Information
-
Patent Grant
-
6666524
-
Patent Number
6,666,524
-
Date Filed
Wednesday, May 23, 200123 years ago
-
Date Issued
Tuesday, December 23, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Warden, Sr.; Robert J.
- Cole; Laura C
Agents
-
CPC
-
US Classifications
Field of Search
US
- 451 294
- 451 295
- 451 357
- 451 28
- 300 17
- 300 2
- 300 21
-
International Classifications
- A46D900
- A46D902
- B24B100
- B24B500
-
Abstract
Methods and devices are provided for end rounding filaments for use on brushes. The devices include an air driven planetary gear system rotating a sanding wheel through a varied elliptical path that attacks the filaments from all sides.
Description
TECHNICAL FIELD
This invention relates to methods and devices for end-rounding bristles and filaments that are used to make bristles.
BACKGROUND
Conventional toothbrushes generally include tufts of bristles mounted on the head of an oral brush handle. The working ends (i.e.—the end that contacts the teeth and gums) of the bristles generally must be smoothed to remove sharp edges that might cut or irritate the gums. This process is known as end-rounding.
In most end-rounding methods, the working ends of the bristles are contacted with a sanding disc. Generally, these sanding discs are rotated using an electric motor. The size and weight of an electric motor generally makes it impractical to move the end-rounder.
SUMMARY
The present invention features methods and devices for end-rounding bristles or continuous filaments that are used to make bristles.
In some implementations, the end-rounding device is movable into and out of contact with the filament ends, so that the filaments can be continuously fed in a single axial direction, without the bending and stress associated with moving the filaments into and out of contact with the end-rounder. Specifically, the end-rounder is moved into and out of position below the axial path of the ropes that eventually are cut into bristles.
The end-rounding device is air driven, light and has a low profile. The end-rounding device also has an ever-changing elliptical path, which attacks the bristles from all sides, producing a well-rounded bristle.
In one aspect, the invention features a device for end-rounding bristles including a sanding wheel mounted to a pneumatically driven support.
Some implementations include one or more of the following features. The pneumatically driven support includes a turbine. The pneumatically driven support includes a planetary drive mechanism that is driven by rotation of the turbine. The planetary drive mechanism includes a planet gear rotatably mounted on the pneumatically driven support and a fixed ring gear in engagement with the planet gear.
In another aspect, the invention features an end-rounding device that is less than about 2 inches in height. Preferably, the device weighs less than 5 pounds.
In another aspect, the invention features an end-rounding device having a planetary drive mechanism that is constructed to move the sanding wheel in an elliptical path.
Some implementations include one or more of the following features. The elliptical path is varied. The tooth ratio of the ring gear to the planet gear is about 2:1. The tooth ratio of the ring gear to the planet gear is slightly greater than 2:1. The pneumatically driven support is constructed to rotate at up to 5,000 revolutions per minute. The pneumatically driven support is constructed to rotate at up to 10,000 revolutions per minute. The sanding wheel is mounted on the pneumatically driven support so the center of the sanding wheel is within the pitch circle defined by the planet gear.
In another aspect, the invention features a sanding wheel and a planetary drive mechanism constructed to move the sanding wheel in an elliptical path. The planetary drive mechanism includes a planet carrier, a planet gear mounted on the planet carrier and a stationary ring gear wherein the planet gear engages the stationary ring gear and the planet carrier drives the planet gear. The tooth ratio of the stationary ring gear to the planet gear is slightly less than 2:1. The sanding wheel is mounted to the planet gear. The sanding wheel is mounted within a pitch circle defined by the planet gear. The planet carrier is pneumatically driven. The planet carrier is a turbine. The device is constructed to vary the direction of the elliptical path during rotation of the sanding wheel.
In a further aspect, the invention includes a feeding device constructed to advance a plurality of filaments through the machine in an axial direction and an end-rounding device constructed to be moved transversely relative to the axial direction, back and forth between a first position in which the end-rounding device is in contact with free ends of the filaments, and a second position in which the end-rounding device is not in contact with the free ends of the filaments.
In still another aspect, the invention features a method for end-rounding bristles including contacting the ends of bristles with an end-rounding device having a sanding wheel, the end-rounding device being constructed to move the sanding wheel in an elliptical path. Preferably, the end-rounding device includes a planetary drive mechanism and the planetary drive mechanism is pneumatically driven.
In another aspect, the invention features a method for end-rounding bristles including contacting ends of bristles with an end-rounding device including a sanding wheel and a pneumatically driven support for the sanding wheel.
Other features and advantages of the invention will be apparent from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
FIG. 1
is a perspective view of a toothbrush having bristle tufts that extend in different directions and at different angles.
FIG. 2
is a flow diagram of general steps followed by a tufting machine according to one embodiment of the invention.
FIGS. 3A and 3B
are flow diagrams of specific steps followed by the tufting machine.
FIG. 4
is a partial cut-away front view of a tufting machine according to one embodiment of the invention.
