U.S. patent application number 10/634398 was filed with the patent office on 2004-02-12 for method and apparatus for making bristle subassemblies.
Invention is credited to Edwards, Mark Stephen, Staunton, Harold Francis.
Application Number | 20040026042 10/634398 |
Document ID | / |
Family ID | 31496145 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040026042 |
Kind Code |
A1 |
Edwards, Mark Stephen ; et
al. |
February 12, 2004 |
Method and apparatus for making bristle subassemblies
Abstract
An apparatus for continuously making a bristle subassembly
comprising: (a) a mandrel having at least three sides and having a
moving cable support on each corner running a substantial length of
the mandrel on the exterior corner of the mandrel; (b) a wrapping
means for continuously wrapping a polymeric filament around the
axis of the mandrel to form a wrap of polymeric filaments; where
the wrap of polymeric filaments is being supported and moved along
a substantial length of the mandrel by the moving cable support;
(c) a means for feeding at least one base string outside of the
wrap of polymeric filaments to a selected portion of the mandrel as
required to form the subassembly while the wrap of polymeric
filaments is being moved at least a portion of the length of the
mandrel by the cable support of the mandrel; (d) a means for
continuously bonding the base string and polymeric filaments of the
wrap together by simultaneously pressing the base string in contact
with the polymeric filaments of the wrap and applying energy to the
base string and the polymeric filaments of the wrap; and (e) a
cutting means for cutting the wrap of polymeric filaments at a
point downstream of where the polymeric filaments of the wrap are
bonded with the base string to form at least one bristle
subassembly having at least one row of filament segments connected
to at least one base string.
Inventors: |
Edwards, Mark Stephen;
(Hockessin, DE) ; Staunton, Harold Francis;
(Avondale, PA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
31496145 |
Appl. No.: |
10/634398 |
Filed: |
August 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10634398 |
Aug 5, 2003 |
|
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09550657 |
Apr 17, 2000 |
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6638384 |
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Current U.S.
Class: |
156/428 ;
156/435 |
Current CPC
Class: |
D04D 3/00 20130101; D04D
11/00 20130101; A46B 5/06 20130101 |
Class at
Publication: |
156/428 ;
156/435 |
International
Class: |
B65H 081/00 |
Claims
1. An apparatus for continuously making a bristle subassembly
comprising: (a) a mandrel having at least three sides and having a
moving cable support on each corner running a substantial length of
the mandrel on the exterior corner of the mandrel; (b) a wrapping
means for continuously wrapping a polymeric filament around the
axis of the mandrel to form a wrap of polymeric filaments; where
the wrap of polymeric filaments is being supported and moved along
a substantial length of the mandrel by the moving cable support;
(c) a means for feeding at least one base string outside of the
wrap of polymeric filaments to a selected portion of the mandrel as
required to form the subassembly while the wrap of polymeric
filaments is being moved at least a portion of the length of the
mandrel by the cable support of the mandrel; (d) a means for
continuously bonding the base string and polymeric filaments of the
wrap together by simultaneously pressing the base string in contact
with the polymeric filaments of the wrap and applying energy to the
base string and the polymeric filaments of the wrap; and (e) a
cutting means for cutting the wrap of polymeric filaments at a
point downstream of where the polymeric filaments of the wrap are
bonded with the base string to form at least one bristle
subassembly having at least one row of filament segments connected
to at least one base string.
2. The apparatus of claim 1 wherein the means for bonding the base
string and the polymeric filaments of the wrap together is a wave
energy source that applies sufficient wave energy to partially melt
at least one of the base string and the polymeric filaments of the
wrap.
3. The apparatus of claim 2 wherein the wave energy source is an
ultrasonic horn operated at 20-70 kHz and positioned adjacent to
the mandrel and defines an opening sufficient to allow passage of
the base string and the polymeric filaments of the wrap and
maintains the base string in contract with the filaments of the
wrap and does not allow the base string to reposition itself.
4. The apparatus of claim 1 wherein the wrapping means continuously
forms the wrap by using at least one polymeric filament under
controlled tension and the wrapping means rotates at controlled
rates around the axis of the mandrel to form the wrap of polymeric
filaments that is first brought into contact with a cable which is
an endless cable and then with the base string.
5. The apparatus of claim 4 wherein at least one base string is
positioned on at least one corner of a four sided mandrel outside
of the wrap of polymeric filaments and each endless cable support
runs along one corner along the length of the mandrel protruding
outward from the intersection of the two side planes of the mandrel
which form the corner of the mandrel and runs in an opposite
direction in a recessed channel in the mandrel located on a
diagonal side of the mandrel from said corner and does not protrude
into the plane of the mandrel side.
