Forming station for forming absorbent cores of disposable hygiene products - Patent Application 20070122997

Abstract

The present invention relates to the field of manufacturing and packaging for disposable hygiene products, such as diapers and / or absorbent pads for babies, adults and animals. More particularly, the present invention relates to a forming station (1) for forming absorbent cores of disposable hygiene products of the type comprising at least one ply (2) interspersed with cellulose. The forming station (1) comprises: a frame (3); means for feeding cellulose flakes and means for feeding the ply (2) in a feeding direction (x), adapted to convey a flow of cellulose flakes towards the ply; a perforated belt (5) adapted to support the ply as it is fed forward; a suction hood (6) positioned below the belt (5) and adapted to suck the cellulose and lay it flat on the ply (2); a plurality of horizontal-axis rotating brushes (7) arranged transversely to the feeding direction (x) of the ply (2); a screen (8) with a plurality of holes (8') arranged between the brushes (7) and the ply (2); and means for "back and forth" alternating movement of the screen (8) parallel to the feeding direction (x) of the ply (2). The brush (7) is in functional contact with the screen (8) and the cellulose flakes are adapted to pass through the holes (8') in the screen (8) as urged by the suction hood (6) and the combined movement of the brush (7) and the screen (8).

Description

[Technical Field]

[0001] The present invention relates to the field of production lines for disposable hygiene products, such as diapers and / or absorbent pads, for example for babies, adults and animals, as well as packaging lines.

[0002] More particularly, the present invention relates to a forming station for forming absorbent cores of disposable hygiene products of the type comprising at least one ply interspersed with cellulose. [Background technology]

[0003] The forming station for forming the absorbent core receives the cellulose flakes produced by the crushing rolls and, using a suction hood, distributes them onto a ply also made of cellulose that is unwound and fed in the feed direction.

[0004] Known types of forming stations are: -frame; - means for feeding cellulose flakes, comprising at least one duct adapted to convey a flow of cellulose flakes towards the ply; - a perforated belt adapted to support the ply as it is fed forward; a suction hood positioned below the belt and adapted to suck the cellulose and lay it flat on the ply; and a rotating leveling brush positioned downstream of the duct through which the cellulose is fed and above the ply so as to lightly contact it, and adapted to level the layer of cellulose flakes just deposited on the ply; Equipped with.

[0005] Based on the various possible applications, the suction hood can be of rotary or flat belt type, thereby modifying the shape and distribution of the various mechanical elements while maintaining the same function.

[0006] This forming station has several limitations and drawbacks, which are particularly evident in faster production lines and for the formation of particularly thin absorbent cores.

[0007] The first drawback stems from the fact that the cellulose flakes taken from the crushing rolls, due to the turbulent motion created by the suction of the hood, tend to become electrostatically charged and to agglomerate when deposited on the ply.

[0008] As a result, the cellulose deposits unevenly on the ply; voids alternate with clumps of cellulose, which makes it difficult to distribute the leveling brush located downstream.

[0009] In any case, the leveling brush requires a large energy expenditure, resulting in increased costs.

[0010] These drawbacks are offset by the fact that the absorbent core is thinner and therefore very light (15 g / m 2 This is even more obvious because it weighs less than 100g. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention aims to overcome these limitations and provides a forming station for forming absorbent cores of disposable hygiene products that distributes cellulose flakes evenly, with minimal thickness and gram weight, making it efficient, accurate, and speeds up production.

[0012] Another object of the present invention is to: - To achieve a thin absorbent core to facilitate subsequent packaging containing hygiene products, reducing the volume of the final package, optimizing the use of warehouse space and reducing transportation costs; - To achieve an absorbent core with a uniform cell source layer for uniform absorption; and - To achieve an absorbent core with high quality and finish to reduce discomfort to the user; is. [Means for solving the problem]