FIG. 5
is a side view of the tufting machine shown in FIG.
4
.
FIG. 6A
is a top view of a feeding device of the tufting machine shown in
FIG. 4
taken along line
6
A—
6
A, with the feeding device shown in its unbiased state.
FIG. 6B
is a cross-sectional view of the feeding device shown in
FIG. 6A
, taken along line
6
B—
6
B.
FIG. 6C
is an enlarged view of a portion of the feeding device shown in FIG.
6
B.
FIGS. 7A-7C
are views corresponding to
FIGS. 6A-6C
, with the feeding device biased to one side.
FIGS. 8A-8C
are views corresponding to
FIGS. 6A-6C
, with the feeding device biased to a side opposite that shown in
FIGS. 7A-7C
.
FIG. 9
is a top view of an end-rounding device according to one embodiment of the present invention.
FIG. 9A
is a perspective view of the end-rounding device of FIG.
9
.
FIG. 10
is a side cut-away view of the end-rounding device of FIG.
9
.
FIG. 11
is a top view of a stationary clamping device according to one embodiment of the present invention.
FIG. 12
is a top view of a moldbar according to one embodiment of the invention.
FIG. 13
is a perspective view of one toothbrush cavity of the moldbar of FIG.
12
.
FIG. 14
is a front view of the tufting machine shown in
FIG. 4
, showing movement of various elements of the tufting machine.
FIG. 15
is a front view of the tufting machine shown in
FIG. 4
, showing movement of various elements of the tufting machine.
FIG. 16
is a front view of the tufting machine shown in
FIG. 4
, showing movement of various elements of the tufting machine.
FIG. 17A
is a side cut-away view of a portion of the moldbar of
FIG. 12
showing the bristles being inserted.
FIG. 17B
is a side cut-away view of a portion of the moldbar of
FIG. 12
showing the bristles being inserted.
FIG. 18
is a perspective view of the moldbar of
FIG. 12
with bristles inserted.
FIG. 19
is a perspective view of the moldbar of
FIG. 18
with a blade engaged and the bristles cut.
FIG. 20
is a perspective view of the moldbar of
FIG. 19
with the blade disengaged and the bristles cut.
FIG. 21
is a side cut-away view of the moldbar of
FIG. 12
showing the bristles within the moldbar and a toe-tuft being inserted.
FIG. 22
is a side cut-away view of the moldbar of
FIG. 12
engaged with the rest of a toothbrush mold to form a toothbrush handle around the bristles.
FIG. 23
is a side cut-away view of the toothbrush of FIG.
1
.
FIGS. 24A and 24B
are side views of a rope of bristles looping on itself.
FIG. 25
is a perspective view of a tensioning device suitable for use in the tufting machine shown in FIG.
4
.
DETAILED DESCRIPTION
Preferred processes for feeding and end-rounding filaments to tuft an oral brush generally include the following steps, which will be discussed briefly now, and explained in further detail below. The processes described below are suitable for the manufacture of a toothbrush
10
having tufts
12
,
14
,
16
that are of different lengths and extend at different angles, e.g., as shown in FIG.
1
. The arrangement of the tufts will be referred to herein as the tuft geometry. The tufts are held in a moldbar
28
(FIGS.
12
and
13
), which has the desired tuft geometry and is used as a part of an injection-molding cavity to form a handle
18
around the tufts.
Generally referring to
FIGS. 2 and 4
, groups of filaments of bristle material are provided in a plurality of ropes
22
, each rope
22
corresponding in diameter and number of filaments to a tuft on a finished toothbrush. The free ends
24
of the ropes
22
enter a tufting machine
20
(step
110
, FIG.
2
). After the initial threading step, the ropes
22
are continuously fed from the spool
26
through the tufting machine
20
(step
111
, FIG.
2
). The free ends
24
of the ropes
22
are end-rounded (FIG.
15
and step
112
,
FIG. 2
) before being advanced into the moldbar
28
(FIG.
16
and step
114
, FIG.
2
). Once the free ends
24
of the ropes
22
are within the moldbar
28
, the bristles are cut to length (
FIGS. 18-19
and step
116
, FIG.
2
). Each moldbar
28
is configured to produce multiple toothbrushes (FIG.
12
), so this process is continued (step
117
,
FIG. 2
) until the entire moldbar
28
is full of bristles. Once the moldbar
28
has been filled with bristles, the moldbar
28
is advanced into an injection molding station where the handle
18
is formed around the bristles (FIG.
22
and step
118
, FIG.
2
).
Prior to introduction into the moldbar
28
, the free ends
24
of the filaments in ropes
22
are end-rounded within the tufting machine
20
by an end-rounding device
200
(FIG.
9
). The end-rounding device
200
of the present invention is low-profile and air driven, which allows the free ends
24
of the ropes
22
to be end-rounded within the tufting machine
20
. Conventional electric motor driven end-rounding devices would not easily fit within the tufting machine, and tend to be too heavy to move into and out of engagement with the free ends
24
of the ropes
22
quickly. The air-driven end-rounder
200
allows for a smaller machine, thereby saving valuable floor space.