6. The apparatus of claim 4 wherein at least one base string is
positioned on at least one side of a four sided mandrel outside of
the wrap of polymeric filaments and each endless cable support runs
along one corner along the length of the mandrel protruding outward
from the intersection of the two side planes of the mandrel which
form the corner of the mandrel and runs in an opposite direction in
a recessed channel in the mandrel located on a diagonal side of the
mandrel from said corner and does not protrude into the plane of
the mandrel side.
7. The apparatus of claim 1 wherein the means for bonding the base
string and the polymeric filaments of the wrap together includes
solvent bonding means.
8. The apparatus of claim 1 where the means for bonding the base
string and the polymeric filaments of the wrap together is an
adhesive bonding means.
9. The apparatus of claim 1 where a thermoplastic polymer is
applied to the surface of the filaments of the wrap forming a
connecting and supporting structure with the filaments of the
wrap.
10. An apparatus for making bristle subassemblies, comprising: (a)
a mandrel having at least three sides and having a moving cable
support on each corner running the length of the mandrel on the
exterior corner of the mandrel; (b) wrapping means for continuously
wrapping a polymeric filament around the axis of the mandrel to
form a plurality of polymeric filament wraps, adjacent ones being
in contact with each other, wherein the wraps are supported and
moved along a substantial length of the mandrel by the moving cable
support; (c) bonding means for continuously bonding the polymeric
filament wraps together by applying energy to the polymeric
filament wraps; and (d) cutting means for cutting the wraps of
polymeric filaments at a point downstream of where the polymeric
filament wraps are bonded to form at least one bristle subassembly
having at least one row of filament segments connected to each
other along a bond line formed by applying energy.
11. An apparatus according to claim 10, wherein the bonding means
is selected from the group consisting of heating means, adhesive
means, and solvent means.
12. An apparatus for making a bristle subassembly comprising: (a)
means for continuously forming a wrap of polymeric filaments and
including means for wrapping at least one filament around the axis
of a four sided mandrel having a moving endless cable support on
each corner, said endless cable support runs along one corner along
at least a portion of the length of the mandrel protruding outward
from the intersection of the two side planes of the mandrel which
form the corner of the mandrel and runs in an opposite direction in
a recessed channel in the mandrel located on a diagonal side of the
mandrel from said corner and does not protrude into the plane of
the mandrel side and moves the wrap of polymeric filaments along a
substantial length of the mandrel; (b) means for feeding pairs of
base strings of a polymeric monofilament outside of the wrap of
polymeric filaments on each side of the mandrel while the wraps are
being moved substantially the length of the mandrel; (c) means for
bonding the base strings and the polymeric filaments of the wrap
together by simultaneously pressing the base string in contact with
the polymeric filaments of the wrap and applying energy to the base
strings and the polymeric filaments of the wrap; and (d) means for
cutting the wrap at a point downstream of where the polymeric
filaments of the wrap are bonded with the base strings to form
bristle subassemblies each having at least one row of filament
segments connected between two base strings; and wherein the means
for bonding of the base strings and the polymeric filaments of the
wrap together includes means for moving the base strings and the
filaments of the wrap under a wave energy source which is an
ultrasonic horn positioned adjacent to the mandrel that defines an
opening sufficient to allow passage of the base strings and the
filaments of the wrap and maintains the base strings in contract
with the filaments of the wrap and does not allow the base strings
to reposition itself and sufficient wave energy is applied at a
frequency of 20-70 kHz to partially melt at least one of the base
strings and the filaments of the wrap.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/130,883, filed Apr. 23, 1999.
FIELD OF THE INVENTION
[0002] This invention relates to a method and apparatus for making
polymeric bristle subassemblies having a base string with polymeric
filament bristles attached thereto and also to polymeric bristle
subassemblies wherein the polymeric filament bristles are attached
to each other without the presence of a base string.
BACKGROUND OF THE INVENTION
[0003] Various methods for making elongated pile articles having a
support strand or base string with a plurality of yarn bundles
attached thereto that are useful in making carpet are shown in
Mokhtar et al U.S. Pat. No. 5,470,629 issued Nov. 28, 1995, Edwards
et al U.S. Pat. No. 5,547,732 issued Aug. 20, 1996, Mokhtar et al
U.S. Pat. No. 5,498,459 issued Mar. 12, 1996, Edwards et al U.S.
