ALIGNING GROUP OF CONTINUOUS CARDBOARD BELTS

Description

The present invention concerns the field of single-or double-wave in-line corrugated cardboard production plants. The invention was developed with particular regard to an aligning assembly of a continuous strip of cardboard. In-line corrugated cardboard production plants known in the art comprise one or more corrugating assemblies, each of which is fed by continuous strips of paper. Each corrugating assembly comprises a corrugator, referred to as a “single facer,” which is particularly suitable for creating corrugations on one of the continuous strips of paper and coupling the corrugated strip to a continuous paper strip, referred to as a “cover,” producing a continuous composite cardboard strip, referred to as a “canneté.”

Corrugated cardboard production plants also comprise a plurality of processing stations, arranged in succession to each other and in sequence along a predetermined card-movement path, which receive the canneté produced by the corrugating assembly and allow finalising the production of a continuous strip of corrugated cardboard.

For example, plants are known to comprise one or more coupling assemblies that compose a continuous strip of corrugated cardboard by combining, e.g., by gluing, one or more cannetes and a further continuous strip of paper, referred to as the second cover. Each continuous strip of corrugated cardboard therefore comprises a first canneté to which one or more cannetés can be superimposed and, finally, a second cover.

Plants are known to comprise a double backer, arranged downstream of the one or more coupling assemblies along the card-movement path, to stabilise the coupling between the continuous strips of paper. The function of the double backer is to drag the papers from a single facer and a second cover unwinder by simultaneously applying heat and mechanical pressure in order to achieve a firm bonding between several layers of papers and form a continuous strip of corrugated cardboard. For this purpose, the double backer may comprise heating plates and a belt or pressing rollers to heat and press the continuous strip of corrugated cardboard, respectively, to consolidate the bonding between the sheets that compose it and that define overall a sliding plane on which the continuous strip of corrugated cardboard is advanced.

There are many solutions and many forms of double backer comprising hot and cold sections, pressure sections and pull sections. Depending on the case, the incoming cannete can be arranged with the waves facing downwards or with the waves facing upwards.

It is well known how the continuous strip of cardboard that is formed within a double backer—whether it is composed of a single canneté or two cannetés coupled to the second cover—tends to change its position on the sliding plane. In particular, defining as the median axis of the continuous strip of corrugated cardboard the axis that passes through the centre of the continuous strip of corrugated cardboard and that divides it into two equal halves, and defining as the median axis of the sliding plane the axis that passes through the centre of the sliding plane and that divides it into two equal halves, in an ideal situation the median axis of the continuous strip of cardboard is aligned with the median axis of the sliding plane. In reality, however, the median axis of the continuous strip of cardboard exiting the double backer may be misaligned with the median axis of the sliding plane, for example, offset laterally or rotated clockwise or counterclockwise. The most typical causes of these deviations are, for example, the skidding of the belts in the double backer, imperfections of the papers, imperfections or mechanical tolerances between the rollers and the sliding plane, wear or malfunction of the dragging rollers, incorrect dimensions of one of the papers, etc.

These deviations create significant problems in the subsequent steps of in-line corrugated cardboard production. In fact, downstream of the double backer, the continuous strip of corrugated cardboard must be cut and creased longitudinally in order for the final product to have the desired dimensions. Sometimes, corrugated cardboard has to be produced in sheets and then also cut crosswise.

If the continuous strip of corrugated cardboard arrives at the cutting and creasing stations with a median axis that is not aligned with that of the sliding plane, the cut and creased corrugated cardboard will have unwanted and unsuitable dimensions, and/or shapes.

One of the solutions of known type provides for the presence of swivel rollers or wheels at the outlet of the double backer. By changing the orientation of one or more rollers or wheels, the outgoing continuous strip of corrugated cardboard is displaced and/or rotated so that its median axis is again aligned with the median axis of the sliding plane along the direction of advancement. Another well-known solution aimed at solving this problem is to have downstream of the double backer a longitudinal cutting and creasing device for corrugated cardboard, called “slitter scorer,” mounted on wheels. The wheels allow the slitter scorer to be displaced sideways, e.g., by a few centimetres, in order to support the skidding of the incoming continuous strip of cardboard and allow correct cutting and creasing.

However, known solutions, such as those above, continue to present some drawbacks. For example, the swivel rollers or wheels tend to create ripples or creases on the papers due to the friction caused by the swivel rollers or wheels when attempting to displace the continuous strip of corrugated cardboard. The slitter scorer, on the other hand, tends to displace the continuous strip of corrugated cardboard further as a result of the cutting action of the blades used.

