Single facer for the manufacture of corrugated board with a convenient system for replacing the extrusion belt

Abstract

The single facer (1) comprises a carrying frame (3) and a first and a second corrugating roller (15, 17) intermeshing and associated with the carrying frame (3). The single facer (1) further comprises a hinged structure hinged to the carrying frame (3) about a hinging axis (29) and comprising two hinged arms (23, 25) supporting two guide rollers (32, 35) of a continuous flexible member (31). Two actuators (41, 43) lift and lower the hinged arms and the guide rollers. A hinge system (23.2, 23.3) allows to keep the hinged structure in a cantilevered condition to replace the continuous flexible member (31).

Description

TECHNICAL FIELD

[0001] The present invention relates to a machine for manufacturing corrugated board. More specifically, the present invention relates to improvements to a corrugator or so-called "single facer". BACKGROUND

[0002] Corrugated board is manufactured starting from a smooth paper web unwound from a suitable reel. In its simplest form, corrugated board consists of a smooth paper web and a corrugated paper web glued together along the wave crests of the corrugated paper web. Usually, a second smooth paper web is required to be added on top of this basic structure, which is glued to the corrugated paper web so that the latter is interposed between the two smooth paper webs, also known as liners. In some cases, further structures having a series of corrugated paper webs interposed between smooth paper webs are added to this structure consisting of three paper webs.

[0003] Single facer corrugated board is produced by a "single facer" which comprises a pair of intermeshing corrugation rollers between which a first smooth paper web is fed. The first smooth paper web is hot deformed into the nip between the two corrugation rollers, which becomes a fluted paper web. An adhesive is applied on the fluted ridges of the fluted paper web glued to one of the corrugation rollers, and a smooth paper web is pressed and heated against the fluted paper web provided with adhesive.

[0004] A single facer is provided comprising an extrusion unit comprising at least one extrusion member pressed against one of the corrugation rollers for mutually gluing the fluted paper web and the smooth paper web. The smooth paper web and the fluted paper web pass between the corrugation rollers and the extrusion member.

[0005] In some single facers, the extrusion unit comprises a continuous flexible member in the form of a belt, which is driven around guide rollers. Single facers of this type are disclosed in US 9,545,769, EP 0 698 752, US 10,293,588, US 2015 / 0122423, US 5,512,020, EP 2 805 810, EP 2 792 477, US 5,951,817, US 2014 / 0345804, EP 0 850 753, JP 10-710, JP 2001-38830, JP 10-709.

[0006] US 2,638,962 discloses a corrugator comprising an extrusion belt driven around two guide rollers, wherein the first guide roller is rotatable around a fixed axis relative to a carrying structure, while the second guide roller is movable around a rotational movement of the fixed axis of the first guide roller. When the belt is moved away from the corrugation rollers, it is pressed against an outer cylinder which keeps the belt stretched.

[0007] JP11105172 discloses a corrugator with an extrusion belt driven around three rollers. A complex actuator system drives the movement of two belt guide rollers to control the traction of the belt and to maintain the correct guidance of the belt.

[0008] Another corrugator is disclosed in JP2962660, which has an extrusion belt and means for controlling the stretching and guiding of the belt. Also in this case, the belt is guided by a complex system consisting of three guide rollers and the relative actuators that control their movement.

[0009] EP3556548 discloses a single facer with a mechanism for replacing the corrugating rollers. The single facer also comprises a pair of fixed axis guide rollers around which the extrusion belt is driven. The extrusion belt is lifted when the corrugating rollers are removed from the single facer.

[0010] Continuous flexible members are complex, high-cost machine elements, given that they must withstand very high operating temperatures and operating tractions. They are subject to wear and tear and must be replaced periodically. The replacement causes the machine to stop. The replacement operation must be carried out with caution by trained personnel, so as not to damage the new continuous flexible member installed in the old position.

[0011] When manufacturing various types of corrugated paperboard, it is necessary to replace the corrugating rollers, due to the different shape and size of the flutes of the fluted web. In modern single facers, two corrugating rollers that intermesh are mounted in a roller cassette or drum, to simplify this operation. A plurality of roller cassettes or drums contain pairs of different corrugating rollers, for manufacturing different corrugated paperboards. The roller drum replacement is quick and simple. However, it can encounter obstacles in the presence of an extrusion unit. Replacing the corrugating rollers requires moving the corrugating rollers in the single facer away from the extrusion. This operation requires complex mechanical solutions. A single facer provided with a system of roller drums or cassettes for replacing the corrugating rollers is disclosed, for example, in US2007 / 0084565.

[0012] Furthermore, the use of continuous flexible members in the form of belts requires careful control of their traction and their position during operation. This requires the use of complex control and guidance systems.

[0013] Therefore, in this field, there is a constant search for simpler and more efficient constructive solutions, aimed at facilitating and simplifying one or more of the above-mentioned operations. SUMMARY

[0014] According to one aspect, there is provided a single facer for manufacturing single facer corrugated paperboard, comprising: a carrying frame; a first corrugation roller and a second corrugation roller, which are intermeshed and associated with the carrying frame; and a squeezing unit, which is pivoted to the carrying frame about a pivotal hinge, to be brought to a working position and a non-working position by means of rotation about a pivotal axis. The squeezing unit in turn comprises: a first pivotal arm; a second pivotal arm, which is rigidly connected to the first pivotal arm; a first guide roller, which has a first rotation axis, is supported on the first pivotal arm and on the second pivotal arm; a second guide roller, which has a second rotation axis, is supported on the first pivotal arm and on the second pivotal arm; a continuous flexible member, which is guided about the first guide roller and about the second guide roller. The first pivotal arm is suitable for supporting the second pivotal arm, the first guide roller and the second guide roller in a cantilevered manner on the carrying frame, to allow removal of the continuous flexible member from the side of the second pivotal arm.

[0015] More specifically, according to the embodiments disclosed herein, there is provided a single facer having a carrying frame and a pair of first and second corrugation rollers, which are intermeshed and mounted in the carrying frame. The single facer further comprises a squeezing unit for applying adhesive pressure between a smooth paper web and a fluted paper web. The squeezing unit comprises a pivotal structure, which is pivoted to the carrying frame about a pivotal axis. The pivotal structure comprises a first pivotal arm and a second pivotal arm, wherein the first pivotal arm is pivoted to the carrying frame by means of a first hinge system located on a first side of the single facer, while the second pivotal arm is located on a second side of the single facer. The two pivotal arms are rigidly connected to each other, for example by means of a crossbeam. The pivotal structure supports a first guide roller, whose first rotation axis is supported on the first pivotal arm and on the second pivotal arm, and a second guide roller, whose second rotation axis is also supported on the first pivotal arm and on the second pivotal arm. A continuous flexible member is guided about the first guide roller and about the second guide roller, between the two guide rollers.

[0016] Typically, the guide rollers have axes which are mutually substantially parallel and parallel to the pivotal axis about which the pivotal structure is pivoted with respect to the carrying frame. The pivotal axis in turn is substantially parallel to the axes of the corrugation rollers. The parallelism of the rotation axes of the guide rollers with respect to each other and with respect to the pivotal axis of the pivotal structure can not be exact, given that it is possible to vary the position of one or both of the rotation axes of the guide rollers to keep the continuous flexible member correctly guided and correctly stretched.

