Method and apparatus for manufacturing elastic leg disposable diapers

A method and apparatus for elasticizing the leg areas of disposable diapers is disclosed. Portions of a continuously moving elastic ribbon are attached to a continuously moving web at spaced apart locations along the length of the web corresponding to the leg areas of a finished diapers. The web is moved over at least one arcuate surface and the portions of the ribbon that are not attached to the web are drawn through a slot in the surface so that the unattached ribbon portions separate from the web and travel a shorter path than the web. While the unattached portions of the ribbon are passing through the slot, they are clamped intermediate their ends by clamping means. While the unattached ribbon portions are held clamped, they are cut at their ends by cutting means.

FIELD OF THE INVENTION 
This invention relates to an apparatus and method for elasticizing only the 
leg areas of disposable diapers and in particular to an apparatus and 
method for removing elastic from other than the lega areas of a disposable 
diaper where it is not desired to have elastic. The subject matter of this 
application is related to that of application Ser. No. 278,619, by W. C. 
Sigl, assigned to the same assignee as that of the instant invention. 
BACKGROUND OF THE INVENTION 
Due to the improved fit and fluid sealing properties provided by leg 
elasticization, manufacturers of disposable diapers have, in recent years, 
developed various methods and apparatus for attaching elastic strips to 
the leg areas of the diapers. Because of the high speed, continuous nature 
of diaper manufacturing methods, virtually all of the commercially 
practicable processes have utilized a continuous elastic ribbon affixed to 
the diaper in the leg areas and subsequently cut either prior to or as a 
part of the severing of the continuous web into separate diapers. Typical 
of these processes and apparatus is that disclosed in U.S. Pat. No. 
4,081,301 to Buell. This patent discloses adhering of the continuous 
elastic ribbon only in discrete, intermittent areas corresponding to the 
leg areas in a finished diaper. The ribbin and the diaper are then 
simultaneously cut at the waist of the diaper when the continuous web is 
cut into separate diapers. The drawback of this process is that it is 
inefficient from the material use aspect in that it leaves an unneeded 
length of elastic attached to the diaper. Another approach to handling the 
problem is disclosed in U.S. Pat. No. 4,227,952 to Sabee. In the method of 
this patent, the elastic ribbon is continuously applied to the web, 
however, before the attachment of the ribbon to the web, the latter is 
folded in the areas of the web corresponding to the waist areas of the 
finished diapers. Consequently, the elastic ribbon is attached to the web 
only in the leg areas of the finished diaper. The elastic ribbon is then 
severed at the points opposite the folded areas of the web and the web is 
then unfolded so that elastic is only in the leg areas and the waist areas 
contain no unneeded elastic. The problem with this method and the 
apparatus used in it is that they are quite complex and difficult to 
operate at the high speeds required for commercial usefulness. 
It is a principal object of this invention to provide a method and 
apparatus for attaching a continuously moving elastic ribbon to a 
continuously moving web only in the areas of the web corresponding to the 
leg areas in finished diapers and removing the portions of the elastic 
ribbon between the attached areas in a simple and commercially practicable 
manner. 
SUMMARY OF THE INVENTION 
The objective of the invention is accomplished by providing an apparatus in 
which the elastic ribbon and web are continuously moved together and the 
ribbon attached at spaced apart locations on the web corresponding to the 
leg areas of the finished diaper. While the web and the elastic ribbon are 
moving together, the web is separated from the ribbon in the areas of the 
ribbon that are not attached to the web. The separating of the web from 
the unattached portions of the ribbon is accomplished by supporting the 
web on one or more surfaces which causes the web to move along a path 
having a longer length than the length of the path of movement of the 
unattached portions of the ribbon. To permit the unattached portions of 
the ribbon to move this shorter distance, a slot is provided in the 
supporting surface or surfaces through which the unattached ribbon 
portions pass so that separation occurs. The elastic ribbon is preferably 
subjected to elongating tension while being attached to the web so that, 
when the elastic ribbon is permitted to follow a shorter path through a 
slot, the unattached portion of the ribbon will relax and in fact move 
through the slot. While the unattached portions of the ribbon are thus 
separated from the web, both ends of the unattached portions of the ribbon 
may be cut, preferably adjacent the location of the attached portions of 
the ribbon. Although it is desirable to have the ribbon under tension so 
that its unattached portions have a greater tendency to contract and 
follow the shorter path through the slot, it is also necessary that the 
unattached portions be under tension to enable their rapid cutting. Since 
the cuts at both ends of the unattached ribbon portions may not occur 
simultaneously, a clamping means is provided to hold the unattached 
portions so that, after the first cut is made, tension is maintained at 
the end where the second cut is to be made to facilitate the making of the 
second cut. After the completion of both cuts, the ribbon may be removed.

