U.S. patent number 3,581,744 [Application Number 04/726,522] was granted by the patent office on 1971-06-01 for laminated tube structure.
This patent grant is currently assigned to Joseph A. Voss. Invention is credited to Carl W. Johnson, Joseph A. Voss.
United States Patent |
3,581,744 |
Voss , et al. |
June 1, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
LAMINATED TUBE STRUCTURE
Abstract
A three-ply, laminated tube structure for use in the fabrication
of tampon applicator devices or the like typically comprising an
external tube for carrying the tampon and an internal,
tampon-ejecting tube slidably received in the external tube. The
tube structure is particularly advantageous for use as stock
material in the manufacture of external applicator tubes of the
type having a folded, tapered forward end which opens by unfolding
during ejection of the tampon. The structure includes a glazed
tissue inner ply having a relatively high fold endurance, a thin
outer ply made of high quality, high strength paper having an
extremely smooth coating on the exterior surface, and a relatively
thick intermediate ply of short-fibered, porous, blotter-type paper
having negligible fold endurance and interposed between and bonded
to the inner and outer plies by a brittle, water soluble adhesive.
The rear extremity of the external tube is provided with a
reenforcing and gripping ring made from relatively heavy tube
stock. The internal, tampon-ejecting tube of the applicator device
may be formed from three ply tube stock similar to that used for
the external tube.
Inventors: |
Voss; Joseph A. (Denver,
CO), Johnson; Carl W. (Neenah, WI) |
Assignee: |
Voss; Joseph A. (N/A)
|
Family
ID: |
24918949 |
Appl.
No.: |
04/726,522 |
Filed: |
May 3, 1968 |
Current U.S.
Class: |
604/14;
428/34.2 |
Current CPC
Class: |
B31C
3/00 (20130101); A61F 13/26 (20130101); A61F
13/2085 (20130101); Y10T 428/1303 (20150115) |
Current International
Class: |
B31C
3/00 (20060101); A61F 13/20 (20060101); A61F
13/26 (20060101); A61f 015/00 () |
Field of
Search: |
;128/260,268,263,153--157 ;161/88 ;156/306 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Eager; Adele M.
Claims
What we claim is:
1. An hygienic applicator comprising:
a tubular member for receiving an hygienic medium, said tubular
member having a forward portion, a rear end and a longitudinal,
central axis, the forward portion of said tubular member being
pleated to form a tapered forward end having a substantially smooth
exterior surface and adapted to readily unfold during ejection of
the hygienic medium, the tubular member comprising a laminated
paper structure including:
a thin inner ply;
an outer ply, thicker than the inner ply and having a smooth
exterior surface coating; and
an intermediate ply, interposed between and bonded to the inner and
outer plies, comprising a short-fibered paper having negligible
fold resistance, said plies being formed of strips disposed
helically about the longitudinal axis in overlapping, staggered
relation;
means mounted adjacent the rear end of the tubular member for
reenforcing the tubular member and providing a gripping means
therefor; and,
means, disposed within said tubular member, for ejecting said
hygienic medium from the forward end of said tubular member.
2. An applicator, as defined in claim 1, in which:
the force required to eject the hygienic medium from the forward
end of the tubular member is about 1 pound or less.
3. An applicator, as defined in claim 1, in which:
the exterior surface coating on the outer ply is nonabsorbent and
selected from the group consisting of silicone and clay.
4. An applicator, as defined in claim 1, in which:
the paper of the inner ply is tissue comprising bleached softwood
Kraft and having greater fold endurance than each of the outer and
intermediate plies;
the paper of the outer ply comprises a major amount of bleached
hardwood Kraft and a minor amount of bleached softwood Kraft;
and
the paper of the intermediate ply comprises a major amount of
groundwood and a minor amount of bleached Kraft selected from the
group consisting of hardwood Kraft, softwood Kraft and mixtures
thereof.
5. An applicator, as defined in claim 1, in which:
the plies are bonded together by a brittle, water-soluble
adhesive.
6. An applicator, as defined in claim 1, in which:
the means for ejecting the hygienic medium comprises a three ply,
laminated tube slidably disposed, in telescoping relation, within
the rear portion of said tubular member; and,
the means for reenforcing the tubular member and providing a
gripping means therefor comprises a laminated ring bonded to the
exterior surface of the tubular member adjacent the rear end
thereof.
7. A tampon applicator comprising:
an external tube for receiving a tampon and having a folded,
tapered forward end which is readily unfolded by passage of the
tampon therethrough during ejection of the tampon, a rear end and a
longitudinal, central axis;
an internal tube, coaxially and slidably disposed in telescoping
fashion within the external tube for ejecting the tampon from the
forward end of the external tube, the internal tube having a
folded, necked down forward end for engaging the tampon, at least
said external tube comprising a laminated, helically wound paper
structure including:
a thin inner ply composed of tissue having a high fold
endurance;
an outer ply composed of paper thicker than said inner ply and
having less fold endurance and having a smooth exterior coating;
and
an intermediate ply, interposed between and bonded to said inner
and outer plies with a brittle, water-soluble adhesive, and
composed of uncoated, short-fibered blotter-type paper having
negligible fold resistance.
8. A tampon applicator, as defined in claim 7, including:
a laminated paper ring disposed about and bonded to the exterior
surface of the external tube adjacent the rear end thereof for
reenforcing the external tube and providing a gripping means.
9. A laminate comprising:
a thin, first ply comprising a single sheet having a high fold
endurance;
a thin, second ply, comprising a single paper sheet having a fold
endurance less than the first ply and having a smooth,
substantially nonabsorbent, coated surface and an uncoated surface;
and,
an intermediate ply, interposed between the first and second plies
and bonded thereto, the uncoated surface of the second ply being
adjacent the intermediate ply, said intermediate ply comprising a
single, short-fibered, absorbent paper sheet having a fold
endurance substantially less than each of the first and second
plies and a thickness greater than each of the first and second
plies.
10. A laminate, as defined in claim 9, in which:
the second ply is at least as thick as the first ply.
11. A laminate, as defined in claim 9, in which:
the second ply has a thickness up to about twice that of the first
ply.
12. A laminate, as defined in claim 9, in which:
the paper of the second ply comprises a major amount of bleached
hardwood Kraft and a minor amount of bleached softwood Kraft;
and,
the first ply comprises paper essentially of bleached softwood
Kraft.
13. A laminate, as defined in claim 9, in which:
the smooth, coated surface of the second ply is selected from the
group consisting of silicone and clay.
14. A laminate, as defined in claim 9, in which:
the paper of the intermediate ply comprises a major amount of
groundwood and a minor amount of bleached Kraft selected from the
group consisting of hardwood Kraft, softwood Kraft, and mixtures
thereof.
15. A laminate, as defined in claim 9, in which:
the paper of the second ply comprises at least 75 percent bleached
hardwood Kraft, and a minor amount of bleached softwood Kraft;
the first ply comprises paper essentially of bleached softwood
Kraft; and,
the paper of the intermediate ply comprises at least 85 percent
groundwood and a minor amount of a mixture of bleached hardwood
Kraft and bleached softwood Kraft.
16. A laminate, as defined in claim 9, in which:
the first ply is paper having a glazed surface and an unglazed
surface, the glazed surface being adjacent the intermediate
ply.
17. A laminated tubular structure for use in hygienic media
applicator devices, comprising:
a thin inner ply comprising a single paper sheet having a high fold
endurance;
a thin outer ply comprising a single paper sheet having a fold
endurance less than the inner ply and having a smooth,
substantially nonabsorbent coated exterior surface and an uncoated
interior surface; and
an intermediate ply interposed between the inner and outer plies,
the uncoated, interior surface of the outer ply being adjacent the
intermediate ply, the intermediate ply comprising a single,
short-fibered, absorbent, paper sheet having a fold endurance
substantially less than each of the inner and outer plies and a
thickness greater than each of the inner and outer plies, the
inner, outer and intermediate plies being in the form of wound
strips bonded together by adhesive.