[0017] As will become clear in the following, it is particularly advantageous to space the pivotal axis of the pivotal structure from the first rotation axis of the first guide roller and from the second rotation axis of the second guide roller. In fact, this simplifies the structure of the single facer and allows easier replacement of the continuous flexible member. However, it cannot be excluded that the pivotal axis of the pivotal structure substantially coincides with the pivotal axis of one of the guide rollers.

[0018] The single facer further comprises a first actuator associated with the first articulated arm and forming a first constraint between the first articulated arm and the carrier frame, and a second actuator associated with the second articulated arm and forming a second constraint between the second articulated arm and the carrier frame. The first and second actuators alternately bring the articulated structure to the working position and to the raised position, in which the first and second guide rollers are spaced apart from the second corrugating roller.

[0019] In order to facilitate the removal of the worn continuous flexible member and the replacement with a new continuous flexible member, in an advantageous embodiment the first articulated arm forms a constraint with the first hinge system by which it is articulated to the carrier frame, wherein the carrier frame is adapted to support the second articulated arm and the first and second guide rollers mounted between the first and second articulated arms in a cantilevered manner, to allow the removal of the continuous flexible member from the second side of the single facer.

[0020] In principle, the second articulated arm can be constrained to the first articulated arm by means of a connecting crossbeam and further connected to the carrier frame by means of the second actuator, without having to be articulated to the carrier frame by means of a hinge device as well.

[0021] However, in the currently preferred embodiment, the second articulated arm is also articulated to the carrier frame and for this purpose a second hinge system can be provided. In this case, in order to allow the easy removal of the continuous flexible member to be replaced and the insertion of a new continuous flexible member, in an advantageous embodiment the second articulated arm is connected to the carrier frame by means of a removable element which is disassembled to remove the continuous flexible member from the first and second guide rollers. For example, such a removable element can comprise a removable bracket connecting the second articulated arm to the second hinge system.

[0022] In some embodiments, the first hinge system by means of which the first articulated arm is articulated to the carrier frame can comprise two hinges, spaced apart along the axis of articulation of the articulated structure, to provide resistance to the tipping torque generated by the weight of the first guide roller, the second guide roller and the second articulated arm when the second articulated arm is released from the carrier frame and held together with the two guide rollers in a cantilevered manner by the first articulated arm.

[0023] Further advantageous features and embodiments of the single facer are described hereinafter and defined in the appended claims, which are an integral part of the present description.

[0024] According to another aspect, a method is disclosed herein for operating a single facer as described above, wherein the step of replacing the continuous flexible member is as follows:

[0025] moving the first and second guide rollers away from the second corrugating roller;

[0026] releasing the second actuator from the second pivot arm and supporting the second pivot arm, the first guide roller and the second guide roller in cantilever fashion by means of the first pivot arm;

[0027] removing the continuous flexible member from the first guide roller and the second guide roller;

[0028] inserting a new continuous flexible member on the first guide roller and the second guide roller;

[0029] connecting the second actuator to the second pivot arm; and

[0030] lowering the pivot structure towards the second corrugating roller and pressing the continuous flexible member against the second corrugating roller.

[0031] Furthermore, the method can comprise the following steps:

[0032] releasing the second pivot arm from the second hinge system before removing the continuous flexible member from the first guide roller and the second guide roller, the second pivot arm being hinged to the carrier frame by means of the second hinge system;

[0033] connecting the second pivot arm to the second hinge system after inserting the new continuous flexible member on the first guide roller and the second guide roller.

[0034] According to another aspect, a single facer for manufacturing single facer corrugated paperboard is described herein, comprising a carrier frame, a first corrugating roller and a second corrugating roller which can be mounted in the carrier frame and which are intermeshing and mounted in the carrier frame. The single facer further comprises a pressing unit which is adapted to be pressed against the second corrugating roller. The pressing unit comprises a first guide roller which is pivotally supported about a first rotation axis and a second guide roller which is pivotally supported about a second rotation axis. A continuous flexible member is guided around the guide rollers.

[0035] characterized in that the first guide roller and the second guide roller are supported by a pivot structure which is pivoted to the carrier frame about a pivot axis which is substantially parallel to the axes of the first corrugating roller and the second corrugating roller. The pivot structure is associated with a control system which is adapted to rotate the pivot structure to a working position and to a raised position, wherein in the working position the continuous flexible member is pressed against the second corrugating roller and in the raised position the first guide roller and the second guide roller are spaced apart from the second corrugating roller.

[0036] The single facer can comprise other features described herein, in particular one or more of the features defined in the appended claims, in combination. BRIEF DESCRIPTION OF DRAWINGS

[0037] The invention will become more apparent from the description and the drawings, which illustrate embodiments by way of non-limiting example. More specifically, in the drawings: - Figure 1 shows a schematic view of a single facer according to the present invention; and - Figure 2 shows a schematic view of a single facer according to the present invention in a raised position.

[0038] Figure 1 shows a side view of the single facer in working position;

[0039] Figure 2 shows a side view of the single facer of Figure 1 from the opposite side relative to Figure 1 ;

[0040] Figure 2A shows a very simplified cross-sectional view of the single facer according to the intermediate vertical plane between the two sides;

[0041] Figure 2B shows a cross-sectional view of the single facer according to the intermediate vertical plane between the two sides in the position shown by Figure 1 and Figure 2 ;

[0042] Figure 3 shows a side view similar to Figure 1 , in which the pressing unit is raised;

[0043] Figure 4 shows a side view similar to Figure 2 , in which the pressing unit is raised;

[0044] Figure 5 shows a cross-sectional view of the single facer according to the intermediate vertical plane between the two sides of the single facer in the position shown by Figure 3 and Figure 4 ;

[0045] Figure 6 shows a view similar to Figure 3 , in which the roll box of the corrugating roller is removed;

[0046] Figure 7 shows a view similar to Figure 4 , in which the roll box of the corrugating roller is removed;

[0047] Figure 8 shows a cross-sectional view of the intermediate vertical plane of the single facer according to Figure 7 ;

[0048] Figure 9 shows an enlarged view of a detail of Figure 8 , in which some parts are removed;

[0049] Figure 10 shows a side view similar to Figure 6 , in which the pressing unit is lowered;

[0050] Figure 11 shows a side view similar to Figure 7Similar side view in which the extrusion unit is lowered;

[0051] Figure 12 A view similar to that of Figure 11 , in which the actuator of the extrusion unit is in the disengaged condition from the respective articulated arm;

[0052] Figure 13 A perspective view of the single-faced corrugator in Figure 12 position, in which the continuous flexible member is partially extracted from the guide rollers;

[0053] Figure 14 A view of the single-faced corrugator according to Figure 12 , according to the line XIV-XIV;

[0054] Figure 15 and 16 A view similar to that of Figure 14 , in which the details indicated with XV and XVI are shown enlarged;

[0055] Figure 17 A top view of the extrusion unit;

[0056] Figure 18 A view according to Figure 17 , according to the line XVIII-XVII;

[0057] Figure 19 A view according to Figure 17 , according to the line XIX-XIX;

[0058] Figure 20 A sectional view according to Figure 17 , according to the line XX-XX;

