MACHINE FOR PRODUCING STACKS OF FOLDED SHEETS OF PAPER AND METHOD THEREFOR

Abstract

Machine (1) for converting paper comprising a starwheel unit (10) equipped with at least one cylindrical body having a plurality of grooves (15), each of which is configured to receive a respective sheet (11) of a plurality of folded sheets (11) that are carried in turn, for example between two transmission belts (200, 201), along a feeding direction (101), for example a direction substantially tangential to the starwheel unit (10). The starwheel unit rotates about a rotation axis (110), for example in a counterclockwise direction, and discharges in turn the sheets (11) present in the grooves (15) onto a formation table (20, 120). More precisely, the folded sheets are discharged to achieve a predetermined angular release position, in order to form a stack (50) of folded sheets (11). The machine (1) can comprise a transfer means for transferring the formed stacks (50) from the table (20, 120) to said conveying means (30). The transfer means comprises a rotation means (60) arranged to transfer the stack (50) of folded sheets (11) from the table (20) to the conveying means (30) through a rotation of a predetermined angle.

Description

FIELD OF THE INVENTION

The present invention relates to the field of converting paper and similar products for making paper material in packages of folded sheets starting from web material.

In particular, the invention relates to a machine for making stacks of folded paper sheets, or similar products.

Furthermore, the invention relates to a method for making stacks of folded sheets.

BACKGROUND OF THE INVENTION

As well known, different types of machines and processes exist for obtaining stacks of folded paper sheets, or similar material, such as tissue paper, napkins, or similar articles.

A type of such machines has a transfer roller capable of rotating about an axis and peripherally provided with a predetermined number of curved blades. The blades extend starting from the roller in a direction which is opposite to the roller rotation direction and impart to the roller same a particular “star” shape from which the common name of “starwheel” derives.

Between two following curved blades the transfer roller is, therefore, equipped with a groove in which a feeding mechanism introduces in turn a sheet of a plurality of sheets already folded and fed in quick succession. The rotating transfer roller transfers the fed folded sheets into the grooves from a feeding position to an discharge position. In the discharge position a barrier is provided that causes the sheets to exit from the respective grooves, in such a way to accumulate the sheets on a formation table where a stack of overlapped sheets is formed. The different arrangement of the barrier can cause the products to be stacked along a vertical axis, onto one another, or along a horizontal axis, with the napkins leaning at an edge one after the other.

Once a predetermined height or length of the stack is achieved, under the starwheel unit, separators operate for separating the last sheet of the already finished stack from the first sheet of the successive stack. In case of vertical stacking, once the separation of two sheets is carried out, the table translates leaving the axis of the stack, which is located on it, substantially vertical up to arrange the stack on a conveyor belt. In case of horizontal stacking, the products can be directly released on a conveyor belt or other conveyor.

An example of this kind of machine with stacking along a vertical axis is disclosed in EP1421021. In this case for increasing the production rate, several coaxial starwheel units are provided that work in parallel. Each starwheel unit is associated to a conveyor belt to it dedicated on which the production of the stack of sheets is made. More precisely, each of parallel conveyors, one for each starwheel unit and having a conveying direction that is orthogonal to the axis of the starwheel unit, works discontinuously, i.e. during the transfer of the formed stack of sheets it remains still, whereas once transferred the stack, while the successive stack is forming, it shifts to a position for receiving a successive stack.

In both cases each stack of sheets has to be conveyed forward up to a banding station, or packaging station, where the stack is pressed and wound by a film of plastic material forming a pack. During the movement between the point in which the stack is released from the table onto the conveyor belt and the packaging station, the conveying direction of the stack is subjected to many variations, even sudden variations, which can damage the product and oblige to complicated technical solutions.

Therefore, in order to move the stacks of sheets, for example for feeding them to a banding section, it is necessary to start from different adjacent lines of stacks that are present on the above described conveyors which are parallel to each other, and bring them to a configuration, in which they are arranged in column on a single row. To obtain this configuration, a further conveyor belt is provided arranged orthogonally to the above described conveyors on which the production of the line is carried out, as described in IT2006BO00801 or IT2001RE00121.

A relevant and known drawback of the stacking machines of sheets of known type is a low flexibility.

In fact, the starwheel units of known type are capable of making both large-sized stacks, also called “bulk” stacks, for sale to restaurants, cafeterias, communities, or alternatively, smaller stacks, also known as “flat” stacks, for household or personal use. Therefore, in order to switch from a production to the other it is necessary to use two different machines.

In particular, in case of the “flat” stacks the folded sheets are stacked vertically and released overlapped on the formation table. So, the growth of the stack occurs vertically up to a predetermined height, rather low, and once completed its formation, the table withdraws from below of the stack for releasing it on a conveyor belt.

In case, instead, of “bulk” products, the folded sheets are released with the stack that grows horizontally, until it reaches a relevant length, and brought to the banding in a horizontal direction, as in the above cited application ITBO2006A000801.

In both cases, several stacks, or packs, are formed, which move from a configuration in which they are adjacent creating a line of stacks, to a configuration in which all of them are arranged in a row, in such a way that they can be fed to the banding section at the same time. Such configuration change can be carried out by a pusher that pushes in turn the stacks of a line on a second conveyor belt, that is parallel to the first, for being, then, fed to the banding section, in order to feed the stacks to the banding section it is therefore necessary to provide complicated conveying devices and proceed at a low speed.

As above disclosed, for feeding the stack to the banding section, which is arranged downstream of the formation section, it is necessary to operate a change of direction of the same stack, with the conveyor belts arranged orthogonally to one another. More precisely, the conveyor belt that is arranged downstream is adjacent to the conveyor belt that is arranged upstream but leaving a certain unavoidable gap, or discontinuity, between them. Therefore during the movement of the stack through the gap from a conveyor belt to the other it is possible to damage the product.

SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to provide a machine for making packages of folded sheets of paper, or similar products, which has a high production rate and has in the meantime a relatively small size.

