The present invention generally relates to the field of tissue converting machines for converting a tissue web, such as a paper web or a nonwoven fabric web, which machines are used for example in the production of napkins. More specifically, the present invention relates to a feeding unit for continuously feeding a two-layer tissue web to a machine of the type identified above.

Feeding units are known for feeding tissue converting machines, which are configured to accommodate a pair of tissue reels (one in use and the other in reserve) and to automatically join the tissue web of the reserve reel to the tissue web of the reel in use when the latter is almost spent, so as to guarantee the continuous feed of the machine with no need to stop the machine to replace the spent tissue reel with a new one. The known feeding units are, however, only able to operate on single-layer tissue webs. An example of feeding unit of this type is disclosed in WO 2005/110903.

WO 2015/071839 discloses a feeding unit for a tissue converting machine arranged to operate with a web of multi-layer tissue. According to this known solution, the tissue layers unwound from a reel are separated from each other by suitable separators upstream of a cutting and joining station where each new tissue layer is joined to a respective tissue layer of the tissue reel to be replaced. Since the tissue layers are separated from each other as they move through the feeding unit, this known solution does not ensure a precise alignment of the tissue layers with each other. It is therefore an object of the present invention to provide a feeding unit for continuously feeding a tissue converting machine which is able to operate on a two-layer tissue web, joining the first layer of the new tissue reel to the first layer of the tissue reel to be replaced and the second layer of the new tissue reel with the second layer of the tissue reel to be replaced, and ensures that the two layers of the tissue web are kept precisely aligned with each other.

This and other objects are fully achieved according to the present invention by a feeding unit having the features set forth in independent claim 1.

Advantageous embodiments of the invention are the subject-matter of the dependent claims, the content of which is to be understood as forming an integral and integrating part of the following description.

In summary, the invention is based on the idea of providing a feeding unit comprising: support means for rotatably supporting a first reel of two-layer tissue web and a second reel of two-layer tissue web about respective axes of rotation;

- cutting means for cutting the two layers of the tissue web of one of said first and second reels, namely the reel that is being used, said cutting means being configured to cut the two layers of the tissue web along two cut lines spaced from each other in the longitudinal direction of the web;

joining means for joining each of the two layers of the tissue web of the other of said first and second reels, namely the new reel, to a respective layer of the tissue web of the reel in use; and

tissue web accumulation means for accumulating a given amount of tissue web downstream of the cutting means and the joining means so as to ensure that the machine is fed with the tissue web while the portion of tissue web on which the cutting means and the joining means act is kept temporarily still to allow cutting of the two layers of the tissue web in use and joining of these layers with the two layers of the new tissue web, wherein said cutting means comprise a first cutting member for cutting the inner layer of the tissue web in use and a pair of second cutting members which are placed on opposite sides of the first cutting member with respect to a plane parallel to the tissue web in use and are arranged to cut the outer layer of the tissue web in use, said second cutting members being positioned at a distance from said first cutting member in the longitudinal direction of the tissue web in use,

wherein said first cutting member is placed downstream of said second cutting members with respect to the feeding direction of the tissue web in use, and

wherein each of said second cutting members comprises a separating element adapted to be inserted between the two layers of the tissue web in use to keep said layers detached from each other along a side edge of the tissue web in use. A feeding unit thus configured is therefore able to continuously feed the machine with a two-layer tissue web, joining each of the two layers of the new tissue web to the respective layer of the tissue web in use when the latter is almost spent, with no need to stop operation of the machine. Moreover, since the two layers of the tissue web in use are always kept attached to each other, except when the tissue web in use is cut by the cutting means (as they are detached from each other by means of the separating element of the second cutting member), it is ensured that the two layers of the tissue web are always precisely aligned to each other. Further characteristics and advantages of the present invention will become more apparent from the following detailed description, given purely by way of non-limiting example with reference to the accompanying drawings, where:

Figure 1 is a perspective view of a feeding unit according to an embodiment of the present invention;

Figure 2 is a further perspective view of the feeding unit of Figure 1, where the feeding unit is sectioned through a vertical cross-section plane perpendicular to the axes of rotation of the reels;

Figures 3 and 4 are a front view and a rear view of the feeding unit of Figure 1, respectively;

Figure 5 shows, on enlarged scale, the detail A of Figure 2; and

Figure 6 shows in sequence the operations of cutting of the two layers of the tissue web in use and joining of the same with the two layers of a new tissue web in a feeding unit according to the present invention. Referring first to Figures 1 to 4, a feeding unit for feeding a tissue converting machine for converting a two-layer tissue web (such as a two-layer paper web) is generally indicated at 10.

