IT201800002344A1 - INTERLIFTING MACHINE WITH IMPROVED ARRANGEMENT OF COUNTING COMBS - Google Patents

Description

INTERFOLIATING MACHINE WITH IMPROVED ARRANGEMENT OF COUNTING COMBS "

Description

Technical Field

[0001] The invention relates to interleaving machines. More specifically, the invention relates to improvements to mobile counting combs of reciprocating motion combined with the interleaving rollers in order to remove individual stacks of folded sheets from them.

Front Art

[0002] Interleaving machines are commonly used in industry for the production of packs of interleaved sheets. Interleaving machines are for example used for the production of packs of interleaved tissue paper handkerchiefs, or similar tissue paper articles.

[0003] Typically, an interleaving machine comprises counter-rotating interleaving rollers arranged one adjacent to the other and with parallel rotation axes, defining an interleaving groove between them. Sheets produced by cutting a continuous web material are fed alternately to one and the other of said interleaving rollers. Each sheet is folded along a central fold line, thus forming two portions of the sheet. The two sheet portions of each sheet are arranged between two sheet portions of a previous sheet and between two sheet portions of a subsequent sheet, so as to form a stack of interleaved sheets.

[0004] In order to detach each folded sheet from the respective interleaving roller, two series of separator fingers which move in reciprocating motion are associated with the two interleaving rollers. The separating fingers are provided with an alternating oscillation movement around respective oscillation axes at a very high frequency, corresponding to the production speed of the interfolding machine.

The interleaved sheets form stacks, each of which contains a predetermined number of sheets. Stacks formed in succession must be separated from each other and removed from the interleaving rollers, so that a continuous process of formation of stacks can take place.

[0006] In order to achieve higher production speeds it would be advantageous to have very efficient separating combs.

Summary

[0007] According to one aspect, the present invention relates to an interleaving machine comprising a first interleaving roller rotating around a first axis of rotation and a second interleaving roller rotating around a second axis of rotation parallel to the first axis of rotation. The first interleaving roller and the second interleaving roller together form an interleaving groove between them. According to embodiments described here, the interfolding machine further comprises a first pair of counting combs, arranged in front of the interfolding throat, and a second pair of counting combs, arranged in front of the interfolding throat. Each counting comb of said first pair of counting combs and of said second pair of counting combs can be advantageously provided with a movement according to two translation axes, controlled by respective electronically controlled electric motors. The translation axes can be orthogonal to each other and orthogonal to the rotation axes of the interfolding rollers. A first axis can be parallel to a plane containing the rotation axes of the two interfolding rollers. The second axis can be orthogonal to the plane containing the rotation axes of the two interfolding rollers.

[0008] In particularly advantageous embodiments, the first pair of counting combs is movable in a direction orthogonal to a plane containing the axes of rotation of the first interleaving roller and of the second interleaving roller, to support each stack of interleaved sheets in formation and to unload each stack formed on an evacuation conveyor, for example. Using two pairs of counting combs, each stack can be evacuated using a pair of counting combs, while the formation of the next stack can begin on the other pair of counting combs. In some embodiments, an evacuation means, such as an evacuation conveyor, can be disposed under the interfolding throat at a distance therefrom. Each pair of counting combs can be adapted to move along a trajectory under the interfolder groove from the position adjacent to the interfolder groove to a lower unloading position, where each complete stack can be unloaded onto an evacuation conveyor, such as an evacuation belt, or similar.

[0009] According to a further aspect, the present invention relates to a method for producing stacks of interleaved sheets, comprising the following steps:

- feeding a continuous flow of interfolded sheets from an interfolding groove formed between a first interfolder roller and a second interfolder roller, rotating around a respective first axis of rotation and a second axis of rotation;

forming a first stack of interleaved sheets on a first pair of counting combs arranged in front of the interfolding groove and close to each other, while said first pair of counting combs moves gradually away from the interfolding groove; wherein the first pair of counting combs is gradually moved away from the interfolding throat while the first stack of interfolded sheets grows;

- upon completion of the first stack of interleaved sheets, move the first pair of counting combs towards an unloading position, where the first stack of interleaved sheets is unloaded from the first pair of counting combs by moving said first pair of counting combs away from the one from the other; and bring a second pair of counting combs close to each other in a position close to the interfolding throat;

- starting the formation of a second stack of interleaved sheets on the second pair of counting combs, while the first pair of counting combs moves again from the unloading position to a waiting position near the interleaving groove.

[0010] According to a still further aspect, the present invention relates to a method for producing stacks of interleaved sheets, comprising the following steps:

- feeding a continuous flow of interleaved sheets from an interleaving groove formed between a first interleaving roller and a second interleaving roller, rotating around a respective first axis of rotation and a respective second axis of rotation;

- forming a first stack of interleaved sheets on a first pair of counting combs arranged in front of the interleaving throat and close to each other, while said first pair of counting combs gradually moves away from the interleaving throat; wherein the first pair of counting combs is gradually moved away from the interfolding throat while the first stack of interfolded sheets grows;

- transferring the first stack of interleaved sheets onto a second pair of counting combs by spacing the counting combs of said first pair of counting combs;

- upon completion of the first stack of interleaved sheets, moving the second pair of counting combs away from the interleaving groove towards an unloading position; move the first pair of counting combs bringing them closer to each other; and starting the formation of a second stack of interleaved sheets on the first pair of counting combs.

