a cutting disc 13a mounted slidingly and driven by a motor (not shown) on a guide 13b lying along a generatrix of the cylinder 11. Following the axial movement of the disc, which comes up against the working surface of the corresponding cylinder, the web M is scored and cut along a generatrix corresponding to a line crosswise to the web.

Idler rollers 15, 16 cooperating tangentially with the cylinders 11, 12 are arranged underneath the cylinders 11, 12 and alongside the first cutters 13, 14, displaced further away from the plane of symmetry X. Two boxes 17, 18 for collecting the material M are arranged immediately beneath the idler rollers 15, 16.
Upstream of the cylinders 11, 12, i.e. above them, the device 8 is completed by a separating screen 19 lying on the plane of symmetry X and by a pair of deviating rollers 20, 21, that are mirrored to each other and assisted by auxiliary rollers 22, 23, to deviate the web M from the plane on which it leaves the corresponding roll to the plane of symmetry X. Finally, there are second cutters 24, 25 (referring again to figure 1), which are operated to cut the web material M along crosswise cutting lines immediately upstream of the deviating rollers 22, 23. The second cutters 24, 25 are entirely similar to the first cutters 13, 14, except that they cooperate not with the cylinders 11, 12, but with specific respective counter-cutting bars 31, 32.

The unit is controlled by means of a control system that is not illustrated or described in detail here because its configuration is self-evident, given the functional description provided below.
With reference now specifically to figures 3a to 3h, as well as to figure 1, the unit according to the present invention works in the following manner. In figure 1, a roll 131 is unwinding normally on the shaft 1, with the material M that, as explained above, passes through the device 8 to exit sideways underneath it, downstream of the deviating rollers 9.
The two splicing cylinders 11, 12 are both at a standstill in a withdrawn position, furthest away from each other, where they do not interfere with the passing of the material as it unwinds. The other shaft 2 is free and accessible for the setup of a full roll B2, that will need to be spliced to the roll 131, so that the roll B2 can replace the roll B1 in the unwinding process when the latter becomes run-out.
In figure 3a, the roll B2 has thus been set up on the shaft 2 and the leading end of the sheet of material M2 has been inserted in the device 8, between the deviating roller 21 and the separation screen 19, up until the edge of said leading end has been taken up by the suction system on the corresponding splicing cylinder 12. In the meantime, the material MI
unwinding from the roll 131 continues to slide vertically, with the screen 19 that physically separates the two material feedings, thereby avoiding any risk of interference between them.
At this point, via the control system, the splice is prepared by unwinding the roll B2 on low speed (figure 3b). In this phase, the drive belt 5a, and consequently also the web on the roll B2, obviously move in synchronism with the splicing cylinder 12.
The material M2 is withheld by the suction force against the cylinder 12 over a certain arc of rotation, then it is released to engage with the idler roller 16, according to the timing established by the distributors 115b of the fixed flanges 115, and thus unloaded and collected to a certain amount in the collection box 18 underneath, until the perfect alignment of the web is achieved and any imperfections in the material are eliminated.
Figure 3c shows the very next stage: when the forward feed stops, the cylinder is positioned with the suction holes exactly in phase with the cutter 14, which has been used to perform a crosswise cut, thus providing the material M2 with a clean, neat edge that is held against the cylinder by the suction holes. The fact that the suction force, and thus the.
adhesion to the cylinder, takes effect right along said edge enables its position to be controlled extremely precisely. The resulting scrap S remains in the box 18, from where it can subsequently be taken away. The cylinder 12, still kept in synchronism with the rotation of the roll B2, is turned in reverse, raising back the cut edge of the end of sheet, which is still held in place by the suction system, up to the exact height of the axes of the cylinders (figure 3d).
During the above-described procedure for preparing the leading end of the roll B2, the roll 131 has continued to unwind undisturbed. When it is nearly run out, as shown in figure 3e, the unwinding is stopped and the actual splicing step takes place between the leading end of the material M2 on the full roll B2, and the material M1 on the roll 131. The two splicing cylinders 12 and 13 are moved into mutual contact, where they generate the pressure needed to join the two webs of material together.

Now the cutter 24 upstream of the splicing cylinders takes action on the material M1 on the roll 131, making a crosswise cut (figure 3f). The tail end of the sheet on the roll 131 thus also has a clean, neat edge. The splicing cylinders start to turn again, at a controlled pace in synchronism with the speed of the full roll B2. The splice is completed when the edge of the tail end M1 passes beyond the splicing cylinders (figure 3g). Said cylinders then move back into the position where they are furthest away from each other (figure 3f) and stop turning, thus returning to the initial situation with the material sliding smoothly and freely, this time from the full roll B2. The shaft 1 is now ready for loading a new roll as soon as the empty tube (with any material left on it) has been removed.
The whole above-described procedure can be repeated in exactly the same way, but on opposite sides of the unit. Thanks to the perfectly symmetrical arrangement of the unit, and of the splicing device 8 in particular, the leading end of a full roll will be prepared alternately on one side and the tail end of the roll running out will be cut on the other.
The unit according to the present invention primarily enables the longitudinal extension of the splice to be accurately controlled, since its length is determined by the distance, measured along the trajectory of the web, between the splicing cylinders 11, 12 and one or other of the cutters 24, 25 upstream. According to a possible embodiment, said distance may be varied by means of a displaceable mounting of the cutters 24, 25, to adapt the dimensions of the splice as the case may be.