18. A tubular structure, as defined in claim 17, in which:
the outer ply is at least as thick as the inner ply.
19. A tubular structure, as defined in claim 17, in which:
the outer ply has a thickness up to twice that of the inner
ply.
20. A tubular structure, as defined in claim 17, in which:
the paper of the outer ply comprises a major amount of bleached
hardwood Kraft and a minor amount of bleached softwood Kraft;
and,
the paper of the inner ply comprises essentially bleached softwood
Kraft.
21. A tubular structure, as defined in claim 17, in which:
the coated exterior surface of the outer ply is selected from the
group consisting of silicone and clay.
22. A tubular structure, as defined in claim 17, in which:
the paper of the intermediate ply comprises a major amount of
groundwood and a minor amount of bleached Kraft selected from the
group consisting of hardwood Kraft, softwood Kraft, and mixtures
thereof.
23. A tubular structure, as defined in claim 17, in which:
the paper of the outer ply comprises at least 75 percent bleached
hardwood Kraft, and a minor amount of bleached softwood Kraft;
the paper of the inner ply comprises essentially bleached softwood
Kraft; and,
the paper of the intermediate ply comprises at least 85 percent
groundwood and a minor amount of a mixture of bleached hardwood
Kraft and bleached softwood Kraft.
24. A tubular structure, as defined in claim 17, in which:
the inner ply has a glazed surface and an unglazed surface, the
glazed surface being adjacent the intermediate ply.
25. A laminated tubular structure for use in hygienic media
applicator means, said tubular structure having a longitudinal,
central axis and comprising:
a thin inner ply;
an outer ply, thicker than said inner ply and comprising paper
having a smooth, substantially nonabsorbent exterior coating and an
uncoated, absorbent interior surface;
an intermediate ply, interposed between the inner ply and the
interior surface of the outer ply and comprising an uncoated,
blotter-type, short-fibered, porous paper, thicker than each of the
inner and outer plies, said inner, outer and intermediate plies
comprising strips helically oriented relative to the longitudinal
axis of the tubular structure and wound in overlapping, staggered
relation and bonded together by adhesive.
26. A tubular structure, as defined in claim 25, in which:
the exterior coating on said outer ply is selected from the group
consisting of silicone and clay.
27. A tubular structure, as defined in claim 25, in which:
the inner ply comprises paper tissue having a fold endurance
substantially greater than each of the outer and intermediate
plies.
28. A tubular structure, as defined in claim 27, in which:
the inner ply fiber is substantially 100 percent bleached softwood
Kraft, and has a caliper between about 0.002 and 0.003 inch;
the outer ply fiber is approximately 76 percent bleached hardwood
Kraft and approximately 24 percent bleached softwood Kraft, and has
a caliper between about 0.003 and 0.004 inch;
the intermediate ply fiber is approximately 7 percent bleached
softwood Kraft, approximately 6 percent bleached hardwood Kraft and
approximately 87 percent groundwood, and has a caliper between
about 0.005 and 0.006 inch.
29. A tubular structure, as defined in claim 25, in which:
the adhesive is brittle and water-soluble.
30. A laminated applicator tube, for containing an hygienic medium,
said tube having a forward end, a rear end and a longitudinal
central axis, comprising:
an inner ply having a high fold endurance;
an outer ply having a fold endurance less than the inner ply and
formed of a paper sheet having a smooth, substantially nonabsorbent
exterior surface; and,
an intermediate ply, interposed between and bonded to the inner and
outer plies and comprising a blotter-type, short-fibered paper
having negligible fold resistance, said plies being formed of
strips disposed concentrically about the longitudinal axis in
overlapping fashion relative to one another, the forward end of
said tube including tightly abutting pleats forming a generally
tapered configuration, said tapered forward end being adapted to
readily unfold as the hygienic medium is ejected from the
applicator tube.
31. A tubular structure, as defined in claim 30, in which:
the force required to eject the hygienic medium from the forward
end of the applicator tube is approximately 1 pound or less.
32. A tubular structure, as defined in claim 30, in which:
the inner ply comprises tissue paper having a glazed surface and an
unglazed surface and a fold endurance substantially greater than
each of the outer and intermediate plies, the glazed surface of the
inner ply being disposed adjacent the intermediate ply.
33. A tubular structure, as defined in claim 30, in which:
the outer ply has a thickness up to about twice that of the inner
ply; and
the intermediate ply has a thickness greater than each of the inner
and outer plies.
34. A tubular structure, as defined in claim 30, in which:
the paper of the outer ply comprises a major amount of bleached
hardwood Kraft and a minor amount of bleached softwood Kraft;
and
the inner ply is formed of paper comprising essentially bleached
softwood Kraft.
35. A tubular structure, as defined in claim 30, in which:
the substantially nonabsorbent exterior surface of the outer ply is
a coating selected from the group consisting of silicone and
clay.
36. A tubular structure, as defined in claim 30, in which:
the paper of the intermediate ply comprises a major amount of
groundwood and a minor amount of bleached Kraft selected from the
group consisting of hardwood Kraft, softwood Kraft, and mixtures
thereof.
37. A tubular structure, as defined in claim 30, in which:
the paper of the outer ply comprises at least 75 percent bleached
hardwood Kraft, and a minor amount of bleached softwood Kraft;
the inner ply comprises paper essentially of bleached softwood
Kraft; and
the paper of the intermediate ply comprises at least 85 percent
groundwood and a minor amount of a mixture of bleached hardwood
Kraft and bleached softwood Kraft.
38. A tubular structure, as defined in claim 37, in which:
the inner ply fiber is substantially 100 percent bleached softwood
Kraft and has a caliper between about 0.002 and 0.003 inch;
the outer ply fiber is approximately 76 percent bleached hardwood
Kraft and approximately 24 percent bleached softwood Kraft and has
a caliper between about 0.003 and 0.004 inch; and,
the intermediate ply fiber is approximately 7 percent bleached
softwood Kraft, approximately 6 percent bleached hardwood Kraft and
approximately 87 percent groundwood, and has a caliper between
about 0.005 and 0.006 inch.
39. A tubular structure, as defined in claim 30, in which:
the plies are bonded together by a water-soluble brittle glue.
40. A tubular structure, as defined in claim 30, which
includes:
a ring bonded to the exterior surface of the tubular structure
adjacent the rear end thereof, said ring comprising a multi-ply
structure.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to improved tampon
applicator devices, and particularly to improved tube structures
for use in said devices and to methods and apparatus for
manufacturing said improved tube structures.
U.S. Pat. Nos. 3,204,635 and 3,358,354, issued to the present
inventors on Sept. 7, 1965 and Dec. 19, 1967, respectively,
disclose an improved catamenial tampon applicator utilizing an
external tube having a tapered forward end and an internal,
tampon-ejecting tube, slidably received within the outer tube, and
a method for forming the forward ends of these tubes. The tapered
end of the external tube facilitates insertion of the applicator
into the vagina and comprises a plurality of dovetailed folds or
pleats which provide a structure easily opened from the inside,
thereby permitting the user to eject the tampon without having to
exert undue force. The internal, tampon-ejecting tube includes a
reduced diameter, tampon-engaging forward end structured similarly
to the forward end of the external tube in that it constitutes a
plurality of folded or pleated sections.
