APPARATUS AND METHOD FOR FORMING AN ABSORBENT PAD

Abstract

An apparatus for forming an absorbent pad for an absorbent sanitary article including a first layer, a second layer and an absorbent material interposed between the first and the second layer, includes: a forming drum; a first feed system for feeding to the forming drum a first web, intended to form the first layer; and a second feed system for feeding to the forming drum a second web, intended to form the second layer; at least one spreader for spreading the absorbent material on the forming drum; the first web, the second web and the absorbent material together form a composite web and the forming apparatus includes a system for joining the first and second webs and a system for calibrating the thickness of the absorbent material in the composite web and being located upstream of the joining system in a feed direction V of the composite web.

Claims

1. An apparatus for forming an absorbent pad for an absorbent sanitary article, the pad comprising a first layer, a second layer and an absorbent material interposed between the first and the second layer and arranged according to an absorbent material spreading pattern M1 having at least one channel (104, 105) which is free of absorbent material, the first and second layers being joined to each other along a first and a second longitudinal edge, along a first and a second transverse edge and at the channel, the apparatus comprising a forming drum, a first feed system for feeding to the forming drum a first web, intended to form the first layer, a second feed system for feeding to the forming drum a second web, intended to form the second layer, at least one spreader for spreading the absorbent material on the forming drum, the forming drum comprising a suction system to create on the first web disposed on the forming drum a spread of absorbent material according to the absorbent material spreading pattern M1, the forming drum comprising at least one insert in the suction system to inhibit suction at the channel, the absorbent material not being retained at the insert, the first web, the second web and the absorbent material together forming a composite web, the apparatus comprising a system for joining the first and second webs at least at the channel and located downstream of the second feed system, the apparatus being characterized in that it comprises a system for calibrating the thickness of the absorbent material in the composite web, the calibrating system being located upstream of the joining system in a feed direction V of the composite web.

2. The apparatus according to claim 1, wherein the calibrating device comprises a first roller, having an axis of rotation R21, and a second roller, having an axis of rotation R22 parallel to the axis of rotation R21, a first outside surface of the first roller and a second outside surface of the second roller delimiting a through slit for the passage of the composite web, the slit having a size d which is fixed in a radial direction common to the first and second rollers and corresponding substantially to a preferred thickness of the pad.

3. The apparatus according to claim 2, wherein the first outside surface is a right-angled cylindrical surface whose axis is R21.

4. The apparatus according to claim 2, wherein the second outside surface is a right-angled cylindrical whose axis is R22.

5. The apparatus according claim 2, wherein the first and second rollers (21, 22) extend widthways along the axes R21 and R22 at least as much as the composite web does.

6. The apparatus according to claim 1, comprising a pressing device for pressing the composite web along the first and second longitudinal edges, the pressing device being located downstream of the second feed system in the feed direction V of the composite web.

7. The apparatus according to claim 6, wherein the pressing device is located downstream of the calibrating system in the feed direction V of the composite web.

8. The apparatus according to claim 6, wherein the pressing device is located upstream of the joining system.

9. The apparatus according to claim 6, wherein the pressing devices comprises a third roller having an axis of rotation R25 and an opposing member for contacting an outside surface of the third roller, the outside surface of the third roller having an annular grooved which delimits a first and a second annular tooth (28, 29) axially spaced from each other and intended to engage the composite web along the first and second longitudinal edges of the absorbent pads following each other consecutively in the composite web, the composite web, in use, passing in between the third roller and the opposing member.

10. The apparatus according to claim 9, wherein the opposing member is a fourth roller having an axis of rotation R26 parallel to the axis of rotation R25 and having a cylindrical outside surface defining with the outside surface of the third roller a passage for the composite web.

11. The apparatus according to claim 1, wherein the calibrating system comprises a pressing device for pressing the composite web along the first and second longitudinal edges, the pressing device being located downstream of the second feed system in the feed direction V of the composite web.

12. The apparatus according to claim 1, comprising a systems for removing any absorbent material there may be on the first web at the insert, the removal system being located downstream of the absorbent material spreader in the feed direction V1 of the first web, the system for removing the absorbent material being operative on the forming drum and comprising a blowing system for blowing away any absorbent material there may be on the first web at the insert.

