Device for adjusting and equalizing tension in web material and single facer comprising said device

Abstract

The device of the present application comprises a roller (55) for guiding a web of material (N1, N2), which is idling supported about an axis of rotation (55X) and has a first axial end and a second axial end. Two lateral supports (59A, 59B) support the guide roller. The guide roller is configured such that its axis of rotation may be tilted with respect to a position orthogonal to the direction of advancement of the web material to compensate for variations in tension on the web material in the transverse direction.

Description

Technical Field

[0001] The present invention relates to machines for processing continuous web-like materials. More specifically, embodiments disclosed herein relate to machines for producing corrugated board and components thereof. In this specific case, the present invention relates to improvements in so-called single-facer machines and components thereof. Background Art

[0002] Corrugated board is manufactured starting with a smooth paper web unwound from a suitable reel. In its simplest form, corrugated board consists of a smooth web and a corrugated web, bonded together along the ridges of the corrugated webs. The web of paperboard thus formed is known in the industry as single facer. Often, a second smooth web is added to this basic structure, bonded to the corrugated web so that the corrugated web is sandwiched between the two smooth webs, also known as a liner. In some cases, in addition to this three-web structure, there are also structures with a sequence of corrugated webs sandwiched between the smooth webs.

[0003] Single-faced paperboard is produced by a single-facer, which includes a pair of intermeshing corrugating rollers, between which a first smooth paper web is supplied. The first smooth paper web enters the nip between the two corrugating rollers after thermal deformation to become a corrugated paper web. Adhesive is applied to the ridges of the corrugated paper web engaged with one of the corrugating rollers, and the smooth paper web is applied under pressure and heat on the corrugated paper web provided with the adhesive.

[0004] A pressure unit comprising at least one pressure member pressed against one of the corrugating rollers is used to bond the corrugated paper web and the smooth paper web to each other. The smooth paper web and the corrugated paper web pass between the corrugating roller and the pressure member.

[0005] Examples of single-sided machines are disclosed in US10,618,242, US8,714,223 and WO2021224142.

[0006] The paper web supplied to the single facer is usually guided around a dancer roller which is used to keep the supply tension constant and absorb speed fluctuations. The dancer roller is usually supported idly by a pair of pivot arms and pressure is applied by an actuator to keep the tension of the paper web guided around the dancer roller constant.

[0007] Furthermore, equalizing means are usually provided, the purpose of which is to keep the tension of the web uniform in the transverse direction, which is orthogonal to the direction of advancement of the web along the supply path. In other words, means are usually provided to make the tension along the right longitudinal edge of the web substantially uniform with the tension along the left longitudinal edge. For this purpose, equalizer rollers are usually used in association with various mechanisms for equalizing the tension on both sides of the web. The uniformity of the tension along the width of the web is very important to maintain the correct guidance of the web in order to obtain a good quality product. In fact, uneven tension in the transverse direction can lead to variations in the pressure with which the web is pressed against the heating roller or heating plate. This pressure difference can lead to different amounts of heat being transferred to the web, thus creating an unwanted temperature gradient in the transverse direction, i.e. in the direction of the width of the web. This pressure difference can lead to uneven bonding of the corrugated board in the width direction at the exit of the single-facer, or even to imperfect flatness of the board.

[0008] Examples of devices for equalizing web tension are disclosed in EP0888993, EP0803458, US5,419,509, US6,206,995, US5,971,313, JP2004-35140, US5,730,693.

[0009] EP1190843 discloses a device for absorbing tension fluctuations on a paper web in a corrugated board production plant. GB2170784 discloses another system for controlling the tension of a paper web.

[0010] To control tension and advance speed, as well as tension damping and speed variations over time, while equalizing tension in the cross direction, ie across the width of the web, requires a large number of components and mechanical structures along the paper feed path.

[0011] It would therefore be advantageous to be able to provide a simpler system with fewer components to perform the various functions of controlling web tension, particularly in single facers for producing corrugated board. Summary of the invention

[0012] In order to overcome or reduce the disadvantages of the prior art, a novel device for adjusting and equalizing the tension of a continuous web material supplied along a supply path is disclosed herein.

[0013] In one embodiment, the device for adjusting and equalizing the tension of a continuous web material comprises a roller for guiding the web material, the roller being idly supported by a first lateral support and a second lateral support about a rotation axis. The first lateral support and the second lateral support are movable along an axis for adjusting the tension of the web material. The guide roller, the first lateral support and the second lateral support are configured so that the rotation axis of the guide roller is pushed to change the inclination relative to the tension adjustment axis due to a change in the tension of the web material in a direction transverse to the advancing direction of the web material.

[0014] In the embodiments described herein, more specifically, the device comprises a path for supplying web material, and a roller guiding the web material along the path. The guide roller is supported idling around an axis of rotation. The roller is directly or indirectly constrained to a first lateral support and a second lateral support. The first lateral support and the second lateral support have a movement for adjusting the tension of the web material relative to the load-bearing structure according to a tension adjustment axis. In an advantageous embodiment, the tension adjustment axis is a pivot axis orthogonal to the advancement direction of the web material, and the first support and the second support are arms pivoting around the pivot axis. It is not excluded that the support can perform a translational movement along the adjustment axis instead of a pivotal movement, in which case the adjustment axis is not a pivot axis, but a translation axis located in a plane orthogonal to the guide roller axis.

