US20160068364A1

US20160068364A1 - Separating and folding web materials cross-directionally

Info

Publication number: US20160068364A1
Application number: US14/783,206
Authority: US
Inventors: Christoph Schmitz
Original assignee: Concepts for Success C4S
Current assignee: Concepts for Success C4S
Priority date: 2013-03-01
Filing date: 2014-02-27
Publication date: 2016-03-10
Also published as: GB2526498A; GB201303722D0; WO2014131813A1; GB2514532A; GB2526498B; GB201517212D0

Abstract

The present invention relates to a novel equipment and a manufacturing process for separating a series of web pieces from an essentially continuous web and essentially concurrently forming an overfold along a cross-directionally extending fold line. The separating and overfolding may very advantageously be applied in the manufacturing of articles to be worn on the lower torso of a wearer, such as disposable absorbent articles, or disposable underwear.

Description

FIELD OF THE INVENTION

The present invention relates to a method and equipment for the cross-directionally folding and separating of web materials, such as essentially continuous webs of plastic films, textiles, non-wovens, or papers, or the like or composites made from such web materials.

BACKGROUND

Separating pieces form an essentially continuous web material has since long been a challenge in a number of industry sectors, such as the textile sector, the hygiene or medical sectors, the packaging sectors, or the bookbinding/printing sectors.
In all such sectors, it is desirable to produce at high production speeds, and henceforth also high transfer speeds of the webs, however, it should be noted that the presently applied techniques of folding parts or pieces of a web rely generally on a free movement of at least one edge of the web material (such as the leading edge, or the folding edge, or both the leading and trailing edges of pieces arte cut off of a continuous web), see e.g. US-B-6669618 (P&G, Molander), where e.g. a disposable diaper is separated from an essentially endless material and CD-folded and the end sections of the article are folded one on the other and connected to each other by means of a slot and tab fastener system. Any free movement of a leading and/or trailing edge(s), however, has the risk of inducing large variations with regard to positioning, and this risk increases strongly with increasing production speed, particularly if the endless web includes materials which are stretched and contractive in the machine direction of the manufacturing unit.
The underlying reason for these variations is in the fact that cutting and folding are generally done subsequently, i.e. by machine components which are positioned at a machine directional distance to each other. The trailing edge of a piece (n) cut off a continuous web by a conventional crush cutter is untensioned and hence moving freely and uncontrolled through the cutting unit until also the trailing section of the piece has left (“cleared”) the cutter completely, and the piece is received by a further web support unit positioned downstream. The same applies to the leading edge of the subsequent piece of web material (n+1).
When combining the separation of pieces of web material from a continuous web material with cross-directional folding of the pieces, typical conventional folding units have the disadvantage that they need to instantaneously revert the direction of movement of the leading section of a product such that it's leading and trailing edges can be positioned against each other. This sudden change in direction of movement cannot be done without putting stress on the product with a high risk of imprecise positioning if not damaging it, particularly at high production speeds. The difficulties of handling such web materials are further aggravated, if the webs comprise machine-directionally elastically extended materials, such as elastic threads.
EP-0717972A (P&G, Schmitz) describes a method of making an undergarment which comprises the steps of transporting a flattened web, cutting the web to form a pre-form, gripping the pre-form at four areas of the waist sections near seal areas, turning the grippers to bring the transverse edges together and releasing the article. Also described is an apparatus having a folding and sealing unit and comprising two hinged carrier arms, grippers attached to the carrier arms and carrier arm rotation means. Preferably the grippers are rotated to bring the transverse edges together. The web may include film and nonwoven materials, and an absorbent core so as to form a disposable absorbent article.
The present invention provides a simple solution to the problem of folding a web in its cross-machine direction and separating it from its continuous supply simultaneously.

SUMMARY

In a first aspect, the present invention is a method for forming a series (n, n+1, . . . ) of overfolded pieces of web material from an essentially endless web material, each piece comprising a first and a second end section and a middle section positioned there between and comprising a cross-directionally extending fold line such that the first and the second section are at least partially lying upon another. The method comprising the steps of

- a) providing an essentially continuous supply of a web material along a web path defining a downstream machine direction away from the web supply;
- b) providing a folding and separating unit comprising
  - b1) a web inlet;
  - b2) a folder web support means;
  - b3) a web holding means;
  - b4) a web separating means.
  - Therein, (b5) the folder web support means is positioned downstream of the web inlet, separated by an inlet gap there from and (b6) the web holding means is moveably mounted such that it can move around the folder web support means from a position downstream of the folder web support means to a position in the inlet gap, wherein the movement is preferably rotational, more preferably circular, around an axis perpendicular to the machine direction.
- The method comprises further the steps of:
  - c) feeding a leading end of the essentially continuous web from the web supply through the web inlet over the inlet gap towards the folder web support means;
  - d) affixing the leading end of the essentially continuous web temporarily on the folder web support means and moving it machine directionally downstream;
  - e) adjusting the movement of the web holding means around the folder web support means such that the web holding means is positioned downstream of the folder web support means when the leading end of the continuous web is released from the folder web support means whilst continuing to move along the machine direction downstream, such that the leading end contacts the web holding means and is temporarily affixed thereto, optionally by actuating a holding force;
  - f) moving the web holding means with the leading end affixed thereto towards the inlet gap, thereby forming a cross-directional overfold in the web;
  - g) essentially concurrently
    - g1) positioning the leading end over a downstream region of the web and g2) separating a piece of web material from the essentially continuous web, and
    - g3) releasing the piece of web material from the web holding means,
  - such that
    - g4) a new leading end (n+1) is formed and
    - g5) the original leading end (n) now forms the first end section of the piece of web material overlying the second end of the web piece formed by the trailing end as being separated from the new leading end (n+1), whilst the cross-directional fold is positioned in the middle section thereof;
    - h) removing the web holding means from the inlet gap and allowing the new leading end (n+1) to move through the inlet gap to the folder web support means;
  - and repeating steps d) to h), whereby in course of step d) the overfolded piece of web material (n) is removed from the folding and separating unit, preferably machine directionally downstream without interacting with the holding unit.