Referring to
FIG. 4
, the ropes
22
are advanced through the tufting machine
20
, towards the moldbar
28
, by a feeding device
30
. Feeding device
30
is constructed to selectively advance the individual ropes
22
to different depths within the moldbar
28
corresponding to the tuft lengths of tufts
12
,
14
,
16
in
FIG. 1
, as will be discussed below. This selective advancement capability results in efficient and economical manufacture of toothbrushes
10
having tufts of different lengths. The tufting machine
20
can include any desired number of feeding devices
30
; two are shown in FIG.
4
. Multiple feeding devices
30
can be oriented at different angles relative to the vertical, as shown in
FIG. 4
, to allow the ropes
22
to be advanced into the moldbar
28
at opposing angles, resulting in a finished toothbrush
10
with tufts that extend at different angles, as shown in FIG.
1
. The selective advancement capability also results in a smaller tufting machine, which allows the process to occur closer to the moldbar thereby minimizing tuft damage or feeding problems.
The tufting machine
20
also includes a manifold
60
into which the ropes
22
pass after they have passed through the feeding devices
30
. The manifold
60
has guideways
51
that keep the ropes
22
on a path directly to the moldbar
28
. Within the manifold
60
is a stationary clamping device
59
, which works with the feeding devices
30
and the blade
70
, as will be described fully below. Also movably mounted on the manifold
60
is the end-rounding device
200
, which can be moved into and out of engagement with the free ends
24
of the ropes
22
.
Referring to
FIGS. 12
,
13
,
17
A and
17
B, the tufting machine
20
advances the free ends
24
of each of the ropes
22
into blind holes
82
,
84
,
86
in moldbar
28
. Each of the blind holes is shaped and sized to accept a single rope
22
in a close-fitting engagement. Each of the holes
82
,
84
,
86
is machined to a depth and at an angle that will provide the desired tuft geometry. Each hole
82
,
84
,
86
is filled by the tufting machine
20
, with the finished free end
24
of each rope
22
being inserted to the proper depth and at the proper angle.
After the ropes have been advanced fully into the moldbar
28
, i.e., after the free end
24
of each of the ropes
22
contacts the bottom
78
,
79
of each blind hole
82
,
84
,
86
of the moldbar
28
, the filaments are clamped by a stationary clamping device
59
and cut so that a portion of each filament extends above the top surface
76
of the moldbar
28
. This portion will extend into the mold cavity
80
(see FIG.
22
), and thus will be embedded in the injection molded toothbrush body
18
. The end rounded free ends
24
of the filaments will be the free or working ends of the bristles
12
,
14
,
16
in the finished toothbrush
10
(FIG.
1
). Each moldbar
28
is configured to produce multiple toothbrushes, as shown in FIG.
12
. Therefore, after cutting, the moldbar
28
is either indexed to the next set of unfilled blind holes
82
,
84
,
86
, or, if the moldbar
28
is full, removed and transferred directly to an injection-molding machine (not shown), where it is used to define part of the molding cavity
80
or to an intermediate step, such as fusing the filaments together to form an anchor.
The ropes
22
of filaments are not cut to tuft length until the end-rounded free ends
24
have been fully advanced into the moldbar
28
. Feeding continuous filaments, rather than cut tufts, into the moldbar
28
holes eliminates the sometimes problematic picking, tuft-transfer and moldbar-filling steps involved in filling a moldbar
28
with bristles, and as a result generally also reduces manufacturing problems.
The steps of this process, and the machine components used to perform each step, will now be discussed in further detail.
The Feeding Device
As discussed above, the feeding device
30
selectively clamps the ropes
22
that pass through the feeding device
30
, and advances the clamped ropes
22
towards the moldbar
28
.
Referring to
FIGS. 6A-6C
, the feeding device
30
includes a pneumatic cylinder
32
with a piston
34
. As shown by arrow A in
FIG. 4
, the feeding device
30
moves in a generally vertical direction relative to the frame
48
along a slide
38
, and is moved by a cam
36
. A motor
44
connected to the cam
36
by a leadscrew
40
and a leadscrew nut
42
drives the cam
36
.
Referring to
FIGS. 6A-6C
, the feeding device
30
has guideway holes
50
through which the ropes
22
pass. These guideway holes
50
pass through the feeding device
30
, including both the cylinder
32
and the piston
34
, and communicates with guideway holes
51
that extend through the manifold
60
. Thus, guideway holes
50
and
51
define a continuous pathway from the top of the tufting machine
20
to the moldbar
28
. The guideway holes
50
are shaped like the final shape of the tufts of bristles
12
,
14
that will be molded into the toothbrush handle
18
. Guideway holes
50
guide the ropes
22
through the tufting machine
20
, and provide selective clamping as will be described below.
