Embossing device for processing a paper web

Abstract

An embossing device includes an engraved steel roller (UA) and a rubber counter roller (UG), which applies a predetermined thrust (T) to the engraved roller (UA) by means of a corresponding actuator (AG), and which also has associated bonding rolls (M) which apply a predetermined radial thrust (C) to the same engraved roller (UA) by means of their respective actuators. The thrust (T) applied by the counter roller to the engraved roller (UA) is contained in a plane (PT) passing through the rotation axis (X) of the respective engraved roller (UA) and is inclined at a predetermined angle (a) with respect to a plane (PA) passing through the same rotation axis (X) and also passing through the axis (Y) of the bonding roll, thereby generating a counter thrust (TX) opposite to the thrust (C). The bonding roll (M) is made of steel.

Description

[Technical Field]

[0001] The present invention relates to an embossing device for converting a paper web. [Background technology]

[0002] More particularly, the invention relates to a type of apparatus comprising two operating groups, at least one of which comprises an engraved steel roller and a rubber counter roller that cooperate to emboss each paper ply, while the other operating group can be configured as either an embossing group or a group that supplies unembossed plies. The two plies can be joined by gluing. The final joining of the plies is facilitated by the use of a joining roll with a rubberized surface that applies pressure to the plies downstream of the operating group. This type of operating apparatus is typically used in so-called paper converting plants that produce articles such as toilet paper rolls, kitchen paper rolls, and more generally, products derived from paper processing.

[0003] The drawback of using an operating unit configured in this way is that in order to achieve an effective mutual bonding of the plies, it is necessary to exert considerable pressure on the bonding roll, which often dictates re-embossing to modify the embossing obtained by the two embossing groups and requires excessive energy compared to current production requirements. Furthermore, it is difficult to control the rotation of the bonding roll, since it is dragged by the rotation of the imprinting roller it acts on.

[0004] Patent Document 1 discloses an embossing device for processing a web of paper material, the embossing device comprising an embossing roller, a pressure roller coated with an elastically yielding material that cooperates with the embossing roller, and at least one actuator that presses the embossing roller and the pressure roller together. In this embossing device, the pressure roller coated with an elastically yielding material is configured and controlled so that the paper material can be re-embossed according to planned production. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US2013 / 0099417A1 Summary of the Invention [Problem to be solved by the invention]

[0006] A primary object of the present invention is to provide an embossing device that can utilize bonding rolls that avoid re-embossing of the plies. Another object of the present invention is to provide an embossing device that can reduce the pressure acting on the paper plies. Yet another object of the present invention is to provide an embossing device that can control the rotation of the bonding rolls. [Means for solving the problem]

[0007] This effect is achieved according to the invention by adopting the idea of ​​providing a machine having the features set out in claim 1. Other features of the invention are the subject of the dependent claims.

[0008] Further advantages and features of the present invention will be better understood by those skilled in the art from the following description and accompanying drawings, which are provided by way of illustration and are not to be considered in a limiting sense. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic side view showing a possible operating configuration of the device according to the present invention; [Figure 2A] 1 is a schematic side view of an apparatus according to the present invention, with some components not shown in order to better highlight other components; [Figure 2B] FIG. 2B is a detailed view of FIG. 2A. [Figure 3] FIG. 10 is a schematic diagram showing a state in which the contact between the marking roller and the bonding roll of the second embossing group is appropriate. [Figure 4] FIG. 10 is a schematic diagram illustrating a state in which the contact between the marking roller and the bonding roll of the second embossing group is inappropriate. [Figure 5] 2 is a schematic diagram showing forces acting on a second embossing group in the embossing device configured as in FIG. 1; FIG. [Figure 6] FIG. 1 is a schematic diagram showing a side view of an undeformed imprinting roller (UA) in solid lines and the deformations due to thrust forces exerted by the respective counter rollers in dotted lines. [Figure 7] FIG. 2 is a schematic diagram illustrating a first alternative possible operating configuration of the device according to the present invention. [Figure 8] FIG. 10 is a schematic diagram illustrating a second alternative possible operating configuration of the device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Returning to its essential structure and with reference to the attached drawings, in terms of possible operating configurations, the embossing device (EU) according to the invention may, for example, include the following configurations: - first embossing group (L); - second embossing group (U); -Gluing group (G); a structure (S) configured to support said gluing group (G), said first embossing group (L) and said second embossing group (U).

