Method and apparatus for making interlabial pads

The invention is directed to method and apparatus for making pads, such as interlabial pads. The apparatus includes a blending apparatus that weighs and blends fibers of different materials, at least one of which is absorbent. The blended fibers are conveyed through a chute to a fiber collection station. At the fiber collection station, collecting and feeding apparatus collects the blended fibers and feeds them to a forming apparatus that forms the blended fibers into a continuous blended-fiber web. The blended-fiber web is fed to a pad-making apparatus that cuts fluid-absorbent bodies in the blended-fiber web and laminates the bodies with at least one continuous cover web to form a laminated web. The laminated web is fed to a sealing and cutting apparatus to make the pads. Folding apparatus is provided for folding each pad along a major axis thereof.

BACKGROUND OF THE INVENTION

The invention relates generally to a method and apparatus for making pads and, more particularly, a method and apparatus for making folded feminine protection pads.

This invention is especially suited for the commercial manufacture of pads of the type shown in U.S. Pat. No. 4,595,392, entitled “Interlabial Pad”, and U.S. Pat. No. 4,673,403, entitled “Method and Pad Allowing Improved Placement of Catamenial Device”, both of which are assigned to Kimberly-Clark Corporation and incorporated by reference herein for all purposes. The pads described in these patents generally comprise a lamination of a layer of absorbent material (e.g., a blend of fibers, including cotton fibers) disposed between two cover layers, one of which is fluid pervious and faces the body when the pad is in use, and the other of which is typically fluid impervious. The pad is small compared to other feminine protection products and must be manufactured to relatively close tolerances. These size and tolerance requirements pose challenges to the efficient and economic production of this product on a commercial scale.

SUMMARY OF THE INVENTION

The apparatus and methods of the invention provide for the efficient and economic production of pads, including but not limited to relatively small pads (e.g., interlabial pads) of the type described above which require relatively tight manufacturing tolerances. Such apparatus and methods have several aspects.

In one aspect, the apparatus of the invention is an apparatus for making folded interlabial pads, each pad comprising a fluid-absorbent body laminated with at least a first cover layer of a fluid-pervious material. The apparatus includes a blending apparatus for blending fibers of different materials, at least one of which is absorbent, and for conveying the blended fibers to a fiber collection station, a collecting and feeding apparatus at the fiber collection station for collecting the blended fibers and feeding them to a forming station, and a forming apparatus at the forming station for forming said blended fibers into a continuous blended-fiber web. The apparatus further includes a pad-making apparatus for cutting fluid-absorbent bodies in the blended-fiber web, for laminating the bodies with at least one continuous cover web to form a laminated web, and for sealing and cutting the laminated web to make said interlabial pads, and a folding apparatus for folding each pad along a major axis thereof.

In another aspect, the invention is a method of making folded interlabial pads, each pad having a fluid-absorbent body laminated with a first cover layer of a fluid-pervious material. The method includes the steps of blending fibers made of different materials, wherein at least one of the fibers is absorbent, collecting the blended fibers at a collection station and feeding them to a forming station, and forming the blended fibers into a continuous blended-fiber web at the forming station. The method further includes the steps of making individual pads at a pad-making station from the continuous blended-fiber web and at least a first continuous cover web, and folding each pad along a major axis of the pad at a folding station.

Corresponding reference numbers and characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, an interlabial pad manufactured in accordance with methods and apparatus of the invention is indicated in its entirety by the reference number1. In the illustrated embodiment, the pad is generally oval in shape and has lateral projections3. The pad may be manufactured in different sizes to fit different users. For example, in one size the pad has an overall length along a major axis A1of about 3.1 in. and an overall width along a minor axis A2of about 2.7 in. In another size the pad has an overall length along a major axis A1of about 4.3 in. and an overall width along a minor axis A2of about 2.7 in. As those skilled in the art will understand, the pad may be manufactured in other sizes and shapes without departing from the scope of this invention.

In general, the pad comprises an absorbent layer or “core”5laminated between first and second outer layers7and9. The absorbent layer is preferably a blend of fibers, at least one of which is absorbent. By way of example, the fibers may comprise a blend of cotton fibers providing the requisite absorbency and rayon fibers providing resilience to the pad, with the cotton/rayon blend ratio preferably ranging from 90/10 to about 50/50, more preferably 80/20 to 55/45, and still more preferably about 60/40. Other fibers and blend ratios can also be used. Superabsorbent materials may also be included, as will be understood by those skilled in this field. The thickness of the absorbent layer will also vary, but preferably is in the range of from about 0.025 in. to about 1.5 in., and more preferably from about 0.05 in. to about 0.5 in., and even more preferably about 0.08 in. (approximately 2 mm. for low capacity interlabial pads).

The first outer layer7(sometimes referred to as the “cover” or body-side layer since it faces the body when the pad is in use) is a fluid-pervious layer which may comprise a suitable polymer, such as polypropylene BCW, having a basis weight of 22 g/m2. The second outer layer (sometimes referred to as a “baffle” layer) may comprise polyethylene film, for example, having a thickness of 0.75–1.0 mil. Pads having other laminated configurations, including those where the baffle layer is fluid-pervious, are also contemplated. In any event, the lamination is sealed around the periphery of the pad, as indicated at11.

FIGS. 3 and 4illustrate the pad in a folded condition in which the pad is folded along its major axis A1to a position in which opposite side sections1A,1B of the pad face one another, with the cover (body-side) layer7facing out for contact with the body when the pad is inserted for use. In one embodiment, the pad is maintained in this folded condition by one or more adhesive spots15on the cover (baffle) layer9. As thus folded, the lateral projections3on the pad combine to form an area which can be conveniently gripped by the user of the pad to insert it into proper position in the body.

FIG. 5illustrates various stages in an overall process for the commercial manufacture of absorbent articles of laminated construction, including the interlabial pads1described above. This process includes a fiber blending section21which blends raw fibers (e.g., cotton and rayon fibers), and a fiber collection and feed section25for collecting a supply of blended fibers and feeding them to a fiber forming section27where the fibers are formed into a relatively narrow continuous web used to make the fluid-absorbent layers of the final product (e.g., interlabial pad1). The process also includes a pad-making section31which combines the absorbent layer with the fluid-pervious (cover) layer7and, if used, the baffle layer9to make individual pads. The process also includes a folding section33which includes apparatus for folding the pads delivered from the pad-making section31, and a pad packaging section35in which the folded pads are individually wrapped and, optionally, collated into groups and placed in cartons or other suitable bulk packaging. Each of these stages of the process are described in detail below.

FIG. 6is a flow diagram illustrating one embodiment of the fiber blending section21. In this particular embodiment, the section21comprises first weighing apparatus41operable to weigh out and discharge quantities of a first fiber (e.g., cotton) and second weighing apparatus43operable to weigh out and discharge quantities of a second fiber (e.g., rayon). The weighed and discharged quantities are conveyed to a blend opener, generally designated47, where the fibers are separated (“opened”), mixed and then carried away from the blend opener by an air duct49of a pneumatic conveyor system. The pneumatic conveyor system includes an air separator51which separates the longer fibers from the air stream and delivers them to a fine opener55. The shorter fibers (“fiber fines”) are delivered to a fines collector, such as a bag filter57. The fine opener55further opens and mixes the fibers for conveyance through an air duct61to the fiber collection section25of the system. Each one of these components of the blending section is described in more detail below.

For purposes of the description, the apparatus of the invention has a machine-direction MD which extends generally in the direction of motion of the machine, a lateral cross-direction CD which extends transversely to the machine direction, and a z-direction Z. As used herein, the machine-direction MD is the direction along which a particular component or material is transported lengthwise along and through a particular, local position of the apparatus. The cross-direction CD lies generally within the plane of the material being transported through the process, and is transverse to the local machine-direction MD. The z-direction Z is aligned substantially perpendicular to both the machine-direction MD and the cross-direction CD, and extends generally along a depth-wise, thickness dimension of the material.

The first weighing apparatus41is operable to deliver successive weighed-out quantities of first fibers, such as cotton fibers. The particular unit shown inFIG. 7is a M-6 “Syncro-Feeder” weigh pan feeder sold by Fiber Controls® Corporation of Gastonia, N.C. The apparatus comprises a hopper65for holding a supply of raw fibers, and a conveyor67in the hopper for delivering clumps of fibers from the supply to a weigher housing69containing a feed conveyor71for receiving fibers from the hopper conveyor67and conveying them to an inclined lift conveyor73having pins or spikes thereon which pick fibers off the feed conveyor71and convey them to a weigher comprising a weigh hopper77at the outlet of the unit. An oscillating comb79adjacent to the upper end of the inclined conveyor73combs the fibers on the conveyor and separates (“opens”) them to prevent large clumps of fiber from entering the weigh hopper77. Fibers separated by the comb are carried to the top of the inclined conveyor73and discharged onto one or more rotating doffer bars81which effect a more uniform distribution of the fibers into the weigh hopper. Excess fibers combed out by the comb79fall back onto the feed conveyor71for recycling. The degree of fiber separation can be controlled by adjusting the speed of the inclined conveyor73and/or the spacing between the comb79and the inclined conveyor.

The weigh hopper77is equipped with a suitable device83for measuring the weight of fibers in the hopper. When a quantity of fibers having a predetermined weight is received in the hopper (e.g., 1120 grams of cotton fibers), a door85above the hopper closes to prevent further fibers from entering the weigher until after it has unloaded. When the door is closed, fibers delivered from the conveyor73accumulate temporarily in a holding chamber87above the weigh hopper77. At the appropriate time, the weigh hopper opens to deliver a quantity of fibers of predetermined weight onto a conveyor91(e.g., an endless belt conveyor) positioned below, after which the door85above the weigher opens to admit more fibers into the weigh hopper to repeat the cycle.

The second weighing apparatus43is essentially identical to the first weighing apparatus41and is operated to discharge successive weighed-out quantities of second fibers. Each of these quantities (e.g., 480 grams of rayon fibers) is combined with a weighed-out quantity of the first fibers. This may be accomplished in a variety of manners, as by dumping a quantity of second fibers directly on a pile of first fibers as the latter pile is conveyed beneath the weigher of the second unit. The combined quantities are then conveyed by the conveyor91(FIG. 6) to the blend opener.

