Device for processing a continuous web material, in particular a cellulose web material

Abstract

The device comprises at least a first advancement path for a first ply of continuous cellulose web material. Along this path, a first endless flexible member is arranged. A second endless flexible member is provided along the same path. The endless flexible members extend along a first closed path and a second closed path, respectively, which have a common portion, along which the first endless flexible member and the second endless flexible member advance with the outer surface of the first endless flexible member pressed against the outer surface of the second endless flexible member. The first advancement path extends along the common portion, between the outer surface of the first endless flexible member and the outer surface of the second endless flexible member. First pressure members press the first endless flexible member and the second endless flexible member against each other along the common portion.

Description

DEVICE FOR PROCESSING A CONTINUOUS WEB MATERIAL, IN PARTICULAR A CELLULOSE WEB MATERIALDESCRIPTIONTECHNICAL FIELD

[0001] The present invention relates to the field of the processing or converting web materials, in particular web materials consisting of one or more plies, in particular for example tissue paper.BACKGROUND ART

[0002] In the tissue paper sector, it is known to produce cellulose webs starting from a slurry of water and cellulose fibres, which is distributed on a forming wire and from which the water is gradually removed by means of various drainage and / or drying systems. The cellulose plies thus obtained are subjected to a plurality of converting processes to obtain a finished product, often in the form of a roll, sometimes in the form of folded and possibly interfolded sheets.

[0003] One of the operations carried out on this type of paper is calendering, which involves the passage of a single continuous ply, or of a multi-ply web material in a nip formed between two rollers pressed against each other. In some cases, two or more plies are bonded together, for example by applying a functional liquid, which may comprise a glue, or by mechanical ply bonding.

[0004] These operations subject the plies of web material to high stresses, which can cause damage to the fibres and / or the structure (texture) that can be imparted to the ply during the formation step, i.e., in continuous machines that produce the cellulose ply starting from the slurry of cellulose fibres in aqueous suspension.

[0005] It would therefore be appropriate to develop different devices and methods for carrying out calendering, bonding or other processes, adapted to alleviate or eliminate the problems of the methods and devices of the known art.SUMMARY

[0006] In embodiments disclosed herein, a device is provided for processing a continuous cellulose web material, which device comprises at least a first advancementpath for a first ply of continuous cellulose web material. Along this path is arranged a first endless flexible member with an inner surface inside a first closed path of the first endless flexible member and an outer surface outside the first closed path. The outer surface of the first endless flexible member is approximately smooth. Along the same path, a second endless flexible member is provided with an inner surface inside a second closed path of the second endless flexible member and an outer surface outside the second closed path. The outer surface of the second endless flexible member is approximately smooth. The first closed path and the second closed path have a common portion, along which the first endless flexible member and the second endless flexible member advance with the outer surface of the first endless flexible member pressed against the outer surface of the second endless flexible member. The first advancement path extends along the common portion, between the outer surface of the first endless flexible member and the outer surface of the second endless flexible member. First pressure members press the first endless flexible member and the second endless flexible member against each other along the common portion.

[0007] Further features and embodiments of the device disclosed herein are illustrated below with reference to the attached drawings, and are defined in the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention will be better understood by following the description and the attached drawings, which illustrate exemplary and non-limiting embodiments of the invention. More in particular, the drawings show:Fig. 1 shows a device for bonding plies in a first embodiment;Figs. 2 and 3 show sections according to II-II and KI-HI of Fig. 1;Fig. 4 shows a device for bonding plies in a second embodiment;Fig. 5 shows a device for bonding plies in a third embodiment;Fig. 6 shows a device for bonding plies in a fourth embodiment; and Fig. 7 shows a calendering device in an embodiment.DETAILED DESCRIPTION

[0009] Figs. 1, 2 and 3 show a first embodiment of a device 1 for bonding plies of cellulose material, for example plies of tissue paper.

[0010] In Fig. 1 the device 1 comprises a first advancement path Pl for a first ply VIof web material, for example a cellulose ply in tissue paper. At least one guide roller3 to guide the ply VI towards a bonding unit 5 is provided along the first path.

