Rewinding machine and method for producing logs of paper material - Patents.com

Abstract

A rewinding machine for producing paper logs (20) by winding a paper web (2), the rewinding machine comprising: means for feeding the paper web (2) at a predetermined feeding speed along a predetermined feeding path (F2); web pre-cutting means (30, 31); web winding means (R2, R3, R4); and web sizing means having a pad (60) adapted to periodically apply adhesive by contacting the web, the pad (60) being attached to a pad holding device (6) connected to a corresponding actuator (61). The pad (60) is attached to the pad holding device (6) by an elastically deformable elastic support, and the pad (60) elastically moves toward the pad holding device (6) when under pressure, and automatically moves in the opposite direction to return to its previous position when the pad (60) is no longer under pressure.

Description

[Technical field]

[0001] The present invention relates to a rewinder and a method for producing a log of paper material. [Background technology]

[0002] For example, the manufacture of logs of paper material from which rolls of toilet paper or kitchen paper are obtained is known to involve feeding a web of paper formed by one or more superimposed plies onto a predetermined path along which various operations are performed before forming a log, including transverse perforation of said web to form precut lines which divide said web into cut sheets.

[0003] The formation of the logs usually involves the use of a cardboard tube, commonly called a "core", on whose surface a quantity of adhesive is distributed, thus allowing the adhesion of a paper web on the core, which is gradually introduced into a machine that produces the logs, commonly called a "rewinder". Due to its concave structure, the adhesive is applied onto the core as it passes along a corresponding path, including an end portion, commonly called a "cradle".

[0004] The formation of the logs also involves the use of a winding roller, which forces each core to rotate about its own longitudinal axis, thus determining the winding of the web on said core. The process ends when a given number of sheets have been wound on the core, by gluing a flap of the last sheet to the roll located below the roll thus formed (the so-called "flap gluing" operation).

[0005] Once a predetermined number of sheets have been wound onto the core, the last sheet of the completing log is separated from the first sheet of the next log, for example by compressed air directed at a corresponding precut line.

[0006] At this point, the log is removed from the rewinder. US Pat. No. 5,399,433 discloses a rewinder operating according to the above-mentioned operating scheme. The log is then transported to a buffer unit which feeds one or more cutters, which cut the log to obtain rolls of the desired format.

[0007] US Patent No. 5,399,633 describes a rewinder in which the application of adhesive onto the web to perform the flap bonding is performed by a roller upstream of the winding roller which alternately moves towards and away from the paper web.

[0008] Also, US Pat. No. 5,399,433 describes a rewinder in which the application of adhesive onto the web to perform the flap bonding is performed upstream of the winding roller by a diverter that periodically contacts the paper web to push it towards a fixed applicator roller arranged on the opposite side.

[0009] Also, US Pat. No. 5,399,633 discloses a system in which adhesive is applied to a paper web by deflecting the path that the web itself follows, so that, due to the deviation in the web path, the web connects with an applicator roller provided with radial pads for distributing adhesive on the paper web by contact.

[0010] US Pat. No. 5,399,633 discloses a rewinding machine with a gluing device for gluing the final edges of the logs, the gluing device being positioned and operated to dispense glue inside the winding station of the rewinding machine. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] EP 1700805 [Patent Document 2] EP 2045201 [Patent Document 3] EP 2084092B1 [Patent Document 4] GB 1167767 [Patent Document 5] US 2006 / 076450 A1 Summary of the Invention [Problem to be solved by the invention]

[0012] The main object of the present invention is to improve the adhesion of the closing flap or final edge of logs made of paper material.

[0013] It is known that, in order to create a log with optimal properties, the gluing of the first sheet of the log onto the core requires a different procedure than gluing the last sheet to complete the log. In fact, the adhesive used to glue the first sheet onto the core should preferably be relatively light, since it is necessary to keep the paper web glued to the core only during the initial stages of winding. Moreover, this adhesive should allow, when it is used, to completely remove the paper from the core to be processed, without causing damage and waste of paper.