[0011] Further characteristics and advantageous embodiments of the invention are defined in the claims and described below, with reference to the attached drawings.

Brief description of the drawings

[0012] A more complete understanding of the illustrated embodiments of the invention and the many advantages achieved will be obtained when it is better understood with reference to the detailed description that follows, in combination with the attached drawings, in which: the

Fig.1 illustrates a schematic front view of an interleaving machine according to the invention; there

Fig.2 illustrates an enlargement of a portion of Fig.1; there

Fig.3 shows a side view along the line III-III of Fig.2; the

Figs.4A-4C illustrate a sequence of operation in a first embodiment; the

Figs 5A-5C illustrate a sequence of operation in a second embodiment; there

Fig.6 shows a view along the line VI-VI of Fig.2; there

Fig.7 shows a section along the line VII-VII of Fig.6; the

Figs.8A, 8B show views along the line VIII-VIII of Fig.7; there

Fig.9 illustrates a pack of interleaved sheets.

Detailed description

[0013] Fig.1 illustrates a front view of an interfolding machine according to the invention. The interfolding machine 1 comprises a first feed path for a first continuous web material N1 of tissue paper and a second feed path for a second continuous web material N2 of tissue paper. A first rotating cutting roller 3 is arranged along the first path, which is provided with angularly spaced blades 3A. The blades 3A cooperate with a first stationary counter-blade 4. A second rotating cutting roller 5 is arranged along the second path, which is provided with angularly spaced blades 5A. The blades 5A cooperate with a second stationary counter-blade 6. The first cutting roller 3 rotates around a first rotation axis 3B and the second roller 5 rotates around the second rotation axis 5B.

[0014] The first cutting roller 3 is also provided with suction ports 3C along its cylindrical surface. The second cutting roller 5 is in turn provided with suction ports 5C along its cylindrical surface. The suction ports 3C, 5C are adapted to retain on the surface of the respective cutting rollers 3, 5 the sheets obtained by cutting the first and second continuous web material N1, N2, and to transfer said sheets from the cutting rollers 3, 5 to interleaving rollers 9, 11.

[0015] The interfolding rollers 9, 11 rotate around respective rotation axes 9A, 11A, parallel to each other and parallel to the rotation axes of the cutting rollers 3, 5. The two interfolding rollers 9, 11 form a Interleaving throat 13. Each interleaving roller 9, 11 is provided with respective folding members 15, 17. The folding members 15, 17 can provide suction means, or mechanical gripping means or both. Interleaving rolls and folding members are known to those skilled in the art and are not described in detail.

[0016] Each continuous web material N1, N2 is guided around the respective rotating cutting roller 3, 5 and is fed between the cutting roller 3, 5 and the stationary counter blade 4, 6. The cooperation of the rotating blades 3A with the stationary counter blade 4 cuts the continuous web material N1 into single sheets, which are then transferred from the first cutting roller 3 to the first interfolding roller 9. Similarly, the continuous web material N2 is guided around the second cutting roller 5 and cut in sheets through the cooperation of the rotating blades 5A with the stationary counter-blade 6. The single sheets are then transferred from the second cutting roller 5 to the second interfolding roller 11.

[0017] A first series of separator fingers 21 is associated with the first interfolding roller 9. The first series of separator fingers 21 is better shown in Figs.6 and 7. The first interfolder roller 9 is provided with a plurality of annular grooves 9G. In the example shown in Fig.6 there are seven annular grooves 9G and seven separator fingers 21 forming the first series of separator fingers. Each separator finger 21 cooperates with a respective annular groove 9G, with which the first interfolder roller 9 is provided.

[0018] A second series of separating fingers 21 is associated with the second interleaving roller 11. The second series of separating fingers 21 is better shown in Figs.6 and 7. The second interfolding roller 11 is provided with a plurality of annular grooves 11G. In the example shown in Fig.6 there are seven annular grooves 11G and seven separator fingers 23 forming the first series of separator fingers. Each separator finger 23 cooperates with a respective annular groove 11G, with which the second interfolder roller 11 is provided.

A different number of separator fingers and grooves can be provided.

[0020] The annular grooves 9G and 11G provide annular spaces which protrude inside the cylindrical surfaces of the first interfolder roller 9 and of the second interfolder roller 11. As shown in Fig.7, each separator finger 21 can protrude into the respective annular groove 9G inside the cylindrical surface of the interleaving roller 9. Similarly, each separator finger 23 can protrude in the respective annular groove 11G inside the cylindrical surface of the interleaving roller 11.

[0021] The first set of separator fingers 21 are operated by a first actuation mechanism 25, which will be described in greater detail below. The first actuation mechanism 25 drives in an alternating oscillating movement the first series of separator fingers 21 around a first axis of oscillation 21A, parallel to the axis of rotation 9A of the first interleaving roller 9. As shown in Fig. 7, the oscillation axis 21A can be arranged on the cylindrical surface of the first interfolding roller 9 or inside said cylindrical surface. Figure 7 shows the two terminal positions of the first series of separator fingers 21 which oscillate in reciprocating motion. In the first position, shown in broken lines, the distal ends (i.e. the free ends opposite the axis of oscillation 23A) of the first separator fingers 21 are arranged at least partially inside the annular grooves 9G. In the second position, shown in solid lines, the distal ends of the first separator fingers 21 are positioned outside the cylindrical surface of the first interfolder roller 9.