The piston
34
of the feeding device
30
is capable of being biased to the center, as shown in
FIGS. 6A-6C
, to the left, as shown in
FIGS. 7A-7C
, or to the right, as shown in
FIGS. 8A-8C
. When the piston
34
is biased to the center, as shown in
FIGS. 6A-6C
, the guideway holes
50
are perfectly aligned and do not grip the ropes
22
. Certain guideway holes
52
within the piston
34
are elongated holes to allow selectivity when gripping the ropes
22
. When the piston
34
is biased to the left approximately 0.020 inches, as shown in
FIGS. 7A-7C
, the guideway holes
50
and elongated guideway holes
52
misalign at all locations and grip all the ropes
22
passing through. When the piston
34
is biased to the right approximately 0.020 inches, as shown in
FIGS. 8A-8C
, only the non-elongated guideway holes
50
misalign, allowing the feeding device
30
to grip only the ropes
22
that pass through the misaligned holes.
As will be discussed in detail below, the selectivity provided by elongated holes
52
allows the feeding device
30
to move certain ropes
22
further through the tufting machine
20
than others, thereby allowing tufts of varying lengths to be fed into the moldbar
28
using a single feeding device
30
. One advantage of a single feeding device
30
that selectively moves certain ropes
22
is compact size. Without the selectivity of the present feeding device
30
, two gripping devices would be needed to accomplish the same task, thereby increasing the size of the tufting machine
20
and the complexity of threading the ropes
22
through the tufting machine
20
. Further, the small size of feeding device
30
allows two feeding devices
30
to be mounted at different angles to each other (as shown in FIG.
4
), thereby facilitating easy manufacture of toothbrushes with tufts of bristles at opposing angles, such as the toothbrush
10
shown in FIG.
1
.
The Manifold
As described above, the manifold
60
is the part of the machine between the feeding devices
30
and the moldbar
28
that keeps the ropes
22
on a path towards the moldbar
28
and supports the end rounding device
200
and a stationary clamping device
59
.
Referring to
FIGS. 4 and 5
, the manifold
60
is below the feeding device
30
. Fitted into the manifold
60
is a stationary clamping device
59
, which is similar to the feeding device
30
in that it allows for selective gripping by using elongated holes. The stationary clamping device
59
consists of a plate
64
(
FIG. 11
) movably mounted to the manifold and a piston
62
connected to the plate
64
to move the plate
64
between three positions. The guideways
51
that run through the manifold
60
also run through the plate
64
, and are aligned precisely when the piston
62
is in a centered position. When pressure is applied to one end of the piston
62
, all guideways in the plate
64
misalign thereby clamping all the ropes
22
. When pressure is applied to the other end of the piston
62
, only non-elongated guideways in the plate
64
misalign, thereby clamping only selected ropes
22
.
The manifold
60
also supports an end-rounding device
200
. The end-rounding device
200
is described more fully below. The end-rounding device
200
can be moved into a position below the guideways
51
in the manifold
60
so the free ends
24
of the ropes
22
can be put into contact with the end-rounding device
200
(FIGS.
14
and
15
). The manifold
60
supports the end-rounding device
200
in T-slots (not shown) in the bottom of the manifold
66
, which allow the end-rounding device
200
to move along the bottom of the manifold
66
.
The End-Rounding Device
The end-rounding device
200
, shown in detail in
FIGS. 9
,
9
A and
10
, has a relatively low profile and is relatively light and compact, allowing the end-rounding device to be easily moved transversely into and out of engagement with the free ends of the filaments. Because the end-rounding device can be easily moved in this manner, during the entire tufting process the filaments need only be advanced axially, and do not need to be transported out of their plane of axial movement to engage the end-rounding device. Typically, the end-rounding device is less than 2 inches in height (dimension H in FIG.
10
), more preferably less than 1.5 inches, and weighs less than 5 pounds.
The end-rounding device also has a continually varying elliptical grinding path, described below, that allows the sanding surface of the end-rounding device to attack the free ends
24
of the individual filaments from all sides, resulting in uniform, high quality end-rounding with no damage to the individual filaments.
The end-rounding device
200
includes a sanding wheel
202
that is fixed to a planet gear
204
A that extends through a planet carrier
210
. A second planet gear
204
B also extends through the planet carrier
210
to balance the system. The planet gears
204
A,
204
B engage a stationary ring gear
208
mounted below the planet carrier, as described below, which causes the planet gears to rotate as the planet carrier rotates.
The rotation of the planet carrier
210
is driven by air, and the rotation of the planet carrier drives the rotation of the planet gear
204
A, due to the engagement of the planet gears with the stationary ring gear
208
. Thus, the sanding wheel
202
is entirely air driven, contributing to the low profile and compact size of the end-rounding device.
