U.S. patent application number 10/358900 was filed with the patent office on 2003-06-26 for bristles having varying stiffness.
Invention is credited to Edwards, Mark Stephen.
Application Number | 20030115703 10/358900 |
Document ID | / |
Family ID | 24301828 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030115703 |
Kind Code |
A1 |
Edwards, Mark Stephen |
June 26, 2003 |
Bristles having varying stiffness
Abstract
Bristle stiffness is varied by allowing a support beam that
carries the bristles to undergo torsional movement in response to
brushing action. Torsional movement is achieved by allowing the
support beam to be disconnected to the brush head along at least
portions of the length of the support beam. In particularly
preferred embodiments, brushes employing the varying stiffness
techniques are made with bristle sub-assemblies that have at least
one row of bristles connected to a base string or similar structure
that functions as a support beam. The base string can be connected
across an opening in the brush, and is thus connected at its
opposite ends, or it can be connected at any number of spaced
intervals, the number and length of spacing being selected to
achieve a desired degree of stiffness.
Inventors: |
Edwards, Mark Stephen;
(Hockessin, DE) |
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: |
24301828 |
Appl. No.: |
10/358900 |
Filed: |
February 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10358900 |
Feb 5, 2003 |
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09575817 |
May 22, 2000 |
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6543083 |
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09575817 |
May 22, 2000 |
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09455308 |
Dec 6, 1999 |
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6351868 |
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09575817 |
May 22, 2000 |
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09092092 |
Jun 5, 1998 |
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6096151 |
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Current U.S.
Class: |
15/159.1 ;
15/207.2 |
Current CPC
Class: |
B29C 66/69 20130101;
B29C 2793/00 20130101; A46B 7/06 20130101; B29C 66/71 20130101;
B29L 2031/425 20130101; A46D 1/08 20130101; A46B 3/06 20130101;
A46B 5/06 20130101; B29C 66/836 20130101; A46D 3/05 20130101; Y10T
442/20 20150401; B29C 66/7392 20130101; A46B 3/00 20130101; B29L
2031/42 20130101; A46D 1/06 20130101; A46D 1/00 20130101; B29C
65/08 20130101; B29C 66/71 20130101; B29K 2019/00 20130101; B29C
66/71 20130101; B29K 2067/00 20130101; B29C 66/71 20130101; B29K
2077/00 20130101 |
Class at
Publication: |
15/159.1 ;
15/207.2 |
International
Class: |
A46B 003/00 |
Claims
What is claimed is:
1. A brush comprising: a brush head; and a bristle sub-assembly
having at least one row of bristles connected to a support beam,
the support beam, along its length, being at least partially
disconnected to the brush head and partially connected to the brush
head.
2. A brush according to claim 1, wherein the brush head has at
least one outer surface, and the support beam is connected to the
outer surface at least at spaced intervals.
3. A brush according to claim 1, wherein the support beam is
connected to the outer surface along at least a bond line that is
substantially coincident with a line of tangency between the
support beam and the outer surface.
4. A brush according to claim 1, wherein the support beam is
selected from the group consisting of a base string, a bond line
and a glue line.
Description
[0001] This application is a division of U.S. application Ser. No.
09/575,817, filed May 22, 2000, which is a continuation-in-part of
U.S. application Ser. No. 09/455, 308, filed Dec. 6, 1999 which
issued as U.S. Pat. No. 6,351,868, on Mar. 5, 2002 and U.S.
application Ser. No. 09/092,092, filed Jun. 5, 1998 which issued as
U.S. Pat. No. 6,096,151, on Aug. 1, 2000.
RELATED APPLICATIONS
[0002] This case is related to co-pending application Ser. No.
09/092,094, by Mark S. Edwards, et al., entitled "Monofilament
Bristle Assemblies And Methods Of Making Brushes Using Same," filed
Jun. 5, 1998; and co-pending application Ser. No. 09/550,657, by
Mark S. Edwards, et al., entitled "Method and Apparatus For Making
Bristle Subassemblies, filed Apr. 17, 2000 (which was based on
Provisional Application No. 60/130,883, filed Apr. 23, 1999.