[0015] The device also includes at least one first actuator associated with the first lateral support and the second lateral support to control the movement of the first lateral support and the second lateral support for adjusting the tension. In some embodiments, a first actuator associated with the first lateral support and a second actuator associated with the second lateral support are provided. The word actuator can generally be used to refer to any member suitable for applying an action to control or command the position of the lateral support of the guide roller. For example, the actuator can consist of a cylinder-piston system as a pneumatic spring.

[0016] Advantageously, the guide roller is supported so that a tension difference of the web material in a direction transverse to the direction in which the web material is supplied (i.e. in the width direction of the web material) causes the rotation axis of the guide roller to be passively tilted to adapt to the tension of the paper, thereby causing the tension on the side with greater tension to decrease and the tension on the side with less tension to increase. In other embodiments, the possibility of actively controlling the inclination of the roller to compensate for tension variations in the transverse direction is not excluded.

[0017] By means of this arrangement, a single guide roller can control the tension and / or speed of the web material, possibly absorb tension peaks, and equalize the tension in the transverse direction, ie across the width of the web material.

[0018] Further advantageous embodiments of the device for adjusting and equalizing tension will be described below with reference to the accompanying drawings and defined in the appended claims.

[0019] Another object of the present invention is to provide a single facer for producing corrugated board, the single facer comprising a first path for feeding a first paper web and a second path for feeding a second paper web. The single facer also comprises a first corrugating roller and a second corrugating roller, which mutually define a corrugating nip for corrugating the first paper web. The first supply path passes through the corrugating nip. The pressure member defines a pressure nip together with the first corrugating roller, through which the first supply path and the second supply path extend. The single facer also comprises at least one device for adjusting and equalizing the tension of a web material of the above type on at least one of the first supply path and the second supply path. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will become more apparent from the description and the accompanying drawings, which describe embodiments of the present invention by way of non-limiting examples of the present invention. More specifically, in the drawings:

[0021] Figure 1 is a schematic side view of a single facer including means for regulating and equalizing the tension of a paper web supplied to a corrugating roller;

[0022] Figure 2 is a cross-sectional view taken along a vertical plane parallel to the axis of the corrugating roller of the apparatus for adjusting and equalizing tension in one embodiment;

[0023] Figure 3 is based on Figure 2 A view taken from III-III;

[0024] Figure 4 is based on Figure 2 A cross-sectional view taken along line IV-IV;

[0025] Figure 5 is another embodiment of a device for adjusting and balancing tension. Figure 2 A cross-sectional view similar to a cross-sectional view;

[0026] Figure 6 is based on Figure 5 VI-VI intercepted view;

[0027] Figure 7 is another embodiment of a device for adjusting and balancing tension. Figure 2 A cross-sectional view similar to a cross-sectional view;

[0028] Figure 8 is based on Figure 7 A view taken from VIII-VIII of FIG.

[0029] Fig. 9 is another embodiment of a device for adjusting and balancing tension. Figure 2 a cross-sectional view similar to that of FIG.

[0030] Fig.10 It is a cross-sectional view taken along a plane orthogonal to the rotation axis of the guide roller. DETAILED DESCRIPTION

[0031] Figure 1 An exemplary embodiment of a single-facer 1 is schematically shown, in which the content disclosed in the present invention may be included. It should be noted that the structure of the single-facer can also be different from the structure shown in the figure, for example, with respect to the pressure system for connecting the corrugated paper web with the smooth paper web, the preheating system and any other aspects, while being consistent with the characteristics of the system for controlling and equalizing the tension of the paper web described below.

[0032] exist Figure 1 In the embodiment of the present invention, the single-facer 1 comprises a load-bearing structure 3 which is connected to a bridge 5 along which the single-faced sheets NS formed by the single-facer 1 are conveyed to other processing stations not shown, such as a double-facer.

[0033] The single facer 1 comprises a first supply path P1 for supplying a first paper web N1 from a first unwinding device (not shown). The single facer 1 further comprises a second supply path P2 for supplying a second paper web N2 from a second unwinding device (not shown). The first paper web N1 forms the corrugated sheet of the single facer NS coming out of the single facer 1, while the second paper web N2 forms the smooth cover of the single facer NS.

[0034] The single-faced paperboard NS produced by the single-facer 1 is supplied to the bridge 5 by the lifting device 7, and then the single-faced paperboard NS is supplied from the bridge to the double-facer to be bonded with other single-faced paperboard webs and / or second liners from other single-facers to form a corrugated board with one or more corrugations. In other embodiments, the single-faced paperboard web is directly cut into sheets or rolled into reels, or gathered into flaps.

[0035] The single-facer 1 comprises a first corrugating roller 9 and a second corrugating roller 11 which cooperate with each other to form a corrugating nip through which a path for supplying a first paper web N1 extends to permanently deform to form flutes. A supply path P1 extends through the corrugating nip between the corrugating rollers 9 and 11 and between the corrugating rollers 9 and an adhesive dispenser 13 adapted to apply adhesive to the flute ridges formed on the first paper web N1. The adhesive dispenser 13 is arranged adjacent to the first corrugating roller 9, downstream of the corrugating nip in the advancing direction of the paper web N1, and cooperates with the first corrugating roller 9. More precisely, the adhesive dispenser 13 is arranged between the corrugating nip defined by the corrugating rollers 9 and 11 and a pressure member 15 which cooperates with the first corrugating roller 9 and defines a pressure nip together with the first corrugating roller for bonding the two paper webs N1 and N2 to each other.