Referring toFIG. 8, the blend opener47may be of the type sold as Model B1X24/30 Opening Blender” from Fiber Controls® Corporation of Gastonia, N.C. As shown, the machine comprises a housing97having an inlet in one side wall receiving the discharge end of the conveyor91from the weighers41,43, and an outlet in its top wall connected to the air duct49of the pneumatic conveyor system which generates a high-velocity stream of air flow through the duct in a direction away from the outlet. Mounted in the housing97immediately above the discharge end of the conveyor91is a feed roll101which is driven to match the speed of the conveyor91. The feed roll101is formed with a series of axial ridges or flutes103along its outer surface and is preferably spring biased in a downward direction against a stop (not shown) to a position in which it is spaced a predetermined distance (e.g., 3 in.) from the upper reach of the conveyor belt91. The function of the feed roll101is to spread the fibers as a layer across the width of the conveyor91, and to press the fibers down against the conveyor for a controlled feed of the fibers forward at a relatively slow speed (e.g., 9 fpm). At this point in the process, the fibers making up the layer on the conveyor91are relatively stratified, with the fiber dumped first on the conveyor (e.g., cotton) being on the bottom and the fiber dumped second being on top. The feed roll101and conveyor91are preferably driven at the same speed by a common drive the speed of which is adjustable as needed.

A large cylindric beater roll105having an axial dimension generally corresponding to the full width of the conveyor91(e.g., 24 in.) is mounted for rotation in the housing97upstream from the conveyor91and feed roll101. A multiplicity of pins or teeth107are mounted on the outer surface of the roll, each pin being threaded in a mounting block109secured to the roll. Preferably, the pins107are arranged in a number of parallel rows extending along the outer surface of the roll in an axial direction. (For example, a beater roll having a diameter of 24 in. may have 12 rows of pins mounted at equal angular intervals around the roll.) A cut-off blade111is mounted adjacent the outlet of the housing and extends the full axial length of the roll closely adjacent the tips of the pins (e.g., the clearance may be about 0.02 to 0.05 in.).

The beater roll105is rotated at relatively high speed (e.g., about 750 rpm) by a suitable motor and drive train (not shown). Fibers fed toward the roll105by the conveyor91and feed roll101are pulled and combed at high speed by the pins107and carried to the outlet of the housing97where they are drawn into the air duct49and entrained in the air stream generated by the pneumatic conveyor system. The cut-off blade111assists in the removal of fibers from the roll105. The high-speed pulling and combing action on the fibers, combined with the pneumatic conveyance of the fibers from the outlet of the machine, further separates (“open”) and mixes the fibers, as will be understood by those skilled in this field.

The air duct49conveys the fibers from the blend opener47to the air separator51by means of a high-speed air stream generated by a first transfer fan115located downstream from the separator (seeFIG. 6). In one embodiment, for example, the air moves at a velocity in the range of 2500–4000 FPM and at a flow rate of 1300–3500 CFM. As shown inFIG. 9, the air separator51in the preferred embodiment comprises a housing121having an inlet section123with an inlet125for receiving airborne fibers from the blend opener47and an outlet section127. The outlet section127has an upstream air outlet131for the exit of air from the separator and a downstream fiber outlet133for exit of fibers from the separator into the fine opener55.

The inlet and outlet sections123,127of the housing121are configured to direct the air stream entering the inlet along a path137which turns a corner, e.g., a 90° corner at the junction of the inlet and outlet sections in a preferred embodiment. As a result of this change in direction, many of the heavier fibers are moved by centrifugal force toward the outside of the turn and continue on to the fiber outlet133. A rotary air lock144at the fiber outlet133substantially inhibits the flow of air through the outlet while allowing for the passage of such fibers, thus “separating” the fibers from the air. Similar to a revolving door, the air lock144comprises a central hub145and a plurality of sealing arms147extending radially out from the hub which wipe against a wall151defining the outlet133to substantially seal against the passage of air. In the preferred embodiment, the air lock144is motor driven at a speed which may be varied to meet the fiber feed requirements of the system. As the air lock rotates, it sweeps fibers deposited between the arms147through the outlet133.

Because the flow of air through the fiber outlet133is substantially blocked by the rotary air lock144, essentially all of the air entering pneumatic distributor51exits through the air outlet131. A screen155is mounted in the housing121adjacent this air outlet131to catch the larger fibers while permitting small fibers or “fines” to pass through the air outlet to an air duct157which leads to the fines collector57, which may be of any suitable construction, such as a Model AF-2 bag filter sold by Fiber Controls® Corporation of Gastonia, N.C. The mesh size of the screen155can vary, depending on the desired characteristics of the final product, but preferably the openings in the screen have a maximum dimension of about 0.125 in. Fibers collected on the screen are removed by a rotatable blade161mounted in the housing121. The blade carries the fibers away from screen and delivers them back to the air stream for transport to the fiber outlet133.

A damper165in the air duct157connected to the fines collector57is movable between an open position, as shown, for permitting air flow through the air outlet131to the collector, and a closed position for blocking the flow of air through the air outlet. It will be noted in this regard that if the pneumatic conveyor system comprises multiple air separators and associated equipment, there may be occasions where a particular unit(s) is not needed, in which case the damper165can be closed to block the flow of air through that particular separator. The first transfer fan115is mounted in the air duct157between the air separator51and the fines collector57.

FIG. 10illustrates one embodiment of the fine opener55, which is sold as Model VFO 36 from Fiber Controls® Corporation of Gastonia, N.C. The fine opener comprises a housing171having an inlet173connected to the fiber outlet133of the air separator51, and an outlet175connected by air duct61to the fiber collection and feed section25, a second transfer fan179being mounted in this air duct61to generate an air stream for transporting fibers from the fine opener55to the fiber collection and feed section25.

A plurality of fluted nip rolls (e.g., three such rolls181,183,185are shown inFIG. 10) are mounted in the housing171immediately downstream from the inlet173and rotate to transport fibers entering the fine opener55along a path between a pair of closely spaced feed rolls187, also having fluted surfaces. (The flutes on the nip rolls181,183,185are typically relatively narrow, resembling blades or fins extending the full length of each roll at spaced circumferential intervals around the roll, while the flutes on the feed rolls187are preferably somewhat wider, resembling gear teeth with flat tops.) The feed rolls187feed the fibers to a clothing cylinder191which rotates in the housing171at high speed, e.g., 1000 rpm. Suitable card clothing193(e.g., teeth or hooks) is mounted on the clothing roll191along a continuous spiral path from one end of the cylinder to the other, as will be understood by those skilled in this art. The nip and feed rolls are preferably driven by a common DC motor197, the output of which is adjustable to vary the speed of these rolls, as needed. The clothing roll191is preferably driven by an AC motor (not shown) for rotation of the roll at a constant speed.

As the clothing roll191rotates at high speed past the feed rolls187, the clothing on the roll functions to further open the fibers and to transport them to the outlet175of the machine, where the fibers are drawn up and through the outlet. A cut-off blade201mounted adjacent the outlet has an edge positioned closely adjacent the roll191for substantially preventing fibers from being carried by the clothing roll past the outlet175. A similar blade205is mounted with its tip end adjacent the upper feed roll187for preventing build-up of fibers on the feed roll. Air flows into the housing171through an air inlet207.

A fiber-level sensor (e.g., photocell), not shown, is mounted in the housing171of the fine opener55for controlling the level of fiber delivered to the inlet173. In the event the fibers back up to a level considered excessive, the sensor is operable to signal the upstream weighing apparatus41,43and blend opener47to stop further delivery of fibers until the level of fibers drops below a predetermined level (e.g. the level of the sensor), after which the upstream equipment is signaled to resume operation. Other sensing devices operating in different manners may be used.

FIGS. 11 and 12illustrate apparatus at the fiber collection and feed section25of the system downstream from the fine opener55. This apparatus comprises, in one embodiment, a feed chute, generally designated221. The feed chute collects (accumulates) a supply of blended fibers and feeds the fibers as an initial layer or mat of blended fibers to the fiber forming section27. More specifically, the feed chute221comprises a housing223having an inlet225connected to the air duct61for receiving fibers from the fine opener55, and an outlet227through which a continuous supply of blended fibers is discharged to the forming section. The particular feed chute221shown in this embodiment is a Model FCF-40 chute feeder sold by Platt-Saco-Lowell, formerly of Greenville, S.C.

The housing has an upper section229which includes an upper chute231for holding a supply of fibers delivered through the inlet225, and a lower section233. One wall237of the upper chute231is perforated (e.g., the wall may be a screen of fine mesh) to permit the escape of incoming air from the chute. The level of fiber in the upper chute231is controlled by suitable means, such as a pressure switch241adjacent the inlet operable to signal a shutoff of the upstream equipment (e.g., weighing apparatus41,43, blend opener47and fine opener55) in the event the air pressure in the upper housing section229exceeds a predetermined pressure, indicating that the upper chute231is full, and to signal activation of the upstream equipment when the pressure falls below a predetermined pressure, indicating that the supply of fiber in the upper chute has fallen to a level requiring replenishment.

A feed roll245is rotatably mounted in the lower section233of the housing immediately below the upper chute231to feed fibers from the upper chute231to a beater roll247. The fiber is fed past the feed roll245through a gap251(FIG. 12) defined by a guide surface255spaced from the feed roll245a suitable distance (e.g., about 0.25 in.). The feed roll245is preferably equipped with card clothing (not shown) similar to the clothing cylinder of the fine opener55, and the beater roll247has a construction similar to the beater roll105in the blend opener47, although it is preferably somewhat smaller (e.g., a diameter of 10.5 in. with twelve rows of pins or teeth). The feed roll245is preferably rotated by a variable speed motor (not shown) to feed the fiber to the beater roll247at the desired rate. The beater roll247is preferably rotated at a suitable speed (e.g., 1800 rpm) by a constant speed motor to feed the blended fibers into the lower section233of the feed chute and to perform an additional opening step on the fibers. Fibers on the beater roll247are directed by an adjacent guide wall261in the housing to the upper end of a fiber accumulation chute263in the lower section233of the housing223.

Referring toFIG. 11, the lower accumulation chute263is defined, in a preferred embodiment, by vertical walls, one of which comprises a shaker plate267pivoted at its upper end for back-and-forth oscillation by means of a shaker arm assembly generally designated271adjacent the lower end of the plate. The shaker arm assembly271comprises one or more shaker arms273each of which has an inner end connected to a wheel275at an off-center location, and an outer end connected (as by a clevis277) to the shaker plate267, the arrangement being such that rotation of the wheel causes the shaker arm and the shaker plate to oscillate back and forth. This movement prevents the bridging of fibers in the lower chute263and facilitates the uniform feed and packing of fiber in the chute to provide a supply of blended fibers, e.g., a column of substantially uniform density or “basis weight” (typically measured in grams/square meter). The length of the shaker arm273is adjustable by means of a turnbuckle281or the like, so that the amplitude of the oscillating movement can be varied, as needed. The shaker arm wheel275(or wheels) is preferably driven at the desired speed by a variable speed DC motor (not shown). Other means may be used instead of the shaker plate and shaker arm assembly271for facilitating the flow and packing of fibers in the lower chute263.