BACKGROUND OF THE INVENTION
[0003] The present invention relates generally to brushes and the
art of brush making, and more specifically, to a bristle
sub-assembly in which bristles are connected at a base end to a
supporting "beam," which could take the form of a base string, a
bond line, or other structure which joins the common base ends of
the bristles together in a row. A particularly useful application
of such bristle sub-assemblies is in brush structures where
segments of bristle sub-assemblies span open areas of a brush head
or other supporting structures, and the flexibility of such
bristles is at least in part determined by torsional
characteristics of the beam.
DESCRIPTION OF THE RELATED ART
[0004] The aforementioned co-pending applications describe a method
of making bristle sub-assemblies which involve wrapping a polymeric
monofilament around a mandrel and bonding the individual wraps to
one or more base strings by applying thermal energy. According to
the aforementioned applications, an apparatus for making bristle
sub-assemblies includes a rectangular-shaped mandrel around which
is wrapped at least one continuous strand or monofilament. The
strands or monofilaments form a plurality of "wraps" which are then
placed in contact with at least one "base string," which runs
generally orthogonally to the wraps. At the points of contact
between the wraps and the base strings, ultrasonic energy is
applied to cause the individual wraps and base strings to bond
together. At a downstream processing point, cutters are used to
turn the bonded base strings and wraps into bristle
sub-assemblies.
[0005] One particularly preferred apparatus for making bristle
sub-assemblies is shown in FIG. 1, wherein the apparatus 10
includes a rectangularly shaped mandrel 12, around which is wrapped
a monofilament 14. A wrapping mechanism 16 rotates around the
mandrel 12, laying out a plurality of "wraps" 18, which are moved
vertically along the mandrel 12 by a conveyer mechanism, generally
referred to by the numeral 20.
[0006] Four base strings 22 are fed into contact with the wraps
from supply sources (not shown) near respective heating elements
24. When energy is supplied to the ultrasonic heating elements in
contact with the base string, the surfaces of the monofilament
wraps and/or the base strings, which are in contact with each
other, become plastic; after cooling, which occurs immediately
after the wraps move away from the heating elements, the wraps of
monofilament and the base strings become bonded together.
[0007] As the bonded wraps and base strings move further away from
the heating elements, they pass through cutters 26, only two of
four being seen from the view of FIG. 1. The cutters 26 slit the
bonded wraps into four bristle strings 28, each of which can be
taken up on reels (not shown) or other means for further
processing.
[0008] FIG. 2 is an enlarged view showing the point of contact of
one of the monofilament wraps 18 and one of the base strings 22.
The base string is held by a horn 30 of the ultrasonic heating
element, while a cable 32 of the conveyor mechanism 20 translates
the monofilament wraps up the mandrel 12. The cable 32 and base
string move in the same direction at the same speed, so that the
bonded wraps and base string are moved to the cutters 26 and spit
into separate bristle strings 28.
[0009] One of the bristle strings 28 is shown in FIG. 3, as having
a base string 22, and two rows 34 and 36 of bristles which are made
of the monofilament that had previously been used to form the
wraps. The bristle rows have a tendency to form a V-shape, with the
base string at the vertex of the "V." Further processing steps can
be used to render the rows of bristles parallel to each other;
alternative orientations can also be made when desired.
[0010] The details of how the bristle strings are formed, and how
they can be combined with brush bodies to form a variety of
brushes, are described in the aforementioned co-pending and related
applications, which are incorporated herein by reference. In making
brushes using the bristle strings described herein and in the
related and co-pending applications, the bristle strings are cut
into lengths that can be called "bristle sub-assemblies." These
lengths can be embedded in or otherwise attached to the brush
bodies to form a wide variety of sizes, shapes and types of
brushes.
[0011] While the bristle sub-assemblies described above have many
advantages, a continuing need exists for improved brushes and
bristles employed in same, as well as for methods and means for
varying or otherwise controlling the stiffness of the bristles
without necessarily changing the physical parameters of the
bristles themselves.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a bristle
sub-assembly in which the stiffness of the bristles can be varied
by changing one or more parameters of the beam structure that
supports the bristles.
[0013] Another object of the invention is to provide a method of
varying the stiffness of the bristles of a brush by changing one or
more parameters of the beam structure used to support the bristles
of the brush.