[0036] exist Figure 1 In the embodiment of the present invention, the pressure member 15 comprises a continuous flexible member 15.1 guided between two guide rollers 15.2 and 15.3. An actuator member (not shown) presses the continuous flexible member 15.1 against the cylindrical surface of the first corrugating roller 9. In other embodiments, the configuration of the pressure member may be different, for example, it may comprise a single pressure roller.

[0037] The second supply path P2 extends through the pressure nip between the pressure member 15 and the first corrugating roller 9 so that the first paper web N1 and the second paper web N2 are bonded to each other by the adhesive applied by the adhesive dispenser 13 to pass between the first corrugating roller 9 and the pressure member 15. The paper webs N1 and N2 are bonded by the pressure and heat. For this purpose, the paper webs N1 and N2 are preheated before being supplied to the corrugating rollers 9, 11. In addition, the corrugating rollers 9 and 11 can also be heated in turn to transfer heat to the paper webs N1 and N2. For example, the heating can be obtained by saturated steam or superheated steam circulating in the corrugating rollers 9, 11, or by any other suitable heat source.

[0038] In the illustrated embodiment, a first heating system 21 is arranged along the first supply path P1 for preheating the first paper web N1 before it comes into contact with the corrugating rollers 9 and 11. Similarly, a second heating system 23 is arranged along the second supply path P2 for preheating the second paper web N2 before it comes into contact with the first corrugating roller 9 and the pressure member 15.

[0039] In some embodiments, the first heating system 21 and the second heating system 23 each include at least one fixed heating plate, preferably two fixed heating plates, on which the corresponding paper web N1 or N2 slides. In other embodiments, a preheating roller can be used instead of a fixed heating plate, or in combination with a fixed heating plate.

[0040] More specifically, in Figure 1 In the illustrated embodiment, the first heating system 21 comprises a first heating plate 25 and a second heating plate 29 . The second heating system 23 comprises a third heating plate 27 and a fourth heating plate 33 .

[0041] In the illustrated embodiment, the first heating system 21 may further include a fifth heating plate 31 , and the second heating system 23 may include a sixth heating plate 35 .

[0042] In the illustrated embodiment, the second heating system 23 further includes a heating roller 37 along the second supply path P2.

[0043] In an advantageous embodiment, each heating element 25, 27, 29, 31, 33, 35, 37 may comprise known adjustment means for adjusting the contact arc between the respective web N1 or N2 and the heating element. For example, such adjustment means may comprise a guide roller which changes the contact arc between the web and a heating roller, such as roller 37, to which guide rollers 39A and 39B are associated. When the heating device is a heating plate, it may have an adjustable inclination in order to change the contact arc between the web and the active surface of the heating plate.

[0044] In an advantageous embodiment, a device for adjusting and equalizing the tension may be provided in one or both paths P1, P2, which device has several functions, in particular: absorbing (i.e. dampening) the tension variations of the web; absorbing (i.e. dampening) the variations in the web feeding speed; and finally, equalizing the tension of the web in the transverse direction, i.e. ensuring that the tension along the transverse extension of the web is approximately constant, so that the tension along the right longitudinal edge is substantially approximately the same as the tension along the left edge of the web. This helps to keep the web correctly guided along its path and to obtain uniform heating.

[0045] As will become apparent from the following detailed description of various embodiments, the system provided according to the invention can, for a single web, perform all these functions by a single web-guiding roller suitably supported by lateral supports, such as pivot arms.

[0046] exist Figure 1 In the embodiment of the present invention, a first device 53 for adjusting and equalizing the tension of the paper web N1 is inserted on the supply path P1. In the embodiment shown, the device 53 for adjusting and equalizing the tension is arranged between the heating plate 31 and the heating plate 29.

[0047] exist Figure 1In the embodiment of the invention, a device for adjusting and equalizing the tension is also provided along the second supply path P2 of the paper web N2. The device for adjusting and equalizing the tension of the paper web N2 is again indicated by 53, because the two devices for adjusting and equalizing the tension can be identical, or can be arranged in a mirrored manner, or more generally, they can perform the same function, although the configuration may be different, for example according to two different embodiments selected from the embodiments described in detail below.

[0048] Each device 53 for adjusting and equalizing tension generally comprises: a guide roller 55; a pair of pivoting arms 57 supporting the respective guide rollers 55; one or two actuators 59 acting on the pivoting arms 57. As described in more detail with reference to the following figures, an encoder may also be associated with one or both pivoting arms 57, which show various embodiments of the device 53 for adjusting and equalizing tension.

[0049] Reference numeral 100 denotes a control unit which may be functionally connected to actuators and / or encoders or other position sensors associated with these two devices for regulating and equalizing tension.

[0050] It should be noted that the number of devices for adjusting and balancing tension may be different from that shown in the figure. For example, one of the two paths may not have a device for adjusting and balancing tension, or more than two devices for adjusting and balancing tension may be provided.

