Note: Descriptions are shown in the official language in which they were submitted.
!ilETHOD OF i~lANU _CTURE OF BRUS~ PON_N~S
This invention relates to improvecJ methods oF
rnanufacturing brush components, the components themselves,
and brushes made From the components.
In U.K. Patent Specification No.730131, a method oF
manufacturing brush strips is disclosed wherein an organic
material is heated to plas-tic state and is extruded through
a mouthpiece into a continuous U-shaped strip through a
groove-shaped guide member, whereupon a plurality of
aligned bristles are conveyed by means of an end~ess belt
together with a thread of metal and are folcled around a
guide cam and led into -the open-topped guide member. The
guide member has a tapering slo-t in its upper surFace at
the bristle feed-in location, and as the bristles are
advanced and the U-shaped strip is pulled out of the guicle
member, so the bristles are folded with their ends upwards
by thr- narrowing slot, and ?ressed down into the U-shapeci
strip. In this way, the side walls oF thr- U-shaped
strip are pressed against the bristles which are partly
pressed into the soft material oF the strip and neld therein.
It is preferred that the strip is cooled on emergence from
the extruder so that it maintains its shape better.
Brush strips màde in accordance with -the above
teachings are wholly unsatisfactory in that, due to the
- 25 1QW temperature of the U-shaped strip, the bristles are
only pressed into its surFace and cannot even form a
satisfactory mechani-cal key with the strip. This means
that after a few uses, the bristles tend to fall out of the
strip.
In our U.K. Patent Specification No.1457074, another
method of manufacturing brush strips is disclosed wherein
a plurality of endless filaments are formecl into a filament
bundle, the bundle is Folded upon itself into a zig-zas
formation and a plurality of threacls are then knit-ted into
the zig-zag formation so as to hold it tngether with
adjacent arms oF the zig-zas attached together by the
threads. A locking device which rnay be an extruded bead
is then located on each side edge of the zig-zag Forma-tion
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so as to form a mechanical bond therewith, and to
provide two brush strips the zig-zag formation is slit
down its centre.
Brushes made in accordance with the teachings of
this specification are satisfactory but because only a
mechanical interlock is provided between the bead and
edges of the zig-zag formation, it is essential to have
a knitted zig-zag formation with U-shaped portions
along each side edge, otherwise the bristles can pull
out of the brush strip during use.
Accordingly, one disadvantage of this method of
manufacture is the necessity to have to provide
specially knitted zig-zag formations of endless
filaments.
In U.K. Patent Specification No. 195679, endless
belts are disclosed for transporting cut bristles from
one location to another.
In U.K. Patent Specification No. 610657 brush
strips are shown formed from cut bristles but the
bristles are held in the form of a strip by bands of
metal located on either side of the bristles and
clamped together.
It is the object of an aspect of the present
invention to provide a brush manufacturing method which
overcomes the disadvantages of the prior art and allows
brush components to be manufactured using cut bristles
by a quick and largely automatic method which is
relatively cheap to operate.
According to one aspect of the present invention,
we provide a method of manufacturing a brush component
comprising feeding a plurality of predetermined lengths
of synthetic resinous brush bristle from a supply into
the nip of at least one pair of endless haul-off belts
so that said bristles are arranged in an adjacent array
substantially parallel to each other with their ends
substantially in line, the array being of substantially
uniform thickness and density, passing the array
through an extruder, heating the array along its length
so as to at least soften the bristles in a
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predetermined area, extruding synthetic reslnous
material onto both sides o~ the array
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along its length over said predetermined area so as to
penetrate between any unfused bristles in saicl area an~
so as to hold the bristles together, and folding or
slitting the bristles substantially along the centre
of the array after they emerge from the extruder to
provide said brush component or components.
Preferably, the ends of the bristles are tarnped
to give a uniForm width and to align them prior to passing
them From a feeder into the nip of the haul-off belts.
PreFerably,the synthe-tic resinous material is a
thermoplastic material which is cooled so as to set prior
to the slitting operation taking place.
Preferabiy also, the material is the same material
as that of the bristles.
Preferably~ the bristles are heated to a temperature
which is sufFicient to fuse them together prlor to the
extrusion step.
In one form of the invention, a single pair of haul-
! off belts grip the array oF bristles centrally so that the
2û ends of the bristles projec-t beyond the edges of the belt
and a strip of synthetic resinous material is extruded
along and around the two side edges of the array so as to
hold the respective ends oF the bristles together,
whereupon, on emergence from the nip, the bristles are slit
centrally to form -two continuous brush componen-ts.
According to a second Form of t~e invention, the
bristles are fed into the nip of two spaced pairs of haul-
off belts which respectively support the array oF bristles
along the two e`dges of the array, that is support the two
ends of the bristles, whereupon two beads oF synthetic
resinous material of different widths are extruded along
the centre line oF the array of bristles, one bèad being
located on one side oF the array and the other on the
opposite side, and while the synthetic resinous beads are
still soft, the array of bristles is folded upon itself
along the line of the beads with the wider bead outermost,
the folded bristla array and beads being passed through a
forming roiler, wnereupon the soft material is cooled
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and allowed to harden.