DETAILED DESCRIPTION OF THE INVENTION 
For purposes of background, the elasticized leg disposable diaper produced 
by the apparatus and method of the invention will initially be discussed. 
Referring first to FIGS. 12 and 13, there is shown in FIG. 13 a disposable 
diaper having a topsheet 1, a backsheet 3, an absorbent pad 5 between the 
topsheet 1 and backsheet 3, a front waist area 2, a rear waist area 4, and 
a crotch area 6 intermediate the two waist areas. Leg areas 8 and 10 are 
positioned laterally of the crotch area 6 and intermediate of the waist 
areas 2 and 4. Waist fastening tapes 12 and 14 are bonded to the corner 
areas of the rear waist area 4 and are fastenable to the front waist area 
2 when the diaper is fitted to a wearer to secure the diaper on the 
wearer. Elastic strips 16 and 18 are attached substantially parallel to 
the length of the diaper in the leg areas 8 and 10 respectively, as shown 
in FIG. 12, to elasticize the leg areas of the diaper and provide a snug 
fit around the legs of a wearer. In FIG. 13, the elastic strip 16 and 18 
are shown in a relaxed condition in which they cause random pleating or 
folding of the topsheet 1 and backsheet 3. 
In FIG. 12, the only diaper components shown are the backsheet 3, the 
elastic strips 16 and 18 and adhesive lines 20 respectively attaching the 
elastic strips 16 and 18 to the backsheet 3. The backsheet 3 and the 
elastic strips 16 and 18 are shown in an extended, flat condition in which 
the elastic strips 16 and 18 are stretched. 
Referring now generally to FIGS. 1-5, apparatus is shown for supplying a 
web 28 and elastic ribbons 30 and 32, attaching the ribbons 30 and 32 to 
the web 28, and removing portions of the ribbons 30 and 32 which are not 
attached to the web 28. Apparatus for applying the absorbent pad 5, the 
waist fasteners 12 and 14, and the topsheet 2 are not shown or described 
herein inasmuch as they form no part of the present invention and may be 
of types that are well known in the art. Also, the apparatus and method 
will be described with reference to FIGS. 1-10, only with respect, in most 
instances, to continuous elastic ribbon 32 since the method and the 
operation of the apparatus is the same for both of the ribbons 30 and 32. 
In FIG. 1 is shown a web supply station 25 at which the web material 28 is 
drawn from a supply roll 31 by feed rolls 33 and 33' and fed to the 
elastic attaching station 27. At the elastic ribbon supply station 35, the 
elastic ribbon 32 is drawn from supply roll 39 by feed rolls 42 and 42'. 
The elastic ribbon 32 is then passed over a tension sensing roll 37 which, 
through feedback means (not shown), controls the speed of the feed rolls 
42 and 42' such that the elastic ribbon 32 is maintained under tension as 
it moves with the web 28 through the elastic attaching station 27 and the 
elastic removal station 29. 
At the elastic attaching station 27, adhesive nozzles 46 apply adhesive 
lines 20 to the web 28 along paths substantially parallel to the length of 
the web 28 and its direction of travel (see FIG. 12). The nozzles 46 
operate such that adhesive is applied to the web 28 only at spaced apart 
locations 24 along the length of the web 28, as illustrated in FIG. 11. 