[0014] On the contrary, the adhesive preferably used to attach the final flap or edge must be relatively hard, since it must hold the final sheet on the underlying paper layer during all steps following flap attachment, i.e., it must hold the formed log in its packaged form (with flaps properly attached) during the subsequent steps of handling, possible temporary storage and cutting of the log to obtain the paper roll that forms the final product;

[0015] Among the objects of the invention is therefore to provide a rewinding machine and a method of operation which make it possible to carry out the above mentioned operations in an optimal manner. [Means for solving the problem]

[0016] This object has been achieved according to the invention by providing a rewinder and a method for producing paper logs having the features set out in the independent claims. Further features of the invention are the subject of the dependent claims. Effect of the Invention

[0017] Among the advantages offered by the present invention, the following can be mentioned: It is possible to use adhesives of different types and / or viscosities or formulations for gluing the paper web on the core at the start of winding and for completing the final flap of the log, respectively; Extremely accurate adhesive dispensing; If a colored adhesive is used, it is possible to form a design on said web during gluing of the flaps; It is possible to reduce the risk of flap adhesive spreading uncontrollably inside the rewinder and onto the web during rewinding.

[0018] The foregoing advantages and features of the present invention will be better understood by those skilled in the art based on the following description and the accompanying drawings, which are provided as examples and should not be considered in a limiting sense. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic side view of a machine according to the invention; [Diagram 2] 2 shows a schematic diagram of a further operational configuration of an adhesive dispensing unit upstream of the winding station of the machine shown in FIG. 1; [Diagram 3] 2 is another schematic diagram of a further operational configuration of an adhesive dispensing unit upstream of the winding station of the machine shown in FIG. 1; [Figure 4] 2 is another schematic diagram of a further operational configuration of an adhesive dispensing unit upstream of the winding station of the machine shown in FIG. 1; [Diagram 5] FIG. 2 is a schematic front view of a pad holder roller according to a possible embodiment of the present invention; [Figure 6] FIG. 4 is an enlarged detail view of a pad holder roller according to a possible embodiment of the present invention. [Figure 7] FIG. 2 is a schematic side view of a pad holder roller according to a possible embodiment of the present invention. [Figure 8] FIG. 2 is a cross-sectional view of a pad holder roller according to a possible embodiment of the present invention taken along line CC. [Figure 9] FIG. 9 is a schematic perspective view of the pad holder roller produced as shown in FIGS. 5 to 8. [Figure 10] 10 is a view similar to FIG. 9 with portions of the pad and plate (602) not shown to better show the underlying spring (603). [Figure 11] 4 shows a further embodiment of a pad holder roller according to the present invention; [Figure 12] 4 is another view showing a further embodiment of a pad holder roller according to the present invention; [Figure 13] 4 is another view showing a further embodiment of a pad holder roller according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] With reference to the embodiment shown in the attached drawing, a rewinding machine (RW) for the manufacture of logs made of paper material according to the invention comprises: means (R1, R2, R5, R6, R7) for feeding a continuous web of paper material (2) along a first predetermined path; means (30, 31) adapted to make a series of discontinuous transverse cuts to divide said web (2) into tearable sheets of predetermined length; means for feeding the tubular cores (1) along a second predetermined path in which the cores (1) join the first path in correspondence with a joining channel (C) associated with the webs (2), the channel (C) being arranged upstream of a winding or log-forming station (W) in which a predetermined amount of the web (2) is wound on each of the cores (2) with a head end defining a first sheet and a tail end defining a last sheet of the log; a first sizing means adapted to release a predetermined amount of adhesive for gluing a first sheet onto the core (1) and a second sizing means adapted to release a predetermined amount of adhesive intended for gluing a last sheet of said log onto a paper layer underlying said log, i.e. for completing said log; It is a type that contains.

[0021] With regard to the embodiment shown in the drawings, the means (R1, R2, R5, R6, R7) for feeding the web (2) along a first predetermined path comprise a plurality of web guiding rollers arranged with their rotation axes parallel to one another, in particular with their respective axes oriented horizontally, according to a scheme known per se to the person skilled in the art.

[0022] One of said rollers (R2) is located in the winding station (W) and is at the same time both an end roller guiding the web (2) and a winding roller, i.e. a roller which, in cooperation with the other rollers, determines the winding of the web (2) around the core (1) which gradually reaches the winding station (W), for this reason said roller (R2) will be called "first winding roller" in the following.

