REWINDING MACHINE AND A WINDING METHOD FOR A WEB OF ABSORBENT SUBSTRATE

Abstract

A rewinding machine arranged to wind a web of absorbent substrate into multiple logs including a perforating module, a cutting module, a winding module and a control module, the web of absorbent substrate travelling into the modules according to a machine direction, wherein the perforating module is arranged to provide the web of absorbent substrate with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction, wherein the cutting module is arranged to sever the web of absorbent substrate substantially transversally relatively to the machine direction, wherein the winding module is arranged to wind the web of absorbent substrate so as to produce logs of web of absorbent substrate, and wherein the control module is coupled to the perforating module and to the cutting module and controls the modules operations.

Description

FIELD OF THE INVENTION

An aspect of the invention relates to a rewinding machine for a web of absorbent substrate. Another aspect of the invention relates to a winding method for a web of absorbent substrate. Such an absorbent substrate may be converted into absorbent sheet products that have a particular, though non-exclusive, use as sanitary or domestic purposes. As an example, such absorbent sheet products in roll may be used as toilet paper in restrooms. Others uses as napkins, towels, bath tissues, wipes, kitchen towels etc. . . . are possible. These products are manufactured for Away From Home use or Consumer Tissue home use.

BACKGROUND OF THE INVENTION

The web of absorbent substrate may be a web of tissue paper that is obtained by a Conventional Wet Press or Through Air Drying manufacturing method or other manufacturing method. A tissue paper relates to an absorbent paper based on cellulose fibers which is also called tissue paper base sheet in this field of technology. A typical absorbent paper has a low basis weight, in the range from 10 to 60 g/m², preferably 30 to 50 g/m².

The web of absorbent substrate may also be a web of nonwoven fabric that is obtained by an air-laid manufacturing method or spun-laid manufacturing method or other manufacturing method. A nonwoven fabric comprising cellulosic fibers relates to an absorbent paper which is also called nonwoven or web made of fibers like air-laid web in this field of technology. A typical absorbent paper has a basis weight, in the range from 20 to 300 g/m², preferably 40 to 60 g/m².

A web of absorbent substrate is submitted to various converting steps before being wound as a log. One converting step comprises providing the web with regularly spaced transverse perforation/weakening lines. These perforation/weakening lines enables the end user to cut absorbent sheets of appropriate length from, for example, a roll.

The document WO 2010/035301 describes a rewinding machine and winding method. The rewinding machine comprises a weakening device for weakening the web material along a substantially transverse weakening line, along which the web material is severed at the end of the winding of a log. The weakening device is controlled so as to generate the weakening line in a manner synchronized with the completion of winding of said log.

However, at the transition phase between two consecutive logs (more precisely when the finished log is separated from the web and a new log starts to be wound), due to the manufacturing of logs at an industrial manufacturing speed (up to 1.000 m/min), constraints are generated that may result in the web breaking-up in a zigzag fashion at the severing line, i.e. in the machine direction. This effect may even result in the creation of longitudinal line of weakness. As a consequence, it may further generate the propagation of a web break-up close to the zone where the separation occurs.

Thus, there is a need to improve the separation between consecutive logs in the converting machine. Further, this should be obtained in an economical or a cost-effective manner.

SUMMARY OF THE INVENTION

It is an object of the invention to propose a rewinding machine that overcomes the drawbacks of the prior art rewinding machine. In particular, it is desirable to avoid, or at least to reduce, the formation of a zigzag selvage at the interruption of the web between two consecutive logs. More particularly, the invention seeks to solve this issue even for web of absorbent substrate running at an industrial manufacturing speed in a converting machine (e.g. up to 1.000 m/min).

According to one aspect, there is provided a rewinding machine arranged to wind a web of absorbent substrate into multiple logs comprising a perforating module, a cutting module, a winding module and a control module, the web of absorbent substrate travelling into said modules according to a machine direction,

wherein the perforating module is arranged to provide the web of absorbent substrate with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction,

wherein the cutting module is arranged to sever the web of absorbent substrate substantially transversally relatively to the machine direction,

wherein the winding module is arranged to wind the web of absorbent substrate so as to produce logs of web of absorbent substrate, and

wherein the control module is coupled to the perforating module and to the cutting module and controls said modules operations such that:

• • at a transition phase between two consecutive logs, the control module deactivate the perforating module and activate the cutting module, and
  • out of transition phases, the control module activate the perforating module and deactivate the cutting module.