[0051] In the following, considering that the device 53 for adjusting and balancing the tension can be used in other occasions where similar problems may arise and it is necessary to adjust and balance the tension of continuous web materials, when describing each device 53 for adjusting and balancing the tension, reference will be made to general web materials rather than specific reference to paper webs N1 and / or N2. Figures 2 to 4 Example

[0052] on the whole, Figures 2 to 4 A device 53 for adjusting and equalizing tension is shown, which device comprises a guide roller for guiding a web material, which guide roller is supported idlingly about an axis of rotation. The guide roller is supported by two arms pivoting about a common pivot axis. The axis of rotation forms an axis for adjusting the tension of the web material. In other words, the tension of a web material, for example web N1 or web N2, can be kept at approximately a constant value by pivoting a pivot arm and thereby moving the guide roller supported by said pivot arm. An actuator associated with at least one of the pivot arms controls the angular position of the pivot arm, and the pivot arms can be connected to each other by a torsion bar so that a movement applied to one of the pivot arms is transmitted to the other pivot arm.

[0053] In certain embodiments, an actuator is provided for each of the two pivot arms.

[0054] In order to ensure that the tension difference along the supply path in a direction transverse to the supply direction of the web material causes the pivoting of the rotation axis of the guide roller to compensate for and tend to eliminate this tension difference and thereby balance the tension, the guide roller is supported at a first axial end by a first pivot arm and at a second axial end by a second pivot arm, for example by a spherical bearing or a spherical joint, which can change the orientation of the rotation axis of the guide roller relative to the pivot arm.

[0055] Furthermore, the two pivot arms are mutually constrained by a torsion bar, the connection of which allows an angular displacement of the two pivot arms relative to each other, ie an angular staggering of the two pivot arms about the pivot axis. This angular staggering results in a change in the inclination of the axis of rotation of the guide roller relative to the two pivot arms.

[0056] Basically, this arrangement is such that the tension difference between the two longitudinal edges of the web material (i.e. the tension variation in the transverse direction) leads to an angular staggering of the two pivot arms and a consequent change in the inclination of the axis of rotation of the guide roller. The change in inclination causes the position of the axis of rotation to be non-orthogonal to the advancing direction of the web material, thereby generating tension compensation, i.e. an equilibrium between the tensions on both longitudinal sides of the web material.

[0057] Now, referring to the accompanying drawings, Figure 2 3A and 3B denote two side parts which are part of the load-bearing structure 3, between which a device 53 for adjusting and equalizing tension is arranged. A first pivot arm is denoted by 57A, which is articulated to the side part 3A so as to pivot about a pivot axis XX which forms an axis for adjusting the tension of the web material. A second pivot arm is denoted by 57B, which is articulated to the side part 3B so as to pivot about a pivot axis XX.

[0058] The pivot arms 57A, 57B support a guide roller, again denoted by 55. The guide roller 55 is idlingly supported on the pivot arms 57A and 57B. To this end, the guide roller 55 has two tangs 153A and 153B, which are respectively at a first axial end and a second axial end of the guide roller 55. The first tang 151A is supported by a first spherical bearing 155A, which is accommodated in a seat integrally connected to the first pivot arm 57A. The second tang 151A is supported by a second spherical bearing 155B, which is accommodated in a seat integrally connected to the second pivot arm 57B. The expression spherical bearing is generally used to indicate a bearing that enables the guide roller 55 to rotate about its axis of rotation 55X and to change the inclination of the axis of rotation 55X.

[0059] In this arrangement, the rotation axis 55X of the guide roller 55 can adopt an angular position that can be changed relative to the pivot axis XX of the first pivot arm 57A and the second pivot arm 57B. As described below, if the tension of the web material guided around the guide roller 55 is constant in the transverse direction, i.e. parallel to the axis 55X, then the axis should be parallel to the pivot axis XX of the pivot arms 57A, 57B. On the other hand, if the tension on the web material advancing according to the arrow F is uneven, i.e. greater on one of the left and right sides of the web material and smaller on the other side, the inclination of the axis 55X will be changed to equalize the tension, i.e. it will make the side of the web material with greater stretch looser and the side with less stretch stretch.

[0060] The change in inclination of axis 55X is a direct result of the tension difference in the transverse direction.

[0061] In order to be able to vary the inclination of axis 55X, the two pivot arms 57A, 57B are interconnected by a torsion bar 157 coaxial with pivot axis XX, which is connected to the first pivot arm 57A and the second pivot arm 57B so that the two pivot arms can be angularly staggered relative to each other about axis XX.

[0062] To this end, in the embodiment shown, the torsion bar 157 is rigidly connected to the pivot arm 57A so as to be rigidly rotatable together with the pivot arm about the axis XX. On the other hand, the torsion bar 157 is connected to the pivot arm 57B in such a way that an angular play is left between the torsion bar 157 and the pivot arm 57B. The possibility is not excluded that the connection between the torsion bar 157 and the pivot arm 57A is also such as to achieve a mutual angular staggering between the torsion bar 157 and the pivot arm 57A.

[0063] In the embodiment shown, in particular Figure 4 As shown, this angular staggering capability between the torsion bar 157 and the pivot arm 57B is obtained in the following manner. The end 157A of the torsion bar 157 is housed in a ring 159 integrally connected to the pivot arm 57B. A key 161 is integrally connected at the end 157A of the torsion bar 157, and the key is housed in a seat 163 formed in the ring 159. The tangential dimension of the seat 163 is greater than the width of the key 161 in the tangential direction, so that the pivot arm 57B can rotate about the axis XX relative to the torsion bar 157 and thus relative to the pivot arm 57B by an angle defined by the gap between the key 161 and the seat 163.