Copending application Ser. No. 690,001, filed by the present
inventors on Dec. 12, 1967, and which is a continuation-in-part of
application Ser. No. 464,127 filed June 15, 1965 which issued as
the aforementioned U.S. Pat. No. 3,358,354, discloses an automatic
applicator tube forming or shaping unit. By means of this
apparatus, the forward end of the tube is initially crimped and
then compressed into its final configuration by an appropriately
shaped die which forms tightly abutting pleats. In the fabrication
of the external tampon applicator tube, the compressed forward end
of the tube is "exercised" to weaken the fold creases. This is
accomplished by expanding the forward end of the tube to
substantially its original cylindrical shape by the successive
insertion of increasingly larger punches into the front end of the
tube. Alternatively, the tube expansion may be accomplished in a
single step. In this case, the exercising punch is moved forwardly
through the front end of the tube from the inside rather than by
insertion of one or more punches from the outside. Following its
expansion, the forward end of the tube is recompressed into its
final, tapered form. The folding, unfolding and refolding works the
creases so as to provide a substantially lifeless hinge. Thus,
there is no tendency for the forward end of the tube to reopen and
there is little resistance when the tampon is moved through the
forward end during ejection.
It will be appreciated that the yieldability of the material
forming the external tube is an important factor not only with
respect to formation of the pleats but also because it is desirable
from the standpoint of consumer acceptance that the axial force or
thrust necessary to spread open the forward end and eject the
tampon be minimized. More specifically, it is desirable that the
required axial force or thrust be reduced to 1 pound or less.
Furthermore, upon opening of the forward end, any paper residue,
dust or debris dislodged from the creases cannot be permitted to
reach the vagina either directly or by way of the tampon.
It will also be appreciated that the provision of a thin-walled
external tube is most desirable because in this way the overall
diameter of the applicator can be minimized while maximizing the
size of the tampon accommodated therein. The result is a product
which has a pleasing appearance, inserts easily and simultaneously
incorporates a tampon having the greatest fluid absorbing
capabilities and provides the required yieldability to facilitate
formation of the pleated forward end and opening thereof.
By fastening a ring about the external tube adjacent the rear
extremity thereof, as disclosed in U.S. Pat. No. 3,347,234, issued
on Oct. 17, 1967 to J. A. Voss, one of the inventors herein, the
external tube may be reenforced to minimize deformation as the
result of gripping pressure during use of the applicator. The ring
also provides a means for securely gripping the applicator to
assure proper orientation during insertion. Application Ser. No.
690,001, referenced earlier, discloses apparatus for automatically
applying the rings to the external tubes.
Certain tampon applicators presently available are fabricated of
plastic material, such as polyethylene. Although these applicator
tubes are stronger than those made of materials such as paper, they
have disadvantages which makes their use decidedly less desirable.
For example, plastic applicators are obviously not disposable in a
completely sanitary fashion such as by flushing down a toilet.
Further, plastic applicators have thicker walls than paper
applicators and thus tend to be more bulky and, like all open-ended
applicators, insertion is often difficult.
The manufacture of multilayer tubes by winding strips of paper in
overlapping, helical orientation on a fixed mandrel is well known.
However, certain problems arise when the winding of very thin
strips is undertaken. Thus, the tension of the strips, as they are
wound about the mandrel, must be accurately controlled so as to
assure uniformity of the final product. Further, excessive tension
may cause breakage of thin strips or cause the winding machine to
come to a complete stop. Hence, it is required that each paper
strip be under relatively low, constant tension.
Because the strips of paper are wound under tension, substantial
frictional drag forces are generated between the innermost surface
of the tube and the mandrel as the tube rotates about and advances
along the mandrel. This may result in torsional distortion and
tearing of the tube. Although various liquid oils, such as
petroleum lubricating oil, are commonly used as lubricants in
helical tube winding, these are not suitable for winding thin paper
strips because of the tendency to be absorbed completely by the
paper and to cause discoloring of the paper during storage. In
addition, petroleum based lubricating oil is a medium which
promotes bacterial growth and is therefore not suitable as a
lubricant for use in the winding of tampon applicator tubes.
SUMMARY OF THE INVENTION
According to a broad aspect of the present invention, a
thin-walled, laminated tubular structure is provided which forms
the tube stock from which hygienic media applicator devices, such
as tampon applicators, may be fabricated. A three-ply construction
is utilized including a thin outer ply which is opaque and has high
whiteness, high strength and stiffness and an extremely smooth,
coated exterior surface. The tubular structure further includes an
inner ply which is thinner and less strong than the outer ply but
will not readily fail as a result of repeated folding. Interposed
between and bonded to the outer and inner plies is an intermediate
ply comprising uncoated, short-fibered, blotter-type paper, thicker
and substantially weaker than either the inner or outer ply and
able to resist very little folding. The intermediate ply is further
characterized by relatively low density and high porosity to allow
rapid, complete impregnation and wetting of the bonding adhesive
during fabrication of the tube structure.
The composite structure described above is particularly useful as
stock material for an external applicator tube of the type
disclosed in U.S. Pat. No. 3,204,635 because the formation of the
folded end is facilitated while the axial force required to open
the folded end when ejecting the tampon is minimized. Further, the
inner ply serves to trap and holds any glue particles and paper
dust or fibers dislodged from the intermediate ply during unfolding
of the forward end when the tampon is ejected and thereby prevents
these particles and fibers from reaching the tampon and the
vagina.
The internal applicator tube may also be fashioned from tube stock
having the above-described laminated structure. By bonding together
the various plies with a water soluble glue, the applicator device
becomes completely disposable in a sanitary fashion such as by
flushing down a toilet.
Another aspect of the present invention pertains to a method for
making the described laminated applicator tubes in which strip
material is constantly drawn from supply reels and helically wound
about a fixed mandrel in overlapping, staggered relation. The
method includes the application of a lubricating medium, in the
form of lycopodium powder, to the surface of the strip material
which engages and rides upon the surface of the fixed mandrel. The
method for making the applicator tube stock also includes the step
of applying a liquid adhesive to all surfaces of the blotter-type
strip forming the intermediate ply and removing excess adhesive
from the faces of the strip to provide equal thicknesses of
adhesive on both faces, thereby precluding slippage between
adjacent strips during winding and assuring the production of a
uniform product. To further insure that the thicknesses of the
adhesive layers on the faces of the intermediate strip are uniform
and equal, the strip path is moved through a 180.degree. twist
between the point of removal of the excess adhesive and the
mandrel.
According to still another aspect of the present invention,
apparatus for supplying strip material to the tube-winding
apparatus under constant, low tension is provided. Broadly, the
strip supplying apparatus includes a rotatable platform, which may
be in the form of a relatively high inertia turntable, for
supporting a supply roll of the strip material, and a frictional
drag or brake device engaging a surface, such as the outer
periphery, of the rotatable platform. The strip supplying apparatus
includes a means for sensing strip tension and applying to the
frictional drag device a force corresponding to strip tension. When
the strip tension increases, the frictional drag device is biased
away from the surface of the rotatable platform to decrease the
frictional drag force. The force derived from strip tension is
counteracted by a biasing force applied to the frictional drag
device, which tends to move the drag device toward the surface of
the rotatable platform. The result is a simple mechanical feedback
system which accurately controls tension at a level determined by
the biasing force, which, in an elementary form, may be derived
from a weight connected to the drag device.
Another aspect of the present invention pertains to a tube winding
apparatus which includes means for applying liquid adhesive to the
strip material which is wound about the mandrel. Generally, the
adhesive applying means includes a chamber or spout through which
the strip material is threaded. Liquid adhesive, which has been
heated to reduce its viscosity, is supplied to the spout under
pressure. All surfaces of the strip are exposed to the adhesive
within the spout and the strip is therefore quickly wetted and
completely impregnated. The adhesive-applying means further
includes a pair of opposed, spaced, rounded doctor surfaces between
which the strip material passes after it leaves the spout and which
remove excess adhesive from the faces of the strip to leave
uniform, equal thicknesses of adhesive on the strip. The doctor
surfaces may be circular in cross section, having a radius of at
least one-eighth inch.