At the transition phase between two consecutive logs, the control module may be arranged to deactivate the perforating module and activate the cutting module from a first time corresponding to a log production cycle completed between 99.8% and 95% to a second time corresponding to a subsequent log production cycle completed between 0.2% and 5%.

Out of transition phases, the control module may be arranged to activate the perforating module and deactivate the cutting module from a first time corresponding to a log production cycle completed between 0.2% and 5% to a second time corresponding to the log production cycle completed between 99.8% and 95%.

According to another aspect, there is provided a use of said rewinding machine for manufacturing logs of absorbent sheet products chosen among the group comprising napkins, towels, kitchen towels, hand towels, toilet papers, wipes and facial tissues.

According to a further aspect, there is provided a winding method, the winding method comprising the steps of:

• • conveying the web of absorbent substrate according to a machine direction,
  • perforating the web of absorbent substrate by providing the web of absorbent substrate with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction,
  • winding the web of absorbent substrate so as to produce logs of web of absorbent substrate,
  • severing the web of absorbent substrate substantially transversally relatively to the machine direction at a transition phase between two consecutive logs,
  • controlling the perforating step and the severing step such that:
    • at a transition phase between two consecutive logs, stopping the perforating step and resuming the severing step, and
    • out of transition phases, resuming the perforating step and stopping the severing step.

At the transition phase between two consecutive logs, the perforating step may be stopped and the severing step may be resumed from a first time corresponding to a log production cycle completed between 99.8% and 95% to a second time corresponding to a subsequent log production cycle completed between 0.2% and 5%.

Out of transition phases, the perforating step may be resumed and the severing step may be stopped from a first time corresponding to a log production cycle completed between 0.2% and 5% to a second time corresponding to the log production cycle completed between 99.8% and 95%.

According to still a further aspect, there is provided a log of absorbent sheet products produced according to said winding method.

With the invention, it is possible to avoid, at least greatly reduce, the constraints generated that may result in the web breaking-up in a zigzag fashion when the web is severed at the transition phase between two consecutive logs.

Other advantages will become apparent from the hereinafter description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of examples and not limited to the accompanying drawings, in which like references indicate similar elements:

FIG. 1 is a partial side cross-section view schematically illustrating a converting machine/line comprising an exemplary embodiment of a rewinding machine arranged to wind a web of absorbent substrate into multiple logs; and

FIGS. 2 and 3 are partial perspective views schematically illustrating the position of perforation lines with respect to cutting line into a web of absorbent substrate at the transition between two logs, for two different types of perforation lines.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a partial side cross-section view schematically illustrating a converting machine/line 1 comprising an exemplary embodiment of a rewinding machine 5 arranged to wind a web of absorbent substrate 11 into multiple logs 30. In this example, the converting machine/line 1 comprises two unwinding units 2 and 3, an embossing unit 4, and the rewinding machine 5.

More precisely, at the stage of FIG. 1, absorbent log base webs 10A, 10B have already been produced according to a known papermaking process. FIG. 1 illustrates a later stage which is a stage where a converting process takes place. The converting process converts large parent log base webs 10A, 10B (e.g. having a strip width from around 1.80 m to around 7 m) into retail sized rolls 40, e.g. bathroom tissue rolls, paper towels rolls (e.g. having a strip width from around 8 cm to around 40 cm). In this example, the converting machine/line 1 produces retail sized rolls having two plies.

A first unwinding unit 2 provides a first absorbent log base web 10A from a first parent roll 7. A second unwinding unit 3 provides a second absorbent log base web 10B from a second parent roll 8. Both absorbent log base webs 10A, 10B are fed to the embossing unit 4.

Various rollers 9 are appropriately positioned in order to control the path of the absorbent log base webs 10A, 10B along the converting machine/line 1, within and between the various units 2, 3, 4, 5. The absorbent log base webs 10A, 10B travels into the converting machine/line 1 according to the machine direction MD from the unwinding units 2 and 3, towards the embossing unit 4, and towards the rewinding machine 5.