A symmetrical arrangement is provided for the second set of separator fingers 23. The second set of separator fingers 23 is operated by a second actuation mechanism 27, similar or identical to the first actuation mechanism 25. The second actuation mechanism 27 operates the second series of separator fingers 23 in an alternating oscillatory motion around a second oscillation axis 23A, parallel to the rotation axis 11A of the second interfolder roller 11. As shown in Fig. 7, the oscillation axis 23A can be arranged on the cylindrical surface of the second interfolding roller 11, or inside said cylindrical surface. Figure 7 shows the two end positions of the second series of separator fingers 23 oscillating in reciprocating motion. In the first position, shown in solid lines, the distal ends of the second separator fingers 23 are arranged at least partially inside the annular grooves 11G. In the second position, shown in broken lines, the distal ends of the second separator fingers 23 are positioned outside the cylindrical surface of the second interleaving roller 11.

As shown in Fig.7, the oscillation movement of the first set of separator fingers 21 is in phase opposition with respect to the movement of the second set of separator fingers 23, so that when the first set of separator fingers 21 is at inside the annular grooves 9G, the second series of separator fingers 23 is outside the annular grooves 11G and vice versa. The separator fingers 21, 23 separate the folded sheets from the respective interfolding rollers 9, 11 and place the sheets on a first or second pair of counting combs, described below, to form a stack of interfolded sheets on them.

[0024] In preferred embodiments, the first and second series of separator fingers 21, 23 move in synchronism with the folding members 15, 17, so that when a folding member is releasing a folded sheet S1 or S2, the fingers separators 21 or 23 detach or help to detach the folded sheet from the respective interfolding roller 9, 11. The law of optimal motion of the series of separating fingers 21, 23 can be obtained using a respective desmodromic cam (to be described later). The desmodromic cam can be mounted with the correct phase with respect to the interleaving rollers 9, 11.

[0025] The operation of the interfolding machine 1 is generally known in the art and does not require a detailed description. The cooperation of the two interleaving rollers 9, 11 and of the series of separating fingers 21, 23 produces stacks of interleaved sheets, one of which is schematically shown in Fig.9 and marked with SK. Sheets S1 are fed by the first interleaving roller 9 and sheets S2 are fed by the second interleaving roller 11. Each sheet S1 has a central folding line F1, which divides the sheet S1 into two halves. Each sheet S2 has a central fold line F2, which divides the sheet S2 into two halves. The sheets S1, S2 are interleaved or interleaved, in the sense that each half portion of a sheet S1 is arranged between two half portions of a sheet S2 and vice versa. Between two half portions of each sheet S2 are arranged half portions of two consecutive sheets S1. Similarly, half portions of two consecutive sheets S2 are positioned between two half portions of each sheet S1. In this configuration, a folded sheet contains the tail end of the previous sheet and the head end of the next sheet, thus forming an SK stack of interleaved sheets.

[0026] Each first separator finger 21 is articulated in an oscillating way to a respective stationary arm 29. The stationary arms 29 are integrally supported by a stationary frame 31, which can also support the first interfolder roller 9 and the second interfolder roller 11. Similarly , each second separator finger 23 is articulated in an oscillating manner to a respective stationary arm 33. The stationary arms 33 are integrally supported by the stationary frame 31.

[0027] The stationary arms 29 and the stationary arms 33 extend from the stationary frame 31 in front of the respective interfolding rollers 9, 11, on the opposite side with respect to the arrival of the sheets in the interfolding groove 13. The stationary arms 29 and 33 protrude from the frame stationary 31 towards the interfolding groove 13. As better visible in Fig.7, in this embodiment each stationary arm 29 extends towards the interfolding groove beyond the axis of rotation 9A of the first interfolder roller 9. Similarly, each stationary arm 33 it extends from the stationary frame 31 towards the interfolding groove 13 beyond the axis of rotation 11A.

[0028] As shown in Fig.7, each stationary arm 29 and each stationary arm 33 can have a proximal end constrained to the stationary frame 31 and a distal end extending towards the cylindrical surface of the respective interfolder roller 9 and 11. Preferably, as shown in Fig.7, the distal end of each stationary arm 29 and 33 projects inside a respective of the first annular grooves 9G and of the second annular grooves 11G.

[0029] The reciprocating oscillating motion of the first series of separator fingers 21 is transmitted by the first actuation mechanism 25 by means of respective connecting rods 35. The reciprocating oscillation motion of the second series of separator fingers 23 is transmitted by the second actuation mechanism 27 for means of respective connecting rods 37.

[0030] The reference number 35A indicates the point of articulation between the connecting rod 35 and the separator finger 21, while the reference number 37A indicates the articulation point between the connecting rod 37 and the separator finger 23.

[0031] The separating fingers 21, 23 and / or the connecting rods 35, 37 can be made of light material, for example aluminum, carbon fiber, plastic or resin, or fiber-reinforced resin, to reduce the mass and therefore the inertia of them.

[0032] The first actuation mechanism 25 comprises a first rotating shaft 39, which is provided with an alternating rotary motion around an axis 39A which develops parallel to the rotation axis 9A of the first interfolder roller 9. The second actuation mechanism 27 similarly comprises a symmetrical rotating shaft 41, which is provided with an alternating rotational motion around an axis 41A which is parallel to the axis of rotation 11A of the second interfolding roller 11.