The level of fibers in the lower accumulation chute263is controlled by suitable means, such as a pair of upper and lower sensors, e.g., upper and lower photo cells indicated at285and287, respectively, inFIG. 11. The upper photo cell285is operable to signal a shutoff of the upstream equipment (e.g., weigh apparatus41,43, blend opener47and fine opener55) in the event the height of the column of fibers in the lower chute263exceeds a predetermined height, indicating that the lower chute is full. The lower photo cell287is operable to signal activation of the upstream equipment when the height of the column falls below a predetermined level, indicating that the need for additional fibers. The upper and lower sensors285,287are preferably closely spaced for maintaining the height of the fiber column relatively constant so that the density of fibers discharged from the chute is substantially uniform.

Fibers in the lower chute263are fed through the outlet227by feed means comprising, in one embodiment, a pair of compression rolls291defining a compression nip293immediately adjacent the outlet of the housing. These compression rolls291preferably function to compress the fibers into a continuous mat or layer295of blended fibers which is discharged through the outlet227for delivery to the fiber forming section27of the system.

FIGS. 13–15illustrate one embodiment of the forming section27of the system of the invention. In this section, the layer295of fiber delivered from the outlet227of the feed chute221is broken up and reformed as a preferably (but not necessarily) narrower layer having a width generally corresponding to the width of the absorbent layer of the final product (e.g., layer5of pad1). In general, the fiber forming section27of this particular embodiment comprises a transfer device301for feeding the layer of fiber from the outlet227of the feed chute to a fiberizing station303at the downstream end of the transfer device. In the preferred embodiment, the transfer device is a slide (also designated301) down which the layer gravitates. Alternatively, the transfer device could be an endless conveyor or other device.

Apparatus generally designated311is provided at the fiberizing station303for breaking up the incoming layer295into individual fibers, a process which may be referred to as “fiberizing”. As illustrated, this fiberizing apparatus311comprises a feed mechanism including a feed roll315spaced from a guide surface317(FIG. 14) to form a gap319through which the layer295of fibers is fed to a fiberizing mechanism comprising, in one embodiment, a roll321having teeth, e.g., a lickerin roll, mounted immediately adjacent the gap. Alternatively, a rotary hammer mill or other device may be used.

The feed roll315is carried by a pair of levers325(only one shown inFIG. 14), each of which has a pivot connection327with the machine frame for adjusting the size of the gap319. Preferably, the gap is set to be less than the thickness of the incoming layer295(e.g., 0.012 in. compared to about 2.5 in.) so that the layer of fibers is compressed and fed forward to the fiberizing roll321at a controlled rate of speed (e.g., 6 fpm). The feed roll315is preferably driven by a variable speed DC motor329(FIG. 13). The fiberizing roll321preferably rotates in a direction opposite the rotational direction of the feed roll315, and the teeth on the roll321function to break up or “fiberize” the layer295into small tufts and individual fibers. The fiberizing roll is preferably driven by an AC motor333at a constant, relatively high speed (e.g., 1800 to 2400 rpm).

The fiber forming section27also includes a conveyor335(FIG. 15) having foraminous forming surface337positioned below the fiberizing roll321and preferably running in a direction generally transverse (e.g., at right angles) to the direction of feed to the fiberizing roll, and fiber-directing apparatus, generally designated341, for directing fibers from the fiberizing roll to the surface337on which they are reconstituted as a “reformed” layer343(FIG. 14) on the conveyor335, hereinafter referred to as the “reforming” conveyor. In one embodiment, the forming surface337of the reforming conveyor335comprises an endless belt made of wire mesh or screen, the openings being appropriately sized for the forming (e.g., 11% open area). The forming surface337is preferably substantially narrower than the width of the layer295fed to the fiberizing roll321(e.g., 3 in. versus 40 in.) and, in one embodiment, extends generally parallel to the axis of rotation of the fiberizing roll.

It will be understood that a fiberizing mechanism other than a roll with teeth (e.g., lickerin roll321) could be used without departing from the scope of this invention. Any mechanism (e.g., a rotary hammer mill) can be used, provided it is capable of breaking up the layer295into separate fibers for reformation on the reforming conveyor337in substantially random orientation.

Referring toFIGS. 14 and 15, the fiber-directing apparatus341comprises, in the preferred embodiment, an air chamber347positioned between the fiberizing roll321and the reforming conveyor335. The air chamber347has an upper inlet end located adjacent the fiberizing roll321and a lower outlet end located immediately above the forming surface337of the conveyor335, although the air chamber could have orientations other than vertical without departing from the scope of this invention.

As viewed inFIG. 15in which the reforming conveyor335transports fibers from right to left, the upper end of the air chamber has a length generally corresponding to the axial length of the fiberizing roll321which, in turn, is preferably at least as wide as the layer295delivered from the feed chute221. Referring toFIG. 14, the air chamber347has a front (left) wall defined at least in part in one embodiment by a door351pivoted at its upper end at353so that the door may be swung up and down between open and closed positions, a rear wall355, and opposite side walls357(FIG. 15). The air chamber347has a width (i.e., the distance between the front and back walls351,355of the chamber) at its lower end generally corresponding to the width of the reformed layer343of fibers formed on the reforming conveyor335. The forming surface337of the conveyor335is positioned over an elongate air manifold361which communicates with a vacuum fan (not shown) by means of air duct363. The arrangement is such that operation of the fan generates an air stream down through the air chamber347and through the forming surface337to “air lay” a layer of fibers on the forming surface. Air is provided to the air chamber347via an airway367(FIG. 14) adjacent the juncture of the fiberizing roll321and the upper inlet end of the air chamber.

The airway has a throat371which is adjustable in size to regulate the flow of air to the air chamber, adjustment being effected by means such as a movable sabre bar373or other suitable device. Seals are provided to prevent the drawing of air into the air chamber347, including sealing strips375along the sides of the door, the top edge of the door, and strips along the bottom edges of the door and rear wall (FIG. 14). The vacuum fan should be sized to generate a relatively high-speed stream of air through the air chamber347sufficient to direct fibers from the fiberizing roll321onto the reforming conveyor335to form a layer of blended fiber of suitable thickness and density.

The reformed layer343may be formed on a conveyor other than an endless belt. For example, the reformed layer could be deposited or “air laid” on a rotatable vacuum drum of the type well known in the art for producing air formed fibrous webs.

The breaking up or disintegration of the layer295of fibers by the fiberizing roll321and deposit of the fibers as a reformed layer343on the reforming conveyor335tends to randomize the orientation of the fibers, resulting in good tensional strength of the final product in all directions and more uniform wicking and distribution of bodily fluid in all directions away from the location of impingement on the fibers. Further, reforming the layer295at an angle (e.g., 90°) which is transverse to the machine direction MD of feed to the fiberizer321tends to average any cross sectional variations in the layer.

As best illustrated inFIG. 15, the reforming conveyor335is driven by a drive roll381powered by a suitable motor to drive the conveyor at a speed substantially faster than the speed at which the initial layer295of fiber is delivered from the feed chute221to the fiberizing roll321. Preferably, the width of the initial layer295delivered from the feed chute is at least 5 times greater than the width of the reformed layer343on the reforming conveyor335, and the reforming conveyor preferably runs at a speed at least 10 times greater than the speed at which the initial layer is fed to the fiberizing roll.

By way of example, the initial layer may have a width of about 40 in. and a thickness of about 2.5–3.0 in., and the speed at which the initial layer is fed to the fiberizing roll may be 5–8 fpm. On the other hand, the reformed layer may have a width of about 3 in. and a height of about 0.5 in., and the reforming conveyor335may run at a speed of 370 fpm. The speed of the reforming conveyor is preferably adjustable. Fiber dust is removed from the reforming conveyor by a cleaner385mounted at a location upstream from a belt drive roll. In one embodiment, the cleaner comprises an air jet which is operable to blow fibers off the conveyor and a vacuum pick-up (not shown) opposite the air jet. Other cleaning mechanisms may be used. The endless belt of the conveyor335is maintained under tension by a conventional tensioning device indicated at389.

The door351at the front of the air chamber347may be opened to access the reforming conveyor537and associated equipment. During normal operation, however, the door351is held in its closed position by a pair of locking pins393. An additional security system, generally designated395inFIG. 14, may also be provided to lock the door closed.

After the fibers are reformed on the reforming conveyor335as a preferably narrower layer, the reformed layer343is compressed to a final thickness. Preferably, compression occurs in two stages. In a first stage, the reformed layer is lightly compressed by a compression conveyor401positioned above the reforming conveyor335downstream from the air chamber347(FIGS. 15–17). The compression conveyor401is preferably an endless belt having a lower reach spaced from the forming surface337of the reforming conveyor335by a distance sufficient to lightly compress the incoming layer343of fibers. The vertical position of the compression conveyor401is preferably adjustable to vary the size of the gap between the two belts and thus the magnitude of the compressive forces applied to the layer, as needed.

In the second stage, the layer343is more severely compressed by a de-bulking module, generally designated405inFIG. 17. In one embodiment, this module405comprises a pair of pressure rolls having hardened surfaces, the lower pressure roll407being mounted in fixed position and the upper roll409being vertically movable relative to the lower roll, as permitted by a power cylinder411mounted above the upper roll. The power cylinder exerts a downward force (e.g., 2400 lbs) on bearing blocks415at the ends of the upper roll to hold the blocks down against fixed stops (not shown) which maintain a gap of predetermined size between the pressure rolls unless the compressive force exerted by the rolls407,409on the layer343exceeds a predetermined force, in which event the upper roll409will yield in an upward direction. The size of the gap at the nip of the rolls407,409can be adjusted by changing the position of the fixed stops. The compressive force exerted by the pressure rolls is preferably sufficient to compress the layer343to a final thickness (e.g., 0.08 in. for an interlabial pad) which is substantially the same as the thickness of the absorbent layer of the final product (e.g., layer5of pad1). As thus compressed, the layer343is conveyed, preferably as a continuous integral web417(FIG. 17) of blended fibers, by one or more conveyors421to the pad-making section31.

Referring toFIGS. 16–19, the pad-making section31comprises, in general, first and second unwind rolls425,427on which are wound webs7W,9W of material corresponding to the cover and baffle layers7,9of the final pad1, and a first cutting station431at which the web417of blended fibers is cut to form individual absorbent bodies in the web (e.g., cores5for pads1). Section31also includes a web sealing station435at which the cover and baffle webs7W,9W are applied to opposite faces of the bodies5to form a laminated web437(FIG. 19) which is sealed around the bodies5, and a second cutting station441at which the laminated web437is cut around the pads prior to transport of the pads to the folding section31. Each of these components is described in detail below.