Still another aspect of the present invention pertains to an
apparatus for dispensing metered amounts of lycopodium powder onto
the surface of the strip material which engages the fixed mandrel.
Broadly, the dispensing apparatus includes a container for holding
a supply of the powder and having in its lower portion a
funnel-shaped section converging downwardly toward an opening
through which the powder is free to pass. The outer periphery of a
cylindrical wheel, mounted within a cylindrical cavity underneath
the funnel-shaped portion, communicates with the opening at the
lower end of the funnel-shaped section and is rotated by a motor so
as to remove lycopodium powder from the container and deliver it to
the strip material passing immediately underneath the lower
extremity of the curved periphery of the cylinder. The clearance
between the outer surfaces of the cylinder and the cylindrical
cavity within which the cylinder rotates is uniform and
approximately 0.002 inch so that exact metered amounts of
lycopodium powder are dispensed.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages of the present invention will be
apparent from a study of the following detailed description and the
accompanying drawings, in which:
FIG. 1 shows a longitudinal, cross section view of a tampon
applicator device;
FIG. 2 shows a perspective view, partially broken away, of the
external tube of the applicator device of FIG. 1;
FIG. 3 shows an enlargement of a portion of the longitudinal cross
section view of FIG. 1;
FIG. 4 shows a plan view of a portion of a tube winding apparatus
used in the manufacture of applicator devices such as depicted in
FIGS. 1--3;
FIG. 5 shows an end elevation view of a portion of the apparatus of
FIG. 4;
FIG. 6 shows an enlargement of a portion of the plan view of FIG.
4;
FIG. 7 shows an enlargement of a portion of the plan view of FIG. 4
in which the strip material used to form the tube is omitted;
FIG. 8 shows a perspective view of an apparatus for supplying strip
material to a tube winding apparatus under substantially constant,
low tension;
FIG. 9 shows a plan view of the apparatus of FIG. 8;
FIG. 10 shows a partially exploded, partially schematic,
perspective view of an adhesive applying apparatus;
FIG. 11 shows a longitudinal, cross section view of a portion of
the adhesive applying apparatus depicted in FIG. 10;
FIG. 12 shows a side elevation, cross section view of a powdered
lubricant dispensing apparatus; and,
FIG. 13 shows a front elevation, cross section view of the
dispensing apparatus of FIG. 12.
DETAILED DESCRIPTION OF THE INVENTION
Although the description which follows will be directed to
applicators for insertion of tampon devices, it will be appreciated
that other hygienic or medicinal media, such as suppositories, may
be dispensed by applicators of the type discussed.
Referring to FIG. 1, a tampon applicator device 10 is depicted. The
device 10 has a longitudinal axis 12 and includes an external tube
14, an internal, tampon-ejecting tube 16 disposed in telescoping
fashion within the rear portion of the external tube 14, and a
tampon 18 contained within the forward portion of the external tube
14.
The external tube 14 has a relatively thin, laminated wall
structure, which will be described in detail below, and a forward,
tapered end 20 making insertion of the external tube 14 into the
vagina easy and rapid, without discomfort or irritation to the
user. The forward extremity of the tampon 18 is shaped to conform
to the tapered configuration of the interior of the forward end 20
of the tube 14.
A reenforcing and gripping ring 22 is secured about the exterior
surface of the external tube 14 in accordance with the teachings of
U.S. Pat. No. 3,347,234, mentioned earlier. The rear extremities of
the tube 14 and the ring 22 are flush to provide a relatively large
surface area and eliminates the sharp rear edge of the tube 14.
The forward end 20 of the external tube 14 comprises a series of
overlapping, tightly abutting pleats or folds, the structural
aspects and formation of which are described in detail in
aforementioned U.S. Pat. Nos. 3,204,635 and 3,358,354 and
application Ser. No. 690,001. Briefly, the forward end of the
external tube 14 is initially crimped or partially folded and then
compressed within a generally cone-shaped die to fully hold the
tube end. Next, the folded end is "exercised." The object of this
operation is to weaken the fold lines and thereby reduce the axial
force required to eject the tampon during insertion. The
"exercising" operation provides a substantially lifeless hinge at
each of the folds or creases and almost completely precludes what
would otherwise be a tendency on the part of the folded forward end
to spring back to its original shape. The ultimate goal is a
completely dead soft fold. Broadly, "exercising" is accomplished by
substantially fully unfolding or expanding the completely folded
tube end and then refolding and compressing the tube end within a
generally cone-shaped die. During this final step, a centrally
located pin, mounted within the die, is used to form a small
aperture 24 in the tip of the tube 14 to facilitate the subsequent
unfolding during use by assuring that the folds are symmetrically
disposed about the longitudinal axis 12 of the tube.
The foregoing underlines the need for a tube material which will
readily assume the desired tapered shape without "spring back" or
undue resilience and which will provide a tube end which may be
opened with a minimum amount of force during ejection of the
tampon.
Referring to FIGS. 2 and 3, it will be seen that the external tube
14 comprises a composite, laminated structure including an outer
ply 26, an intermediate ply 28 and an inner ply 30. As will be
described in greater detail below, the tube 14 is formed by
continuously winding three strips of paper 26a, 28a and 30a in
overlapping, helical fashion about a mandrel by a movable belt
wrapped about the mandrel. Helical butt joints 32, 34 and 36 are
thereby produced in plies 26, 28 and 30, respectively. In
accordance with one example of the external tube 14, the strips
26a, 28a and 30a, forming the plies 26, 28, and 30, respectively,
are about 11/8 inches wide. Because the diameters of the plies are
progressively larger toward the outside of the tube, the
intermediate strip 28a is about 0.015 inches wider than the inner
strip 30a and the outer strip 26a is about 0.015 inch wider than
the intermediate strip 28a to assure that the edges of the strips
butt together.
The width of the strip material is not critical; for a given width,
the adjustments which must be made in the winding operation will be
evident to those skilled in the art. One factor which must be
considered is the width of the drive belt winding the strip
material about the mandrel. It is preferable that the widths of the
belt and strips be equal so that the complete width of the strip
will be under compression.
Much of the strength of the tube is determined by the use of three
plies rather than two. It will be evident that if a two-ply
construction were employed, only a single layer of paper would be
present at a given butt joint to provide structural strength. Some
weakness, of course, could be avoided if the butt joint gaps were
reduced to substantially zero. However, a very small gap between
the adjacent edges of the strip must be assumed because it is
impossible, from a practical standpoint, to reduce the gap to zero
along the entire length of the joint.
It is further important to note that the strips used to form the
three plies are wound in staggered, overlapping relation with
respect to one another. In this way, the spiral butt joint of any
one ply will be displaced from, that is, out of registry with, the
butt joint of any other ply. This arrangement provides maximum
strength in the wall of the tube.
The outer ply 26 of the tube 14 is made from high quality, opaque
paper having a caliper or thickness ranging between 0.003 and 0.004
inch. The exterior surface of the outer ply 26 is provided with a
smooth, nonwettable coating 38. The coating may be of the "earthen"
clay kind typically employed in the manufacture of high quality
packaging to give a glossy appearance. Alternatively, a silicone
coating may be used. The function of the coating 38 is to provide
the exterior surface of the tube 12 with an extremely smooth,
slippery texture which is nonabsorbent. The outer ply 26 may also
be characterized as having high whiteness and high strength, with
greater stiffness than the intermediate and inner plies 28 and
30.
The ply 26 has a fiber composition comprising approximately 76
percent bleached hardwood Kraft and 24 percent bleached softwood
Kraft. The basis weight of the paper forming the outer ply 26 is
about 17 to 18 pounds per 1,000 square feet with a density of
approximately 60 pounds per cubic foot.