[0013] These objects are achieved by a forming station for forming an absorbent core of a disposable hygiene product of the type comprising at least one ply interspersed with cellulose, the forming station comprising: -frame; - means for feeding cellulose flakes, comprising at least one duct adapted to convey a flow of cellulose flakes towards the ply; -means for feeding the ply in the feeding direction; - a perforated belt adapted to support the ply as it is fed forward; a suction hood positioned below the belt and adapted to suck the cellulose and lay it flat on the plies; Here are the forming stations: - several horizontal-axis rotating brushes arranged transversely to the ply feeding direction; -Screen with a number of holes arranged between the brush and the ply; - means for the "back and forth" alternating movement of this screen, parallel to the ply feed direction; and the brush is adapted to be in operative contact with the screen and the cellulose flakes are urged through the perforations of the screen by the suction hood and the combined movement of the brush and screen; It is characterized by:

[0014] According to a first aspect of the invention, the forming station comprises a cellulose accumulation unit, which is arranged between a screen and a perforated belt and is closed around its periphery so that it can be placed under reduced pressure by a suction hood.

[0015] In particular, the gathering unit comprises a first pair of side walls parallel to the feeding direction of the ply and a second pair of side walls perpendicular to the feeding direction.

[0016] Advantageously, the forming station comprises adjustment means for adjusting the mutual position of the side walls parallel to the feed direction of the plies, to vary the dimensions of the accumulated unit according to the width of the plies.

[0017] According to another aspect of the invention, each side wall perpendicular to the infeed direction is provided with a roller, which is adapted to rest on the plies to seal the accumulation unit and allow the plies to be fed forward.

[0018] Advantageously, the collecting unit comprises a sealing system with scraper blades positioned in contact with each roller to ensure the tightness of the collecting unit.

[0019] According to a possible embodiment, the means for "back and forth" alternating movement of the screen comprises at least a connecting rod and a crank mechanism.

[0020] In particular, this crank is made of a wheel provided with selective fixing means for a connecting rod along its radial direction to adjust the range of the "back and forth" alternating movement of the screen.

[0021] Advantageously, the frame comprises a track and the screen comprises wheels adapted to cooperate with said track.

[0022] In a preferred embodiment, the suction hood comprises an extractor, a horizontal conveyor, and a vertical conveyor joined together by flanges.

[0023] According to another aspect, the horizontal conveyor comprises a suction inlet over which a perforated belt travels, the ply resting on the perforated belt, the suction inlet comprising blade blocking means for adjusting the opening thereof.

[0024] In a possible variant of the invention, the horizontal and vertical conveyors each comprise a plurality of interior walls which divide the interior walls into horizontal and vertical chambers, respectively.

[0025] More preferably, the horizontal and vertical conveyors are provided with shutters adapted to regulate the suction flow in these chambers, and with externally operable control means for said shutters.

[0026] In a possible variant of the invention, the cellulose flake feeding means comprises two ducts arranged successively in the feeding direction of the ply; a feeding duct for feeding the superabsorbent material is interposed between these ducts.

[0027] In particular, the screen has a central opening directly connected to an inlet duct for feeding the superabsorbent material, thereby advantageously serving to deposit the superabsorbent material directly between the first and second layers of cellulose flakes.

[0028] The present invention has many advantages.

[0029] The rotating movement of the brushes combined with the alternating "back and forth" movement of the screen, aided by the suction of the suction hood, favors an even distribution of the cellulose flakes on the ply.

[0030] The rotating brush lightly touches the surface of the screen, entraining the cellulose flakes towards the holes in the screen.

[0031] The alternating "back and forth" motion of the screen ensures an even distribution of the cellulose, thereby achieving a substantially consistent layer of cellulose on the ply.

[0032] A uniform thickness of cellulose results in a layer without lumps or voids, with the added benefit of achieving a final core with uniform absorbent capacity.

[0033] Advantageously, with the correct distribution of cellulose, the required absorbency is equal to 10-15 g / m 2 This allows for a thinner, lighter core that weighs about the same.

[0034] Possible variations in the screen, with appropriately sized holes, allow for appropriate separation of various cellulose amounts without the need to intervene in other components of the forming station.

[0035] The leveling brushes conventionally positioned downstream of the cellulose infeed duct are no longer required.

[0036] The forming station can be easily adapted to the shape of the ply.

[0037] The suction system can be easily shut off to optimize vacuum flow.