[0033] As better illustrated in Fig.7, each connecting rod 35 is mechanically coupled to the first rotating shaft 39 by means of a respective crank 43; the reference number 43A indicates the point of articulation between the crank 43 and the connecting rod 35. In a symmetrical manner, each connecting rod 37 is mechanically coupled to the second rotating shaft 41 by means of a respective crank 45; the reference number 45A indicates the point of articulation between the crank 45 and the connecting rod 35. The reciprocating rotary motion of the first rotating shaft 39 and the reciprocating rotary motion of the second rotating shaft 41 are transmitted through the cranks 43 and 45 and through the connecting rods 35 and 37 to the respective first series of separator fingers 21 and second series of separator fingers 23.

[0034] With reference again to Fig.7, the distance between the axis of rotation 39A (or the axis of rotation 41A) and the pivot point 43A (or 45A) is indicated with L1. The distance between the pivot axis 21A (or 23A) and the pivot point 35A (or 37A) is marked with L2. In preferred embodiments L1 is greater than L2, so that a smaller angular movement of the rotating shafts 39 and 41 is sufficient to cause an appropriate oscillation of the separator fingers 21, 23.

[0035] Both ends of each connecting rod can be articulated to the respective separator fingers and to the respective cranks by means of lubricated cushions, so as to reduce wear and increase the life of the cushions.

[0036] According to the embodiments described here, the reciprocating rotary motion of the first rotating shaft 39 and of the second rotating shaft 41 is imparted by respective desmodromic cams. The desmodromic cam of the first actuation mechanism 25 is shown in Figs 8A, 8B. The desmodromic cam of the second actuation mechanism 27 is symmetrical and is not shown in the drawings. The desmodromic cam which controls the rotary motion of the first rotating shaft 39 is marked with 51 in Figs 8A, 8B. In this embodiment, the desmodromic cam 51 is a dual body cam having a first cam body 51A and a second cam body 51B. The two cam bodies 51A, 51B are rigidly constrained to each other and together form the desmodromic cam 51. The first cam body 51A has a first cam profile 53A and the second cam body 51B has a second cam profile cam 53B. The desmodromic cam 51 cooperates with a rocker 57 constrained to the first rotating shaft 39. The rocker 57 is a double arm, ie an L-shaped arm, having two distal ends. The two distal ends each support a respective roller, wheel or other contact body, which cooperates with one of the cam profiles 53A, 53B. The first contact body and the second contact body are shown at 59A and 59B. The first contact body 59A is in contact with the first cam profile 53A and the second contact body 59B is in contact with the second cam profile 53B.

[0037] A continuous rotary motion according to the arrow f51 of the desmodromic cam 51 is thus converted into an alternating rotary motion (arrow f39) of the rotating shaft 39 around the axis 39A. The rotation of the rotating shaft 39 in both directions (clockwise and counterclockwise) is positively controlled by the two cam profiles 53A, 53B of the desmodromic cam 51. This allows to reach very fast alternating rotational motions and therefore to reach a high production speed of the interleaving machine 1.

[0038] A different desmodromic cam can be provided, for example a cam with a channel, in which a single contact member is arranged. The contact member touches opposite cam profiles formed by opposite side walls of the channel.

The second rotating shaft 41 can be controlled by a symmetrical mechanism, with a desmodromic cam, not shown, which can be designed in the same way as the desmodromic cam shown in Figs.8A, 8B.

[0040] The desmodromic cams can be housed in respective boxes 61, 63 (Fig.6). The rotary motion of the desmodromic cams 51 can be obtained by means of a continuous rotary motion of the respective first and second interfolding rollers 9, 11 as follows. A first toothed wheel 71 can be keyed onto a first shaft 73 of the first interleaving roller 9. A second toothed wheel 75 can be keyed to a second shaft 77 of the second interleaving roller 11. The first toothed wheel 71 and the second toothed wheel 75 mesh with each other so that the first interleaving roller 9 and the second interleaving roller 11 can rotate in opposite directions (arrows f9, f11 in Fig.6) under the control of a motor, schematically shown in 81 in Fig.6 . A respective first pinion 83 meshes with the first toothed wheel 71. The first pinion 83 can be keyed on a first cam shaft 85, on which the desmodromic cam 51 can be keyed (Fig.8A, 8B). Similarly, a second pinion 87 meshes with the second toothed wheel 75 and is keyed on a second cam shaft 89, on which the desmodromic cam is keyed (symmetrical to the cam 51 and not shown) which controls the alternating oscillatory movement of the second rotating shaft. 41.

[0041] Therefore, a first gear train connection 71, 83 transmits the rotational motion from the first interfolder roller 9 to the first desmodromic cam 51 and a second gear train connection 75, 87 transmits the rotational motion from the second interfolder roller 11 to the second desmodromic cam (not shown and symmetrical to cam 51). In this way, the rotational motions of the desmodromic cams and the alternating motions of the rotating shafts 39, 41 (and therefore of the separator fingers 21, 23) are synchronized with the rotational motion of the interfolding rollers 9, 11.

[0042] In other embodiments, a different transmission arrangement can be provided, for example using continuous belts to transmit the motion from the interfolding rollers 9, 11 to the desmodromic cams. However, the use of gear trains can be advantageous in terms of better motion control.