As already mentioned, the fold strength of the material
constituting the exterior tube 14 is significant because the
forward end 20 must not only be easily formed into the desired
tapered configuration but must also open easily under the influence
of a small, axially directed tampon-ejecting force, preferably
about 1 pound or less. In the example under discussion, in terms of
number of double folds to failure, the fold strength of the outer
ply paper in the machine direction is approximately 75 double folds
and in the cross machine direction, 48 double folds. [Fold
endurance data for the outer ply 26, as well as for the
intermediate and inner plies 28 and 30, were obtained using an MIT
(Massachusetts Institute of Technology) Folding Endurance Paper
Testing Machine manufactured by the Tinius Olsen Testing Machine
Company of Philadelphia, Pa. Tests were in accordance with ASTM
(American Society of Testing Materials) specification D-643.]
Because all of the plies are wound in a helical direction, the fold
lines in the tapered forward end of the finished applicator tube,
directed generally parallel with the longitudinal axis 12, will not
be parallel to either the machine or cross machine direction. The
actual fold strength will therefore lie somewhere between the
machine and cross machine fold strengths and may be presumed to be
approximately the average of the two. It should be noted however,
that the finished assembly comprising all three plies, bonded
together by suitable adhesive, will not have fold endurance
characteristics which can be readily computed from the endurance
characteristics of the individual plies before being bonded
together. Thus, the fold endurance data is solely for the purpose
of specifically identifying and describing by physical
characteristics the material that is used for individual plies
prior to being bonded together.
In accordance with the Sheffield Paper Smoothness Test, the
exterior coating 38 on the outer ply 26 provided 8.4 units of
airflow denoting an extremely smooth surface. For this test, the
coating 38 comprised glazed, "earthen" clay. In contrast, the
unglazed interior surface of the outer ply 26 provided 84.2
Sheffield flow units.
The intermediate ply 28 of the external tube 14 is an uncoated,
relatively thick, blotter-type, short-fibered paper of relatively
poor quality. As a result of the shortness of the constituent
fibers, this ply has the important attribute of being able to
resist very little folding. The approximate fiber composition is 7
percent bleached softwood Kraft, 6 percent bleached hardwood Kraft
and 87 percent groundwood, the latter being a very short fiber. The
approximate distribution of fiber length in the intermediate ply 28
is as follows: 76 percent short (0.0 to 1.0 mm.), 21 percent medium
length (1.0 to 2.5 mm.) and 3 percent long (2.5 to 4.0 mm.).
In the example under discussion, the basis weight of the
intermediate ply 28 is about 15.5 pounds per 1,000 square feet with
a density of about 34.5 pounds per cubic foot. This relatively low
density indicates high porosity which makes the intermediate ply
particularly liquid absorbent. The caliper or thickness of the
intermediate ply 28, in the example under discussion, falls within
the range of about 0.005 to 0.006 inch. As mentioned, the fold
endurance is extremely low, requiring only 7.4 double folds to
failure in the machine direction and four double folds to failure
in the cross machine direction utilizing the MIT Folding Endurance
Paper Testing Machine referenced earlier. When adhesive is applied
to both faces of the paper strip used to form the intermediate ply
28 and allowed to set, the fold endurance is substantially
decreased, averaging one double fold to failure. Thus, it may be
presumed that in the final product, as a result of the exercising
operation, the intermediate ply 28 is probably fractured at the
fold lines.
Another highly significant property of the paper forming the
intermediate ply 28 is its tensile strength. In the tampon
applicator tube stock manufacturing technique to be described in
detail later, the strips forming the plies 26, 28, and 30, are
drawn and wrapped about a fixed mandrel by means of a movable belt
encircling the mandrel. It is important to maintain a constant, low
tension on each of the strips to produce tubes of uniformly high
quality and keep the winding machine operating properly. Whereas
the strips forming the outer and inner plies 26 and 30 do not
present any particular problem with respect to breakage during
winding because of their relatively high strength, the intermediate
ply strip material, because of its relatively low grade, is
susceptible to breakage. The dry tensile strength of the paper
employed for the intermediate ply 28 is approximately 14.1 pounds
per inch width in the machine direction and 7.4 pounds per inch
width in the cross machine direction. The wet tensile strength,
following a 30-second soak in water, is 2.36 pounds per inch width
in the machine direction. The foregoing data is based upon tensile
strength tests performed in accordance with ASTM standard
D828-60.
The inner ply 30, in accordance with one example, may comprise
glazed tissue between 0.002 and 0.003 inch thick. The fiber type is
substantially 100 percent bleached softwood Kraft and the paper has
a basis weight of 9.38 pounds per 1,000 square feet and a density
of about 50 pounds per cubic foot. The inner ply 30 functions not
only to provide added strength to the final product, but also to
trap debris in the form of particles or dust which may be dislodged
from the intermediate ply 28 during unfolding. It is thus necessary
that the inner ply 30 have sufficient fold endurance to preclude
the possibility of failure at the crease lines. Inner ply material
having the properties described above endured 993 double folds
before failing in the machine direction and 471 double folds in the
cross machine direction.
The inner ply tissue is provided with a glazed exterior side which
is adhered to the intermediate ply 28 and which is quite smooth,
having a Sheffield smoothness of 94 units of airflow. The unglazed
interior surface of the inner ply 30 is somewhat rougher, providing
225 units of airflow under the Sheffield smoothness test. The dry
tensile strength, determined in accordance with ASTM standard
D828-60, is 18.4 pounds per inch width in the machine direction and
11.9 pounds per inch width in the cross machine direction. The
Gurley Stiffness Test performed on this paper indicated 33.52
stiffness units in the machine direction and 31.52 stiffness units
in the cross machine direction.
The foregoing data, pertaining to the paper constituting the
various plies, relate to specific examples; variations in the
different parameters can, of course, be tolerated. For example,
with respect to basis weight, caliper, and densities, variations of
.+-.25 percent are acceptable.
In the fabrication of the applicator tubes, liquid adhesive is
applied to the strip 28a forming the intermediate ply 28 in a
manner to be described. The strip 28a, because of its blotter-type
nature, readily and completely absorbs the adhesive. The adhesive
is preferably of the type that dries very brittle, so that it
fractures readily and adds little or no resistance to opening of
the tapered front end of the tube 14 when the tampon is ejected.
This adhesive is further preferably water soluble to enable
complete and rapid disposal of the applicator device in water. The
plies 26, 28 and 30 thus quickly separate and soften as a result of
becoming saturated with water. Subsequent disintegration of the
paper precludes clogging of pipes and sewage systems. A
commercially available adhesive which meets the foregoing
requirements is adhesive No. 2706 manufactured and sold by Swift
& Company of Chicago, Ill. This adhesive is light colored and
has a dextrin base. At room temperature, it is relatively viscous,
of the order of 50 poises. When heated, however, it is decidedly
less viscous.
The internal tube 16 may be formed from three-ply tubular stock,
including outer ply 40, intermediate ply 42 and inner ply 44,
similar to that described in connection with the external tube 14.
The criteria which must be met by the internal tube 16 is obviously
not as stringent as that which must be met by the external tube 14,
in which the formation of the forward end 20 must be facilitated
and the end 20 must unfold with minimum resistance during ejection
of the tampon. However, the three-ply construction described in
connection with the tube 14 not only provides a similarly
structured tube 16 with high strength but facilitates the formation
of the pleated, reduced diameter, forward end 17, which formation
is described in greater detail in the aforementioned U.S. Pat. No.
3,358,354 and the copending application Ser. No. 690,001. Use of an
internal tube 16 having the described construction including a
smooth exterior coating, also helps minimize the force required for
ejection of the tampon because the tube 16 slides easily, with
minimal frictional resistance, within the external tube 14.