[0059] Figure 21 A sectional view according to Figure 19 , according to the line XXI-XXI;

[0060] Figure 22 A sectional view according to Figure 19 , according to the line XXII-XXII;

[0061] Figure 23 A partial perspective view of the extrusion unit on the side in which the motor actuating the continuous flexible member is installed;

[0062] Figure 24A and 24B A partial perspective view of the extrusion unit 21, showing the sensor for detecting the position of the continuous flexible member 31;

[0063] Figure 25A , 25Btwo schematic side views of the extrusion unit are shown, illustrating the movement of one of the two guide rollers of the continuous flexible member to adjust its stretch;

[0064] Figure 26 and Figure 27 two schematic views of the extrusion unit are shown, illustrating the movement of one of the guide rollers of the continuous flexible member to correct its twist; and

[0065] Figure 28A 、 28B two schematic views of the extrusion unit are shown, illustrating the movement of one of the two guide rollers of the continuous flexible member to correct its twist. DETAILED DESCRIPTION

[0066] The general structure of the single facer 1 can be understood with reference to Figure 1 、 2 and 2A, where the first two figures show side views of the single facer seen from two opposite sides, while Figure 2A shows a very simplified cross-sectional view according to an intermediate vertical plane between the two sides, where only the main components of the single facer 1 are shown. Figure 2B shows a cross-sectional view according to an intermediate vertical plane between the two sides of the single facer.

[0067] The single facer 1 comprises a carrying frame 3 on which the corrugating rollers are supported, and an extrusion unit for pressing two paper webs forming a single facer paperboard (not shown in the figures) against each other. The carrying frame comprises a first side wall 5 on a first side of the single facer 1 and a second side wall 7 on a second side of the single facer 1, see also Figure 14 and 17 . The two side walls 5 and 7 are joined to each other by cross beams 9, 11, as shown in particular in Figure 13 and 14 , where the corrugating rollers of the single facer 1 have been removed. Typically, the first side is the drive side, i.e. the side where the drive means are located, while the second side is the operator side, i.e. the side where the operator can typically access the single facer 1.

[0068] A roller box or cylinder 13 comprising a first corrugating roller 15 and a second corrugating roller 17 stacked on the first corrugating roller is inserted into the carrying frame 3. The roller cylinder 13 is replaceable, i.e. interchangeable, to change the properties of the corrugated web produced by the single facer 1 using different corrugating rollers 15, 17.

[0069] The roller box 13 is supported within the load-bearing frame 3 of the single-face corrugating machine 1 by means of two forming support profiles 13.1 and 13.2, which work in conjunction with complementary support profiles 3.1 and 3.2, which are integrally integrated with the load-bearing frame 3. The roller box is inserted into the single-face corrugating machine 1 on the side of the single-face corrugating machine 3 (typically on the side defined by the second sidewall 7). Insertion on opposite sides or both sides cannot be ruled out.

[0070] Advantageously, the roller box 13 is inserted into the support frame 3 and supported on the support profiles 3.1, 3.2, wherein the roller box 13 remains stationary due to the weight of the roller box and the corrugated rollers 15, 17 and due to the thrust of the extrusion unit, which will also be described below.

[0071] Corrugated rolls 15 and 17 are known in themselves and will not be described in detail. Each of them has a corrugated cylindrical surface, and the two grooved cylindrical surfaces mesh with each other at the corrugated roll gap defined between the two corrugated rolls 15 and 17, through which the first smooth paper web passes and is corrugated due to the pressure applied by the two corrugated rolls.

[0072] The first corrugated roller 15 and only in Figure 2A The adhesive applicator 16 shown in the simplified cross-section works together, and the adhesive applicator 16 applies adhesive to the grooved ridges formed on the first paper web before applying adhesive to the second smooth paper web (while still adhering to the second corrugated roll 17). In order to bond the two paper webs, one grooved and one smooth, the single-facer 1 includes an extrusion unit or assembly 21 arranged to act from top to bottom on the upper part of the two paper webs around the second corrugated roll 17 that guides them.

[0073] The extrusion unit or assembly 21 includes a pivot structure, which in turn includes a first pivot arm 23 located on a first side of the support frame 3 and a second pivot arm 25 located on a second side of the support frame 3. The two pivot arms 23, 25 can be rigidly connected to each other, for example, by means of a crossbeam 27. In the illustrated embodiment, the two pivot arms 23, 25 are hinged to the support frame 3 about a pivot axis 29, which is parallel to the axis of the corrugated rollers 15, 17 when the corrugated rollers 15, 17 are installed in the single-face corrugator 1.

[0074] The extrusion unit or assembly 21 also includes a continuous flexible member 31, such as a continuous strip. The continuous flexible member 31 is guided about a first guide roller 32, thereby rotating about a first rotation axis 33, and about a second guide roller 35, thereby rotating about a second rotation axis 37. The guide rollers 32, 35 and the corresponding rotation axes 33, 37, and the continuous flexible member 21 are specifically shown in… Figure 5 and Figure 8 In the cross-sectional view.

[0075] The overall operation of the single facer is easily understood with reference to the simplified section of Fig. 1. Figure 2A A first smooth paper web N1 is guided around the heated roll 20 and is fed into the corrugating nip between the first and second corrugating rolls 15, 17, where it is permanently deformed, forming flutes parallel to the rotation axis of the corrugating rolls 15, 17. The first paper web N1 remains adhered to the second corrugating roll 17 and receives the adhesive applied by the adhesive applicator 16 on the flutes thus formed. Downstream of the adhesive applicator 16, the first corrugated web N1 is guided by the second corrugating roll 17 under the extrusion unit 21 and more precisely between the corrugated surface of the second corrugating roll 17 and the continuous flexible member 31 acting on the second corrugating roll 17. A second smooth paper web N2 is guided around the heated roll 22 and is fed between the first fluted paper web N1 adhered to the second corrugating roll 17 and the extrusion unit 21 and more precisely under the continuous flexible member 31 of the extrusion unit 21. The pressure exerted on the two webs N1, N2 in the nip between the extrusion unit 21 and the second corrugating roll 17 causes the webs N1, N2 to adhere to each other. At the outlet of the single facer 1, a single facer paperboard web SF is obtained, the structure of which can be seen in the enlarged view of Fig. 2. The adhesive bonding the fluted web N1 to the smooth web N2 is denoted by C. Figure 2A

[0076] The first and second guide rolls 32, 35 define a first branch of the continuous flexible member 31 comprising the portion of the continuous flexible member 31 facing the second corrugating roll 17 between the two guide rolls 32, 35. The first branch of the continuous flexible member 31 constitutes the active branch, i.e. the branch that is pressed against the second corrugating roll 17. A second branch or return branch of the continuous flexible member 31 is defined between the guide rolls 32, 35 on the opposite side, i.e. opposite the second corrugating roll 17.

[0077] The gear motor 39 providing the rotational movement to the second guide roll 35 and thus to the continuous flexible member 31 is mounted on the first articulated arm 5, while the first guide roll 32 is mounted idly on the articulated arms 23, 25.

[0078] In other embodiments not shown, no gear motor 39 is provided and both guide rolls 32 and 35 are mounted idly on a pivoting structure. In this case, the movement of the continuous flexible member can be provided by friction of the second corrugating roll 17.