[0011] The bonding unit 5 comprises a first endless flexible member 7 having two opposite surfaces 7A and 7B. The first surface 7A is inside a first closed path of the first endless flexible member 7 and will therefore be referred to as inner surface 7A. The surface 7B is an outer surface outside the first closed path and will therefore be called outer surface 7B. The outer surface 7B is preferably smooth. In this context, “smooth” means a surface that has no roughness, protrusions or bumps that could leave an imprint due to permanent deformation on the ply VI. The first endless flexible member 7 is guided around a first guide roller 11 and a second guide roller 13. The inner surface of the first endless flexible member 7 can be toothed, to mesh with a toothing of the guide rollers 11, 13.

[0012] The device 5 further comprises a second endless flexible member 15, with an inner surface 15A inside a second closed path of the second endless flexible member 15 and an outer surface 15B outside the second closed path. The two surfaces 15 A, 15B will also be indicated as inner surface and outer surface, respectively. The second endless flexible member 15 is guided around a third guide roller 17 and a fourth guide roller 19. Similarly to the first endless flexible member 7, the outer surface 15B of the second endless flexible member may be smooth, in the sense defined above, and the inner surface 15A may be toothed to mesh with the guide rollers 17 and 19.

[0013] The first closed path and the second closed path formed by the first endless flexible member 7 and the second endless flexible member 15 have a common portion, which extends between the pairs of guide rollers 11, 17 and 13, 19. Along the common portion of the closed paths of the first endless flexible member 7 and the second endless flexible member 15, the first endless flexible member 7 and the second endless flexible member 15 advance with the outer surface 7B of the first endless flexible member 7 pressed against the outer surface 15B of the second endless flexible member 15. The first advancement path Pl of the first ply VI extends along the common portion of the two closed paths, between the outer surface 7B of the first endless flexible member 7 and the outer surface 15B of the second endless flexible member 15. In the common portion of the two closed paths, the outer surfaces 7B and 15B of the endless flexible members 7 and 15 are pressed against each other in the manner described in detail below.

[0014] The device 1 comprises a second advancement path P2 for a second ply V2 of web material, for example a cellulose ply in tissue paper. Along the second path P2 there is at least one guide roller 23 to guide the second ply V2 towards the common portion of the two closed paths, between the outer surfaces 7B and 15B of the endless flexible members 7, 15. Therefore, the plies VI and V2 are pressed against each other by the endless flexible members 7 and 15.

[0015] A functional fluid, for example a functional liquid, which may comprise glue or consist of glue, is applied to a surface of one of the plies VI, V2, oriented towards the other ply. In the embodiment illustrated in Fig. 1, a functional liquid applicator 101 is provided for this purpose along the first path Pl, which applicator 101 is configured to apply functional liquid onto the ply VI.

[0016] The applicator 101 may comprise a cliche roller or applicator roller 103, which receives the functional liquid from a reservoir 104. The applicator roller 103 cooperates with a counter-roller 105. A nip 107 is formed between the applicator roller 103 and the counter roller 105. The ply VI advances through the nip 107 and receives the functional liquid, for example glue, on the surface which, in the bonding nip between the plies VI, V2 (formed by the common portion of the two closed paths of the endless flexible members 7 and 15) is facing the ply V2.

[0017] The applicator roller 103 may be a patterned roller, i.e., it may have raised areas and cavities, such that the functional liquid is applied to the ply VI in a patterned manner, i.e., in areas, for example along longitudinal strips. While in Fig. 1 the applicator roller 103 draws the functional liquid directly from the source or reservoir 104, in other embodiments an intermediate roller, also called anilox roller or screen roller, may be provided which transfers the functional liquid from a reservoir to the applicator roller.

[0018] The endless flexible members 7, 15 are pressed against each other by an arrangement of pressure plates, anvil plates and actuators, described in more detail below with reference to Figs. 1, 2 and 3.