[0064] When the tension of the web material N1, N2 guided around the guide roller 55 is equal along the axial extension of the guide roller 55, the two pivot arms 57A, 57B are angularly phased relative to each other, the axis 55X of the guide roller 55 being parallel to the pivot axis XX. On the other hand, when the tension to which the web material N1, N2 is subjected changes in the transverse direction for any reason, the two pivot arms 57A, 57B are angularly staggered, resulting in an inclination of the axis 55X relative to the axis XX. This inclination rebalances the tension of the web material in the transverse direction.

[0065] In addition to this tension equalization effect, the device 53 also has the function of absorbing fluctuations in the longitudinal tension of the web material N1, N2, so that the guide roller 55 operates as a dancer roller. If fluctuations occur due to changes in speed or tension, which can be detected by any known system, for example by a load cell on the support of one of the rollers around which the web material N1, N2 is guided, the pivoting arms 57A, 57B are pivoted by one or a pair of actuators. In the embodiment shown, the actuator 59A is associated with the pivoting arm 57A and the actuator 59B is associated with the pivoting arm 57B. The movements applied by the two actuators 59A, 59B can be controlled by the central control unit 100.

[0066] In other embodiments, and presently preferred embodiments, the actuators 59A, 59B may be operated to maintain a constant tension on the web material N1, N2. In these embodiments, the actuators 59A, 59B are preferably pneumatic actuators, which may act as simple pneumatic springs, or they may be generally configured to maintain a substantially constant tension on the web material N1, N2. In this case, if the tension of the web material guided around the guide roller 55 changes, the actuators 59A, 59B will ensure that the position of the guide roller 55 changes in a direction that tends to eliminate the tension variation. Typically, if the tension tends to increase, the actuators 59A, 59B (or a single actuator if only one actuator is provided) will cause the roller 55 to be displaced in a direction that reduces the path of the web material N1, N2. In the case of a decrease in tension, the opposite situation occurs (the path increases). Basically, the rotation of the arms 57A and 57B is a result of the tension variation, and the direction of rotation tends to eliminate the tension variation.

[0067] The displacement of the arm can be detected by a position sensor or detector (i.e. encoder), which causes a change in the machine operating conditions through the central unit 100, such as an increase or decrease in the forward speed of the web material N1, N2, which tends to return the guide roller 55 and thus the arm 57A, 57B to the initial position.

[0068] For example, the central control unit 100 can be programmed to vary the tension or speed of the supplied paper web N1 or N2 depending on the position of the corresponding guide roller 55 using a control loop which tends to maintain the position of the guide roller 55, and thereby the position of the pivoting arms 57A, 57B, around a predetermined position. The position of the arm can be read, for example, by an encoder 167 associated with the pivoting arm 57B.

[0069] In summary, through a single guide roller 55, the device 53 for adjusting and equalizing the tension can implement the function of adjusting the tension and / or the speed of supplying the web material (N1, N2), thereby ensuring that tension peaks (for example, tension peaks caused by uneven supply) are suppressed and the tension in the transverse direction of the web material is equalized. Figure 5 and 6 Example

[0070] Figure 5 and Figure 6 A second embodiment of a device 53 for adjusting and equalizing tension is shown. In this embodiment, a guide roller for guiding the web material is arranged along the path for supplying the web material, the guide roller being idlingly supported about a rotation axis. The guide roller is supported by a first pivot arm and a second pivot arm, capable of pivoting movement about the tension adjustment axis, and at least one first actuator is associated with it for controlling the tension adjustment movement of the pivot arm. The guide roller is supported so that a tension difference of the web material in a direction transverse to the direction of supplying the web material along the supply path causes a pivoting of the rotation axis of the guide roller to compensate for the tension difference.

[0071] To this end, the guide roller is idlingly supported on a support shaft, which is constrained to a first pivot arm and a second pivot arm. Advantageously, the first end of the support shaft is constrained to the first pivot arm by being hinged to a first rocker arm of the first arm, which first rocker arm pivots about a first hinge axis parallel to the axis for adjusting the tension. The second end of the support shaft is constrained to the second pivot arm by being hinged to a second rocker arm of the second arm, which second rocker arm pivots about a second hinge axis parallel to the axis for adjusting the tension. The first hinge axis and the second hinge axis are angularly staggered relative to each other around the axis of rotation of the guide roller, for example, they are arranged at 180° relative to each other.

[0072] Now, considering the attached figure, Figure 5 The device 53 for adjusting and balancing tension in this embodiment is shown. Figure 2 Similar cross-sectional views. The same numerals indicate the same Figures 2 to 4 The same or equivalent components described herein will not be described in detail below.

[0073] exist Figure 5 and Figure 6 In the embodiment of FIG. 5 , the guide roller 55 is supported on a shaft 173 by bearings 171A, 171B, the shaft being provided with a first end 173A and a second end 173B.

[0074] The first end 173A of the shaft 173 is keyed to a first rocker arm 175A, which is hinged to the first pivot arm 57A via a first hinge 177A. The axis of the hinge 177A is indicated by 179A. The axis 179A is parallel to the axis XX.