The planet carrier
210
is a turbine that drives the end-rounding device. The planet carrier
210
is rotated about its axis (arrow A,
FIG. 9
) by airflow against vanes
300
(
FIG. 9A
) which are arranged at spaced intervals around the periphery of the planet carrier. The vanes
300
are configured to allow compressed air to rotate the planet carrier
210
efficiently and at high rates of revolution, e.g., at least 5,000 rpm, more preferably at least 10,000 rpm. The planet carrier
210
sits within a radial/thrust bearing
214
, which includes an air manifold
216
to deliver the compressed air to the planet carrier
210
through openings
304
(FIG.
9
A).
As discussed above, when the planet carrier
210
rotates, the planet gears
204
A,
204
B engage stationary ring gear
208
. Stationary ring gear
208
is press-fit into the radial/thrust bearing
214
so that it does not move when engaged by the planet gears. As a result, this engagement causes the planet gears
204
A,
204
B to rotate about their axes in a direction (arrows B,
FIG. 9
) opposite to the direction of rotation of the planet carrier
210
. Stationary ring gear
208
and planet gears
204
A,
204
B together define a planetary drive mechanism
206
, which drives the sanding wheel
202
in a deviating elliptical orbit discussed below.
Because the planet carrier
210
acts as a drive mechanism and as an air bearing (replacing a ball bearing that would be required in a motor-driven end-rounding device), the end rounding device
200
requires relatively few parts, further contributing to its low profile and compact design. Moreover, the use of an air as a lubricant allows very high rates of revolution, as discussed above, without requiring liquid lubrication that could contaminate the filaments. Further, the planet carrier
210
provides a barrier between the sanding wheel
202
and the planetary drive mechanism
206
, thereby preventing any grinding dust from contaminating the planetary drive mechanism that could cause premature wear in the gears.
The preferred method of end-rounding the free ends of the filaments is to attack the filaments from all sides. However, if the number of teeth on the planet gear
204
were exactly half the number of teeth on the stationary ring gear
208
, any point on the pitch circle C of the planet gear would inscribe a straight line when the planet carrier is rotated, the line being a diameter of the stationary ring gear
208
. Each revolution of the planet carrier
210
would move the same point on the pitch circle continually along the same straight line. This is known as Cardanic Motion. This straight line would attack the filaments from only two sides. However, the path of the straight line may be deviated slightly by setting the tooth ratio of the stationary ring gear
208
to the planet gear
204
at slightly higher than 2:1, generally by a few teeth. With this tooth ratio, when planet carrier
210
is rotated, any point on the pitch circle C (
FIG. 9
) of the planet gear
204
will inscribe a straight line that slightly changes direction with every rotation of the planet gear
204
. This deviating straight line of a point on the sanding wheel allows the sanding wheel to attack the free ends of the filaments from all sides, resulting in uniform end-rounding.
If the sanding wheel
202
is mounted on the planet gear
204
so that the center of the sanding wheel lies on the pitch circle C, the sanding wheel comes to a momentary halt at the end of its stroke and tends to reverse direction along nearly the same path; i.e. the deviating straight line described above. This generally causes the filaments that are being sanded to be bent over in a cantilever fashion by the sanding wheel
202
during the “in” stroke, and may cause the filaments to be twisted out of plane when the sanding wheel
202
reverses direction. This action may damage the filaments and/or may not produce well-rounded ends
24
. Thus, it is preferred that the sanding wheel
202
be mounted with its center affixed to a point internal to the pitch circle C, so that the sanding wheel
202
will inscribe an ellipse rather than a straight line. When the sanding wheel
202
approaches its apogee it begins to rotate the filaments, achieving the opposite bend more or less gradually instead of suddenly. The slight change in direction of the inscribed line, as described above, will change the direction of the major diameter of the ellipse, resulting in a continual change in the direction of the overall elliptical path of the sanding wheel. Combining both the deviating straight line, which allows the filaments to be attacked from all sides, and the elliptical path, which prevents the filaments from bending in a cantilever fashion, provides well-rounded filaments.
It can be appreciated that the sanding wheel
202
may also be mounted such that its center point is outside the pitch circle, which will also allow an elliptical path to be achieved. Further, it should be understood that only certain points on the sanding wheel inscribe the deviating elliptical path. All other points on the sanding wheel with inscribe varying elliptical patterns, a small set that will degenerate into a straight line and a small set that will inscribe a circle. However, the majority inscribes some fashion of an elliptical pattern, and filaments end-rounded utilizing the described device are well rounded.
The Feeding Process
Referring to
FIGS. 4-5
, the ropes
22
are fed from spools
26
into the tufting machine
20
. The ropes
22
are threaded through the feeding device
30
and manifold
60
via guideway holes
50
(see
FIG. 6A
) and
51
, which generally keeps the ropes
22
on trajectory toward the moldbar
28
.
During the initial threading, the ropes
22
are fed into the tufting machine
20
to a point just above the bottom of the manifold
66
. Referring to
FIGS. 3A-3B
, the ropes
22
are advanced through the tufting machine
20
by the feeding device
30
, in cooperation with the stationary clamping device
59
. Describing the sequence starting with the ropes
22
just above the bottom of the manifold
66
, the feeding device
30
is biased to the left to clamp all the ropes
22
(step
120
, FIG.