[0043] The use of desmodromic cams to control the oscillation movement of the separator fingers 21, 23 can be advantageous from at least two points of view. In the first place, these cams allow to reach a very high frequency of the reciprocating movement of oscillation with a good control of the movement. A number of separator finger oscillations can be achieved up to 25 oscillations per second or higher. Secondly, it is possible to easily change the motion law of the separator fingers by replacing the desmodromic cams with another set of desmodromic cams having different cam profiles.

[0044] While according to the embodiment illustrated in the drawings the desmodromic cams 51 are rotated by the same motor 81 which rotates the interfolding rollers 9, 11, in other embodiments an independent electric motor can be provided for each cam desmodromic. In still further embodiments, a single electric motor, independent of the motor 81, can be provided to rotate both desmodromic cams. If one or two independent motors are used to drive the desmodromic cams, these motors will be electronically controlled so as to rotate in synchronism with the interleaving rollers 9, 11. If independent motors are used for the desmodromic cams on one side and for the interleaving rollers on the Otherwise, the phase between the interfolding rollers and the desmodromic cams can be easily adjusted, for example by acting on one of these motors, typically on the motor or motors which control the rotation of the desmodromic cams.

[0045] According to some embodiments, the profiles of the desmodromic cams can be adapted to impart different speeds of motion to the separator fingers 21, 23 during the removal motion and the return motion, i.e. during the oscillatory movement away from the interfolding rollers 9, 11 and during the oscillatory motion towards the interfolding rollers 9, 11. More specifically, according to some embodiments, the removal movement, i.e. the movement with which the separator fingers 21, 23 detach the folded sheet from the respective interfolder roller 9 , 11, may be slower than the return movement. In other embodiments, the opposite can be provided, that is, the movement away can be faster than the return movement. The choice of which movement is faster may depend, among other things, on the characteristics of the material (tissue paper, for example) of which the sheets are made, the number of sheets per stack, the number of layers per sheet, and so on. Street. A slower removal movement can be advantageous, for example, in order to have a more delicate action on the tissue paper which prevents damage to it when the sheets are detached from the interleaving rollers 9, 11.

[0046] In order to form stacks of interleaved sheets S1, S2 containing a predetermined number of sheets, pairs of counting combs can be provided, as will be described later, referring specifically to Figs 1 to 5.

[0047] More specifically, referring in particular to Fig.2, a first pair of counting combs 91, 93 is arranged symmetrically in front of the interfolding groove 13, on the side where the separator fingers 21, 23 are arranged. counting combs 95, 97 is also arranged symmetrically in front of the interfolding groove 13.

[0048] For reasons of clarity, Fig.2 illustrates the two pairs of counting combs 91, 93 and 95, 97, while the separator fingers 21, 23 are omitted. In Fig. 7, described above in greater detail, the counting combs 91, 93, 95, 97 are omitted, to show in greater detail the structure of the separator fingers 21, 23. Fig. 1 illustrates both the separator fingers and the the counting combs in combination, to better illustrate their mutual position.

[0049] Each counting comb is movable in a first direction and in a second direction, along two translation axes X and Y. The X axis is orthogonal to the rotation axes 9A, 11A of the interfolding rollers 9, 11 and parallel to a plane containing the rotation axes 9A, 11A. The Y axis is orthogonal to the X axis and to the rotation axes 9A, 11A. The movement along the X and Y axes is controlled independently for each counting comb 91, 93, 95 and 97, since each counting comb has its own control unit. However, these movements are synchronized with each other and coordinated with each other, in a manner described below, in order to form sequences of stacks of interleaved sheets. The control units of the counting combs 91, 93, 95, 97 are marked with 101, 103, 105 and 107 respectively. The control units can be interfaced to a single control unit, so that their movements can be synchronized.

The control units 101 and 105 are substantially identical to each other and are in turn substantially symmetrical to the drive units 103, 107. The following detailed description therefore applies to all four control units 101-107. The structure of a control unit 103-107 is now described in greater detail with reference to Figs. 2 and 3.

[0051] Each control unit comprises a first electronically controlled electric motor 121 supported by a carriage 123. The carriage 123 supports a rotating shaft 125, which extends parallel to the rotation axes 9A, 11A of the first interfolder roller 9 and of the second Interleaving roller 11. Two toothed wheels 127A, 127B are keyed to the ends of shaft 125. The toothed wheel 127B meshes with an output gear 129 of the first electric motor 121, so that the rotation of the electric motor 121 is transmitted to both wheels toothed 127A, 127B.

[0052] The toothed wheels 127A, 127B mesh with respective racks 131A, 131B, which form part of a slide 133. The slide 133 comprises sides 135 on which the racks 131A, 131B are mounted. The sides 135 are connected to each other by means of a beam which forms part of the respective counting comb and which supports the teeth or prongs of the respective counting comb. In Fig. 3 the beam is marked with 93B and the prongs or teeth are indicated with 93A, and they cumulatively form the counting comb 93. As noted above, the remaining counting combs 91, 95 and 97 are substantially the same or symmetrical to the comb count 93, and therefore they too will have a beam supporting the respective prongs, the beam and the prongs forming part of the respective slide 133.

[0053] The slide 133 is mobile with reciprocating motion along the translation axis X with respect to the respective carriage 123. The reciprocating motion along the translation direction X is controlled by the first electric motor 121. To drive the slide 133 with respect to the corresponding carriage 123 guides 137 are provided, which extend along the translation direction X.

