Note: Descriptions are shown in the official language in which they were submitted.
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R~TARY BRUSH ~II TH REMOVABLE E~RUSH EL~:MENTS
ackground of the Invention
1. Field of the Invention
The invention relates to rotary brushes, and in
particular, to rotary brushes with removable brush elements.
Rotary brushes which employ an annular display of
bristles have been utilized in a number of applications for
the surface finishing of various objects. Such brushes have
been used in industrial applications to deburr and/or
otherwise provide a surface finish to various manufactured
articles.
2. Description of the Prior Art
Rotary brushes are known for surface finishing
applications which include a circular hub onto which
abrasive loaded filaments are adhered by a layer of cured
resin which binds one end of each filament with the opposite
end being displayed outward. While such brushes have found
great commercial success, the process by which they are made
provides certain limitations. First, the brushes are
t~pically made by orienting the individual filaments in a
flocking operation to stand erect with one end in a layer of
liqu~d resin which is then cured to provide the brush
element. The flocking operation generally llmits the trim
length of the bristles to less than about 12 cm. Secondly,
some of the cured resins used to hold the bristles degrade
in the presence of solvents and hot aqueous solutions which
may contain acidic or caustic agents, freeing or weakeninq
the bond with the bristles. Finally, the adhered bristles,
when deployed on a rotary hub, tencl to fail by flexural
fatigue at the point where the bristle emerges from the
cured resin, caused by repeated deflection and return to
normal, as the individual bristles are contacted with the
object being finished and such contact is broken as the
wheel rotates. This is also a problem with the bristles of
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brushes that are held on the surface of a hub by mechanical
means.
U.S. Patent No. 4,646,479 and its United Kingdom
counterpart U.R. Patent Application GB2 106 020 A, published
April 7, 13B3, discloses a deburring cylindrical brush which
includes a mandrel having attached to it a multiplicity of
long abrasive bristles wherein the population density of
bristle~ on the brush is such that the outwardly-extending
ends can readily flex both in the plane of rotation and
sideways along the lengthwise dimension of the brush.
Bristles at their midpoint are wrapped around a rod which is
mechanically held in place on the mandrel peripheral surface
by spaced flange elements. This results in a brushing
surface wherein the bristles attach in fixed position at the
face of the mandrel and are subject to flexural fati~ue as
they deflect in use. After repeated such deflections, the
bristles tend to break off at the point of attachment.
While various references disclose finishing wheels
comprising a rotary hub having a slotted peripheral surface
with abrasive packs inserted into each slot to provide an
abrasive flap wheel, none are known to employ bristles in
place of abrasive flaps. Each abrasive pack contains like
oriented abrasive flaps and the collection of flap packs
provide6 an annulus of abrasive flaps around the hub. Such
flap wheels are disclosed, for example, in U.S. Patent Nos.
3,768,214, 4,217,737 and 4,285,171.
Summary of the Invention
The invention provides a rotary finishing wheel
which has a hub from which a radial display of bristles
emanates. The bristles are attached in a unique manner to
greatly red~ce flexural fatigue failure, thereby extending
the useful life of the brush over brushes of the prior art
which have their bristles attached in a conventional manner.
3 It is also possible to obtain brushes with bristles longer
than 12 cm since the method of making the brushes of the
present invention does not rely on a flocking process.
' 3 ~ 60s57-3~56
~ ore specifically, the invention provides a removable
brush element for installation on a rotary hub, said brush
comprising: (a~ a brush comprising a plurality of resiliently
flexible bristles and bristle holding means for holding said
bristles in normal generally parallel outwardly projecting
orientation relative to said bristle holding meansî (b) an
elongate anchoring means mechanically engagable with a brush
fastening means on said hub; and (c) a resiliently flexible
element having a first end fastened to said anchoring means and an
opposite end fastened to said holding means to position said
holding means in a rest position relative to said hub, the
relative flexibility of said bristles and said flexible element
permitting said flexible element to deflect at a greater angle
from said rest position than the angle of deflection of the
bristles of said brush from said normal position when said hub is
rotated with said bristles in contact with a workpiece, wherein
the angle of deflection of said resiliently flexible element
varies from 0 in a rest position to about 55 as said rotary
brush is rotated with said bristles in contact with a workpiece
and the angle of deflection of said bristles varies from 0 in
said normal orientation to about 15 when said rotary brush is
rotated with said bristles in contact with a workpiece whereby
bristle loss due to flexural fatigue failure is greatly reduced.
The invention also includes a rotary brush that includes
a brush element as aforesaid having spaced brush fastening means.
