Embossing unit for processing paper roll

Abstract

An embossing unit comprises a steel carving roller (UA) and a rubber counter roller (UG), the rubber counter roller (UG) exerting a thrust (T) with a predetermined value on the carving roller (UA) by means of a corresponding actuator (AG), and a combination roller (M) associated with the carving roller exerts a radial thrust (C) with a predetermined value on the same carving roller (UA) by means of a corresponding actuator. According to the invention, the thrust (T) exerted by the mating roller on the engraving roller (UA) is contained in a plane (PT) which passes through the axis of rotation (X) of the respective engraving roller (UA) and which is inclined at a predetermined angle (a) with respect to the plane (PA) which passes through the same axis of rotation (X) and also through the axis (Y) of the joining roller, thereby generating a mating thrust (TX) opposite the thrust (C). The coupling roller (M) is made of steel.

Description

Detailed implementation mode

[0001] The present invention relates to an embossing unit for processing paper rolls.

[0002] More specifically, the present invention relates to a unit of this type, which includes two operating groups, at least one of which includes a steel engraving roller and a rubber mating roller, which cooperate with each other to provide embossing of the corresponding paper layer, and the other operating group can also be configured as an embossing group or a group for feeding non-embossed layers. These two layers can be joined together by gluing. The final joining of these layers is facilitated by using a bonding roller with a rubberized surface, which applies pressure to the same layers downstream of the operating group. This type of operating unit is usually used in so-called paper conversion factories, where products such as toilet paper rolls, kitchen paper rolls, etc. are produced, and more generally products obtained by paper conversion.

[0003] Since the disadvantage of using an operating unit constructed in this way stems from the need to apply a relatively large pressure to the bonding roller to achieve effective mutual connection of the layers, which in most cases determines re-embossing, which changes the embossing provided by the two embossing groups and requires a large amount of energy compared to current production requirements. In addition, since the bonding roller is dragged and rotated by the engraving roller acting on it, it is difficult to control the rotation of the bonding roller.

[0004] US2013 / 0099417A1 discloses an embossing unit for processing web-like paper materials, which includes: an embossing roller; a pressure roller coated with an elastic embossing material and cooperating with the embossing roller; and at least one actuator for pushing the embossing roller and the pressure roller against each other. In this embossing unit, the pressure roller structure covered with an elastic yielding material is designed and controlled such that re-embossing of the paper material is allowed when required by planned production.

[0005] The object of the present invention is to provide an embossing unit in which a bonding roller can be used, which avoids re-embossing the layers. Another object of the present invention is to provide an embossing unit in which the pressure applied to the paper layer can be reduced. Another object of the present invention is to provide an embossing unit in which the rotation of the bonding roller can be controlled.

[0006] According to the present invention, this result has been achieved by adopting the idea of providing a machine with the features indicated in claim 1. Other features of the present invention are the subject matter of the dependent claims.

[0007] Due to the following description and drawings, each person skilled in the art will more and better understand other advantages and features of the present invention. These description and drawings are provided by way of example and are not considered restrictive. In the drawings:

[0008] - Figure 1 is a schematic side view of a machine according to the invention in a possible operating configuration;

[0009] - Figure 2A is also a schematic side view of a machine according to the invention, in which some parts are not shown to better highlight other parts;

[0010] - Figure 2B shows Figure 2A details;

[0011] - Figure 3 schematically shows the correct contact between the engraving roller and the bonding roller of the second embossing group;

[0012] - Figure 4 schematically shows the incorrect contact between the engraving roller and the bonding roller of the second embossing group;

[0013] - Figure 5 schematically shows the forces acting on the second embossing group in an embossing unit having the configuration as Figure 1 shown;

[0014] - Figure 6 A side view schematically representing the undeformed engraving roller (UA) using solid lines and the deformation caused by the thrust applied by the corresponding mating roller using dashed lines;

[0015] - Figure 7 and Figure 8 schematically represent two other possible operating configurations of a machine according to the invention.

[0016] Simplified to its basic structure and with reference to the drawings, with respect to possible operating configurations, the embossing unit (EU) according to the invention comprises, for example:

[0017] - A first embossing group (L);

[0018] - A second embossing group (U);

[0019] - A gluing group (G);

[0020] - A structure (S) configured to support the gluing group (G), the first embossing group (L) and the second embossing group (U).

[0021] Referring to Figure 1 the example shown, the first embossing group (L) is arranged below the second embossing group (U).

[0022] Each of said embossing groups (L, U) includes a steel engraving roller (LA, UA) and a corresponding rubber counter-roller (LG, UG). Said rollers (LA, LG, UA, UG) are horizontally arranged between two opposite walls of the structure (S). Preferably, the rollers (LA, LG, UA, UG) are detachably mounted on the structure (S) by means of detachable connection members known per se. For example, the rollers (LA, LG, UA, UG) can be connected to the structure (S) by means of detachable or openable collar parts acting on the ends of the rollers themselves. Referring Figure 1 to the arrangement shown, the engraving roller (LA) of the first embossing group (L) is located above the corresponding rubber counter-roller (LG), while the engraving roller (UA) of the second embossing group (L) is located below the corresponding rubber counter-roller (UG).