It is also a feature of the present invention to provide a machine for making packages of folded sheets of paper, or similar products, which assists handling the stacks formed through the various sections of the machine and, in particular, up to a banding section, avoiding to damage the product along the path and simplifying structurally the machine.

It is another feature of the present invention to provide a machine for making packages of folded sheets of paper, or similar products, which can work continuously.

It is a further feature of the present invention to provide a machine for making packages of folded sheets of paper, or similar products, which is highly flexible and, in particular, capable of making both packages of large size, i.e. packages of “bulk” type, and smaller packages, i.e. packages of “flat” type, without substantial structural changes to the machine.

These and other objects are accomplished by the machine for making packages of folded sheets of paper, or similar material, such as napkins, or paper tissues, according to the present invention, comprising:

• • a feeding means for feeding a plurality of sheets along a predetermined feeding direction;
  • a starwheel unit mounted rotatable about a rotation axis, said starwheel unit arranged to receive said plurality of folded sheets and to put them in turn on a table, in order to form a stack of folded overlapped sheets according to a first predetermined stack direction;
  • a transfer means that is arranged to transfer a completed stack of folded sheets from said table to said conveying means, said conveying means arranged to convey said stack of folded sheets along a conveying direction;

whose main feature is that said transfer means comprises a rotation means which is arranged to rotate said stack of folded sheets for transferring said stack from said table to said conveying means, said rotation means configured to bring the axis of the stack from said first predetermined stack direction, when said formed stack is located on said formation table, to a second predetermined stack direction, when the formed stack is located on the conveying means.

In particular, the first predetermined stack direction can be selected from the group consisting of:

• • a substantially horizontal direction;
  • a substantially vertical direction;
  • a direction at a predetermined angle with respect to a horizontal plane.

Advantageously, the second predetermined stack direction is selected from the group consisting of:

• • a substantially vertical direction when the first predetermined stack direction is substantially horizontal;
  • a substantially horizontal direction when said predetermined stack direction is substantially vertical.

In particular, the transfer means may comprise, furthermore, a translation means that is arranged to translate said stack of folded sheets from said table to said conveying means.

Advantageously, a means is provided for selectively operating said translation means and said rotation means for transferring said stack of folded sheets from said table to said conveying means so that said stack of folded sheets lays on said conveying means with vertical or horizontal axis.

In particular, during the production of packs, or stacks, of folded sheets of “flat” type, the means for selectively operating is arranged to operate the translation means. In this case, the “flat” stack of folded sheets has a substantially vertical axis both when it is located on the table and when it is located on the conveying means once it has been transferred to it. Instead, during the production of packs, or stacks, of folded sheets of “bulk” type, the means for selectively operating is arranged to operate the rotation means. In this case, the “bulk” stack of folded sheets turns from a configuration with substantially vertical axis when it is arranged on the table to a configuration with a substantially horizontal axis when it is located on the conveying means. In fact, if the “bulk” stack were transported with the vertical axis free it could fall into pieces and so it would require to be pressed. This way, then, with a same stacking starwheel system, products of “flat” type and of “bulk” type can be provided. There is, therefore, a high production flexibility between the two types of products, and, in case a flexible banding machines is available, it is possible to change production very quickly.

Advantageously, downstream of the starwheel unit a banding section is provided in which to said folded sheet stacks a banding film is applied, for example a film of plastic material, said banding section arranged along said conveying direction, such that once arranged on said conveying means, said folded sheet stacks are carried along a single conveying direction substantially rectilinear up to entering said banding section.

Advantageously, the rotation means is arranged to rotate a stack of folded sheets of an angle set between 80° and 110°, in particular equal to 90°.

In particular, the transfer means can be adapted to transfer the stack of folded sheets from the table to the conveying means through a combination of movements that comprise the above described rotation and at least one translation.

Preferably, the conveying direction is substantially parallel to the rotation axis of said starwheel unit.

In particular, the table is substantially “comb-shaped”, which comprises a plurality of portions alternated to a plurality of empty spaces, said transfer means configured pass through said empty spaces for picking up said stack of folded sheets from said table and transferring it onto said conveying means.

Advantageously, the rotation means comprises a first and a second grip portions that, in use, are arranged at opposite sides with respect to said stack, in order to form substantially a gripper, said first and second grip portions arranged to move towards/away from each other between a release configuration for said stack of folded sheets and a gripping configuration for said stack of folded sheets, and vice-versa.

Preferably, the feeding means is arranged to feed a plurality of parallel rows of sheets to the starwheel unit, said starwheel unit comprising a plurality of coaxial starwheel elements each of which is arranged to process a respective row of sheets of said plurality of rows of sheets arranging in turn said sheets on said table, in order to obtain a respective stack of folded sheets for each row according to an axis oriented in a predetermined stack direction.

In particular, said plurality of starwheel units are configured to raise stacks of sheets at the same time on respective formation tables.

In this case, the transfer means, and, in particular, the rotation means, can transfer at the same time a plurality of folded sheet stacks from said formation table to said conveying means. This allows achieving a high production rate without the need of complex technical solutions for handling the stacks from the point of releasing the same onto the conveying means up to the banding section. In this case, the first and second grip portions of the transfer means has a length suitable for picking up at a same time all the formed stacks of sheets, for example vertically, by said starwheel and put them, for example horizontally, onto said conveying means.

In particular, the rotation means comprises a first plurality of gripping portions and a second plurality of gripping portions, said first and said second plurality of gripping portions arranged in use at opposite sides with respect to said plurality of stacks of sheets and being movable towards/away from each other between a gripping configuration for said folded sheet stacks and a release configuration for said folded sheet stacks, and vice-versa.

Advantageously, the conveying means comprises a conveyor belt.

Alternatively, the conveying means comprises a plane fixed support and a smooth surface on which a plurality of handling rods movable with respect to said plane support are arranged to push slidingly said stack of folded sheets along said conveying direction. It is also possible a combination of the two systems.

In particular, the conveying means has an end arranged at a predetermined distance from the banding section, such that between the conveying means and the banding section a predetermined distance is present.