Although reference is made in the following description to a two-layer tissue, the feeding unit of the invention is also capable of operating on tissue webs having more than two layers. The following description is thus also applicable to the case of a tissue web having more than two layers, since each of the two layers mentioned below may be in turn formed of two or more layers. The invention is not therefore to be intended as limited to the use of a two-layer tissue web, but also includes the case where the tissue web with which the machine is fed by the feeding unit of the invention is a tissue web having more than two layers.

The feeding unit 10 is arranged to unroll the two-layer tissue web (hereinafter simply referred to as web) from a reel and to eject it from an output O, facing the machine (which is of a known type and is therefore not shown in the drawings), with a given linear speed, for example equal to 600 m/min. The feeding unit 10 is further arranged to feed the machine continuously, i.e. without having to stop the machine when it is necessary to replace the spent reel with a new reel. To this end, as will be explained in more detail in the remaining part of the description, the feeding unit 10 contains a pair of reels, indicated at Rl and R2, respectively, one of which is in use while the other serves to replace the first one when the latter is almost spent. In the example shown in the drawings, the reel in use is the reel Rl, which is facing the side opposite to the output O, while the reel R2, placed on the same side as the output O, is intended to replace the reel Rl when the latter is almost spent. According to the invention, the transition from one reel to the other is achieved by joining the web (indicated at W2) of the new reel R2 to the web (indicated at Wl) of the reel Rl in use, after cutting the latter, in particular by joining a first layer Ll_2 of the new web W2 to a first layer Ll_l of the web Wl in use and joining the other layer L2_2 of the new web W2 to the other layer L2_l of the web Wl in use.

The feeding unit 10 comprises first of all a pair of support uprights 12 for supporting each a respective reel Rl, R2 in a freely rotatable manner about its axis. The axes of the two reels Rl and R2, indicated at xl and x2, respectively, are oriented horizontally and parallel to each other. In addition, the axes xl and x2 are oriented perpendicularly to the direction along which the web Wl in use leaves the feeding unit 10 through the output O. Each reel Rl, R2 is associated with an actuation device 14 arranged to drive the reel for rotation about its axis xl, x2 to cause the web Wl, W2 to unroll from that reel. In the proposed embodiment, each actuation device 14 controls the rotation of the respective reel Rl, R2 by means of an endless belt 16 which is wound around a set of pulleys 18 (one of which acts as a driving pulley) and is held in contact against the side surface of the reel Rl, R2 with a given force of contact.

The web Wl unrolled from the reel Rl is conveyed to the output O of the feeding unit along a given path defined by a plurality of rollers 20 oriented with the respective axes of rotation parallel to the axes of rotation xl and x2 of the two reels Rl and R2. The rollers 20 are supported by a support frame 22, which has, for example, a portal-like structure comprising a first upright 24 and a second upright 26. The first and second reels Rl and R2 are arranged on opposite sides of the first upright 24, with the second reel R2 interposed between the first upright 24 and the second upright 26.

On the first upright 24 there is provided a cutting and joining unit, generally indicated at 28, which is arranged to cut the two layers Ll_l and L2_l of the web Wl in use and to join each of the two layers Ll_2 and L2_2 of the new web W2 to a respective layer of the first web Wl. On the second upright 26 there is provided a web accumulation unit, generally indicated at 30, which is arranged to accumulate, before the cutting and joining unit 28 performs the operations of cutting the web Wl in use and joining the new web W2 with the first web Wl, a given quantity of web downstream of the cutting and joining unit 28 to ensure that the machine continues to be fed with the web Wl while the portion of web Wl on which the cutting and joining unit 28 acts is held temporarily stationary to allow the cutting and joining operations to be carried out. The accumulation unit 30 is of per-se-known type and will therefore not be described in further detail.