[0011] Referring to the example shown in FIG. 1, the first embossing group (L) is positioned below the second embossing group (U).

[0012] Each of the embossing groups (L, U) comprises an engraved steel roller (LA, UA) and a respective rubber counter-roller (LG, UG). The rollers (LA, LG, UA, UG) are arranged horizontally between two opposing walls of the structure (S). Preferably, the rollers (LA, LG, UA, UG) are removably attached to the structure (S) by removable connecting members known per se. For example, the rollers (LA, LG, UA, UG) can be connected to the structure (S) by removable or retractable collar members acting on the ends of the rollers themselves. Referring to the arrangement shown in FIG. 1, the engraved rollers (LA) of the first embossing group (L) are above the respective rubber counter-rollers (LG), while the engraved rollers (UA) of the second embossing group (L) are below the respective rubber counter-rollers (UG).

[0013] The embossing device (EU) further comprises bonding rolls (M) also supported by the structure (S) and oriented with their axes parallel to the axes of the rollers (LA, LG, UA, UG). The bonding rolls (M) are located in front of the stamping roller (UA) of the second embossing group (U) in relation to the direction of travel of the paper plies (P1, P2). The gluing group (G) is located opposite the bonding rolls (M), i.e., behind the stamping roller (UA) of the second embossing group (U). The outer surface of the bonding roll (M) is smooth, i.e., not stamped.

[0014] For example, the gluing group (G) comprises a tank (GT) containing adhesive and a first horizontal roller (HR) which takes adhesive from the tank (GT) and transfers it by contact to a second horizontal roller (HG) which transfers it to the paper ply (P2), as will be further described below. In a known manner, the rollers (HR, HG) of the gluing group rotate at a predetermined speed about their respective axes, controlled by corresponding electric motors (not shown in the drawings), to take adhesive from the tank (GT) and distribute it on the paper ply (P2). Each of the rubber counter rollers (LG, UG) is pressed against a respective imprint roller (LA, UA) by a respective actuator (AL, AG) acting on the end of the same counter roller.

[0015] In operation, the embossing groups (L, U) generate embossments in the respective plies (P1, P2) in a manner known per se. A ply (P1) passes between the rollers (LG, LA) of the first embossing group (L), and another ply (P2) passes between the rollers (UG, LG) of the second embossing group (U). Furthermore, the second ply (P2) contacts the second roller (HG) of the gluing group (G), and both plies (P1, P2) pass between the imprinting rollers (LA, UA). Thus, the plies (P1, P2) are embossed and glued together, and a web of paper material is produced consisting of the embossed and glued plies (P1, P2). The web of paper material (W) emerges from the nip formed by the imprinting roller (UA) and the bonding roll (M).

[0016] According to the invention, the rubber counter rollers (UG) of the second embossing group (U) are arranged so as to apply a thrust (T) contained in a plane (PT) passing through the rotation axis (X) of the respective imprinting roller (UA) and inclined at an angle (a) to a plane (PA) passing through said same rotation axis (X) and also through the longitudinal axis (Y) of the bonding roll (M). In fact, with reference to Figure 1, the rubber counter rollers (UG) of the second embossing group (U) are in a rear position relative to their respective imprinting rollers (UA) in relation to the direction of travel of the corresponding web (P2).