Pat. No. 5,472,762 issued Dec. 5, 1995 and Agreen et al WO 97/06003
published Feb. 20, 1997. These processes require a base string or
support strand of a polymeric filament to move the wrap of yarn or
filament along a mandrel as it is being processed to form the
article. In a preferred ultrasonic bonding method for assembling
these articles, one limitation of the method is that the bonding
device must deliver vibrational energy through the wrap of yarns or
filaments to the contact interfaces with the support strand to
generate heating and partial melting of the strand and/or wrap.
However, since the mass cross-sections of the yarns or filaments of
the wrap are commonly smaller than the support strand
cross-section, the bonding energy delivered to the interface of the
wrap and the support strand must be controlled precisely within a
given bonding window to produce surface melting at the interface of
the wrap and the support strand while avoiding sufficient bulk
heating in the wrap of yarns or filaments to damage or sever them.
A wrap of small diameter yarns or filaments may exhibit narrow or
even a nonexistent bonding window that results in an unstable or
unsatisfactory process. Another limitation of these processes is
that the support strand must maintain sufficient strength during
the partial melting in the bonding step to transport the article
through the process. The support strand must have a large enough
cross-section or have a sheath/core structure with a core of a
significantly higher melting material that it will not break under
the tension and melting which occur during the process.
[0004] A process and apparatus are needed in which the requirements
of the support strand or base string are reduced allowing for the
use of a variety of sizes and types of base strings to form bristle
subassemblies.
SUMMARY OF THE INVENTION
[0005] A continuous method for making a polymeric bristle
subassembly using the steps of
[0006] (1) continuously forming a wrap of polymeric filaments by
wrapping at least one filament around the axis of at least a three
sided mandrel having a moving cable support on each corner running
the length of the mandrel on the exterior corner of the mandrel
capable of supporting and moving the polymeric filaments of the
wrap along at least a portion of the length of the mandrel;
[0007] (2) feeding at least one base string outside of the wrap of
polymeric filaments to a selected portion of the mandrel as
required to form the subassembly, such as the corner or side of the
mandrel, while the polymeric filaments of the wrap are being moved
along at least a portion of the length of the mandrel;
[0008] (3) bonding the base string and the polymeric filaments of
the wrap together by simultaneously pressing the base string in
contact with the filaments of the wrap and applying energy to the
base string and the polymeric filaments of the wrap; and
[0009] (4) cutting the polymeric filaments of the wrap at a point
downstream of where the polymeric filaments of the wrap are bonded
with the base string to form at least one bristle subassembly
having at least one row of filament segments connected to at least
one base string.
[0010] An apparatus for making the subassemblies is also part of
this invention. Other aspects of this invention are a continuous
method of making a bristle subassembly wherein the base string is
omitted and the filaments of the wrap are bonded to each other
through the use of an energy source, or the use of a polymeric bead
to bond the filaments together or use of a solvent or an adhesive
to bond the polymeric filaments of the wrap together to form a
bristle subassembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic showing the method for forming a
typical bristle subassembly.
[0012] FIG. 2 is an elevation view of equipment for forming a
typical bristle subassembly.
[0013] FIG. 3 is a diagram of the path of travel of one endless
cable support.
[0014] FIG. 4 is a detail of the mandrel.
[0015] FIG. 5 is a mandrel detail at horizontal section 5-5.
[0016] FIG. 6 is a side view of ultrasonic horn
[0017] FIG. 7 is a front view of ultrasonic horn
[0018] FIG. 8 is a cross section of ultrasonic horn holding base
string in contact with wrap.
[0019] FIG. 9 is a perspective view of a typical bristle
subassembly formed by the method of the invention.
[0020] FIG. 10 is a cross-section of a two base string bristle
subassembly made by using a four sided mandrel and cut on two
opposing sides of the mandrel.
[0021] FIG. 11 is a cross-section of another two base string
bristle subassembly that uses adjacent pairs of base strings and is
cut between the paired base strings using the process as shown in
FIG. 12.
[0022] FIG. 12 is a schematic of the method using paired base
strings.