[0019] In the illustrated embodiment, the pressure members for pressing the endless flexible members 7 and 15 together comprise a pressure plate 51, located inside one of the closed paths formed by the endless flexible members 7 and 15. In the illustratedembodiment, the pressure plate 51 is located inside the closed path formed by the first endless flexible member 7. An anvil plate 53 is located inside the other of said first closed path and second closed path, in the illustrated example inside the closed path formed by the second endless flexible member 15.

[0020] The pressure plate 51 and the anvil plate 53 are positioned opposite each other along the common portion of the first closed path and the second closed path. Furthermore, actuators configured to push the pressure plate 51 against the anvil plate 53 are provided.

[0021] In the embodiment illustrated in Figs. 1, 2 and 3, the actuators comprise first actuators 55 and second actuators 57, offset along the common portion of the first closed path and the second closed path defined by the first endless flexible member 7 and the second endless flexible member 15. The actuators can be configured to push the thrust plate 51 against the anvil plate 53 with different thrusts between the first actuators and the second actuators, to generate a variable pressure profile along the common portion of the first closed path and the second closed path and more precisely greater in the upstream area and less in the downstream area, or vice versa. The terms “upstream” and “downstream” refer to the advancement direction of the endless flexible members 7, 15 in the area where the mutual pressure is exerted between the endless flexible members 7, 15. Therefore, the actuators 55 are located upstream of the actuators 57.

[0022] Furthermore, thrust sensors, for example load cells, are provided, configured to detect the thrust exerted by the thrust plate 51 against the anvil plate 53. For example, the thrust sensors may comprise at least a first thrust sensor 59, in the vicinity of an upstream edge of the thrust plate 51 and the anvil plate 53, and a second thrust sensor 61 in the vicinity of a downstream edge of the thrust plate 51 and the anvil plate 53. The two sensors, or sensor assemblies, are configured to detect differential thrusts of the thrust plate 51 against the anvil plate 53 along the common portion of the first closed path and the second closed path.

[0023] In some cases it is possible to have a first thrust sensor in the vicinity of an upstream edge of the thrust plate 51 and the anvil plate 53 and located on a first lateral end of one of the thrust plate 51 and the anvil plate 53 and a second thrust sensor in the vicinity of an upstream edge of the thrust plate 51 and the anvil plate 53 and locatedon a second lateral end of one of the thrust plate 51 and the anvil plate 53, located in a transverse direction with respect to the direction of the common portion of the first closed path and the second closed path.

[0024] Similarly, it is possible to have a third thrust sensor in the vicinity of a downstream edge of the thrust plate 51 and the anvil plate 53 and located on a first lateral end of one of the thrust plate 51 and the anvil plate 53 and a fourth thrust sensor in the vicinity of a downstream edge of the thrust plate 51 and the anvil plate 53 and located on a second lateral end of one of the thrust plate 51 and the anvil plate 53, located in a transverse direction with respect to the direction of the common portion of the first closed path and the second closed path. It is thereby possible to detect a non-uniform pressure between one side and the other of the ply VI or of the plies VI and V2.

[0025] Figs. 2 and 3 show schematic sections according to II-II and III-III of Fig. 1 and illustrate in an exemplary manner a possible configuration of the actuators that push the thrust plate 51 against the anvil thrust plate 53, which may be supported in a stationary manner on a load-bearing structure 60 (Fig. 1), which may have two sidewalls 60A and 60B (sidewall 60B not visible in the drawing) opposite each other and between which the endless flexible members 7 and 15 and the applicator 101 are arranged.

[0026] In the illustrated embodiment, the guide rollers 17, 19 are supported in a fixed position on the sidewalls 60A, 60B. Conversely, each of the guide rollers 11 and 13 is movably supported with respect to the fixed structure 60. More specifically, each end of the roller 11 and each end of the roller 13 is supported by a respective slide, slidable along a corresponding guide integral with the fixed structure 60 by means of respective sliding blocks. With reference to the diagram in Figs. 2 and 3, each slide is indicated with 71, the guide with 73 and the sliding blocks with 75. The arrangement is substantially the same (or symmetrical) for each of the two opposite ends of the two guide rollers 11 and 13 and therefore the same reference numbers will be used for the same components of the support and pressure means of the two guide rollers. Each slide 71 is operated by a respective actuator, in the illustrated example a cylinder-piston actuator. The actuators are each indicated with 55 (for the upstream actuators) and 57 for the downstream actuators. Each actuator is constrained in 55A, 57A to the fixed structure 60 (60A, 60B) and in 55B, 57B to the respective slide 71.

