Note: Descriptions are shown in the official language in which they were submitted.
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Method and Apparatus for the Manufacture of Brushware
and Brushware Manufactured according thereto
The invention relates to a method for the manufacture of brushware,
5 comprising a bristle carrier made from elastic material having at least one sub-
stantially cylindrical recess for receiving a bristle bundle, which has on its
fastening-side end a bristle-connecting thickened portion, whose cross section
is larger than the narrowest cross-section of the recess and which is positivelyinserted under pressure into the recess on the bristle carrier, the wall of the
10 recess on passing the thickened portion springing out elastically and springsback behind the thickened portion until engagement takes place with the
bristles of the bristle bundle. The invention also relates to an apparatus for
performing the method and to the brushware manufactured according thereto.
In the present context brushware is understood to mean all products, in
15 which bristle bundles or individual bristles are fastened to a carrier or support
having a random shape. These can be conventional brushes such as tooth
brushes, body brushes, cleaning brushes, scrubbers, brooms, abrading brushes,
polishing brushes, etc. The carrier or support can be a handle, grip or appliance
casing, as well as bands, strips, etc., or only preliminary products which are
20 subsequently inserted in a handle, grip, appliance, etc. or are interconnected
to form larger units. Bristle bundles are bundles having a random cross-section,e.g. tubular bundles, polygonal bundles, hollow bundles, bundle packs, etc. The
bristles are made from plastic and the thickened portion can be produced by
melting the bristle ends and cooling and optionally by after-shaping.
The aim with plastics brushes was to obviate the previously used
mechanical fastening method or the adhesion method. Thus, it is known (DE
845 933), to provide the bristle bundles with a thickened portion by melting
the bristles and to inject the bristle carrier material around said thickened
portion, so as to anchor the bristle bundle in extraction-proof manner in the
carrier. This injecting in of the bristle bundle has subsequently been improved
(DE 35 11 528, EP 142 885) .
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ln another technology the bristle carrier is provided with preshaped
recesses and either melted in the vicinity of the recess and/or the thickened
portion on the bristle bundle in a zone close to the surface and the bristle
bundle with the thickened portion is pressed into the recess (US 4 609 228,
5 US 4 637 660). Following insertion the bristle carrier melt flows round the
thickened portion and at the same time there can be a melting together of the
plastic components of the bristle bundle and the carrier.
Finally, a thermoelastic joining method is known (US 4 988 146), in
which the wall of the recess and/or the thickened portion on the bristle bundle
10 are heated in the zone close to the surface to temperatures below the meltingpoint and subsequentlythe bristle bundle with the thickened portion is inserted,accompanied by thermoelastic deformation. After cooling the bundle is firmly
anchored with the thickened portion in the carrier.
In all these cases heat must be supplied and then removed, which
15 always takes time, so that in these known methods the working cycles are
relatively long. In addition, the temperature must be very accurately controlled,
so as to avoid thermal damage, particularly embrittlement or thermal oxidation
of the polymers. In no case is it possible to prevent a deterioration to the
molecular structure of the bristles with their often very small diameter.
For special brushes, particularly hair brushes, it is known (DE 937 765)
to provide bag-like depressions on a plate-like, rubber-like carrier and to insert
in said depressions wire or plastic pins or also bristle bundles with a thickening
at the fastening-side end. On insertion the wall of the bag like depression
elastically gives way and springs behind the thickened portion until it engages
on the pin or bundle. Subsequently the plate is marginally fixed in a brush bodyand curved out, so that it springs through when h brush is in use.
The problem of the invention is to propose a method and an apparatus
for the manufacture of brushware and brushware manufactured according
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thereto, which allow an inexpensive manufacture with short working cycles,
whilst obtaining brushware with improved bristle bundle extraction resistance.
Based on the known method of DE 937 765, the problem is solved in
that the bristle bundle has its axis aligned with the axis of the recess in the
5 bristle carrier and is driven into the recess by the direct action of a force to the
thickened portion.