[0017] The bonding roll (M) is a steel roller that is pressed toward the stamping roller (UA) of the second embossing group (U) by its respective actuator (AM). Figure 5 shows the thrust (C) that the bonding roll (M) exerts on the stamping roller (UA) of the second embossing group (U). Figure 5 also shows the thrust (T) and the rear position of the counter roller (UG) relative to the corresponding stamping roller (UA), as well as the horizontal and vertical components (TX and TY) of the thrust (T). In the following description, the horizontal component is referred to as the counter thrust. The thrust (C) is of the same order of magnitude as the counter thrust (TX). In this operating state, the loads acting on the stamping roller (UA) and the bonding roll (M) determine the substantial parallelism of their axes and, therefore, the correct contact between their surfaces, defining the nip (N) where the web (W) intersects. This state is shown in Figure 3. However, in the absence of the thrust force (TX), due to the deflections experienced by the rollers (M, UA), the contact between the outer surfaces of the rollers themselves would be inadequate, as shown diagrammatically in Figure 4, and as a result the intervention of the bonding roll would be ineffective. Furthermore, it would be advantageous to optimise the contact between the roller (HG) and the imprinting roller of the second embossing group (U), thus improving the energy efficiency of the system.

[0018] 6 shows in solid lines the undeformed stamping roller (UA) and in dotted lines the deformations it has undergone as a result of the thrust (T) applied by the respective counter roller, where the symbol (d) denotes the radial deflection of said roller (UA).

[0019] If necessary, the joining roll (M) can be a crowning roller.

[0020] The device according to the invention synergistically combines the following features: - the thrust (T) is directed obliquely, i.e. along the aforementioned plane (PT); -The joining roll (M) is made of steel.

[0021] It goes without saying that the planes (PT) and (PA) mentioned above are geometric planes, not physical planes.

[0022] The rotation of the bonding roll (M) is controlled by a corresponding electric actuator (schematically represented by a dotted circle 1M in FIG. 1).

[0023] In another operating configuration, the first operating group (L) can be replaced by a device for feeding an unembossed web (P1), which in the example of Figure 8 comprises a roller (RA) for guiding said web (P1) into the nip formed by the marking roller (UA) and the bonding roll (M) of the group (U).

[0024] In another possible operating configuration, as shown in the schematic diagram of Figure 7, in addition to the plies (P1) and (P2), a further ply (P3) is supplied by means of a roller (RB) which guides the further ply (P3) into the nip between the distribution roller (HG) of the gluing group (G) and the stamping roller (UA), in which case the device produces a web (W) comprising the plies (P1), (P2) and (P3).

[0025] The device according to the invention can therefore be constructed in a variety of configurations depending on the characteristics required of the web (W) emerging from the device.

[0026] The tank (GT) can contain water instead of adhesive or ink.

[0027] The material placed in the tank (GT) promotes bonding of the plies that form the web (W).

[0028] The final joining of the plies (P1, P2; P1, P2, P3) is determined by passing through the nip formed by the roller (UA) and the joining roll (M).

[0029] The steel bonding roll (M) avoids the re-embossing of the ply that would otherwise occur if a rubber-coated bonding roll with elastically yielding properties were used: in other words, due to the high stiffness of steel compared to rubber, i.e. compared to the elastically yielding material with which prior art bonding rolls are coated, a linear pressure in the nip formed by the roller (UA) and the bonding roll (M), typically of the order of magnitude between 12 kg / cm and 25 kg / cm, prevents further embossing of the paper ply.