[0014] Still another object of the present invention is to provide
a method of changing the stiffness of a bristle without changing
the material or diameter of the bristles themselves.
[0015] These and other objects are met by providing a brush which
includes a brush body, at least one bristle sub-assembly having a
support beam having first and second opposite ends and a row of
bristles having proximal and distal ends, at least one point of
attachment between the brush body and the support beam, thereby
defining at least a portion of the bristle sub-assembly that
extends into free space, and means for varying the stiffness of the
bristles of the bristle sub-assembly.
[0016] Preferably the means for varying the stiffness of the
bristles is a physical parameter of the beam, such as
cross-sectional shape, material properties Young's Modulus, and
thickness. Additional means for varying the stiffness include
coating at least a lower portion of the bristles with a polymeric,
preferably elastomeric, material, and altering the cross-section of
the bristles, such as by tapering the end portions.
[0017] These and other objects and features of the invention will
be better understood in referencing the following detailed
description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic view of an apparatus for forming
bristle strings;
[0019] FIG. 2 is an enlarged, cross-sectional view showing the
point of contact between a monofilament wrap and a base string, in
the apparatus of FIG. 1, and approximately at the ultrasonic
heating station;
[0020] FIG. 3 is an elevational view of a bristle string which
includes first and second rows of bristles connected to a base
string;
[0021] FIG. 4 is a vertical, longitudinal sectional view, showing a
bristle sub-assembly spanning between two points on a brush head
across an opening or open space;
[0022] FIG. 5 is a vertical, transverse sectional view, taken along
line IV-IV of FIG. 4;
[0023] FIG. 6 is an end view of a bristle sub-assembly in which the
lower, or proximal, end portions of the bristles are coated with an
elastomeric material to provide additional stiffness;
[0024] FIG. 7 is a chart showing modeling of base string deflection
ratio as a function of thickness, or diameter, of the base
string;
[0025] FIG. 8 is a side elevational view of a bristle sub-assembly
connected at spaced intervals to the upper surface of a brush
body;
[0026] FIG. 9 is a side elevational view of a bristle sub-assembly,
made according to the methods and apparatuses described in the
aforementioned co-pending applications;
[0027] FIG. 10 is an end view of the bristle sub-assembly of FIG.
9;
[0028] FIG. 11 is a side elevational view of the bristle
sub-assembly of FIG. 9, after tapering the distal end portions of
the bristles, and
[0029] FIG. 12 is an end view of the bristle sub-assembly of FIG.
11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Referring to FIGS. 4 and 5, a bristle sub-assembly 38 has a
base string 40 and two rows 42 and 44 of bristles. The bristle
sub-assembly 38 is anchored to two fixed structures 46 and 48,
between which is an open space 50. The fixed structures 46 and 48
can be different parts of the same brush head, for example, where
the head defines an opening and the bristle sub-assembly 38 spans
the opening. For purposes of the present invention, the bristle
sub-assembly 38 has any length which is unbounded, or freely
spanning between opposite ends that are connected or fixed to a
relatively non-movable structure, or semi-rigid structure.
[0031] In the past, stiffness of bristles have been controlled to
some extent by varying certain parameters of the bristles, such as
their length or height, cross-sectional shape, thickness, and the
type of material used. The use of the bristle sub-assemblies made
according to the aforementioned co-pending applications has led to
the creation of relatively high aspect ratio bristle arrays,
meaning long, thin rows of bristles. These bristle sub-assemblies
have the added advantage of being cost effective to produce.
[0032] One aspect of the present invention is the realization that,
if an individual bristle sub-assembly is suspended in free space,
by attachment at its opposite ends to different points on a brush
body, another mechanism for controlling stiffness arises: torsional
movement and flexion of the base structure of the bristle
sub-assembly that imparts changes in the apparent stiffness of the
bristles. In other words, the bristles will rotate about the axis
of the base string, or other supporting "beam" structure, to
thereby feel softer to the touch. Thus, thicker diameter bristles,
for example, can be made to feel softer--or as soft as a thinner
bristle monofilament--by changing the properties of the base
string. Those properties include Young's modulus of the material
from which the base string or other beam material is made; the
diameter of the base string; the geometry or cross-sectional shape
of the base string; the length of the base string extending between
the two attachment points; and the tension imparted in the base
string.