[0023] With respect to the embodiment shown in the drawings, the means for providing discontinuous transverse cuts on said web (2) can consist of two cutting rollers (30, 31) with transverse axes of known kind, arranged opposite each other on either side of the path followed by said web (2) and downstream of a series of web guide rollers (R5, R6, R7) arranged upstream with respect to the direction followed by the web (2).

[0024] The web guide rollers (R5, R6, R7) can then receive the web from one or more reels arranged upstream, so that the web (2) consists of a single paper ply or of more superimposed paper plies in a known manner, which will not be described further. In the drawings, the direction of origin of the web (2) is indicated by the arrow "F2".

[0025] Thus, downstream of a pre-cut station formed by two opposing cutting rollers (30, 31) the web (2) is provided with pre-cut lines which thus allow a controlled cutting of the web which is then divided into cut-off sheets.

[0026] Also, the joining channel (C) has a substantially known structure: it is defined by a lower concave structure (C2) arranged below and opposite the first winding roller (R2), the channel (C) opens upstream, i.e. corresponding to the outlet (100b) of the device (100) for moving the core (1) described below, and it ends downstream in the winding station (W).

[0027] At the winding station (W) there are two other winding rollers (R3, R4) with horizontal axes which cooperate with the first winding roller (R2) by a mechanism known per se. In fact, by rotating about their respective longitudinal axes with a given angular speed and direction, the rollers (R2, R3, R4) determine the winding of a given amount of web (2) around each core (1) arriving at the winding station (W).

[0028] According to the embodiment shown in the drawings and according to a mechanical configuration known per se, the other two winding rollers (R3) and (R4) are located downstream of the aforementioned channel (C) and arranged opposite each other in the direction (F1) of the origin of the core (1).

[0029] According to the embodiment shown in the drawings, the rollers (R3) and (R4) are arranged on respective arms (B3, B4) connected to respective actuators (A3, A4) enabling the movement of these rollers towards and away from the destination of the core (1). The longitudinal axes of the rollers (R2, R3, R4) are parallel to each other.

[0030] According to the embodiment shown in the drawings, the first sizing means comprises an adhesive dispenser (8) arranged and acting in correspondence with a device (100) for supplying the core (1) arranged upstream of the winding station (W) and upstream of the combining channel (C).

[0031] In practice, the cores (1) are moved by a feeding device (100) of known type which transports the cores (1) to the combining channel (C), the cores coming from a core storage area (S) located upstream and constituted, for example, by a core store, a core buffer or other similar device.

[0032] For example, according to a mechanical arrangement known per se, the device (100) for feeding the cores (1) to the winding station (W) consists of a number of lower circular belts (5) arranged side by side and a number of upper fixed plates (4) also arranged side by side, which provide a lower support for the cores (1) and at the same time move them by rolling them along the aforementioned direction (F1). The reference "RF" in the drawings denotes a mechanical feeding device of known type, which picks up the cores (1) from the core storage area (S) and inserts them into the feeding device (100).

[0033] According to the embodiment shown in the drawings, the device (100) moves each core (1) downstream, passing it from an inlet (100a) to an outlet (100b) which ends in a joining channel (C) where the core (1) is joined to the head end of the portion of the web (2) from which a log is to be formed. In fact, the core (1), having already been acted upon by the adhesive dispenser (8), enters the channel (C) where the adhesive applied to itself (1) determines its joining with the first sheet or head end of the web (2) which reaches the channel, because it is dragged around the roller (R2).

[0034] The roller (R2) is provided with a mechanism (9) adapted to determine the separation of the part of the web (2) that formed the completed log from the part of the web (2) that will form the next log. For example, as known from US Pat. No. 5,999,526, the mechanism (9) can consist of a number of nozzles distributed along the length of the log provided on the inside of the roller (R2) and adapted to direct air jets through corresponding perforated parts of the roller (R2).

[0035] In the rewinder (RW) of the invention, the second sizing means is arranged and operates upstream of said joining channel (C) and comprises a roller (6) with a pad (60) adapted to release adhesive onto said web (2) by contact, said roller (6) being hereinafter referred to as the pad-carrying roller.