DETAILED DESCRIPTION OF THE INVENTION
[0023] This invention is directed to a continuous process for
making bristle subassemblies by forming a wrap of polymeric
filaments around a mandrel having at least three sides and
preferably four sides. There is at least one moving cable support
that moves the wrap of polymeric filaments along a substantial
length of the mandrel; preferably one endless cable support is
positioned on each corner of the mandrel. In the preferred
embodiment of this invention, the endless cable support moves away
from the wrapper mechanism, is positioned on each of the exterior
corners of the mandrel and runs along the corner and returns by
running down a recessed channel in a diagonal opposing face of the
mandrel in the opposite direction. For a single base string bristle
subassembly, at least one base string is fed outside of the wrap of
polymeric filaments on either a side of the mandrel or on a corner
of the mandrel. For alternative bristle subassemblies, there can be
at least one base string positioned on at least one side of the
mandrel. The number and position of the base string(s) depends on
the type of bristle subassembly that is to be made. At the point
just prior to the base string being bonded with the polymeric
filaments of the wrap on the mandrel, the base string is maintained
in direct contact with the filaments of the wrap while the
filaments of the wrap are being moved along the length of the
mandrel and the base string is bonded to the filaments of the wrap
by applying energy to the base string, usually ultrasonic energy,
to at least partially melt the base string and/or the filaments of
the wrap. In one embodiment of this invention, the filaments of the
wrap are then cut at a point down stream of where the base string
is bonded to form a plurality of bristle subassemblies having two
rows of filament segments connected to the base string. Other
subassemblies can be made by the process of this invention as will
be described hereinafter.
[0024] The filament used as the base string has a diameter of
50-5,000 microns and the filament used for the wrap has a diameter
of 12-5,000 microns.
[0025] The base string may be a bundle of filaments wherein at
least one filament of the bundle is a monofilament of a
thermoplastic polymer and the remaining filaments can be of natural
fibers such as cotton, jute, hemp and the like, or man made
non-thermoplastic filaments, such fiberglass. Alternatively, the
base string may be a bundle of natural fibers or non-thermoplastic
filaments. Where the base strings are comprised of natural fibers
or non-thermoplastic filaments, the filaments of the wrap must be
made of a thermoplastic polymer for a bond to occur using thermal
energy. The requirement for the filaments of the wrap to be of a
thermoplastic polymer is eliminated when the means of bonding is an
adhesive or application of a thermoplastic bead.
[0026] The base string and the polymeric filaments of the wrap
usually are monofilaments of thermoplastic polymers. Typically
useful thermoplastic polymers are aliphatic polyamides, aromatic
polyamides, polyesters, polyolefins, polystyrenes, styrene
copolymers, polyvinylchloride, fluoropolymers, polyurethanes or
polyvinylidene chloride. Co-extrusions of the above polymers can be
used to enhance the properties of the bristle subassembly by
combining the individual properties of each of the polymers.
[0027] Polyamides, such as nylon 4, nylon 6, nylon 11, nylon 12,
nylon 6,6, nylon 6,12, nylon 6,14, nylon 10,10 and nylon 12, 12,
are preferred for bristles used in brushes. For toothbrush bristle
applications, nylon 6,12 (polyhexamethylene dodecane amide) is
preferred since it has superior properties of flexibility, bend
recovery and wear resistance.
[0028] Polyesters which have been found useful for bristle include
polybutylene terephthalate and polyethylene terephthalate, of which
the first is particularly preferred. Of the many polyolefins which
can be used for bristle manufacture, polypropylene is better
suited.
[0029] Typically, these monofilaments used for the wrap contain
additives such as abrasives, colorants, light reflecting particles
such as aluminum flake and cellophane, therapeutic agents,
anti-microbial agents and mixtures thereof in amounts of 0-50% by
weight, preferably 0.1-40% by weight, based on the weight of the
monofilament. Typically useful abrasive particles are as follows:
aluminum silicate, silicon carbide, aluminum oxide, alumina
zirconia, silicon dioxide, sodium aluminum silicate, cubic boron
nitride, garnet, pumice, emery, mica, quartz, diamond, boron
carbide, fused alumina, sintered alumina, walnut shells and any
mixtures thereof.
[0030] Flake particles can be added to the monofilament used for
the wrap in amounts of 0.2-5.0% by weight, based on the weight of
the monfilament. Preferred flake particles are flakes of aluminum
and cellophane. Aluminum has excellent light reflecting properties,
which improves its visibility in the filaments. It is inexpensive,
widely available in film and flake form and is safe to use.
Aluminum flake that is approved for food contact is preferred for
use in toothbrushes. Aluminum and cellophane are not melted or
destroyed in the processing steps used to form the filaments.
Preferably, these flakes are formed by die cutting aluminum foil or
cellophane sheets.