The force to be applied for driving in is decisively dependent on the
modulus of elasticity of the bristle carrier material and on how the thickened
portion and recess are geometrically dimensioned and matched to one another.
10 These parameters can be easily determined by a few tests, as a function of the
brushware type to be manufactured. Then, in trouble free manner, driving in
forces of the necessary magnitude can be produced and transferred to the
thickened portion on the bristle bundle, so that following driving in on the
bristle bundle an extraction resistance is obtained, which is close to that of
15 conventionally manufactured brushware. Preferably, the axes of the bristle
bundle and the recess are brought into alignment, however, a slight inclination
or offset is not detrimental as the thickened portion centers itself. Otherwise
the method is not only applicable with bristle bundles, but also with single
bristles as long as they have a thickened portion at their fastening ends.
The force for driving in the bristle bundle is preferably uniformly applied
to the projecting length of the thickened portion projecting circumferentially in
annular manner over the bristles of the bristle bundle.
If the bristle bundles are constructed as hollow bundles, in which the
bristles are arranged in annular manner, the thickened portion at least partly
also projects into the cross-section of the cavity, but can also terminate the
latter in plate-like manner. With such hollow bundles, according to the
invention the force for driving in the bristle bundles is applied to the thickened
portion within the cavity.
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lt is advantageous and known per se for the recess in the bristle carrier
to have an undercut. In this case the force for driving in the bristle bundle ismade to act on the thickened portion until the latter has reached the largest
cross-section of the recess behind the undercut.
As a rule a brushware article, e.g. a brush, has a plurality of bristle
bundles and the bristle carrier a corresponding number of recesses. The method
according to the invention offers the possibility of simultaneously driving all the
bristle bundles or groups of bundles into the recesses on the bristle carrier.
In addition to the force becoming effective on driving in the thickened
portion, a force can also be applied to the free ends of the bristle bundles
whereby the bundle preferably is clamped on its periphery to prevent the
bristles from buckling.
When increased demands are made on the extraction resistance, it is
appropriate to insert the elastic bristle carrier with the inserted bristle bundles
in a rigid support, accompanied by the clamping or bracing of the bristle carrier.
For performing the method, the invention is based on an apparatus with
a receptacle for the bristle carrier and a holder for the bristle bundle. According
to the invention, such an apparatus is characterized in that the holder has a
punch, whose leading front end acts on the thickened portion on the bristle
bundle is driven axially in the direction of the receptacle with the bristle carrier
and can be inserted in the recess up to the final positioning of the thickened
portion.
Thus, the punch passes into the recess together with the bristle bundle
and outwardly displaces the elastically resilient wall of the recess until the
thickened portion has reached its final position. Following the extension of thepunch the elastic wall of the recess springs back, fixes the thickened portion
and simultaneously embraces the bristles of the bundle, to the extent that they
are located within the bristle carrier.
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The punch can be constructed as a sleeve externally embracing the
bristle bundle and which acts with its annular front end against the projecting
length of the thickened portion projecting over the bristles of the bristle bundle.
Such a sleeve-like punch simultaneously guides the bristle bundle and applies
5 the lateral displacement forces to the elastic material of the bristle carrier.
Advantageously the sleeve has on its area acting on the projecting length of
the thickened portion an external cross-section, which is not larger than the
greatest cross-section of the thickened portion and then, accompanied by the
formation of a step, has a larger cross-section. The step forms a stop or
10 abutment cooperating with the bristle carrier sur face for the driving in depth
of the bristle bundle.
In the case of hollow bundles the punch has a bolt-like construction. It
engages in the hollow bundle and acts with its leading front end on the thick-
ened portion projecting over the internal diameter of the hollow bundle. If the
15 thickened portion is so constructed that it terminates in the downwards
direction the hollow bundle in a plate-like manner, the punch acts on the insideof the plate-like thickened portion.
In the case of an annular thickened portion, according to a preferred
embodiment the punch can have a smaller diameter part engaging in the
20 annular space of the thickened portion and the step formed on the punch as
a result of this acts at the time of driving in on the inside projecting length of
the annular thickened portion.