[0027] In practice, therefore, the slides 71 which support the first guide roller 11 are pushed by the actuators 55 and the slides 71 which support the second guide roller 13 are pushed by the actuators 57. The two pairs of actuators 55, 57 may be controlled independently of one another, in the sense that different thrusts may be applied to the two slides 71 of the rollers 11 and 13.

[0028] In other embodiments, the guide rollers 11, 13 may be mounted on the fixed structure and therefore arranged with fixed axes, rather than carried by the slides 71. The actuators may be connected directly to the thrust plate 51, which is pushed by the actuators 55, 57 against the anvil plate 53, while the thrust plate 51 is pushed by the actuators against the anvil plate.

[0029] In both cases the thrust actuators may be appropriately controlled to modulate and control the mutual pressure between the plate and the anvil plate.

[0030] For example, a control unit, not shown in the drawing for the sake of simplicity, as a function of the thrust value measured by the thrust sensors 59, 61, may control the two pairs of actuators 55, 57 to adjust the pressure exerted by the thrust plate 51 against the anvil plate 53. In the case of using four thrust sensors, it is possible to adjust the actuators so as to have a constant pressure along a direction transverse to the width of the plies VI, V2, i.e., in a direction transverse to the direction of the common portion of the first closed path and the second closed path, but variable along the direction of the common portion of the first closed path and the second closed path.

[0031] When the thrust plate 51 is constrained to the slides 71, the connection between the thrust plate 51 and the slides 71 may be achieved by connections that allow an angular displacement between the slides and the pressure plate, for example ball joints. For example, in the illustrated embodiment, 77 indicates connecting joints of the thrust plate 51 to each slide 71. The joints 77 allow the thrust plate 51 to be positioned slightly inclined, so that it is possible to press the thrust plate 51 against the anvil plate 53 (and therefore the endless flexible members 7, 15 therebetween) with different forces upstream and downstream with respect to the advancement path of the ply VI. Thereby, it is possible to easily impart a pressure profile that varies from the starting point to the end point of the cooperation area between pressure plate 51 and anvil plate 53.

[0032] Fig. 4 shows a second embodiment of the device 1 for bonding two plies VI, V2 by means of endless flexible members pressed against each other. Equal numbers indicate parts which are equal or equivalent to those described with reference to Figures 1, 2 and 3, and which will not be described again.

[0033] The main difference between the embodiment of Fig. 4 and the embodiment of Figs. 1 to 3 concerns the functional fluid applicator, still indicated in Fig. 4 with 101. The difference is that the applicator 101 is placed along the second advancement path P2, rather than along the first advancement path PE A guide roller 4 is located downstream of the applicator 101, which guides the web material into the nip defined between the endless flexible members 7, 15.

[0034] Fig. 5 shows a third embodiment of the device 1 for bonding two plies VI, V2 by means of endless flexible members pressed against each other. Equal numbers indicate parts which are equal or equivalent to those described with reference to Figures 1, 2, 3 and 4, and which will not be described again.

[0035] The main difference between the embodiment of Fig. 5 and the embodiment of Figs. 1 to 4 concerns the functional fluid applicator, still indicated in Fig. 5 with 101. The difference is that the applicator 101 is configured in this embodiment as a nozzle or series of nozzles 102 that spray jets J of a functional fluid onto the second ply V2 advancing along the second advancement path P2.

[0036] Fig. 6 shows a fourth embodiment of the device 1 for bonding two plies VI, V2 by means of endless flexible members pressed against each other. Equal numbers indicate parts which are equal or equivalent to those described with reference to Figures 1, 2, 3, 4 and 5, and which will not be described again.