A conveyor (e.g., an endless belt conveyor447including a belt tensioning device449) receives the blended-fiber web417at the entry end of the pad-making section, which is the left end as viewed inFIG. 18, and conveys the web417to the first cutting station431. Cutting apparatus is provided at this station comprising, in one embodiment, opposing cutting rolls451,453which define a first cutting nip CN1. One of these rolls (451) is a knife (die) roll and the other (453) is an anvil roll. In this embodiment, the knife roll451is mounted in fixed vertical position below the anvil roll453but this orientation may be reversed. The knife roll451has a series of cutting dies (blades)457(FIG. 20) mounted on the roll in a pattern corresponding to the pattern of absorbent bodies (e.g., cores5) to be cut in the web. The anvil roll453has a hardened, polished metal surface and is preferably positioned so that the gap between the rolls at the first cutting nip CN1is sufficiently small (e.g., 0.0005 in.) to enable the cutting blades457to cut substantially completely through the blended-fiber web417.

The anvil roll453is preferably vertically movable relative to the knife roll451in the same manner as described above in regard to the upper pressure roll409, a power cylinder461being provided for this purpose. The cylinder exerts a downward force on bearing blocks of the anvil roll453to hold the blocks down against fixed stops (not shown) and thus maintain the size of the gap (if any) at the first cutting nip CN1unless the compressive force exerted by the rolls451,453on the web417exceeds a predetermined force, in which event the upper roll will yield in an upward direction. The size of the gap can be adjusted by changing the position of the fixed stops, as will be understood by those skilled in this field.

After the web417has been cut to form the absorbent bodies (e.g., cores5), it is desirable to maintain the bodies in precise position as they are transported through the pad-making section31, so that the various components of the final pads (e.g., pads1) are in substantially precise registration. To this end, the knife roll451is a vacuum roll comprising a cylindric body465(seeFIGS. 20–22) formed with vacuum passages including, in one embodiment, axial passages467running from the ends of the body along the length of the body and radial passages469extending from the axial passages467radially outward to form vacuum openings471(FIG. 20) in the outer surface of the body. Vacuum boxes475are mounted at opposite ends of the body465, each box being open adjacent a respective end face of the body. The vacuum boxes475communicate by means of air ducts479with a vacuum system comprising at least one vacuum fan (not shown) for generating a negative pressure in the vacuum boxes to draw air through the passages467,469in the body. Seals483around the opening in each vacuum box475are positioned close to the respective end faces of the rotating cylindric body465to seal against leakage of air from the box.

In the embodiment shown inFIGS. 18 and 20, the vacuum boxes475extend over about a 90° arcuate segment along the upper part of the knife roll451from about the 12:00 position adjacent the first cutting nip CN1to about a 3:00 position for transfer of the absorbent bodies to a first transfer cylinder485, the transfer occurring at a first transfer nip TN1defined by the knife roll451and transfer cylinder485. The vacuum openings471in the outer surface of the knife roll451are so arranged and located that the absorbent bodies cut from the web are vacuum gripped and held in precise position on the knife roll as it rotates in a clockwise direction from the cutting nip CN1to the first transfer nip TN1, where the absorbent bodies are transferred to the first transfer cylinder485rotating in the same direction, as will be described. Scrap material491(i.e., trim from the web417around the absorbent bodies) is removed from the knife roll during or after the transfer of the absorbent bodies takes place, as by means of a vacuum duct493(seeFIG. 22). The duct493has an inlet adjacent the knife roll451and communicates with the aforementioned vacuum system to draw the scrap material491into the duct for delivery to the inlet section of the feed chute221for recycling, or to a suitable waste collector for disposal.

Referring toFIGS. 20 and 21, the body465of the knife roll451may be of multi-piece construction, comprising a shaft497surrounded by a sleeve499fabricated as a plurality of arcuate segments (e.g., 3 such segments499A–C are illustrated inFIG. 20) affixed to the shaft by suitable fasteners501(FIG. 21) which extend through bores503in the sleeve499and are threaded into the shaft497. In one embodiment, each segment499A–C carries two cutting dies or blades457, each having an outline corresponding to the shape of the absorbent body5to be cut from the web. An insert507(FIG. 23) of a compressible but resilient material is secured to the outer surface of the body465of the knife roll451inside the perimeter of the blade457, as by a suitable adhesive. The insert507may be an adhesive-backed body of cross-linked polyethylene foam, for example, having a tensile strength of 44 to 55 psi and a compression such that the material deflects 25% at a pressure of 12.7 to 15.5 psi. Such a foam is commercially available under the trademark “Volara” from McMaster-Carr Supply Company of Chicago, Ill. In its relaxed (uncompressed) condition or state, as shown inFIG. 23, the insert507projects out from the surface of the knife roll451, preferably a distance slightly less than the height of the cutting blade457. For example, for a cutting blade457having an overall height of 0.19 in., the insert507may project out a distance of 0.125 in. The insert507is porous (due either to the porous nature of the insert material or to holes509made in the insert) to provide for the transfer of vacuum from the vacuum openings471in the surface of the knife roll451through the insert. When the web417of absorbent material passes through the cutting nip CN1, the insert507is compressed to permit cutting of the material by the blade457. After the web passes through the cutting nip, the tendency of the insert507to expand to its relaxed state exerts a small outward pushing force on the absorbent body5cut by the cutting blade457. This outward force assists in the clean separation of the absorbent body5from the web417and the transfer of the absorbent body to the first transfer cylinder485at the first transfer nip TN1.

As shown inFIGS. 24 and 25, the first transfer cylinder485comprises a hollow body in the form of a drum515having a cylindric outer surface formed with a pattern of vacuum holes519generally corresponding to the shapes of absorbent bodies5transferred from the knife roll451. A vacuum box521mounted in fixed position inside the drum515has an arcuate surface525defining a vacuum opening527positioned closely adjacent the inside wall529of the drum. The vacuum box519communicates by means of one or more air ducts531with the aforementioned vacuum system so that a negative pressure is generated in the vacuum box to draw air through the vacuum holes519in the outer surface of the drum as the drum rotates past the box. Seals533around the opening527in the vacuum box wipe against the inside wall529of the rotating drum515to seal against leakage of air. In the embodiment shown inFIG. 18, the vacuum box extends over more than about a 180° (e.g., about 190°) arcuate segment along the lower half of the drum from about the 9:00 position adjacent the first transfer nip TN1to about a 3:00 position for transfer of the absorbent bodies5to the web sealing station435, as will be described. The vacuum holes519in the first transfer cylinder485are located and arranged such that absorbent bodies5transferred to the first transfer cylinder485at the first transfer nip TN1are vacuum gripped and held in precise position on the transfer cylinder as it rotates in a counterclockwise direction from the nip TN1to about the 3:00 position. An exemplary pattern of vacuum holes519is illustrated inFIG. 24.

In the embodiment shown inFIG. 18, the web sealing station435includes sealing apparatus comprising, in one embodiment, a pair of opposing sealing rolls541,543defining a sealing nip SN, one such roll (541) being shown as a lower sealing roll and the other as an upper roll. The upper sealing roll543has a smooth, uninterrupted cylindric surface and is mounted in the same manner as the anvil roll453at the first cutting section431, a power cylinder547being provided for this purpose. The lower sealing roll541is mounted for rotation in a fixed vertical position and defines a second transfer nip TN2with the first transfer cylinder485. The lower sealing roll541has a construction similar the knife roll451, except that the body of the roll has a smooth cylindric outer surface551(FIGS. 26 and 27) formed with a pattern of recesses or pockets553therein which are sized and shaped for receiving the absorbent bodies5transferred from the first transfer cylinder485. Each pocket553has an outline which is slightly oversize relative to the outline of an absorbent body5. The pocket553has a depth (i.e., in the Z direction) slightly greater than the depth of the absorbent body5so that the absorbent body is not compressed at the sealing nip SN. Alternatively, the depth of the pocket553can be made less than the thickness of the absorbent body5to provide for some compression of the absorbent body at the sealing nip, if desired.

The depth of the pocket553can be controlled by placing one or more perforated inserts of predetermined thickness in the pocket. Like the knife roll451at the first cutting station431, the lower sealing roll541is also formed (e.g., machined) to have a series of axial and radial vacuum passages557,559therein to create vacuum openings561in the outer surface551of the roll. Also like the knife roll451, vacuum boxes565are mounted adjacent opposite ends of the lower sealing roll541and are connected by air ducts567to the vacuum system for generating a vacuum at the vacuum openings561on the roll541.FIG. 26illustrates a pair of exemplary pockets553formed in the outer surface551of the lower sealing roll541.

In the embodiment shown inFIG. 18, the vacuum boxes565at the ends of the lower sealing roll541extend over more than about a 180° (e.g., about 190°) arcuate segment along the upper half of the roll from about the 9:00 position adjacent the second transfer nip TN2to about a 3:00 position for transfer of the absorbent bodies5and accompanying webs7W,9W to a downstream second transfer cylinder571defining a third transfer nip TN3with the lower sealing roll541. In an alternate embodiment, the vacuum boxes565at the ends of the lower sealing roll541extend over an arcuate segment along the upper portion of the roll from about the 9:00 position adjacent the second transfer nip TN2to about a 12:00 position for transfer of the absorbent bodies5and accompanying webs. As will be more fully described below, the two sealing rolls541,543function to apply the cover and baffle webs7W,9W from the unwind rolls425,427to the absorbent bodies5to form the laminated web437, and then to seal the laminated web for delivery to the third transfer nip TN3.

Apparatus for feeding the cover web7W for lamination with the absorbent bodies is shown inFIG. 18. This apparatus comprises the unwind supply roll425of cover web7W material, corresponding to the cover layer7of a final pad (e.g., pad1), mounted on a shaft575driven by a variable speed motor (not shown). The speed of the motor is controlled so that the rate at which web7W is fed from roll425closely matches the rate at which the blended-fiber web417is fed to the pad-making section31. One aspect of this feed control involves a sensing device581downstream from the unwind roll425for sensing a change in web tension due, for example, to the decrease in roll diameter as web is fed from the roll, and for signaling the motor to speed up or slow down to maintain a substantially uniform tension in the web corresponding to the desired speed. In one embodiment, the sensing device581comprises a dancer bar583pivoted on the frame of the machine, a dancer roll585rotatable on the bar and in contact with the web7W, and a potentiometer (not shown) for sensing movement of the bar as a result of changes in web tension. Other sensing devices can be used. The cover web7W is directed by a series of idler rolls589to the lower sealing roll541where it is pulled through the second transfer nip TN2.

As the web is pulled through the nip, absorbent bodies5are transferred from the first transfer cylinder485to the lower sealing roll541in a position overlying the cover web7W to laminate the absorbent bodies on the web and thus form a lamination. The cover web7W is of an air and fluid-pervious material, so that both the web and the absorbent bodies are subject to the vacuum force applied by the vacuum openings561in the sealing roll541to hold the web and bodies in precise position on the lower sealing roll (seeFIG. 19). Further, the pockets553in the outer surface551of the lower sealing roll541are positioned for receiving the absorbent bodies as they are transferred from the first transfer cylinder485, the end result being that the cover web and absorbent bodies are held by the vacuum of the lower sealing roll in the pockets and held in this laminated condition for conveyance to the sealing nip SN.