[0036] With reference to the embodiment shown in the drawings, the pad retaining roller (6) faces the web guide roller (R1) which guides the web (2) and thus acts as a counter support roller for the web itself when applying adhesive. The pad retaining roller (6) is parallel to the guide roller (R1) and the take-up rollers (R2, R3, R4) and is connected to respective rotation actuators (schematically indicated by reference "61" in the drawings) which control its rotation about its longitudinal axis. The circular dotted line indicated by reference "T60" in the drawings shows the circular path followed by the pad (60) when the pad retaining roller (6) is rotated.

[0037] According to the embodiment shown in the drawings, the pad (60) is a body protruding radially from the outer surface of the pad retaining roller (6), in other words, the pad (60) is a radial appendage of the retaining pad retaining roller (6).

[0038] According to the embodiment shown in the drawings, said pad retaining roller (6) is arranged and acts between the adhesive distributor (7) and the counter roller (R1).

[0039] The adhesive distribution device (7) comprises a tank (71) associated with an anilox roller (70) intended to transfer adhesive onto a pad (60). In fact, the roller (6) supporting the pad (60) is spaced from the anilox roller (70) by such a distance that determines a periodic interaction between the pad (60) and the anilox roller (70) to transfer the adhesive onto the pad itself. The pad (60), impregnated with adhesive, periodically comes into contact with the web (2) coming from the guide roller (R1) arranged upstream. The contact between the pad (60) and the web (2) is promoted by the web abutting against the roller (R1) during the contact.

[0040] The pad (60) may be monolithic and may extend longitudinally along the entire length of the roller (6), or it may be divided into several adjacent portions (60X), as shown diagrammatically in figures 7 and 9. The pad (60) may also be provided with a relief of a shape suitable for producing graphic effects on the web (2), especially if the adhesive is a pigmented adhesive.

[0041] According to the invention, it is possible to distinguish the type and / or viscosity or chemical properties of the adhesive dispensed by the first sizing means (intended to glue the web 2 onto the core 1) from the adhesive dispensed by the second sizing means (flap glue adhesive).

[0042] The first and second sizing means are synchronized with the winding means located at the winding station (W) to apply adhesive to the first sheet of the log being formed and to apply adhesive correspondingly to the last sheet of the completed log, respectively.

[0043] The application of adhesive onto the web (2) by the pad (60) is further disclosed below by providing a possible example of the use of a second sizing means.

[0044] The pad (60) extends in the longitudinal direction on the pad holding roller (6) so as to allow distribution of the adhesive over the entire width of the web (2). As mentioned above, the pad (60) may be a single body or may be divided into several parts (60X). It is therefore possible to distribute the adhesive on the web (2) both continuously and discontinuously across the web. In other words, the distribution of the adhesive on the web can also extend discontinuously across the width of the web (2).

[0045] According to the invention, the pad (60) is elastically attached to the pad-holding roller (6). For example, referring to the embodiment shown in Figures 5 to 10, the pad (60) is attached to a radial appendage (600) of the roller (6) having an inner side integral with the surface of the roller and an opposite outer side on which a bracket (601) is formed; the lower edge of the bracket hooks the lower part (60L) of the pad (60); in cross section, the pad is substantially "C" shaped, thus having an inner surface (60G) facing the bracket (601).

[0046] Between the inner surface (60G) of the pad (60) and the bracket (601) a plate (602) is arranged, below which a resilient means (603) is arranged, for example a helical spring housed in a suitable cavity (607) formed in the radial appendage (600) and oriented radially with respect to the roller (6).

[0047] Thus, depending on the compression state of the pad (60), the pad can move elastically on the appendage (600) as diagrammatically indicated by the double arrow "R60", i.e. radially or substantially radially relative to the roller (6).

[0048] Alternatively, referring to the embodiment illustrated in Figures 11 to 13, the pad (60) is mounted on an opposing plate (604), which is clamped between two holding blocks (605, 606) integrated with the pad holding roller (6). As shown in the figures, in this case the pad (60) is on the free side of said plate (opposite the side held by blocks 605, 606). Depending on the compression state of the pad (60), it can therefore move elastically with respect to the roller (6), as diagrammatically indicated by the double arrow "R60".