[0054] The carriage 123 of each drive unit 101, 103, 105, 107 is constrained to a continuous flexible member 141. In the embodiment illustrated in the drawings, the continuous flexible member 141 comprises two toothed belts which are driven around respective upper and lower pulleys 143, 145. The upper pulleys 143 can be mounted idle on the stationary frame 31. The lower pulleys 145 can be keyed onto a shaft 147, which can be driven in reciprocating rotary motion by a second electronically controlled electric motor 149. The rotation of the second electric motor 149 drives the carriage 123 along the Y direction. The second electric motor 149 selectively rotates clockwise and counterclockwise to move the carriage 123 up and down along the Y direction.

[0055] The arrangement described above is common to all the control units 101, 103, 105, 107. Therefore each control unit can control the reciprocating motion of the respective counting comb 91, 93, 95, 97 in the two directions parallel to the X axis and Y axis. A control unit 151 (Fig. 3) can be interfaced with each first and second electric motor 121, 149 of each counting comb 91, 93, 95, 97 to electronically control the motors and then the movement of the counting combs, in order to form stacks SK of folded sheets S1, S2.

[0056] By providing control units having the same structure for each of the four counting combs 91, 93, 95, 97, the construction and maintenance of the interfolding machine are simpler. The same spare parts can be used for all control units. Furthermore, it is also possible to have a single spare control unit in order to replace any one of the drive units present in the interfolding machine, in the event of a fault.

[0057] The operation of the counting combs 91, 93, 95, 97 can be controlled in different ways. Two possible operating sequences of the counting combs are shown in Figs 4A, 4B, 4C and 5A, 5B, 5C, respectively, and will be briefly described below. The movement of the counting combs is controlled so that stacks of a predetermined number of interleaved sheets can be produced.

[0058] Referring to Figs.4A, 4B, 4C, the two pairs of counting combs 91, 93, 95, 97 are controlled to perform the same operations, i.e. the first pair of counting combs 91, 93 performs the same operations of the second pair of counting combs 95, 97, but in an alternating manner, i.e. in a temporally staggered manner. In Fig.4A, the second pair of counting combs 95, 97 is moving (direction Y) to remove a first stack SK1 of folded sheets S1, S2 from the interleaving rolls 9, 11, so that a second stack SK2 of folded sheets S1, S2 can be formed on the second pair of counting combs 91, 93, which are positioned just below the interleaving rollers 9, 11 in front of the interleaving groove 13.

[0059] In Fig.4B the first pair of counting combs 91, 93 was moved down a short stroke, to allow the second stack SK2 to grow, while the first stack SK1 was unloaded from the second pair of combs count 95, 97. In this phase the first pair of counting combs 91, 93, which are supporting the SK2 stack being formed, moves downwards approximately at the rate of growth of the stack, that is, at the rate, at which it gradually increases the height of the stack being formed.

The second pair of counting combs 95, 97 can release the stack SK1 onto a conveyor, which removes the stack SK1 in a direction orthogonal to the figure.

[0061] After unloading the first stack SK1, the second pair of counting combs 95, 97 was returned to an upper position (moving along the respective direction Y). In Fig.4B the second pair of counting combs 95, 97 is in a neutral position. The combs 95, 97 are spaced from each other along the direction of the X axis, so that in this phase they do not interfere with the operation of the interleaving rollers 9, 11 and of the separating fingers 21, 23 (not shown in the sequence of Figs 4A, 4B, 4C), which continue to form the second stack SK2 on the first pair of counting combs 91, 93, which gradually moves downwards.

Once the required number of interleaved sheets S1, S2 has been stacked on the first pair of counting combs 91, 93 the counting combs 95, 97 of the second pair move towards each other in the direction of 'X axis, thus separating the SK2 stack from the subsequent incoming sheets. At the same time, or immediately thereafter, the counting combs 91, 93 move downwards (along the Y axis). In this way a third stack SK3 can begin to form on the second pair of counting combs 95, 97 as shown in Fig. 4C, while the first pair of counting combs 91, 93 moves downwards (along the direction of the Y axis), to remove the second SK2 stack.

[0063] As can be understood from the above brief description, and referring to Figs.4A, 4B, 4C, the two pairs of counting combs 91, 93 and 95, 97 perform the same action on sequentially formed stacks of sheets. This can be advantageous in terms of machine programming, as the control software becomes simpler.

[0064] When the pair of counting combs 91, 93 or the pair of counting combs 95, 97 is in the lower position, the stack supported on them can be discharged onto an evacuation conveyor, such as an evacuation belt , which can extend orthogonally to Figs 4A-4C, ie parallel to axes 9A, 11A. In the operating mode of Figs 4A, 4B, 4C, both pairs of counting combs 91, 93 and 95, 97 are adapted to perform a stroke from an upper position adjacent to the interfolding groove 13 (see for example counting combs 95 , 97 in Fig.4B), to a lower evacuation position, adjacent to the evacuation conveyor, see for example counting combs 95, 98 in Fig.4A.

[0065] The one described with reference to Figs.4A, 4B, 4C is not, however, the only possible operating mode of the counting combs. In the sequence of Figs 5A, 5B, 5C each stack SK1, SK2, SK3 is formed partially on the pair of counting combs 91, 93 and partially on the counting combs 95, 97. Only the counting combs 95, 97 have the task to unload the stacks formed on the evacuation conveyor. In other words, each stacking cycle is performed partially on the first pair of counting combs 91, 93 and partially on the second pair of counting combs 95, 97.