[0033] Additional bristle action or movement can be achieved when
segments of the base of a bristle sub-assembly are allowed to span
between attached points. The length of the span can be determined
by the type of brush envisioned, such as a toothbrush as opposed to
a vacuum brush, the overall size, and the degree of movement
desired. For a given material, base string geometry and diameter,
bristle diameter and bristle height, all held constant within a
bristle sub-assembly, the softness of the bristles will vary
according to position along the non-attached segment of the bristle
sub-assembly, with the first and last bristles having the highest
stiffness and the center bristles being the most soft.
[0034] The continuous change in sensible stiffness for a constant
force applied along the suspended length is produced by the
differential displacement of each bristle tip according to the
cumulative contributions generated from the bending of the bristle,
the degree of rotation of the base string (torsional motion) at the
base of the bristle, the bending or flexion of the base string at
the bristle base, and the selection of material properties for the
base string. Bristles within a bristle sub-assembly, located at or
juxtaposed the anchoring point to the brush head have limited
motion, primarily bending motion and are similar to bristles tufted
into a tuft hole of a conventional brush. While the bristles
located near the anchor point exhibit movement similar to that of a
conventional brush, bristles more distant to the anchor point
exhibit an increasingly lower stiffness value (higher movement) due
to the contribution of the base string component.
[0035] The base string described above can be a separate strand of
material, as in the preferred embodiments of the prior co-pending
applications, or other "beams" can be formed by the fused area of
bristles not connected to a base string, such as when bristles are
laid side by side and fused together at the base. The fused area
becomes the beam or base string. A glue line or extrusion line
could also be used to form the beam.
[0036] By mixing and matching the parameters described above, one
can achieve virtually any desired degree of bristle stiffness. The
bristle sub-assembly product can be customized to a stiffness range
by combining physical dimensions, and whether they are solid or
have voids. The span distance between anchor points and to some
degree the tension will also contribute to customizing the range of
movement.
[0037] The bristles in a linear bristle sub-assembly, such as those
described in the co-pending applications, are freer to move than
bristles densely packed in a conventional tuft hole. Conventional
tufting techniques pack tens of bristles into a single hole. The
hole can be of many shapes but what is common to all is a low
aspect ratio with a circular hole having an aspect ratio of 1.0 and
oval or rectangular holes having aspect ratios of up to 10. When
packed into these holes, most bristles are in contact with and thus
have friction with neighboring bristles on many or all sides. This
increases bristle stiffness of a given diameter bristle through the
support provided by these neighboring bristles and effectively
shortens the length which is free to move. By comparison, a bristle
sub-assembly according to those described herein have relatively
large aspect ratios. Therefore, an individual bristle has fewer
neighboring bristles to interact with and be supported by, and
thus, is less stiff.
[0038] Referring to FIG. 7, modeling of Nylon brush filaments was
performed and the results are presented. A Nylon bristle diameter
of 0.006 inch was used as a constant, while the base string was
varied, using steel as the base for comparison to a torsionally
"stiff" material. On the horizontal axis, the distance along the
base filament is shown in inches. Attachment is assumed over a one
inch span, with peak deflections shown at the mid-point between the
span. The steel base string is shown to have no deflection, due to
its inherent properties and the force applied. However, the degree
of deflection increases with thinner diameter, lower modulus,
polymeric base strings. In conclusion, it can be seen that bristle
deflection varies from end bristle to center bristle, and that the
base filaments deflect only slightly. Moreover, deflection is the
sum of bristle cantilever bending plus base filament rotation, and
base filament diameter has a large influence on bristle
deflection.
[0039] The use of a spanning bristle sub-assembly, or for
connecting a bristle sub-assembly at different points while leaving
portions unconnected, has numerous possible uses in different brush
types. For example, in a vacuum attachment, an open brush head
attachment would allow the air to flow up through the bristle
structure and keep air flow resistance to a minimum since the
bristles do not need to be continuously embedded in a support
structure. In this case, high torsional stiffness may be preferred
for general cleaning so there is little torsional deflection across
the length of bristles.