The separating means may be selected from the group consisting of a knife blade counteracting with another blade, preferably self-sharpening; a knife blade counteracting against an anvil; a water jet system; a radiation technique, preferably laser cutting or plasma cutting; and sonic, preferably ultrasonic, cutting.
The web separating means and the web holding means may be essentially unitary or operatively connected to each other such that both travel around the web folding means according to steps e), f) and h). The separating means may be a rotating knife blade counteracting with a counter-blade, wherein the rotating knife blade is rotating around an axis essentially parallel to the machine direction of the unit, and wherein the counter-blade is positioned in the web inlet.
The leading end of the web may be temporarily attached to the web holding means by one or more attachment means selected from the group consisting of vacuum, mechanical engagement of the “hook-loop-type”, mechanical engagement by protruding pins, optionally moveable pins, with vacuum holding and actuation thereof being preferred.
The overfolding of the web may be executed such that cross-directionally extending edges of the first and the second section of the piece of web material exhibit a machine-directional off-set of less than 25 mm, preferably less than 5 mm, more preferably less than 2 mm and most preferably essentially zero. The distance, that a trailing end edge of a second section of a piece of web material travels before it is positioned adjacent to the first section of the piece of web material may be less than less than 25 mm, preferably less than 5 mm, more preferably less than 2 mm along the machine direction.
The method according to the present invention may further comprise one or more of the following steps:
z) providing a first web transfer means and transferring the essentially continuous web to the folding and separation unit;
y) providing a second web transfer means and removing the overfolded pieces of the web material downstream of the folder web support means;
x) providing a third web transfer mans, optionally movable relative to the folder web support means, preferably translatorily moveable, and removing the overfolded pieces of the web material, whereby the third web transfer means is adapted to make a first contact to the pieces of the web material whilst these are in contact with the folder web support means;
w) providing a bonding means, preferably selected from the group consisting of adhesive application, connecting of mechanical fastening elements of the hook and loop type, heat or fusion bonding comprising ultra sonic bonding, downstream of the holding web support means, optionally cooperatively connected with at least one of the second or third web transfer means, and bonding overlying portions of the piece of web material, preferably at least along or in proximity of at least a portion of the longitudinally extending side margins of the piece of web material;
v) varying the speed of movement of the web holding means for adjusting the predetermined overall length of the piece of web material;
u) providing a folding means to fold pieces of a fastening means, e.g. a hook/loop type fastener which is fixed to and extending over the lateral side margins of the first or second end section of the piece of web material, around a longitudinal foldline such that it engages with the respective other end section.
In a second aspect, the present invention relates to an apparatus for forming a series (n, n+1, . . . )
of overfolded pieces of web material from an essentially endless web material supplied by web supply means, each piece comprising a first and a second end section and a middle section positioned there between, thereby defining the longitudinal direction of the pieces, and comprising a cross-directionally extending fold line such that the first and the second section are at least partially lying upon another. The apparatus comprises a folding and separating unit, which is positioned downstream of the web supply unit and comprises

- 1) a web inlet for feeding an essentially continuous web material to the folding and separating unit;
- 2) a folder web support means, preferably a vacuum belt system, positioned downstream of the web inlet, expanding along the machine direction (x-direction) and exhibiting a cross-machine extension (y-direction) aligned with the cross-direction of the piece of web material, and a height (z-directional) extension;
- 3) a web holding means adapted to receive and temporarily hold a section of the web material;
- 4) a web separating means adapted to separate a piece of web material from the essentially continuous web material.

The web holding means is moveably mounted, preferably rotatably mounted, to allow cyclic movement around the folder web support means with the web being temporarily attached thereto along a movement path forming an essentially x-z-directionally extending plane, preferably a circular, an elliptic or an oval path, for positioning the first section of the web material piece onto the second section of the web material and for forming a cross-directional fold in the middle section of the web material or piece thereof.
The web separating means may be cooperatively connected to the web holding means or has its cyclic operation controlled by or is operated in registry with the cyclic movement of the web holding means.
The web support means and web holding unit may be set in motion by one or more drive systems, preferably selected from the group consisting of drive belts, gear wheels, electrical drive motors, optionally servo drives, the drive systems optionally being controlled by a common control system.
The folder web support means may be operated at constant speed whilst the web holding unit may travel at a cyclic speed pattern, preferably a sinusoidal pattern around the folder web support means.
Preferably, a gap formed between the web inlet and the folder web support is smaller than 20 cm, preferably smaller than 10 cm, more preferably smaller than 5 cm.
The separating means may be selected from the group consisting of

- a knife blade counteracting with another blade, preferably self-sharpening;
- a knife blade counteracting against an anvil;
- a water jet system;
- a radiation technique, preferably laser cutting or plasma cutting;
- sonic, preferably ultrasonic, cutting.

The separating unit may comprise a cross-directionally extending knife blade rotatably mounted to rotate around an axis of rotation which is essentially parallel to the machine direction.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 A and B show schematically a folding and separating unit in a side and top view

FIG. 2 A to F depict schematically the process steps for folding and separating a web.

FIG. 3 is used to explain the effect of varying speed of the holding and separating element.

FIG. 4 A to F depict schematically a specific execution of a folding and separating unit)

FIG. 5 depicts schematically another specific execution of a folding and separating unit

FIG. 6 A to D show schematically a specific execution for a separation unit.

FIG. 7 A depicts schematically specific positioning of the web material according to the present invention.

FIG. 7B depicts schematically a prior art execution of separating and folding web materials.

FIG. 8 A and B depict schematically a web holding unit with particular elements according to the present invention.

Same numerals refer to same or equivalent features.