[0066] During the initial stage of forming the stack, each stack SK1, SK2, SK3 is supported by the counting combs 91, 93 up to a stage in which the stack is transferred from the first pair of counting combs 91, 93 to the second pair of counting combs 95, 97.

[0067] More specifically, when the first pair of counting combs 91, 93 and the second pair of counting combs 95, 97 are at the same height, i.e. at the same height, the counting combs 91, 93 are opened, i.e. they are spaced apart one from the other in the direction of the X axis, to unload the stack being formed on the second pair of counting combs 95, 97 which are waiting in a waiting position. Once the stack being formed has been transferred onto the second pair of counting combs 95, 97, the first pair of counting combs 91, 93 is moved upwards and returned to a position adjacent to the interfolding groove 13, where they await the start of the new stacking cycle.

Meanwhile, the second pair of counting combs 95, 97 is moved downward at the stack forming rate while supporting the forming stack. When the first stack SK1 is complete the counting combs 91, 93 are closed again (i.e. they are moved towards each other along the X axis), while the second pair of counting combs 95, 97 are moved further towards down (Y axis) at a speed higher than the stack growth rate. Once the second pair of counting combs 95, 97 has reached an unloading position, they are spaced from each other (movement along the X axis) to discharge from the first pair of counting combs 91, 93 the battery just received.

[0069] As soon as the stack SK1 has been unloaded from the second pair of counting combs 95, 97, the latter are moved upwards (Y direction) and brought closer to each other (X direction) in a position below the first pair of counting combs 91, 93. The second pair of counting combs 95, 97 is thus correctly positioned to receive the next stack SK2 which is being formed and which is temporarily supported by the first pair of counting combs 91, 93 .

The position in which the stack being formed is transferred from the first pair of counting combs 91, 93 to the second pair of counting combs 95, 97 can be adjusted as needed and can be selected on the basis of the number of sheets per stack and can be selected in such a way as to optimize the dynamics of the counting combs 91, 93 and 95, 97, that is, in such a way as to minimize the dynamic load on them.

[0071] The separation of the stacks is obtained by inserting at high speed the counting combs 91, 93 into the flow of sheets. Each counting comb is inserted (movement along the X axis) in phase with the sheet and with the separator fingers 21, 23. When the penultimate sheet is detached from the respective interleaving roller and is placed on the stack by the respective separator finger (the distal end of the separator fingers is positioned outside the cylindrical surface of the first interfolding roller 9) the first counting comb is inserted. When the last sheet is stacked and the respective separator finger is still on the stack, the second counting comb is inserted, completing the separation of the stack. The second counting comb is offset by one sheet with respect to the first counting comb. During the separation phase, or immediately after the separation phase, the counting combs 91, 93 are moved downwards, supporting the advancement of the new stack. According to the operating mode shown in Figs 5A, 5B, 5C, therefore, the first pair of counting combs 91, 93 moves up and down (Y axis) for a short stroke, required to allow the stack forming to grow between the interleaving rollers 9, 11 and the first pair of counting combs 91, 93. Conversely, the second pair of counting combs 95, 97 performs a longer vertical stroke, to remove each stack from the pair of rollers interleavers 9, 11.

[0072] In both operating modes (Figs.4A-4C and Figs.5A-5C) the movement in the X-axis direction of the counting combs can be adjusted to facilitate the separation of a complete SK stack from the flow of interleaved sheets incoming, fed by the interleaving rollers 9, 11. For this purpose, for example, the approach movement along the direction of the X axis of the counting combs that separate the complete stack from the next sheet can be out of phase, in the sense that the movement of one of the two counting combs is started before the other. In other words, the approaching movement of the counting combs in the X direction can be non-symmetrical, that is, not synchronous.

[0073] The movement of the counting combs is also synchronized with the oscillation movement of the separator fingers 21, 23 to facilitate the separation of each complete SK stack from the continuous flow of interfolded sheets arriving from the interfolding throat 13.

Claims (11)