Preferably, -the bristles are partly or completely
impregnated with the resinous material at the extrusion
stage. However, when the array is passed through the forming
roller, impregnation will occur, or be completed. Of course,
where the heating step causes complete fusion, impregnation
can only occur around the fused portion.
According to a third form of the invention, the
bristles are fed into the nip of two spaced pairs of haul-
off belts which support the ends of the bristles, whereuponequal volumes of synthetic resinous material are extruded
onto the two faces of the bristle array along its centre
line between the pairs of haul-off belts at a pressure
sufficient to penetrate and impregnate the array of bristles,
whereupon the synthetic resinous material is allowed to
cool and the array is then slit centrally down the centre
line of the synthetic resinous material so as to provide
two continuous brush components.
Other aspects of the invention are as follows:
A method of manufacturing a brush component com-
prising feeding a plurality of predetermin~d lengths of
synthetic resinous brush bristle from a supply into the
nip of at least one pair of endless haul-off belts so that
said bristles are arranged in an adjacent array substantially
parallel to each other with their ends substantially in
line, the arra~ being of substantially uniform thickness
and density, passing the array through an extruder, heating
the array along its length at a central location so as
at least to soften the bristles in this location, extruding
synthetic resinous material on both sides of the array
along its length over the softened bristles so as to penetrate
any unfused areas between the bristles and to hold them
together and folding the bristles substantially along the
centre of the array after they emerge from the extruder
to provide said brush component.
A method of manufacturing a brush component com-
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pris.ing feeding a plurality of predetermined lengths ofsynthetic resinous brush bristle rom a supply into the
nip of at least one pair of endless haul-off belts so that
said bristles are arranged in an adjacent array substantially
parallel to each other with their ends substantially in
line, the array being of substantially uniform thickness
and density, heating the array of bristles along its length
so as to fuse together the bristles so as to hold them
together and folding or slitting the bristles substantially
along the centre of the array after they emerge from the
heating step, and allowing the fused bristles to cool so
as to provide said brush component.
The invention also extends to brush components
when made by any of the above-described methods and to
brushes formed from said brush components, and to the manu-
facturing ~pparatus.
The invention is now described by way of example
with reference to the accompanying schematic drawings,
in which:-
FIGURE 1 is a perspective view of an array of
bristles;
FIGURE 2 is a perspective view showing the array
of bristles passing into the nip of a pa.ir of haul-off
belts in accordance with a first form of the invention;
FIGURE 3 is a perspective view showing a split
extrusion die extruding beads of material onto and around
the two edges of the array,
FIGURE 4 is a perspective view showing the array
being slit centrally;
FIGURE 5 is a perspective view of one of the brush
components manufactured in accordance with the steps
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shown in Figures :L-4;
FIGURE 6 is a vicw similar to Figure 3 showing an
alternative extrusion operation in accordance with a
second form of the invention;
FIGURE 7 is an end view showing the array of
bristles after a subsequent folding operation;
FIGURE 8 is an end view showing the folded array oF
bristles being passed through forming rollers;
FIGURE 9 is an end view showing the brush component
formed by the method of Figures 6-8;
FIGURE lO is a perspective view sho~fing the array
of bristles passing through two spaced pairs of haul-off
belts suitable for the second and a tllird Form of the
invention;
FIGURE ll is an end view of an array oF bristles
after beads nf ma-terial have been e~truded centrally of
the array of bristles in accordance with the third
form of the invention; and
FIGURE 12 shows two brush components which result
after the array shown in Figure ll has been slit in two.
ReFerring to the drawings, and in par-ticular to
Figures 1-5, a plurali-ty of brush bristles Formed oF
synthetic resinous material of predeterrnined leng-th are
fed from a hopper (not shown) into a channel ~not shown)
so as to form an array of bristles l of uniform thickness
and den6ity as shown in Figure l. If necessary, the
edges of the bristles can be tamped so tlat they are all
in alignment. The bristles are then hauled out of the
channel and into the nip of a pair of endless haul-oFF
3D belts 3, 5, o~ known construction. The belts 3, 5 have
a width less-than the length of the bristles so that the
ends of the bristles project beyond the side eclges o~ the
belts as shown in Figure 2, and while still in the nip of
the haul-oFf belts 3, 5, a bead of synthetic resinous
material 7, e.~. ~ thermoplastic bead, is extruded onto the
two projecting ends oF the oristles using a split extrusion
die 9. Durin(~ pass-age throu~h the extruder, the side
edges of the arra-y are heated to a temperature su-fficient
6- ~L ~ f~
at least to soften the bristles, and prefe}ably to
a temperature suFficient to fuse them -together. '.~hile
still in this soft or molten state, the beads 7 are
extruded onto the eclges, ancJ if the beads are of the same
synthetic resinous material as -the bristles, they will
fuse completely with the bristles. It has been found
that best results are obtained by heating to fusion
temperature, otherwise the bristles act as a heat sink,
and a good bond between the beads 7 and bristles is not
achieved. The beads 7 -are subsequently cooled so as
.~ to lock the array of individual bristles into a permanent
fixed posi.tion and after passing out of the nip of the
belts 3, 5, thP bristle array with both edges held firm
by the thermoplastic beads is passed -th~ough a slitting
machine and the bristles. are cut centrally down the l~ngth
of the array as shown in Figure 4 to form two continuous
lengths oF brush component 13 tsee Figures 4 and 5).