In conjunction with the method of the invention and the apparatus for
per forming it the bristle carriers are chosen from a material which is rubber like
25 at normal temperature and whose elasticity is so adjusted as a function of the
ratio of the cross-sections of the recess and thickened portion that after driving
the bundle into the recess, the thickened portion is positively held due to the
resilience of the bristle carrier material and the bristle bundle, over its length
located in the carrier, is closely embraced by the latter and in this way
30 bandaged, without significant cavities being left. The material for the carrier or
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its elasticity must be adjusted in such a way and the geometrical dimensions
of the recess and the thickened portion must be so matched to one another,
that the bristle bundle can be inserted with an acceptable force expenditure,
but at the same time an extraction resistance is achieved, which satisfies the
5 intended use of the brushware. Materials satisfying these conditions are natural
and artificial rubbers, as well as a number of known elastomers.
It is obvious that the manufacturing procedure for such brushware with
high bundle extraction resistance is much simpler than the hitherto used
thermo plastic or thermoelastic methods, because fastening can take place
10 under normal temperatures. This considerably reduces apparatus costs and in
particular much shorter cycle times are possible, which fall within the range ofmechanical fastening procedures. The further advantage is achieved compared
with the latter that there is no need for additional or unusual fastening means.
Brushware constructed according to the invention also has improved use
15 characteristics, in that the rubber-like nature of the carrier in many applications
offers advantages, e.g. there is a reduction in the injury risk in the case of
toothbrushes, cosmetic brushes, body brushes, etc. In the case of brushes,
brooms, etc. used for cleaning purposes, as well as technical and industrial
brushes the damage risk to other objects in the movement area of the brush
20 is reduced and favourable damping properties result from the elastomeric
behaviour, which is particularly advantageous with mechanically driven
brushes .
This obviates the hitherto necessary very complicated measures for
producing flexible brushes from otherwise rigid materials, such as is widely
25 described in the prior art (W0 92/17092, W0 92/17093, EP 504 893).
The invention also relates to brushware according to the preamble of
claim 15 characterized in that the bristle carrier is made from rubber-like
material with the inserted bristle bundles and whilst utilizing the elasticity is
placed in a corresponding recess of a less elastic to rigid carrier or support,
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which encloses and fixes in frame-like manner the elastomeric carrier. This
recess can optionally be undercut. The rigid support can form the brush grip
or handle.
The rubber-like nature of the carrier not only leads to the elasticity
5 thereof, but at the same time forms a damping mounting for the bristle bundle,so that the latter is movable axially and transversely to the axis to a limited
extent. Such an elasticity is in particular desired in toothbrushes. The mobility
of the bristle bundle can, in the latter construction, be assisted in that the
carrier has cavities on its side remote from the bristle bundle. If this carrier is
10 inserted in a rigid body, then the rubber-like material of the carrier can fall back
into these cavities when force is exerted on the bristles, so that, as a function
of the arrangement of the cavities, the bristle bundle can give way to a greateror lesser extent axially or transversely thereto.
Instead of this, the bristle carrier from the rubber-like material can at the
15 same time form a grip and have in the area of the latter a greater stiffness. In
this construction the bristle carrier and grip are constructed in one niece.
A greater stiffness in the grip area can be achieved by stiffening inserts
or envelopes, or by material restructuring, e.g. by foaming only in the grip area.
The necessary stiffness can also be ensured by larger cross-sections in the grip20 area.
According to a preferred development the recess on the bristle carrier is
undercut, the smallest cross-section of the recess being smaller than the
cross-section of the thickened portion on the bristle bundle.
In this construction the self-closure between the bristle bundle and the
25 carrier not only results from its rubber-like properties, but also is ensured by
the shaping of the recess, the rubber-like properties ensuring that the thickened
portion can pass through in trouble free manner the narrower cross section on
inserting the bristle bundle.
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ln another advantageous construction, the recess is provided on its
opening rim with a larger diameter than the external diameter of the bristle
bundle and then conically narrows in the depth. Thus, initially the driving in of
the bristle bundle is facilitated, in that the conical wall forms a type of insertion
5 bevel for the thickened portion and the punch. The bristle bundle also has thepossibility of giving way transversely to its axis, which is advantageous in
certain applications.