[0049] According to the two examples mentioned above, the pad (60) is attached to a support which, when pressure is applied to the pad (60), elastically moves towards the pad retaining roller (6) and automatically moves in the opposite direction and returns to its initial shape when the pad (60) is in an unloaded state, i.e., not under pressure.

[0050] That is, the pad (60) moves as described above because it is mounted on an elastic support. Thus, when pressure is applied to the pad, it does not have to elastically change its shape rapidly under pressure in order to maintain proper adhesive contact with the web (2), while both the pad and the web move along their own trajectories. In fact, the elastic movement of the pad (60) is controlled by the elastic support to which it is mounted, whereby no deformation of the pad (60) is required, either during contact with the web (2) or during contact with the adhesive dispenser (7).

[0051] Said pad (60) can be made, for example, of PTFE or polythene or polyethylene, ie so-called anti-adhesive plastic material having anti-adhesive properties.

[0052] Advantageously, said actuator (61) is adapted to control the rotation of said pad (6) as will be described below.

[0053] 1 to 4 show four possible steps of the manufacturing method of the present invention for producing paper logs using a sizing means.

[0054] FIG. 1 shows the pad (60) which has collected adhesive from the anilox roller (70). The transfer of adhesive from the anilox roller (70) to the pad (60) is effected by contact between the pad and the roller (70). In this process, the core (1) with the wound up paper web layer (2) is in the winding station (W), where it is rotated by the rollers (R2), (R3) and (R4) in a manner known per se and therefore not described in detail, and another core (1) already subjected to the action of the adhesive dispenser (8) is ready to be fed into the channel (C). In the winding station (W), the paper of the web (2) continues to be wound around the core (1) located between the rollers of the winding station, thereby forming a paper wrap (20) of the log being formed.

[0055] 2 shows the next process step, in which the roller (6) is provided with a pad (60) which contacts the web (2) just upstream of a perforation which separates the last sheet of a finished log from the first sheet of the next log to be produced, and in which the peripheral speed of the pad (60) is lower than the speed of the web (2) directed towards the winding station (W).

[0056] For example, the peripheral speed of the pad (60) has a value comprised between 20% and 50% of the speed of the web (2). Preferably, in this step, the peripheral speed of the pad (60) has a value comprised between 30% and 40% of the speed of the web (2), and even more preferably between 30% and 35% of the speed of the web (2). Thus, there is a longer contact between the pad (60) and the web (2), whereby the web recovers from the pad (60) all or substantially all of the adhesive that the pad previously collected from the adhesive supply device (7, 70).

[0057] Thus, at the end of this step, i.e. when the pad (60) is no longer in contact with the web (2) as the roller (6) continues to rotate, the pad (60) is substantially dry, resulting in a longer contact between the pad (60) and the web (2), which significantly reduces the risk that adhesive will drip by gravity or be centrifugally expelled from the pad, soiling the surrounding area of ​​the machine, and preparing the pad for a more complete collection of adhesive in the next step, since all or substantially all of the adhesive has been transferred from the pad (60) to the paper web (2).

[0058] In other words, after contact with the paper web, the pad (60) is dry or substantially dry, which allows the most accurate transfer of adhesive to the pad in the next step of contact with the anilox roller. This ensures high accuracy of the distribution of adhesive on the paper web during contact with the pad (60). By using the pad (60) placed on an elastic support, the transfer of adhesive from the pad to the web (2) is even better.

[0059] 3 shows the pad (60) in a standby or inoperative position upstream of the adhesive supply device (7, 70). The roller (6) thus carries the pad (60) in a position to periodically withdraw adhesive from the adhesive dispenser (7, 70), then the pad is in a position of contact with the web (2) and finally the pad is in an inoperative position so that the contact of the pad (60) with the web (2) is prolonged by the aforementioned difference between the peripheral speed of the pad (60) and the speed of the web (2) towards the winding station (W).

[0060] At the same time, the core (1) is introduced into said channel (C) and said mechanism (9) is activated, determining the separation of the sheets along the predetermined perforation line, as previously described.