13. A method for forming an absorbent pad for an absorbent sanitary article, the pad comprising a first layer, a second layer and an absorbent material interposed between the first and the second layer and arranged according to a spreading pattern M1 having at least one channel which is free of absorbent material, the method comprising a step of feeding a first web, intended to form the first layer, a step of feeding a second web, intended to form the second layer, a step of spreading the absorbent material on the first web according to the spreading pattern M1, a step of joining the first and second webs, the first web, the second web and the absorbent material together forming a composite web, the method being characterized in that it comprises a step of calibrating the thickness of the absorbent material in the composite web.

14. The method according to claim 13, wherein the step of calibrating comprises a step of squeezing the composite web to give the composite web a uniform thickness.

15. The method according to claim 14, wherein the step of squeezing is carried out across the full width of the composite web.

16. The method according to claim 13, wherein the step of calibrating the composite web comprises feeding the composite web through a slit of predetermined height d which is less than or equal to the desired thickness of the composite web.

17. The method according to claim 13, comprising a step of pressing the composite web along the first and second longitudinal edges of the pad.

18. The method according to claim 17, wherein the step of pressing the composite web is carried out after the step of calibrating the thickness of the absorbent material in the composite web.

19. The method according to claim 17, wherein the step of pressing the composite web is carried out simultaneously with the step of calibrating the thickness of the absorbent material in the composite web.

20. The method according to claim 13, comprising a step of removing any absorbent material there may be on the first web at the channel, the step of removing comprising a step of blowing away any absorbent material there may be on the first web at the channel.

21. The method according to claim 20, wherein blowing is intermittent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Further characteristics and advantages of this solution are more apparent in the non-limiting description below, with reference to a preferred but non-exclusive embodiment of a method and an apparatus for forming a pad, as illustrated in the accompanying drawings, in which:

[0088] FIG. 1 is a schematic top plan view of an absorbent pad made by an apparatus according to this disclosure;

[0089] FIG. 2 is a schematic front view of a forming apparatus according to this disclosure for forming an absorbent pad;

[0090] FIG. 3 illustrates the apparatus of FIG. 1 in a schematic side view, partly in blocks and with some parts cut away for greater clarity;

[0091] FIG. 4 shows a detail of the apparatus of FIG. 1 in a schematic side view and with some parts cut away for clarity;

[0092] FIG. 5 shows a detail of the apparatus of FIG. 1 in a schematic side view and with some parts cut away for clarity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0093] With reference to FIG. 1, the numeral 100 denotes a pad obtainable with a forming apparatus made in accordance with this disclosure.

[0094] The pad 100, intended for use in absorbent sanitary articles such as nappies for children or adults, for example, comprises a first layer 101, a second layer 102 and an absorbent material 103 interposed between the first and the second layer 101, 102 and arranged according to a spreading pattern M1.

[0095] The first and second layers 101, 102 are made, for example, of non-woven fabric and are joined to each other; the absorbent material 103 comprises, for example, cellulose fibres and superabsorbent material, also called SAP, and is fixed between the first and the second layer 101, 102.

[0096] In the example illustrated, the pattern M1, and hence the pad 100, has two zones or channels 104, 105 which are free of absorbent material and where the first and second layers 101, 102 are joined directly to each other.

[0097] In the preferred embodiment illustrated by way of example, the pad 100 has a first and a second longitudinal edge 106, 107 along which the first and second layers 101, 102 are joined directly to each other, for example by adhesive and/or by welding.

[0098] In the preferred embodiment illustrated by way of example, the pad 100 has a first and a second transverse edge 108, 109 along which the first and second layers 101, 102 are joined directly to each other, for example by adhesive and/or by welding.

[0099] With reference to FIGS. 2 and 3, the numeral 1 denotes a forming apparatus for forming the pad 100 made in accordance with this disclosure.

[0100] This description of the apparatus 1 is limited to the parts necessary for understanding this disclosure.

[0101] The apparatus 1 comprises a drum 2 for forming the pads 100 and rotatable about an axis R2.

[0102] Along its periphery, the drum 2 comprises a plurality of seats 3, in particular for receiving the material 103, as described in more detail below.

[0103] The apparatus 1 comprises a first feed system, schematically represented as a block 4, for feeding a first web NW1 to the forming drum 2.

[0104] The web NW1 is movable in a direction V1 and is intended to form the first layer 101 of the pad 100.

[0105] The apparatus 1 comprises a second feed system, schematically represented as a block 5, for feeding a second web NW2 to the forming drum 2.