[0075] Likewise, the second end 173B of the shaft 173 is keyed to a second rocker arm 175B, which is hinged to the second pivot arm 57B via a second hinge 177B. The axis of the hinge 177B is indicated by 179B. The axis 179B is parallel to the axis XX.

[0076] The hinges 177A and 177B are realized by ball joints which make it possible to vary the inclination of the axis of the shaft 173 and the rockers 175A, 175B (kept orthogonal to each other) relative to the axes 179A, 179B of the hinges 177A, 177B.

[0077] like Figure 6 As shown, the hinge axes 179A, 179B are angularly staggered relative to the axis 55X. In the embodiment shown, the two axes 179A, 179B are staggered 180° around the axis 55X.

[0078] The two pivot arms 57A, 57B are mutually constrained by a torsion bar 157 which, for practical reasons, is coaxial with the pivot axis XX. In the embodiment shown, each pivot arm 57A, 57B is provided with an actuator 59A, 59B to achieve the above-mentioned purpose. The actuators 59A, 59B are functionally connected to the central control unit 100 in order to adjust the speed and / or tension of the web material (web N1 or web N2), for example, through a feedback loop which tends to keep the two pivot arms 57A, 57B and thus the guide roller 55 near a preset position.

[0079] When the tension on the web material is constant (i.e. uniform) in the transverse direction, the axis 55X of the guide roller 55 is arranged parallel to the adjustment axis XX. On the other hand, when a tension difference is generated between the right and left sides of the web material, i.e. in the transverse direction (parallel to the axis XX), said tension difference tends to pivot the first rocker arm 175A in a direction around the first hinge axis 177A and the second rocker arm 175B in the opposite direction around the second hinge axis 177B. Thus, the shaft 173 and the axis 55X of the guide roller 55 are tilted relative to a direction parallel to the axis XX. This tilting movement tends to equalize the tension in the transverse direction, i.e. it tends to reduce and eventually eliminate the tension difference on both sides of the web materials N1, N2. Figure 7 and 8 Example

[0080] Figure 7 and Figure 8 A further embodiment of a device 53 for adjusting and equalizing the tension of a continuous web of material is shown.

[0081] In this embodiment, a roller for guiding the web material is arranged along the path for supplying the web material, the roller being idly supported about a rotation axis and constrained to a first pivot arm and a second pivot arm, the first pivot arm and the second pivot arm being associated with at least one actuator, the at least one actuator controlling the movement of the first lateral support and the second lateral support for adjusting the tension. The guide roller is supported so that a tension difference of the web material in a direction transverse to the direction in which the web material is supplied along the supply path causes the rotation axis of the guide roller to pivot to compensate for the tension difference.

[0082] To this end, the guide roller is idlingly supported on a support shaft which is constrained to the first pivot arm and the second pivot arm. The support shaft is rigidly connected to the first pivot arm and the second pivot arm and forms a torsion bar connecting the first pivot arm and the second pivot arm.

[0083] Advantageously, the guide roller is idlingly supported on the support shaft by means of an intermediate bearing configured to allow the axis of rotation 55X to pivot relative to the support shaft about the center of the support bearing and to perform a tension equalization function.

[0084] Now, considering the attached figure, Figure 7 The device 53 for adjusting and balancing tension in this embodiment is shown. Figure 2 Similar cross-sectional views. The same numerals indicate the same Figures 2 to 4 Those components that are the same or equivalent to those described above will not be described again below.

[0085] exist Figure 7 and Figure 8In the embodiment of the invention, the guide roller 55 is supported on a shaft 173 coaxial with the guide roller 55. The shaft 173 has a first end 173A rigidly constrained to the first pivot arm 57A and a second end 173B rigidly constrained to the second pivot arm 57B. Thus, the shaft 173 acts as a torsion bar connecting the two pivot arms 57A, 57B.

[0086] The guide roller 55 is supported at a central position on the shaft 173 by a central bearing 181. The central bearing 181 is a spherical bearing that allows the guide roller 55 to pivot about the center of the bearing 181 to change the inclination of the axis 55X of the guide roller 55 relative to the axis of the shaft 173.

[0087] like Figure 7 and Fig. 9 As shown, when the tension of the web material guided around the guide roller 55 in the transverse direction is constant, the axis 55X of the guide roller 55 coincides with the axis of the shaft 173. The pivot arms 57A, 57B can control the tension and / or speed of the web materials N1, N2 via actuators 59A, 59B.

[0088] The ability of the guide roller 55 to pivot about the center of the bearing 181 enables tension equalization when an unbalanced condition occurs between the tension on the right and left sides of the web material guided around the guide roller 55, i.e., when the tension in the transverse direction is unbalanced. The tilted direction of the axis 55X tends to reduce and eventually eliminate tension differences along the width direction (i.e., the transverse direction) of the web material. Fig. 9 and 10 Example

[0089] Fig. 9 and Fig.10 A further embodiment of a device 53 for adjusting and equalizing the tension is shown.

[0090] In this embodiment, a roller for guiding the web material is arranged along the path for supplying the web material, the roller being idlingly supported around a rotation axis and constrained to a first pivot arm and a second pivot arm, the first pivot arm and the second pivot arm being associated with at least one actuator, which controls the movement of the first lateral support and the second lateral support for adjusting the tension.