A plurality of removable brush elements are fitted usually with
one brush element being attached by one brush fastening means to
provide a radial array of brushes. The preferred hub includes
generally a cylindrical hub having a peripheral surface and
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1J:: 2~73~
3a 60557 3456
opposite end surfaces. The hub has a plurality of axially
extending circumferentially spaced slots opening through the
peripheral surface with one brush element in each slot. The brush
elements comprise a brush having a plurality of resiliently
flexible bristles and a bristle holding means for holding the
bristles in a normal generally parallel outwardly projecting
orientation relative to the bristle holding means. Each of the
brush elements also includes an elongate anchoring means adapted
to be engaged in one of the brush fastening means. The brush
elements also include a resiliently flexible element having a
first end fastened to the anchoring means and an opposite end
fastened to the holding means to position the holding means in a
radial rest position relative to the hub. The relative
flexibility of the bristles and the flexible element permits the
flexible element to deflect at a greater angle from the rest
position than the angle of deflection of the bristles of the brush
from the normal position when the hub is rotated with the bristles
in contact with an object being finished.
The preferred bristles are abrasive-loaded polymeric
bristles.
Brief Description of the Drawinas
Figure 1 is an end view of a rotary brush of the present
invention.
Figure 2 is a fragmentary end view showing one brush
element of the type depicted in Figure 1 in place on a hub which
is partially broken away;
Figure 3 is a fragmentary end view which shows a
conventional way of fastening filaments to a hub illustrative of
that known in the prior art;
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Fig. 4 is a fragmentary end view of another
embodiment of the rotary brush of the present invention,
again showing a single brush element, with the hub being
partially broken away;
Fig. 5 is a fragmentary end view of the brush
element depicted in Fig. 1, except as it would appear in
counter-clockwise rotation to show the relatlve deflection
of the brush element and the bristles.
FigO 6 is an end view of some parts of one
embodiment of a bristle holding means;
Fig. 7 is an end view of the parts of Fig. 6 after
assembly;
Fig. 8 is an end view of the parts of a brush
element in partial assembly; and
Fig. g is an end view of the fully assembled brush
element assembled from the parts shown in Fig. 8.
Detailed Description
Referring now to Figs. 1 and 2 of the drawing,
rotary bru6h 10 is shown having a cylindrical hub ll which
has a slotted peripheral surface 12 to provide slots 13
through surface 12 for holding a plurality of brush elements
14 with one brush element 14 in each slot 13. Brush element
14 lncludes a brush 15 comprised of a plurality of
resiliently flexible bristles 16 and a bristle holding means
17 for holding the bristles in a normal generally parallel
outwardly projecting orientation relative to bristle holding
means 17. Brush element 14 includes at the end opposite
brush 15 an elongate anchoring means 20 adapted for
engagement in one of slots 13. A resiliently flexible
element 21 having a first end 22 fastened to anchoring means
20 and an opposite end 23 fa6tened to holding means 17
positions which holds holding means 17 in a radial rest
position relative to the hub 11.
As shown in Fig. 5, the relative flexibility of
bristles 15 and flexible element 21 permits flexible element
21 to deflect at the greater angle (A) from a rest position
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within A' than the angle ~8) of deflection of the bristles
16 of the brush 15 from a normal position B' as the hub 11
is rotated with bristles 16 (shown as a single bristle) in
contact with a workpiece (not shown). This relative
deflection substantially reduces bristle flexural fatigue.
Hub 11 is generally cylindrically shaped and adapted
for rotation on a suitable arbor, not shown, and is made of
a suitable material capable of withstanding the rotational
forces and mechanical movement of brush elements 14 as
rotary brush 10 is rotated under normal working conditions.
Suitable materials for forming hub 11 include any of various
metals such as aluminum, iron and alloys of iron such as
steel, brass, and the like, high modulus plastic materials
1~ such as nylon, and the like. The preferred material for
making hub 11 is aluminum.
The dimensions of hub 11 will depend upon the
particular application and may vary considerably~ The
diameter of hub 11 typically is on the order of 5 to 30
centimeters. The length of hub 11 typically varies from 3
to 200 centimeters, although shorter and longer lengths are
also contemplated.
The number of slots in peripheral surface will also
vary, depending upon the diameter of the hub and upon the
2S size of the brush elements. With thicker brush elements and
smallee diameter hubs, fewer brush elements are required
while larger diameter hubs and thinner brush elements
generally require the use of more brush elements. The
number of brush elements should be sufficient to provide an
adequate radial display of bristles for the particular
application. Typically, the number of brush elements will
be on the order of 12 for a 5 cm diameter hub to on the
order of 60 for a 30 cm diameter hub. It is contemplated
that not all of the slots need be fitted with brush
elements. For example, alternate slots could be empty or
they could contain other types of treating implements such
as an element formed of low density abrasive products such
as that available under the trade designation "Scotch Brite"
or they may be coated abrasive flaps or strips.