Apparatus for feeding a baffle web9W for lamination with the cover web7W and absorbent bodies5is also shown inFIG. 18. This apparatus comprises the second unwind supply roll427of baffle web material9W, corresponding to the baffle layer9of a final pad (assuming a baffle layer is included), mounted on a shaft591driven by a variable speed motor (not shown). The operation and control of this motor is similar to that of the first unwind roll425described above and will not be repeated. A web tension sensing device595similar to device581is provided downstream from the second unwind roll427. A series of idler rolls599direct the baffle web9W past an applicator601which functions, in one embodiment, to apply (e.g., spray) a suitable adhesive (e.g., hot-melt adhesive) to a face of the web9W to be applied to the absorbent bodies5and at locations generally corresponding to the peripheral seal11of the final pad, as shown, for example, inFIG. 1. Other types of applicators, adhesives and/or sealing methods may be suitable. Additional idler rolls downstream from the applicator601direct the baffle web9W to the sealing nip SN defined by the sealing rolls541,543, where the baffle web is applied over the face of each absorbent body5opposite the cover web7W, with the adhesive on the baffle web facing the lower sealing roll.

As the lamination of webs7W,9W and absorbent bodies5pass through the sealing nip SN (FIG. 19), pressure is applied by the sealing rolls541,543to bring the adhesive on the baffle web9W into pressure contact with opposing surfaces of the cover web7W to seal the cover and baffle webs together around each absorbent body5. If a hot-melt adhesive system is used, the distance between the applicator601and the sealing nip SN should be such that, given the speed at which the baffle web9W is fed forward, the adhesive is sufficiently heated at the sealing nip to form a proper seal. Alternatively, one or both of the sealing rolls541,543may be heated (ultrasonically or otherwise) to form heat seals around the absorbent bodies.

In the preferred embodiment ofFIGS. 19,26and27, the vacuum openings561in the lower seal roll541vacuum grip the sealed laminated web537. As the sealing roll rotates, it exerts a pulling force on the web and conveys the web in a clockwise direction from the sealing nip SN to about a 3:00 position where the web is transferred to the second transfer cylinder571at the third transfer nip TN3. In one embodiment, the construction of the second transfer cylinder571is essentially identical to the construction of the first transfer cylinder485. In the embodiment shown inFIG. 18, the vacuum box603inside the second transfer cylinder571extends over more than about a 180° (e.g., about 190°) arcuate segment along the lower half of the cylinder from about the 9:00 position adjacent the third transfer nip TN3to about a 3:00 position for transfer of the sealed laminated web537to the second cutting station441. The vacuum openings (not shown) in the second transfer cylinder571are located and arranged such that the web is vacuum gripped and pulled as the cylinder rotates in a counterclockwise direction, while maintaining the web in precise position. In an alternate embodiment, the second transfer cylinder571does not have a vacuum box or vacuum openings and the web is transferred to the second transfer cylinder571without using vacuum openings.

The second cutting station441includes second cutting apparatus comprising, in one embodiment, a second pair of opposing cutting rolls607,609defining a second cutting nip CN2where the sealed laminated web537is cut to form individual pads (e.g., pads1). In this particular embodiment, the cutting rolls comprise a lower knife roll607and an upper anvil roll609similar to the two cutting rolls451,453at the first cutting station431. Preferably, the knife roll607at the second cutting station is a vacuum roll having a construction and operation similar to the first knife roll451at the first cutting station, except that as shown inFIG. 18, the vacuum boxes611at the ends of the roll607extend over more than about a 180° arcuate segment along the upper part of the knife roll from about the 9:00 position adjacent a fourth transfer nip TN4between the knife roll607and the second transfer cylinder571to about a 3:00 position for transfer of the cut web to a third transfer cylinder615at a fifth transfer nip TN5between the knife roll607and the cylinder615. Alternately, the vacuum boxes611at the ends of the roll607extend over an arcuate segment along the upper part of the knife roll from about the 12:00 position adjacent the second cutting nip CN2to about a 3:00 position for transfer of the cut web to the third transfer cylinder615.

As shown inFIG. 28, the vacuum openings617in the outer surface of the knife roll607at the second cutting station are arranged and located such that the laminated web537is vacuum gripped and held in precise position on the knife roll as the roll rotates in a clockwise direction to pull and convey the web from the fourth transfer nip TN4to the second cutting nip CN2. The knife roll607carries cutter blades (or dies)621as shown inFIG. 28, for example, spaced at repeating intervals around the roll. The cutting blades621are configured so that, as the laminated web537travels through the second cutting nip CN2, the cover and baffle webs7W,9W are cut around the absorbent bodies5to form individual pads (e.g., interlabial pads1). Because the cover and baffle webs are typically of a polymer material, the cutting blades621preferably have an interference fit with the anvil roll609(i.e., no gap or clearance) at the second cutting nip CN2to ensure that the laminated web is cut completely through. (If different web materials are used, the clearance at CN2may vary.) The cutting action forms individual pads1surrounded by remaining scrap portions625of the web, sometimes referred to as trim and typically having a ladder-like appearance. As shown inFIG. 28, the rails of the “ladder”, indicated at627, correspond to the unused extreme side edge margins of the web537and the rungs of the “ladder”, indicated at629, correspond to unused portions of the sealed areas of the laminated web. If required or desired, resilient inserts similar to the inserts507previously described may be placed inside the cutting blades621. After cutting at the nip CN2, the pads1and trim625are vacuum conveyed by the knife roll607from the second cutting nip CN2to the fifth transfer nip TN5for transfer to the third transfer cylinder615.

The third transfer cylinder615is essentially identical to the first and second transfer cylinders485,571except that the vacuum box635(FIG. 29) inside the third transfer cylinder extends only along an arcuate segment of about 90° on the bottom part of the roll from about the 9:00 position at the fifth transfer nip TN5to about the 6:00 position where the roll forms a sixth transfer nip TN6with a vacuum conveyor641which conveys the pads to the folding section of the machine. Vacuum openings (not shown) in the outer cylindric surface of the third transfer cylinder615are located and arranged for vacuum gripping the pads1transferred from the knife roll607and holding them in predetermined positions relative to one another as the transfer cylinder615rotates in a counterclockwise direction to the sixth transfer TN6nip. The gap between the third transfer cylinder615and the vacuum conveyor641at the nip TN6should be no greater than (and preferably slightly less than) the thickness of the pads1to insure a clean separation of the pads from the trim625created at the second cutting nip CN2. The continuous strip of trim material625is removed preferably downstream from the sixth transfer nip TN6and fed along a path (e.g., at645inFIG. 29) to an appropriate waste collector. The pads1are deposited on the conveyor641in an unfolded condition in which each pad lies flat on the conveyor in a pre-folding position in which the baffle web9W faces up, the cover web7W faces down, the major axis A1of the pad extends generally parallel to the direction of feed, and the pad is generally centered on the conveyor641in a transverse CD direction with respect to the conveyor.

To maintain the various cutting rolls, sealing rolls, and transfer cylinders in timed relationship with one another, they are preferably driven by a common drive mechanism. This mechanism includes a drive motor and a drive train connecting the motor to the various rolls and cylinders. The drive train may comprise a series of timing belts and pulleys, for example, or a series of gears or other drive elements, as will be understood by those skilled in this field.

In the embodiment shown in the drawings, the axial length of each of the cutting rolls, sealing rolls and transfer cylinders is sufficient to accommodate only one lane of the absorbent bodies and pads. However, it will be understood that for higher throughput, additional lanes can be established by using wider rolls and cylinders, with accompanying modifications to associated equipment.

The vacuum conveyor641for conveying pads1to the folding section33comprises, in one embodiment (FIG. 30), three endless vacuum belts, namely, a center belt643and a pair of side belts645trained around rollers647to have generally horizontal, generally parallel, generally co-planar upper reaches spaced from one another to define first and second slots S1, S2. (FIGS. 30 and 32) The belts are perforated and relatively narrow, the overall width of the conveyor being not substantially greater than the width of an unfolded pad1carried by the conveyor so that the side belts645support respective side sections1A,1B of the pad and the center belt643supports the center section of the pad. The belts are preferably driven by a common drive651(FIG. 30). A vacuum box653having vacuum openings655in its upper surface is mounted immediately below the upper reaches of the conveyor belts643,645and communicates with a vacuum system by means of an air duct (not shown), the arrangement being such that a vacuum is generated at the perforations in the center and side belts to hold each pad in the stated pre-folded position for delivery to the folding station33. Other means may be used for conveying the pads from the pad-making section31to the folding section33.

Pads delivered to the folding station by the conveyor are folded by folding apparatus, generally designated661. In one embodiment (FIGS. 31 and 32), this apparatus includes a hold-down member comprising a rotatable disc663mounted for rotation about a generally horizontal axis spaced above the vacuum conveyor641to define a gap665between the peripheral edge of the disk and the upper reach of the center belt643. The hold-down disk663preferably rotates in the same direction as the conveyance of the pads and at about the same speed, and it contacts each pad to hold it down against the center belt643as the pad is conveyed through the gap665and folded.

The folding apparatus661further comprises a plurality of folders comprising, in one embodiment, two folding disks671mounted on opposite sides of the hold-down disc for rotation about a horizontal axis spaced below the upper reaches of the belts643,645. As shown inFIG. 31, each folding disk671is formed with ramps675at spaced intervals around its peripheral edge. The ramps675on the two disks671are adapted to project up through respective slots S1, S2between the belts643,645and to contact the side sections of the pads1A,1B being conveyed as they pass below the hold-down disk663. The folding discs671preferably rotate in the same direction as the hold-down disc663so that a respective pair of ramps675on the two folding disks contact each pad as it passes through the gap and fold the side sections1A,1B up to a position in which they face one another, as shown inFIGS. 4 and 32.

Optionally, adhesive may be applied to each pad1at an appropriate location on the pad (e.g., spot679inFIGS. 1 and 3) before it is folded. One embodiment of this option is shown inFIGS. 30 and 33as comprising a glue dispenser681having a nozzle683for dispensing a metered amount of adhesive (e.g., in bead form) onto an applicator687positioned immediately above the conveyor641. In the illustrated embodiment, the applicator687is generally rectangular in shape and, in the orientation shown, has relatively narrow upper and lower edges691for receiving adhesive from the nozzle683of the dispenser681.