[0037] The main difference between the embodiment of Fig. 6 and the embodiment of Fig. 5 concerns the functional fluid applicator, still indicated in Fig. 6 with 101 and comprising a series of nozzles 102 which spray jets J of a functional fluid. The difference with respect to the embodiment of Fig. 5 consists in the different position of the applicator 101, which in this case is located along the first path Pl of the first ply VI.

[0038] The arrangement described above, in the various embodiments, may be easily developed to obtain bonding of more than two plies advancing along a corresponding number of advancement paths. If necessary, a number of functional fluid applicatorsgreater than one may be provided, for example a number of functional fluid applicators equal to (N-l) where N is the number of plies to be joined together. This could, however, not be necessary, for example when the plies are sufficiently absorbent and thin to allow the passage of functional fluid through them to obtain a mutual gluing of more than two plies with a single functional fluid applicator.

[0039] For example, it is possible to envisage applying the functional fluid on the plies VI and V2 by means of functional fluid applicator devices as described so far, and to interpose a smooth or embossed third ply V3 therebetween before laminating the plies VI, V2 and V3 in the common portion of the first closed path and the second closed path in which the endless flexible members are pressed against each other in order to join the plies VI, V2 and V3.

[0040] The arrangement of endless flexible members pressed against each other along a common portion of their respective closed paths along which the endless flexible members move may also be used for the creation of a calendering device, rather than for a device for bonding two or more plies. An embodiment of a calendering device, indicated with 2, is shown in Fig. 7. Equal numbers indicate parts which are equal or equivalent to those described with reference to Figures 1 to 6. These parts will not be described again. The difference between the bonding devices of Figs. 1 to 6 and the calendering device 2 of Fig. 7 consists in the absence of a functional fluid applicator. Furthermore, in the exemplary embodiment of Fig. 7, only one path Pl is provided for the advancement of a single ply VI. Furthermore, the possibility of feeding a greater number of plies in the same calendering device 2 is not excluded, which may be fed along one or more distinct feeding paths.

[0041] The members which generate pressure between the endless flexible members 7, 15 of the calendering device 2 of Fig. 7 may be configured as described above with reference to Figs. 1, 2, 3.

[0042] In all the embodiments described above, it may be envisaged that one or both the endless flexible members 7, 15 are directly or indirectly heated. For example, in some embodiments one or both the endless flexible members may be made at least partly of a material adapted to generate induction heating, for example by means of eddy currents induced by a magnetic field while the endless flexible member is in motion.

[0043] For example, it may be provided that on the outer side of the closed path defined by one or each endless flexible member that requires heating, a layer of conductive material is made, and typically for example ferromagnetic or paramagnetic. This allows for induction heating, for example at temperatures up to 200°C, or higher, for example between 80°C and 200°C or more. Alternatively, a material suitable for induction heating may be incorporated into the material forming the endless flexible member to be heated, for example a thin sheet or foil of a few tenths of a mm or less than a tenth of a mm of aluminium or iron.

[0044] An induction heating system may be provided along the closed path of the endless flexible member to be heated, for example located inside or outside the respective closed path in a section other than the common portion of the first closed path and the second closed path.

[0045] Although the endless flexible members 7, 15 preferably have an endless outer surface 7B, 15B, the possibility of making one or other of these surfaces with longitudinal grooves is not excluded, so as to generate, in the portion of the common closed path, i.e., in the bonding or calendering nip, longitudinal bands in which the endless flexible members 7, 15 generate pressure on the plies VI, V2, and longitudinal bands in which no pressure is generated. This may be advantageous for example and in particular in the case of bonding devices 1. In this case it is advantageous for the functional fluid to be applied along longitudinal bands or strips in phase with the longitudinal bands in which the mutual pressure is generated between the two endless flexible members 7, 15.