The recess can also be constructed as a through hole in the bristle
carrier, so that for the same axial alignment, the bristle bundle can be inserted
10 in the carrier from one or other side.
In each of the aforementioned brushwares the thickened portion on the
bristle bundle can be given a spherical, lenticular or discoidal construction orcan also taper conically in the axial direction of the bundle. The shaping is
chosen as a function of the necessary extraction resistance or the desired
15 mobility of the bundle transversely to its axis.
The invention is described in greater detail hereinafter relative to non
limitative embodiments and the attached drawings, wherein show:
Fig. 1 Three method stages on joining a bristle bundle to a bristle carrier
in a first embodiment of the apparatus.
Fig. 2 Several method stages on fixing another bundle type in a second
embodiment of the apparatus.
Fig. 3 A third embodiment for the fastening of the bristle bundle in two
method variants.
Fig. 4 Several method stages in fixing the bristle bundle in connection
with a further bristle carrier embodiment.
Fig. 5 A broken away longitudinal section in the vicinity of a toothbrush
head.
Fig. 6 A plan view for Fig. 5.
Fig. 7 A cross-section through a brush in another embodiment.
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Fig. 8 A plan view of a toothbrush head in a further variant.
For ease of understanding Figs. 1 to 4 only show a detail from a bristle
carrier 1 made from an elastomeric material in the vicinity of the fixing or
fastening point of a bristle bundle 2. The bristle bundle 2 comprises a plurality
5 of individual bristles 3, which are melted at their fastening-side end to a
thickened portion 4, the latter then being pressed flat, e.g. com pressed, so
that it acquires a lenticular shape and projects outwards over the actual bundle.
In the embodiment according to Figs. Ia to 1 c the bristle carrier 1 is providedwith a cylindrical blind hole 5, whose diameter is smaller than the external
10 diameter of the thickened portion 4.
The bristle bundle provided with the thickened portion 4 is driven or
bounced into the blind hole 5 in the direction of its axis. In this embodiment
use is made of an apparatus having a punch in the form of a sleeve 6 in which
the bristle bundle is inserted in closely held manner. At its front end, the sleeve
15 is drawn in by means of a step 7 to a smaller diameter portion 8. The external
diameter in the vicinity of the portion 8 is to be no larger than the external
diameter of the thickened portion. The end face 9 of the portion 8 of the sleeve6 (Fig. Ia) acts on the external diameter of the projecting length of the
thickened portion 4 projecting over the bristle bundle 2. Through the moving
20 down of the sleeve 6 with the bristle bundle 2 corresponding to the directional
arrows 10 in Fig. Ib, the thickened portion 4 is driven into the blind hole 5,
whose wall is displaced outwards due to the elastomeric nature of the bristle
carrier 1 until finally the thickened portion 4 strikes against the bottom of the
blind hole 5. The sleeve 6 is then pulled (Fig. 1 c), so that the wall of the blind
25 hole springs back in area 11 and the thickened portion 4 and the bristles of the
bundle 2 are closely secured over a certain length. The sleeve can be closed
at its remote end and with that closed face can exert an additional force to thefree end of the bristle bundle when driving the bundle in.
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ln the embodiment according to Fig.2 the bristle carrier 1 has a through
hole 12, which comprises a larger diameter portion 13 and a smaller diameter
portion 14. In this case a bristle bundle 2 in the form of a hollow bundle 15 isinserted. The hollow bundle 15 is melted at its fastening-side end to an in this5 case annular thickened portion 16 and the latter is pressed flat by
after-shaping. For inserting the hollow bundle 15 use is made of a bolt like
punch 17, which tapers over a step 18. The tapered portion 19 passes through
the free inner space of the annular thickened portion 16 (Fig. 2a). On moving
down the punch 17 in accordance with the directional arrows 20 in Fig. 2b,
10 firstly the tapered portion 19 and then the thickened portion 16 pass into the
two-step through hole 12. When the annular thickened portion 16 penetrates
the same the wall of the portion 13 having the larger internal diameter is
displaced outwards until the annular thickened portion 16 is located on the
step between the two portions 13 and 14 of the hole. The wall then springs
15 back in the vicinity of the larger portion 13 of the through hole 12, so that the
annular thickened portion 16 is anchored. Here again, in the vicinity of the
portion 13, the wall engages snugly from the outside on the bristle bundle and
then the punch 17 is pulled.