[0106] The web NW2 is movable in a direction V2 and is intended to form the second layer 102 of the pad 100.

[0107] The apparatus 1 comprises a spreader 6 for spreading the absorbent material 103 on the forming drum 2; the spreader 6 is of a substantially known type and is not described further.

[0108] The first web NW1, the second web NW2 and the absorbent material 103 together form a composite web NW which is movable in a direction V.

[0109] The forming drum 2 comprises a suction system 7, schematically represented as a block, to create on the first web NW1 fed by the drum 2, a spread of absorbent material according to the absorbent material spreading pattern M1.

[0110] More specifically, the suction system 7 is in communication with the seats 3 which, in practice, are preferably suction tiles and which hold the material 103 at a predetermined position relative to the web NW1, which is also held partly on the drum 2 by suction, according to the pattern M1.

[0111] The material 103 is positioned on the suction tiles which, in an embodiment not illustrated, may be in the form of a continuous circular seat extending along a substantially cylindrical peripheral portion of the drum 2.

[0112] In another embodiment, of the type illustrated in the drawings, the suction tiles may be in the form of a plurality of discrete seats 3, aligned and equispaced along a substantially cylindrical peripheral portion of the drum 2.

[0113] The seats 3 may in any case be shaped to match the pad 100 and are capable of retaining by suction the absorbent material 103 transported by the drum 2.

[0114] As may be observed in particular in FIG. 3, the forming drum 2 comprises a plurality of inserts 8 in the suction system 7, positioned in particular in the seats 3, to inhibit suction at the channels 104 and 105 to be formed in the pads 100.

[0115] That way, the absorbent material 103 is not held on the web NW1 where the inserts 8 are and hence, where the channels 104, 105 will be formed.

[0116] In the preferred embodiment illustrated, the forming apparatus comprises an adhesive dispenser 9 located upstream of the spreader 6 of the absorbent material in the feed direction V1 to apply on the first web NW1 a layer of adhesive according to a pattern M2 for gluing the absorbent material 103.

[0117] In a preferred embodiment, the gluing pattern M2 corresponds to the absorbent material pattern M1, that is to say, the adhesive is applied on the web NW1 in the zones where the absorbent material 103 is to be deposited.

[0118] More specifically, the gluing pattern M2 comprises zones Z1, Z2 which are free of adhesive, corresponding to the channels 104, 105.

[0119] A preferred embodiment of the apparatus 1 comprises a welding system 10 to join the first and second webs NW1, NW2 according to a welding pattern M3.

[0120] In the preferred embodiment illustrated by way of example, the apparatus 1 comprises a welding system 10 to join the first and second webs NW1 and NW2 according to a welding pattern M3 and a welding system 11 to join the first and second webs NW1 and NW2 according to a welding pattern M4.

[0121] The systems 10 and 11 are used to weld pads 100 of different sizes and operate alternatively, that is to say, when the system 10 is operating, the web NW passes through the system 11 in transit only, and vice versa.

[0122] Preferably, the apparatus 1 comprises an ultrasonic welding system 10, 11.

[0123] The systems 10 and 11 each comprise a first welding element 12, 13 which, in the example illustrated, is defined by a welding roller rotatable about a respective axis of rotation R12, R13.

[0124] The systems 10 and 11 each comprise a second welding element 14, 15 which, in the example illustrated, is defined by a sonotrode.

[0125] The rollers 12 and 13 each define, for the respective sonotrodes, a welding anvil.

[0126] Each first welding element 12, 13 has an opposing surface for contact with the respective second welding element and shaped according to the respective welding pattern M3, M4.

[0127] The welding roller 12 with the respective welding pattern M3 is illustrated by way of an example in FIG. 3; the pattern M4 is conceptually identical to the pattern M3 and is therefore not described further.

[0128] The welding roller 12 has an opposing surface 12a for contact with the sonotrode 14 and shaped according to the respective welding pattern M3.

[0129] The pattern M3 comprises a welding zone Z3, Z4 corresponding to the channels 104, 105.

[0130] In practice, the surface 12a is shaped to define an anvil for the sonotrode 14 in the zones Z3, Z4 corresponding to the channels 104 and 105.

[0131] In a preferred embodiment of the apparatus 1, the pattern M3 comprises a welding zone Z5, Z6 at the longitudinal edges 106, 107 of the pad 100.