Referring also to Figures 5 and 6, the web in use (in the illustrated example, the web Wl) moves through the cutting and joining device 28 along a substantially vertical direction, or a direction slightly inclined with respect to the vertical one. The cutting and joining device 28 comprises first of all a first cutting member 32, which is movable transversely (under control of suitable actuation means, which are of per-se-known type and are not shown in the drawings) with respect to the web Wl in use to cut one of the two layers of this web, namely the layer Ll_l facing the inside of the cutting and joining device 28 (hereinafter referred to simply as inner layer). The first cutting member 32 is, for example, carried by a vertical arm 36 slidably mounted on a guide profile 38 extending transversely to the web Wl (hence parallel to the axes xl and x2 of the two reels Rl and R2). According to an embodiment, the first cutting member 32 comprises a wedge-shaped central element 34 having a pair of surfaces 34a inclined to one another and converging toward a substantially vertical edge 34b. A circular blade 39 (Figure 6), or similar cutting member, is rotatably mounted about a vertical axis of rotation on the central element 34. The rotation of the blade 39 about its axis is controlled by means of suitable actuation means, for example by means of an electric motor 41 (Figure 5). The first cutting member 32 further comprises a pair of wedge-shaped side elements 40_1 and 40_2, arranged on opposite sides with respect to the central element 34. Each side element 40_1 and 40_2 cooperates with the surface 34a of the central element 34 facing thereto to guide the inner layer Ll_l of the web Wl in use towards the blade 39 with a given orientation with respect to the blade itself.

The first cutting member 32 is positioned with respect to the web portion passing through the cutting and joining device 28 so that it may enter with one of the two side elements 40_1 and 40_2 between the two layers Ll_l and L2_l to cut the inner layer Ll_l. In the illustrated embodiment, in which the web in use is the web Wl that is unrolled from the reel Rl, the transverse movement of the first cutting member 32 causes the first side element 40_1 to pass between the two layers Ll_l and L2_l of the web, thus causing the inner layer Ll_l, which is placed between the first side element 40_1 and the central element 34, to be cut. Naturally, when on the contrary the web in use is the web W2 that is unrolled from the reel R2, the transverse movement of the first cutting member 32 causes the second side element 40_2 to pass between the two layers Ll_2 and L2_2 of the web, thereby causing the inner layer L2_2, which is placed between the second side element 40_2 and the central element 34, to be cut.

The cutting and joining device 28 further comprises a pair of second cutting members 42 (only one of which is shown in the drawings, and specifically in Figure 6), which are arranged on opposite sides of the first cutting member 32 with respect to a plane parallel to the web Wl in use and are both movable (under the control of suitable actuation means, which are of per-se-known type and are not shown in the drawings) transversely with respect to the web Wl in use to cut the other layer (i.e. the layer L2_l) of such web, i.e. to cut the layer facing the outside of the cutting and joining device 28 (hereinafter referred to as outer layer).

As can be seen by observing Figure 6, the second cutting members 42 are also positioned vertically spaced with respect to the first cutting member 32 so as to cut the outer layer L2_l of the web Wl in use along a cut line that is vertically spaced (therefore spaced along the longitudinal direction of the web Wl) from the cut line along which the first cutting member 32 cuts the inner layer Ll_l. More specifically, the first cutting member 32 is positioned above the second cutting members 42, so that the inner layer Ll_l of the web Wl in use is cut along a cut line positioned above the cut line along which the outer layer L2_l is cut (or, more generally, positioned downstream of this cut line, with respect to the feeding direction of the web Wl).

Still with reference to Figure 6, according to an embodiment of the invention each second cutting member 42 comprises a circular blade 43, or similar cutting element, which is rotatably mounted about a vertical axis of rotation and is controllable in rotation about said axis by means of suitable actuation means, for example by means of an electric motor 45.

Each second cutting member 42 further comprises a separating element 47, made for example as a tab, having the function of separating the two layers Ll_l and L2_l of the web Wl in use. The second cutting member 42 associated with the web Wl in use is normally kept in a position such that the separating element 47 slightly penetrates (e.g., one or two centimeters) inside the web Wl between the two layers Ll_l and L2_l so as to keep the two layers detached from each other along the side edge of the web Wl. To summarize, therefore, both when the web in use is the web Wl that is being unrolled from the first reel Rl and when the web in use is the web W2 that is being unrolled from the second reel R2, the cutting and joining device 28 is arranged to cut the two layers of the web in use along cut lines spaced apart from each other in the longitudinal direction of the web, and specifically with the cut line of the inner layer positioned above the cut line of the outer layer. Cutting of the web Wl is preferably carried out by first cutting the outer layer L2_l by means of the second cutting member 42 and then by cutting also the inner layer Ll_l by means of the first cutting member 32. The cutting and joining device 28 is also arranged to join the two layers Ll_l and L2_l of the web in use (in this case the web Wl) once they have been cut by the first cutting member 32 and by the second cutting member 42 in the manner described above, each with a respective layer Ll_2 and L2_2 of the new web (in this case the web W2).