3
A). The end-rounding device
200
is moved into position below the guideways
51
of the manifold
60
(FIG.
14
)(step
122
, FIG.
3
A). The feeding device
30
is advanced to bring the free ends
24
of the ropes
22
into contact with the sanding wheel
202
of the end-rounding device
200
(FIG.
15
)(step
124
, FIG.
3
A), and the stationary clamping device
59
is biased to clamp all the ropes
22
. Once the free ends
24
of the ropes
22
have been sufficiently rounded, the stationary clamping device
59
is biased to unclamp all the ropes
22
, the feeding device
30
withdraws the ropes
22
from the sanding wheel
202
to a point just above the bottom of the manifold
66
and the end-rounder
200
is moved back to its original position (step
126
, FIG.
3
A). The moldbar
28
is moved upward into engagement with the bottom of the manifold
66
(step
127
, FIG.
3
A).
The piston
34
of the feeding device
30
continues to be biased to clamp all the ropes
22
passing through (biased to the left as shown in FIGS.
7
A-
7
C), and the stationary clamping device
59
is biased to allow the ropes
22
to move freely. The feeding device
30
is moved downward, advancing the ropes
22
forward toward the moldbar
28
(FIG.
16
)(step
128
, FIG.
3
A). The distance D
1
moved corresponds to a point just above the bottom of the manifold
66
to the bottom
78
of the more shallow blind holes
82
,
84
of the moldbar
22
, which correspond to shorter tufts
12
(FIG.
1
), thereby advancing the free end
24
of the ropes
22
to the bottom
78
of those more shallow blind holes
82
,
84
in the moldbar
28
(FIG.
17
A).
The piston
64
of the stationary clamping device
59
is then biased in the opposite direction to clamp all the ropes
22
, and the piston
34
of the feeding device
30
is biased to the center (
FIGS. 6A-C
) to unclamp all the ropes
22
(step
130
, FIG.
3
A). The feeding device
30
then moves backwards along the ropes
22
a distance equal to the difference in length between the shorter bristles
12
and longer tufts
14
(
FIG. 1
) of the final product, i.e. distance D
2
in
FIG. 17A
(step
132
, FIG.
3
A). The stationary clamping device
59
prevents the ropes
22
from pulling out of the moldbar
28
by friction between the feeding device
30
and the ropes
22
as the feeding device
30
moves upward.
The piston
34
of the feeding device
30
is next biased to the right to selectively clamp the ropes
22
that will be longer bristles
14
(
FIG. 1
) in the final product (as shown in FIGS.
8
A-C), and the stationary clamping device
59
is biased to clamp the ropes
22
that have been advanced to the bottom of the shallow holes (step
134
, FIG.
3
A). The feeding device
30
then moves downward a distance D
2
, thereby advancing the rest of the ropes
22
to the bottom
79
of the deeper blind holes
86
in the moldbar
28
(FIG.
17
B)(step
136
, FIG.
3
A).
The stationary clamping device
59
then clamps all the ropes
22
and feeding devices
30
unclamp all the ropes
22
(step
138
, FIG.
3
A). The feeding devices
30
are then moved upward approximately 0.10 inches (step
140
, FIG.
3
B). The feeding devices
30
then clamp all the ropes
22
and the stationary clamping device
59
unclamps all the ropes
22
(step
142
FIG.
3
B). The feeding devices
30
and the moldbar
28
simultaneously move downward approximately 0.10 inches (step
144
, FIG.
3
B).
The stationary clamping device
59
is biased then to clamp all of the ropes
22
and the bristles are cut from the ropes
22
by a blade
70
, discussed in detail below (step
146
, FIG.
3
B). The blade
70
cuts the ropes
22
flush with the bottom of the manifold
66
. Next, the piston
34
of the feeding device
30
is biased to unclamp all the ropes
22
(
FIGS. 7A-C
) and the stationary clamping device
59
is biased to clamp all the ropes
22
. The feeding device
30
moves upwards along the ropes
22
to give the feeding devices
30
about ½ inch slack to feed the ropes
22
during the next cycle (FIG.
14
)(step
148
, FIG.
3
B). If the moldbar
28
is not completely full (step
150
, FIG.
3
B), the moldbar
28
is then advanced to allow a new, empty section to be aligned with the guideways
50
of the manifold
60
(step
152
, FIG.
3
B), and the process described above is repeated. If the moldbar
28
is completely full of bristles, the moldbar
28
is removed and a new moldbar is inserted into the tufting machine
20
(step
150
, FIG.
3
B).
It should be understood that the steps described above are the same for both feeding devices
30
, when two are used as shown in FIG.
4
and that the two feeding devices generally perform the steps simultaneously. Also, only a single stationary clamping device
59
is needed to cooperate with two feeding devices
30
.