[0031] An apparatus for continuously making a bristle subassembly
is also part of this invention. The apparatus comprises the
following:
[0032] (1) a mandrel having at least three sides and having a
moving cable support on each corner running at least a portion of
the length of the mandrel on the exterior corners of the
mandrel;
[0033] (2) a wrapping means for continuously wrapping a polymeric
filament around the axis of the mandrel to form a wrap of
filaments; where the wraps are supported and moved along at least a
portion of the length of the mandrel by the cable support;
[0034] (3) a means for feeding at least one base string outside of
the wrap of filaments to a selected portion of the mandrel as
required to form the selected bristle subassembly while the wrap of
polymeric filaments is being moved along at least a portion of the
length of the mandrel by the cable support;
[0035] (4) a means for continuously bonding the base string and the
polymeric filaments of the wrap together by simultaneously pressing
the base string in contact with the filaments of the wrap and
applying energy to the base string and the filament of the wrap;
and
[0036] (5) a means for cutting the wrap of polymeric filaments at a
point downstream of where filaments of the wrap are bonded with the
base string to form at least one bristle subassembly having at
least one row of filament segments connected to at least one base
string.
[0037] Preferably, the means for bonding the base string and
polymeric filaments of the wrap together is a wave energy source
from an ultrasonic horn that applies sufficient wave energy to
partially melt at least one of the base string, the polymeric
filaments of the wrap or both. The ultrasonic horn is positioned
adjacent to the mandrel and defines an opening sufficient to allow
passage of the base string and wrap of filaments and maintains the
base string in contract with the wrap of filaments and does not
allow the base string to reposition itself.
[0038] The following are preferred embodiments of the
apparatus:
[0039] Endless cables are used to convey the wrap of filaments
while being processed on the mandrel. The movement of each cable is
synchronized to achieve the preferred normal angle between the wrap
of filaments and the base string. The preferred cable construction
is of 7.times.7 wire rope of diameters, {fraction (1/32)},
{fraction (3/64)} or {fraction (1/16)} inch. The 7.times.7 wire
rope is easily spliced to form an endless cable with a uniform
diameter and most importantly without surface variations which
could cause a repeating defect in the bristle subassembly.
Additionally, the 7.times.7 construction has good flexibility
allowing the use of small diameter pulleys at the bottom of the
mandrel without a significant adverse effect on cable life. Other
suitable materials for endless cables are large caliber
monofilaments such as those used for Lawn and Garden string
trimmers; and braided Kevlar.RTM. cord.
[0040] The wrapping means continuously forms a wrap by using at
least one filament under controlled tension and rotates around the
axis of the mandrel to form the wrap of filaments that are first
brought into contact with an endless cable and then with the base
string.
[0041] A base string is positioned on each corner of a four sided
mandrel outside of the wrap of filaments and the endless cable
support runs along one corner along the length of the mandrel
protruding outward from the intersection of two side planes that
form the corner of the mandrel and runs in an opposite direction in
a recessed channel in the mandrel located on a diagonal side of the
mandrel from the corner so as not to protrude into the plane of the
mandrel side.
[0042] Alternatively, at least one, and preferably two base strings
are positioned on each side of a four sided mandrel outside of the
wrap of filaments and the endless cable support runs along each
corner along the length of the mandrel and runs in an opposite
direction in a recessed channel in the mandrel located on a
diagonal side of the mandrel from said corner.
[0043] Following is a detailed description of FIGS. 1-12 to show
the method, apparatus and resulting products of this invention:
[0044] FIG. 1 shows a schematic of a preferred embodiment of the
process of this invention. Filament 1 is fed from a spool (not
shown) through a tensioning drive (not shown) and is continuously
wrapped around the four-sided mandrel 5 by a wrapping mechanism 2
to form a continuous wrap 6 on the mandrel 5. A high speed wrapping
mechanism is used which is an improvement to the conventional
wrapping mechanism U.S. Pat. No. 5,547,732, which is hereby
incorporated by reference.
[0045] A cable, preferably an endless cable support 4 which can be
a metal wire or a suitable polymeric cable runs down along groove
7a on the face of the mandrel and its direction is reversed by
pulley 3a and the cable then runs up the corner 7b of the mandrel
and moves the wrap 6 along the length of the mandrel 5. Cable 4 is
redirected and runs down the back of the mandrel 5 in groove 7c and
is redirected again by pulley 3b and runs up in the corner 7d of
the mandrel and supports the wrap and moves the wrap along the
length of the mandrel 5. Endless support cable 4a (not shown) is
synchronized with cable 4 and is positioned similarly on the two
remaining opposite corners of the mandrel and run in grooves on the
opposite side of the mandrel. Pulleys (not shown) are required for
the second endless cable to redirect and reverse the direction of
the endless cable 4a.