The spaced apart locations 24 on the web 28 correspond to the leg areas 8 
and 10 of the finished diapers. Subsequent to the application of the 
adhesive lines 20 to the web 28, the web 28 and the elastic ribbon 32 are 
moved together through a pair of nip rolls 34 and 36 which press the web 
28 and the elastic ribbon 32 together to thereby attach or bond the ribbon 
32 to the web 28 only along the spaced apart locations 24 to which the 
adhesive lines 20 have been applied. Thus, there are portions 22 of the 
elastic ribbon 32 along locations 38 of web 28 which are unattached to the 
web 28 between the attached portions or strips 16 and 18 (see FIG. 12) 
along locations 24 on the web 28. As is best illustrated in FIG. 11, the 
attached elastic portions 16 and 18 of ribbons 30 and 32 on the web 28 
have ends 48 and 50 and the unattached portions 22 of ribbon 30 have ends 
52 and 54. 
After attachment of the elastic ribbon 32 to the web 28, the web 28 with 
the ribbon 32 passes between idler rolls 41, 41' as they move to elastic 
removal station 29. In the embodiment of the invention shown in FIGS. 1-5, 
the elastic removal station 29 includes a pair of web support means 80 and 
90 preferably having a pre-ferably arcuate cross-sectional shape, a ribbon 
clamping means 60, and elastic cutting means 70. The support means 80 has 
ends 81 and 85 and the support means 90 has ends 91 and 95. The support 
means 80 and 90 respectively have arcuate shaped surfaces 84 and 92. Each 
arcuate support means 80 and 90 also include a slot 82 having ends 86 and 
87 and a slot 83 having ends 88 and 89 as shown in FIGS. 2 and 3. The 
clamping means 60 comprises a pair of idler rolls 62 and 64 respectively 
positioned on opposite sides of the elastic ribbon 32 and web 28 so that 
the path of movement of the web 28 and elastic ribbon 32 passes between 
the rolls 62 and 64. As shown in FIG. 1, the clamping means 60 is 
positioned between the arcuate support means 80 and 90 adjacent their 
respective ends 85 and 91. The cutting means 70 includes a stationary hot 
knife 72 and a rotating hot knife 74 having a cutting blade 76. The 
stationary hot knife 72 is positioned adjacent the end 95 of arcuate 
support means 90 and the rotating hot knife 74 is positioned adjacent the 
end 86 of arcuate support means 80. The knives 72 and 74 are positioned 
such that they will respectively cut the leading ends 54 and the trailing 
ends 52 of unattached elastic portions 22 as the unattached elastic 
portions 22 move through the slots 82 and 83, as will be described in 
greater detail hereinafter. A vacuum means 78 is provided to remove the 
severed unattached elastic pieces 22 in the direction of the air flow as 
shown by the arrow after their severing by the cutting means 70. After 
removal of the elastic portions 22, the web 28 will have attached to it 
only elastic portions or strips 16 and 18. The web 28 and elastic strips 
16 and 18 then exit the elastic removal station 29 through the drive rolls 
56 and 58 and move toward additional stations of the diaper manufacturing 
apparatus. At the additional stations, other components will be added and 
further operations will be performed to produce a finished elasticized leg 
diaper. 
