The present invention relates to a winding or rewinding machine for forming rolls of web material. According to another aspect the invention relates to a method for winding a web material in rolls.
In numerous industrial fields, and in particular in the field of paper converting—especially converting of tissue paper for producing rolls of toilet paper, rolls of kitchen towels and the like—so called rewinding machines are used that, starting from one or more paper material reels of large diameter, form individual logs of axial dimension equal to the width of the web material, typically 2-5 m, and of diameter equal to the diameter of the rolls destined for the final consumption. The logs produced by the rewinding machine are subsequently cut into a plurality of rolls of the desired axial length.
In the modern rewinding machines, winding is carry out through a so called peripheral or surface system, wherein the log being formed is maintained in a winding cradle formed by a plurality of rollers rotating in a concordant direction and in surface contact with the log being formed so as to transmit the winding motion. In other older rewinding machines winding is carried out in a cradle, in which the log is maintained on a winding spindle, to which the rotation movement is imparted. There are also machines combining a peripheral winding system with spindles or tail chucks for supporting and controlling the log being formed.
In general, the rewinding machines have members for interrupting the web material, which is fed continuously by the reels present in the unwinders, at the end of winding of each individual log. These severing members are synchronized with the means or devices that start winding of the subsequent log.
In some rewinding machines winding is carried out around tubular winding cores mounted on winding spindles. The tubular cores are usually made of plastic, paper or cardboard, and they remain inside the log after winding. In other rewinding machines the winding spindle is extracted so as to obtain a log provided with a central hole, but devoid of winding cores. In further types of rewinding machines winding is carried out without a winding spindle, by simply winding the web material around itself, starting from a central nucleus and forming around this latter the finished log.
Independently of the type of used rewinding machine, the start of the winding of each individual log is one of the critical aspects during the winding phases. When winding is carried out around tubular cores, one of the critical aspects is represented by the transport of the leading end, formed by cutting or severing the web material, to the new core and by the start of the winding of the first turns. Different systems have been designed to perform the operations of severing the web material, transporting and anchoring the winding cores. U.S. Pat. No. 6,648,266 and U.S. Pat. No. 5,979,818 disclose a particularly efficient rewinding machine, wherein the web material is severed by means of a rotating member which pinches the web material against a movable surface, for example against the surface of the main winding roller of a winding cradle of the peripheral type. The winding core, is provided with a glue to anchor the leading edge generated by severing and to start in this way the winding of the subsequent log. The severing member acts on the web material in a position intermediate between the log which has been just wound and the new winding core inserted in the machine.
Rewinding machines produced according to this principle are extremely efficient and allow to achieve high winding speeds thanks to the efficient control on the free end of the web material after it has been severed. However, due to the way in which the web severing system is designed, the logs are formed around the winding cores with a head portion forming, inside each log, a fold of particularly great length. This entails irregularities in the first winding turns and a quality of the finished product not equal to that which can be obtained through other slower winding systems. Furthermore, as the severing member acts between the log, wound during the winding cycle which is ending, and the new core which is being inserted, it is necessary to have a particularly long rolling surface, and therefore a particularly long insertion channel.
Other rewinding machines having web material severing systems arranged upstream of the area of insertion of the winding cores are disclosed in EP1525148.
WO 2007/081244 discloses a perforating device that can be used in a rewinding machine, wherein on the toothed blades of the perforator a colored liquid is applied. This known device has the function of coloring the perforation lines that separate each of the various sheets of a roll in tissue paper by means of the liquid.
According to one aspect, an object of the present invention is to provide a rewinding machine that completely or partially overcomes at least one of the problems of the known rewinding machines. According to another aspect, a further object of the present invention is to provide a winding method using a rewinding machine, preferably of the peripheral type, wherein one or more of the problems of the traditional methods are completely or partially overcome.
Substantially, the invention is based upon the concept of interrupting, severing, or cutting, the web material in two phases. In a first phase the web material is weakened at a line, along which severing of the web material is subsequently completed, thus forming the tail end of the log, the winding of which is being completed, and the leading end destined to form the subsequent log.