[0046] Base strings 8a, 8b, 8c, and 8d are fed through
corresponding guide tubes 13a, 13b, 13c, and 13d to each side of
the mandrel 5, preferably to each corner of the mandrel 5 as shown
in FIG. 1, and brought into contact with the wrap 6. Ultrasonic
assemblies 9a, 9b, 9c, and 9d hold the base strings 8a-d in contact
with the wrap 6 and provide sufficient energy to at least partially
melt the base strings, the filaments of the wrap or both the base
strings and the wrap and bond both together. Typically, 0.1-5.0
joule energy is used to bond a thermoplastic polyamide monofilament
base string to the filaments of the wrap.
[0047] As the filaments of the wrap are bonded with the base string
and proceed along the length of the mandrel 5, the filaments of the
wrap are cut by cutters 10a and 10b into a plurality of bristle
subassemblies 11a, 11b, 11c and 11d. Not shown are cutters on the
opposite sides of the mandrel positioned opposite cutters 10a and
10b. The bristle subassemblies 11a-d are then wound on spools and
are available for use in making articles such as brushes,
particularly toothbrushes.
[0048] FIG. 4 shows a groove 22 commonly referred to as a bed knife
to assist the blade of the cutter. Each of the cutters is a
rotating cutting blade and each blade intersects the bed knife in
the side of the mandrel with about a 0.25 mm clearance on each side
of the blade. The blades may be 0.8-1.6 mm thick with a sharp edge
at the perimeter having an included angle of 20-45.degree. and are
made from a variety of materials such as ittria stabilized zirconia
available from Ceramco, Inc., Center Conway, N.H.
[0049] FIG. 2 is an elevation view of the equipment used to
manufacture the bristle subassembly. The mandrel 5 is positioned so
that the longitudinal centerline of the mandrel 5 is aligned with
the centerline axis of the wrapper mechanism 2. Base strings 8a and
8b are fed through guide tubes 13a, 13b which are held in place by
supports 23a, 23b, 23c, and 23d. Only two base strings 8a and 8b
and the corresponding guide tubes are shown. The guide tubes are
bent at the discharge end to gently transition the base strings
from a horizontal to a vertical orientation. The angle between the
mandrel and the base string leaving the guide tube is no more than
45.degree. and preferably less than 30.degree. to improve tracking
of the base string into the interface of the ultrasonic horn and
filament of the wrap.
[0050] The base strings 8a and 8b are drawn between the face of the
ultrasonic horns 16a and 16b and the corner cables wrapped with the
wrap 6 of polymeric filaments. Energy is transferred from the
ultrasonic assemblies 9a and 9b, to the base strings 8a and 8b and
the filaments of the wrap 6 by pressing the frontal contact surface
of the vibrating horn tip against the base string as it and the
filaments of the wrap are being transported past the vibrating horn
tip.
[0051] Each ultrasonic assembly 9a and 9b is comprised of three
major components. The ultrasonic transducers 14a and 14b convert
electrical energy into longitudinal-mode mechanical energy
(motion). Ultrasonic boosters 15a and 15b are mechanical amplifiers
that either increase or decrease the amplitude of the
longitudinal-mode vibrations. Properly configured horns 16a and 16b
transfer the vibrational energy to the filaments as they pass by
the horns. Ultrasonic assemblies 9a and 9b are held in place by
supports 23a-d. A force is regulated to each horn assembly by
pneumatic air cylinders (not shown) which creates a compression
force (typically 2.2-22.0 kg) on the base string and the filaments
of the wrap passing between the horn and mandrel.
[0052] Cutter assemblies 18a and 18b are mounted on movable bases
19a and 19b respectively, and cutters 10a and 10b slit the wrap
bonded to the base string to form bristle subassemblies 11a and
11b. The bristle subassemblies 11a and 11b are passed over
corresponding rollers 26a and 26b and then wound onto spools, not
shown. The rollers are non-driven rotating cylinders that change
the direction of the bristle subassembly from the vertical to the
horizontal or to some other angle. Only two cylindrical rollers are
required for the four bristle subassemblies and are positioned
parallel to and with adequate spacing from the mandrel so that the
vertical centerline of the approaching bristle subassembly is
maintained parallel to the mandrel and against the endless cable
traveling up the mandrel.