Considering FIGS. 1-5 further, as the web 28 moves over the arcuate support 
means 80, it will follow a path along the surface 84, as shown in FIGS. 1 
and 3. However, since the slot 83 is positioned in alignment with the 
location on the web 28 of continuous elastic ribbon 32, the unattached 
ribbon portions 22 of the continuous ribbon 32 are not supported by the 
surface 84 and are free to move through the slot 83 after the ribbon 
portions 22 pass the end 88 of the slot 83. The ribbon portions 22 may 
fall through the slot due to their own weight, however, if the ribbon 32 
is stretched while being applied to the web 28, the opportunity to follow 
the shorter path through the slot 83, rather than along the longer path 
over the surface 84, will result in the elastic portions 22 relaxing from 
their stretched condition and thereby moving through the slot 83. As the 
web 28 and continuous elastic ribbon 32 continue through the elastic 
removal station 29, the web and ribbon pass between the rolls 62 and 64 of 
clamping means 60 and the web 28 then continues over the surface 92 of 
arcuate support means 90. However, similarly to the movement of unattached 
elastic portions 22 as the web 28 passed over support means 80, the 
unattached ribbon portions 22 of continuous ribbon 32 will pass through 
the slot 83 of support means 90, as shown in FIG. 2. With reference to 
FIG. 4, an unattached ribbon portion 22 has reached the end 89 of slot 83 
and has been severed by the stationary knife 72 which it contacts at 
approximately the same time that it reaches the slot end 83. Meanwhile, 
the web 28 and an attached elastic strip 16 continue out of the elastic 
removal station 29 between drive rolls 56 and 58. Due to variations in the 
amount of stretch of the continuous ribbon 32 and/or the web 28 and 
variations in the timing of the apparatus related to the elastic removal 
station 29, the cutting of the trailing end 52 of the ribbon portion 22 
may take place at a different time than the cutting of its leading end 54. 
Thus, in FIG. 4, the trailing end 52 of the unattached elastic portion 22 
is shown just prior to being cut by the blade 76 of rotating knife 74 
whereas the leading end 54 of elastic ribbon portion 22 has already been 
severed. The rotating knife 74 is driven by any suitable drive mechanism 
(not shown) which will bring the knife blade 76 into contact with the 
unattached ribbon portion 22 when the trailing end 52 of a ribbon portion 
22 is at the slot end 86. In FIGS. 1 and 2, the cutting blade 76 is shown 
rotating away from the unattached ribbon portion 22 after having severed a 
trailing end 52 of a previous ribbon portion 22. In FIG. 4, the cutting 
blade 76 is shown rotating toward the ribbon end 52 just prior to severing 
the ribbon portion 22. In FIG. 5, the cutting blade 76 is shown just 
subsequent to the cutting of the ribbon end 52. 
Although the unattached ribbon portions 22 relax from their stretched 
condition when applied to the web 28 as the ribbons 22 pass through the 
slots 83, some tension nevertheless does remain in the ribbon portions 22 
after they have passed through the slots 83 and this tension is necessary 
to their rapid and effective cutting by either the stationary knife 72 or 
the rotating knife 74. However, if the ends 52 and 54 of the ribbon 
portion 22 are not cut simultaneously, the cutting of one of these ends 
prior to the cutting of the other cutting of one of these ends prior to 
the cutting of the other will result in the ribbon portion 22 relaxing 
entirely so that there will not be the necessary tension in the ribbon to 
permit the making of the second cut. The clamping means 60 is provided to 
maintain tension in the end 52 or 54 of a ribbon portion 22 that is cut 
subsequent to the cutting of the the other end. By passing the web 28 and 
the unattached ribbon portion 22 between the rollers 62 and 64 of the 
clamping means 60, the ends 52 and 54 are isolated from each other insofar 
as their tension condition is concerned. Thus, upon the severing of either 
of the ends 52 or 54, tension remains in the other end so that it also may 
be cut under tension. After severing of both ends 52 and 54 of the 
unattached ribbon portion 22, the severed ribbon portion 22 is removed by 
the vacuum removal means 78 from the elastic removal station 29. The 
beginning of the removal of the cut piece of ribbon portion 22 is shown in 
FIG. 5. 
