Note: Descriptions are shown in the official language in which they were submitted.
~786~
PROCE S FOR PRODUCING A TOOTHBRUSH AND
A TOOTHBRUSH BLANK FOR USE IN THE PROCESS
. .
The present invention relates to a process for
producing a toothbrush having a toothbrush head which is
provided with two bristle-supporting head portions.
Tooth brushes are known which have a first and a
second bristle-supporting head portion, which permit two
or more surfaces (outside, inside and masticating surfaces)
on a tooth in a series of teeth to be simultaneously
brushed. From French Patent Specification 1,230,365 it is
known to allow the bristle end planes to form an angle of
between 40 and 80. In Austrian Patent Specification
352,260 bristle end planes are proposed and illustrated
which form an angle substantially below 40. In United
States Patent Specification 4,115,894 several different
designs of toothbrush heads are proposed with different
angles for the head portions and with different angles for
the bristle end planes. In order to achieve the best
possible effect of brushing teeth with two obliquely
impac~ing groups of bristles provision has been made for
the bristles in each group to have the shortest bristle
innermost and the longest bristle outermost, reckoned from
the point of the bristle end planes impacting in V form.
~owever such a bristle design involves significant
manufacturing problems, since it has been difficult with
simple means and in a simple way to cut and polish the
bristle end plane of the two head portions simultaneously.
As a consequence of these manufacturing problems tooth~
brushes of the aEorementioned kind, even if they exhibit
significantly useful advantages, have not been competitive
from a price point of view relative to conventional
toothbrushes having a simple toothbrush head.
According to United States Patent Specification
4,449,266 it has been proposed to install the bristles in
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the two head ~ortions, while these are present in a flush
position to each other, after which the bristles - while
the head portions still occupy the same mutually flush
posit;on - are cut and polished and the head portions are
finally bent into a finished position. The problem with
such a mode of manufacture is that the bristle end planes
are cut and polished at an angle relative to each other.
Both the cutting equipment and the polishing equipment
must necessarily be of complicated design if one is to be
able to efEect the cutting operation and the polishing
operation in an accurate manner. Special problems involve
the polishing device being ma;nly able to rotate in a
speciEic position without substantial sldeways movement,
as is otherwise customary in the polishing of the bristle
end surface of the toothbrush. The toothbrush materials
must thereby be worked singly to a large extent.
With the present invention the aim is to avoid the
aforementioned problems, conventional cutting equipment
and polishing equipment being able to be employed
according to the invention and this equipment being able
to be moved in a conventional manner in one and the same
plane along the bristle end planes. In this way there is
the possibility of simultaneously finishing a large group
of toothbrush materials with associated bristles in a
common cutting operation and therea~ter in a common
polishing operation, in a conventional manner.
The process according to the invention is characterized
in that the bristles, after they are installed in their
respective head portions approximately at right angles (80-
100) to the main plane of the head portion, are cut andpolished at the ends jointly in a position where the head
portions form a convex arc or where the main planes of the
head portions form an angle d greater than 180 with each
other, after which the head portions are bent into a
concavely curved contour or into a position where the main
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planes of the head portions exten~ at an angle a to each
other.
~ y providing according to the i~vention a convex arc
or a "ne~ative" bending angle for the head portion, wh;le
cutting and polishing is effected, there is the possib;lity
of utilising conventional equipment for mass production in
a simple and uncomp~icated manner, so that there is
achieved a precisely defined cutting and polislling having
a high degree of quality on -the two groups of bristles of
the toothbrush material, which thereafter are bent towards
each other into a finished condition.
In order to ensure an accurate establishment of the
intended angle between the bristle end planes the bending
operation can be controlled to finished position with the
aid of simple means. In this connection it is preferrd
that the process according the invention is characterized
by using a toothbrush material which, at any rate at the
toothbrush head and if desired over the whole length of
the toothbrush material, is provided with one or more
mutually parallel, hinge-forming attentuation line(s),
formed by V-shaped grooves, the side surfaces of the
V-shaped groove after bending into the position of Einished
design form support abutments against each other and the
side surfaces in the position of finished desi~n being
glued or welded into permanent connection with each other.
The invention also relates to a toothbrush produced by
the process according to the invention, where the head of
the toothbrush is provided with mutually angled head
portions having rows of bristle groups directed obliquely
towards each other.
The toothbrush is characterised in that outer edges of
the toothbrush head converge in a direction forwards
towards the longitudinal central plane of the toothbrush,
and that the groups of bristles are arranged in equivalent
forward]y converging rows.
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A toothbrush is preferrea, where the groups of
brist]es at the inner front edge portion of the toothbrush
head are sign;ficantly shorter than the groups of bristles
at the outer rear edge portion of the toothbrush head.
The toothbrush is characterized in that a smaller
number of groups of bristles are arranged at the front
edge of each of the head portions of the toothbrush head
than at the rear edge of said head portions, and that
between inner edges of the head portions facing towards
each other there is cut out a forwardly opening V-shaped
groove, while correspondingly between inner rows of groups
of bristles o~ the head portions there is fashioned a
similar forwardly opening V-shaped groove at outer portions
of the bristles, at least between the groups of bristles
at front inner edges of the head portions.
Further ~eatures of the invention will be evident from
the following description having regard to the accompanying
drawings, in which:
Fig. 1-3 show in section a preliminary operation known
per se for installing bristles in two head portions of a
toothbrush blank.