[0091] The guide roller is supported such that a difference in tension of the web material in a direction transverse to the direction in which the web material is fed along the supply path causes the axis of rotation of the guide roller to pivot in order to compensate for said difference in tension.

[0092] To this end, the guide roller is idlingly supported on a support shaft which is constrained to the first pivot arm and the second pivot arm. Furthermore, the support shaft is connected to the first pivot arm and the second pivot arm via a ball joint and forms a torsion bar connecting the first pivot arm and the second pivot arm. Furthermore, it is advantageous if the support shaft is constrained at a first end to the first pivot arm and at a second end to the second pivot arm, thereby allowing mutual angular movement between the first pivot arm and the second pivot arm.

[0093] Now, considering the attached figure, Fig. 9 The device 53 for adjusting and balancing tension in this embodiment is shown. Figure 2 Similar cross-sectional views. The same numerals indicate the same Figures 2 to 4 The same or equivalent components described herein will not be described in detail below.

[0094] In this embodiment, the guide roller 55 is supported on the shaft 173 by bearings 191A, 191B in an idling manner.

[0095] The shaft 173 comprises a first end 173A constrained to the first pivot arm 57A and a second end 173B constrained to the second pivot arm 57B. The constraint between each end 173A, 173B and the corresponding pivot arm 57A, 57B is achieved by a ball joint 193A and 193B respectively. The ball joint allows the inclination of the axis of the shaft 173 relative to the pivot arms 57A, 57B to be changed.

[0096] At least one of the two pivoting arms 57A, 57B is constrained to the shaft 173 so as to be able to perform a mutual rotational movement about the axis 55X. In the embodiment shown, the two pivoting arms 57A, 57B can rotate relative to the shaft 173 by a limited angle.

[0097] To this end, the end 173A of the shaft 173 is provided with a first key 195A which is inserted into a seat 197A formed in a bushing 199A (see Fig.10 ) is integrally connected to the pivot arm 57A. Similarly, the end 173B of the shaft 173 is also provided with a second key 195B which is inserted into a seat 197B formed in the bushing 199B (see Fig.10 ), the bushing is integrally connected to the pivot arm 57B. The dimensions of the two seats 197A, 197B in the tangential direction are greater than the tangential dimensions of the corresponding keys 195A, 195B. This provides an angular clearance that allows relative rotation between the shaft 173 and each of the two pivot arms 57A, 57B.

[0098] In alternative embodiments, angular clearance relative to the axis 173 may be provided for only one of the pivot arms 57A, 57B.

[0099] In this arrangement, the synchronous pivoting of the pivot arms 57A, 57B under the control of the actuators 59A, 59B controls the tension and / or speed of the web material N1, N2, for example, by means of a control loop which tends to keep the axis of the guide roller 55 near a fixed position, absorbing changes in speed and / or tension, as in the above-described embodiments.

[0100] The tension differences in the transverse direction, ie the tension imbalance on the left and right sides of the web material N1 , N2 , are balanced and thereby equalized due to the subsequent pivoting of the shaft 173 relative to the angle of the two pivot arms 57A, 57B. Fig. 9 and Fig.10 The embodiments are basically the same as Figure 2 , Figure 3 and Figure 4 The embodiment of is similar, except that the torsion bar, relative to which the two pivot arms 57A, 57B can rotate limitedly, is arranged coaxially with the guide roller 55 instead of coaxially with the adjustment axis XX about which the pivot arms 57A and 57B pivot.

Claims

1. A device (53) for adjusting and equalizing the tension of a continuous web of material (N1, N2) supplied along a supply path; The device (53) comprises: a path for supplying web material (N1, N2); a guide roller (55) for guiding the web-like material (N1, N2), which is idlingly supported about a rotation axis (55X) and has a first axial end and a second axial end; a first lateral support (59A) and a second lateral support (59B) for guiding the roller (55); wherein the first lateral support (59A) and the second lateral support (59B) are movable to adjust the tension of the web material relative to the load-bearing structure (3) according to a tension adjustment axis (XX); at least one first actuator (59A; 59B) associated with the first lateral support (57A) and the second lateral support (57B) to control the movement of the first lateral support (59A) and the second lateral support (59B) for adjusting tension; The guide roller (55) is supported so that a tension difference of the web material in a direction transverse to the direction in which the web material (N1, N2) is supplied along the supply path causes a tilting of the rotation axis (55X) of the guide roller (55) to compensate for the tension difference.

2. The device (53) according to claim 1, wherein the tension adjustment axis (XX) is the pivot axis of the first lateral support (57A) and the second lateral support (57B) relative to the load-bearing structure (3); and wherein the first lateral support comprises a first arm pivoting around the tension adjustment axis (XX), and the second lateral support comprises a second arm pivoting around the tension adjustment axis (XX).

3. The device (53) according to claim 2, wherein the guide roller (55) is supported at a first axial end by a first pivot arm (57A) and at a second axial end by a second pivot arm (57B).

4. The device (53) according to claim 3, wherein the guide roller (55) is supported by a first pivot arm (57A) and a second pivot arm (57B) so that the rotation axis (55X) of the guide roller (55) can have a variable inclination relative to the first pivot arm (57A) and the second pivot arm (57B); and wherein the first pivot arm (57A) and the second pivot arm (57B) are constrained to each other by a torsion bar (157; 173) so as to be able to perform a relative angular displacement around the tension adjustment axis (XX), and the change in the inclination of the rotation axis (55X) of the guide roller (55) relative to the first pivot arm and the second pivot arm corresponds to the relative angular displacement.