Cutting the Filaments to Bristle Length
Referring to
FIGS. 18-20
, the ropes
22
pass out of the guideways
51
in the manifold
60
and into the moldbar
28
. A blade
70
is movably mounted on the bottom of the manifold
66
, and can move from a position out of engagement to a position into engagement with the ropes
22
that pass out of the guideways
51
in the manifold
60
.
The tufts
12
,
14
are cut from the ropes
22
by blade
70
. The moldbar
28
and the feeding devices
30
simultaneously move downward approximately 0.10 inches to allow the blade
70
to pass freely between the moldbar
28
and the bottom of the manifold
66
, as well as allowing the finished tufts in the moldbar
28
to protrude above the top surface
76
of the moldbar
28
. The stationary clamping device
59
is biased to clamp all the ropes
22
. The blade
70
engages, cutting the ropes
22
flush with the bottom of the manifold
66
, and then disengages, allowing the moldbar
28
to be indexed and new ropes
22
to be inserted. The ends protruding from the moldbar
28
are anchored into the toothbrush
10
when the toothbrush handle
18
is injection molded around them. The free ends
24
within the moldbar
28
become the working ends of the bristles in the finished toothbrush
10
(FIG.
1
).
Repeating the Tufting Process
After the tufts
12
,
14
,
16
have been cut to length, as discussed above, the moldbar
28
is indexed to align an empty section of the moldbar
28
with the guideways
51
in the manifold
60
. The above process is continued until all the moldbar
28
sections have been loaded with bristles. The moldbar
28
is then removed from the tufting machine
20
, and replaced with a new moldbar
28
.
The filled moldbar
28
may then be transferred to another filling station to receive more bristles (step
154
, FIG.
3
B), such as a toe-tuft
16
, as shown in FIG.
21
. Once the moldbar is completely filled, the moldbar
28
is transferred to an injection-molding machine (step
156
, FIG.
3
B), where it defines part of a mold cavity
80
, as shown in FIG.
22
. Before going to the injection-molding machine, the tufts could be fused together by a heating step, which also produces an anchor to be formed on the ends of the bristles, as is well known in the art. Resin is injected into the mold cavity
80
and a handle
18
is formed around the portions of tufts
12
,
14
,
16
that extend into the mold cavity
80
, anchoring the bristles firmly within the handle
18
(FIG.
23
)(step
158
, FIG.
3
B). The finished toothbrush
10
is then sent to a packaging station (step
160
, FIG.
3
B).
The Tensioning Device
Referring to
FIGS. 24A and 24B
, one problem may occur between the spools
26
and the tufting machine
20
. Since the ropes
22
are advanced at different lengths, the slack between the spools
26
and tufting machine
20
will vary from one rope
22
to the next and the variation will increase with each cycle of the tufting machine
20
. Eventually, the slack will cause a loop
88
in the ropes
22
(
FIG. 24A
) that will move out of plane and turn on itself (FIG.
24
B), eventually causing a snag or break. Putting each rope
22
through a separate tension device would typically be expensive and difficult to thread. Further, individual tension devices could have a problem compensating for the increasingly varied lengths.
To provide uniform tensioning, the present invention utilizes a tensioning device
90
, shown in FIG.
25
. The ropes
22
are threaded between two parallel plates
92
and
94
through guides
96
and
96
A. Guides
96
and
96
A are generally substantially colinear. The two parallel plates
92
,
94
are preferably made of a transparent material, such as glass or polycarbonate, to allow the operator to observe the ropes
22
within the tensioning device
90
. The parallel plates
92
,
94
are spaced so as to allow the ropes
22
to move towards the tufting machine
20
, while reducing the tendency of the ropes to move out of plane and flip on themselves. Generally, the spacing of the plates is from about 2 to 5 mm.
Side walls
98
and
98
A connect the two parallel plates
92
,
94
, and can either run the entire height of the parallel plates, as shown in
FIG. 25
, or for a portion of the height of the parallel plates
92
,
94
. Side walls
98
and
98
A are typically rubber gaskets, which both space and connect the parallel plates
92
,
94
. The guides
96
,
96
A are holes within the side walls
98
,
98
A, located generally toward the top of the parallel plates
92
,
94
.
A top wall
99
and a bottom wall
99
A also connect the parallel plates. The top wall
99
and bottom wall
99
A may be as long as the parallel plates
92
,
94
, as shown in
FIG. 25
, or a portion of the length. Top wall
99
and bottom wall
99
A are typically rubber gaskets, which both space and connect the parallel plates
92
,
94
. The top wall
99
will have one or a series of openings through which a fluid
95
, e.g., compressed air or water, is passed. The fluid
95
will pass over the ropes
22
, keeping tension on each individual rope
22
independent of the rope's length. The fluid
95
will then pass through openings (not shown) in the bottom wall
99
A, or around the bottom wall
99
A if the bottom wall is of a length less than the entire length of the parallel plates
92
,
94
. Generally, the fluid should flow in a direction substantially perpendicular to a line drawn between guides
96
and
96
A, preferably within ±5 degrees of perpendicular.