Claims

Claims1. A device for processing an continuous cellulose web material, wherein the device comprises: at least a first advancement path for a first ply of continuous cellulose web material; along the first path:• a first endless flexible member with an inner surface inside a first closed path of the first endless flexible member and an outer surface outside the first closed path; wherein the outer surface of the first endless flexible member is approximately smooth;• a second endless flexible member having an inner surface inside a second closed path of the second endless flexible member and an outer surface outside the second closed path; wherein the outer surface of the second endless flexible member is approximately smooth; wherein the first closed path and the second closed path have a common portion, along which the first endless flexible member and the second endless flexible member advance with the outer surface of the first endless flexible member pressed against the outer surface of the second endless flexible member; wherein the first advancement path extends along the common portion, between the outer surface of the first endless flexible member and the outer surface of the second endless flexible member; and wherein first pressure members press the first endless flexible member and the second endless flexible member against each other along the common portion.

2. The device of claim 1, wherein the first pressure members comprise: a pressure plate located inside one of said first closed path and second closed path; an anvil plate located inside the other of said first closed path and second closed path; wherein the pressure plate and the anvil plate are positioned one in front of the other along the common portion of the first closed path and the second closed path; and actuators configured to push the pressure plate against the anvil plate.

3. The device of claim 2, wherein the actuators comprise first actuators and second actuators, offset along the common portion of the first closed path and the second closed path, and configured to push the thrust plate against the anvil plate withpreferably different thrusts between the first actuators and the second actuators, to generate a variable pressure profile along the common portion of the first closed path and the second closed path.

4. The device of claim 2 or 3, comprising thrust sensors, configured to detect the thrust exerted by the thrust plate against the anvil plate.

5. The device of claim 4, wherein the thrust sensors comprise at least a first thrust sensor near an upstream edge of the thrust plate and a second thrust sensor near a downstream edge of the thrust plate, to detect differential thrusts of the thrust plate against the anvil plate along the common portion of the first closed path and the second closed path.

6. The device of any one of claims 2 to 5, wherein: at least one of said first endless flexible member and second endless flexible member is guided around a first guide roller and a second guide roller, between which the common portion of the first closed path and the second closed path is defined; the first guide roller is supported by a first pair of slides guided on respective first guides, and the second guide roller is supported by a second pair of slides guided on respective second guides; the first pressure members comprise: first actuators associated with the first guide roller, and mechanically connected to the first pair of slides; and second actuators associated with the second guide roller, and mechanically connected to the second pair of slides; and the pressure plate is constrained to the first pair of slides and the second pair of slides.

7. The device of claim 6, wherein the pressure plate is constrained to the first pair of slides and the second pair of slides by means of connections that allow an angular displacement between the slides and the pressure plate.

8. The device of any one of the preceding claims, wherein the first endless flexible member and the second endless flexible member are adapted to exert a calendering action on the first ply of cellulose web material.

9. The device of any one of the preceding claims, comprising a second advancement path for a second ply of web material; wherein the first advancementpath and the second advancement path converge in the common portion of the first closed path and the second closed path.

10. The device of claim 9, further comprising a functional liquid applicator, configured to apply a functional liquid to the first ply of web material and / or the second ply of web material, upstream of the common portion of the first closed path and the second closed path.

11. The device of claim 10, wherein the functional liquid comprises a glue.

12. A method for processing a continuous web material, with a device according to any one of the preceding claims, comprising the step of feeding a continuous web material between the first endless flexible member and the second endless flexible member along the common portion of the first closed path and the second closed path; and compressing the continuous web material between the first flexible member and the second flexible member along said common portion.

13. The method of claim 12, wherein the continuous web material comprises a first ply and a second ply; wherein the first ply is fed to the common portion of the first closed path and the second closed path along a first advancement path; wherein the second ply is fed to the common portion of the first closed path and the second closed path along a second advancement path; and wherein a functional fluid is applied to one of said first ply and second ply to facilitate bonding the first ply and the second ply in the common portion of the first closed path and the second closed path.

14. The method of claim 12, wherein the web material is calendered along the common portion of the first closed path and the second closed path.

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