According to one embodiment, the present invention provides a rewinding machine comprising: a web material feed path; a winding cradle, preferably of the peripheral type; severing members for interrupting the web material at the end of winding of each log; a weakening device for weakening the web material along a substantially transverse severing or weakening line, in correspondence of which the web material is severed at the end of winding of a log. The weakening device is controlled so as to generate the weakening line synchronized with the completion of winding of the log.
In some embodiments the rewinding machine according to the present invention provides an inserter for winding cores or spindles, to produce log of web material wound about tubular winding cores or spindles. Preferably, but not necessary, the tubular cores are destined to remain inside the log. In some cases, they are provided with a glue, applied for example along one or two rows having a continuous or discontinuous development in the substantially longitudinal direction of the tubular core, for the purposes that will be described in greater detail hereunder.
By means of a rewinding machine of this type it is possible to weaken the web material in an adequate position along the path of the web material upstream of the area in which it will be definitely severed to form the leading and tail ends during the exchange phase, i.e. during the phase in which the finished log is separated from the web material and unloaded from the machine and the new log starts winding.
Through a weakening line of this type it is possible to maintain the control on the web material fed along the feed path across the machine, from the position in which the weakening member or device is arranged and the position, preferably downstream (according to the direction of feed of the web material) of the area of insertion of the winding core, without the need for using vacuum members or other complex retaining systems for retaining the leading end of the web material. Moreover, the weakening of the web material upstream of the area of insertion of the winding core allows to obtain the subsequent complete severing of the web material with a particularly simple system, for example with a very limited acceleration of one of the winding rollers forming the winding cradle. This can be obtained thanks to the fact that the web material has been previously weakened along the weakening line during the first phase of the operations for severing the material.
In some embodiments, when a winding core is used, provided with a glue to transfer on the core itself the free leading end of the web material, severing of the web material can be completed simply due to the effect of the adhesion between the web material and the core by means of the glue applied on the core. In this case the severing members for interrupting the web material are represented by the same core inserter which is synchronized with the position of the weakening line generated on the web material.
According to a different aspect the invention relates to a method for winding logs of web material about winding cores, wherein: at the end of winding of a log, in a weakening position arranged along the feed path of the web material upstream of the severing position, a weakening line is formed on the web material; the web material is fed along the feed path, bringing said weakening line towards the severing position, and is severed in said severing position.
In some embodiments it is provided for the web material to be weakened by applying a liquid, preferably a water based liquid, in correspondence of said weakening line.
Further advantageous features and embodiments of the rewinding machine and of the method according to the present invention are indicated in the appended claims and shall be described hereunder with reference to the attached drawings.
The invention will be better understood by following the description below and the attached drawing, which shows a non-limiting practical embodiment of the present invention. More particularly, in the drawing:
With initial reference to
In some embodiments the rewinding machine 1 has a perforating unit 11 (
The path of the web material N develops through the perforating unit 11 (if present) and around a guide roller 13 arranged nearly close to the winding roller 3, around which the path of the web material N continues to develop until it achieves and crosses the nip 9 between the winding rollers 3 and 5 and then enters into the winding cradle in order to wind around the winding core A and form the log R.
The above described structure is a typical structure of a so called surface or peripheral rewinding machine, wherein the log R is formed by maintaining it in rotation by contact between the rollers 3, 5, and 7. Also different conformations can be provided for the winding cradle and/or the presence of tail chucks for supporting and controlling the winding cores in at least some of the phases of formation of a log, as it is well known to those skilled in the art.
According to some embodiments, around the winding roller 3 a rolling surface 15 develops, defining a channel 17 between the surface 15 and the cylindrical surface of the winding roller 3. The winding cores A are sequentially inserted, in the manner described below, inside the channel 17 so as to start the cycle of winding of each log.
The rewinding machine 1 comprises a weakening device 21 arranged, designed and controlled so as to weaken the web material N in correspondence of a weakening line, along which the web material N will be subsequently severed to form the tail end of the log R and the head end from which the winding of the subsequent log will start.
In some embodiments, the weakening device 21 comprises an element 23 that rotates in a controlled manner around an axis of rotation 23A substantially parallel to the axis of rotation of the rollers 3, 5, 7, and 13.