The applicator687is rotatable by a driven shaft693to rotate in timed relation to the movement of the pads1on the conveyor641to apply a small area of adhesive to the upper surface of each pad at an appropriate location as the pad passes beneath the lower edge691of the applicator carrying the adhesive (seeFIG. 33). Preferably, the speed of the applicator687at its upper and lower edges691generally corresponds with the speed of conveyor641. The dispenser681can operate intermittently in timed relation to the driven shaft693to deliver discrete quantities of adhesive to the upper edge691of the applicator687as the lower edge is applying glue to a pad below, or the dispenser can operate continuously to deliver a continuous bead of adhesive from the nozzle683that is picked up by the upper edge of the applicator as it moves through the bead.

Alternately, the glue dispenser681is positioned such that the nozzle683for dispensing a metered amount of adhesive is located adjacent (e.g., about a distance less than the diameter of a bead of adhesive) to the pad1. The dispenser681is intermittently actuated to apply adhesive directly to the product. Preferably, a vacuum force holds the pad to a consistent thickness as it passes the nozzle683on the conveyor641. In one embodiment, a glue dispenser commercially available from Nordson Corporation of Westlake, Ohio is used. It will also be understood that adhesive may be applied by applicators which have other shapes and/or which operate in different ways. Operation of the dispenser and applicator is controlled by a sensor (e.g., a photocell697) upstream from the dispenser681for sensing the presence (or lack of presence) of pads.

To accommodate the application of adhesive to the pads1, the hold-down disk663has a series of openings (e.g., notches701) extending inward from its outer edge at spaced intervals around the disc. The notches701are sized and located to permit the side sections1A,1B of each pad to contact one another at the location of the adhesive spot679during the folding process. The adhesive assists in maintaining each pad in its folded condition prior to wrapping of the pad and after the pad is removed from its wrapper for use.

After the pads1are folded, they are conveyed by a suitable conveyor mechanism, generally designated705, in their folded condition to the packaging section35of the machine. In one embodiment (FIG. 34), the conveyor mechanism705comprises a pair of endless transport belts709,711having spaced apart reaches defining a gap713for receiving pads1delivered from the vacuum conveyor641at the folding station33. The gap713is sized such that the transport belts apply a compressive force to the pads sufficient to grip and carry them to the packaging section35. In one embodiment, the belts709,711are twisted 90 degrees so that they receive the folded pads1in a generally vertical orientation and then rotate the pads 90 degrees for delivery to the packaging section35in a generally horizontal orientation.

The two transport belts709,711have upstream ends trained around a pair of spaced apart generally vertical rollers717(FIG. 34) rotatably mounted on a generally horizontal support plate719carried by a bracket721with horizontal slots723affixed to the frame of the machine, and downstream ends trained around a pair of generally horizontal rollers727rotatably mounted on shafts729journalled for rotation in bearing housings731mounted on two brackets733with slots735affixed to the frame. Preferably, the shafts723carry sprockets connected to a suitable variable speed motor (not shown) by a timing belt for rotation of the shafts by the motor. The slots723,735in the various brackets721,733allow the positions of the belts709,711to be adjusted in vertical and horizontal directions, as needed.

The vertical rollers717at the upstream ends of the belts709,711are secured by threaded fasteners741received in transversely extending slots743in the support plate719, the fasteners being movable in the slots to allow the spacing between the two belts to be adjusted. A pair of belt guide assemblies, each generally designated747, maintain the upstream ends of the belts709,711in proper position on their respective vertical rollers717. In the embodiment shown inFIG. 34, each assembly747comprises a guide roller751adapted for contact with a respective belt709,711, and a linkage mounting the guide roller751on the support plate719.

In the illustrated embodiment, this linkage comprises an L-shaped angle bar755affixed to the underside of the support plate719by a threaded fastener (not shown) received in a slot757in a horizontal leg of the angle bar, an upper tubular arm761having a pivot connection763with a vertical leg of the angle bar, a lower arm765having a telescoping fit with respect to the upper arm761, a locking collar767for securing the upper and lower arms in fixed longitudinal and rotational positions relative to one another, and a lever781having a pivot connection783at its lower end with the lower arm765and a pivot connection785at its upper end with a roller support787on which the guide roller751is rotatably mounted. This linkage enables the position of the guide roller751to be adjusted in at least three different dimensions, i.e., in a first dimension corresponding to the machine direction MD by using the slot757in the angle bar755to vary the position of the bar relative to the plate719; in a second dimension corresponding to the Z direction by pivoting the upper and lower arms761,765about pivot connection763to raise and lower the guide roller751; and in a third dimension by rotating the lower arm765on its longitudinal axis relative to the upper arm761to swing the guide roller751to an angled position in which its axis of rotation is angled relative to a vertical plane.

By using one or more of these adjustments, the guide roller751can be positioned to contact its respective belt709,711at any orientation necessary to prevent the belt from “walking” up or down on its respective vertical roller717and thus maintain the belt substantially centered on the roller. The spacing between the belts at their downstream ends can be varied by using the slots735in brackets733to adjust the position of the horizontal rollers727. The downstream ends of the transport belts are positioned immediately adjacent the packaging section35for delivery of the pads to wrapping apparatus, generally designated801.

Referring toFIGS. 29 and 35, the wrapping apparatus801includes a forming device, generally designated805, for receiving pads delivered by the transport belts709,711, and web-pulling means generally designated807downstream from the forming device805for pulling a continuous web811of flexible wrapping material (e.g., polyethylene or other suitable material) from a supply roll813of such material past the forming device to wrap the pads1in a tube815of the material which, when later sealed and cut, will form wrappers for the pads. The supply roll of packaging material is supported by a shaft821driven by a variable speed motor (not shown) to control the speed at which the web is fed from the roll. The speed of the motor is controlled by a web-tension sensing device827similar to the sensing devices described earlier for the unwind rolls425,427. In the event the sensing device senses a change in web tension, it signals the motor to rotate the shaft821either slower or faster to maintain the speed at which the web811is pulled from the roll813substantially constant.

Referring toFIGS. 36–40, the forming device805comprises first and second web folding members831,833having angled folding edges831A,833A adapted for contact by respective opposite side margins M1, M2of the web811as the web is pulled past the folding edges (seeFIG. 36), a web guide837for guiding the web toward the folding edges, and an opening839between the web guide and the folding edges adapted to be spanned by a central portion of the web as the web is pulled past the forming device. In one embodiment, the folding members comprise upper and lower folding plates or boards (also designated831,833) having opposing surfaces defining a relatively narrow gap843(FIG. 40) extending in the machine direction MD as the web is pulled over the forming device805. The folding members831,833also have spaced apart side walls847which flare down and out from their respective folding plates. The folding edges831A,833A at the upstream ends of the plates831,833are angled in opposite directions relative to the direction of web travel and at a suitable angle relative to the direction of web travel, preferably in the range of from about 14° to about 20° and more preferably from about 16° to about 18°. The folding members may have configurations other than as described above.

The web guide837comprises, in the embodiment shown inFIG. 37, a generally triangular web contact surface or wall851having a base edge853and opposite side edges855which taper up to an apex857. The wall851is inclined relative to the plane of the opening839and is positioned for contact by the web811of packaging material pulled from the supply roll813. A tongue861extends from the apex857toward the opening839. The tongue861is preferably either generally coplanar with the lower folding plate833or spaced below the folding plate a vertical distance less than the thickness of the pad. The web guide also has side walls865extending in a downstream direction from respective folding edges855to integral junctures with respective side walls847of the folding members. For economy, the web guide and folding members are preferably formed as a single piece of bent sheet metal (e.g., 14 gauge 304 stainless steel sheet) although they may be constructed as separate parts.

As shown inFIGS. 36 and 38, the tapered folding edges855of the web guide837serve to initiate the folding of the web811and to guide it across the opening839toward the folding boards831,833for contact by the angled folding edges831A,833A. A pair of notches869extend down from the apex857of the wall851of the web guide on opposite sides of the tongue861. Being under tension, the web811deforms down into these notches869as the web is pulled past the forming device805.

The wrapping apparatus801also preferably includes what may be referred to as a force-applying device which, in the preferred embodiment, comprises a relatively short narrow endless belt875extending over the forming device805generally along the central portion of the web811. (The purpose of this belt will be described later.) The belt875is supported by a pair of rollers877,879, one or both of which are driven to move the belt875at the same speed as the web811moves past the forming device805. In the embodiment shown inFIG. 41, the upstream roller877is mounted on a driven shaft881rotatable in a bearing housing883secured by a bracket885with slots887to the frame of the machine. The downstream roller879is rotatable in a bearing housing891carried by a support plate893. A power actuator (e.g., power cylinder895) is connected to the support plate873for pivoting the support plate and the downstream roller877relative to the bearing housing883to vary the position of the belt875as needed for maintenance and for adjustment relative to the forming device805.

Referring toFIG. 38, the upstream end of the endless belt875is positioned above the web guide837to define a gap901for receiving pads from the transport conveyor705. Pads fed one at a time into the gap901are carried by the moving web811and the belt875in the machine direction MD across the opening839and past the folding boards831,833. In the embodiment shown in the drawings, the upstream roller877of the belt875is disposed over the apex857and tongue861of the web guide837, and the downstream roller879positioned generally over the opening839. The lower reach of the belt875is inclined downward in the machine direction MD and forms an inclined surface which is positioned for contact by the pads. Thus, as each pad1moves past the tongue861and over the opening839, it is forced down against the web and moved to a level where it will pass below the lower folding plate833.

This downward force causes the web in the area of the opening839to “cup” so that a pocket or depression905is formed in the web for cradling the pads (seeFIG. 39). The cupping action is preferably accompanied by a resilient deformation or stretching of the web any, in a preferred embodiment, by a resilient compression of the pad, e.g., to a point where the pad has a compressed thickness in the range of 50–100% of the uncompressed thickness of the pad and more preferably about 95% or greater. As a result, the web811is tightly wrapped around the pads as the web is pulled past the folding edges831A,833A of the folding plates831,833to form the aforementioned tube815around the pads. In addition to applying a downward force in Z direction, the friction between the belt875and the pads1subjects the pads to a pushing force in the machine direction MD to assist in the movement of the pads toward the folding boards.

FIGS. 38A–38Cillustrate an alternate force-applying device, generally designated918, for applying a downward force on the pads. The device is positioned above the web guide837and comprises a hold down plate920having downwardly extending side flanges921which define a channel922for receiving pads from the transport conveyor705. Pads fed one at a time into the channel922are carried by the moving web811in the machine direction MD across the opening839and past the folding boards831,833. In the embodiment shown in the drawings, the hold down plate920has a lower surface which is inclined downward in the machine direction MD and is positioned for contact by the pads. Thus, as each pad1moves past the tongue861and over the opening839, it contacts the lower surface of the hold down plate920and is forced down against the web811and moved to a level where it will pass below the lower folding plate833as explained above.