[0040] In some abrasive brush applications, the use of the side of
the bristle is preferred over the tip of the bristle. When
relatively large bristles are used they do not bend easily and
therefore are limited more to the tip. By attaching them to a
supporting base structure which torsionally twists under load, the
bristles would then tend to lay away from the direction of rotation
and expose more of the bristles side, thus increasing the contact
area between the work and the bristles (thereby gaining
efficiency).
[0041] In cleaning brushes, brushes used in applications such as on
the end of a garden hose for car washing should be soft while
allowing the fluid (cleaning solution or rinse) to work together
with the bristles. A preferred attachment would allow the solution
to be discharged at the base of the bristles. This serves to not
only continuously wet the bristles but to cleanse the bristles from
entrapping harmful dirt particles. Soft bristles are required to
prevent damage to the car finish. The sides of a bristle will do
less abrasion to the finish than the pointed ends of a bristle.
Therefore more rigid (aggressive) bristles could be used if they
torsionally deflect to expose the bristle side rather than the
tip.
[0042] In other brush designs, a bristle sub-assembly which has a
sufficiently stiff base structure may not need a supporting head or
wire as is typically understood in the art. The base structure of
the sub-assembly could be directly attached to a handle such as in
a mascara brush or bottle brush. With the proper cross-section of
the base structure to which the bristles are attached, the base may
be relatively stiff to bending, yet torsionally soft. This would
allow the bristles to be stiff using an axial movement and soft
using a rotational movement.
[0043] In general, the bristle sub-assemblies need not be connected
at the ends of the base string, as would be the case where a
bristle sub-assembly is suspended across an opening in a brush head
or other supporting structure. For example, in FIG. 8, a bristle
sub-assembly 64 includes a base string 66 and a row of bristles 68.
In this case, the bristle sub-assembly is connected to an upper
surface of a brush head 70 at spaced intervals, such as by spot
welds 72, 74 and 76. Consistent with the teachings above, the
bristles nearest the spot welds will have the greatest apparent
stiffness, due to the spot welds' limiting effect on the amount of
torsional movement of the base string 66. However, the amount of
limitation provided by the spot welds can be controlled by
controlling the amount of surface area of the base string that is
covered by weld material. A complete covering of the base string
with weld material will have a maximum limiting effect.
[0044] The spot welds can be formed by any conventional means,
including ultrasonic heating (assuming one or both of the bristles
and base string are made of polymeric material), adhesive bonding,
conventional heating (coupled with plastic deformation), and
virtually any other suitable means. Also, if the base string 66 is
connected continuously along the surface of the brush body, along a
weld line, or glue line, if the connection is only at the tangent
point between the base string 66 and the surface, the bristles will
appear less stiff due to the torsional movement of the base string
which is permitted by the fact that the base string is not
completely bound throughout its circumference. Thus, controlling
the circumferential degree of binding of the base string to the
underlying brush structure will result in controlled stiffness.
[0045] For some applications, very fine filaments are preferred for
their softness and their ability to penetrate small areas, such as,
in the case of a toothbrush, small interdental and gingival areas.
Their small cross-section, however, makes them weak and less
durable when used in a toothbrush. Thus, another aspect of the
present invention is to provide an elastomeric coating to a bristle
sub-assembly which reinforces the filaments of the bristle
sub-assembly from the bonded area up to a predetermined height. The
height is selected to yield the desired stiffness of the tuft. This
structure would resemble that of a used paint brush improperly
cleaned, where the base portions of the bristles becomes thicker
than the distal end portions, due to drying and hardening of paint
on the base portions.
[0046] The coating of bristles permits fine filaments such as 2-5
mil filaments to be used entirely within a tuft and have the
apparent stiffness of larger diameter filaments such as 6-10 mil.
FIG. 6 illustrates such a coated bristle sub-assembly 52, in which
the two rows of bristles 54 and 56, connected at their proximal
ends to a base string 58, are provided with polymeric coatings 60
and 62 along the proximal end portions of the bristles. The length
to which the coatings extend, as well as their thicknesses are
material properties, such as hardness, will determine the amount of
stiffness added to the fine bristles.
[0047] The coatings can be elastomeric resins or other suitable
materials. They could further provide functionality with respect to
a wear indication, bactericide or other desired properties
difficult to incorporate into the monofilament bristle itself. The
elastomeric resin coating can reduce the possibility of bristle
shedding from the bristle sub-assembly, by adding additional
adhesion between the base string and the bristles. It could also be
used by the brush maker as a bonding agent in the process of making
brushes, particularly where techniques that do not employ base
strings are employed.