DETAILED DESCRIPTION

The present invention is concerned with separating and folding webs in a very controlled manner.
Generally, the term “web” relates to any material which is essentially endless or continuous in one direction which is generally denoted as “x-direction” or “machine direction”. In this direction, the web materials move from an “upstream” position (e.g. the web supply) along the web path in a “downstream” position. Webs are often, but not necessarily, stored, supplied or used in roll form and thusly also sometimes denoted “roll goods”. Whilst these are then not “endless” in the strict sense of the word, their extension in this x-direction is significantly larger than in any other direction. By combining consecutive rolls or other batches, (“splicing”) such webs can be considered “endless” for all practical purposes. Webs may be transported in a “batch” form, such as when a roll thereof is shipped, or they may follow a “web path”, such as when the webs are unwound from a roll, as described hereinafter.
Often, but not necessarily, webs have an essentially uniform thickness (herein denoted as “z-direction”, and also constant width (herein denoted as “y-direction”) along the x-directional length. Webs may be of essentially uniform composition, they can be mixtures of materials, they can be composites of materials such as being layered (different materials arranged in a juxtaposed position in the z-direction) and/or can comprise stripes of different materials or materials having different or varying properties (i.e. arranged in a juxtaposed position in the y-direction). Further, webs may be composite webs, such as multilayer webs, or webs to which other elements, such as discrete elements, such as absorbent cores, may be attached. Webs may be folded along longitudinally extending fold lines, such as when two halves of a web are laid onto each other along a longitudinal fold line, or when the longitudinally extending side margins are overfolded towards the centre line.
Typical examples for webs are—without implying any limitation—plastic films or foils, textiles, non-wovens, nets, scrims, paper, or cartons.
Web materials need to satisfy certain requirements relating their intended use, but they should further satisfy certain properties to allow or ease handling. Thus, webs should have a certain minimum integrity as well as bendability or flexibility, so as to allow handling. Webs may also need to satisfy certain properties to allow transportation thereof, such as certain minimum or maximum friction properties, porosities (i.e. resistance to fluids like gases when passing through), or electrostatic properties. Although any material does exhibit a certain inherent elasticity, webs are often referred to as “inelastic”, when they are not intended to return to essentially their original dimensions after being significantly extended. Webs to which the present invention may suitably be applied may be both elastic and inelastic, whereby particular advantages can be exploited in comparison to conventional methods or machines, when the webs comprise machine directionally extended elastic materials.
The present invention relates to folding such webs respectively pieces thereof along a cross- or y-directionally extending fold line. Thus, when considering the movement of such a web respectively its pieces along the machine direction, there will be an original leading end with the downstream end of the web or the piece. Upon folding the web or piece thereof along a cross-directionally extending foldline, this originally leading end will be positioned onto portions of the web or piece positioned more upstream, and the fold line will now mark the post-folding leading end.
Typically, though not necessarily, the continuous web material is supplied at a steady web speed, relative to which other speeds may vary, as will be discussed in more detail hereinafter. Of course, the web material speed does not necessarily need to be constant over time, but still can serve as the reference speed for other process steps to take place. Similarly, the speed of the web may vary over the path, e.g. when an elastic material is extended along this path. In such a situation, the reference speed refers to the web speed at the moment when a web piece is separated there from.
Within the present context, the term “separation” refers to providing individual pieces of a web material by separating these from an essentially endless supply of web material. Thus, within the present context, the term “web pieces” refers to parts or portions which were separated there from. A web piece comprises sections, such as a first and a second end sections and a middle section positioned there between, which are topological regions, which are connected to each other and not separated or cut. The ways to achieve a separation of a web piece from a continuous web is not particularly limited. Typical ways are cutting by a sharpened blade against a counteracting anvil or another counteracting blade, though other separation techniques such as using ultrasonic or laser beam energy or water jets may be suitable, too.
It should be noted that upon separating a piece from the continuous web, the latter has a new leading end. Considering that a piece “n” is cut from a continuous web, the piece “n” had an originally leading end “L(n)”. The separation creates a new leading end of the continuous web “L(n+1)” and simultaneously a trailing end “T(n)” of the web piece “n”. The CD-folding of web piece “n” further results in that the originally leading end L(n) overlays the trailing end T(n), adjacent, but separated from the new leading end L(n+1). The physically leading edge of the web piece “n” will then be represented by the folding edge “F(n)”
Whilst the precise folding as may be executed by the method or by employing an equipment according to the present invention may be the final purpose thereof, such a system may be combined with other elements as may very advantageously cooperate therewith. In particular it allows the precise overlaying of the ends as well as all or parts of the longitudinal side margins, which may then be connected to each other very simply. To this end, and as will be discussed in more detail herein below, the folded piece can be run between a combining unit, such as a heat seal or ultrasonic bonding unit for permanently connecting the side margins, or a folding device for connecting front and rear sections by means of e.g. hook/loop type fasteners.
This and the overall principle of the present invention is further explained by referring to FIG. 1 showing the key equipment components in a schematic presentation with a schematic cross-sectional view along lines AA of FIG. 1B shown in FIG. 1A, and FIG. 2 showing the key process steps. It should be noted that these figures should not be seen to limit the invention in any way but merely serve to support the general explanation.
In FIG. 1 A, a continuous web material 100 is supplied from a web material supply unit 110 in the downstream process direction 10 towards a folding and separating unit 1000.
The web supply means can be any equipment for delivering a web. Thus it can be a roll, or a spool, a carton containing folded or “festooned” essentially endless material, optionally by including splicing equipment. Alternatively, the web material may come from another web treatment process step, or from a web forming step. Whilst the above description has explained the principle by referring to the web material being initially essentially continuous, there can be further process steps between the web supply means and the web treatment means according to the present invention. These process steps may include a separation step, such that the web materials can already be delivered as an essentially continuous sequence of web material pieces. These pieces may also be combined with other materials, which may be other web materials. Typically, these web pieces still have an extension in x- or y-direction significantly exceeding the thickness (in z-direction).
Optionally it may be supported by a first web transport means 3110.
The folding and separating unit 1000 comprises a folder web support 1100 and a web holding means 1200. As shown, the web holding means 1200 is unitary with a separating element 1300 which may interact with a counteracting separating element such as a counter blade 1350 or an anvil.