Advantageously, the conveying means is associated with a pushing means that is arranged to push said folded sheet stacks to provide a predetermined acceleration to said folded sheet stacks, said push being applied by said pushing means when said folded sheet stacks have to reach a correct position directly into the banding machine. More precisely, said push is enough to cause the movement of said stacks of sheets directly from said conveying means into said banding section.

Preferably, the distance between two successive handling rods is higher than the width of the stack of folded sheets of a predetermined pitch, so that this pitch is travelled by the transfer means during the time necessary to the transfer means to reach the path of the conveying means, discharge the stack on the conveying means, and come avoid an interference with the path of the incoming conveying means. This allows the conveying means to work continuously, i.e. to avoid a stepwise operation that would be necessary to avoid the interference between the operation of the transfer means and of the incoming conveying means, and then to increase further the production rate of the machine.

Advantageously, the table is movable with respect to said starwheel unit, in order to follow the growth of said stack of folded sheets.

An exemplary embodiment of the invention comprises:

• • a first starwheel unit arranged to receive from a first feeding means a first plurality of folded sheets that are carried in turn along a first feeding direction and to overlap them on a first table, in order to form a first stack, or series of folded sheet stacks;
  • a second starwheel unit arranged to receive from a second feeding means a second plurality of folded sheets that are carried in turn along a second feeding direction and to overlap them on a second table, in order to form a second stack of folded sheets.

In particular, the transfer means is arranged to transfer alternatively, said first and second sheet stacks, or series of folded sheet stacks, on said conveying means.

In particular, the first and second starwheel units operate in an alternated way, in such a way that, whereas the first starwheel unit is creating a stack of sheets, the second starwheel unit is not supplied of folded sheets and the stack of folded sheets that has been just formed by the latter is transferred by said transfer means onto said conveying means, and vice-versa.

For example, the first and second starwheel units can be specular with respect to a midplane of the conveying means.

Advantageously, upstream of said, or each, starwheel unit the following are provided:

• • a longitudinal cutting means, arranged to divide a tape of paper, or similar material, into a plurality of strips;
  • a folding means that is arranged to fold said strips of paper in a predetermined configuration, in order to obtain said folded sheets that are fed to said starwheel unit along said feeding direction,
  • a transversal cutting means, arranged to cut said strips that are folded into strip portions into a length corresponding to a not folded napkin, and
  • a transversal folding means, for folding said strip portions into napkins.

According to another aspect of the invention a method for making stacks of folded paper sheets, or similar material, such as napkins, or paper tissues, comprises the steps of:

• • feeding a plurality of folded sheets to a starwheel unit along a feeding direction;
  • loading orderly said plurality of folded sheets onto a table by said starwheel unit, in order to form a stack of overlapped folded sheets;
  • transferring said stack of folded sheets from said table to said conveying means, which is arranged to convey said stack of folded sheets along a conveying direction;
  • handling said stack of folded sheets along a conveying direction;

whose main feature is that said transfer step from said table to said conveying means is carried out through a rotation of a predetermined angle of said stack of folded sheets, said rotation means configured to bring the axis of the stack from a first predetermined stack direction, when said formed stack is located on said formation table, to a second predetermined stack direction, when said formed stack is located on said conveying means.

Advantageously, downstream of said starwheel unit a step is provided of banding said folded sheet stacks, said step of banding carried out by a banding section by applying a banding film, for example a sheet of plastic material, about said stack of folded sheets.

In particular, the conveying step of said plurality of folded sheet stacks to said banding section is made along a single conveying direction. Therefore, once transferred on said conveying means, the folded sheet stacks are conveyed to the banding section along a single direction substantially rectilinear.

Advantageously, the step of transferring comprises the further steps of:

• • laterally approaching said stack of folded sheets by a first and second grip portions movable towards/away from with respect to each other;
  • approaching further said first and second grip portions to each other, in order to provide a compression of said stack of folded sheets;
  • rotating further said first and second grip portions to each other with said stack of folded sheets still compressed between them;
  • moving away said first and second grip portions from each other, in order to release said stack of folded sheets on said conveying means.

In an exemplary embodiment of the invention the following can be provided:

• • a first starwheel unit arranged to receive a predetermined number of folded sheets that are carried in turn along a first feeding direction and to overlap them on a first table, in order to form a first stack, or series of folded sheet stacks;
  • a second starwheel unit arranged to receive a predetermined number of folded sheets that are carried in turn along a second feeding direction and to overlap them on a second table, in order to form a second stack of folded sheets, in particular said second starwheel unit being specular to each other, i.e. arranged in a position symmetric with respect to said first starwheel unit.

Advantageously between the feeding means and the first and second starwheel units a deviation means is arranged to deviate alternatively the plurality of sheets towards the first, or towards the second starwheel unit.

In particular, either of the first and second starwheel units has a plurality of protruding portions, between two following protruding portions a groove being obtained arranged to receive a sheet of the above described plurality of sheets.

Advantageously, the first starwheel unit is associated with a first introduction means arranged to put a sheet in a groove along a first introduction direction and the second starwheel unit is associated with a second introduction means arranged to put a sheet in a groove along a second introduction direction. In particular, the deviation means is adapted to deviate alternatively said plurality of sheets towards said first and towards said second introduction means.

Advantageously, the deviation means comprises a deviation element having at least one guide surface arranged alternatively along the first introduction direction of the sheets in the first starwheel unit, or along the second introduction direction of the sheets in the second starwheel unit.

In an exemplary embodiment, the deviation means comprises a deviation element having a first and a second guide surface arranged to be alternatively, and respectively, put along the first introduction direction of the sheets at the first starwheel unit and along the second introduction direction of the sheets at the second starwheel unit.

In particular, an actuating rod can be provided operatively connected to said deviation means, said actuating rod arranged to move selectively said deviation means along the first, or the second, introduction direction respectively.

In an exemplary embodiment, the deviation means comprises at least one deviation roller equipped with:

• • a first holding means for keeping the sheets on a first angular portion of the surface of said deviation roller, said first angular portion ending at said first introduction means;
  • a second holding means for keeping said sheets, alternatively to said first means for keeping, on a second angular portion of the deviation roller surface, the second angular portion ending at the second introduction means.