The reenforcing ring 22 is preferably made from tube stock which is
heavier than that used for the external and internal tubes 14 and
16. The ring tube stock can, according to one example, comprise
three plies 46, 48 and 50 of hard, unfinished paper about 0.006
inches thick. This structure not only provides substantial
reenforcing, but provides a good gripping surface for the finger.
The ring, in the example under consideration, is three-sixteenths
inches long and its rear edge is positioned flush with the rear
extremity of the external tube 14 thereby eliminating what would
otherwise be a sharp edge by providing a relatively large surface
area against which the finger, used to advance the internal tube 16
during ejection of the tampon, comes to rest.
Turning now to FIGS. 4--13, there is shown a tube winding machine
51 of the well-known type in which a plurality of paper strips are
helically wound around a fixed mandrel by an endless, movable belt
wrapped about the mandrel. The belt engages the strips to wind them
into a continuous tube advanced along the mandrel, the tube
subsequently being cut to the desired lengths.
The machine 51 comprises generally a winding apparatus 52, means,
designated generally by reference numeral 54, for supplying strip
material to the winding apparatus 52 under constant, low tension,
adhesive applying means 56, lubricating medium dispensing means 58
and tube cutting means 60.
Turning now to FIGS. 4--7 in particular, the tube winding apparatus
52 includes a mandrel 62 having a circular cross section and
supported in horizontal, cantilevered fashion by a chuck 64. The
chuck 64 is secured to a shaft 66 supported by a pair of posts 68
extending upwardly from a base 70.
A drive belt 72, under tension, encircles the mandrel 62 in a
helix, as best shown in the enlarged views of FIGS. 6 and 7. As
already stated, the width of the belt 72 is preferably equal to the
width of the strips to be wound so that the strips are subject to
pressure across their entire widths.
The belt 72 is looped at each end about a drive pulley 74 driven by
an electric motor 76 through an appropriate transmission 78. The
pulley 74, motor 76 and transmission 78, are mounted on a support
plate 80 mounted for sliding, horizontal movement along a pair of
vertically spaced, horizontally oriented guide shafts 82 carried by
a central upright member 84. The shafts 82 terminate, at their
outer ends, in end plates 83. The upright 84 is secured to the base
70 by a single bolt and nut fastener 86. By loosening the fastener
86, the belt drive mechanism may be rotated to the appropriate
angle relative to the mandrel 62. For purposes of winding
applicator tubes disclosed herein, an angle of about 35.degree. is
satisfactory although this may be varied in accordance with
specific requirements.
The position of the support plates 80 along the guide shafts 82,
and hence, the tension of the belt 72, may be adjusted by means of
lead screws 88 supported at their opposite ends by the central
member 84 and the end plates 83. The lead screws 88 threadedly
engage the support plates 80 and a hand wheel 90 secured to the
outer end of each lead screw 88 provides the desired translation of
the support plate 80.
As the tube stock, designated by reference numeral 92, formed by
the belt 72, advances along the mandrel 62 (in a direction to the
right as viewed in FIG. 4), substantial frictional resistance or
drag between the tube stock 92 and the mandrel 62 may be
encountered. In the case of very thin walled tubes, such as those
forming part of the present invention, twisting and tearing of the
tube may result. To eliminate this problem, the mandrel 62 is
undercut, that is, provided with a reduced diameter portion 62a, as
shown in the FIGS. 6 and 7, so that only light, intermittent
contact is present along this portion between the mandrel and the
tube stock. According to one example of a mandrel used for forming
tube stock for the external tube 14, the larger diameter of the
mandrel is 0.578 inch and the undercut portion has a diameter of
0.547 inch.
Although the tube winding machine 51 will be described in detail in
connection with the manufacture of tube stock for the external tube
14, it is to be understood that the fabrication of stock for the
internal tube 16 and the reenforcing ring 22 are accomplished in
substantially identical fashion.
In the manufacture of tube stock for the external tube 14, the
three strips 26a, 28a, and 30a are fed simultaneously and
continuously onto the mandrel 62 by the belt 72. The strip 26a
forms the outer ply 26 of the finished tube 14, the strip 28a the
intermediate ply 28 and the strip 30a the inner ply 30. Although
all of the strips may be fed from one side of the mandrel 62, in
the apparatus under consideration, the inner strip 30a is fed from
the side opposite the strips 26a and 28a to eliminate interference
between the adhesive applying means 56 and the lubricant dispensing
means 58.
The various strips are fed onto the mandrel 62 in overlapping,
staggered relation. Appropriate means (not shown) are provided for
guiding and maintaining the proper overlapping relationship between
the individual strips. The amount of overlap is not critical so
long as the butt joint in any one play is not in alignment with the
butt joint in the final product. The amount of overlap between the
outer ply and the intermediate ply can be the same as that between
the intermediate and inner plies or it can be different. For strips
11/8 inches wide, overlaps may typically range from one-fourth
inches to one-half inches.
The tension of the strips 26a, 28a, and 30a are of substantial
importance from the standpoint of producing tubes having uniform
wall thickness, diameter and quality. It is essential that the
strips 26a, 28a, and 30a be wound onto the mandrel under
substantially constant, low tension. For the strip material
described, it has been found that tensions of 6 to 8 pounds on the
outer strip 26a, 6 to 8 ounces on the intermediate strip 28a and
about 2 pounds on the inner strip 30a are satisfactory. These
values apply for a relative humidity of approximately 25 percent.
Significant changes in tension result from changes in humidity;
therefore, the tubes described herein are normally wound in a
controlled humidity environment so that the required tensions can
be accurately determined and maintained.
Referring to FIGS. 8 and 9, the means 54, for supplying the strip
material to the mandrel under constant, low tension will now be
described. Each strip may be supplied by one of the means 54, the
individual supply means being adjusted to provide the necessary
tension for the particular strip being supplied.
The strip supplying means 54 comprises a baseplate 100 supported by
a suitable frame 102 and carrying a spindle 104 freely rotatable
within a bearing (not shown) mounted in the baseplate 100. Attached
to the spindle 104 is a rotatable means or turntable 106 in the
form of a circular, relatively heavy metal plate. A portion of the
spindle 104 projects upwardly from the horizontal turntable 106 for
receiving a supply roll 108 of strip material. The supply roll 108
is keyed to the spindle 104 so that the spindle 104, turntable 106
and supply roll 108 rotate together. The mass of the turntable 106
is relatively high compared to that of the supply roll 108 and once
brought up to speed, the turntable tends to maintain a constant
angular velocity irrespective of changes in the diameter of the
unwinding supply roll 108 and irrespective of short term, that is,
high frequency variations in supply roll tension.
Pivotally mounted on the frame 102 at point 110, and positioned
adjacent the outer periphery 106a of the turntable 106, is an arm
112 carrying at one end a frictional drag means 114 for engaging
the outer periphery 106a. The frictional drag means 114 includes a
small shoe 116, made of rubber or other high friction material,
carried by fastener means 118 secured to the arm 112. The fastener
means 118 permits lateral adjustments to be made to the position of
the shoe 116 relative to the arm 112. The pivot point 110 of arm
112 is relatively close to the end of the arm carrying the
frictional drag means 114 so that a substantial mechanical
advantage is provided.
Mounted on the other end of the arm 112 is an upright, freely
rotatable roller 120 about which the strip material is looped. The
function of the roller 120 is to sense the tension of the strip
material and to transmit this tension force to the long end of the
arm 112.
Means for biasing the arm 112 in opposition to the force applied to
the arm by virtue of the tension in the strip material, is also
provided. The biasing means may take any suitable form, so long as
the biasing force on the arm is substantially constant. A simple
way of accomplishing this is shown in FIGS. 8 and 9 and includes a
weight 122 on the end of a wire 124 looped about an idler pulley
126. The wire 124 is attached to the arm 112 by means of a pin 128
projecting from the end of the arm. A stop 129, mounted on the
frame 102, limits the outward movement of the arm 112.