The web holding unit 1200 is adapted to temporarily hold portions of the web material (not shown in the folding and separating unit), such as by vacuum suction, by having a surface to which the web material can adhesively but releasably be connected, or may include mechanical fastening elements such as hooks from well know “hook and loop attachment” systems, if such appropriate hooks can engage with the web material. The holding unit may also comprise retractable pins that may engage with the web material in an activated state but disengage in a deactivated state.
A particular, non-limiting execution of a holding unit with small dimensions is schematically depicted in a cross-sectional view in FIG. 8. Therein, the holding unit 1200 is shown as a box 1210 with a holding surface 1230 to which the web may be attached. The holding surface 1230 may have perforations 1235 which in cooperation with a vacuum as may be supplied to the holding unit through port 1240 may temporarily hold the web (not shown) to the surface. The holding unit may optionally comprise retractable pins, in FIG. 8A shown as pins 1250 as may be activated by vacuum suction, here indicated by a flexible membrane 1260 that may bulge out upon application of the vacuum through port 1240, optionally aided by a aeration hole 1265, to the interior of the box, as indicated in FIG. 8B. The bulging of the membrane may push the pins 1250 through pin holes 1255 into the overlying web. Upon removal of the vacuum, optionally supported by filling the interior of the box with pressurized air through port 1240, the membrane will flatten and retract the pins, whilst simultaneously the lack of vacuum or the presence of pressure eases the release of the web from the web holding unit. In FIG. 8, the holding unit is shown as a unitary design with the separating means, here shown with a knife blade 1310 connected to the holding unit.
Referring to FIG. 1B, the web holding means 1200 is mounted such that it can travel around the folder web support, such as by being mounted on an arm 1280 rotating around an axis 1285 as may be positioned centred to the folder web support means, indicated by arrow 1287. As also indicated in FIG. 1A and B, the unitary web holding and separating element is shown in a first position 1205 (solid lines) downstream of the folder web support means and in a second position 1205′ (dotted lines) upstream of the folder web support means.
Further web transport means may be positioned downstream of the folding and separating unit, here shown as second web transport means 3120. Optionally, a third web transport means (here shown as 3130) may be arranged moveably relative to the unit (indicated by arrow 3133 in the dotted position in FIG. 1A).
Any of the web support or transport means can be any suitable means having an essentially endless continuous surface, which can be operated at variable and controllable surface speeds, and to which the web or pieces thereof can be temporarily affixed. If more than one web support or transport means are utilized, these can be of the same design, or can have varying design. A web support or transport means may be a belt system, comprising an endless belt, which is run at least over a first roll, which is the belt drive roll, and a second, freely running roll. In certain applications of the present invention the web support means may move at varying speed and/or may be operated e.g. in a forward—reverse direction alternating mode. Further, an equivalent embodiment to an endless belt system is a discontinuous belt system, which may be driven by one or more programmable drive means over one or more free or driven support rolls accordingly, or programmable push-pull means (such as hydraulic cylinder arrangements) to move the belt forward and backward. A web support or transport means may also be a combination of several means, such as when two belt systems are operated in a parallel position.
In FIG. 2, subsequent repeating processing steps are indicated schematically to illustrate the principle of the present invention, which is to provide improved control of the alignment of leading to trailing edges by positioning the leading edge onto the trailing edge just at the time when the latter is formed by the separation step, and in the position where the latter is formed. As described earlier, in conventional cutting/folding arrangements, such repositioning of the leading onto the trailing edge can only be done at a later stage, when both, the leading and trailing edges, have travelled a significant path length.
As shown in FIG. 2A, a continuous web 100 is running from a web supply unit over an optional first web transport means 3110 to the inlet 1400 of the folding and separating unit 1000, as may be a window or a slot as may be formed partly by a counter blade 1350 of a separating means and towards the folder web support means 1100, which may be operated at matched speed to the web supply speed. The continuous web material 100 is thus transported to the downstream end of the folder web support means. A unitary holding and separating element 1299 is travelling around the folder web support means, as indicated by arrow 1287. Thus, when the leading edge 111 of the web has just passed the downstream end of the folder web support 1100 it is transferred to the unitary holding and separating element 1299 to which it is releasably attached, such as described in the above. Upon constant web supply speed and constant speed of the folder web support means, the holding and separating element continues to travel around the folder web support, here indicated by arrow 1287, such as when it is rotating on an arm rotating around an axis 1285 positioned in the centre region of the folder web support means. At an appropriately matched speed the holding and separating means transports the end 112 with the leading edge 111 of the still continuous web 100 as attached thereto towards the upstream end of the folder web support means. As indicated in FIG. 2B, a cross-directional fold 120 is formed in the web as the originally leading end is rearwardly moved by the holding and separating unit whilst the web continues to be supplied at the web supply speed, matched by the folder web support speed. In FIG. 2C the next phase is shown, where the holding and separation unit reaches the upstream end of the folder web support means. There, the separation means 1300 of the unitary holding and separating means 1299 can separate the continuous web 100 from the now formed web piece (n) 150 now laying overfolded on the folder web support means. The original leading edge of the web now forms a first edge 151 of the web piece 150 in the first section 152 of the web piece, whilst a second edge 159 in the second section 157 of the web piece are connected through the middle section 155, which comprises the cross-directional fold 120, as further can be seen in FIG. 2F, showing an individual web piece. The positioning of the first and second sections and edges of the pieces is very accurate, as the web is fully supported during this process step.
Referring now to FIG. 7, particular effects of the present invention and benefits over prior art executions will be discussed. FIG. 7A depicts schematically a portion of the folding and separating unit, with folder web support means 1100 and a first web transport means 3100, feeding web 100 with its leading edge 111 through inlet 1400, where the separation takes place, here indicated by a combined holding and separating means 1299 and a counteracting blade 1350. A separated and folded piece of web material 150 is positioned on the folder web support means 1100, i.e. in a position shortly after the separation. However just prior to the separation the original leading end 111 of the web, (i.e. the first section 152 of the separated piece 150) is positioned onto the still uncut portion of the web, and the separation is very precisely executed in the very proximity of the original leading edge 111, thusly creating a new leading edge. Thus, there is minimal, if any possibility for the trailing edge 159 of the web piece 150 to become misaligned to the leading edge 151, as indicated by a very small distance 1030 of such uncontrolled movement. Such a longitudinal off-set between the end edges of the first and the second sections of the folded web piece may be less than 25 mm, preferably less than 5 mm, more preferably less than 2 mm, and most preferably be essentially zero. Also indicated is a further important distance for controlling the exact positioning of the end portions of a piece of folded web material to each other, namely the distance 1020 during which the web is not supported other than during the separation when travelling through the inlet towards the folder web support means. The skilled person will readily realize that small distances 1030 and 1020 will provide a better web and hence process control. Thus, the present invention can suitably be applied for a broad selection of web materials at operating speed of up to more than 100 m/min or even more than 500 m/min with very precise positioning of the overlaid sections of the material, such that the longitudinal (i.e. x-directional) offset of the two edges is less than about 5 mm, preferably less than 2 mm, but may also be essentially zero.