To this end, according to an embodiment of the invention the cutting and joining device 28 further comprises a pair of plates 44_1 and 44_2 which are arranged on opposite sides with respect to the portion of web Wl in use that passes through the cutting and joining device 28 and are each carried by a respective support structure 46_1 and 46_2 mounted on the first upright 24 so as to be able to tilt about a horizontal axis of rotation parallel to the axes xl and x2 between a rest position and a working position. The plate 44_1 and the respective support structure 46_1 are arranged on the same side as the reel Rl, while the plate 44_2 and the respective support structure 46_2 are arranged on the same side as the reel R2. In the normal operating condition, the support structures 46_1 and 46_2 with the respective plates 44_1 and 44_2 are kept in the working position, where they are arranged vertically.

The support structure 46_2 with the respective plate 44_2 is shown in the drawings in the rest position, where it is arranged horizontally or slightly inclined to the horizontal. With the support structure 46_2 and the respective plate 44_2 in that position, the operator positions and locks the leading edges of the two layers Ll_2 and L2_2 of the new web W2 on the plate 44_2 at a distance from each other equal to the distance between the cut lines along which the two layers Ll_l and L2_l of the web Wl in use are cut by the first cutting member 32 and by the second cutting member 42. This operation is performed manually by the operator while the feeding unit 10 is feeding the machine with the web Wl, so that when the web Wl is almost spent the new web W2 is ready to be joined to the web Wl to ensure continuous feeding of the machine. On the leading edges of the two layers Ll_2 and L2_2 of the web W2, on the upwardly facing side, a layer of adhesive 52 (e.g. a double- sided adhesive tape) is applied to allow each layer of said web to be attached to the respective layer of the other web Wl .

Once the spent web Wl has been cut in the manner described above, the two plates 44_1 and 44_2 are urged against each other so as to press the leading edges of the two layers Ll_2 and L2_2 of the new web W2 (on which the adhesive layer 52 is applied) against the end edges of the two layers Ll_l and L2_l of the web Wl and thus join each layer of the new web W2 to the respective layer of the web Wl. To this end, each support structure 46_1, 46_2 comprises linear guides 48 for guiding the respective plate 44_1, 44_2 in the translational movement in a direction perpendicular to its plane and a linear actuator 50, made for example as a pneumatic cylinder, for controlling the movement of the respective plate 44_1, 44_2 in a direction perpendicular to its plane. The cutting and joining operation is therefore carried out by the cutting and joining device 28 as follows, assuming that the web in use is the web Wl that is being unrolled from the reel Rl.

Before the web Wl in use is spent, the new web W2 is prepared to be joined to the web Wl. To this end, the operator places on the plate 44_2 of the support structure 46_2 (with the latter placed in the rest position) the two layers Ll_2 and L2_2 of the new web W2 with the respective leading edges spaced from each other at a distance equal to the distance between the cut lines along which the first cutting member 32 and the second cutting member 42 are arranged to cut the two layers Ll_l and L2_l of the web Wl in use, in particular with the inner layer Ll_2 of the new web W2 shorter than the outer layer L2_2. The operator also applies a layer of adhesive 52 near the leading edges of both the layers Ll_2 and L2_2 of the new web W2. When the web Wl in use is nearly spent, the accumulation unit 30 is controlled to accumulate a given amount of web downstream of the cutting and joining unit 28. Thereafter, the cutting and joining unit 28 is controlled to perform in succession the operations of cutting the web Wl in use and joining the new web W2 to the web Wl. In this connection, the two layers Ll_l and L2_l of the web Wl in use (which to this end is temporarily stopped) are cut by the first cutting member 32 and by the second cutting member 42 along respective cut lines spaced apart from one another and then the plate 44_1 of the support structure 46_1 is pushed against the plate 44_2 of the other support structure 46_2 so as to press the final end portion of each of the two layers Ll_l and L2_l of the web Wl in use against the leading end portion of the respective layer Ll_2 and L2_2 of the new web W2, thereby making these portions adhere to each other due to the adhesive layer 52 previously applied on the new web W2. At this point, the feeding unit 10 is ready to feed the machine with the new web W2. As can be seen from the above description, the transition from the condition where the machine is being fed with the web Wl to the condition where the machine is being fed with the new web W2 occurs with no interruptions in the feeding of the machine, which undoubtedly leads to an increase in the productivity of the machine.

Naturally, the principle of the invention remaining unchanged, the embodiments and constructional details may be greatly varied with respect to those described and illustrated here purely by way of a non-limiting example, without thereby departing from the scope of the invention as defined in the accompanying claims.