[0061] FIG. 4 shows the process of collecting adhesive by the pad (60) corresponding to the anilox roll (70). When the above process is carried out, the pad (60) moves elastically because it is mounted on an elastic support. The closure of the flaps of the formed log and the removal of the log from the winding station (W) are carried out in a manner known to those skilled in the art and will therefore not be described in more detail.

[0062] At this stage, the head end of the first sheet of the next log to be formed comes into contact with the core (1) on which the next log is to be formed and is bonded to it due to the adhesive previously applied thereon. In fact, the web is interrupted by the action of the mechanism formed by the nozzle (9), and the web ends thus obtained constitute respectively the tail end used to close the flaps of the formed log and the head end for the start of winding the web on the core of the new log to be formed.

[0063] As mentioned above, the processes of preparing the web (2) for winding on a core (1) and winding the web on said core in machines of the above type are known to those skilled in the art. The web (2) passes through a series of web guide rollers (R5, R6, R7) until it reaches a pre-cut station which includes cutting rollers (30, 31) which create a series of pre-cut lines on the web (2) which divide it into cut sheets.

[0064] one of said precut lines is used by the nozzle (9) of said winding station (W) to separate the tail portion of the downstream web (which defines the closing flap of the finished log) from the head portion of the upstream web (which is glued to the core of the next log to be formed); The cores (1) are moved by a device (100) which conveys them towards a joining channel (C); in moving through the device (100), each core (1) is acted upon by an adhesive dispenser (8) via a set of adhesive dispensing nozzles (80); According to the embodiment shown in the drawings, said adhesive dispenser (8) represents said first sizing means for applying adhesive, i.e. means for distributing adhesive intended to glue said webs (2) onto said core (1); Once the core (1) enters the channel (C), the web is pulled around the roller (R2) so that the adhesive distributed on the core (1) determines the bond between the first sheet or head end of the web that arrives in the channel and the core; In the above-mentioned embodiment, the roller (R2) is equipped with a web disturbance mechanism, which is formed by a nozzle (9) provided inside the roller (R2) as described in the above-mentioned embodiment and adapted to determine the separation between the part of the web (2) that formed the completed log and the part of the web (2) that will form the next log.

[0065] More generally, the invention is applicable to rewinding machines having the following configuration: - feeding means (R1, R5, R6, R7) for feeding a continuous paper web (2) along a predetermined feeding path (F2) for feeding the paper web (2) at a predetermined feeding speed; - pre-cutting means (30, 31) adapted to provide a series of pre-cut discontinuous transverse lines for dividing said web (2) into sheets of predetermined length; - winding means (R2, R3, R4) arranged in a winding station (W) arranged downstream of said web supply device and adapted to wind said web (2) to produce logs (20) of paper material; and - a sizing means arranged upstream of said winding station (W) and adapted to act along said feed path (F2) of said web (2) and to periodically apply glue by contacting said web (2) in the vicinity of its precut line, said pad (60) being adapted to be mounted on a pad holding device (6) connected with a corresponding actuator (61); Including, a rewinder, in which the pad (60) is attached to the pad retaining device (6) by means of an elastic support which deforms elastically, such that the pad (60) moves elastically towards the pad retaining device (6) when it is subjected to pressure and moves elastically towards the pad retaining device (6) and automatically moves in the opposite direction back to its previous position when the pad (60) is no longer subjected to pressure.

[0066] Preferably, when the pad (60) is in contact with the web (2), the pad (60) is moved by the pad retaining device (6) at a speed lower than the speed at which the web (2) is fed along the respective feed path (F2), thereby determining a long contact time between the pad (60) and the web (2) while both the pad (60) and the web (2) are moving.

[0067] Preferably, the speed of the pad (60) in contact with the web (2) is between 20% and 50% of the speed of the web (2). More preferably, in this step, the peripheral speed of the pad (60) is between 30% and 40% of the speed of the web (2), and even more preferably, is between 30% and 35% of the speed of the web (2).

[0068] Advantageously, said pad retaining devices (6) are rollers adapted to rotate about their respective longitudinal axes under the control of respective actuators (61).

[0069] Furthermore, advantageously, when the pad (60) contacts the web (2), the web abuts against a roller (R1) disposed along the aforementioned feed path (F2) of the web (2).