[0079] ​The first pivotal arm 23 is constrained to a first linear actuator 41, for example a cylinder-piston actuator, preferably of the hydraulic type. One end 41.1 of the linear actuator 41 is pivoted to the load frame 3, while the second end 41.2 of the linear actuator 41 is pivoted to the first pivotal arm 25. Opposite the single facer 1 is a second linear actuator 43 which constrains the second pivotal arm 25 to the load frame 3. One end 43.1 of the linear actuator 43 is pivoted to the load frame 3, while the second end 43.2 of the linear actuator 43 is pivoted to the second pivotal arm 25. The two linear actuators 41, 43 control the pivotal movement of the pivoting structure comprising the pivotal arms 23, 25 and the crosspiece 27 about the pivotal axis 29 to perform the operations which will be described hereinafter.

[0080] Further details of the pressing unit 21 will be described hereinafter. In particular, the following aspects will be described: details regarding the mutual connection between the pivotal arms 23, 25 and the load frame 3 and the system for facilitating the replacement of the continuous flexible member 31; details regarding the system for facilitating the replacement of the roll box or roll cylinder; and details regarding the system for controlling the traction force and keeping the continuous flexible member 31 guided. As will be clear from the present description, the combination of features regarding these three functions of the single facer 1 is in the illustrated embodiment. However, they can be used separately from each other. For example, the features for facilitating the replacement of the corrugation rolls can be used in a single facer 1 having a different system for replacing the continuous flexible member and / or a different system for controlling the traction force and keeping the continuous flexible member guided. Similarly, the features and elements for facilitating the replacement of the continuous flexible member can be used with a different system for facilitating the replacement of the corrugation rolls and / or a different system for controlling the traction force and keeping the continuous flexible member guided. Similarly, the latter can also be used with a single facer having a different system for changing the corrugation rolls and / or a different system for replacing the continuous flexible member.

[0081] Before describing the aforementioned aspects in more detail, reference is made here to Figures 1 to 7 Described is the movement performed by the single facer 1, more precisely by the pressing assembly or unit 21, for removing the roll box 13 of the corrugation rolls 15, 17. Figure 1 and 2 A side view of the first and second side of the single facer 1 with the roll box or roll cylinder 13 and the respective corrugation rolls 15, 17 is shown. The pressing unit 21 is in the working position, i.e. in the lower position. In this position, the continuous flexible member 31 is pressed against the upper part of the second corrugation roll 17, i.e. arranged at the higher level of the corrugation roll resting in the roll box 13 resting on the load frame 3. In this working position, the actuators 41, 43 push the pressing unit 21 downwards. In the illustrated embodiment, each pivotal arm 23, 25 has a support 23A and 25A. The two supports 23A, 25A are arranged to cooperate with the support 13A carried by the roll cylinder 13. The supports 23A, 25A in particular have a recess 23B and 25B, respectively, which are arranged to receive the support 13A of the roll cylinder 13.Figure 2 , 4 , 5, 7. One of the supports 13A is visible in particular in Figure 2 .

[0082] When the single facer 1 is in the working position, the articulated arms 23, 25 assume an angular position defined by the resting of the supports 23A, 25A on the supports 13A of the roller boxes 13, which in turn rest on the support profiles 3.1, 3.2. The pressure exerted by the actuators 41, 43 keeps the articulated arms 23, 25 in position and helps to keep the roller boxes 13 of the corrugating rollers 15, 17 in the correct position.

[0083] A stretching actuator, as described below, exerts a traction force on the continuous flexible member 31 when the pressing unit 21 is in the working position, so as to keep the continuous flexible member 31 adhering to the web of paper (not shown) interposed between the continuous flexible member 31 and the second corrugating roller 17. The traction force of the continuous flexible member reduces the thrust exerted by the actuators 41, 43 on the supports 13A.

[0084] In order to replace the roller boxes 13, the pressing unit 21 is first rotated upwards with a rotational movement about the articulation axis 29. With this movement, the pressing unit 21 is brought to a raised position, spaced apart from the roller boxes 13. The lower branch of the continuous flexible member 31, i.e. the branch facing the second corrugating roller 17, is kept under traction between the first guide roller 32 and the second guide roller 35 by means of a mechanism which will be described below.

[0085] The raised position of the pressing unit 21, and therefore of the articulation structure and of the guide rollers 32, 35 carried thereby, is represented in the two side views of Figure 3 (first face of the single facer 1) and 4 (second face of the single facer 1), as well as in the cross-sectional view of Figure 5 .

[0086] The arrangement of the articulation axis 29 of the articulation structure at a distance from both the rotation axes 33, 37 of the first guide roller 32 and of the second guide roller 35 allows a greater spacing to be obtained between the guide rollers and the second corrugating roller 17, thus facilitating the removal of the roller boxes 13.

[0087] The provision of the pressing unit 21 with a lifting and lowering movement about the articulation axis 29 makes it possible to obtain an extremely simple and reliable system for performing the various operations required by the single facer, in particular: keeping the continuous flexible member 31 under the pressure of the second corrugating roller 17 during the production of corrugated cardboard; the operation of replacing the roller boxes 13; the operation of replacing the continuous flexible member 31.

[0088] When the articulated structure is in the raised position, the roller box 13 can be lifted from the support profiles 3.1 and 3.2 and can be removed from the single facer 1. In the illustrated embodiment, the roller box 13 can preferably be removed by taking it out from the second side of the single facer 1, but the possibility of removing it from the first side of the single facer 1 cannot be excluded. Figure 6 、 7 and 8 show a side view and a cross-sectional view of the single facer 1 after removal of the roller box 13.

[0089] After removal of the roller box 13, it can be replaced with a roller box 13 having different corrugating rollers 15, 17, so as to manufacture another type of corrugated paperboard.

[0090] As clearly shown in Figure 1 、 Figure 2 and Figure 3 , when the articulated structure, comprising the first articulated arm 23, the second arm 25 and the crosspiece 27, is moved away from the second corrugating roller 17, the continuous flexible member 31 tends to slacken and its first branch, facing the second corrugating roller 17, tends to rest on the second corrugating roller 17. Upon removal of the roller box 13, the first branch (lower branch) of the continuous flexible member 31 will hang down, at least partially occupying the space in which the new roller box 13 is to be inserted. This can damage the continuous flexible member 31 if the operator who inserts the new roller box 13 does not pay sufficient attention and does not take care to manually lift the first branch of the continuous flexible member 31.

[0091] In view of its design for withstanding extreme working conditions, both in terms of traction and in terms of working temperature, the continuous flexible member 31 is a very expensive machine element. In fact, the corrugating rollers are heated to accelerate the mutual adhesion between the paper webs forming the corrugated paperboard, and the continuous flexible member 31 is subjected to very high traction, thus generating very high pressure on the second corrugating roller 17, again accelerating the adhesion of the paper webs forming the corrugated paperboard.

[0092] In the illustrated embodiment, in order to avoid the risk of damaging the continuous flexible member 31 during replacement of the roller box 13, the extrusion unit or assembly 21 comprises stretching means, indicated as a whole with the reference numeral 51 and visible in particular in Figure 8 and 9 .