In particular, the transfer means is arranged to transfer alternatively, said first and second sheet stacks, or series of stacks, of folded sheets on said conveying means.

According to a further aspect of the invention a conveying means is provided comprising a conveying unit for bringing a plurality of stacks, or packs, of sheets from a stacking section to a banding section, said conveying unit comprising a pushing means that is arranged to apply, during the movement of said conveying unit, an additional push on said folded sheet stacks to provide a predetermined acceleration to said folded sheet stacks, said additional push applied by said pushing means when said folded sheet stacks are approaching said banding section. More precisely, the above described additional push is enough to cause the movement of the stack of folded sheets towards said banding section, in a predetermined position of said banding section.

This way, the stack of sheets, which without the pushing means would be left by the conveying unit on the edge of said banding section, and would require a further handling for reaching a suitable banding position, by the pushing means is brought to a position at which banding can start a further handling of the stack of sheets.

In particular, the pushing means applies a push on the folded sheet stacks through a resilient means loaded by a cam means arranged close to said banding section. This way, additional drives are not necessary on board of the conveying means.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristic and the advantages of the machine for making packages of folded sheets of paper, or similar material, such as tissue papers, or napkins, according to the invention, will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings, in which like reference characters designate the same or similar parts, throughout the figures of which:

FIGS. 1 to 6 diagrammatically show in a elevational side view a possible succession of steps through which the machine operates, according to the invention, for making packages of folded sheets of paper, or similar material;

FIGS. 7A and 7B diagrammatically show an elevational side view of an exemplary embodiment of the machine shown in FIGS. 1 to 6 in two different operation steps;

FIGS. 8A and 8B diagrammatically show a perspective elevational side view of a possible exemplary embodiment of the table and of the transfer means in some operation configurations;

FIG. 9 diagrammatically shows a perspective elevational front view of a further exemplary embodiment of the machine of FIG. 1;

FIGS. 10 and 11 diagrammatically show a perspective elevational side view of another exemplary embodiment of the starwheel machine of FIG. 1;

FIG. 12 diagrammatically shows a perspective view of the banding section and the loading section of the machine of FIG. 1;

FIGS. 13 to 19 diagrammatically show elevational side views of a possible exemplary embodiment of the conveying means that can be associated with the machine of FIG. 1 and a pushing system at the exit from the conveying unit;

FIGS. 20 and 21 diagrammatically show an elevational side view of two different working configurations of the machine, according to the invention, for making packages of folded sheets of paper, or similar material;

FIGS. 22 to 27 show front elevational views of some possible exemplary embodiments of the deviation means adopted in the machine of FIG. 20;

FIG. 28 diagrammatically shows a perspective elevational side view of the machine of FIG. 20 equipped with the transfer means for highlighting further characteristic structural features.

DESCRIPTION OF A PREFERRED EXEMPLARY EMBODIMENT

With reference to FIG. 1, in a first exemplary embodiment a paper converting machine 1, according to the invention, comprises a starwheel unit 10 with at least one cylindrical body having a plurality of grooves 15, each of which is configured to receive a respective sheet 11 of a plurality of folded sheets 11. More in detail, the above described plurality of folded sheets 11 are carried in turn, for example between two transmission belts 200 and 201, along a feeding direction 101, for example a direction substantially tangential to starwheel unit 10. The latter rotates about a rotation axis 110, in the figure in a counterclockwise direction, and discharges in turn sheets 11 from grooves 15 onto formation table 20, 120. More precisely, the folded sheets are discharged to achieve a predetermined angular release position, in order to form a stack 50 of folded sheets 11. More in detail, the release of sheets 11 onto table 20, 120 is carried out, for example, by an extraction rod 18 arranged in the above described angular release position.

Upstream of starwheel unit 10 a cutting means can be provided, for example a cutting roller, not shown in the figures, arranged to divide longitudinally a sheet, or web, of paper into a predetermined number of strips that are then folded according to a predetermined configuration by folding means, also these not shown. The strips of folded paper thus obtained can be then divided into folded strip portions, by a transversal cut and then folded further to form napkins. Such process is of known type and then not shown in the figures.

While on a table 120 a stack being formed is present, on the other table 20 the stack already formed 50 is brought towards an outlet zone and then transferred by a transfer means 60, or 65, to said conveying means 30. The latter move stack 50 of folded sheets 11 along a conveying direction 102 (FIG. 9). Table 20, or 120, is provided movable towards/away from starwheel unit 10, in order to follow the growth of stack 50 of folded sheets and to return eventually to a position of minimum distance from starwheel unit 10 once rotation means 60 have drawn stack 50.

Each table, 20, 120, moreover, can work as separator, which separates the last sheet 11 of a formed stack 50, from the first sheet 11′ of the following stack 50′. More in detail, the following stack 50′ starts to grow on a table, in the figure table 120, whereas the formed stack 50 is transferred from the other table 20. Alternatively, a separator means can be provided, and a single formation table is used, in a way not described in detail since of known type in transfer systems of packages of folded sheets.

The transfer means can comprise translation means 65, shown advantageously only in FIG. 1, that is arranged to translate stack 50 of folded sheets from table 20 to conveying means 30, and can comprise a rotation means 60 arranged to transfer stack 50 of folded sheets 11 from table 20 to conveying means 30 through a rotation (FIGS. 2-6).

Preferably, translation means 65 and rotation means 60 are provided both. In this case, translation means 65 and rotation means 60 are selectively operated, in particular by a means for selectively operating not shown in the figures, for transferring stack 50 from table 20 to conveying means 30.

Rotation means 60 can be adapted to rotate formed stack 50 from a position in which it has the axis 55 arranged along a substantially vertical direction, when it is located on table 20, or 120, to a position in which the axis 55 is arranged along a substantially horizontal direction, at conveying means 30 (FIGS. 1 to 6).