[0038] The advantages of the present invention will become more apparent from the following description in which preferred embodiments are described by way of non-limiting example with the aid of the drawings. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a perspective view of a forming station for forming an absorbent core of a disposable hygiene product according to the present invention; FIG. [Figure 2] 1 is a longitudinal cross-sectional view of a forming station for forming an absorbent core of a disposable hygiene product according to the present invention; [Figure 3] 2 is a perspective view of a portion of the forming station of FIG. 1, viewed from below. [Figure 4] 6 is a perspective view of a detail of a forming station according to the present invention, taken at a different angle than FIG. 5; [Figure 5] 5 is a perspective view of a detail of a forming station according to the present invention, taken at a different angle than in FIG. 4. [Figure 6] FIG. 6 is a detailed cross-sectional view of FIG. 5. [Figure 7]2 is a perspective view of components in the forming station of FIG. 1; [Figure 8] FIG. 3 is a detailed cross-sectional view of FIG. 2. [Figure 9] 10 is a perspective view of components of a forming station according to a possible variant of the invention; FIG. [Figure 10] 10 is a perspective view of components of a forming station according to a possible variant of the invention; FIG. [Figure 11] 10 is a perspective view of components of a forming station according to a possible variant of the invention; FIG. [Figure 12] 10 is a perspective view of components of a forming station according to a possible variant of the invention; FIG. [Figure 13] 10 is a perspective view of components of a forming station according to a possible variant of the invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0040] With reference to the figure, there is shown a forming station 1 for forming absorbent cores of disposable hygiene products, such as diapers or absorbent underpads, for example for children, adults or animals.

[0041] This absorbent core is of the type comprising at least one ply 2 interspersed with cellulose flakes. In a possible variant, the absorbent core also comprises granules of superabsorbent material held between the cellulose.

[0042] The ply 2, also made of cellulose, is typically supplied on a reel and is unwound upstream of the forming station 1.

[0043] These cellulose flakes are produced by crushing rolls also located upstream of forming station 1 .

[0044] The forming station 1 shown is of the flat chamber type, but the same features can also be applied to a drum-type forming station, which represents a variation in which a perforated belt advances over a drum placed under vacuum, and the forming chamber is shaped to fit this drum.

[0045] Referring to the assembly in Figures 1 and 2, forming station 1 basically consists of: - Frame 3; - means for feeding cellulose flakes, comprising at least one duct 4 or two ducts 4 adapted to convey a flow of cellulose flakes towards the ply 2; a perforated belt 5 adapted to support the ply 2 as it is fed forward in the direction x; a suction hood 6 positioned below the perforated belt 5 and adapted to suck the cellulose and lay it flat on the ply 2; - several horizontally-axis rotating brushes 7 arranged transversely to the feeding direction x of the ply 2; - first motor means 28 of the brushes 7; - a screen 8 with a number of holes 8', arranged between the brush 7 and the ply 2; - means for the "back and forth" alternating movement of the screen 8, parallel to the feeding direction x of the ply 2; - second motor means 29 of the screen 8; and a cellulose accumulation unit 9, placed between the screen 8 and the perforated belt 5, closed around its periphery so that it can be placed under reduced pressure by the suction hood 6; Equipped with.

[0046] The brushes 7 are in functional contact with the screen 8 by lightly touching it with the ends of the brushes, and each of the brushes 7 is provided with its own motor means 28 .

[0047] Essentially, the brushes 7 are adapted to lightly touch the screen 8 during their rotational movement, while the holes 8' in the screen 8, shown in detail in Figure 7, allow the passage of cellulose from the infeed duct 4 to the accumulation unit 9 until it reaches the ply 2.

[0048] The cellulose flakes are urged by a suction hood 6 in combination with the rotary movement of the brush 7 and the alternating "back and forth" movement of the screen 8, and are adapted to pass through the holes 8' in the screen 8.

[0049] With particular reference to FIG. 3, the frame 3 is adapted to create a support and fixing structure for, for example, two ducts 4 through which the flow of cellulose flakes flows, for the rotating brushes 7 and for the motor means 28, 29.

[0050] The ducts 4 are arranged successively in the feeding direction x of the ply 2 .