[0048] The non-bonded end of the bristle sub-assemblies would not
be coated, nor attached to the adjacent filaments. Such a structure
would have similar performance to a tapered filament. This
structure would also tend to resist splaying. The stiffness of a
given filament would be determined by the relative viscosity of the
resin used, the thickness to which it is applied, and the area
(height) to which the bristle is treated. Coatings would have
particular applicability to toothbrushes, which are limited to a
minimum of 5 mil bristles. These small diameter brushes have
relatively shortened periods of useful life, due to wear that leads
to splaying. In conventional tufted brushes, it would difficult if
not impossible to apply thin coatings to the bristles, due to the
packing of bristles in a dense tuft hole, nor can select bristles
be coated for the same reason. Using the bristle sub-assemblies
described herein as well as in the co-pending applications, the
brush maker can apply thin coatings onto pre-selected portions of
the bristle/tuft.
[0049] To form the coatings on the bristles, the individual strands
could be individually coated or stuck together for some given
length, leaving the remaining length free, by solution coating, or
by hot melt coating with a polymer having a lower melt point. The
solution coating could be, as described in the Nylon Plastics
Handbook by M. I. Kohan, pp286,287, Dupont's Elvamide.RTM.
terpolymers such as a 6/66/610 or 6/66/69. Terpolymers are soluble
in hot methanol or methanol/water solutions. These are typically
used for thread bonding.
[0050] The hot melt coatings could be Low melting nylon such as
those made for hot melt coating. An example is Platamide H105, a
6/66/12 nylon terpolymer by Elf Atochem or Griltex.RTM.1 from EMS.
Additional examples include Pebax.RTM. nylon elastomer by Elf
Atochem to thermally bond to nylon filament, and Hytrel.RTM.
polyester elastomer to thermally bond to polyester filament.
Further examples include low melting materials grafted with
reactive material such as maleic anhydride. An example is
Kraton.RTM. FG1901X, a SEBS block copolymer modified with maleic
anhydride. An example of glues that could be used herein are
cyanoacrylate, sold commercially as "Super Glue."
[0051] FIGS. 9 and 10 illustrate a bristle sub-assembly 78 which,
as in the previously described sub-assemblies, includes a base
string 80 and two rows 82 and 84 of bristles. The scale shown in
FIGS. 9 and 10 is exaggerated to highlight features at the proximal
ends and distal ends of the bristles. Also, the base string is
shown to be rectangularly shaped and disposed between the rows of
bristles, although virtually any shape can he employed. Also, the
base string can be any device that acts as a support beam for
suspending the bristle sub-assembly across openings, or simply for
supporting the beam at select positions to allow the beam to
undergo torsional movement during brushing action of the
bristles.
[0052] As seen in FIGS. 9 and 10, the distal end portions of the
bristles are sheared and have substantially the same thickness as
the proximal ends that are connected to the base string 80.
According to the present invention, the stiffness of the bristles
can be changed by mechanically abrading the distal end portions to
provide a taper, as shown in FIGS. 11 and 12. The abrading process
provides a tapered portion 86 for the bristles that can go down the
length of the bristles approximately 33% of the overall length.
[0053] Tapering changes the apparent stiffness of the bristles. For
example, a 10 mil filament can be worked with an abrasive belt to
undergo a reduction down to 10% of its original diameter, for
example, to result in a 1 mil thickness at the tip. The taper can
begin as far down the bristle as 33% of the overall length. Beyond
that, the limits are efficiency, in that it may be more efficient
to begin with a thinner bristle than to taper more than 33% of the
overall length.
[0054] While an abrasive belt is one method of abrading and thus
forming the taper on the bristle distal end portions, other means
can be employed.
[0055] The present invention has been described above with
reference to preferred embodiments. However, those skilled in the
art will recognize that changes and modifications can be made in
these preferred embodiments without departing from the scope of the
present invention. Accordingly, these and other changes and
modifications which are obvious to those skilled in the art are
intended to be included within the scope of the present
invention.
* * * * *