Fig. 4 and 5 show the step of heating and a first
bending with a "negative" angle.
Fig. 6 and 7 show respectively the cutting operation
and the polishing operation with the head portions bent in
a "negative" angle.
Fig. 8 shows the head portions with associated brlstles
in a finished condition.
Fig. 9 shows a toothbrush blank according to the
invention illustrated from the back side.
Fig. 10 shows a toothbrush blank according to the
invention according to an alternative construction,
illustrated from the back side, correspondingly as in Fig. 9.
Fig. 11-~8 show in section production steps as shown
correspondingly in Fig~ 1-8 and based on a toothbrush blank
in accordance with Fig. 10.
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-- 5
In Fi~, 1 and 9 there are s~own two head portions 20
and 21 which are supported by a common handle 22 ~Fig. 9)~
and which together constitute a toothbrush blank. The head
portions 20 and 21 have the main planes as indicated by
chain lines 20a and 21a extending in alignment with each
other, that is to say they form an intermediate angle of
180 with each other.
In Fig. 2 the head portions 20 and 21 are shown after
they have heen fashioned with a series of bores or with
precast holes 23, and in Fig. 3 there are shown fastened-
in groups of bristles 24 recei~ed in the bores or the holes
~3 in the head portions 20 and 21.
In Fig. 4 the head part of the toothbrush blank is
subjected to heating shown by arrows ~5a locally along an
attentuation line 25 (Fig, 9) as indicated by a first
obtuser U-shaped cavity on the under side and a certain,
V-shaped cavity on ~he upper side of the transition
portion between the head portions 20 and 21.
In Fig. 5 the main plane 20a and 21a of the head
portions are bent to an intermediate "negative" angle d of
210. In Fig. 6 a cutting operation is shown illustrated
by a broken straight line 26 which shows that all the
bristles are cut with a common cut in one and the same
plane. Correspondingly there is shown schematically in
Fig. 7 a polishing operation illustrated by arrows 27, the
polishing equipment being able to be moved in a pattern of
movement parallel to the line 26 on Fig. 6. After the
polishing operation is effected, a new heating of the
hinge-orming narrowed transition portion between the head
portions 20, 21 is undertaken, after which the head
portions 20, 21 are pivoted back an angle d - a = 110 and
the main planes 20a and 21a of the head portions assume an
intermediate angle a equal to 100. This angle can be
guaranteed in an accurately established manner by allowing
the side suraces along the V-shaped groove of the
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attentuation line 25 to form a supporting abutment against
each other. Finally the head portions 20, 21 are connected
in rigid combination with each other in that said side
surfaces are glued, welded or jointed together in another
manner into a permanent and rigid union with each other.
In the position which is shown in Fig. 8 the bristles in
the first head portion 20 and the bristles in the second
head portion 21 assume an angle b = a relative to each
other, that is to say an angle b = 100. As a consequence
of the cutting to the "negative" angle d as shown in Fig.
5, that is to sa~ an angle d = 210, the bristle end
planes 20b and 21b of the bristles of the two head
portions 20 and 21 will form an angle c with each other,
chat is to say an angle c = 75.
Instead of effecting the bending from the position of
Fig. 4 to the position of Fig. 5 the brush heads can if
desired be produced in the position which is illustratecl
in Fig. 5, the bristles being able to be installed directly
into the brush head in the position shown in Fig. 5.
In Fig. 10 there is shown a toothbrush blank 30-33
consisting of a first head ~ortion 30 and a second head
portion 31 together with an intermediate head portion 32
which forms a planar extension of the handle 33.
~s shown in Fig. 10 and 11, each oE the head portions
30r 31 is connected to the intermediate head portion 32
via narrowed transition portions along attentuation lines
34 and 35 shown in the form of a V-shaped groove on one
side of the toothbrush blank. The side surfaces which
define said grooves form in a manner corresponding to that
shown in Fig. 8 stop-forming support abutments against
each other and cooperating joint surfaces between the head
portions, such as illustrated in Fig. 18, the production
taking place in Fig. 11-18 in an equivalent manner to that
shown and described in connection with Fi~ 8 according
to the first embodiment.
1~78G~;4
- 7
In ~he i]lustrated embodimen~s there are shown head
parts which are adapted to be angled with narrow angles
relative to each other along one or two hinge-Eorming
attentuation lines. If desired two or three such
attentuation lines can be emp]oyed. By employing said
attentuation lines short heating times can be employed, at
the same time as reliable control of the bending operation
can be obtained~ Alternatively one can effect, instead of
narrow angled bemds, bending from a convex to a concave
arcuate shape, by undertaking heating of the whole of the
head parts and fashioning the latter by ~eans of an extra
moulding surface or extra moulding means.
By employing the arcuate ~shape of the head part there
is the possibility of fashioning the head portion in an
easy manner into different variants as required, that is
to say with different shapes of the bristles in one and
the same group or with different shapes of the groups of
bristles.
While there is shown herein only two head portions
with their respective group of brist]es three or more head
parts can be alternatively employed, each with its
respective group of bristle~s. In the construction which
is illustrated in Fig. 10, 18 the central main part can
fox example be provided with a separate group of bristles
which can be received between the groups of bristles of
the two remaining head parts.
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