The need has therefore arisen to overcome the aforementioned drawbacks of the prior art, and to realise an aligning assembly of a continuous strip of corrugated cardboard that is able to compensate for possible alignment errors, that has a limited footprint within a simple, rational and low-cost solution, and that allows for an optimisation of the number of resources. In view of this need, the Applicant has, according to the invention, thought of realising an aligning assembly of a continuous strip of paperboard as defined in the main claim. The dependent claims define further innovative features of the present invention.

Further features and advantages of the present invention will be apparent from the following detailed description. It is to be understood that elements and characteristics of one embodiment may conveniently be incorporated into other embodiments without further clarifications.

Reference will now be made in detail to the various embodiments of the invention, with particular reference to the attached figures, in which:

FIG. 1 is a schematic top view of an aligning assembly of a continuous strip of cardboard according to the present invention;

FIG. 2 is a schematic side view of the aligning assembly of FIG. 1;

FIG. 3 is a schematic top view of the aligning assembly of FIG. 1 in a first operating position;

FIG. 4 is a schematic top view of the aligning assembly of FIG. 1 in a second operating position;

FIG. 5 is a schematic side view of a double backer comprising an aligning assembly according to the present invention; and

FIG. 6 is a schematic top view of a double backer and aligning assembly of FIG. 5.

Each example is provided merely to illustrate the invention and is not intended as a limitation thereof. For example, the technical features illustrated or described because they belong to one embodiment may be implemented in, or in association with, other embodiments in order to generate a further embodiment. It is understood that the present invention is comprehensive of such modifications and variants.

An aligning assembly of a continuous strip of cardboard according to the present invention, and generally referred to as 20, comprises a transport device, i.e., a dragging device 30, configured to transport, i.e., drag, a continuous strip of corrugated cardboard 5 along a direction of advancement. The aligning assembly 20 can be placed inside a corrugated cardboard production plant, downstream and upstream of one or more processing stations.

In order to improve understanding of the description that follows, it is defined as:

• • direction of advancement of the continuous strip of corrugated cardboard 5, an axis X₁-X₁ passing through the centre of the continuous strip of corrugated cardboard 5 and dividing it into two equal halves;
  • sliding plane of the dragging device 30, a plane P on which a continuous strip of cardboard 5 is dragged;
  • median axis of the dragging device 30, an axis X₀-X₀ passing through the sliding plane of the dragging device 30 and dividing it into two equal halves.

According to the present invention, the dragging device 30 is selectively movable to change the orientation of the direction of advancement X₁-X₁ of the continuous strip of corrugated cardboard 5. More in particular, the dragging device 30 is selectively movable to change the orientation of the median axis X₀-X₀ of the dragging device 30, so as to change the direction of advancement X₁-X₁ of the continuous strip of corrugated cardboard 5, as clearly visible of FIGS. 3 and 4.

According to one embodiment of the present invention, the dragging device 30 comprises a main frame 32, preferably elongated along the paper movement path, i.e., along the median axis X₀-X₀ of the dragging device 30, and comprising a first end 33 and a second end 35.

The dragging device 30 comprises at least one pair of rollers 34, 36, engaged to the frame 32, each at a respective end 33, 35, and supported around a rotation axis.

The dragging device 30 also comprises a belt 38 mounted on the pair of rollers 34, 36, constituting the sliding plane P of the dragging device 30. Preferably, the belt is an aspirated belt 38, connected to a suction system (not illustrated), to facilitate the clinging of the continuous strip of cardboard 5 to the outer surface of the belt 38.

Preferably, at least one roller 34 of said at least one pair of rollers is motorised, by means of an actuator 37, and configured to move the belt 38 and to drag the continuous strip of corrugated cardboard 5 along the median axis (X₀-X₀) of the dragging device (30), and the other roller 36 is idle. Of course, it is possible to provide dragging devices comprising more than two rollers, and/or with two or more motorised rollers without thereby departing from the scope of the present invention.

The first end 33 of the frame 32 may be referred to as the inlet, or inlet position, of the aligning assembly 20, as it is arranged facing processing stations arranged upstream of the aligning assembly 20 with respect to the direction of advancement of the continuous strip of cardboard, and is therefore configured to receive the continuous strip of cardboard 5. The second end 35 of the frame 32 may be referred to as the outlet, or outlet position, of the aligning assembly as it is arranged facing processing stations arranged downstream of the aligning assembly 20 with respect to the direction of advancement of the continuous strip of cardboard.