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Additionally, while the typical deployment of slots
is parallel to the axis of rotation, the deployment may be
altered to obtain specific results. For example, the slots
may be helical in nature as disclosed in aforementioned U.S.
Patent No. 4,285,171 or they may be angled with respect to
the axis of rotation.
Slot 13 preferably is enlarged below peripheral
surface 12 and open to at least one of the end surfaces of
hub 11 so that an appropriately shaped anchoring element 20
(such as a metal rod) may be slipped in from the opening in
the end ~urface to mechanically engage a loop of anchoring
element 20 in hub 11 to prevent the loop from being
dislodged from hub 11 as the abrasive wheel is rotated.
Alternatively, the enlarged portion of anchoring element 20
and re6iliently flexible element 21 may be molded a6 a
unitary structure of a moldable material, e.g., nylon, or
may be otherwise shaped into a unitary structure, e.g., by
machining or by any other suitable means.
Other hub designs may also be useful and they need
not have 610ts for attachment of the brush elements. For
example, the hub disclosed in U.S. Pat. No. 3,768,214 may be
employed. This patent is incorporated herein by reference
for lts teaching of the hub construction. It should be
noted that, if such a hub is employed, a corresponding brush
anchoring element also disclosed should be employed.
Resiliently flexible bristles 16 are preferably
formed of polymeric material6 6uch a6 nylon which is
preferably loaded with abrasive particles. Other materials
may also be employed to form bristles 16, e.g., non-abrasive
polymeric materials, abrasive or non-abrasive wires or the
like. The abrasive particles which impregnate bristles 16
are preferably formed of silicon carbide or aluminum oxide
although other known abrasive materials are also useful such
as ceramic abrasive material (e.g., sold under the trade
designation "Cubitron") and fused alumina-zirconia abrasive
material such as that sold under the trade designation
"NorZon". The fiber length preferably is at least 12 cm,
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but it may vary from about 2 cm t~ about 25 cm in lsngth.
Longer and shorter fiber lengths are also po~sible. The
fiber diameter may also vary considerably but it typically
is within the range of 0.5 to 1.5 mm.
Suitable abrasive fibers are readily commercially
available. For example, the E. I. DuPont deNemours Company
markets a nylon abrasive filament useful for this purpose
under the trade designation "Tynex", such as Tynex A0376,
0378, and g376, filled with silicon carbide abras~ve, and
Tynex A9336, filled with aluminum oxide abrasive. These
fibers are commercially available in fiber diameters on the
order of 18-60 mils (average diameter of about 0.5 to 1.5
mm) containing abrasive particles having a size of about 30
to 600 grade ~average particle size of about 20 to 600
micrometers) with a weight percent loading of abrasive on
the order of 30-40%. The fibers are available on spools or
in hanks in lengths of up to about 100 cm. Similar useful
fibers are available from the Allied Fibers Company under
the trade designation "Nybrad". Any of these fibers may be
crimped.
The abrasive particle size which ~s loaded into the
bristle 16 will vary in size, depending upon the diameter of
the bristle 16, with smaller diameter particles being
employed in smaller diameter filaments, but generally the
abrasive grade size is in the range of about 30 to 600
grade. The loading of abrasive material in the fibers
likewise may vary considerably, but it is preferably in the
range of 10 to 20% by volume.
The fiber holding means is any convenient way to
hold the bristles 16 in place in the proper orientation
without undue bristle loss during rotation. Bristle holding
means 17 may include a block of cured resin which holds a
collection of previously deployed fibers. A preferred
bristle holding means is provided as depicted in Figs. 6-9
by folding a plurality of filaments 32 at their midportion
about a fiuitable element 30 and grasped between the opposed
edges of a suitable metal channel 31 which is mechanically
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engaged over the folded end of the filaments to hold the
same in place.
Fig. 4 discloses yet another method of holding the
bristles 16 in place which employs spaced sheets 40 formed
of any suitable material such as paper or cardboard having
therebetween a bundle of filaments to provide a stack which
is mechanically fastened by suitable means such as staples
41 and may be further reinforced by application of or
immersion in a suitable curable resin.
Flexible element 21 can be provided by any of a
variety of ways. For example, it may be a thin piece of
plastic or metal which is sufficiently flexible yet somewhat
rigid or it may be provided by a folded strip of metal or
fabric 60 e.g., formed of nylon fibers, as depicted in Fig.
6-9. A particularly useful strip material is a polymer
reinforced fabric made with nylon.
The angle (A) of deflection of resiliently flexible
element 21 will typically vary from ~r in a rest position,
to about 55, as the wheel is rotated with the bristles in
contact with a workpiece. Similarly, the an~le (~) of
deflection of the bristles 16 will typically vary from about
0 to about 15, with the bristles 16 in contact with the
workpiece. Deflection will, of course, depend upon the
degree of contact and the relative flexibility of each of
the materlals but the angle (A) of deflection of the
flexible element 21 will always exceed the angle ~B) of
deflection of the bristles 16.