In some embodiments, as shown in the drawing, the weakening device 21 is designed so as to apply a liquid, preferably for example a water-based liquid, on the web material N along a substantially transverse line. In some embodiments the liquid can be simply water, although other embodiments would be possible, for example the application of a colored liquid when one desires for example optically to mark the position of the severing line of the web material. In other embodiments the liquid applied by the weakening device 21 can be constituted by or can contain an adhesive or glue, so that following the complete severing of the web material the free tail end can automatically adhere to the formed log R and/or the head end can automatically adhere to the new winding core without the need for further glue.
In the illustrated embodiment the dispensing member comprises at least one rotating element 23, which at its distal end is provided with a pad 25 which is wet with water or other suitable liquid to be applied to the web material N. In order to wet the pad 25 it is possible for example to provide the rotating element 23 with a movement of immersion inside a tank 27 containing the liquid, which is generically indicated with L. In this way the rotating element 23 can immerse the pad 25 inside the tank 27 in order to wet it. The extraction movement for extracting the pad 25 from the tank 27 allows the subsequent application of the liquid on the web material as described in greater detail hereunder.
In other embodiments, as illustrated in the drawing, the pad 25 is wet with the liquid L by a movable member 20 which is completely or partially housed inside the tank 27 and provided with an alternate immersion and emersion motion according to the double arrow f29. In this way it is possible to maintain the rotating element 23 with its pad 25 completely outside the tank 27, avoiding the movement of the element 23 for immersing the pad 25 in the liquid L contained inside the tank. In this case the member 29 transfers the liquid from the inside of the tank 27 to the pad 25 every time it is necessary, for example for each winding cycle, i.e. each time that an individual log R is wound. Alternatively, guns or nozzles in series can be provided, instead of the member 29, for wetting the pad 25.
In the illustrated embodiment the logs R are wound around substantially circular winding cores A, for example cores made of cardboard, plastic, paper or the like. According to the illustrated embodiment, a glue is applied on the winding cores A. The glue is preferably applied according to two nearly longitudinal lines, i.e. substantially parallel to the axis of the winding cores A or, anyway, extending along the length or at least a great part of the length of the winding cores A. The lines of glue can be continuous or discontinuous, can be formed by individual areas of different shape, provided that they are arranged with a frequency and a distance from each other sufficient to guarantee the anchoring of the free leading end formed by the web material N following the severing thereof, as described hereunder.
In the embodiment illustrated in
It is also possible to use movable members for lifting the glue from the individual tanks 31A, 33A with different shapes but having substantially the same function as the members 31B, 33B. For example, a thread can be provided, movable along a closed path defined for example between two pulleys. The upper segment of the thread is arranged at an area of application of the glue to the cores A, corresponding to the position taken by the movable members 31B, 33B when they are lifted, and a lower segment immersed in the glue C1, C2, for example in a position corresponding to that taken by the members 31B, 33B when they are immersed in the glue.
To the glue dispenser 31 a first transferring unit 35 is associated, which picks up individual cores A from a storage device 37 and transfers them individually, after they have individually received a first line of glue, to a second transferring unit 39 associated to the second glue dispensing member 33. The transferring member 39 then transfers the cores towards the entrance of the channel 17, into which the cores are inserted to start the cycle of winding each individual log R according to the method described below.
In
In
The web material, wet along the weakening line with the liquid L, continues to adhere to the winding roller 3, even if greatly weakened, due to the liquid impregnating the cellulosic fibers of which the web material N (typically tissue paper) is made. In this way control of the web material N is maintained, which is not completely severed following the weakening caused by the liquid applied by the pad 25. The control of the web material is further improved thanks to the fact that the liquid L, which has impregnated the web material N along the weakening line, tends to make the web material to adhere to the winding roller 3. This latter can be coated, partially or completely, for example along annular areas, with a material with a high friction coefficient, so called “grip” material, which assures a further control on the web material N and the transferring thereof along the feed path around the winding roller 3.
In
In the phase illustrated in
In fact, along this weakening line the web material, soaked with liquid, has a very low tensile strength and substantially looses its elasticity. The slight traction, to which the web material N is subjected due to the effect of the relative movement between the core A rolling on the surface 15 and the web material N tending to rotate with the roller 3, causes tearing, i.e. complete severing of the web material along the weakening line I. Tearing practically occurs thanks to the fact that the trajectory of the web material is altered by the presence of the winding core. When the web material adheres to the core, and this latter rolls in the introduction channel, the web material is forced to leave its original trajectory (along the surface of the winding roller 3) and starts to follow the surface of the winding core.