[0053] FIG. 3 is a detailed diagram of the path of travel for one
of the two endless cable supports. The endless cable support 4 is
driven by a motorized pulley 20 and travels through a tensioning
system of fixed pulleys 3d and 3f and a moveable pulley 3e which
adjust automatically to maintain the set tension on the cable
support 4. Cable 4 travels over pulley 3g which changes direction
of the cable and aligns it in a groove 7c on the face of the
mandrel 5. Pulley 3b reverses the direction of the cable 4 and
maintains the alignment with grove 7b in the corner of the mandrel
5. Pulley 3i reverses direction of the cable and aligns the cable
to travel in grooves 7a and 7b of the mandrel 5. Pulley 3a reverses
the direction of the cable and aligns the cable to travel in the
corner grove 7d of the mandrel 5 and then over alignment pulleys 3j
and 3k back to the motorized pulley 20. A similar endless cable
support, pulley system, path of travel and drive pulley (not shown)
are used for a second endless support cable that runs in the
opposite corners of the mandrel not covered by above cable 4. Both
endless cables are synchronized to travel at identical rates and
can be speed adjusted for various production rates. The population
density of bristles of a bristle subassembly is set by controlling
the wrapping mechanism rotational speed relative to the linear
speed of the endless cables.
[0054] FIG. 4 shows the mandrel 5 detail in which the axis of
pulleys 3a and 3b are offset from the axis of pulleys 3c and 3d (3d
not shown) to prevent interference between the pulleys that carry
the support cables. Groove 22 for the cutter is shown. The grooves
in the corners of the mandrel are subject to wear and each corner
has a replaceable corner plate 24. The corner plate is held in
place by screws and can be replaced when worn excessively.
[0055] FIG. 5 shows the mandrel detail horizontal section 5-5 which
shows the recessed grooves 7a and 7c each on an opposite face of
the mandrel 5 and the corner grooves 7b and 7d of the mandrel.
Unmarked are the opposing corners and recessed grooves on the
mandrel.
[0056] FIG. 6 shows a side view of the ultrasonic horn 16 and shows
the radius 21a which facilitates a smooth transition of the base
string and the wrap under the ultrasonic horn. The horn is operated
at a frequency of 20-70 kHz and preferably at 50 kHz. The vibration
amplitude of the horn tip is in the range of 25-75 microns.
[0057] FIG. 7 shows a front view of the ultrasonic horn 16 having a
V shaped recess and a semicircular channel 21b at the apex of the V
that is designed to self correct migration of a circular base
string. As more clearly shown in FIG. 8, the spatial gap-a-between
the filaments of the wrap 6 and each side leg of the horn V is less
than the diameter-b-of the base string 8.
[0058] FIG. 8 shows a cross-section of the ultrasonic horn holding
the base string 8 in contact with the filaments of wrap 6. The
endless support cable 4 runs in the groove along the corner of the
mandrel 5, the filaments of wrap 6 are carried by the cable 4 and
the base string 8 is held in position by the recessed semicircular
channel 21b of the V in the horn 16. The distance-b-which
approximates the diameter of the base string is greater than the
distance-a-between the side of the V in the horn and the filament
of the wrap 6. This design prevents the migration of the base
string 8 out of the semicircular channel 21b of the horn and keeps
the base string in contact with the filament of the wrap during
ultrasonic bonding of the base string and the filaments. FIG. 8
also illustrates the additional benefit of carrying the filaments
of the wrap 6 on the cable 4 in that the cable provides a thermal
sink for the wrap during bonding. The filaments of the wrap are
protected from excessive heating and melting during the bonding
step with the base string since the cable, particularly a metal
cable, acts as a thermal sink to dissipate energy which would
otherwise accumulate in the filaments of the wrap and thereby
protects the integrity of the filaments of the wrap.
[0059] FIG. 9 shows one of the many alternative bristle
subassemblies after it has been made by the method of this
invention. The base string 8 is bonded to the filaments of the wrap
6 which have been cut to form the bristles of the subassembly.
[0060] FIG. 10 shows a cross-section of a bristle subassembly
having two base strings that can be made via the method shown in
FIG. 1 except only two cutters are used on opposing sides of the
mandrel
[0061] FIG. 11 shows a cross-section of a bristle subassembly
having two base strings on each side made via the method shown in
FIG. 12.