The tensioning device
90
is an easy and effective way to keep tension on each rope
22
and thereby prevent snagging. If water is used as the fluid
95
, the tensioning device can also serve the function of annealing the filaments if they have not yet been annealed during manufacturing, e.g., if the filaments are being fed directly from a spinneret or extruder rather than from a spool.
Other embodiments are within the scope of the following claims. For example, the methods and devices of the invention are also suitable to form other types of brushes, not just toothbrushes. Moreover, while the end-rounding device is described as being air driven, any type of compressed gas may be used. Also, the device described may be adapted to be used independent of a manufacturing machine. Accordingly, other embodiments are within the scope of the following claims.
Claims
- 1. A device for end-rounding bristles comprising a sanding wheel and a pneumatically-driven support for the sanding wheel, the pneumatically-driven support comprising:a circular bearing; a turbine; and a plurality of openings disposed about the inside periphery of the circular bearing, through which compressed air can be delivered to the turbine to provide an air bearing between the circular bearing and the turbine.
- 2. The device of claim 1 wherein the pneumatically-driven support further includes a planetary drive mechanism that is driven by rotation of the turbine.
- 3. The device of claim 2 wherein the planetary drive mechanism includes a planet gear comprising teeth rotatably mounted on the turbine, and, in engagement with the planet gear, a ring gear comprising teeth that is mounted so as to remain stationary when the turbine rotates.
- 4. The device of claim 3 wherein the tooth ratio of the ring gear to the planet gear is about 2:1.
- 5. The device of claim 3 wherein the tooth ratio of the ring gear to the planet gear is slightly greater than 2:1.
- 6. The device of claim 3 wherein the sanding wheel comprises a center and is mounted on the pneumatically-driven support so that the center of the sanding wheel is not on a pitch circle defined by the planet gear.
- 7. The device of claim 2 wherein the planetary drive mechanism is constructed to move the sanding wheel in a direction of an elliptical path.
- 8. The device of claim 7 wherein the planetary drive mechanism is constructed to vary the direction of the elliptical path.
- 9. The device of claim 1 wherein the device is less than about 2 inches in height.
- 10. The device of claim 1 wherein the device weighs less than about 5 pounds.
- 11. The device of claim 1 wherein the pneumatically-driven support is constructed to rotate at up to 5,000 rpm.
- 12. The device of claim 1 wherein the pneumatically-driven support is constructed to rotate at up to 10,000 rpm.
- 13. The device of claim 1, the turbine further comprising a periphery and a plurality of vanes positioned around the periphery.
- 14. A method of end-rounding bristles comprising contacting ends of the bristles with an end-rounding device comprising a sanding wheel and a pneumatically-driven support for the sanding wheel, the pneumatically-driven support comprising:a circular bearing; a turbine; and a plurality of openings disposed about the inside periphery of the circular bearing, through which compressed air can be delivered to the turbine to provide an air bearing between the circular bearing and the turbine.
- 15. The method of claim 14 wherein the pneumatically-driven support further includes a planetary drive mechanism that is driven is driven by rotation of the turbine.
- 16. The method of claim 15 wherein the planetary drive mechanism includes a planet gear comprising teeth rotatably mounted on the turbine, and in engagement with the planet gear, a ring gear comprising teeth that is mounted so as to remain stationary when the turbine rotates.
- 17. The method of claim 16 wherein the tooth ratio of the ring gear to the planet gear is about 2:1.
- 18. The method of claim 16 wherein the tooth ratio of the ring gear to the planet gear is slightly greater than 2:1.
- 19. The method of claim 16 wherein the sanding wheel comprises a center, and is is mounted on the pneumatically-driven support so that the center of the sanding wheel is not on a pitch circle defined by the planet gear.
- 20. The method of claim 15 wherein the planetary drive mechanism is constructed to move the sanding wheel in a direction of an elliptical path.
- 21. The method of claim 20 wherein the planetary drive mechanism is constructed to vary the direction of the elliptical path.
- 22. The method of claim 14 wherein the device is less than about 2 inches in height.
- 23. The method of claim 14 wherein the device weighs less than about 5 pounds.
- 24. The method of claim 14 wherein the pneumatically-driven support is constructed to rotate at up to 5,000 rpm.
- 25. The method of claim 14 wherein the pneumatically-driven support is constructed to rotate at up to 10,000 rpm.
- 26. The method of claim 14, the turbine further comprising a periphery and a plurality of vanes positioned around the periphery of the turbine.
- 27. The method of claim 26 wherein the turbine is rotated about its axis by providing airflow against the vanes.
US Referenced Citations (15)
Foreign Referenced Citations (4)
Number |
Date |
Country |
91 07 687.0 |
Aug 1991 |
DE |
195 25 808 |
Jan 1997 |
DE |
0740916 |
Jun 1996 |
EP |
1232140 |
Aug 1969 |
GB |