A skilled person will also realize that when executing the present invention the positioning of the end edges onto each other and the separation of the piece of web material from the continuous web material happen essentially concurrently, thus minimizing the time during which a leading each may move relatively uncontrolled. This time span is of course depending of the speed of web material and the movement of the holding and/or separating means. Thus, for web speed of for example 500 m/min, this time span can be significantly less than 1 sec, less than about 100 msec, or even less than 10 msec.
FIG. 7B compares now the situation for conventional cutter/folder arrangement. A first web transfer unit 7100 delivers a web 7010 towards a cutter unit 7200 with a rotating knife unit 7210 counteracting against a rotating anvil unit 7220. The cut web pieces are pulled by a .second web transfer unit 7300 and a moved to a third web transfer unit 7400. Upon actuation of a tucker unit 7500 the web piece 7150 is now cross-directionally folded and may be discharged. Here the skilled person will readily recognize that the distance 7020 over which the web is essentially unsupported when passing the cutting unit is significantly longer than in the present invention. Further, the distance 7030, over which the trailing edge of the already cut piece is moved before it gets aligned with the leading edge is significantly longer than in the present invention.
In the context of a freely moving leading edge, a further particular benefit for a very preferred execution is explained. Referring to FIG. 8, and as also indicated in FIG. 4, the box 1210 of the unitary holding and separating unit 1299 is slanted where the cutting blade 1310 is positioned, at a slanting angle γ (1330). Such an arrangement carries particular advantages, as the receding is in the direction of the movement of the freshly separated leading edge of the web just after separating. If there were no slanting (i.e. slanting angle γ being 0°), the leading edge would collide against the separating blade 1310. Thus, depending on the web speed relative to the rotating speed of the blade respectively holding and separating unit, the slanting angle may suitable be adjusted between more than 0°, but typically less than 45°
As a skilled person will readily realize, the gap between the separation counter element and the folder web support should not be excessive, depending on the stiffness of the web and/or the web supply speed. Often distances of less than about 2 cm will be suitable, though depending on web properties and possibly other supporting measures, a gap width of 5 cm or more can be tolerated.
As indicated in FIG., 2C and furthered in FIG. 2D, an optional third discharge web transport means 3300 may move towards the folder web support means to receive the folded web piece (n) and discharge it towards a second discharge web support means 3120. As shown in FIG. 1, the third web transport means is arranged retractably, such that it will not interfere with the movement of the unitary holding and separating unit.
As indicated in FIG. 2D and E, the web piece (n) 150 is moving downstream, followed by a new leading edge 111′ for the next web piece (n+1), whilst the holding and separating element 1299 continues to travel towards the downstream end of the folder web support means, where it can receive the new leading edge 111 (n+1), and the process steps can be repeated.
As shown both in FIGS. 1 and 2, the folded and separated web piece 150 may undergo further processing downstream of the folding and separating unit 1000, here indicated by a web treatment unit 4000 with a first 4010 and a second 4020 treatment roll, as may very suitably may be bonding units so as to bond longitudinally extending side margins of the web piece 150 together.
Referring to FIG. 3 now, the effect of a non-constant travel speed of the web holding means (or a unitary web holding and separating means, respectively) is explained for a the preferred execution of the web holding means rotating on a circular path, which circumscribes the folder web support.
The graph of FIG. 3 shows the instantaneous angular speed co varying versus the rotational angle α which is relative to the plane of the folder web support means. Thus, the situation as depicted in FIG. 2A corresponds to an angle alpha of 0°, in FIG. 2C of about 180°, and in FIG. 2E of close to 360°. For ease of reference, the position 1205, 1205′, . . . of the web holding means, here shown as a unitary web holding and separating means, is indicted by the schematic sketches representing the travel path thereof. The solid straight line 290 in FIG. 3 represents a constant velocity ω. Consequently, the length of the overfolded web 160 corresponds to the distance 1010 of the downstream end of the folder web support unit to the separation counter element (see FIG. 2E). The dash/dotted line 292 represents the situation, where the rotational speed ω is increased when the web end is attached thereto, i.e. for an angle α of from 180° to 360° and reduced for an angle α of from 0° to 180°. Consequently, the overfolded length 160 will be shorter than the distance d. The dashed line 294 represents the situation, where the rotational speed is decreased for an angle of from 180° to 360° and increased for an angle of from 0° to 180°. Consequently, the overfolded length will be longer than the distance d and the folding edge may project beyond the downstream end of the folder web support at the time the separation is executed (corresponding to the situation in FIG. 2C) and may already be received by a second web transport means.
Whilst the curves as indicated are shown approximately as sinusoidal curves, the shape can be different there from. The skilled person will readily realize that the area formed by the actual curves of the rotational velocity ω and the solid line 290 representing the constant rotational velocity corresponding to the web supply speed must be equal for a rotational angle ranging from 0° to 180° and for an angle from 180° to 360°.
The acceleration and deceleration of the rotation can be achieved by conventional means, such as cams or servo drives.
Whilst the foregoing describes the aspects of the principles of the present invention both with regard to the general elements of the equipment as well as the process steps as executed on the equipment, the following addresses particular executions for an apparatus set up.
FIG. 4A to F depict in a schematic presentation particular executions for a unitary separating and folding unit 1299, wherein FIG. 4A shows a top view as a partial cross-sectional view, wherein further the lines AA, BB, CC, and DD for respective side views are indicated. Referring to FIG. 4A, a folder web support means 1100 is shown as a vacuum belt system, comprising an endless belt indicated by its folder web support means surface 1110, a drive roller 1120 and idle roller 1130. The drive roller 1120 is shown to be connected via a first pulley drive system 1140 to a main shaft 1050. The main shaft 1050 is positioned between the belt surfaces of the folder web support means, here shown machine directionally and z-directionally centred between the rollers thereof. The main shaft is driven via a second pulley drive system 1055, comprising a drive belt, e.g. a V- or a tooth-belt connecting the main shaft with a main shaft drive 1057, as may be a first electric motor, optionally a servo motor. The main shaft motor speed may follow the overall machine speed, as given by the speed of the continuous web supply system. Further shown is a stator 1060, as may be connected to the overall stationary infrastructure of the apparatus, with hatched (coarse hatching from bottom right to upper left) cross-sections, comprising two main shaft bearings 1058, and 1058′, respectively.