As illustrated inFIG. 38A, the hold down plate920is carried at the lower end of a rigid arm having an upper end pivoted at924to the frame of the machine for movement between a lowered position as shown inFIG. 38Ain which the hold down plate is properly positioned with respect to the web guide837, and a raised position (not shown), the two ranges of pivotal movement being established by two stops936,938. A torsion spring928urges the arm toward its lowered position. In one embodiment, a proximity switch (not shown) is mounted adjacent the arm923. A backed-up or jammed condition of pads1in the channel922causes an upward force on the hold down plate920and a corresponding movement of the arm923against the bias of the spring928. This movement triggers the proximity switch, alerting operators of the jammed condition or stops the movement of transport conveyor705.

Preferably, as shown inFIGS. 38B and 38C, the device918also includes a plenum member (e.g., plate930) which overlies the hold down plate920and defines a plenum chamber above the plate, and an air fitting929on the plenum member930for supply of pressurized air from a suitable source to the plenum chamber. The hold down plate920is perforated with air holes934through which air is directed to form an air film between the hold down plate920and the pads1as they pass beneath the plate. The air film reduces friction between the pads and the hold down plate920as the pads move toward the folding boards831,833. Additionally, it will be understood that other devices may be used for applying the stated pressing force on the pads.

The web guide837, opening839and folding members831,833shown in the drawings can assume other shapes without departing from the scope of this invention. For example, the length and shape of the tongue861can vary. Further, the size of the opening839can vary, although it is preferred that the opening have a width W in the cross direction CD (transverse to the direction of web travel) about 97% of the width of each of the pads, and a length L in the machine direction MD of about 18% of the length of each pad.

The position of the forming device805is preferably adjustable in the machine direction MD, cross direction CD, and Z direction. While this adjustment can be achieved in various ways, one such way is illustrated inFIG. 35. In this particular embodiment, the forming device805is mounted on a post909affixed at its lower end to a channel911extending in the machine direction MD. The channel, in turn, is attached to a cross rail915which is supported by a mounting plate917with slots919fastened to the frame of the machine. The channel and rail911,915are provided with fastener openings to permit adjustment of the forming device in the MD and CD directions, and the slots919provide for adjustment of the device in the Z direction. Thus, the position of the forming device can be adjusted in the MD, CD and Z directions, as needed.

Referring toFIG. 38, an adhesive applicator, generally designated925, is provided at the forming device805for applying a suitable adhesive to at least one margin M1, M2of the web811before or as it is folded to secure the tube815around the pads1after exit from the forming device805. In one embodiment, the applicator925comprises a gun927capable of dispensing a suitable adhesive (e.g., a hot-melt glue) through a nozzle931positioned close to the web811(e.g., within 0.003 to 0.004 in.) for the transfer of adhesive to margin M1of web as the web moves past the nozzle931and before the margin is overlapped with the opposite margin M2of the web. Preferably, the nozzle transfers a continuous bead or stripe of adhesive to the web, as indicated at933inFIGS. 36 and 40, but it will be understood that the adhesive may be intermittently applied in the web, if desired. The adhesive dispensed from the nozzle931is preferably in extruded bead form, but it may also be sprayed. In one embodiment, an air supply line932provides a pressure source to open the gun927and an air supply line934provides a pressure source to close the gun927.

In the embodiment shown inFIGS. 42–44, the applicator further comprises a housing935connected to an adhesive supply line937for the delivery of adhesive to the gun and, optionally, to a pressure air line939(e.g., 20 psi air) for the delivery of air under pressure for dispensing of the adhesive through the nozzle931. The position of the nozzle is adjustable in the Z direction to vary the spacing between the nozzle and the web, as needed.

FIGS. 42–44illustrate one possible way to achieve this adjustment. In this particular embodiment, the housing935of the applicator is attached by means of a bracket945with slots947to a crosshead949bridging the piston rods953of a power actuator957. The actuator, in turn, is mounted on a tongue961slidable in a vertical groove963in a mounting block965attached to an L-shaped bracket967affixed to the frame. A screw shaft971(FIG. 44) rotatable in the mounting block965extends through a threaded bore971in the tongue961, the arrangement being such that rotation of the screw draft971by a handwheel975causes the tongue and actuator957to move in a vertical direction. Thus, the position of the adhesive applicator925in the Z direction can be roughly adjusted by extension and retraction of the piston rod953, and more finely adjusted by rotation of the handwheel975.

When the spacing between the nozzle931and the web811is set, a thumbscrew979threaded through a bar981affixed to the bracket967is tightened against the handwheel975to lock the screw shaft971against rotation until a further adjustment is needed. The bracket967holding the mounting block965has horizontal slots985(FIG. 42) to enable the position of the nozzle931to be varied in the CD direction extending transversely of the web. Adjustment in the MD direction is effected by means of slots947. Other mechanisms can be used to provide for adjustment of the position of the applicator925relative to the web811.

Alternatively, the adhesive gun927can be positioned for dispensing adhesive for application to the opposite margin M2of the web after it has been folded over to a position overlying the pads but before margin M1has been folded face-to-face with M2. A notch (not shown) may be provided in the lower folding board833for this purpose. A portion of this notch extends upstream from the angled folding edge831A of the upper folding board831, leaving the folded-over margin M2of the web exposed for application of an adhesive from the gun927. After the adhesive is applied, the upper folding board831folds the other margin M1of the web over the underlying margin M2as the web is pulled past the folding boards.

The web-pulling means807for pulling the web811past the forming device805comprises, in one embodiment (FIGS. 35 and 45), a vacuum conveyor, generally designated1001, in the form of an endless perforated belt1003(the perforations being omitted inFIG. 45for simplicity) trained around upstream and downstream rollers1007,1009, at least one of which (e.g., roller1007) is rotated by a drive shaft1011mounted in a bearing housing1013secured to a bracket1015on the frame. A vacuum box or manifold1019is supported on the frame below the upper reach of the belt1003and has openings1021in its upper surface for drawing a vacuum through the belt to grip the tubular wrapper815formed by the forming device805, thus providing the force necessary for pulling the web811in the machine direction MD over the forming device and for feeding the tubular wrapper containing the pads to a wrapper sealing station1025downstream from the forming device805.

The conveyor1001also includes an upper endless compression belt1027supported by upstream and downstream rollers1029and1033, respectively. As shown inFIG. 45, the upstream roller1029is driven by a shaft1035rotatable in a bearing housing1039affixed to a bracket1041fastened to the frame of the machine. The downstream roller1033is supported by a shaft1041journalled in a bearing plate1045having a pivot connection1047with the bearing housing1039. The bearing plate1045is pivotable about the connection by means of a power actuator (e.g., cylinder1051) to move the compression belt1027between a lowered position in which the lower reach of the belt is substantially parallel or having a small decline with respect to the upper reach of the lower belt1003, as shown inFIG. 35, and a raised position as shown inFIG. 45. When in its lowered position, the compression belt1027applies a compressive force to the tubular wrapper815to press the overlapping margins M1, M2of the wrapper together to form a good adhesive seal along the tube, and also to assist in the feed of the wrapper in the machine direction MD. The compression belt1027can be raised when not in use, as for maintenance.

Sealing apparatus, generally designated1100inFIG. 35, is provided at the sealing station1025for sealing the tubular wrapper815between the pads1in seal areas1103extending transversely with respect to the tube815in the CD direction (seeFIG. 46). Referring now toFIGS. 35 and 47, the sealing apparatus1100comprises upper and lower sealing rolls indicated at1107and1109, respectively, each of which carries a plurality of sealing jaws1113extending axially along the circumference of the roll at spaced intervals around the roll (e.g., six sealing jaws at 60° intervals around the roll). Each jaw1113comprises a base1117fastened to the roll in conventional fashion, as by threaded fasteners1119, and a sealing bar1121projecting out from the base having a heated sealing area1125.

A heating element (not shown) is embedded in the bar for heating the sealing area1125of the bar to a temperature sufficient to soften the wrapper material. The rolls1107,1109are driven by suitable drive mechanisms1131to rotate in timed and synchronized relation to one another so that the heated sealing jaws1113on the two rolls sequentially move into registration with one another and simultaneously contact opposing (e.g., upper and lower) surfaces of the tubular wrapper815at intervals spaced along the web to press the surfaces together and form the seal area1103between the pads, as will be understood by those skilled in this field. The operation of the heating elements is controlled by temperature sensors embedded in the sealing bars1121adjacent the heating elements. Preferably, the sealing areas1125of the sealing bars1121are textured (e.g., roughened) to mechanically deform the opposing surfaces of the tubular wrapper815and thus establish a mechanical bond between the surfaces to hold them together prior to complete cooling of the seal. A supporting surface1131is provided immediately upstream of the sealing rolls1107,1109for supporting the tubular wrapper as it enters the nip of the rolls.

The tubular wrapper815is pulled between the two sealing rolls1107,1109by suitable means, such as a pair of upper and lower endless belts1135,1137similar to the endless belts1003,1027previously described immediately upstream from the sealing station1025. These belts1135,1137may also function to feed the sealed wrapper815to a cutting station1041where cutting apparatus1043is provided for cutting the sealed tubular wrapper at the seal areas1103to form individual wrapped pads.

Referring toFIG. 29, the cutting apparatus1043comprises, in one embodiment, a pair of upper and lower cutting rolls designated1051and1053, respectively. The construction of these rolls is similar to that of the sealing rolls1107,1109, except that the sealing jaws on one roll are replaced by cutting blades and the sealing jaws on the other roll are replaced by anvil bars which support the web for cutting by the blades, in a conventional manner. Rotation of the cutting rolls1051,1053is timed and synchronized to cut through the tubular wrapper815at the seal area1103. As shown schematically inFIG. 46, the cut1061across each seal area is generally at the middle of the seal (in the machine direction MD) so that one cut simultaneously forms the trailing seal of one wrapper and the leading seal of the following wrapper. The individually wrapped pads are then discharged into a suitable receptacle1065(FIG. 16) or onto a conveyor for transport to an optional collating station where the pads may be grouped by hand or by a suitable collating mechanism for further packaging in cartons or the like.

The operation of the apparatus described above to carry out the methods of the invention will now be described. Raw fibers (e.g., cotton and rayon) are weighed out and mixed in the desired proportion in the fiber blending section21of the system. This process is initiated by loading fibers of one material (e.g., cotton) on the in-feed conveyor67of the first weighing apparatus41(seeFIG. 7) for delivery to its respective weigher77, and by loading fibers of another material (e.g., rayon) on the in-feed conveyor of the second weighing apparatus43for delivery to its respective weigher. The weighers77are operable to weigh out quantities of these fibers in correct proportion by weight (e.g., 1120 grams of cotton and 480 grams of rayon) and to unload them onto the conveyor91for delivery to the blend opener47.