The aligning assembly 20 comprises at least one actuator connected to the dragging device 30 and configured to change the orientation of the median axis X₀-X₀ of the dragging device 30. For example, the actuator may be a jack connected to the frame 32 and configured to displace the ends 33, 35 of the frame 32 and change the orientation of the median axis X₀-X₀ of the dragging device 30 and, thus, of the belt 38.

According to the embodiment illustrated of FIG. 1, the aligning assembly 20 comprises one or more pairs of guides 40, 40′ extending along paths incident to the median axis X₀-X₀ of the dragging device 30, the dragging device 30 being movably disposed on said guides 40, 40′. Specifically, a first pair of guides 40 extends along a first path C₁-C₁, and a second pair of 40′ guides extends along a second path C₂-C₂.

The term “guide” is understood in this description to mean any mechanism adapted to make one of its members describe predetermined trajectories or paths. In the case where the mechanism consists of only two members, the fixed member acts as a guide and regulates the movement of the movable member. This term is also understood to comprise linear guide systems in which the fixed member may consist of a support element, e.g., a track, rail or other similar elements comprising at least one sliding plane, and in which the movable member may consist of, for example, rollers, needle rollers, tapered rollers, wheels or other technically equivalent elements. According to the embodiment illustrated in the figures, the development of each path C₁-C₁, C₂-C₂ is preferably curvilinear. Alternatively, the development of each path C₁-C₁, C₂-C₂ can be straight. According to other embodiments, the aligning assembly 20 comprises only two guides 40, 40′, and each extends along the full width of frame 32 along a respective path C₁-C₁, C₂-C₂.

The aligning assembly 20 also comprises one or more supports 44, 46, separated and disengaged from the dragging device 30, on which the guides 40, 40′ are mounted.

Each end of dragging device 30 lies on a respective guide 40, 40′. With reference to the illustrated embodiment, the first end 33 of the frame 32 rests on a first pair of guides 40, and the second end 35 of the frame 32 rests on a second pair of guides 40′. Also according to this embodiment, the dragging device 30 comprises a plurality of movable members, for example, but not limited to wheels 42, engaged at the ends 33, 35 of the frame 32, arranged to slide on the guides 40, 40′, and configured to allow the ends 33, 35 of the frame 32 to slide along the guides 40, 40′.

According to embodiments of the present invention, the curvilinear paths C₁-C₁, C₂-C₂ on which the one or more pairs of guides 40, 40′ extend correspond to a respective portion of an arc of a circumference whose centre R is arranged external to the aligning assembly 20.

According to embodiments, the centre R is unique for both curved paths. In this case, the respective portions of the circumferential arc C₁-C₁, C₂-C₂ may have a different radius of curvature due to the different distance of the centre R from the respective guides 40, 40′, i.e., from the ends 33, 35 of the frame 32.

According to other embodiments, the aligning assembly 20 comprises two distinct centres of rotation, one for each curvilinear path C₁-C₁, C₂-C₂. Of course, in any of the embodiments described above, the one or more centres R may be arranged at any predetermined distance from the dragging device 30, and thus from the frame 32. This distance will determine the curvilinear development of the respective portion of the circumferential arc C₁-C₁, C₂-C₂. Preferably, the centre R is placed as far as possible from the frame 32, so that the radius of curvature of the respective portions of the circumferential arc C₁-C₁, C₂-C₂, corresponding to the curvilinear development of each curved guide 40, 40′, is as small as possible.

These features are particularly advantageous in that the cardboard dragged by the aligning assembly 20 is a continuous strip and is moved at a predetermined speed, so its alignment is made quicker and more effective by the displacement, also independent, of each end of the dragging device 30. In fact, considering the position of the centre R outside the aligning assembly 20 and defining as the radius of the circumferences on which the curvilinear paths C₁-C₁, C₂-C₂ an axis passing through R and through the centre of the dragging device 30, it is evident that the displacement of the dragging device 30 is comparable to the oscillation of a pendulum, which is particularly effective in changing the orientation of a continuous strip in motion without causing an undesirable folding or distortion of the papers composing the continuous strip.

According to some embodiments, the aligning assembly of a continuous strip of cardboard 20 according to the present invention may comprise a control system, feedback, configured to determine the deviation of the direction of advancement X₁-X₁ of the continuous strip of corrugated cardboard 5 with respect to the median axis X₀-X₀ of the dragging device 30. The control system is preferably arranged at the outlet of the aligning assembly 20 and may be connected to the at least one actuator of the aligning assembly 20, so as to selectively activate the actuator and change the orientation of the dragging device 30, i.e., to displace the dragging device 30 by a predetermined extension and according to a predetermined direction along the guides 40, 40′, and allow the continuous strip of corrugated cardboard 5 to align correctly prior to the next cutting and creasing step.