The unit further comprises the unitary holding and separating unit 1299, the cross-section thereof being shown hatched (coarse hatching bottom left to upper right). It is supported on the main shaft by bearings 1298 and 1298′ and driven via a third pulley system 1297 by a second electric drive 1296, preferably a servo motor. The holding and separating unit projects radially outwardly with its holding and separating head at its outer end. The holding and separating head is preferably further supported by a further rotor 1295 (shown in a cross-sectional view with fine hatching bottom left to upper right) mounted via bearing 1298 on the main shaft 1050. The holding and separating head comprises holding means 1200, here shown as vacuum boreholes 1235 which are connected to a vacuum manifold 1065 as a further element of the stator 1060. The unitary holding and separating head 1299 further comprises a separating tool, here shown as a cutting blade 1310 as may be held by alignment pins 1315 and which can interact with a counter element of the separating tool, as may be an anvil or a counter blade 1350 as may be affixed to the stator.
The unit may further comprise various means such as boreholes for distributing the vacuum from the vacuum manifold of the stator to the folder web support. In FIG. 4B, a side view along line BB shows stator 1060, main shaft 1050 with main shaft pulley belt drive 1055 and main shaft drive motor 1057 as well as bearings 1058 between the stator and the main shaft. In FIG. 4C, a side view along line CC shows stator 1060, main shaft 1050 with main shaft pulley belt drive 1055 and main shaft drive motor 1057 as well as bearing 1058 between the stator and the main shaft. It further shows the third pulley belt system 1297 with second electric drive 1296 for the unitary web holding and separating unit 1299 with its bearing 1298. In FIG. 4D, a view along line DD includes the folder web support means 1100 with its surface 1110 formed by the belt and its idle (1130) and drive (1120) rollers. Further indicated is the unitary web holding and separating means 1299, showing the vacuum box 1210 and vacuum port 1240, as well as the separating means as a cutting blade 1310 in a slanted position as described in the above. The web inlet 1400 is partly delimited by the counter blade 1350, interacting with the cutting blade 1310, as also can be seen in FIG. 4E, showing a view along line EE in FIG. 4A. FIG. 4F schematically shows the same view as in FIG. 4E, however the unitary web holding and separating unit 1299 is shown at an about opposite position, ready for receiving a leading edge of a web, as may be transported via holder web support means 1100, and as may be attached to the web holding surface 1230.
FIG. 5 depicts a very similar arrangement as shown in FIG. 4A, except that the web support is executed as two parallel vacuum belt systems 1100′ and 1100″which are held in position y-directionally by shims 1150 (fine hatching bottom right to upper left. Such a design allows further elements, e.g. discharge aid means (not shown) to be positioned between the folder web supports.
In the executions as described hereinabove the web holding and web separation unit are mounted essentially unitary. This refers to a design, where both travel around the folder web support means. As it is important that the separation operation and the positioning operation of the first and second sections of the web pieces are performed within a small time window, preferably essentially simultaneously, an integral design of the separating and holding unit automatically satisfies the requirement. However, non-integral executions can be readily applied, as will now be explained by referring to an exemplary execution, which should, however not be seen limiting in any way for other non-unitary executions. FIG. 6A shows a schematic side view of a unit similar to what has been described for FIG. 1A. A web (not shown) may be fed via a first web transfer means 3100 to the inlet 1400, where a counteracting blade 1350 may be positioned. The web path continues towards the folder web support means 1100. A web holding means 1200 travels around the folder web support means 1100, here shown as a rotary movement indicated by arrow 1287. The web holding means is shown by dotted lines at a position 1205′ close to the inlet, and by solid lines (1205) at an opposed position downstream of the folder web support means, where it can receive the web end and travels with the web end attached thereto to the position 1205′ close to the inlet. The figure further indicates a second web transfer means 3120 adapted to receive the overfolded piece and a third web transfer means 3130, here shown in two laterally offset positions (solid and dotted lines) to receive the overfolded web pieces as they are still positioned on the folder web support means and transferring them to the second web transfer means 3120. The figure further indicates the position of a web treatment unit 4000 with two counteracting rolls 4010 and 4020, which may act on the overfolded web pieces, such as by connecting lateral side edges of the web piece to each other.
FIG. 6 A further depicts a separating blade 1310 not integrated with the holding means 1200, also exhibiting the slanting angle γ as discussed herein above. FIG. 6B to D show more details of the drive system for this blade (as are not included in FIG. 6A). In FIG. 6B, a view along the machine direction towards the separating unit and the inlet 1400 is schematically depicted. The knife blade 1310 of the separating means 1300 is connected by a blade arm 1320 and connecting pins 1323 and 1327 respectively to a first (1322) and a second (1326) drive wheel, which are mounted and operated synchronously such that the separating blade 1310 and its blade arm 1320 remain essentially cross-directionally oriented (i.e. do preferably not oscillate z-directionally). Whilst the mounting of a rotary blade may also be executed, the present arrangement advantageously minimizes the obstruction period during which the web material may be hindered by the separating unit to travel along its web path, thusly allowing more design freedom for the web holding means as well as for the slating angle γ. Further the web is separated essentially simultaneously across its CD-extension by interacting with the counteracting blade 1350 (here shown slightly v-shaped), thusly minimizing CD-tensions in the web. FIG. 6C depicts a schematic cross-sectional view of the knife blade and blade arm corresponding to the upper plot along lines C-C (full lines) in FIG. 6B. In FIG. 6D, the drive wheels are shown in a different position, thereby moving the knife blade and the blade arm downwardly (z-directionally) and simultaneously cross- (or y-) directionally (see the lower plot in FIG. 6B with dotted lines and primed numerals). Such a design very suitably allows that the inlet is obstructed for not more than 15 degrees, more preferably less than 5 degrees, most preferred less than 2 degrees of the angular movement of the knife blade. In addition to minimizing the obstruction time, such an arrangement of separating knife blade 1310 and counter-acting blade 1350 may very advantageously be executed as a self sharpening system. The present invention can be applied to a broad field of applications requiring accurate positioning of overfolded portions and thusly may be applied to the making of teabags, or the folding of delicate textile webs and the like. A particular application lies in the packaging field, e.g. when placing flat articles on a wrapper material and enveloping the articles by the wrapper. However a very suitable particular application is in the field of manufacturing articles to be worn on the lower torso of a wearer, such as disposable underwear or absorbent articles, such as baby or adult incontinence diapers or pants, feminine care articles and the like.
A particular suitable application relates to articles comprising longitudinally overfolded side margins, such as described in WO2011/064275, to which express referenced is made, and even more for pant style execution of such articles, i.e. where the longitudinally extending side margins of the front and rear portions of the articles are connected to each other, such that a closed pant structure is created. This can be readily executed by forming a continuous series of articles and feeding these as the continuous web to a folding and separating unit as described herein. The folded and separated pieces may be transferred to a treatment unit 4000, as e.g. depicted in FIG. 1A, where the longitudinally extending side margins or portions thereof may be connected to each other, thusly forming the closed pant structure. Instead of bonding the sections together, they may also be releasably connected to each other, such as when mechanical fasteners of the hook-and-loop type are connected to each other in the treatment unit 4000