Another advantage of the unit according to the invention lies in the opportunity to realize both the cut edges of the spliced ends with the utmost neatness and precision, and thus avoid problems in subsequent processing stages and related machines. In particular, the leading end of the full roll can be trimmed with a minimal waste of material, thanks to the preparatory procedure being controlled by the transport induced by the suction force exerted by the splicing cylinders 11, 12.
The cutting and splicing procedure also features few, elementary operational steps, so it can be done quickly, inducing a scarcely significant slow down in the feed rate of the web being unwound. The preparation and cutting of the material, controlled automatically by means of the suction system, can cope with even very wide and soft materials, as may be necessary particularly in the tissue paper field. Finally, the straightforward and compact design of the splicing device makes it very economical, even from the maintenance standpoint, and when it is not in use it does not interfere in any way with the normal unwinding of the material.
Variations and/or modifications can be made to the double unwinder unit for rolls of sheet-like material with a device for splicing the rolls as they unwind according to the present invention, without thereby departing from the scope of the invention itself.

Claims (12)

1. Unwinder unit for rolls of sheet-like material, comprising a pair of unwinder shafts for respective rolls, lying on either side of a plane of symmetry of the unit in order to feed said material onto said plane of symmetry and beyond the same plane to equipment arranged downstream, said unit also comprising a device for splicing a tail end of a running-out roll unwinding from one of said shafts, to a leading end of a new, full roll arranged on the other one of said shafts, said device having a symmetrical configuration with respect to said plane of symmetry and comprising:

a pair of splicing cylinders, arranged on opposite sides of said plane of symmetry, revolving around their own respective axes and displaceable close to and away from each other, the close position corresponding to a condition of mutual contact, with a certain degree of pressure, on said plane of symmetry;

drive means for driving the rotation and the displacement of said cylinders;

groups of aligned suction holes formed along respective generatrices of said cylinders, for retaining said material on the cylinders and deviating it away from said plane of symmetry;

in each one of said cylinders, first cutting means cooperating with the cylinder, downstream of the area of contact with the other one of said cylinders, to transversely cut the material retained on the cylinder along a generatrix thereof, and second cutting means, arranged upstream, in turn for cutting said material transversely; and control means for controlling said drive means in order to synchronize the movement of the cylinders with the speed at which said material is unwound from said rolls.

2. The unit according to claim 1, wherein said plane of symmetry is substantially vertical, separating said unwinder shafts and the splicing cylinders of said splicing device, all of which arranged with horizontal axes, deviating means being provided to deviate said material in order to feed it into said device from above along said plane of symmetry, and then deviate it horizontally downstream of the device below one of said unwinder shafts.

3. The unit according to claim 2, wherein said first cutting means include, for each cylinder, a first cutter lying underneath the cylinder, radially pressing against it along a generatrix thereof, a deviating roller cooperating tangentially with said cylinder to deviate the material released by the cylinder downstream of said first cutter away from said plane of symmetry.

4. The unit according to claim 3, wherein, underneath said first cutter and said deviating roller, collector means are arranged for collecting the material cut by the first cutter, said collector means being removable from the unit.

5. The unit according to any one of claims 2 to 4, wherein said second cutting means comprise, in each cylinder, a second cutter arranged above the cylinder for cutting said material in cooperation with a counter-cutting bar.

6. The unit according to claim 5, wherein said second cutter is arranged between two rollers of said deviating means, said rollers comprising a main roller substantially tangent to said plane of symmetry and an auxiliary roller placed upstream, further away from said plane of symmetry.

7. The unit according to any one of claims 2 to 6, wherein said first and second cutting means each comprise a cutting disc mounted slidingly on a guide extending along the corresponding cutting line of the material.

8. The unit according to any one of claims 1 to 7, wherein said suction holes communicate with inner axial channels, which are open at least at one axial end of the relevant cylinder in order to communicate with suction means arranged externally, the opening of said channel being obstructed by distributor means for timing the suction force in order to control the retaining/release of the material by the cylinder.

9. The unit according to claim 8, wherein said distributor means comprise at least one flange arranged at a shoulder face of the cylinder, and a distributor passage formed in said flange along an arc of the circular trajectory of said axial channels, said passage communicating with the outside of the flange via a suction inlet for said suction means.

10. The unit according to any one of claims 1 to 9, wherein a separating screen lies on said plane of symmetry in order to separate the two symmetrical parts of said splicing device above said splicing cylinders.

11. The unit according to any one of claims 1 to 10, wherein working surfaces of said splicing cylinders are slightly corrugated, so that longitudinal ridges are generated in order to reduce the contact surface area when the cylinders come into contact with each other.

12. The unit according to any one of claims 1 to 11, wherein said second cutting means are mounted according to an adjustably movable arrangement.