In an exemplary embodiment diagrammatically shown in FIGS. 7A and 7B, stack 50 grows along a substantially horizontal direction. In this case, table 20, or 120, in order to follow the growth of stack 50, are arranged movable along a horizontal direction 220, in order to contain laterally stack 50 that, during the growth, is supported by a plane support 255. In this case, rotation means 60 is configured to cause the rotation of stack 50 from a position in which the axis 55 is arranged along a substantially horizontal direction, when it is located on table 20, or 120, to a position in which the axis 55 is arranged along a substantially vertical direction.

This way, during the production of packs, or stacks, of folded sheets of “flat” type, the translation means 65 is operated, so that the axis 55 of the “flat” stack of folded sheets remains substantially vertical also once transferred onto conveying means 30. Instead, during the production of packs, or stacks, of folded sheets of “bulk” type, the rotation means 60 is operated, which brings the “bulk” stack 50 from a configuration with axis 55 substantially vertical, when it is arranged on table 20, to a configuration with axis 55 substantially horizontal, when it is arranged onto conveying means 30. Therefore, according to the kind of product, “bulk”, or “flat”, the corresponding transfer means is selectively operated.

In case of the “bulk” product, the step of conveying stack 50 from table 20 to conveying means 30 is made through a combination of movements, comprising the above described rotation of stack 50 of a predetermined angle, for example set between about 80° and about 110°, and at least one translation of rotation means 60. The rotation of the stacks 50 made by rotation means 60 avoids the stacks 50 to move abruptly along conveying means 30 with a sudden variation of direction, in particular for bringing the sheet stacks 50 at a banding section, or packaging section 80. During the handling of stacks 50 of “bulk” type by conveying means 30, the axis 55 of the stacks 50 remains horizontal and is substantially orthogonal to conveying direction 102 (FIG. 9).

In a preferred exemplary embodiment, shown in detail in FIGS. 8A and 8B, table 20 has a “comb” shape comprising a plurality of support portions 21 alternated to a plurality of empty spaces 22. Therefore, the transfer means 60, which is also “comb-shaped”, is arranged to match the empty spaces 22 for picking up stack 50 of folded sheets and transferring it onto conveying means 30.

Rotation means 60 can comprise a first grip portion 61 and a second grip portion 62 that, in use, are arranged at opposite sides with respect to stack 50 and form substantially a gripper. More in detail, the first and second grip portions 61 and 62 of the gripper are provided that can be brought towards/away from each other between a gripping configuration of stack 50 and a release configuration of stack 50, and vice-versa. In particular, in the release configuration the gripping portions 61 and can approach laterally stack 50 and pass from an external position, in which stack 50 is arranged between them (FIG. 8A), and a compression configuration in which the gripping portions 61 and 62 compress stack 50 between them for transferring it onto conveying means 30 through the above described rotation (FIG. 8). After having rotated stack 50, the gripping portions 61 and 62 move away from each other to release stack 50 onto conveying means 30 (FIG. 5).

According to an exemplary embodiment of the invention, in case of packages, or stacks 50, of “bulk” type, the rotation means 60 transfer stack 50 of folded sheets from table 20 to conveying means 30 through the following combination of movements:

• • laterally approaching the gripping portions 61 and 62 to stack 50 of folded sheets in order to pass from a position external to stack 50 (dashed line in FIG. 2) to a position in which stack 50 is arranged between them;
  • approaching the first and second grip portions 61 and 62, in order to provide a compression of stack 50 of folded sheets between them (full line of FIG. 2);
  • possible translation of the first and second grip portions 61 and 62;
  • rotating the first and second grip portions 61 and 62 with stack 50 of folded sheets still compressed between them, in order put it over conveying means 30 (FIG. 3);
  • possible translation of the first and second grip portions 61 and 62 closed for placing stack 50 onto conveying means 30;
  • moving away relative to each other of the first and second grip portions 61 and 62, in order to release stack 50 of folded sheets onto conveying means 30 (FIG. 4).

In a particular exemplary embodiment of the invention, diagrammatically shown in FIG. 9, machine 1 provides a first starwheel unit 10 and a second starwheel unit 10′. More precisely, the first starwheel unit 10 is configured to receive a first plurality of folded sheets 11 that are carried in turn along a first feeding direction 101 and to overlap them on a first table 20, in order to form a first stack or series of stacks 50 of folded sheets, whereas the second starwheel unit 10′ is configured to receive a second plurality of folded sheets 11′ that are carried in turn along a second feeding direction 101′ and to overlap them on a second table 20′, in order to form a second stack 50′ of folded sheets. In this case, rotation means 60 is configured to transfer alternatively the stacks 50 and 50′ of folded sheets from the respective tables 20 and 20′ onto conveying means 30. In particular, the first and second starwheel units 10 and 10′ operate with a phase shift from each other for a predetermined time. Therefore, when stack 50 being formed on table 20 has achieved about the half of its final height, the transfer means 60 operate the conveying stack 50′ from table 20′ to conveying means 30, and vice-versa. Such technical solution allows, in particular, to increase remarkably production rate and to limit in the meantime the size of machine 1. Starwheel units 10 and 10′ are mounted specularly to the midplane 130 of conveying means 30 and have the respective rotation axes 110 and 110′ parallel to conveying direction 102.

As shown in the exemplary embodiment of FIGS. 10 and 11, starwheel unit 10 can comprise a plurality of starwheel elements, for example four coaxial starwheel elements 10a-10d. This way, the starwheel machine 10 is capable of making at the same time a plurality of stacks of folded sheets, for example four stacks 50a-50d, which grow at the same time on respective formation tables 20a-20d. In this case, rotation means 60 rotate at the same time the stacks 50a-50d during their transfer from the respective formation table 20a-20d to conveying means 30. In FIGS. 8A and 8B the gripping portions 61 and 62 have been indicated with a same length equal to the width of a package or stack 50. However, the gripping portions 61 and 62 may have a length suitable for picking up at a same time all the sheet stacks 50a-50d.