The embossing unit 4 comprises an engraved cylinder 12, a mating rubber cylinder 13, both rotating in opposite directions, and a glue dispenser 14. The absorbent log base webs 10A, 10B are superposed and combined into the embossing unit 4 in order to form a web of absorbent substrate 11. The engraved cylinder 12 may be engraved with a microstructure pattern combining various embossing tips (not shown). The engraved cylinder 12 may perform a simple or a double-level engraving into the superposed absorbent log base webs 10A, 10B. The glue dispenser 14 typically comprises a vat, an applicator cylinder and a dipping cylinder. The applicator cylinder abuts the superposed absorbent log base webs 10A, 10B against the engraved cylinder 12. The dipping cylinder picks up the adhesive in the vat and transfers the adhesive to the applicator cylinder. The applicator cylinder is arranged to exercise a determined pressure on the engraved cylinder at the distal area of protuberances of the embossed absorbent log base webs 10A, 10B. At said determined pressure, the adhesive crosses through both absorbent log base webs 10A, 10B. This is used to combine both webs and, also, to emboss or micro-emboss at least one of the absorbent log base webs 10A, 10B in order to generate esthetical effects or modify the thickness, or the softness, or the suppleness of the resulting web of absorbent substrate 11. Such steps are known in the art, not germane to the current invention, and, therefore, will not be described in details.

The rewinding machine 5 comprises a perforating module 20, a cutting module 21, a winding module 22 and a control module 50. The rewinding machine 5 winds the web of absorbent substrate 11 into multiple logs 30.

The perforating module 20 is arranged to provide the web of absorbent substrate 11 with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction MD (i.e. the perforation lines are substantially orientated according to the cross-machine direction CD).

The cutting module 21 is arranged to sever the web of absorbent substrate 11 substantially transversally relatively to the machine direction (i.e. the separation line is substantially orientated according to the cross-machine direction CD). The severing of web occurs at a transition phase, namely when a first log is finished at the end of a log production cycle, and before a second subsequent log starts to be wound at the beginning of a new log production cycle.

The winding module 22 is arranged to wind the web of absorbent substrate 11 so as to produce logs 30 of web of absorbent substrate. For example, the winding module 22 is of the peripheral or the surface type. The winding module 22 comprises a rolling surface 23, a first winding roller 24, a second winding roller 25, a third winding roller 26 and a core supplier 27. The log 30 is formed by winding the web of absorbent substrate 11 onto a core 41. Cores 41 are sequentially provided by the core supplier 27 through the rolling surface 23 before the beginning of a new log production cycle. The log 30 is maintained in position during the winding by the first, second and third winding rollers 24, 25, 26 rotating in surface contact with the log 30. One of the winding rollers 24, 25, 26 imposes the rotation movement of the log 30.

The control module 50 is coupled to the perforating module 20 and to the cutting module 21 by means of an interface 51. The control module 50 controls the operation of the perforating module 20 and the cutting module 21 in an independent manner. The control module 50 deactivates the perforating module 20 and activates the cutting module 21 at a transition phase between two consecutive logs. The control module 50 activates the perforating module and deactivates the cutting module 21 out of transition phases.

At the transition phase between two consecutive logs 30, the control module 50 deactivates the perforating module 20 and activates the cutting module 21 from a first time corresponding to a log production cycle completed at around 99.8% to a second time corresponding to a subsequent log production cycle completed at around 0.2%.

Out of a transition phase, the control module 50 activates the perforating module 20 and deactivates the cutting module 21 from a first time corresponding to a log production cycle completed at around 0.2% to a second time corresponding to the same log production cycle completed at around 99.8%.

Thus, the perforating module 20 operates during almost around 99.6% of the log production cycle, while the cutting module 21 operates during only around 0.4% of the log production cycle.

The hereinbefore mentioned values related to the completed log production cycle and operating range are examples, said cycle can be extended from 0.2% to 5% and from 99.8% to 95%, thus said operating range can be modified from 99.6% to 90% and from 0.4% to 10%. Playing on the duration of the transition phase enables controlling the length of the first sheet in the produced log (and therefore also in the produced individual roll). A long first sheet enables protecting the log and also the individual roll before use, like a wrap.