[0070] The present invention is applicable both to rewinding machines that use a tubular core (1) to produce logs (20), and to rewinding machines that produce "coreless" type logs, i.e., logs without an inner core.

[0071] If the rewinder (RW) is of the type that uses cores (1) to create logs, according to the above-mentioned embodiment, it is preferably equipped with the following components: - means adapted to feed said tubular core (1) along another predetermined path (F1) which joins with said first path (F2) in a joining channel (C) associated with said web (2), said channel (C) terminating at said winding station (W); - means (8) for distributing adhesive onto said cores, adapted to release adhesive onto each core (1) along said further path (F1);

[0072] From the above description it can be seen that the method for producing a log of paper material according to the invention comprises the following steps: - feeding the continuous paper web (2) at a predetermined feed speed along a corresponding predetermined web feed path (F2); - providing a series of pre-cut discontinuous transverse lines for dividing said web (2) into sheets of predetermined length which are separated by tearing; - winding the web (2) into paper logs (20) at a winding station (W); - providing a sizing means along said web feed path (F2) with an adhesive application pad (60) capable of periodically applying adhesive by contacting said web (2) in the vicinity of its precut line and mounted on a pad holding device (6); and - the pad (60) is attached to the pad retaining device (6) by means of an elastic support which is elastically deformable, so that the pad (60) moves elastically towards the pad retaining device (6) when it is subjected to pressure, and moves in the opposite direction automatically returning to its previous position when the pad (60) is no longer subjected to pressure.

[0073] According to a preferred embodiment of the method outlined above, when the pad (60) is in contact with the web (2), the pad (60) is moved by the pad retaining device (6) at a speed lower than the speed at which the web (2) is fed along its respective feed path (F2) in order to determine the extended contact time of the pad (60) with the web (2) while both the pad (60) and the web (2) are moving.

[0074] Preferably, the speed of the pad (60) in the step of contacting the web (2) is between 20% and 50% of the speed of the web (2). More preferably, the peripheral speed of the pad (60) in this step is between 30% and 40% of the speed of the web (2), and even more preferably, is between 30% and 35% of the speed of the web (2).

[0075] According to an embodiment which foresees the use of said tubular core (1) for manufacturing said log (20), the method according to the invention also comprises the following steps: - feeding said tubular cores (1) along another predetermined path (F1) which merges with said web feeding path (F2) in correspondence with a combining channel (C) located upstream of said winding station (W) where said tubular cores (1) are associated with said webs (2) and where a predetermined amount of said web is wound on each of said cores (1); - distributing adhesive onto each core (1) by separate adhesive distributing means (8); - providing said further adhesive dispensing means along said further predetermined path upstream of said joining channel (C).

[0076] According to the embodiment shown in the drawings, a sizing means intended to apply adhesive to the web (2) upstream of the winding station (W) is arranged at a given distance from said winding station at a point before the web (2) has yet reached said winding station, i.e. the first winding roller (R2).

[0077] In practice, however, details of implementation may be modified in an equivalent manner with respect to the individual elements described and illustrated and their mutual arrangement, without going beyond the scope of the concept of the solution adopted and therefore within the scope of the protection granted by this patent in accordance with the following claims.

Claims

1. A rewinding machine (RW) for producing paper logs (20) obtained by winding a paper web (2), comprising: The rewinder is: - feeding means (R1, R5, R6, R7) for feeding a continuous paper web (2) along a predetermined feeding path (F2) for feeding the paper web (2) at a predetermined feeding speed; - pre-cutting means (30, 31) adapted to provide a series of pre-cut discontinuous transverse lines for dividing said web (2) into sheets of predetermined length; - winding means (R2, R3, R4) arranged in a winding station (W) arranged downstream of the supply means of said web and adapted to wind said web (2) in order to produce logs (20) of paper material; - sizing means arranged and acting along the feed path (F2) of the web (2), upstream of said winding station (W), comprising an adhesive application pad (60) adapted to periodically apply adhesive to the web (2) by contacting it in the vicinity of its precut line, said pad (60) being adapted to be mounted on a pad holding device (6) connected to a corresponding actuator (61); Including, - a rewinding machine, characterized in that the pad (60) is attached to the pad holding device (6) by means of an elastic support which is elastically deformable, and by means of the elastic support, when the pad (60) is subjected to pressure, the pad (60) moves elastically towards the pad holding device (6) and, when the pad (60) is no longer subjected to pressure, the pad (60) automatically moves in the opposite direction to return to its previous position.