The strip material leaving the roller 120 passes about a second
roller 130. The roller 130 is mounted upon a block 132 for free
rotation and is positionable along a rod 134 mounted spanning a
pair of spaced brackets 136 carried by the frame 102. Once chosen,
the position of the roller may be fixed with respect to the frame
by tightening a clamping screw 138, threadedly received by the
block 132, against the rod 134.
During operation of the strip material supply means 54, the
brakeshoe 116 is pressed against the periphery 106a to a greater or
lesser extent depending upon strip tension. If the tension of the
strip material increases, caused, for example, by greater unwinding
resistance in the supply roll, the arm 112 is drawn clockwise about
the pivot 110 against the biasing force of the weight 122, to
reduce the frictional drag force of the brakeshoe 116. The force
required to unwind the supply roll, and hence the tension of the
strip material, thereby decreases until equilibrium is reached once
again. On the other hand, should the strip material tension
decrease, the biasing force provided by the weight 122 tends to
overcome tension force to move the arm 112 counterclockwise and
press the shoe 116 against the periphery 106a with greater force,
thereby increasing the strip tension. When the device is in
equilibrium, a slight amount of frictional drag is applied to the
turntable periphery 106a and the tension and weight forces on the
arm are equal and opposite. It will be appreciated that the
frictional drag device is not as effective in coping with short
term or high frequency fluctuations in strip tension but is most
effective in regulating tension for long term or low frequency
variations while the rotating inertia of the turntable smooths out
the high frequency fluctuations.
The adhesive applying means 56 depicted in FIGS. 10 and 11,
impregnates the intermediate strip 28a with a liquid adhesive and
provides uniform, equal adhesive coatings on both faces of the
strip. The adhesive applying means 56 includes a platform 150
mounted on a suitable frame means (not shown). The platform 150 is
provided with an elongated rectangular opening 152 in its central
portion. An adhesive reservoir 154, in communication with the
opening 152, depends from the platform 150. Bordering the platform
on all sides is a fence 156 which prevents adhesive from spilling
over the edges of the platform 150. Mounted on the platform 150
within the enclosure defined by the fence 156 is a vertical support
member 158 carrying a spout assembly 159 which according to one
example, includes a horizontally projecting tube 160. The upper
half of the tube 160 is cut away along a portion of its length
forming a step 162. The interior wall of the tube 160 may be
provided with a plastic liner 164 to facilitate cleaning of the
tube. A cap 166, generally cylindrical in shape and provided with
central, horizontally oriented, oppositely disposed slits 168,
encloses the tube 160 during operation and completes the spout
assembly 159. The intermediate ply strip material 28a passes
through the slits 168 for exposure, on all sides, to the adhesive
supplied to the interior of the tube 160.
A conduit 170, which includes a pump 172, interconnects the bottom
of the adhesive reservoir 154 with a pipe 174 supported by the
member 158 and communicating with the interior of the tube 160.
Adhesive from the reservoir is thus circulated to the tube 160 and
any overflow passes down through the opening 152 back into the
reservoir 154. It will be noted that the plane of the strip 28a is
substantially parallel with the stream of adhesive within the spout
assembly, that is, the adhesive stream is directed against one of
the edges of the strip. This eliminates any tendency on the part of
the strip to bow or otherwise deflect within the spout as a result
of the force of the adhesive stream.
The viscosity of the adhesive must be such that it quickly
penetrates and completely wets the strip material 28a. As a result,
as little time as possible is lost in this process and a relatively
high strip velocity can be maintained. Swift & Company Adhesive
No. 2706, referenced above, is a high viscosity adhesive at room
temperature but is decidedly less viscous when heated. An adhesive
temperature of between 150.degree. and 160.degree. F. has been
found particularly satisfactory. At lower temperatures, the
adhesive is too viscous; at higher temperatures, chemical breakdown
of the adhesive begins. The reduced viscosity of the adhesive not
only assures complete, rapid saturation of the intermediate strip
material but makes the adhesive become tacky more quickly so that
the winding apparatus can be run at a higher speed. Complete
impregnation of the strip material by the adhesive assures that the
desired ultimate brittleness in the finished tube will be obtained.
Also, if the strip material, including the edges, is not completely
impregnated, an inferior finished product results. This shows up as
small flags of unadhered paper protruding forwardly from the
tapered forward end 20 of the exterior tube 14 after the tube has
been opened by the ejected tampon and destroys the smooth outer
surface of the tapered end of the tube. Further, if the strip
material is not tacky as it is wound about the mandrel, the inner
and outer strips 30a and 26a may slip with respect to the
intermediate strip 28a and this will upset the winding operation.
The belt 72 engages only the outer strip 26a and if the adhesive is
not sufficiently tacky, slippage will occur between it and the
other layers. Maintaining the adhesive at a low viscosity also
substantially reduces the force required to draw the intermediate
strip 28a through the doctor mechanism to be described later. This
is especially significant with respect to the intermediate strip
which is weak in the dry state and very weak when soaked.
Temperature control of the adhesive is accomplished by a heat
exchanger 176 surrounding the conduit 170 downstream of the pump
172. Hot water is circulated by a pump 182 through a closed circuit
178 into and out of the heat exchanger 176 from a supply tank and
heater unit 180. A temperature sensor 184, in contact with the
adhesive at a point near its entry into the tube 160, is connected
to a thermostat control system 186 which regulates the operation of
the heater in the unit 180. A temperature gauge 188, for observing
the adhesive temperature, is connected to the conduit 170 near the
temperature sensor 184. A bypass line 190, connected across the
series combination of the heat exchanger 176 and pump 172 is used
to regulate the flow of adhesive to the tube 160. For this purpose,
a first valve 192 is connected in the conduit 170 and a second
valve 194 is provided in the bypass line 190. By adjusting the
valves 190 and 192 the flow from the pump 172 can be split so that
the required amount of adhesive is supplied to the tube 160.
During operation of the apparatus described thus far, adhesive is
supplied to the spout 159 under pressure by the pump 172 so that
adhesive fills substantially the whole interior of the spout to
thoroughly wet both faces and both edges of the strip material 28a.
In one practical example, the pressure at the pump outlet is 40--50
p.s.i. The pressure drop between the pump outlet and the spout 159
is substantial; the pressure at the spout should be sufficient to
fill the spout interior and prevent formation of bubbles within the
spout which would result in dry spots on the strip 28a.
After leaving the tube 160, excess adhesive is removed from both
faces of the strip material 28a by a doctor mechanism 200. The
doctor mechanism 200 includes a lower, vertically oriented plate
assembly 202 having an upper, horizontally oriented, rounded edge
204 and an upper plate assembly 206 disposed coplanar with and
spaced apart from the lower plate assembly 202. The upper plate
assembly 206 has a lower, horizontal, rounded edge 208
substantially identical to the edge 204 of the lower plate assembly
and positioned parallel thereto. The rounded edges 204 and 208 are
preferably circular in cross section as shown in FIG. 11 and have a
radius of at least one-eighth inches. The lower and upper plate
assemblies 202 and 206 are similarly constructed, composite units.
Using the upper plate assembly 206 as an example, the lower
assembly 202 being substantially identical, a metal core 210 is
sandwiched between a pair of easily cleaned plastic sheets 212, the
three-layer structure being held together by suitable fasteners
214.
As best shown in the perspective of FIG. 10, the plate assembly 202
is carried between lateral blocks 216 and the plate assembly 206 is
similarly carried between blocks 218. A pair of vertical posts 219
secured to the platform 150 extend through vertical holes formed in
the blocks 216 and 218. The proper spacing between the rounded
edges of the plate means is furnished by spacers 220 interposed
between the blocks 216 and 218. The plate means 206 is biased
downwardly by a weight 222 having spaced-apart apertures for
receiving the posts 219. The weight 222 is necessary because the
adhesive which bunches up on the entry side of the doctor mechanism
200 tends to lift the upper plate assembly.