The control system may comprise sensors, or other devices for detecting the position of the continuous strip of corrugated cardboard 5, preferably arranged after the exit of the aligning assembly 20. Of course, the control system may comprise a computer or electronic circuit connected to the detection devices and the actuator, and configured to receive incoming data from the detection devices, process said data and send a command to the actuator to change the orientation of the dragging device 30.

In use, a continuous strip of cardboard 5, exiting an operating station of a corrugated cardboard production plant arranged upstream of the aligning assembly 20, e.g., but not in a limiting manner, a double backer 10, is transported to the aligning assembly 20 according to a predetermined direction of advancement X₁-X₁.

Subsequently, the dragging device 30 is displaced so as to change the orientation of the median axis X₀-X₀ of the dragging device 30 and to change the direction of advancement X₁-X₁ of the continuous strip of corrugated cardboard 5.

The present invention also concerns a double backer comprising an integrated paper aligning assembly. With particular reference to FIG. 5, an in-line corrugated cardboard production plant may comprise a double backer 1, comprising, in turn, heating plates and a pressing belt or rollers to heat and press the strip of corrugated cardboard, respectively, and thus consolidate the bonding between the sheets that compose it. A double backer may comprise hot sections or cold sections, or a combination of these. There are numerous embodiments of hot sections of a double backer of known type, so only the main technical characteristics are given below. According to one of its possible embodiments, the double backer 1 comprises a hot section 10 comprising one or more heating zones configured to heat the at least one cannete and a cover, and one or more pressure zones configured to stabilise, or consolidate, the coupling between said at least one cannete and said cover and to make a continuous strip of corrugated cardboard 5. The papers are moved through said zones on a sliding plane along a direction of advancement X-X.

The one or more heating zone(s) may comprise one or more heating devices configured to directly come into contact with one of the cannete and the cover, and preferably the cover, so that at least the cover itself can be heated, and preferably both the cover and the canneté can be heated. Such heating devices may be, for example, one or more plates comprising a plurality of internal channels connected to a hot fluid supply system. For example, said internal channels are configured to be traversed by steam so as to heat the first heating plates and, thus, to heat both the cover and the canneté and to bring them to a temperature substantially comprised between 80° C. and 200° C. and, preferably, comprised between 80° C. and 120° C.

The one or more pressure zones may comprise pressure devices provided with pressure elements connected to a pressure mechanism, for example, one or more pneumatic pistons, configured to exert a predetermined force on the cover.

According to other embodiments, the one or more pressure zones may also comprise heating devices, for example a dispensing device configured to dispense steam on the sheets of paper material, for example one or more nozzles, connected to a supply system, adapted to dispense a fluid, usually steam.

The double backer 1 according to the present invention further comprises a cold section, consisting of an aligning assembly 20 as described above, arranged downstream and successively to the hot section 10.

In use, a canneté—single-wave or double-wave—and a cover enter the hot section 10 of the double backer 1 so that the median axis X₁-X₁ of the continuous strip of corrugated cardboard 5 is aligned with the median axis X-X of the sliding plane of the hot section 10 of the double backer.

As mentioned above, and with reference to FIG. 3, for various reasons the continuous strip of corrugated cardboard 5 may exit from the hot section with a median axis X₁-X₁ not aligned with the median axis X₀-X₀ of the sliding plane P of the aligning assembly 20. In FIG. 3, the median axis X₁-X₁ of the continuous strip of corrugated cardboard 5 is shifted to the right clockwise with respect to the median axis X₀-X₀.

Next, and with reference to FIG. 4, the dragging device 30 is displaced along the respective guides 40, 40′, by means of the one or more actuators so as to rotate the median axis Xo-Xo. In FIG. 4, the median axis Xo-Xo of the dragging device 30 is shifted to the left in an anti-clockwise direction on the sliding plane P.

This displacement causes the displacement of the continuous strip of corrugated cardboard 5 so that the median axis X₁-X₁ of the continuous strip of corrugated cardboard 5 is again aligned with the median axis X-X of the double backer of the hot section 10.

As is clear from the above description, the double backer with integrated carton alignment makes it possible to maintain, or even realign, a continuous strip of corrugated cardboard so that at the exit it is always positioned at the same point, normally at the median axis of the sliding plane.