In FIGS. 6-10 is illustrated a second embodiment of the invention in which 
at an elastic removal station 94, only a single support means 100 is 
utilized, a clamping means 110 comprises a pair of continuous, moving 
belts 112 and 114, and a cutting means 130 includes a single rotating 
cutting blade 132. As in the embodiment illustrated in FIGS. 1-5, the 
idler rolls 41 and 41' act as a guide means for the feeding of the web 28 
and continuous elastic ribbon 32 to the elastic removal station 94. Also 
similarly to the embodiment of FIGS. 1-5, the drive rolls 56 and 58 guide 
the removal of the web 28 and the elastic strips 16 and 18 from the 
elastic removal station 94 and drive the web 28 and elastic strips on to 
additional stations of the diaper manufacturing apparatus. The belts 112 
and 114 are continuously driven by any suitable power source (not shown) 
through drive chains 116, 116', drive sprockets 118, 118' and 120, 120', 
drive rolls 122, 122' and 124, 124'. A pair of idler rolls 126, 126' guide 
the belts 112 and 114 so that, as the belts rotate, corresponding 
locations on each belt converge toward each other. Guide rolls 128, 128' 
and 129, 129' hold the belts in engagement with each other. The drive 
chains 116, 116' and all of the drive sprockets and rolls comprising part 
of the clamping means 110 are supported on frame members 108, 108', shown 
only in FIG. 6. The belts 112 and 114 are respectively driven in a 
clockwise and counterclockwise direction, relative to the view of FIG. 7, 
and converge toward each other between idler rolls 126, 126' and form a 
nip 121 adjacent idler rolls 128, 128'. The cutting means 130 is also 
supported on the frame members 108, 108' and is rotatably driven from any 
suitable power source (not shown). 
The support means 100 has a preferably arcuate surface 102 and a slot 104 
having opposite ends 106 and 107. Vacuum removal means 138 is provided for 
the removal of cut pieces of unattached ribbon portions 22. 
As the web 28 passes over the surface 102 of support means 100, the 
unattached ribbon portions 22 will move through the slot 104 and follow a 
shorter path of movement than that of the web 28 between the ends 106 and 
107 of slot 104, as shown in FIGS. 6, 7 and 8. As the leading end 54 of a 
ribbon portion 22 follows the web 28 toward the slot end 107, the part of 
the ribbon portion 22 intermediate its ends 52 and 54 will move between 
the belts 112 and 114 and into the nip 121. The ribbon portion 22 is thus 
engaged and clamped or held by the clamping means 110 and drawn in a 
direction away from the path of movement of the web 28 to thereby apply 
tension to both of the ends 52 and 54 such that upon cutting of the 
leading end 54, tension will continue to be applied to the trailing end 52 
as it moves along the slot 104 toward the cutting blade 132. In FIG. 9, 
the ribbon portion 22 is shown just subsequent to its having moved into 
engagement with the cutting blade 132 and its leading end 54 having been 
severed. In FIG. 10, the trailing end 52 of the ribbon portion 22 is shown 
just subsequent to being severed from the elastic strip 16 after the 
trailing end 52 has moved through the slot with the web 28 to the cutting 
blade 132. Following the severing of the end 52, the cut piece of ribbon 
portion 22 is moved downward, relative to the view of FIGS. 6-10, by the 
continuous rotation of the belts 112 and 114 and is dropped from the 
clamping of the belts into the vacuum removal means 138. The vacuum 
removal means then removes the cut ribbon piece from the elastic removal 
station 94. 
An apparatus and a method is thus provided for elasticizing only the leg 
areas of a disposable diaper in which the elastic ribbon that is not 
needed in the waist area of the diaper is entirely removed. Due to the use 
of a clamping means which maintains tension on the ends of the elastic 
ribbon portion that is removed, the cutting of one end does not remove the 
tension from the second end and thereby prevent the second end from being 
cut. The apparatus and method are relatively simple so that they can be 
readily and economically incorporated into a high speed diaper production 
apparatus. 
It will be understood that the foregoing description of the present 
invention is for purposes of illustration only and that the invention is 
susceptible to a number of modifications or changes, none of which entail 
any departure from the spirit and scope of the present invention as 
defined in the hereto appended claims.