[0093] In the illustrated embodiment, the stretching device 51 includes a stretching rod 53 arranged in a closed path defined by the continuous flexible member 31. The stretching rod 53 extends generally parallel to the pivot axis 29 and is carried by the pivot structure. Therefore, the stretching rod participates in the pivotal movement of the pivot structure about the pivot axis 29. When the extrusion unit 21 is in the working position, the stretching rod 53 is in the non-working position, preferably not in contact with the continuous flexible member 31, or in any case not subject to any considerable force. For this purpose, the stretching rod 53 can be accommodated in the space between the first guide roller 32 and the second guide roller 35.

[0094] When the pivot structure moves from the working position ( Figure 1 , 2 Raise to the lifted position ( Figure 3 , 4 At time 5), the tension rod 53 is raised together with the pivot structure, and at the same time it performs a movement relative to the first guide roller 32 and the second guide roller 35, thereby pushing the second branch of the continuous flexible member 31 from the inside, which faces the opposite side of the second corrugated roller 17. Figure 8 and 9 The final position occupied by the tension rod 53 is shown once the pivot structure is brought to its fully raised position. The tension rod 53 of the tensioning device 51 pushes the return branch of the continuous flexible member 31 outward, deforming it and preventing the flexible member from loosening toward the first branch of the second corrugated roller 17. Essentially, the first branch of the continuous flexible member 31 remains stretched between the first guide roller 32 and the second guide roller 35. The traction force applied to the continuous flexible member 31 is negligible. It is sufficient to prevent the first branch of the continuous flexible member 31 from slackening downward.

[0095] In some embodiments not shown, the movement of the tension rod can be driven by an actuator carried by a pivot structure including pivot arms 23, 25 and beam 27. However, for safer operation and to simplify the structure and thus reduce costs, it is advantageous to provide a tensioning device 51 that is passively activated when the pivot structure is brought to the raised position.

[0096] For this purpose, the tension rod 53 is supported by a mechanism that works together with the static elements constrained to the load-bearing frame 3, and this cooperation causes the tension rod 53 to move relative to the pivot structures 23, 25, 27.

[0097] In the illustrated embodiment, the tension rod 53 is carried by two pivot levers 55, each pivot lever being associated with a corresponding pivot arm 23, 25. The two pivot levers 55 (in...) Figure 8 and Figure 9around a hinge axis 57 integral with the articulated arms 23, 25 and substantially parallel to the hinge axis 29. Each articulated lever 55 has a first end 55.1 constrained to the stretching rod 53 and a second end 55.2 arranged in the vicinity of the second guide roller 35. The second end of each articulated lever 55 forms a mobile abutment which cooperates with a respective abutment 59 mounted on the carrying frame 3. Each abutment 59 can be fixed or almost fixed, for example it can be an elastic abutment for damping the impact of the end 55.2 of the articulated lever 55. An elastic member 59.1, for example a pneumatic spring, can gradually contract when the articulated arms 23, 25 reach the maximum raised position. The contraction of the elastic member 59.1 allows the respective abutment 59 to articulate upwards under the thrust of the end 55.2 of the respective articulated lever 55, while the latter's hinge point (axis 57) moves following the lifting of the articulated structure 23, 25, 27 (see Figure 9 ). The elasticity provided by each of the two elastic members 59.1 allows to compensate for any stretching or contraction of the continuous flexible member 31, ensuring that it is always sufficiently stretched by the stretching rod 53.

[0098] As shown in Figure 9 , when the articulated structure, comprising the articulated arms 23, 25 and the crosspiece 27, on which the stretching rod 53 is rotatably supported, is lifted until it reaches the position of maximum distance from the second corrugating roller 27, the stretching rod rotates around the axis 57 due to the cooperation of the end 55.2 of the articulated lever 55 with the abutment 59. Therefore, the stretching rod 53 pushes the second branch of the continuous flexible member 31, stretching the first branch of the continuous flexible member, preventing it from tending to relax downwards into the area of the roller box 13 of the moving corrugating rollers 15, 17. Basically, as shown in Figure 5 and 8 , when the articulated structure is in the raised position, the continuous flexible member 31 is stretched between the two guide rollers 32, 35 and the stretching rod 53. This makes the roller box 13 easier to move and without the risk of damaging the continuous flexible member 31.

[0099] In some embodiments, the single facer 1 can comprise means to facilitate the replacement of the continuous flexible member 31. In fact, this member is subject to wear due to the high thermal and mechanical stresses to which it is subjected.

[0100] To facilitate the replacement of the continuous flexible member 31, the articulated structure comprising the articulated arms 23, 25 and the crosspiece 27 is constrained to the load-bearing frame 3 so as to be able to support the guide rollers 32, 35 in a cantilevered manner on one of the two articulated arms and to allow the removal of the continuous flexible member 31 from the side of the other articulated arm. In the example shown, as will be described in greater detail below, the first articulated arm 23 is constrained to the load-bearing frame 3 so as to be able to support the first guide roller 32, the second guide roller 35 and the second articulated arm 25 in a cantilevered manner (which can be temporarily detached from the load-bearing frame 3 to allow the removal and replacement of the continuous flexible member 31 from the side of the second articulated arm 25).

[0101] With particular reference to the figures as Figure 13 , 14 and 23, the first articulated arm 23 comprises a crosspiece 23.3 rigidly connected to the articulated arm 23 and extending in a cantilevered manner substantially parallel to the articulation axis 29. The articulated arm 23 with the respective crosspiece 23.1 defines two hinges 23.2 and 23.3 (see in particular Figure 23 ), which are coaxial with each other and spaced apart in the direction of the articulation axis 29. The two hinges 23.2 and 23.3 form, on the side of the side wall 5, elements for constraining the articulated arm 23 to the load-bearing frame 3.

[0102] The two hinges 23.2, 23.3 spaced apart from each other provide a constraint to the first articulated arm 23. The arm 25 is also held in a cantilevered manner by means of the crosspiece 27, which connects the articulated arms 23, 25 to each other. Finally, the guide rollers 32, 35 as well as the articulated arms 23, 25 are supported by the hinge system 23.2, 23.3, which connects the articulated arm 23 to the load-bearing frame 3. In this way, the articulated arm 25 can be detached from the load-bearing frame 3, thus allowing the easy replacement of the continuous flexible member 31 as will be described below.

[0103] In the example shown, the second articulated arm 25 is constrained and articulated to the load-bearing frame 3 by means of a hinge 25.1, as shown in particular in Figure 14 . The second articulated arm 25 is provided with a removable bracket 25.2 that connects the articulated arm 25 to the hinge 25.1, as can be seen in particular in the side view of the second side of the single facer 1 (see Figure 2 , 4 , 7, 11, 12). The function of the bracket 25.2 will be clarified with reference to the sequence of operations for removing a worn continuous flexible member 31. These operations are described in detail in Figure 7 , 8 and 10 to 13.

[0104] Figure 7 and 8The diagram shows the initial operations required for clearing space for replacing the continuous flexible member 31 in a single-sided corrugating machine 1 from which the roller box 13 has been removed.

[0105] from Figure 7 , 8 From the perspective of position, the pivot structure, including the pivot arms 23, 25 and the crossbeam 27 with two guide rollers 32, 35, is lowered by rotating around the pivot axis 29 until it reaches a position below the normal working position, that is, below the position where the supports 23A, 25A of the pivot arms 23, 25 rest on the support 13A of the roller box 13 in the single-face corrugating machine 1.