[0023] The embossing unit (EU) further includes a combining roller (M), which is also supported by the structure (S) and is oriented such that its corresponding axis is parallel to the axes of the rollers (LA, LG, UA, UG). The combining roller (M) is located in front of the engraving roller (UA) of the second embossing group (U) with respect to the direction followed by the paper layers (P1, P2). The gluing unit (G) is in a relative position with respect to the combining roller (M), i.e., it is behind the engraving roller (UA) of the second embossing group (U). The outer surface of the combining roller (M) is smooth, i.e., not engraved.

[0024] For example, the gluing group (G) includes a pot (GT) containing glue and a first horizontal roller (HR), which picks up the glue from the pot (GT) and transfers it by contact to a second horizontal roller (HG), which in turn transfers the glue to the paper layer (P2), as further described below. In a known manner, the rollers (HR, HG) of the gluing group are controlled by corresponding electric motors (not visible in the drawings) to rotate around their respective axes at a predetermined speed to draw the glue from the pot (GT) and distribute it on the paper layer (P2). Each rubber counter-roller (LG, UG) is pushed against the corresponding engraving roller (LA, UA) by means of a corresponding actuator (AL, AG) acting on the ends of the same counter-roller.

[0025] In the operating mode, the embossing groups (L, U) emboss the respective layers (P1, P2) by means of methods known per se: the layer (P1) passes between the rollers (LG, LA) of the first embossing group (L), and the other layer (P2) passes between the rollers (UG, LG) of the second embossing group (U). Furthermore, the second layer (P2) comes into contact with the second roller (HG) of the gluing unit (G), and the two layers (P1, P2) pass between the engraving rollers (LA, UA). Thus, the layers (P1, P2) are embossed and glued together, producing a web of paper material composed of the embossed and glued layers (P1, P2). The web of paper material (W) exits from the nip formed by the engraving roller (UA) and the combining roller (M).

[0026] According to the invention, the rubber counter-roller (UG) of the second embossing group (U) is arranged to exert a thrust (T) that lies in a plane (PT) passing through the axis of rotation (X) of the corresponding engraving roller (UA) and is inclined at a predetermined angle (a) with respect to a plane passing through the same axis of rotation (X) and also through the longitudinal axis (Y) of the combining roller (M). In practice, referring to the schematic diagram in Figure 1 , the rubber counter-roller (UG) of the second embossing group (U) is in a backward position with respect to the corresponding engraving roller (UA) relative to the direction of origin of the corresponding web (P2).

[0027] The combining roller (M) is a steel roller that is also pushed towards the engraving roller (UA) of the second embossing group (U) by means of a respective actuator (AM). Figure 5 The schematic diagram in Figure 5 shows the thrust (C) exerted by the combining roller (M) on the engraving roller (UA) of the second embossing group (U). In addition to the horizontal (TX) and vertical (TY) components of the thrust (T), Figure 3 the schematic diagram in Figure 4As shown, the intervention of the combining roller will be ineffective. In addition, the contact between the roller (HG) and the engraving roller of the second embossing group (U) is optimized, and it is believed that there may also be advantages in terms of higher energy efficiency of the system.

[0028] Figure 6 The undeformed engraving roller (UA) is represented by a solid line, and the deformation caused by the thrust (T) exerted by the corresponding mating roller is represented by a dashed line. The reference numeral "d" represents the radial deflection of the roller (UA).

[0029] If necessary, the combining roller (M) can also be a crowned roller.

[0030] In the machine according to the present invention, the following features are combined synergistically:

[0031] - The diagonally oriented thrust (T), i.e., oriented along the aforementioned plane (PT);

[0032] - The combining roller (M) made of steel.

[0033] It is understood that the previously mentioned planes (PT) and (PA) are geometric planes, not material planes.

[0034] The rotation of the combining roller (M) is controlled by a corresponding electric motor (schematically represented by the dashed circle 1M in Figure 1 .

[0035] In an alternative operating configuration, the first operating group (L) can be replaced by a device for feeding the unembossed web (P1). In the Figure 8 example, this feeding device includes a roller (RA) for guiding the web (P1) into the nip formed by the engraving roller (UA) of the group (U) and the combining roller (M).

[0036] In another possible operating configuration, as shown in the schematic example of Figure 7 , in addition to the layers (P1) and (P2), another layer (P3) is fed by means of a roller (RB) which guides the other layer (P3) in the nip between the distribution roller (HG) of the gluing group (G) and the engraving roller (UA). In this case, the machine produces a web (W) comprising the layers (P1), (P2) and (P3).

[0037] Therefore, the machine according to the present invention can be constructed according to various arrangements depending on the characteristics required to discharge the web (W) from the machine.

[0038] The pot (GT) can contain water instead of glue and may be ink.

[0039] The substance contained in the pot (GT) favors the formation of the bonding of the layers of the web (W).