Examples
The invention is further illustrated by the
following examples wherein all parts are by weight, unless
otherwise stated.
Example 1
A 20 brush, 20 inch (51 cm) outer diameter, 4 inch
(10 cm) wide rotary brush wheel of the type depicted in
Figure 1 was prepared. Although crimpinq of a folded
collection of fibers within a metal channel can be achieved
continuously with a series of crimping rolls, crimping of a
9 ~ ~ 2~ 73~
laid out series of fibers 10-12 fbers de~p was achieved in
a table vise. The metal channel was formed of ASTM A366 18
gauge (0.046 inch, 1.2 mm) dead soft, cold rolled steel to
provide a U-shaped cross section with a 1/2 inch (13 mm)
base and 1/2 inch (13 mm) legs (approximate dimensions).
The fibers were 0.04 inch (1 mm) diameter abrasive-loaded
crimped fibers containing 80 grade (average particle size of
about 200 micrometers) Al2O3 abrasive granules, the fibers
being commercially available as DuPont "Tynex" fibers.
Channel (31) was preformed in a sheet metal brake. ~ 31x32
basket weave, 7.4 oz./yd2 (251 g/m2), 17 mil (0.43 mm) thick
nylon fabric which had been reinforced by saturating with
about 21 grains per 4x6 lnch area (88 g/m2) and backsizing
with about 30 grains per 4x6 inch area (125 g/m2) poly-
urethane was folded, sewed to form loop (60), and adhesively
bonded to the metal channel (as depicted in Figs. 7-9). The
fiber loading was depressed into the metal channel using a
core rod (30). Final crimping of the metal channel locked
core rod (30) and the fiber mid portions inside the metal
channel.
Example 2
A 15 brush, 9 inch ~23 cm) outer diameter, 2 inch ~5
cm) wide, rotary brush wheel having a 3 inch (7.6 cm)
diameter hub of the type depicted in Fig. 4 wa8 prepared. A
collection of 2-1/2 inch (6.4 cm), 0.035 inch (0.89 mm)
diameter uncrimped DuPont "Tynex" fibers (impregnated with
180 grade, about 80 micrometers in average particle cize,
SiC abrasive grains) 10 to 12 fiber diameters deep was laid
out to the desired length. One inch t2.5 cm~ of one end of
the fiber collection was immersed in a 2-part curable
thermosetting polyurethane resin to bond the fiber
collection ends together. A second similarly prepared array
of fibers was prepared and the two bundles were placed on
either side of a reinforced nylon cloth of the type
described in Example 1. Two exterior supportive panels of
20 mil (0.5 mm) thick fiber paper, commercially available as
Vulcanized Fibre from NV~ Company, surrounded the two
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bundle6 and hinge end. The total composite a~sembly wa~
permanently combined by a series of metal staples. Other
means of fastening that could have been employed include
stitching, rivets, or similar devices.
Control Example
A commercially available BrushlonTM 9 inch (23 cm)
diameter brush band 2 inches (5 cm) wide with a 1 1/2 inch
(3.8 cm) fiber trim length of 0.035 inch (0.89 mm) "Tynex"
fibers adhered thereon by polyurethane resin was held
between flanges to provide a cylinder brush wheel.
Evaluation
The brush of Example 1 was run continuously for 300
hours on a laboratory tester at 2~0 rpm in a 3/4 inch (about
19 mm) interference contact with a metal workpiece, with no
bristle loss and no evidence of fiber fatigue. A control
brush of similar size employing the method of attaching the
brush element depicted in Fig. 3 run under the same
conditions also had no fiber loss but exhibited fiber
movement in use which would result in fiber fatigue and
failure if the brush would have been run for a longer period
of time.
The brush of Example 2 was run continuously for 12
hours on a laboratory tester at 1800 rpm in a 1/4 inch
(about 6 mm) interference contact with a metal workpiece
with no bristle los~ and no evidence of fiber fatigue. The
brush o~ the Control Example was run on the same equipment
under equivalent conditions but before 12 hours usage it had
lo~t all of its bristles with failure by breakage at the
fiber base near the point of attachment.
While the principle6 of the invention have been made
clear in illustrative embodiments, there will be immediately
obvious to those skilled in the art many modifications of
structure, arrangement, proportions, the elements,
materials, and components u~ed in the practice of the
invention, and otherwise, whlch are particularly adapted for
specific environments and operative requirements without
departing ~rom those principles. The appended claims are
3 ~
intended to cover and embrace any and all such
modifications, within the limits only of the true spirit and
scope of the invention.
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