In one embodiment, the unloading is timed so that the downstream weigher77unloads its weighed-out batch of fibers directly on top of the batch unloaded by the upstream weigher77, so that a single pile of fibers containing the correct proportions of fibers is delivered to the blend opener47(seeFIG. 8). Fibers fed into the blend opener are opened and mixed, to some extent, and then transported through air duct49to the air separator51(FIG. 9). There, the air and fiber fines are separated from the longer fibers and delivered to the fines collector57. The longer fibers are conveyed to the rotary air lock144which rotates at the necessary speed to feed the longer fibers to the inlet of the fine opener55at the desired rate. The fine opener55(FIG. 10) further separates and mixes the fibers and delivers them to the feed chute221via the air duct61.

The fibers entering the inlet section229of the feed chute221(FIG. 11) are entrained in a stream of air and directed into the upper chute231where they collect above the feed and beater rolls245,247. Air entering the upper chute231exits through the porous wall237of the chute. The feed and beater rolls245,247rotate to perform a separation and blending operation on the fibers before they are delivered to the accumulation chute263in a substantially separated (“opened”) and mixed condition, with the fibers of one type being blended with the fibers of the other type. The feed of the fibers down in the accumulation chute263is assisted by the oscillation of the shaker plate267. Further, the frequency and amplitude of the oscillation can be varied to control the density of the fibers delivered to the compression rolls291adjacent the outlet227of the feed chute.

As the fibers pass between these two rolls291, they are formed into a layer295of desired thickness for deposit on the transfer device301leading to the forming section27of the machine (FIG. 13). The thickness of the layer295and the speed at which it is delivered is controlled by the size of the gap293between the compression rolls291and the speed of the rolls, respectively. For example, the layer295may have a thickness of about 2 in. and the rolls may have a surface speed of about 6 fpm. The density of the layer295(e.g., weight per unit length) is controlled at least in part by the height of the column of fibers in the accumulation chute263, the amplitude and frequency of the oscillation of the shaker plate267, the compressive force applied by the compression rolls291, and the speed of the rolls291. Preferably, the density of the fibers discharged from the feed chute221is in the range of 0.005–0.16 g/cc, more preferably in the range of 0.010–0.030 g/cc, and even more preferably in the range of 0.013–0.019 g/cc. The layer295of blended fibers delivered from the feed chute221may be relatively wide, e.g., 40 in. wide, although this dimension may vary considerably. If sufficiently compacted, the layer295may be in the form of an integral web capable of independently maintaining its body and shape. However, the layer may also be a thickness of loosely compacted (or non-compacted) fibers combining to form a body the shape of which is not self-sustaining.

The layer295of fibers from the feed chute221gravitates down the slide301(or is conveyed in some other manner, as by an endless conveyor) for delivery to the gap319between the feed roll315and the adjacent guide surface317, as shown inFIG. 14. The rotating feed roll315serves to feed the layer295of blended fibers to the fiberizing roll (e.g., lickerin roll321) which breaks up the fibers. After this fiberizing operation, the fibers fall and are swept into the inlet of the air chamber347where they are air laid onto the forming surface337of the conveyor335and reformed into a layer343having a width generally corresponding to the final width of the absorbent body in the pad (e.g., body5in pad1). As noted previously, the fibers making up this reformed layer343are randomly oriented and blended into a substantially homogenous mixture having strength in MD and CD directions, and further having the ability to effectively absorb and distribute fluid deposited on the material. The thickness of the reformed layer343is controlled by the speed of the reforming conveyor335, which is variable, and by the amount of fibers delivered into the air chamber347for deposit on the foraminous forming surface337of the conveyor.

As thus reformed, the layer343is transported to the compression belt401where the fibers are lightly compressed, and then to the compression rolls407,409where the fibers are more severely compressed into the aforementioned continuous web417of absorbent material having a thickness generally corresponding to the thickness of the absorbent body (e.g., body5) in the final product (FIG. 17). The compression belt401may be eliminated, if not needed. The thickness of the web417is controlled primarily by the spacing between the two compression rolls407,409. Following compression, the web is conveyed to the pad-making section31of the system.

At the pad-making section (FIG. 18), the web417is fed in the machine direction MD between the two cutting rolls451,453at the first cutting station431, where the web is cut to form individual absorbent bodies5, an exemplary shape of which is illustrated inFIG. 20. The web is then vacuum conveyed by the knife roll451to the first transfer nip TN1where the absorbent bodies are transferred to the first transfer cylinder485, while maintaining the bodies in precise position relative to one another. The trim (waste material)491from the cutting operation is preferably removed after the transfer by means of the vacuum duct493for delivery of the trim to a suitable collector, not shown. Meanwhile, the absorbent bodies5are vacuum conveyed by the first transfer cylinder485to the second transfer nip TN2.

The cover web7W is also fed from the unwind roll425to the second transfer nip TN2, where bodies5are successively transferred from the first transfer cylinder485to positions on the cover web overlying respective pockets553in the sealing roll541. The bodies5and underlying web7W are drawn by the vacuum openings561into the pockets553and held in place as they are conveyed to the sealing nip SN. If a baffle web9W is used, it is combined with the cover web7W and absorbent bodies5at the sealing nip SN, as described previously (FIG. 19), and the sealed laminated web437is then vacuum conveyed to the third transfer nip TN3where it is transferred to the second transfer cylinder571. The second transfer cylinder571vacuum grips the laminated web and conveys it to the fourth transfer nip TN4where the web437is transferred to the lower cutting roll607for vacuum conveyance of the web to the second cutting nip CN2at the second cutting station441. There, the two cutting rolls607,609cut the laminated web437around the absorbent bodies5to form individual pads (e.g., pads1) which are held by the vacuum openings617in the lower roll607as the web is conveyed to the fifth transfer nip TN5. The pads1are transferred at TN5to the third transfer cylinder615, which conveys the pads and deposits them on the 3-belt vacuum conveyor641in an orientation where the pads preferably lie flat on the conveyor with the baffle layer9of the pad facing up (if a baffle layer is used), with the central section of the pad supported by the center belt643, and with the side sections1A,1B of the pad supported by the side belts645. The trim or waste portion of the web (indicated at625inFIG. 28) is removed by allowing the trim to follow around the third transfer cylinder615for delivery to a suitable collector, or by pulling it straight down from the fifth transfer nip TN5for disposal.

The vacuum conveyor641conveys the pads1to the folding section33while maintaining the pads in fixed positions relative to one another. At the folding section (FIG. 30) the side sections1A,1B of each pad are folded up by the two folding disks671while the center section of the pad is held down by the hold-down disk663. As thus folded, the pad appears as shown inFIG. 3, with the pad preferably lying in a generally upright (e.g., vertical) orientation. Prior to folding, an adhesive such as a hot-melt glue may be applied to the upper surface of the pad (e.g., the baffle layer9) by the applicator687, so that when the two side sections1A,1B are folded face to face, the adhesive will secure the pad in its folded condition. After each pad1is folded, and while it is still being held upright by the folding disks663, it is fed into the gap713between the transport belts709,711for conveyance to the packaging section35(FIG. 34). The 90° twist in the belts709,711functions to rotate the pads1to a generally horizontal orientation for delivery to the forming device805. The position of the guide rolls751can be adjusted, if necessary, to maintain the twist belts properly centered on the vertical rollers717at the upstream ends of the belts.

At the packaging section35, the web811of flexible wrapping material is pulled over the forming device805by the web-pulling means807, with the web first advancing over the web guide837and then past the folding boards831,833(seeFIGS. 36 and 38). As the web811is pulled over the forming device, pads1are fed from the transport belts709,711, one at a time, into the gap901between the tongue861of the web guide and the overhead belt875, the latter moving at the same speed as the web. As each pad enters this gap, it is conveyed with the web in the machine direction MD over the opening839between the tongue861and the folding boards831,833. As the pad moves over the opening839, the downwardly inclined lower reach of the belt875applies a force on the pad1to press it into the central portion of the web811, causing the web to cup and, preferably, to stretch somewhat in the cross direction CD, as best illustrated inFIG. 39. This cupping of the web creates a volume in the web, i.e., a depression or groove or pouch905, to begin the formation of the tubular wrapper815around the pad. The force applied to the pad1is sufficient to cause the web811and underlying central portion of the web to move down to a position where the top of the pad will clear the lower folding board833. This position can be adjusted by operation of the power cylinder895to pivot the belt879up or down relative to the folding device805. As noted previously, other force-applying devices (e.g., an inclined stationary surface) can be used to initiate the formation of the tubular wrapper815around the pads.

As the pad1and central portion of the web811move below the lower folding board833, the side margins M1, M2of the web engage respective folding edges831A,833A of the folding boards and are folded into face to face relation, as shown inFIG. 40, to form the tubular wrapper815around the pad. In the embodiment shown inFIG. 40, the side margins M1, M2of the web are folded so that the facing surfaces of the margins are constituted by opposite faces of the web811to form a so-called overlap seam on the tube815. However, it will be understood that the side margins M1, M2could be folded to make a fin seam where the facing surfaces of the margins are constituted by the same face of the web811. In either event, adhesive933is applied to at least one of the side margins M1, M2by the applicator925before the margins are folded into face to face relation, the adhesive being on the surface of the side margin which will eventually face the opposing side margin after the folding operation is complete. The spacing between the nozzle931of the applicator925and the surface of the web811to which the adhesive is applied is preferably such that the web draws a continuous bead of uniform volume (or a series of intermittent spots of uniform volume) from the nozzle as the web passes the nozzle. Alternatively, the adhesive may be sprayed or otherwise applied to the web811.

The tubular wrapper815containing the pads1is pulled in the machine direction MD by the vacuum belt1003(FIG. 45), which in the preferred embodiment provides the primary force for pulling the web811over the forming device805. As the newly-formed tubular wrapper815passes between the vacuum belt1003and the overhead compression belt1027, it is subjected to a compressive force to adhere the side margins M1, M2of the web together to form a longitudinal seam extending the length of the tubular wrapper before the tube is fed between the two sealing rolls1107,1109at the sealing station1025. As the two sealing rolls rotate, the sealing bars1121on the upper roll1107move into sequential registration with the sealing bars1121on the lower roll1109to seal the tube in the seal areas1103between the pads (seeFIG. 46). The tubular wrapper tube containing the pads is pulled through the sealing station1025by the vacuum belt1137and compression belt1135downstream from the sealing station. These belts also serve to feed the sealed tube to the cutting station1041where the cutting rolls1051,1053cut across the tube at the sealed areas1103to form individually wrapped pads. As noted previously, further packaging operations can be performed, if desired.

For efficiency, the various sections of the apparatus of the invention should be run at compatible speeds which enable substantially continuous operation (at least 85% of the time) of all sections without interruption. That is, upstream sections should not be run at excessively high speeds which will exceed the capacity of downstream sections, nor at excessively slow speeds which will starve the downstream sections.

While the apparatus and methods have been described in the context of making interlabial pads of the type shown inFIG. 1, the features of the invention can be used to make other types of articles, absorbent or otherwise.