INTERFOLIATING MACHINE WITH IMPROVED ARRANGEMENT OF COUNTING COMBS " Claims 1. An interfolding machine (1) comprising: a first interfolder roller (9) rotating around a first rotation axis (9A); a second interfolding roller (11) rotating about the second rotation axis (11A) parallel to the first rotation axis; wherein the first interfolding roller (9) and the second interfolding roller (11) form between them an interfolding groove (13); a first pair of counting combs (91, 93) arranged in front of the interfolding groove (13); a second pair of interfolding combs (95, 97) arranged in front of the interfolding throat (13); wherein each counting comb (91, 93, 95, 97) of said first pair of counting combs (91, 93) and of said second pair of counting combs (95, 97) is provided with a movement along two axes translation (X, Y), controlled by respective electronically controlled electric motors (121, 149). The interfolding machine (1) of claim 1, wherein each counting comb of said first pair of counting combs (91, 93) and of said second pair of counting combs (95, 97) comprises a respective unit of drive (101, 103, 105, 107) comprising said respective electronically controlled electric motors (121, 149). The interfolding machine 81) of claim 2, wherein each drive unit (101, 103, 105, 107) comprises in combination: a first electronically controlled electric motor (121) adapted to drive the respective counting comb (91, 93, 95, 97) in an alternating translation motion along a first direction (X), parallel to a plane containing the first axis of rotation (9A) and the second rotation axis (11A); a second electronically controlled electric motor (149) adapted to drive the respective counting comb (91, 93, 95, 97) in an alternating translation motion along a second direction (Y), orthogonal to the first direction (X) and to a plane containing the first axis of rotation (9A) and the second axis of rotation (11A). The interfolding machine (1) of claim 3, wherein each drive unit (101, 103, 105, 107) comprises a respective carriage (123) movable alternately along the second direction (Y) under the control of the respective second electric motor (149), in which the carriage (123) supports the respective first electric motor (121) and a slide (133); and in which each slide (133) is movable with respect to the carriage (123) along the first direction (X) under the control of the first electric motor (121). The interfolding machine (1) of claim 4, in which the carriage (123) of each drive unit (101, 103, 105, 107) is constrained to a continuous flexible member (141), and in which the respective second electric motor (149) is adapted to actuate the continuous flexible member (141) to move the carriage (123) in the second direction (Y). The interfolding machine (1) of any one of the preceding claims, wherein at least one of said first pair of counting combs (91, 93) and second pair of counting combs (95, 97) is controlled in such a way that their approaching movement along one of said two translation axes (X, Y) is out of phase, to facilitate the separation of a stack (SK) formed of interfolded sheets (F) from a continuous flow of sheets fed by the interfolding throat (13 ). The interfolding machine (1) of any one of the preceding claims, wherein the first pair of counting combs (91, 93) and the second pair of counting combs (95, 97) are controlled so that each of said first and second pair of counting combs gradually moves away from the interfolding groove (13) to receive on it a first stack (SK1) of interfolded sheets (F) and subsequently rapidly moves the first formed stack (SK1) into a position of unloading, while the other of said first and second pair of counting combs is arranged in front of the interfolding groove (13) to receive a second stack (SK2) of sheets interfolded thereon. The interfolding machine (1) of any one of claims 1 to 6, wherein the first pair of counting combs (91, 93) and the second pair of counting combs (95, 97) are controlled so that each of the subsequently formed stacks (SK1, SK2, SK3) of interleaved sheets (F) is at least partially formed on the first pair of counting combs (91, 93) and subsequently transferred to the second pair of counting combs (95, 97), which transfers each complete stack (SK1, SK2, SK3) to an unloading position. The interfolding machine (1) of one or more of the preceding claims, wherein the first pair of counting combs (91, 93) and the second pair of counting combs (95, 97) are both adapted to move along a direction orthogonal to a plane containing the rotation axes (9A; 11A) of the first interfolding roller (9) and of the second interfolding roller (11), from a position adjacent to the interfolding groove (13) to a lower unloading position, where each complete stack (SK1, SK2, SK3) of interleaved sheets can be evacuated from the counting combs. 10. A method for producing stacks (SK, SK1, SK2, SK3) of interleaved sheets (F) comprising the following steps: - feeding a continuous flow of interleaving sheets (F) from an interleaving groove (13) formed between a first interleaving roller (9) and a second interleaving roller (11), rotating around a respective first axis of rotation (9A) and a second axis of rotation (11A); - forming a first stack (SK1) of interfolded sheets (F) on a first pair of counting combs (91, 93) arranged in front of the interfolding throat (13) and close to each other, while said first pair of counting combs (91, 93) counting combs (91, 93) gradually moves away from the interfolding groove (13); wherein the first pair of counting combs (91, 93) is gradually moved away from the interfolding throat (13) while the first stack (SK1) of interfolded sheets grows; - upon completion of the first stack (SK1) of interleaved sheets (F), move the first pair of counting combs (91, 93) towards an unloading position, where the first stack (SK1) of interleaved sheets (F) is unloaded from the first pair of counting combs (91, 93) by moving the combs of said first pair of counting combs (91, 93) away from each other; and move the combs of a second pair of counting combs (95, 97) closer to each other in a closed position in front of the interfolding groove (13); - start the formation of a second stack (SK2) of interleaved sheets on the second pair of counting combs (95, 97), while the first pair of counting combs (91, 93) moves again from the unloading position to a position waiting area near the interfolding throat (13). 11. A method of producing stacks (SK, SK1, SK2, SK3) of interleaved sheets (F) comprising the following steps: - feeding a continuous flow of interleaving sheets (F) from an interleaving groove (13) formed between a first interleaving roller (9) and a second interleaving roller (11), rotating around a respective first axis of rotation (9A) and a second axis of rotation (11A); - forming a first stack (SK1) of interfolded sheets (F) on a first pair of counting combs (91, 93) arranged in front of the interfolding throat (13) and close to each other, while said first pair of counting combs (91, 93) counting combs (91, 93) gradually moves away from the interfolding groove (13); wherein the first pair of counting combs (91, 93) gradually moves away from the interfolding groove (13) while the first stack (SK1) of interfolded sheets grows; - transferring the first stack (SK1) of interleaved sheets (F) onto a second pair of counting combs (95, 97) by moving the counting combs of the first pair of counting combs (91, 93) away from them; - upon completion of the first stack (SK1) of interfolded sheets (F), moving the second pair of counting combs (95, 97) away from the interfolding groove (13) towards an unloading position; bring the combs of the first pair of counting combs (91, 93) close together, and start the formation of a second stack (SK2) of interfolded sheets (F) on the first pair of counting combs (91, 93).