In Fig. 3 a bristle carrier 1 with a through hole 21 is given a constant
20 diameter over the bristle carrier thickness (Fig. 3a). In this embodiment thebristle bundle 2 with its thickened portion 4 at the front can be vibrated into
the bristle carrier 1 from above according to the directional
arrow 22 (Fig.3b) or with the bristles at the front according to the directionalarrow 23 (Fig. 3c).
In the embodiment according to Fig. 4 the bristle carrier 1 once again
has a two-step through hole 24, whose narrower portion 23 is located
upstream of the further portion 26 in the driving in direction. Once again a
bristle bundle 2 with the thickened portion 4 is vibrated in by means of a
sleeve 6 according to Fig.1. In this embodiment, at least in its portion 25, theblind hole 24 is narrower than the external diameter of the thickened portion
4, so that following insertion (Fig. 4b) and the return of the sleeve 6 (Fig. 4c),
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the thickened portion 4 is located in the further portion 26, whilst the wall ofthe portion 25 springs back and closely embraces the thickened portion on its
top zone and the bristle bundle in the vicinity of the portion 25. Therefore thebristle bundle is effectively anchored against tensile forces. To avoid a sliding
5 of the bristle bundle to the other side, in this case the bristle carrier 1 can be
inserted in a recess of a separately manufactured handle or the like.
In all the aforementioned embodiments the recess 5, 13, 21, 24 can
conically widen in the vicinity of the opening edge in order to facilitate the
driving in of the bundle. When using the brushes, the conical widening also
10 gives the bundles a possibility to more strongly give way transversely to their
axis than would be allowed by the elasticity of the carrier.
Fig. 5 shows the head 31 of a toothbrush 30 in section. The head 31
has on its bristle side a recess 32, in which is inserted an elastomeric material
bristle carrier 1 with the bristle bundles 2 fixed therein by driving in. The
15 bouncing in can take place according to one of the above-described method
variants. The recess 32 has a outline, which forms a somewhat smaller cross
section than the bristle carrier 1, so that the latter can also be fixed in the
bristle head 31 by driving in. Naturally the bristle carrier can also be fixed by
bonding, welding or anchoring in some other way on the brush head 31. Fig.
20 6 is a plan view of the bristle area of the brush head 31 according to Fig. 5.
Fig. 7 shows an embodiment in which the bristle carrier 1 is also
inserted in a frame-like grip, handle 33 or the like. The elastomeric bristle
carrier 1 has on its side remote from the bristles 2 cavities 34, so that the
bristle bundles 2 have an increased mobility in the axial direction, but also in25 any direction at right angles to the bristle axis, in that the elastomeric bristle
carrier moves back under pressure in the vicinity of the cavities 34.
In this way, e.g. a toothbrush according to Fig. 8 with the brush head
35 can be equipped with a bristle carrier 1, whose bristle bundles 2 in the
areas 36 have a different mobility from that in the areas 37, so that during use
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the bristles can better adapt to the surfaces to be cleaned and their different
contours. This can be assisted in that the recesses 5 in the bristle carrier 1
(e.g. Fig. 1 ) are conically outwardly widened in the vicinity of the opening rim,
so that at the same time an insertion bevel for the thickened portion or punch
5 is formed.
In place of the two-part construction, as illustrated in Figs. 5 and 8 by
a toothbrush, the handle 30 can also be made from the same material as the
bristle carrier 1 and is merely made stiffer by correspondingly larger cross
sections, by inserts or envelopes, or by material restructuring, e.g. by foaming.