In the alternative form of the invention shown in
Figures 6-9, an array of bristles is formed in the same
2û manner as described with reference to the preYious form
of the invention and the array is hauled fro~ the channel
by means of two s.paced pairs of haul-off belts 17, 19
(see Figure 10), so that just the two edges oF the array,
i.e. the ends of the bristles, are contacted by the belt
nips. Again, the array is passed throu~h an extruder,
and as before, is heated along the centre of the array,
whereupon a wide bead of synthetic resinous material 21
is extruded centrally on one face of the array and on the
opposite face a narrow bead 23 is extrucied (see Figure 6),
3~ both the beads preferably being of thermoplastic material
(preferably the same as that of the bristles). ~Ihile
the thermoplastic oeads and bristles are still molten, the
array of bristles is folded upon itself as shown in Figure
7 into a generally U-shaped form so that the wide bead
is on the outside and the narrow bead on the inside,
whereupon the folded array is passed through the nip of a
pair of Forming rollers 25, 27 so as to forn the two beads
into the shape shown in Figure 9. The beads are
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subsequently allo~ed to cool. EFf~ctively, the two
beads impregnate the bristles and/ar are fused with the
fused bristles and become a single bead 29 suitably
shaped to locate the subsequent brush componen~ 31 in a
suitable channel.
In the third farrn of the invention, the array of
bristles is Formed and hauled off from the feeder
channel in the same manner as for the second form of the
inven~ion and is passed into an extruder, heated and
equal volumes of synthetic resinous material 33 are
extruded onto the top and bottom surfaces of the array
; of bristles along the centre line of the bristles, as
shown in Figure 11, at a temperature and pressure
sufFicient to penetrate and impregnate and/or fuse with
the bristles in the array. After the extrusion operation,
the extrusions are allowed to cool, whereupon the bristle
array is slit centrally down the centre of the extrusions
33 using a slitting kniFe 11. It will thus be appreciated
! that the extrusions 33 are shaped and sized so that the
resultant lacking beads 35 are of sufficient height and
the correct shape to locate the thus Formeri brush cornponents
in a re-entrant holding `channel.
It will be appreciated that in all forrns of the
present invention, the shape of the extrusions can be
chosen for locating the brush componen-t in a suitable
locking ~roove, for example, on a brush body with a
handle or in a domestic appliance such as a vacuùm
cleaner, and that the required length of brush component
can be obtained-merely by cutting it off from the endless
length of component.
If desired, the brush component can be stren~thened
and be caused to conform to various shapes by insertin~
a length oF wire or other coated or uncoated strengthening
material, e.g. yarn, polymer rods9 strips or the like ~hich
could be resiliently deformable, into the extrusions.
Where the extrusions are down the side edges of the bristle
array,it ~Yould be a simple matter to insert a length of
wire internally oF the extrusion and in the-second form
of the invention the wire could be ?rovided io the bead
21 or in the bead 2~ or possibly in both beads. In
the third for~ of the invention it is envisayed that at
least two wires would be required suitably located so
that a-t least one wire was arranged in one of the brush
components and at least one was arranged in the other
brush coMponent after the sli~ting operation.
While extrusion has been described as -the rnethod
by which the bristle arrays are held together, it will
be appreciated that if the bristles are formed of a
thermosetting synthetic resinous material, tney could be
held together by fusing. In this instance a fusion head
could replace the extrusion head, and instead of extruding
strips along the length of the array of bristles, they
could be fused together. It is preferred that the
bristles are formed from polymer monclfilament, although
other materials could be used, includins natural bris~le.
Of course, the fusing technique (i.e. heating) can
be used in conjunction with ex-trusion.
In the above description with reference -to the
drawincJs, the bristles have been loosely advancecl by the
- haul-off belts. It is envisaged, however, that they could
be held together by knitting warps around pre-~elected
groups of bristles, con-tinuously. An equivalen~
product could be obtained by taking the zig zag formation
disclosed in our U.K. Pate nt No.1457074, cutting off the
loops down each side-edge, and feeding the resultant
product to the haul-off belts.