[0062] In FIG. 12, the filaments of the wrap 6 are transported
along the mandrel 5 by an endless support cable as shown in FIG. 1
Base strings 8a and 8a are fed through guide tube 28a to
predetermined positions on the face of the mandrel 5 as are base
strings 8b and 8b through guide tube 28b. The base strings 8a and
8b are shown just left of the center of each mandrel face, while
base strings 8a and 8b are slightly to the right of the mandrel
face center. The spacing between paired base strings, such as base
strings 8a and 8a is slightly more than the width of the cutter
blade 10a. The base strings are passed under ultrasonic horn
assemblies 27a and 27b each having a horn face with two properly
spaced and sized semicircular channels for positioning each of the
circular base strings and keeping them in contact with the
filaments of the wrap. These base strings are ultrasonically bonded
to the filaments of the wrap. Cutters 10a and 10b are positioned on
the mandrel to cut the filaments of the wrap between each of the
base strings to provide a bristle subassembly shown in FIG. 11.
Cutters on the opposite sides of the mandrel (not shown) also cut
the bonded filaments to provide four bristle subassemblies.
[0063] There are several alternative methods for making bristle
subassemblies. Referring to FIG. 1, the base strings are omitted
but care is taken when forming the wrap to provide a sufficient
filament density so that the filaments of the wrap are tightly
packed next to each other. The filaments of the wrap are bonded by
the ultrasonic horn at the corner to form a bristle subassembly as
shown in FIG. 9 except the base string 8 is not present.
[0064] In another alternative method, again referring to FIG. 1,
the base string and the ultrasonic assembly are replaced by a
polymeric bead which is extruded onto the wrap of filaments and
bonds the filaments of the wrap to the polymeric bead. A bristle
subassembly similar to the one shown in FIG. 9 will be formed
except a polymer bead replaces the base string 8.
[0065] In still another alternative method, again referring to FIG.
1, the ultrasonic assembly is omitted and a solvent or an adhesive
for the filaments is dispensed onto the wrap of filaments which
bonds the filaments to the base string. A bristle subassembly
similar to the one shown in FIG. 9 will be formed.
[0066] In still another alternative method, again referring to FIG.
1, the base string and the ultrasonic assembly are omitted and a
solvent or an adhesive for the filaments is dispensed onto the wrap
of filaments which bonds the filaments together. A bristle
subassembly similar to the one shown in FIG. 9 will be formed
except the base string 8 will not be present
[0067] According to another aspect of the present invention, the
apparatus and methodology described herein can be used with yarns,
consisting of multiple micro-filaments, used as the wrap. Thus, a
continuous supply of yarn or yarn-like material is wrapped around
the mandrel in the same manner described above with respect to the
monofilament wrap and bonded to the base string such as those
described above. The function of the base string, which in prior
devices helped to transport the monofilament wraps to the bonding
stations, is not necessary when using the apparatus described
herein.
[0068] The methodology for making tuft-strings from endless strands
of yarn is similar to that used to make bristle subassemblies as
described above. In particular, a continuous method for making a
yarn tuft string includes the steps of
[0069] (1) continuously forming a wrap of yarn by wrapping at least
one yarn around the axis of at least a three sided mandrel having a
moving cable support on each corner running substantially the
length of the mandrel on the exterior corner of the mandrel capable
of supporting and moving the yarn wrap along a substantial length
of the mandrel;
[0070] (2) feeding at least one base string outside of the wrap of
yarn to a selected portion of the mandrel as required to form the
tuft string, such as the corner or side of the mandrel, while the
wrap of yarn is being moved substantially the length of the
mandrel;
[0071] (3) bonding the base string and the wrap of yarn together by
simultaneously pressing the base string in contact with the wrap of
yarn such that the yarn bundle is compressed and applying energy to
the base string and the wrap of yarn; and
[0072] (4) cutting the wrap of yarn at a point downstream of where
the yarn is bonded with the base string to form at least one tuft
string having at least one row of tufts connected to at least one
base string.
[0073] The tuft-strings thus made can be used to make any of a
variety of products, including carpeting and other floor
coverings.
[0074] The yarn materials can be any of the known varieties in
which hundred of individual filaments can be found in the
cross-section of a single strand. The physical properties of the
yarn materials are different from the aforementioned monofilament
materials. Common examples of the yarn materials can be found in
residential and commercial carpeting, while the monofilament
material is used to make brush bristles, fishing line, racquet
strings, etc. The manufacturing parameters of the machinery,
including the feed rate of the continuous strand of material that
comprises the "wraps" can be customized to match the material.
* * * * *