2. 2. The rewinder of claim 1, wherein the pad (60) is attached to a spring (603).

3. 2. The rewinder of claim 1, wherein the pad (60) is mounted on a flexible plate (604).

4. 2. The rewinding machine according to claim 1, characterized in that the pad holding devices (6) are controlled by each of the actuators (61) so that when the pad (60) comes into contact with the web (2), the pad (60) is moved by the pad holding devices (6) along the web supply path (F2) at a speed lower than the supply speed of the web (2), so that the pad (60) and the web (2) are kept in contact for a long period of time while the pad (60) and the web (2) are moving.

5. 5. Rewinder according to claim 4, characterized in that the speed of the pad (60) in contact with the web (2) has a value comprised between 20% and 50% of the feed speed of the web (2).

6. A rewinding machine as described in claim 4, characterized in that the speed of the pad (60) contacting the web (2) has a value between 30% and 40% of the feed speed of the web (2).

7. A rewinding machine as described in claim 4, characterized in that the speed of the pad (60) contacting the web (2) has a value between 30% and 35% of the feed speed of the web (2).

8. said pad retaining devices (6) being rollers adapted to rotate about corresponding longitudinal axes under the control of each of said actuators (61); 2. The rewinder of claim 1, wherein said pad (60) projects radially from said roller.

9. 2. A rewinder as claimed in claim 1, characterised in that it comprises a roller (R1) arranged along the feed path (F2), on which the web (2) rests while in contact with the pad (60).

10. The rewinding machine includes: - means for feeding a tubular core (1) along another predetermined path (F1) which joins said feeding path (F2) at a joining channel (C), said tubular core (1) being associated with said web (2) and said joining channel (C) terminating at said winding station (W); and - core sizing means (8) adapted to release adhesive onto each core (1) along said separate predetermined path (F1); The rewinder according to any one of claims 1 to 9, further comprising:

11. - feeding a continuous paper web (2) at a predetermined feed speed along a predetermined web feed path (F2); - providing a series of pre-cut discontinuous transverse lines for dividing said web (2) into sheets of predetermined length to be separated by tearing; - winding the web (2) into paper logs (20) at a winding station (W); and - providing, along said web feed path (F2), a sizing means capable of periodically applying adhesive by contacting said web (2) in the vicinity of its precut line, and comprising an adhesive application pad (60) mounted on a pad holder (6) by means of an elastic support which is elastically deformable; - a method for manufacturing a paper material log, characterized in that said pad (60) moves resiliently relative to said pad holding device (6) by means of said elastic support.

12. 12. The method according to claim 11, characterized in that when the pad (60) comes into contact with the web (2), the pad (60) is moved by the pad holding device (6) at a speed lower than the speed at which the web (2) is fed along each of the feed paths (F2), so that a long contact time between the pad (60) and the web (2) is determined while both the pad (60) and the web (2) are moving.

13. 12. The method according to claim 11, characterized in that the speed of the pad (60) in contact with the web (2) has a value comprised between 20% and 50% of the feed speed of the web (2).

14. The method described in claim 11, characterized in that the speed of the pad (60) contacting the web (2) has a value comprised between 30% and 40% of the feed speed of the web (2).

15. The method described in claim 11, characterized in that the speed of the pad (60) contacting the web (2) has a value comprised between 30% and 35% of the feed speed of the web (2).

16. - feeding tubular cores (1) along another predetermined path (F1) which joins with said web feeding path (F2) at a joining channel (C), said tubular cores (1) being associated with said webs (2), said joining channel (C) being arranged upstream of said winding station (W) where a predetermined amount of said web is wound onto each of said cores (1); - dispensing adhesive onto each core (1) by separate adhesive dispensing means (8); and - providing said further adhesive discharge means upstream of said joining channel (C) and along said further predetermined path; 12. The method of claim 11 further comprising the steps of:

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