Brushing – scrubbing – and general cleaning – Implements – Brush or broom
Reexamination Certificate
1999-12-06
2002-03-05
Till, Terrence R. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Brush or broom
C015S205000, C015SDIG005
Reexamination Certificate
active
06351868
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of brush and bristle making, and more specifically, to a bristle sub-assembly having substantially parallel pairs of bristles that are attached to a base string. Bristle sub-assemblies of the type described herein are used in making bristle tufts in a variety of applications, especially toothbrushes.
DESCRIPTION OF THE RELATED ART
In my prior co-pending application, there is described a method of forming bristle sub-assemblies which, in brief, involves wrapping a polymeric monofilament around a mandrel and bonding the individual wraps to one or more base strings by applying thermal energy. As seen in
FIG. 1
, an apparatus
10
for making bristle sub-assemblies includes a rectangularly shaped mandrel
12
having a central passageway and open, opposite axial ends. Four base strings
14
,
16
,
18
and
20
are fed into one end of the mandrel from respective supply sources
22
,
24
,
26
, and
28
.
From the orientation of
FIG. 1
, the base strings are fed downwardly through the mandrel
12
and pass outwardly from the opposite end. Pulleys or wheels (not shown) are used to turn the base strings substantially 180° so that they can run along the respective four corners of the mandrel in the upward direction. While the base strings are running upwardly, a monofilament
30
, supplied from a supply
32
, is supplied at a controlled feed rate to a wrapping mechanism
34
. The wrapping mechanism
34
includes a motor
36
which drives a wrapper
38
, through which the monofilament
30
is fed, so that the monofilament is caused to wrap around the mandrel to form a plurality of wraps
40
. The wraps are transported upwardly by the upward movement of the base strings.
The wraps pass under heaters
42
, one being disposed at each of the four corners of the mandrel
12
(and only two of the four heaters being illustrated in FIG.
1
). As the result of application of thermal energy, such as by ultrasonic welding, the monofilament wraps
40
bond to the four base strings, either by melting the base strings or the monofilament, or both. After bonding, the wraps are passed over rotating cutting knives
44
, of which there are four in the embodiment of
FIG. 1
, thereby forming four bristle strings
46
, of which only two are partially shown and one is shown being taken up on a spool
48
.
FIG. 2
is an enlarged, end view of the bristle string
46
, revealing the base string
20
and two bristles
30
a
and
30
b
, constituting a bristle pair, which are connected to the base string
20
as a result of the thermoplastic melting of the monofilament
30
during the bonding step. The bristle string
46
would be a continuous length of base string with two, complementary rows of bristles, which as viewed in
FIG. 2
, would constitute a left row and a right row disposed at complementary angles to each other. Each bristle of one row would be paired, and substantially co-linear with, a bristle from the other row.
The angled orientation of the bristles results from the bonding step involved in the illustrated embodiment. However, variations of the manufacturing process of
FIG. 1
could result in a similar bristle string except with all the bristles being co-planar. An example is shown in
FIG. 3
, in which the bristle pair
30
a
′ and
30
b
′ of the bristle string
46
′ are not only co-linear, but co-planar as well.
While the bristle strings described above are advantageous in making toothbrushes, among other things, by cutting the bristle strings into lengths that become “bristle sub-assemblies” that can be used to form bristle tufts on a brush head, the bristle pairs of the bristle sub-assemblies may at times be preferred to be fixed in a parallel orientation with respect to each other, prior to securing the bristle sub-assemblies in a brush.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a bristle subassembly in which bristle pairs are fixed in an orientation where the bristles of each pair are oriented substantially parallel to each other.
Another object of the present invention is to provide an apparatus for forming bristle sub-assemblies in which the bristles of each bristle pair are fixed in a substantially parallel orientation with respect to each other.
Still another object of the present invention is to provide a method of forming bristle sub-assemblies in which the bristles of each bristle pair are fixed in a substantially parallel orientation with respect to each other.
Yet another object of the present invention is to provide a method of changing the directional orientation of monofilament bristles by heating to a temperature that is high enough to relieve the spring forces that are generated by bending the bristles to the new direction of orientation, yet low enough to avoid causing the molecular structure of the polymeric monofilament bristle material to change significantly. Partial melting at the interface between the bristles and base string is preferred to provide additional bonding between the bristles and base string.
These and other objects are met by providing a bristle sub-assembly which includes a base string, a first row of bristles connected to and extending radially outwardly from the base string, and a second row of bristles connected to and extending radially outwardly from the base string, wherein the first and second rows of bristles are substantially parallel to each other.
In another aspect of the invention, a method of making bristle sub-assemblies includes the steps of forming a bristle string having first and second rows of bristles extending outwardly from a base string, wherein the first and second rows of bristles are disposed in a first orientation with respect to each other, bending the bristles of at least one of the first and second rows of bristles to achieve a second orientation with respect to each other, thereby developing a spring force in the bristles that tends to restore the bristles to the first orientation, heating the bent ones of the bristles to a temperature sufficient to at least relax the spring force while maintaining the bristles in the second orientation and preferably add further bond area between the bristles and base string, and cooling the heated bristles so that the bristles maintain the second orientation.
In another aspect of the present invention, an apparatus for forming bristles sub-assemblies using as a feed material a bristle string having first and second rows of bristles connected to a base string, the first and second rows being in a first orientation relative to each other, wherein the apparatus includes means for bending the bristles of at least one of the first and second rows of bristles to achieve a second orientation of the bristle rows relative to each other, thereby developing a spring force in the bent bristles that biases the bent bristles towards the first orientation, means for heating the bristles bent in the bending step for a time and temperature sufficient to at least relax the spring force and preferably add further bond area between the bristles and base string, and means for cooling the heated bristles so that the bristles maintain the second orientation.
These and other objects of the invention will become more apparent from the following detailed description when taken in conjunction with the illustrative embodiments in the accompanying drawings.
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patent:
Brown Robert Maurice
Edwards Mark Stephen
Reed, III Winship Stinson
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