The rounded doctor surfaces assure a uniform coating, of equal
thickness, on both faces. If a relatively sharp-edged or knife
blade is used, as has been the practice in the past, the strip
material tends to ride against one or the other blade edge
resulting in almost complete removal of the adhesive from that
face. With rounded edges, a hydraulic wedge is formed on each face
of the strip material which tends to center the strip material as
it passes between the doctor surfaces.
Disassembly of the doctor mechanism 200 for cleaning is
accomplished simply by lifting the weight 222, the upper plate
assembly 206 and the lower plate assembly 202 off the posts.
By way of example, for strip material having a thickness of 0.006
inch, the spacing between the rounded edges 204 and 208 of the
plate assemblies, at their closest proximity, is maintained at
0.007 inch to form a layer of adhesive 0.0005 inch thick on each
face of the strip material. By the time the strip material 28a
reaches the mandrel, the adhesive is sufficiently tacky so that the
inner and outer strips 30a and 26a readily adhere. The thickness of
the adhesive layer is somewhat thinner than 0.0005 inch by the time
the strip reaches the mandrel because of evaporation; after
complete drying of the tube, the presence of the adhesive is not
discernible by measuring the thickness of the wall which is
approximately the total of the thicknesses of the individual plies.
The proper tackiness of the adhesive can be achieved by
experimentation. Some factors to observe and which will be readily
apparent to those skilled in the art, include the ambient
temperature and humidity, the winding speed and the distance
between the mandrel and the glue applying unit.
With respect to the distance between the exit of the spout assembly
159 and the entry to the doctor mechanism 200, a sufficient
separation must be provided so that the adhesive may soak into the
strip material completely before the doctor mechanism 200 is
reached. The separation distance must be increased with increasing
operating speeds. By way of example, with a strip speed of about 50
feet per minute, a separation distance of about 8 inches is
satisfactory.
As already stated, proper operation of the winding apparatus and
the quality of the ultimate product is affected by the thickness of
the adhesive applied to the faces of the intermediate strip 28a.
The requirement that the adhesive be tacky or partially set when
the strip 28a reaches the mandrel 62 dictates that a sufficient
distance separate the exit point of the doctor mechanism 200 from
the mandrel 62. For a strip velocity of 50 feet per minute, this
distance may be of the order of 4 feet. It has been found, however,
that in the version of the apparatus in which the strip is oriented
horizontally while passing through the spout 159, through the
doctor mechanism 200 and about the mandrel 62, there is a tendency
for the adhesive to accumulate to some extent on the lower surface
of the strip. This can result in occasional slippage between the
intermediate strip 28a and the inner strip 30a, the adhesive on the
lower surface of the strip 28a not having had the opportunity to
set to the necessary extent. On the other hand, the depleted layer
of adhesive on the upper surface of the strip 28a causes this layer
to set rather quickly and results in occasional dry spots where
there is little or no bonding between the intermediate and outer
strips. The result is a tube of inconsistent quality and an
excessive waste of of tube stock. This problem was eliminated by
providing the intermediate strip 28a with a 180.degree. twist as
indicated by the reference numeral 226 in FIG. 4, between the
doctor mechanism 200 and the mandrel 62. The twist is effective to
prevent accumulation of the adhesive by gravity on one surface at
the expense of the other since each surface faces upwardly for a
portion of its travel to the mandrel and downwardly during the
remaining portion.
With minor modifications, which will be readily apparent to those
skilled in the art, the spout assembly 159 and doctor mechanism 200
maybe oriented vertically. In this case, the strip 28a, which comes
off the supply roll vertically, passes through the spout assembly
and doctor mechanism without twisting and only a 90.degree. twist
is required between the doctor mechanism and the horizontal mandrel
62. Excess adhesive flows off the vertically oriented portion of
the strip leaving adhesive coatings of substantially equal and
uniform thickness on both faces of the strip.
Because of the frictional forces created between the fixed mandrel
62 and the rotating inner ply 30 of tube stock 92, it is necessary
to lubricate the mandrel surface in a continuous, controlled
fashion to permit the inner ply to slide over the mandrel surface
more easily. Without some form of lubrication, in view of the
tension on the strips and the force exerted by the belt 72 on the
tube stock being formed, there may be twisting and tearing of the
tube material. One way to reduce this problem has already been
discussed, namely, the provision of a reduced diameter portion on
the mandrel 62. However, some form of lubricating medium must be
applied to the inner strip to prevent tearing of the tube before it
reaches the reduced diameter portion. It has been found, in
accordance with one aspect of the present invention, that
lycopodium powder provides an excellent lubricating medium for the
winding of tubes used for hygienic media applicator devices. This
powder, however, is so finely divided that it flows like a low
viscosity liquid and difficulty is encountered in metering its
flow.
In accordance with another aspect of the present invention, shown
in FIGS. 12 and 13, a lycopodium powder dispensing device 230 is
provided. The dispenser 230 comprises a cylindrical container 232
for holding a supply 234 of lycopodium powder. The lower portion of
the container 232 is provided with a funnel section 236 terminating
at its lower end in an opening 238. Mounted below the funnel
section 236 is a cylindrical dispensing wheel 240 having a smooth
outer surface 241 in communication with the powder supply 234 via
the opening 238. The wheel 240 is securely mounted on a shaft 242
which is driven by an electric motor 244 to rotate the wheel 240 in
the direction of motion of the strip 30a. In operation of the
dispensing device, the motor 244 is set to rotate the wheel 240 at
a speed at which the proper amount of lubricating powder is picked
up by the wheel periphery 241 for a given strip speed. A plate 246
having guides 248 mounted on the top surface thereof supports and
guides the strip 30a past the outer periphery 241 of the wheel 240.
The wheel 240 turns within a cavity 250 formed within the funnel
section 236, the cavity being shaped to conform closely to the
shape of the wheel. A relatively high tolerance, uniform clearance
must be maintained between the wall of the cavity 250 and the outer
surfaces of the wheel 240, approximately 0.002 inches having been
found to provide satisfactory results.
The tube cutting means 60 forms no part of the present invention
and can take any suitable form. In the example shown in FIG. 4, a
cutting blade 260 is rotatably driven by a motor 262 secured to a
movable base 264. The movable base 264 is mounted for simultaneous
reciprocation in mutually orthogonal directions in timed relation
with the velocity of the formed tube stock 92 being discharged from
the mandrel 62. The base 264 is reciprocated (by means not shown)
longitudinally, that is, in a direction parallel to the mandrel 62,
along guide rods 266 mounted on a carriage 268. The carriage 268,
in turn, is mounted for lateral reciprocation, that is, in a
direction perpendicular to the mandrel axis, along guide rods 270
carried by a fixed base 272. Movement of the carriage 268 is
provided by hydraulic cylinder/piston means 274 having a piston rod
276 extending therefrom and connected to the carriage 268. The
cutting operation is performed when the carriage 268 is drawn
laterally to move the cutting blade 260 across the path of the tube
stock being discharged from the mandrel 62, while simultaneously
being moved longitudinally at the velocity of the discharging tube
stock so that a straight cut results. Other types of tube cutters,
including gang cutters capable of severing a plurality of tube
lengths simultaneously, will suggest themselves to those skilled in
the art.
Although particular hygienic applicator devices and particular
methods and apparatus have been described to illustrate various
manners in which such devices can be fabricated and utilized in
accordance with the present invention, it will be appreciated that
the present invention is not limited to such particular
illustrations and descriptions. Accordingly, any and all
modifications, alterations and equivalent arrangements for such
devices and the methods and apparatus for fabricating the same
falling within the scope of the following claims should be
considered to be part of the present invention.
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