The produced log 30 is then cut by multiple log saws 31 into multiple and individual rolls 40 of absorbent material sheet.

FIGS. 2 and 3 are partial perspective views schematically illustrating the position of perforation lines 28 or 38 with respect to a cutting line 29 into a web of absorbent substrate 11 at the transition Δt between two logs 30, for two different types of perforation lines.

The web of absorbent substrate 11 is fed into a space of the perforating module 20 comprising a perforator roll and a stationary anvil roll. There, the web of absorbent substrate 11 is pinched (step S1) with the desired perforation or tear lines 28, 38 (schematically represented by dashed lines).

A perforation line 28 according to the first type of perforation (see FIG. 2) is a line according to a cross-machine direction CD made in the thickness of the web of absorbent substrate 11 and comprising alternating perforated segments and unperforated segments (i.e. two perforated segments being separated by one unperforated segment or vice-versa). Each unperforated segment forms an attachment area between two consecutive portions (according to the machine direction MD) of the web of absorbent substrate 11. Each perforated segment forms a detachment area between two consecutive portions (according to the machine direction MD) of the web of absorbent substrate 11. Considering the width of the individual roll, for example between 10 cm and 30 cm, each said unperforated/perforated segment ranges, for example, between 4 mm and 10 mm.

Two consecutive perforation lines 28, 38 define the individual sheet length in the individual rolls 40 of absorbent material sheet. For example, a sheet of a bathroom tissue rolls may have a length of around a few dozen of centimeters. In FIGS. 2 and 3, multiple phantom lines 32 parallel to the machine direction MD are also represented on the web of absorbent substrate 11 for the sole purpose of illustration. The phantom lines 32 are spaced apart in the cross-machine direction CD. They schematically represent imaginary lines where the web of absorbent substrate 11 will be cut into multiple and individual rolls 40. Thus, two adjacent phantom lines define the future edges of an individual roll. The distance between two consecutive phantom lines is equal to the full width of the individual rolls 40.

After the pinching step (step S1), the web of absorbent substrate 11 is wound (step S2) onto the core 41 in order to form a log 30 by means of the winding module 22.

Once the desired log diameter (corresponding to a substantially defined number of individual sheets wound in the log) is reached, the web of absorbent substrate 11 is cut or severed. The produced log 30 is separated (step S3) from the web of absorbent substrate 11 and subsequently a new log begins to be produced. The web of absorbent substrate 11 is fed into a space of the cutting module 21 comprising a cutting roll and a stationary anvil roll. There, the web of absorbent substrate 11 is severed by a cutting line 29 (schematically represented by two parallel continuous lines). At the transition phase Δt between two consecutive logs 30, the perforating module 20 is deactivated and the cutting module 21 is activated from a first time tL_n corresponding to a log production cycle completed at around 99.8% to a second time tL_n+1 corresponding to a subsequent log production cycle completed at around 0.2%.

A loose end forming a tail of the web of absorbent substrate 11 of the produced log 30 is adhered to the log in a known manner (step S4).

The produced log 30 is then cut (step S5) parallel to the machine direction MD by multiple log saws 31 into multiple individual rolls 40. The corresponding cuts in the produced log 30 are also represented by the multiple phantom lines 32 on the surface of the produced log 30.

A perforation line 38 according to the second type of perforation (see FIG. 3) differs from the first type of perforation in that the web of absorbent substrate 11 is pinched (step S1) with staggered perforation lines 38. One central region out of two in each perforation line is replaced by an unperforated region, and two consecutive perforation lines are staggered or offset according to a cross-machine direction CD such that all the central region are positioned between two adjacent phantom lines 32. In other words, each perforation line 38 comprises alternating perforated segments having a particular perforating pattern and long unperforated segments. The perforated segments are positioned in the middle of the full width defined by two adjacent phantom lines 32, more precisely at a distance, e.g. 4 mm from both phantom lines 32 that defines the future edges of the individual roll 40. The long unperforated segments form attachment areas within the tear line 38 according to the cross-machine direction CD of the web of absorbent substrate 11. Further, the long unperforated segments also form a plurality of attachment areas between two consecutive portions according to the machine direction MD of the web of absorbent substrate 11. Thus, such a perforation line 38 enables manufacturing individual roll 40 wherein individual sheets are easy to tear out. At the same time, during production of the log, the tensile strength of the perforation lines 38 is important such that blowouts in the web of absorbent substrate 11 is avoided, at least considerably reduced. Indeed, the breaks in the web of absorbent substrate 11 cannot propagate, at least with difficulty, along the perforation line 38.