As diagrammatically shown in FIG. 12, downstream of starwheel unit 10 a banding section 80 is provided in which to the stacks 50 of folded sheets a banding film is applied 81, for example of plastic material, obtaining banded stacks 85.

The banding section 80 is arranged along conveying direction 102 at the end of conveying means 30, which move the stacks 50 from when they are discharged from the transfer means 60 up to banding section 80. Such technical solution assists remarkably, with respect to the machines of the prior art, the operations of handling the stacks 50 through machine 1 and to avoid possible damages to the product during the handling by means of changes of direction and passage from a conveying system to another.

Conveying means 30 can comprise a plane support 35, having low friction smooth surface, on which the stacks 50 of folded sheets are arranged, and a plurality of handling rods 36 movable with respect to the plane support 65 for pushing the stacks 50 of folded sheets along the above described conveying direction 102.

Once reached banding section 80, the sheet stacks 50 are transferred from plane support 35 on a platform 82. The latter is provided movable along a direction substantially orthogonal to conveying direction 102, i.e. along a vertical direction, for example, by at least one actuator 83 for bringing stack 50 from a first height to a second height between which banding film 81 extends. This way, as well known, stack 50, when passing from the first to the second height encounters banding film 81 that is wound about stack 50 obtaining a banded stack, or package 85, that is transferred to an exit conveyor belt 86. The means for banding the packages of folded sheets are indicated diagrammatically, and are well known to a skilled person, and then a detailed description thereof is not necessary.

In the possible exemplary embodiment of FIGS. 13 to 19 a handling system is provided formed by handling rods 36 that are integral to a carriage 150 moved by a chain mechanism 40 along a loop comprising two substantially horizontal portions 40a and 40b and two substantially vertical portions 40c and 40d (FIG. 13). In order to cause a carriage 150 to rotate at the connection between a horizontal portion 40a, or 40b, and the following vertical portion 40c, or 40d, the conveying means 30 is arranged at a minimum distance from the banding section 80, but sufficient, to make it possible a movement of the rod inbetween.

In particular, conveying means 30 end at a minimum distance 200 from a lifting platform 81 of banding section 80 and therefore, between conveying means 30 and lifting platform 81a distance is present 200 of minimum amplitude, enough to permit the passage of rod 36.

Also here the banding section is described only diagrammatically, since it is well known to a skilled person. The lifting platform 82 is movable by an actuator 83, for example a hydraulic actuator, along a direction 122 substantially vertical between a first height (FIG. 14) and a second height at which a banding film 81 is arranged that is wound about stack 50 (FIG. 12).

According to an aspect of the invention, each carriage 150 has a pushing element 38 integral to handling rod 36. More precisely, at the distance 200 the pushing element 38 is adapted to push the sheet stacks 50 to provide a predetermined acceleration to the stacks 50 same. The above described push is enough for causing the stacks 50 of folded sheets to travel the distance 200 and, then to pass directly from conveying means 30 to platform 81 of banding section 80. More precisely, pusher 38 is adapted to push stack 50 to a position substantially centred with respect to the banding film 82, in order to ensure that the step of banding is made correctly.

Upon reaching a desired position the pushing element 38 translates forward with respect to carriage 150 operated by a mechanism comprising a fixed cam means 161 arranged at a predetermined position and cooperating with a mobile cam means 151 integral to carriage 150. More in detail, mobile cam means 151 is integral to a chain 45 mounted to carriage 150. Until it reaches the position at which the fixed cam means 161 is arranged, chain 45 and mobile cam means 151 to it integral remain still (FIG. 14). When the mobile cam means 151 reaches an interference with fixed cam means 161, chain 45 starts to move (FIG. 15) causing a forward translation of the pushing element and, then, of handling rod 36 that pushes stack 50 forward. This produces an acceleration of stack 50 suitable for travelling all the distance 200 (FIGS. 16 and 17). During a following tilting step of carriage 150 the mobile cam means 151 is disengaged from the fixed cam means 161 and the pushing element 38, by a spring that is loaded during the movement of the pushing means, withdraws quickly up to returning to the starting position (FIG. 18) whereas the fixed cam means 161 reaches an interference with a mobile cam means 151′ of a successive carriage 150′.

During the handling steps along conveying direction 102, the stacks 50 are contained laterally by side containing walls 32 and 33 (FIG. 10).

Alternatively to what above described, conveying means 30 can comprise a conveyor belt, not shown in the figures.

In FIGS. 20 to 28 an exemplary embodiment is diagrammatically shown of machine 1 for making packages, or stacks 50 of folded sheets 11 of paper, or similar material, such as napkins, or paper tissues. As shown for example in FIGS. 20 and 21, machine 1 comprises a feeding means 121 for feeding a plurality of sheets 11 along a predetermined feeding direction 101′.

In this case, machine 1 comprises a first starwheel unit 10 that is mounted rotatable about a first rotation axis 110 and a second starwheel unit 10′ mounted rotatable about a second rotation axis 110′ parallel to the axis 110. In particular, each starwheel is configured to receive selectively the above described plurality of folded sheets 11 and to put them in turn onto a first table 20 and a second table 20′, respectively. This way, the first and second starwheel units 10 and 10′ form respectively a first and a second stack of folded overlapped sheets 50, and 50′ (FIGS. 20 and 21).

More in detail, between the feeding means 121 and starwheel units 10 and 10′ a deviation means 250 is arranged to deviate alternatively the above described plurality of sheets 11 towards first starwheel 10 (FIG. 20), or towards second starwheel 10′ (FIG. 21). Like first starwheel unit 10, also second starwheel 10′ has a plurality of grooves 15′, each of which is arranged to receive a sheet 11 of the above described plurality of sheets.

Each starwheel unit 10, or 10′, is associated with respective introduction means 210, or 210′, for example two conveyor belts 200 and 201, or 200′ and 201′, arranged to put a sheet 11 in a respective groove 15, or 15′. More precisely, the introduction means 200 supply sheets 11 to the starwheel 10 along a first introduction direction 101, whereas the introduction means 210′ supply sheets 11 to the starwheel 10′ along a second introduction direction 101′.