[0030] From the above description, it is clear that the embossing device (EU) according to the present invention is constructed as follows: The embossing device (EU) of the invention comprises an embossing group (U) for the embossing of each ply (P2) associated with at least one supply device for a further ply (P1), and a group (G) for the distribution of a liquid that promotes the bonding of said plies to one another, The embossing group (U) comprises a steel stamping roller (UA) and a rubber counter roller (UG), the rubber counter rollers (UG) of the embossing group (U) exert a predetermined thrust (T) on the respective imprinting rollers (UA) by means of their respective actuators (AG); the stamping rollers (UA) of the embossing group (U) are also associated with bonding rolls (M) which exert, by means of their respective actuators (MA), a radial thrust (C) of a predetermined value on the same stamping rollers (UA); and - the thrust (T) exerted by the counter roller (UG) of the embossing group (U) on each stamping roller (UA) is contained in a plane (PT) passing through the rotation axis (X) of each stamping roller (UA) and is inclined at an angle (a) with respect to a plane (PA) passing through said same rotation axis (X) and the longitudinal axis (Y) of the bonding roll (M), thereby generating a counter thrust (TX) directed in the opposite direction to the radial thrust (C) exerted by the bonding roll (M) on it; The bonding roll (M) is made of steel.

[0031] It will also be apparent from the above that, although this is not necessary, devices supplying further plies can also be configured as embossing groups.

[0032] Preferably, the angle (a) is between 100° and 120°. More preferably, the angle (a) is between 105° and 115°, and even more preferably between 108° and 112°. In a device configuration that is considered particularly efficient, the angle (a) is between 109° and 111°. The optimum value for the angle (a) is 110°.

[0033] In a possible configuration of the above-described device, the position of the counter roller (UG) relative to the stamping roller (UA) can be changed. For example, as shown in the diagram in Fig. 2A, the counter roller (UG) is attached to an arm (B) hinged to the structure (S) and pivoted on the same axis (X) as the stamping roller (UA) and controlled in its rotation (Z) by an electric jack (ME), thus allowing the aforementioned angle (a) to be changed. The dotted arrow in Fig. 2B represents the rotation (Z). Since Figs. 2A and 2B are side views, only one arm (B) is visible.

[0034] However, the bonding roll (M) may have a superficial crowning.

[0035] However, in practice, details of implementation may vary within the range of equivalents with respect to the individual elements described and illustrated without departing from the scope of protection provided by this patent according to the appended claims.

Claims

1. an embossing group (U) for embossing each ply (P2) associated with at least one feeding device for feeding a further ply (P1); a group (G) for distributing a liquid that promotes bonding of the plies to one another; An embossing device (EU) comprising: The embossing group (U) comprises a steel stamping roller (UA) and a rubber counter roller (UG), the rubber counter rollers (UG) of the embossing groups (U) exert a predetermined thrust (T) on the respective imprinting rollers (UA) by means of corresponding actuators (AG); The marking rollers (UA) of the embossing group (U) are also associated with bonding rolls (M) which exert a radial thrust (C) of a predetermined value on the same marking rollers (UA) by means of their respective actuators (MA), the thrust (T) exerted by the counter roller (UG) of the embossing group (U) on each of the impression rollers (UA) is contained in a plane (PT) passing through the rotation axis (X) of each of the impression rollers (UA) and is inclined at a predetermined angle (a) with respect to a plane (PA) passing through the same rotation axis (X) and also passing through the longitudinal axis (Y) of the bonding roll (M), thereby generating a counter thrust (TX) directed in the opposite direction to the radial thrust (C) exerted by the bonding roll (M) on the impression roller (UA); and The embossing device, wherein the bonding roll (M) is made of steel.

2. 2. The embossing device according to claim 1, wherein the angle (a) is between 110° and 120°.

3. 2. The embossing device according to claim 1, wherein the angle (a) is between 105° and 115°.

4. 2. The embossing device according to claim 1, wherein the angle (a) is between 108° and 112°.

5. 2. The embossing device according to claim 1, wherein the angle (a) is between 109° and 111°.

6. 2. The embossing device of claim 1, wherein the angle (a) is 110 degrees.

7. 2. The embossing device of claim 1, wherein the angle (a) is adjustable.

8. 2. An embossing device according to claim 1, wherein the device for supplying the further ply (P1) is also an embossing group (L).

9. 2. An embossing device according to claim 1, wherein the moduli of the counter thrust (TX) and the thrust (C) are of the same order of magnitude.

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