The drawings and their descriptions hereinbefore illustrate rather than limit the invention.

Though the invention has been described with respect to two examples of perforations, these are not limitative examples. The skilled person will readily recognize that other kinds of perforation are possible.

Further, the described winding module of the peripheral or the surface type is only an example. The invention is also applicable to other kind of winding module, for example winding module using a spindle. Furthermore, the invention is not limited to log being formed around a core, in cardboard or plastic. The log may be coreless at the winding step, or the core can be temporarily present during winding and extracted at the end of the production process.

Furthermore, though the drawings show a particular horizontal positioning of the different modules/units/machines relatively to each other in the converting line, this is a mere example because the modules/units/machines can be positioned vertically or a combination of horizontal/vertical position. The relative position of the perforating module and the cutting module can be inversed. The converting line may also comprise additional modules/units/machines for performing specific converting steps not described herein. Also, the conversion of two plies is only an example as the invention would be applicable to end products comprising one ply or more than two plies.

The application of the absorbent product is broad in the domain of sanitary or domestic applications, e.g. napkins, towels, kitchen towels, hand towels, toilet papers, wipes, facial tissues, bath tissues etc. . . . .

Any reference sign in a claim should not be construed as limiting the claim. The word “comprising” does not exclude the presence of other elements than those listed in a claim. The word “a” or “an” or “at least one” preceding an element does not exclude the presence of a plurality of such element.

Claims

1. A rewinding machine arranged to wind a web of absorbent substrate into multiple logs comprising a perforating module, a cutting module, a winding module and a control module, the web of absorbent substrate travelling into said modules according to a machine direction,

wherein the perforating module is arranged to provide the web of absorbent substrate with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction,

wherein the cutting module is arranged to sever the web of absorbent substrate substantially transversally relatively to the machine direction,

wherein the winding module is arranged to wind the web of absorbent substrate so as to produce logs of web of absorbent substrate, and

wherein the control module is coupled to the perforating module and to the cutting module and controls said modules operations such that:

at the transition phase between two consecutive logs, the control module is arranged to deactivate the perforating module and activate the cutting module from a first time corresponding to a log production cycle completed between 99.8% and 95% to a second time corresponding to a subsequent log production cycle completed between 0.2% and 5%, and

out of transition phases, the control module activate the perforating module and deactivate the cutting module.

2. (canceled)

3. The rewinding machine according to claim 1, wherein, out of transition phases, the control module is arranged to activate the perforating module and deactivate the cutting module from a first time corresponding to a log production cycle completed between 0.2% and 5% to a second time corresponding to the log production cycle completed between 99.8% and 95%.

4. A method of manufacturing logs of absorbent sheet products chosen among the group comprising napkins, towels, kitchen towels, hand towels, toilet papers, wipes and facial tissues with the rewinding machine according to claim 1.

5. A winding method, the winding method comprising the steps of:

conveying the web of absorbent substrate according to a machine direction,

perforating the web of absorbent substrate by providing the web of absorbent substrate with regularly spaced perforation lines substantially transversally orientated relatively to the machine direction,

winding the web of absorbent substrate so as to produce logs of web of absorbent substrate,

severing the web of absorbent substrate substantially transversally relatively to the machine direction at a transition phase between two consecutive logs,

controlling the perforating step and the severing step such that:

at a transition phase between two consecutive logs, stopping the perforating step and resuming the severing step, and

out of transition phases, resuming the perforating step and stopping the severing step.

6. (canceled)

7. The winding method according to claim 5, wherein, out of transition phases, the perforating step is resumed and the severing step is stopped from a first time corresponding to a log production cycle completed between 0.2% and 5% to a second time corresponding to the log production cycle completed between 99.8% and 95%.

8. A log of absorbent sheet products produced according to the winding method according to claim 5.