[0051] Between the ducts 4 for the passage of the flow of cellulose flakes, infeed ducts 26 for the superabsorbent material are positioned, which in some cases may be included in the absorbent core itself.

[0052] The ply 2 is fed in the direction x, is supported by a perforated belt 5 closed into a ring and is rotated by a number of motorized rollers or relay rollers 33 .

[0053] The belt 5 is perforated to allow suction by the hood 6 below.

[0054] 4 to 6, there is shown a collection unit 9 where evenly distributed cellulose flakes are deposited onto the ply 2. As shown in FIG.

[0055] In addition to the assembly frame 34, the accumulation unit 9 comprises a first pair of side walls 9a, 9b parallel to the feeding direction x of the ply 2 and a second pair of side walls 9c, 9d perpendicular to the feeding direction x.

[0056] At least the side walls 9a, 9b, which are parallel to the feeding direction x, are provided with felt sides 30 which create an airtight perimeter along their edges towards the ply.

[0057] The suction hood 6 must allow the collection unit 9 to be placed under reduced pressure; the collection unit 9 must therefore have internal dimensions corresponding to the actual dimensions of the absorbent cores to be produced and must be airtight.

[0058] For this purpose, the forming station 1 comprises adjustment means for adjusting the mutual position of the side walls 9a, 9b parallel to the feed direction x of the ply 2, thereby varying the dimensions of the accumulation unit 9 according to the width of the ply.

[0059] The adjusting means act on both ends of the accumulation unit 9 in the feeding direction x of the ply 2: a stop plate 35, movable and selectively fixable in position by a first handwheel 36, this position predetermining in particular the width dimension of the accumulation unit 9; and a second handwheel 37 adapted to induce the displacement of the side walls 9a, 9b parallel to the feed direction x of the ply 2 along a cam profile 38 realized on the assembly frame 34 until it touches the stop plate 35, and then to fix their mutual position; Equipped with.

[0060] For the purpose of airtightness around the periphery of the accumulation unit 9, each side wall 9c, 9d perpendicular to the infeed direction x is provided with an idle rubber-coated roller 10, which is adapted to roll on the ply 2 (Figure 5).

[0061] The idle rubber-coated roller 10 allows the gathering unit 9 to be closed airtight and at the same time allows the ply 2 to be fed in without risk of tearing.

[0062] The accumulation unit 9 also comprises another sealing system with scraper blades 11, 12; the position of which can be manually adjusted, the blades 11, 12 are adapted to act like scrapers, sliding over the idle rubber-coated roller 10 and creating a seal against the sheet metal forming the assembly frame 34 of the accumulation unit 9 (Figure 6).

[0063] This sealing system is important to ensure good suction of the cellulose flakes and to prevent voids that could create turbulence that would impair the even deposition of the cellulose on the ply 2.

[0064] Referring in detail to Figure 7, the screen 8 has two parts provided with holes 8' for the passage of cellulose flakes and positioned substantially below the duct 4 for feeding cellulose, and a central opening 27 which is directly connected to the feeding duct 26 for feeding superabsorbent material, thereby advantageously serving to deposit the superabsorbent material directly on the ply 2 between the first and second layers of cellulose.

[0065] As the screen 8 moves in alternating parallel motion in the feeding direction of the ply 2, the screen 8 is provided with wheels 16 and the frame 3 is provided with corresponding tracks 15 adapted to cooperate with the wheels 16 (Fig. 3).

[0066] With particular reference to the detailed cross section of FIG. 8, the means for "going back and forth" alternating movement of the screen 8 is shown.

[0067] In particular, the movement means comprises a mechanism with a connecting rod 13 and a crank 14 .

[0068] The connecting rod 13 has a first end 13' and a second end 13''.

[0069] This crank is produced by a wheel 14 to which a first end 13' of a connecting rod 13 is fixed off-center.

[0070] The second end 13'' of the connecting rod 13 is connected to the screen 8 by a first type joint 39 with two arms and a rod 40 with two hinges.

[0071] The articulation 39 is hinged to the frame 3 and has a first end 39' and a second end 39''.