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled) cm 11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. A method for forming a series (n, n+1, . . . ) of overfolded pieces of web material from an essentially endless web material, each piece comprising a first and a second end section and a middle section positioned there between and comprising a cross-directionally extending fold line such that said first and said second section are at least partially lying upon another,

said method comprising the steps of

a) providing an essentially continuous supply of a web material along a web path defining a downstream machine direction away from said web supply;

b) providing a folding and separating unit comprising

b1) a web inlet;

b2) a folder web support means;

h3) a web holding means;

b4) a web separating means

wherein

b5) said folder web support means is positioned downstream of said web inlet, separated by an inlet gap there from

and wherein

b6) said web holding means is moveably mounted such that it can move around said folder web support means from a position downstream of said folder web support means to a position in said inlet gap;

c) feeding a leading end of said essentially continuous web from said web supply through said web inlet over said inlet gap towards said folder web support means;

d) affixing said leading end of said essentially continuous web temporarily on said folder web support means and moving it machine directionally downstream;

e) adjusting the movement of said web holding means around said folder web support means such that said web holding means is positioned downstream of said folder web support means when said leading end of said essentially continuous web is released from said folder web support means whilst continuing to move along the machine direction downstream, such that said leading end contacts said web holding means and is temporarily affixed thereto;

f) moving said web holding means with said leading end affixed thereto towards said inlet gap, thereby forming a cross-directional overfold in said web;

g) essentially concurrently

g1) positioning said leading end over a downstream region of said web and

g2) separating a piece of web material from said essentially continuous web, and

g3) releasing said piece of web material from said web holding means,

such that

g4) a new leading end (n+1) is formed and

g5) the original leading end (n) now forms the first end section of said piece of web material overlying said second end of said web piece formed by the trailing end as being separated from said new leading end (n+1), whilst the cross-directional fold is positioned in the middle section thereof;

h) removing said web holding means from said inlet gap and allowing said new leading end (n+1) to move through said inlet gap to said folder web support means;

and repeating steps d) to h), whereby in course of step d) said overfolded piece of web material (n) is removed from said folding and separating unit.

16. A method according to claim 15, wherein said separating means is selected from the group consisting of

a knife blade counteracting with another blade;

a knife blade counteracting against an anvil;

a water jet system;

a radiation technique;

sonic cutting.

17. A method according to claims 15, wherein said web separating means and said web holding means are essentially unitary or operatively connected to each other such that both travel around said web folding means according to steps e), f) and h).