[0132] In practice, the surface 12a is shaped to define an anvil for the sonotrode 14 in the zones Z5, Z6 corresponding to the longitudinal edges 106 and 107 of the pad 100.

[0133] In an embodiment not illustrated, the pattern M3 comprises a welding zone Z7, Z8 at the transverse edges 108, 109 of the pad 100.

[0134] In practice, the surface 12a is shaped to define an anvil for the sonotrode 14 in the zones Z7, Z8 corresponding to the transverse edges 108 and 109 of the pad 100.

[0135] In an embodiment not illustrated, the welding roller, that is, the first welding element of the welding system 10, is the forming roller 2.

[0136] In such a case, the forming roller 2, which in the case of ultrasonic welding, constitutes the anvil of the system, comprises a respective opposing surface for contact with the sonotrode and shaped, for example, according to the welding pattern M3.

[0137] In the embodiment illustrated by way of example, the apparatus 1 comprises a second adhesive dispenser 16 for applying a layer of adhesive on the web NW2 in order to optimize to the first web NW1.

[0138] The adhesive delivered by the dispenser 16 can cause the web NW2 to adhere to the web NW1, joining them together to form the composite web.

[0139] According to one aspect of this disclosure, the apparatus 1 comprises a removal system 17 for removing any absorbent material that may be present on the first web NW1 at the inserts 8, that is, in the zones of the web which will constitute the channels 104, 105.

[0140] The system 17 operates at the forming drum 2 and is mounted downstream of the spreader 6 of the absorbent material 103 in the feed direction V1 of the first web NW1.

[0141] In the embodiment illustrated by way of example, the removal system 17 for removing the absorbent material comprises a blowing system 18 which can blow away from the web NW1 any absorbent material 103 that may be present at the inserts 8, that is, at the channels 104 and 105. The material 103 may be blown onto the suction zones, where it is retained by the system 7.

[0142] In the embodiment illustrated, the blowing system 18 comprises at least one centrifugal impeller 19 whose axis of rotation R19 is parallel to the axis of rotation R2 of the drum 2.

[0143] In the example illustrated, the system comprises two coaxial impellers 19, each disposed at a respective channel 104, 105.

[0144] As illustrated schematically in FIG. 2, the impellers 19 have an outside surface which faces the drum 2.

[0145] According to one aspect of the disclosure, the impellers 19 generate a vortex at the inserts 8 which forces any absorbent material 103 that may be present there towards negative pressure zones of the drum 2.

[0146] In alternative embodiments, the blowing system comprises nozzles which blow air at the inserts 8; the nozzles are preferably directed towards the forming drum 2.

[0147] Preferably, the impellers 19, or the blowing nozzles, are disposed along the trajectories T1, T2 followed by the inserts 8 as the drum 2 rotates about the axis R2.

[0148] The impellers 19, or the blowing nozzles, are also optimized to prevent the blown air from modifying the pattern of the absorbent material 103 spread near the channels.

[0149] In alternative embodiments not illustrated, the removal system 17 for removing the absorbent material may, for example, comprise brushes acting on the web NW1 and/or a suction system for extracting the absorbent material and/or a scraper to ensure that the web NW1 remains clean at the channels 104, 105 where it will be welded.

[0150] As may be observed in particular in FIGS. 2 and 4, the apparatus 1 in the preferred embodiment illustrated, comprises a calibrating system 20 for calibrating the thickness of the absorbent material in the composite web NW.

[0151] The calibrating system 20 is preferably located upstream of the welding system 10, 11 in the feed direction V of the composite web NW.

[0152] As illustrated, the calibrating system 20 is located downstream of the second feed system 5 which feeds the second web NW2.

[0153] The calibrating device illustrated by way of an example, comprises a first roller 21 having an axis of rotation R21 and a second roller 22 having an axis of rotation R22 which is parallel to the axis of rotation R21.

[0154] The axes R21 and R22 are preferably also parallel to the axis R2.

[0155] A first outside surface 21a of the first roller and a second outside surface 22a of the second roller delimit a slit 23 for the passage of the composite web NW.

[0156] The width d of the slit 23 is fixed at least in a radial direction common to the first and the second roller 21 and 22.

[0157] The width or height d of the slit 23 substantially corresponds to a preferred thickness of the absorbent pad 100.