[0072] The first end 39 ′ of the link 39 is connected to the second end 13 ″ of the connecting rod 13 .

[0073] A second end 39'' of the articulation 39 is connected to a first end 40' of the rod 40 by means of two hinges.

[0074] The second end 40 ″ of the rod 40 with the two hinged sections is then connected to the screen 8 .

[0075] In order to adjust the range of the "back and forth" alternating movement of the screen 8, to modify the density of the cellulose deposited in the ply 2 and to take into account the final dimensions of the absorbent core, the crank 14 is provided along its diameter with selective fixing means for the first end 13' of the connecting rod 13.

[0076] This selective fixing means comprises an adjusting screw 41 adapted to be moved along the working diameter of the crank 14: a smaller diameter reduces the range of alternating movement of the screen 8; conversely, a longer diameter provides a wider range of alternating movement.

[0077] 9 to 13, the suction hood 6 is shown positioned below the perforated belt 5 supporting the ply 2. As shown in FIG.

[0078] The suction hood 6 basically comprises an extractor 17 with a horizontal shaft, a horizontal conveyor 18 and a vertical conveyor 19 joined together by a flange 20 .

[0079] The horizontal conveyor 18 is provided with a suction inlet 21 over which the perforated belt 5 travels and on which the ply 2 rests.

[0080] The suction inlet 21 is provided with a blade blocking means for adjusting its opening.

[0081] The blade blocking means comprises two plates 22 sliding on a surface containing a suction inlet 21 transverse to the feeding direction x of the ply 2 .

[0082] The sliding of the plate 22 narrows or widens the suction inlet 21 according to the width of the ply 2 being fed forward.

[0083] The conveyors 18, 19 each include a plurality of interior walls 18', 19' that divide them into a horizontal chamber 23 and a vertical chamber 24.

[0084] Advantageously, the suction hood 6 can also vary its suction flow rate by selectively closing off cross sections of the chambers 23, 24.

[0085] The horizontal and vertical conveyors 18, 19 are provided with shutters 25 which are rotatably connected to the walls 18', 19' by hinges.

[0086] The horizontal conveyor 18 and the vertical conveyor 19 are provided with externally operable control means for the shutters 25 .

[0087] The control means comprises, for each shutter 25: - slots 42 realized in the outer sidewall of each conveyor 18, 19; a control pin 43 associated with the shutter 25, which passes through a slot 42 and projects outside the suction hood 6, sliding inside it; and locking means for locking the selected position of the control pin 43 in the slot 42; Equipped with.

[0088] For each control pin 43, these locking means comprise a pin 44 firmly connected to the same outer side wall of the conveyor 18, 19 in which the slot 42 is realized, and a comb 45 connected to the control pin 43. The teeth of the comb 45 are adapted to cooperate with the pin 44 to maintain the position of the control pin 43 fixed inside the slot 42, thereby fixing and maintaining the inclination of the respective shutter 25 relative to the inner wall 18', 19' of the hinged conveyor 18, 19.

[0089] The operation of forming station 1 is as follows.

[0090] The ply 2 is forced into the forming station 1 in the feed direction x by a suction hood and rests on a perforated belt 5 .

[0091] The cellulose flakes coming from the crushing rolls are blown into the infeed duct 4 .

[0092] The cellulose flakes are urged along by the combined rotational movement of the brush 7 and sucked up by the suction hood 6 .

[0093] As the brushes 7 rotate, they lightly touch the screen 8, entraining the cellulose flakes through the holes 8' in the screen.

[0094] The simultaneous "back and forth" alternating movement of the screens 8 ensures an even distribution of the cellulose on the underlying ply 2.