5. A device (53) according to claim 4, wherein the torsion bar (157) is coaxial with the tension adjustment axis (XX); and wherein at least one of the first pivot arm (57A) and the second pivot arm (57B) is constrained to the torsion bar (157) so as to be able to perform angular movement around the tension adjustment axis (XX) relative to the other pivot arm.

6. The device (53) according to claim 5, wherein the at least one pivot arm is constrained to the torsion bar (157) by means of a key (161), the key allowing mutual angular movement between the torsion bar (157) and the at least one pivot arm (57B).

7. Device (53) according to one or more of claims 4 to 6, wherein the guide roller (55) is constrained to the first pivot arm (57A) by a first spherical bearing and to the second pivot arm by a second spherical bearing.

8. Device (53) according to one or more of claims 2 or 3, wherein the guide roller (55) is idlingly supported on a support shaft (173) constrained to the first pivot arm (57A) and the second pivot arm (57B).

9. The device (53) according to claim 8, wherein the first end (173A) of the support shaft (173) is constrained to the first pivot arm (57A) by a first rocker arm (175A), and the first rocker arm is hinged to the first pivot arm (57A) around a first hinge axis (179A) parallel to the tension adjustment axis (XX); the second end (173B) of the support shaft (173) is constrained to the second pivot arm (57B) by a second rocker arm (175B), and the second rocker arm is hinged to the second pivot arm (57B) around a second hinge axis (179B) parallel to the tension adjustment axis (XX); and wherein the first hinge axis and the second hinge axis are angularly offset relative to each other around the rotation axis (XX) of the guide roller (55).

10. The device (53) of claim 9, wherein the first hinge (177A) and the second hinge (177B) each comprise a respective ball joint to allow a respective rocker arm (175A, 175B) to have a variable inclination relative to an axis of the respective hinge (177A, 177B).

11. The device (53) of claim 9 or 10, wherein the first hinge axis (179A) and the second hinge axis (179B) are angularly offset by 180°.

12. The device (53) of claim 9 or 10 or 11, further comprising a torsion bar (157) connecting the first pivot arm (57A) to the second pivot arm (57B).

13. The device (53) according to claim 8, wherein the support shaft (173) is rigidly connected to the first pivot arm (57A) and the second pivot arm (57B), the support shaft (173) forming a torsion bar connecting the first pivot arm (57A) to the second pivot arm (57B).

14. The device (53) according to claim 13, wherein the guide roller (55) is idlingly supported on the support shaft (173) via an intermediate bearing (181) so as to be pivotable relative to the support shaft (173) about the center of the intermediate bearing.

15. The device (53) according to claim 8, wherein the support shaft (173) is idlingly mounted on the first pivot arm (57A) and the second pivot arm (57B) and forms a torsion bar connecting the first pivot arm and the second pivot arm.

16. A device (53) according to claim 15, wherein the support shaft (173) is constrained to the first pivot arm (57A) at a first end (173A) and to the second pivot arm (57B) at a second end (173B) to allow mutual angular movement between the first pivot arm (57A) and the second pivot arm (57B) about the tension adjustment axis (XX).

17. A device (53) according to claim 16, wherein at least one of the first end (173A) and the second end (173B) of the support shaft (173) is angularly constrained to the corresponding first pivot arm (57A) and the second pivot arm (57B) by a key (195A, 195B), and the key allows mutual angular movement between the first pivot arm (57A) and the second pivot arm (57B) about the tension adjustment axis (XX).

18. Device (53) according to one or more of the preceding claims, comprising a first actuator (59A) constrained to a first support (57A) and a second actuator (59B) constrained to a second support (57B).

19. The device (53) according to one or more of the preceding claims, comprising a position detector (167) for detecting the position of at least one of the first support (57A) and the second support (57B).

20. A device (53) for adjusting and equalizing the tension of a continuous web of material (N1, N2) supplied along a supply path; wherein the device (53) comprises: A roller (55) for guiding a web material (N1, N2), which is idlingly supported around a rotation axis (55X) by a first lateral support (57A) and a second lateral support (57B); wherein the first lateral support and the second lateral support are movable along an axis (XX) to adjust the tension of the web material (N1, N2); and wherein the guide roller (55), the first lateral support (57A) and the second lateral support (57B) are configured so that the rotation axis (55X) of the guide roller (55) is subjected to a force so as to change its inclination relative to the axis (XX) for adjusting the tension due to a change in the tension of the web material along a direction transverse to the advancing direction of the web material (N1, N2).

21. Apparatus according to claim 20, comprising one or more of the features of claims 2 to 19.

22. A single-sided machine (1), comprising: a first supply path (P1) for supplying a first paper web (N1); a second supply path (P2) for supplying a second paper web (N2); A first corrugating roller (9) and a second corrugating roller (11), which define a corrugating nip for a first paper web (N1) therebetween, and a first supply path (P1) passes through the corrugating nip; a pressure member (15) which, together with the first corrugating roller (9), defines a pressure nip through which the first supply path (P1) and the second supply path (P2) pass; At least one device (53) for adjusting and equalizing the tension of a paper web (N1, N2) according to one or more of the preceding claims, located on at least one of the first and second supply paths.

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