What is obtained is represented in
For a better understanding of the mechanism for weakening and subsequently severing the web material,
More in particular,
In view of what has, been described and illustrated above, it should be understood that with the rewinding machine according to the present invention the operation of severing the web material is substantially subdivided into two phases: in a first phase the weakening is performed along the line I of the web material by means of the device 21. In a second phase the interruption is accomplished, i.e. it is completed forming the leading and tail ends LT, LC, exerting a very modest mechanical action sufficient to overcome the remaining resistance of the cellulosic fibers of the web material N in correspondence of the weakening line I. As indicated above, this interruption is also obtained simply due to the effect of the traction exerted on the web material N by the glue, which makes the head end LT to adhere on the new core A inserted in the machine. In this way it is not necessary to have expensive additional members for cutting or severing the web material. The whole rolling channel 17 remains devoid of mechanical members and the portion of web material between the leading end LT and the adhesion or anchoring point in correspondence of the line of glue RC1 is extremely short, thus obtaining a very regular winding without creases also of the first part of web material N of each log R.
In this embodiment the weakening device 21 comprises again a rotating element 23, which, however, does not receive the liquid L from a tank, but projects it through a nozzle carried at the distal end of the rotating element 23, so as to form an adequately shaped jet G of liquid, or a plurality of jets arranged side by side. These jets wet the web material N, thus forming the weakening line I. In order to obtain an easier synchronization and to avoid that the weakening line I is produced with an excessive dimension in the direction of the longitudinal development of the web material, to the rotating element 23 screens 24A, 24B can be associated, between which a slot is defined, developing nearly parallel to the axis of the winding roller 3. In this way the jet or jets G of liquid L generated by the nozzles carried by the rotating element 23 wet an area I of very limited dimensions.
Even if the weakening obtained through the application of a liquids is particularly advantageous as, among other things, it allows to maintain a better control of the web material that thanks to the liquid tends to adhere to the roller 3 in a manner sufficient not to detach due to the effect of the ventilation caused by the rotation of the roller 3, in other embodiments the weakening line can be generated mechanically or pneumatically. At this end nozzles can be provided inside the winding roller 3, which generate air flows in an angularly preset position in correspondence of the weakening line I. Alternatively, the air flows can be generated by an external system, similar to that represented by the element 23 in
In a different embodiment, shown in
Both in the configuration of
The glue C1 for anchoring the leading end of the web material on the new core A is usually a more sticky glue, i.e. a glue harder than the glue C2, with which the tail end LC is anchored to the log R in order to seal it. In other embodiments the tail end LC can be closed by the adhesion effect given by the same liquid L applied by the weakening device 21, for example providing that the liquid L is a water solution also with high dispersion of an adhesive or glue. The quantity of glue in the liquid L and the quantity of liquid L applied to the web material N will be determined in such a manner as to avoid dirtying of the winding roller 3.
The use of a glue on the winding core, in order to make the leading end of the web material N adhere on the winding core following severing, is particularly advantageous as in this way there is no need for additional members for cutting or severing or tearing the web material: the weakening along the line I is sufficient to cause tearing of the web material due to the retention effect of the glue C1 on the core A.
Moreover, the concept upon which the invention is based can be implemented, although with lesser advantages, also in machines wherein a glue is not used, or wherein the glue is not sufficient to obtain tearing or complete interruption of the web material following the weakening thereof. For example, the web material can start the winding around the tubular core A due to the effect of electrostatic adhesion, through air flows or in any other manner, avoiding the application of glue on the winding cores. This is particularly useful when the winding cores are subsequently extracted from the log, which in this case will be a coreless log. In these cases, and also when the used glue has not sufficient adhesive power to cause the tearing of the web material weakened along the weakening line I, severing of the web material can be obtained in other manner.