[0158] In the preferred embodiment illustrated, the outside surface of the first roller 21 is a right-angled cylindrical surface having an axis R21 and the outside surface 22a of the second roller 22 is a right-angled cylindrical surface having an axis R22.

[0159] Preferably, the first and second rollers 21 and 22 of the calibrating system 20 extend in width along the axes R21 and R22 at least as much as the composite web NW does so as to be able to squeeze the composite web along its full width.

[0160] As may be observed in FIGS. 2 and 5, the apparatus 1 in the preferred embodiment illustrated, comprises a pressing device 24 for pressing the composite web NW along the first and second longitudinal edges 106, 107 of the pads 100.

[0161] The device 24 is located downstream of the calibrating system 20 in the feed direction V of the composite web NW.

[0162] In the preferred embodiment illustrated, the device 24 is located upstream of the welding system 10, 11 of the first and second webs NW1, NW2.

[0163] As illustrated by way of example, the device 24 comprises a third roller 25 having an axis of rotation R25 and an opposing member 26 in contact with an outside surface 25a of the roller 25.

[0164] The surface 25a preferably has an annular groove 27 delimiting a first and a second annular tooth 28, 29 which are axially spaced and intended to engage the composite web NW along the first and second longitudinal edges 106, 107 of the successive absorbent pads 100 making up the composite web NW.

[0165] In the preferred embodiment illustrated, the opposing member 26 is a fourth roller having an axis of rotation R26 parallel to the axis of rotation R25 and having a cylindrical outside surface 26a defining with the outside surface 25a of the third roller a passage 30 for the composite web.

[0166] In alternative embodiments not illustrated, the opposing member 26 may be a flat surface on which the web NW is fed.

[0167] In an alternative embodiment not illustrated, the calibrating system 20 comprises the pressing device 24 for pressing the composite web NW along the first and second longitudinal edges 106, 107 of the pad.

[0168] The pressing device 24 is located downstream of the feed system 5 for feeding the second web NW2 in the feed direction V of the composite web NW.

[0169] This alternative embodiment may be, for example, like the device illustrated in FIG. 5, where the depth of the groove 27, measured in the radial direction, corresponds to the width or height d.

[0170] A method for forming an absorbent pad 100 according to this disclosure comprises a step of feeding to the forming drum 2 the first web NW1, intended to form the first layer 101, a step of feeding to the forming drum 2 the second web NW2, intended to form the second layer 102, a step of spreading the absorbent material 103 on the first web NW1 according to the spreading pattern M1 and a step of spreading adhesive on the first web NW1 according to the gluing pattern M2.

[0171] The method comprises a step of joining together the webs NW1 and NW2, preferably by welding.

[0172] Welding the first and second webs NW1, NW2, for example ultrasonic welding, according to the welding pattern M3 or M4, which comprises the welding zones Z3, Z4 at the channels 104, 105, contributes to the formation of the composite web NW.

[0173] The method comprises a step of calibrating the thickness of the absorbent material 103 in the composite web NW.

[0174] Preferably, the step of calibrating comprises a step of squeezing the composite web NW to give the composite web NW a substantially uniform thickness or to evenly spread the absorbent material 103 inside it.

[0175] The step of squeezing, which is preferably carried out across the full width of the composite web NW, is accomplished by feeding the composite web through the slit 23.

[0176] This method comprises a step of pressing the composite web NW along the first and second longitudinal edges 106, 107 of the pads 100 which, in practice, make up the composite web NW.

[0177] In an embodiment, the step of pressing the composite web NW is carried out simultaneously with the step of calibrating the thickness of the absorbent material 103 in the composite web NW.

[0178] In practice, while the absorbent material is being squeezed to eliminate any lumps, the longitudinal edges of the pads are also squeezed simultaneously as the composite web is fed between a pair of suitably shaped rollers.

[0179] The method comprises a step of removing any absorbent material 103 that may be present on the web NW1 in the welding zones Z3, Z4 where the channels 104, 105 will be defined.

[0180] In a preferred embodiment, illustrated by way of example, the step of removing the absorbent material 103 comprises a step of blowing away from the web NW1 any absorbent material 103 that may be present in the welding zones Z3, Z4 at the channels 104, 105 in order to clean the web so it is ready for subsequent welding.

[0181] Since the channels 104, 105 are not continuous along the composite web NW, and hence the zones 104, 105 free of absorbent material on the web NW1 are not continuous, the step of blowing can be intermittent.