Claims

1. A forming station (1) for forming absorbent cores of disposable hygiene products of the type comprising at least one ply (2) interspersed with cellulose, comprising: Frame (3), means for feeding cellulose flakes, comprising at least one duct (4) designed to convey a flow of cellulose flakes towards said ply; means for feeding the ply (2) in a feeding direction (x); a perforated belt (5) adapted to support the ply (2) as it is fed forward; and a suction hood (6) positioned below the perforated belt (5) and designed to suck the cellulose and lay it flat on the ply (2); Equipped with wherein the forming station a plurality of horizontal axis rotating brushes (7) arranged transversely to the feeding direction (x) of the ply (2); a screen (8) having a plurality of holes (8') disposed between the plurality of horizontal-axis rotating brushes (7) and the ply (2); means for "back and forth" alternating movement of the screen (8) parallel to the feeding direction (x) of the ply (2); and the horizontal axis rotating brushes (7) are in functional contact with the screen (8) and are designed so that the cellulose flakes pass through the holes (8') of the screen (8) as urged by the suction hood (6) and the combined movement of the horizontal axis rotating brushes (7) and the screen (8); A forming station (1) characterized by:

2. 2. A forming station (1) according to claim 1, characterized in that it comprises a cellulose accumulation unit (9) arranged between the screen (8) and the perforated belt (5) and closed around its periphery so that it can be placed under reduced pressure by the suction hood (6).

3. 3. A forming station (1) according to claim 2, characterized in that the accumulation unit (9) comprises a first pair of side walls (9a, 9b) parallel to the feeding direction (x) of the ply (2) and a second pair of side walls (9c, 9d) perpendicular to the feeding direction (x).

4. 4. A forming station (1) according to claim 3, characterized in that it comprises adjustment means for adjusting the mutual position of the side walls (9a, 9b) parallel to the feeding direction (x) of the ply (2), thereby varying the dimensions of the accumulation unit (9) according to the width of the ply.

5. 4. A forming station (1) according to claim 3, characterized in that each side wall (9c, 9d) perpendicular to the feeding direction (x) is provided with a roller (10) designed to rest on the plies (2) to seal the accumulation unit (9) and allow the plies to be fed forward.

6. 6. A forming station (1) according to claim 5, characterized in that the collecting unit (9) comprises a sealing system with scraper blades (11, 12) positioned on each roller (10).

7. 2. Forming station (1) according to claim 1, characterized in that the means for "back and forth" alternating movement of the screen (8) comprise at least a connecting rod (13) and a crank (14) mechanism.

8. 8. A forming station (1) according to claim 7, characterized in that the crank (14) is made of a wheel (14) provided with selective fixing means for the connecting rod (13) along its radial direction in order to adjust the range of the alternating "back and forth" movement of the screen (8).

9. 2. A forming station (1) according to claim 1, characterized in that the frame (3) comprises a track (15) and the screen (8) comprises wheels (16) designed to cooperate with the track (15).

10. 2. A forming station (1) according to claim 1, characterized in that the suction hood (6) comprises an extractor (17), a horizontal conveyor (18) and a vertical conveyor (19), joined together by flanges (20).

11. 11. A forming station (1) according to claim 10, characterized in that the horizontal conveyor (18) comprises a suction inlet (21) over which the perforated belt (5) travels, the ply (2) resting on the perforated belt (5), and the suction inlet (21) comprises blade blocking means (22) for adjusting its opening.

12. 11. The forming station (1) according to claim 10, characterized in that the horizontal conveyor (18) and the vertical conveyor (19) each comprise a plurality of internal walls (18', 19') dividing them into horizontal chambers (23) and vertical chambers (24), respectively.

13. 13. The forming station (1) according to claim 12, characterized in that the horizontal conveyor (18) and the vertical conveyor (19) are provided with shutters (25) designed to regulate the suction flow rates of the horizontal chamber (23) and the vertical chamber (24).

14. 14. A forming station (1) according to claim 13, characterized in that the horizontal conveyor (18) and the vertical conveyor (19) are provided with externally operable control means for the shutters (25).

15. 2. A forming station (1) according to claim 1, characterized in that the cellulose flake feeding means comprise two ducts (4) arranged successively in the feeding direction (x) of the ply (2), and a feeding duct (26) for feeding superabsorbent material is interposed between said ducts (4).

16. 17. The forming station (1) according to claim 16, characterized in that the screen (8) has a central opening (27) directly connected to the infeed duct (26) for feeding the superabsorbent material, thereby serving to favor the direct deposition of the superabsorbent material between the first and second layers of cellulose flakes.

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