In some embodiments interruption can be obtained for example by temporarily accelerating the upper winding roller 7, so as to cause a tension in the web material. This tearing system is already used in prior art machines. It however has the disadvantage that the high resistance and elasticity of the paper requires great accelerations of the movable winding roller. In fact, it is necessary to tension the paper or other web material N, with very modest accelerations, beyond the breakage limit thereof in order to obtain tearing along the weakening line, for example along a perforation line. In absence of other measures, also due to the elasticity that these materials (typically tissue paper) present, it is necessary to use very powerful and over dimensioned motors, able to accelerate in a very sudden manner to control the rotation movement of the winding roller 7.
By using the concept upon which the present invention is based, the previous weakening of the web material along a weakening line, along which the severing will be subsequently performed, allows on one hand to maintain the control of the web material N until the weakening line I is brought downstream (relative to the direction of feed of the material N) relative to the new winding core, and at the same time to obtain the tearing or severing of the material with much more modest accelerations of the winding roller 7, independently of the presence of the line of glue on the core. Furthermore, a high accurateness is not necessary in the position of the weakening line relative to the moment in which the roller 7 is accelerated.
In other embodiments, severing can be for example obtained by means of air flows generated by nozzles arranged in annular grooves of the winding roller 3 or housed inside this latter, which, in this case, can be provided with a series of perforations, through which the pressurized air flows pass, which cause tearing of the web material. In this case again the weakening made by the device 21 eases and facilitates tearing, which can occur with much more modest air pressures and therefore with advantages in terms of energy and of reduction of noise during operation of the machine.
In some embodiments, the winding roller 3, around which the web material N is driven and with which the web material remains into contact after it has been wet, can be processed so as to avoid that the web material N (generally constituted by tissue paper with one or more plies) remains adhering to the roller due to the effect of moistening.
In other embodiments a system can be provided for facilitating the detachment of the web material N from the roller 3 and/or facilitating the start of the winding of the web material N around the winding core A.
In this embodiment the roller 3 has a cylindrical shell perforated with holes 3F, preferably distributed along the whole circumferential development of the roller. Inside the roller 3 a casing 3C is provided, inside which pressurized air is inserted and from which the pressurized air exits towards the inner cylindrical surface 3S of the roller 3. In this way it is possible to generate an air flow through the holes 3F of the roller 3. The angular position of the casing 3C, and consequently the angular position f the air flow, can be changed or adjusted according to the requirements and the conditions of operation.
Downstream of the area where air is blown from the roller 3, and upstream of the nip 9 between the winding rollers 3 and 5, an oscillating member 6 is arranged, hinged around ax axis 61A of oscillation and carrying, at its end, a plurality of nozzles 63 for blowing air, aligned according to a cross direction, i.e. orthogonally to the plan of the figure.
The operation of this machine is clearly illustrated by the sequence of
When the core A passes in the area where the device 61 is arranged, and overtakes it, this latter is made to oscillate in clockwise direction so as to generate an air flow through the nozzles 63, which facilitates the winding of the first turn of web material, in addition to the mechanical effect due to the rotation of the device 61 (
In some embodiments the device 61 can be omitted. In other embodiments, it can be replaced for example with a system of fixed nozzles, for example arranged with different angulations, and actuated sequentially so as to direct towards the initial free end LI an air flow oriented so as to facilitate the winding of the first turn of web material.
In some embodiments the system for blowing air from the inside toward the outside of the roller 3 can be combined with a system for applying double glue, as provided in the embodiments previously described, to apply glue both to the final end and to the initial end of the web.
It is also possible to omit the gluing of the core A completely, and to glue the final tail end LC outside of the rewinding machine with a sealer of the traditional type, whilst the adhesion of the initial free end LI on the core A is assured by the liquid applied along the weakening line I.
It is understood that the drawing only shows an example provided by way of a practical arrangement of the present invention, which can vary in forms and arrangements without however departing from the scope of the concept underlying the invention. Any reference numbers in the appended claims are provided for the sole purpose of facilitating reading of the claims in the light of the description and the drawing, and do not in any manner limit the scope of protection represented by the claims.
Number | Date | Country | Kind |
---|---|---|---|
FI2008A000181 | Sep 2008 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/IT2009/000423 | 9/18/2009 | WO | 00 | 2/14/2011 |