[0040] The passage of the layers (P1, P2; P1, P2, P3) in the nip formed by the roller (UA) and the bonding roller (M) determines the final bonding of the same layers.

[0041] The steel bonding roller (M) avoids the re-embossing of the layers, and instead the use of a rubber-coated bonding roller can occur, which is elastically yielding in nature. In other words, compared to rubber, that is, compared to the elastically yielding material covered by the bonding rollers of the prior art, steel is more rigid, which prevents further embossing of the paper layers by the linear pressure in the nip formed by the roller (UA) and the bonding roller (M), and the magnitude of this linear pressure is typically between 12 kg / cm and 25 kg / cm.

[0042] It can be seen from the foregoing description that the embossing unit (EU) according to the present invention includes: an embossing group (U) for embossing a corresponding layer (P2), which corresponding layer (P2) is associated with at least one feeding device for another layer (P1), and a group (G) for dispensing a liquid that favors the mutual bonding of the said layers, wherein the embossing group (U) includes a steel engraving roller (UA) and a rubber mating roller (UG), wherein the rubber mating roller (UG) of the embossing group (U) applies a thrust (T) of a predetermined value on the corresponding engraving roller (UA) by means of a corresponding actuator (AG), wherein the engraving roller (UA) of the embossing group (U) is also associated with a bonding roller (M), which bonding roller (M) applies a radial thrust (C) of a predetermined value on the same engraving roller (UA) by means of a corresponding actuator (MA), and wherein:

[0043] - The thrust (T) applied by the mating roller (UG) of the embossing group (U) on the corresponding engraving roller (UA) is contained in a plane (PT) that passes through the rotation axis (X) of the corresponding engraving roller (UA), and the thrust (T) is inclined by a predetermined angle (a) with respect to a plane (PA) that passes through the same axis (X) and also passes through the longitudinal axis (Y) of the bonding roller (M), thereby generating a mating thrust (TX) that is oriented in the opposite direction to the radial thrust (C) applied thereon by the bonding roller (M);

[0044] - The bonding roller (M) is made of steel.

[0045] It is apparent from the foregoing description that, although not necessary, the device for feeding another layer can also be configured as an embossing group.

[0046] 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 mechanical configuration considered to be particularly effective, the angle (a) is between 109° and 111°. The optimum value of the angle (a) is 110°.

[0047] In a possible configuration of the aforementioned machine, the position of the mating roller (UG) relative to the engraving roller (UA) can be modified. For example, as Figure 2A shown, the mating roller (UG) is mounted on an arm (B) hinged to the structure (S), pivots on the same axis (X) as the engraving roller (U), and is served by an electric jack (ME) that controls its rotation (Z), thereby allowing the aforementioned angle (a) to be modified in this way. Figure 2B The dashed arrow in Figure 2A and Figure 2B indicates the rotation (Z). In

[0048] However, the combining roller (M) can have a superficial crowning.

[0049] However, in practice, for the various elements described and shown, the implementation details can vary in an equivalent manner without departing from the scope of protection provided by this patent according to the appended claims.

Claims

1. An embossing unit (EU), comprising: Embossing group (U) for embossing a corresponding layer (P2), said layer (P2) being associated with at least one feeding device for feeding another layer (P1), and group (G) for distributing a liquid conducive to the binding of the layers to each other, wherein said embossing group (U) comprises a steel engraving roller (UA) and a rubber counter-roller (UG), wherein said rubber counter-roller (UG) of said embossing group (U) applies a thrust (T) of a predetermined value on the corresponding engraving roller (UA) by means of a corresponding actuator (AG), and wherein a binding roller (M) also associated with said engraving roller (UA) of said embossing group (U) applies a radial thrust (C) of a predetermined value on the same said engraving roller (UA) by means of a corresponding actuator (MA), characterized in that: the thrust (T) applied by said counter-roller (UG) of said embossing group (U) on the corresponding said engraving roller (UA) is contained in a plane (T) which passes through the rotation axis (X) of the corresponding said engraving roller (UA), and said thrust (T) is inclined by a predetermined angle (a) with respect to a plane (PA) which passes through the same rotation axis (X) and also through the longitudinal axis (Y) of said binding roller (M), thereby generating a counter-thrust (TX) oriented in the opposite direction with respect to said radial thrust (C), said radial thrust (C) being applied thereon by said binding roller (M); and wherein said binding roller (M) is made of steel.

2. The embossing unit according to claim 1, characterized in that, Said angle (a) is between 110° and 120°.

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

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

5. The embossing unit according to claim 1, characterized in that, Said angle (a) is between 109° and 111°.

6. The embossing unit according to claim 1, wherein, Said angle (a) is equal to 110°.

7. The embossing unit according to claim 1, wherein Said angle is adjustable.

8. The embossing unit according to claim 1, characterized in that, Said feeding device for feeding said another layer (P1) is also an embossing group (L).

9. The embossing unit according to claim 1, characterized in that, Said counter-thrust (TX) and said thrust (C) are of the same order of magnitude in modulus.

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