As diagrammatically shown in FIGS. 22 to 25, the deviation means 250 can comprise a deviation element 250 having at least one guide surface 251 arranged alternatively along the first introduction direction 101 for feeding sheets 11 towards first starwheel unit 10 (FIG. 22), or along the second introduction direction 101′ for feeding sheets 11 towards second starwheel unit 10′ (FIG. 23). For example, the deviation element 250 can be mounted rotatable about a rotation axis 255.

In a possible exemplary embodiment diagrammatically shown in FIGS. 24 and 25, the deviation means 250 can comprise a deviation element 250′, for example substantially wedge shaped, having a first guide surface 251a and of a second guide surface 251b which can be alternatively, and respectively, put along the first introduction direction 101 for feeding starwheel 10 (FIG. 24) and along second introduction direction 101′ for feeding starwheel 10′ (FIG. 25).

In particular, an actuating rod is provided 70 operatively connected to one end to deviation element 250′ and at the other end to an cam 75. Therefore, the actuating rod 70 is arranged between an advanced position in which the deviation element 250′ has the guide surface 251a arranged along the first introduction direction 101 and therefore sheets 11 are fed to the first starwheel unit 10 (FIG. 24), and a withdrawn position, in which the deviation element 250′ moves with the guide surface 251b along introduction direction 101′ and therefore sheets 11 are fed to starwheel unit 10′ (FIG. 25). In particular, for bringing the deviation element 250′ from the actual position of FIG. 24 to the position of FIG. 25, or vice-versa, handling rod 70 translates, thus withdrawing, or advancing, and causing the rotation of deviation element 250′ about a rotation axis 255′ in a rotation direction, or in the opposite direction.

In a further exemplary embodiment diagrammatically shown in FIGS. 26 and 27, the deviation means 250 comprises at least one deviation roller 25 having a first holding means, for example a suction means not shown in the figure, and for example as described in WO2011015893 in the name of the same applicant, for keeping sheets 11 at a first angular portion 26 of its surface, i.e. that correspond to centre angle α. More in detail, the first angular portion 26 ends at the first introduction means 210 comprises for example a second deviation roller 35, which also has a holding means, for example means suction, and arranged to transfer sheets 11 from the deviation roller 25 towards the introduction direction 101 to starwheel 10.

The deviation roller 25 also comprises a second holding means, also not shown in the figures, for holding, alternatively to the first holding means, sheets 11 on a second angular portion 27 of the surface of said deviation roller 25, i.e. that correspond to centre angle β. More in detail, the second angular portion 27 ends at second introduction means 210′ comprising a third deviation roller 36, which also has a holding means, for example a suction means, and arranged lead sheets 11 from the deviation roller 25 towards introduction direction 101′ of the starwheel 10′. Other configurations are possible for deviating the sheets by means of vacuum transfer rollers. For example conveyor belts 200 and 200′a can contact directly the vacuum roller 11.

Alternatively, the introduction means 200 and 200′ can be movable, in particular alternatively, towards/away from the deviation roller for transferring sheets 11 from the deviation roller 25 to starwheel 10, or 10′.

As diagrammatically shown in FIG. 28, furthermore, a conveying means is provided 30 arranged to bring the stacks 50 along a conveying direction 105 substantially parallel to rotation axes 110 and 110′ of starwheel units 10 and 10′. In particular, the first and second starwheel units 10 and 10′ are arranged in symmetrical positions with respect to an axis of symmetry 130 orthogonal to conveying direction 105. In this way the same rotation means 60 can be used for transferring the stacks 50 and 50′ from the respective formation tables 20 and 20′ onto conveying means 30.

The foregoing description of specific exemplary embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, then it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.

Claims

1. Machine for making stacks of folded paper sheets, or similar material, such as napkins, or paper tissues, comprising: characterised in that said transfer means comprises a rotation means which is arranged to rotate said stack of folded sheets for transferring said stack from said table to said conveying means, said rotation means configured to bring the axis of the stack from said first predetermined stack direction, when said formed stack is located on said formation table, to a second predetermined stack direction, when said formed stack is located on said conveying means.

a feeding means for feeding a plurality of sheets along a predetermined feeding direction;

a starwheel unit mounted rotatable about a rotation axis, said starwheel unit arranged to receive said plurality of folded sheets and to put them in turn on a table, in order to form a stack of folded overlapped sheets according to a first predetermined stack direction;

a transfer means that is arranged to transfer a completed stack of folded sheets from said table to said conveying means, said conveying means arranged to convey said stack of folded sheets along a conveying direction;

2. Machine, according to claim 1, wherein said first predetermined stack direction is selected from the group consisting of:

a substantially horizontal direction;

a substantially vertical direction;

a direction at a predetermined angle with respect to a horizontal plane.

3. Machine, according to claim 1, wherein said second predetermined stack direction is selected from the group consisting of:

a substantially vertical direction when said predetermined stack direction is substantially horizontal;

a substantially horizontal direction when said predetermined stack direction is substantially vertical.

4. Machine, according to claim 1, wherein said transfer means comprises, furthermore, a translation means that is arranged to translate said stack of folded sheets from said table to said conveying means, and a means is provided for selectively operating said translation means and said rotation means for transferring said stack of folded sheets from said table to said conveying means.

5. Machine, according to claim 4, wherein during the production of packs, or stacks, of folded sheets of “flat” type said means for selectively operating operate said translation means such that a “flat” stack of folded sheets remains substantially with vertical axis both on the table and on said conveying means once transferred.

6. Machine, according to claim 4, wherein during the production of packs, or stacks, of folded sheets of “bulk” type said means for selectively operating is arranged to operate said rotation means for bringing said “bulk” stack of folded sheets from a configuration with substantially vertical axis when it is arranged on said table, to a configuration with axis substantially horizontal when it is located on the conveying means.

7. Machine, according to claim 1, wherein downstream of said starwheel unit a banding section is provided in which to said stack of folded sheets a banding film is applied, said banding section arranged along said conveying direction, such that once arranged on said conveying means, said stack of folded sheets moves along a single conveying direction substantially rectilinear up to entering said banding section, in particular said conveying direction is substantially parallel to said rotation axis of said starwheel unit.