[0106] The position of the pivot structure after its descent is at Figure 10 Shown on the side of sidewall 5, while Figure 11 and Figure 12 The side shown is away from sidewall 7. The position of the pivot structure in this operation step is defined by fixed support 61 and movable support 63. Fixed support 61 is integrated with the load-bearing frame 3, more precisely, with the first sidewall 5 of the load-bearing frame 3. Movable support 63 is integrated with the first pivot arm 23. During the step of replacing the continuous flexible member 31, supports 61, 63 allow for defining a lower position of the pivot structure and give the pivot arm 23 greater stability.

[0107] At the lower part of the pivot structure, such as Figure 10 , 11 As shown in Figures 1 and 12, the continuous flexible member 31 is no longer held in tension by the tension rod 53, and its first branch is loosely suspended in the space left by the roller box 13 with corrugated rollers 15 and 17.

[0108] Upon reaching this position, in order to remove the continuous flexible member 31, the second pivot arm 25 first separates from the side wall 7 of the supporting frame 3. For this purpose, as... Figure 11 and 12 As shown, the bracket 25.2 separates from the rest of the arm 25 and rotates downward about the pivot axis 29. Furthermore, as... Figure 11 and 12 As shown, actuator 43 is separated from arm 25.

[0109] In some embodiments not shown, the pivot arm 25 may be pivotally connected to the support frame 3 without the aid of its hinge. In this case, the bracket 25.2 is not provided, and the pivot arm 25 is disengaged from the support frame 3 more quickly, as it only requires separating the actuator 43.

[0110] exist Figure 12In this position, the arm 25 is substantially separated from the carrying frame 3. It is held in cantilever fashion by the crosspiece 27 constrained to the articulated arm 23. This is constrained to the carrying frame 3 by means of the two hinges 23.2, 23.3, the actuator 41 and the rest 63 resting on the support 61.

[0111] Therefore, as shown in the isometric view of Figure 13 , the continuous flexible member 31 can be removed from the guide rollers 32, 35. Once the worn continuous flexible element 31 has been removed, it can be replaced with a new continuous flexible element 31. The guide rollers 32, 35, the continuous flexible member 31 and the articulated arms 23, 25 are returned to the raised position of Figure 6 , 7 , 8 by means of operations opposite to those described above.

[0112] In this position, the new continuous flexible member 31 is held taut by the stretching rod 53 so that the first branch of the continuous flexible member 31 assumes a straight shape and frees the space below in which the first corrugating roller 15 and the second corrugating roller 17 are inserted in the roller box body 13 Figure 3 , 4 and Figure 5 . Subsequently, the extrusion unit comprising the continuous flexible member 31, the guide rollers 32, 35, the articulated arms 23, 25 and the crosspiece 27 is lowered to the working position Figure 1 and Figure 2 .

[0113] When the single facer 1 is in the working position, the continuous flexible member 31 must be kept correctly stretched and guided around the guide rollers 32, 35. The width of the continuous flexible member 31 and the axial length of the guide rollers 32, 35 are very large with respect to the length of the continuous flexible element. This makes the guiding of the continuous flexible member 31 particularly critical. In order to keep the continuous flexible member 31 correctly stretched and guided, the adjustment and guiding arrangement of the continuous flexible member 31 described below with specific reference to Figures 14 to 23 is provided. This system serves to maintain the correct stretching of the continuous flexible member 31, to prevent or correct any slippage in the transverse direction, i.e. displacement along the axis of the guide rollers 32, 35, and to avoid or correct twisting of the continuous flexible member 31. Twisting occurs when the two edges of the continuous flexible member 31 do not advance uniformly, so that the line of the continuous flexible member 31 originally parallel to the axis of rotation of the guide rollers 32, 35 is displaced so that it is no longer parallel to such an axis of rotation.

[0114] In the illustrated embodiment, the articulated arms 23, 25 are associated with respective actuators which independently adjust the distance between the rotation axes of the two guide rollers 32, 35 on both sides of the single-faced corrugator 1. Furthermore, on one of the two sides of the single-faced corrugator 1, a further actuator is provided which is associated with one end of one of the two guide rollers 32, 35 and adjusts the inclination of the axis of said guide roller in the transverse direction, preferably substantially orthogonal to the direction of adjustment of the centre distance of said guide roller.

[0115] More specifically, the first guide roller 32 is supported on the first articulated arm 23 by means of a first support 32.1 and on the second articulated arm 25 by means of a second support 32.2. Similarly, the second guide roller 35 is supported to the first articulated arm 23 by means of a first support 35.1 and to the second articulated arm 25 by means of a second support 35.2.

[0116] In the illustrated embodiment, as will be detailed hereinafter, the supports 35.1 and 35.2 of the second guide roller 35 are mounted in fixed position with respect to the first articulated arm 23 and the second articulated arm 25, while the supports 32.1 and 32.2 of the first guide roller 32 are mounted so as to enable them to move in a controlled manner with respect to the first articulated arm 23 and the second articulated arm 25.

[0117] In the illustrated embodiment, the first support 32.1 of the first guide roller 32 and the second support 32.2 of the first guide roller are mounted in respective mobile units, one of which is indicated in detail in cross-section in the figure with the reference 71. The supports 32.1 and 32.2 are articulated supports, i.e. they allow the inclination of the rotation axis 33 of the first guide roller 32 to be changed in such a way as to achieve the following purposes. Figure 20

[0118] The mobile unit 71 contains the first support 32.1 of the first guide roller 32 and connects it to the first articulated arm 23 as will be described hereinafter. For the analogous mobile unit 72, the second support 32.2 of the first guide roller 32 is mounted in the same way on the second articulated arm 25, with reference to Figure 17 , 18 , 19 and 20.

[0119] With particular reference to Figure 20 , the mobile unit 71 has a seat 71.1 for the first support 32.1 of the first guide roller 32. The mobile unit 71 is constrained to the articulated arm 23 by means of a rocker 73, one end of which is articulated to the mobile unit 71 and the other end is articulated to the articulated arm 23. The axes for the articulation of the rocker 73 to the arm 23 and to the mobile unit 71 are indicated with the references 73.1 and 73.2, respectively.

[0120] ​The mobile unit 71 is further constrained to the articulated arm 23 by means of a first actuator 75, which is used to adjust the traction of the continuous flexible member 31. In the illustrated embodiment, the first actuator 75 is a linear actuator, for example a cylinder-piston actuator, preferably of the double-acting hydraulic type.

[0121] In the illustrated embodiment, the actuator 75 comprises a cylinder 75.1 formed in the mobile unit 71, inside which a piston 75.2 slides. In turn, the rod of the piston 75.2 is articulated in 75.3 to the first articulated arm 23. The movement of the actuator 75 causes the pivoting of the rocker arm 73 and the following movement of the rotation axis 33 of the first guide roller 32 with respect to the articulated arm 23.

[0122] An analogous arrangement is provided for connecting the second support 32.2 of the first guide roller 32 to the second articulated arm 25.