18. A method according to claims 15, wherein said separating means is a rotating knife blade counteracting with a counter-blade,

wherein said rotating knife blade is rotating around an axis essentially parallel to the machine direction of said unit;

and wherein said counter-blade is positioned in said web inlet.

19. A method according to claim 15, wherein said leading end of said web is temporarily attached to said web holding means by one or more attachment means selected from the group consisting of vacuum, mechanical engagement of the “hook-loop-type”, mechanical engagement by protruding pins.

20. A method according to claim 15, wherein said overfolding of said web is executed such that cross-directionally extending edges of the first and said second section of said piece of web material exhibit a machine-directional off-set of less than 25 mm.

21. A method according to claim 15, wherein the distance, that a trailing end edge of a second section of a piece of web material travels before it is positioned adjacent to the first section of said piece of web material is less than 25 mm along the machine direction.

22. A method according to claim 15, further comprising one or more of the following steps:

z) providing a first web transfer means and transferring said essentially continuous web to said folding and separation unit;

y) providing a second web transfer means and removing said overfolded pieces of said web material downstream of said folder web support means;

x) providing a third web transfer means and removing said overfolded pieces of said web material, whereby said third web transfer means is adapted to make a first contact to said pieces of said web material whilst these are in contact with said folder web support means;

w) providing a bonding means downstream of said holding web support means and bonding overlying portions of said piece of web material;

v) varying the speed of movement of said web holding means for adjusting the predetermined overall length of the piece of web material;

u) providing a folding means to fold pieces of a fastening means, e.g. a hook/loop type fastener which is fixed to and extending over the lateral side margins of said first or second end section of the piece of web material, around a longitudinal fold line such that it engages with the respective other end section.

23. An apparatus

for forming a series (a, n+1, . . . ) of overfolded pieces of web material from an essentially endless web material supplied by web supply means, each piece comprising a first and a second end section and a middle section positioned there between, thereby defining the longitudinal direction of said pieces, and comprising a cross-directionally extending fold line such that said first and said second section are at least partially lying upon another,

said apparatus comprising a folding and separating unit, said folding and separating unit being positioned downstream of said web supply unit and comprising

1) a web inlet for feeding an essentially continuous web material to said folding and separating unit;

2) a folder web support means positioned downstream of said web inlet, expanding along the machine direction (x-direction) and exhibiting a cross-machine extension (y-direction) aligned with the cross-direction of said piece of web material, and a height (z-directional.) extension;

3) a web holding means adapted to receive and temporarily hold a section of said web material;

4) a web separating means adapted to separate a piece of web material from said essentially continuous web material;

wherein said web holding means is moveably mounted to allow cyclic movement around said folder web support means with said web being temporarily attached thereto along a movement path forming an essentially x-z-directionally extending plane for positioning said first section of said web material piece onto said second section of said web material and for forming a cross-directional fold in said middle section of said web material or piece thereof,

wherein said web separating means is cooperatively connected to said web holding means or has its cyclic operation controlled by or is operated in registry with the cyclic movement of said web holding means.

24. An apparatus according to claim 23, wherein said web support means and web holding unit are set in motion by one or more drive systems.

25. An apparatus according to claim 24, wherein said folder web support means is operated at constant speed whilst the web holding unit travels at a cyclic speed pattern, preferably a sinusoidal pattern around said folder web support means.

26. An apparatus according to any of claims 23, wherein a gap formed between said web inlet and said folder web support is smaller than 20 cm.

27. An apparatus according to claim 23, wherein said separating means is selected from the group consisting of

a knife blade counteracting with another blade;

a knife blade counteracting against an anvil;

a water jet system;

a radiation technique;

sonic cuffing.

28. An apparatus according to claim 23, wherein said separating unit comprises a cross-directionally extending knife blade rotatably mounted to rotate around an axis of rotation which is essentially parallel to the machine direction.

29. A method according to claim 15, wherein in step b6) said movement of said web holding means is preferably rotational around an axis perpendicular to said machine direction.

30. A method according to claim 15, wherein in step e) said affixing of said leading end to said web holding means is by actuating a holding force.

31. A method according to claim 20, wherein the cross-directionally extending edges of the first and said second section of said piece of web material exhibit a machine-directional off-set of less than 2 mm.

32. A method according to claim 31 wherein the cross-directionally extending edges of the first and said second section of said piece of web material exhibit a machine-directional of which is essentially zero.

33. A method according to claim 21, wherein the distance, that a trailing end edge of a second section of a piece of web material travels before it is positioned adjacent to the first section of said piece of web material is less than 5 mm, more preferably less than 5 mm along the machine direction.

34. A method according to claim 33, wherein the distance, that a trailing end edge of a second section of a piece of web material travels before it is positioned adjacent to the first section of said piece of web material is less than 2 mm along the machine direction.

35. A method according to claim 22, wherein in step x) of providing a third web transfer means said third web transfer means is movable relative to said folder web support means.

36. A method according to claim 22, wherein in step w) of providing a bonding means selected from the group consisting of adhesive application, connecting of mechanical fastening elements of the hook and loop type, heat or fusion bonding comprising ultra sonic bonding.

37. A method according to claim 22, wherein in step w) of providing a bonding means, said bonding means is cooperatively connected with at least one of said second or third web transfer means.

38. An apparatus according to claim 23, wherein said folder web support means is a vacuum belt system.

39. An apparatus according to claim 23, wherein said web holding means is rotatably mounted.

40. An apparatus according to claim 23, wherein said movement path forming an essentially x-z-directionally extending plane, is selected from the group consisting of a circular, an elliptic and an oval path.

41. An apparatus according to claim 24, wherein said one or more drive system's is/are selected from the group consisting of drive belts, gear wheels, electrical drive motors.

42. An apparatus according to claim 26, wherein said gap formed between said web inlet and said folder web support is smaller than 10 cm.

43. An apparatus according to claim 42, wherein said gap formed between said web inlet and said folder web support is smaller than 5 cm.