8. Machine, according to claim 1, wherein said transfer means is arranged to transfer said stack of folded sheets from said table to said conveying means through a combination of movements that comprise a rotation of the stack of folded sheets for an angle set between 80° and 110°, in particular 90°.

9. Machine, according to claim 1, wherein said table has is substantially “comb”-shaped, comprising a plurality of portions alternated to a plurality of empty spaces, said transfer means configured to be put at said empty spaces for picking up said stack of folded sheets from said table and transferring it onto said conveying means, in particular said rotation means comprises a first and a second grip portions that can be brought towards/away from each other between a gripping configuration of said folded sheet stacks and a release configuration of said folded sheet stacks, and vice-versa.

10. Machine, according to claim 1, wherein said feeding means is arranged to feed a plurality of parallel rows of sheets to said starwheel unit, said starwheel unit comprising a plurality of coaxial starwheel elements each arranged to process a respective row of sheets of said plurality of rows of sheets arranging in turn said sheets on said table, in order to make a respective stack of folded sheets for each row according to an axis oriented in a predetermined stack direction.

11. Machine, according to claim 10, wherein said rotation means is adapted to transfer at the same time said plurality of folded sheet stacks from said formation table to said conveying means.

12. Machine, according to claim 1, wherein said conveying means has an end close to a banding section, said conveying means being associated with a pushing means that is arranged to push said folded sheet stacks to provide a predetermined acceleration to said folded sheet stacks, said pushing means configured to apply said push in said conveying direction for displacing said stack directly to said banding station.

13. Machine, according to claim 12, wherein said conveying means comprises a plane support on which a plurality of handling rods, movable with respect to said plane support, move said stack of folded sheets along said conveying direction, in particular the distance between two successive handling rods being higher than the width of said stack of folded sheets, in order to cause the conveying means to work continuously.

14. Machine, according to claim 1, comprising:

a first starwheel unit arranged to receive from a first feeding means a first plurality of folded sheets that are carried in turn along a first feeding direction, and to overlap them on a first table, in order to form a first stack, or series of folded sheet stacks;

a second starwheel unit arranged to receive from a second feeding means a second plurality of folded sheets that are carried in turn along a second feeding direction and to overlap them on a second table, in order to form a second stack of folded sheets, in particular said first and said second starwheel units configured to work in an alternated way, in such a way that, while said first starwheel unit is creating a stack of sheets, said second starwheel unit is not supplied of folded sheets and the stack of folded sheets that has been just formed by the latter is transferred by said transfer means onto said conveying means, and vice-versa.

15. Machine, according to claim 1, comprising: wherein each starwheel unit among said first and said second starwheel unit has a plurality of protruding portions, between two following protruding portions a groove being obtained arranged to receive a sheet of said plurality of sheets; and wherein between said feeding means and said first and second starwheel units a deviation means is arranged to deviate alternatively said plurality of sheets towards said first, or said second starwheel unit.

a first starwheel unit mounted rotatable about a first rotation axis, said first starwheel unit arranged to receive said plurality of folded sheets and to put them in turn on a first table, in order to provide a first stack of overlapped folded sheets;

a second starwheel unit mounted rotatable about a second rotation axis parallel to said first rotation axis, said second starwheel unit arranged to receive said plurality of folded sheets and to put them in turn on a second table, in order to provide a second stack of overlapped folded sheets;

16. Machine, according to claim 15, wherein said first starwheel unit is associated with a first introduction means, said first introduction means arranged to put a sheet in a groove along a first introduction direction and said second starwheel unit is associated with a second introduction means, said second introduction means arranged to put a sheet in a groove along a second introduction direction, said deviation means arranged to deviate alternatively said plurality of sheets towards said first and towards said second introduction means.

17. Machine, according to claim 15, wherein said deviation means comprises a deviation element having at least one guide surface arranged alternatively along said first introduction direction of said sheets in said first starwheel unit, or along said second introduction direction of said sheets in said second starwheel unit.

18. Machine, according to claim 15, wherein said deviation means comprises a deviation element having a first and a second guide surface arranged to be alternatively, and respectively, put along said first introduction direction of said sheets into said first starwheel unit and along said second introduction direction of said sheets into said second starwheel unit.

19. Machine, according to claim 15 wherein an actuating rod is provided operatively connected to said deviation means, said actuating rod arranged to move selectively said deviation means along said first, or said second, introduction direction respectively.

20. Machine, according to claim 15, wherein said deviation means comprises at least one deviation roller equipped with:

a first holding means for keeping said sheets on a first angular portion of the surface of said deviation roller, said first angular portion ending at said first introduction means;

a second holding means for keeping said sheets, alternatively to said first means for keeping, on a second angular portion of the surface of said deviation roller, said second angular portion ending at said second introduction means.

21. Method for making stacks of folded paper sheets, or similar material, such as napkins, or paper tissues, comprising the steps of: characterised in that said transfer step from said table to said conveying means is carried out through a rotation of a predetermined angle of said stack of folded sheets, said rotation configured to bring the axis of the stack from a first predetermined stack direction, when said formed stack is located on said formation table, to a second predetermined stack direction, when said formed stack is located on said conveying means.

feeding a plurality of folded sheets to a starwheel unit along a feeding direction;

releasing said plurality of folded sheets onto a table by said starwheel unit, in order to form a stack of overlapped folded sheets;

transferring said stack of folded sheets from said table to said conveying means, which is arranged to convey said stack of folded sheets along a conveying direction;

handling said stack of folded sheets along a conveying direction;

22. A conveying unit for bringing a plurality of stacks, or packs, of sheets from a stacking section to a banding section characterised in that said conveying unit comprises a pushing means that is arranged to apply, during the movement of said conveying unit, an additional push on said folded sheet stacks to provide a predetermined acceleration to said folded sheet stacks, said additional push applied by said pushing means when said folded sheet stacks are approaching said banding section.