[0123] The action on the two actuators 75 associated with the two supports 32.1 and 32.2 allows to vary the traction of the continuous flexible member 31, due to the variation of the distance between the rotation axes 33 and 37 of the two guide rollers 32, 35.

[0124] The two actuators 75 on the two sides of the single facer 1 can be actuated independently of each other, in the sense that they allow to adjust independently the position of the respective supports 32.1 and 32.2 of the first guide roller 32 with respect to the respective supports 35.1 and 35.2 of the second guide roller 35. This allows to keep the continuous flexible member 31 properly guided and properly stretched. The independent actuation of the actuators 75 allows to vary the inclination of the rotation axis 33 of the first guide roller 32, so that it is not completely parallel to the rotation axis 37 of the second guide roller 35. This variation of inclination can be used, for example, to compensate or correct the twisting of the continuous flexible member 31.

[0125] The actuators 75 can be controlled by a control unit (not shown) on the basis of signals coming from sensors (not shown) provided on the single facer 1. For example, a load cell can be provided for detecting the traction of the continuous flexible member 31, which corresponds to the determined pressure on the second corrugating roller 17, and therefore to the determined adhesion pressure between the smooth web and the fluted web. In addition, sensors can be provided which read the position of one or both longitudinal edges of the continuous flexible member 31. Alternatively, the traction can be determined simply on the basis of the pressure of the hydraulic fluid used to control the actuators 75.

[0126] More specifically, based on the signals of these sensors, possible displacements of the continuous flexible member 31 can be corrected by differential action on the two actuators 75, thus causing a variation in the inclination of the rotation axis 33 of the first guide roller 32. Since the two actuators 75 are simultaneously acted upon, the rotation axis 33 is caused to translate parallel to itself by imparting identical movements thereon, thus varying the traction of the continuous flexible member 31.

[0127] In the illustrated embodiment, the pivot axis 73.1 of the rocker 73 associated with the articulated arm 25 is fixed (see Figure 18 ). On the other hand, the pivot axis 73.1 of the rocker 73 associated with the articulated arm 23 is mobile, to impart a further adjustment movement to the first guide roller 32. This further movement will be more apparent with reference to 19, 20 and 21. The pivot axis 73.1 of the rocker 73 associated with the first articulated arm 23 comprises an eccentric 73.3 housed in a base 73.4 of the articulated arm 23 (see Figure 20 ). The eccentric 73.3 rotates in the base 73.4 about an axis 73.5 parallel to, but spaced from, the pivot axis 73.1 of the rocker 73. In the illustrated embodiment, the rotation of the eccentric 73.3 is controlled by means of a linear actuator 77, for example an electric jack, by means of a lever 79 (see Figure 19 ).

[0128] The rotation of the eccentric 73.3 about the axis 73.5 causes a displacement of the pivot axis 73.1 of the rocker 73 with respect to the articulated arm 23. In Figure 20 , the general direction of this displacement is indicated with the reference f73. This direction is transversal to the direction of displacement imparted by the linear actuator 75, indicated with the reference f75. In this way, on the side of the first articulated arm 23, the first support 32.1 of the first guide roller 32 is able to be displaced according to two directions substantially orthogonal to each other. The displacement according to the arrow f75 Figure 20 ) imparted by the actuator 75 serves to adjust the traction of the continuous flexible member 31 and it can be coordinated with the corresponding movement imparted by the corresponding actuator 75 of the second support 32.2. The displacement imparted by the actuator 77 by means of the eccentric 73.3 can serve to correct displacements of the continuous flexible member 31 parallel to the rotation axis of the guide rollers 32, 35, for example a lateral slip. The homologous displacement of the support 32.2 on the side of the second articulated arm 25 is not necessary.

[0129] Figures 24A to 28B Further details are shown which are useful for understanding the control of the traction and of the position of the continuous flexible member 31. More particularly, Figure 24A and 24BDetails of the articulated arms 23, 25 and of the continuous flexible member 31 guided around the guide rollers 32 and 35 are shown in an isometric view. Figure 24A and 24B Sensors for detecting the displacement of the continuous flexible member 31 are indicated, which provide signals to the central unit 101 controlling the above-mentioned actuators to keep the continuous flexible member 31 in the correct position.

[0130] In the embodiment shown, at least one respective sensor 103, for example a magnetic sensor, is arranged on each articulated arm 23, 25, which detects the twisting of the continuous flexible member 31. For this purpose, elements detectable by the sensor 103, for example two magnets 105, are inserted along the two edges of the continuous flexible member 31. The two magnets 105 are arranged in a line orthogonal to the edges of the continuous flexible member 31. Therefore, if the continuous flexible member 31 does not show twisting or bending, they pass simultaneously in front of the respective sensor 103. The twisting of the continuous flexible member 31 causes the two magnets 105 to mutually offset along the direction of advancement of the continuous flexible member 31. This is detected by the delay of the signal of one sensor 103 with respect to the signal of the other sensor, and this provides information to the central unit 101 about the need to correct the two actuators 75 by means of differential actuation.

[0131] A possible lateral sliding of the continuous flexible member 31 can be detected with a respective arrangement of sensors. In the embodiment shown, a sensor 107 is provided on one of the articulated arms 23, 25 and more specifically on the articulated arm 23 in the example shown. The sensor 107 can be an optical sensor, for example comprising one or more photoelectric elements arranged orthogonal to the edges of the continuous flexible member 31 to identify its position. For example, a fiber-optic sensor can be used, with a plurality of optical fibers along a direction orthogonal to the edges of the continuous flexible member, which detects the optical signal from an opposite emitter located on the opposite face of the continuous flexible member 31. A lateral sliding of the continuous flexible member 31 in one direction or the other causes a variation in the number of photoelectric elements or optical fibers that see the optical signal emitted by the opposite emitter. The central unit 101 uses the signals obtained to emit control signals for the linear actuators 77 for correcting any sliding.

[0132] The possibility of using a combined movement of the actuators 77 and 75 to correct the sliding and twisting movements cannot be excluded.

[0133] Figure 25A and 25B The control of the traction of the continuous flexible member is shown in more detail how it is carried out by means of the simultaneous actuation of the actuators 75.

[0134] In Figure 25A , the continuous flexible member 31 is not stretched, while in Figure 25BIn this way, the first guide roller 32 is stretched due to the effect of the equal elongation of the two actuators 75 and the consequent movement of the first guide roller 32 away from the second guide roller 35, so as to keep the axes of the two guide rollers parallel to each other.

[0135] Figure 26 and 27 The displacement of the first guide roller 32 caused by the linear actuator 77 to correct the lateral sliding movement of the continuous flexible member is shown. More specifically, Figure 26 is a rear view according to Figure 27 of the XXVI-XXVI, while Figure 27 is a side view according to Figure 26 of the XXVII-XXVII of the extrusion unit 21. The two tilted positions of the first guide roller 32 are indicated with the reference numerals 32X and 32Y. For greater clarity, the displacement is represented much greater than the actual displacement.

[0136] Figure 28A and 28B The displacement of the first guide roller 32 caused by the differential stroke of the actuators 75 to correct possible distortions of the continuous flexible member 31 is shown in a top view of the extrusion unit 21. The positions of the first guide roller 32 tilted in opposite directions obtained by means of the differential action of the actuators 75 are indicated with the reference numerals 32Z and 32W. As in Figure 26 and 27 , the displacement is also shown much greater than the actual displacement in Figure 28A , 28B for greater clarity.

