WO2005051817A1

WO2005051817A1 - Double unwinder unit for rolls of sheet-like material provided with a device for splicing the sheets being unwound

Info

Publication number: WO2005051817A1
Application number: PCT/IT2004/000653
Authority: WO
Inventors: Tommasi Renzo
Original assignee: Rent S.R.L.
Priority date: 2003-11-28
Filing date: 2004-11-25
Publication date: 2005-06-09
Also published as: HRP20110422T1; RS51997B; RU2006123021A; EP1694592B1; RU2372270C2; CA2551795C; CA2551795A1; ES2363275T3; PL1694592T3; DK1694592T3; ATE501074T1; PT1694592E; EP1694592A1; ITFI20030301A1; DE602004031761D1; SI1694592T1; EP1694592B8

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 DESCRIPTION

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. f [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

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. I The splicing device must also be straightforward and Istructurally 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 The fundamental object of the present invention is thus to provide a double unwinder unit of the type0j 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. This object is achieved by the double unwinder unit5 according to the present invention, the essential characteristics of which are defined in the first of the attached claims. Brief description of the drawings The characteristics and advantages of the double0J 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,5 |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 ofQ¹ clarity; figures 3a to 3h show front views, as in figure 1 S Ibut enlarged, of the unit's splicing device in successive

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 Bl, B2 , is unwound by tangential contact of irrespective driving belts 4a, 5a, extending between sets of

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

t lιhrough channels 114 forme ^"d a ⁷xia ^"lly in the cylinder, in a

Igiven arc of trajectory, the length of which is thus

to the plane of symmetry X. Finally, there are second

In the meantime, the material Ml unwinding from the roll

]31 continues to slide vertically, with the screen 19 that physically separates the two material feedings, thereby avoiding any risk of interference between them.

I 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 12 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 Bl 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 Ml on the roll Bl . 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 Ml on the roll Bl, making a crosswise cut (figure 3f) . The tail end of the sheet on the roll Bl 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 Ml passes beyond the splicing cylinders (figure 3g) . Said cylinders then move back into the position where they are furthest laway 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 jone side and the tail end of the roll running out will be cut on the other. The unit according to the present invention

to the present invention, without thereby departing from

Ithe scope of the invention itself.

Claims

CLAIMS L. Unwinder unit for rolls (Bl, B2) of sheet-like material, comprising a pair of unwinder shafts (1, 2) for _< respective rolls, lying on either side of a plane of jl [symmetry (X) of the unit in order to feed said material Dnto said plane of symmetry (X) and beyond the same plane to equipment arranged downstream, said unit also comprising a device (8) for splicing a tail end of a running-out roll (Bl) unwinding from one of said shafts ι(l) , to a leading end of a new, full roll (B2) arranged on the other shaft (2) , the unit ,being characterized in that said device (8) has a symmetrical configuration with respect to said plane of symmetry and comprises: a pair of splicing cylinders (11, 12) , 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 (26, 27, 30) for driving the rotation and the displacement of said cylinders; groups of aligned suction holes (113) 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 cylinder (11) , i first cutting means (13) cooperating with a cylinder (11) , downstream of the area of contact with the other cylinder (12) , to transversely cut the material retained on the cylinder (11) along a generatrix thereof, and second cutting means (24) , arranged upstream, in turn for cutting said material transversely; and control means for /[controlling said drive means (26, 27, 30) in order to synchronize the movement of the cylinders with the speed at which said material is unwound from said rolls (Bl,

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 of the previous claims, wherein said second cutting means (24, 25) are mounted according to an adjustably movable arrangement.