[0137] The application has been described according to various specific embodiments. However, it is evident that many modifications, changes and omissions can be made by a person skilled in the art without departing from the spirit and scope of the application as defined by the following claims.

Claims

1. A single-face corrugating machine (1) for manufacturing single-face corrugated cardboard, comprising: Support frame (3); A first corrugated roll (15) and a second corrugated roll (17), the first corrugated roll and the second corrugated roll meshing with each other and associated with the support frame (3); A pivot structure pivotally connected to a support frame (3) about a pivot axis (29), wherein the pivot structure comprises: a first pivot arm (23) pivotally connected to the support frame (3) by means of a first hinge system located on a first side of the single-face corrugator (1); and a second pivot arm (25) located on a second side of the single-face corrugator (1); wherein the first pivot arm (23) and the second pivot arm (25) are rigidly connected to each other; A first guide roller (32), having a first axis of rotation (33), is supported on the first pivot arm (23) and the second pivot arm (25); The second guide roller (35), having a second axis of rotation (37), is supported on the first pivot arm (23) and the second pivot arm (25); A continuous flexible member (31) is guided around the first guide roller (32) and the second guide roller (35); A first actuator (41) is associated with the first pivot arm (23) and forms a first constraint between the first pivot arm (23) and the load-bearing frame (3); A second actuator (43) is associated with the second pivot arm (25) and forms a second constraint between the second pivot arm (25) and the support frame (3); The first actuator (41) and the second actuator (43) are capable of bringing the pivot structure to a working position and a raised position, in which the first guide roller (32) and the second guide roller (35) are adjacent to the second corrugated roller (17), and in the raised position the first guide roller (32) and the second guide roller (35) are spaced apart from the second corrugated roller (17); and wherein the first hinge system forms a constraint with the support frame (3), which is capable of cantilevering the first guide roller (32) and the second guide roller (35) when the second pivot arm (25) is released from the support frame (3), thereby allowing the continuous flexible member (31) to be removed from the second side of the single-face corrugator (1).

2. The single-face corrugating machine (1) according to claim 1, wherein the second pivot arm (25) is pivotally connected to the support frame (3) by means of a second hinge system (25.1), wherein the second pivot arm (25) is connected to the support frame (3) by means of a removable member (25.2) which is detachable to allow removal of the continuous flexible member (31).

3. The single-sided corrugating machine (1) according to claim 1, wherein the pivot axis (29) is spaced apart from the first rotation axis (33) of the first guide roller (32) and the second rotation axis (37) of the second guide roller (35).

4. The single-sided corrugating machine (1) according to claim 2, wherein the pivot axis (29) is spaced apart from the first rotation axis (33) of the first guide roller (32) and the second rotation axis (37) of the second guide roller (35).

5. The single-sided corrugating machine (1) according to claim 1, wherein the first hinge system comprises two hinges (23.2, 23.3) spaced apart from each other along the pivot axis (29) of the pivot structure.

6. The single-sided corrugating machine (1) according to claim 2, 3 or 4, wherein the first hinge system comprises two hinges (23.2, 23.3) spaced apart from each other along the pivot axis (29) of the pivot structure.

7. The single-face corrugating machine (1) according to any one of claims 1 to 5, wherein the first corrugating roller (15) and the second corrugating roller (17) are mounted on an interchangeable roller box (13) which can be removed from the support frame (3).

8. The single-face corrugating machine (1) according to any one of claims 1 to 5, wherein the supporting frame (3) includes a fixed support (61) positioned on a first side of the single-face corrugating machine (1) and working together with a movable support (63), the movable support being integrally integrated with the pivot structure.

9. The single-face corrugating machine (1) according to claim 8, wherein in the lowered position of the pivot structure, the fixed support (61) and the movable support (63) define the angular position of the pivot structure, and the position of the pivot structure is lower than the working position in which the continuous flexible member (31) and the second corrugated roller (17) work together.

10. The single-face corrugating machine (1) according to any one of claims 1 to 5, wherein the first actuator (41) and the second actuator (43) are linear actuators, with their respective first ends (41.1, 43.1) constrained to the bearing frame (3) and their respective second ends (41.2, 43.2) constrained to the pivot structure.

11. The single-face corrugating machine (1) according to claim 10, wherein the second actuator (43) is constrained to the second pivot arm (25) by means of a reversible connector to release the second end (43.2) of the second actuator (43) from the second pivot arm (25).

12. The single-face corrugating machine (1) according to any one of claims 1 to 5, wherein the first pivot arm (23) carries a motor (39) for driving one of the first guide roller (32) and the second guide roller (35).

13. The single-face corrugating machine (1) according to claim 12, wherein the motor (39) is mechanically connected to the second guide roller (35); and wherein the second guide roller (35) is arranged at a greater distance from the pivot axis (29) of the pivot structure than the first guide roller (32).

14. A method for operating a single-face corrugating machine (1) according to any one of the preceding claims, wherein the following steps are performed to replace the continuous flexible member (31): Move the first guide roller (32) and the second guide roller (35) away from the second corrugated roller (17); The second actuator (43) is released from the second pivot arm (25) and the second pivot arm (25), the first guide roller (32) and the second guide roller (35) are cantilevered by means of the first pivot arm (23); Remove the continuous flexible member (31) from the first guide roller (32) and the second guide roller (35); Insert new continuous flexible members (31) into the first guide roller (32) and the second guide roller (35); Connect the second actuator (43) to the second pivot arm (25); The pivot structure is lowered toward the second corrugated roller (17); The continuous flexible member (31) is pressed against the second corrugated roller (17).

15. The method of claim 14, wherein the second pivot arm (25) is pivotally connected to the load-bearing frame (3) by means of a second hinge system (25.1), the method further comprising the step of: Before removing the continuous flexible member (31) from the first guide roller (32) and the second guide roller (35), the second pivot arm (25) is released from the second hinge system (25.1), which is hinged to the support frame (3) via the second hinge system (25.1); After inserting the new continuous flexible member (31) onto the first guide roller (32) and the second guide roller (35), the second pivot arm (25) is connected to the second hinge system (25.1).

16. A single-face corrugating machine (1) for manufacturing single-face corrugated cardboard, comprising: Support frame (3); A first corrugated roll (15) and a second corrugated roll (17), the first corrugated roll and the second corrugated roll meshing with each other and associated with the support frame (3); An extrusion unit (21), which is pivotally connected to the bearing frame (3) about a pivot axis (29), and includes: -First pivot arm (23); - A second pivot arm (25) is rigidly connected to the first pivot arm (23); - A first guide roller (32), having a first axis of rotation (33), is supported on the first pivot arm (23) and the second pivot arm (25); - A second guide roller (35), having a second axis of rotation (37), is supported on the first pivot arm (23) and the second pivot arm (25); - A continuous flexible member (31) is guided around the first guide roller (32) and the second guide roller (35); The first pivot arm (23) can cantileverly supports the second pivot arm (25), the first guide roller (32), and the second guide roller (35) on the support frame (3) to allow the continuous flexible member (31) to be removed from the side of the second pivot arm (25).

Images