Information
-
Patent Grant
-
6457667
-
Patent Number
6,457,667
-
Date Filed
Tuesday, May 30, 200024 years ago
-
Date Issued
Tuesday, October 1, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Mansen; Michael R.
- Pham; Minh-Chau
Agents
-
CPC
-
US Classifications
Field of Search
US
- 242 4215
- 242 4216
- 242 4217
- 242 4206
- 242 1298
- 242 128
- 242 1562
-
International Classifications
-
Abstract
The present invention relates to an improved bead wire letoff assembly and method of operation that controls the tension of wire being pulled from a wire spool mounted to the bead wire letoff assembly. The improved wire letoff assembly can accurately control the rotational speed of the wire spool and incorporates a cam plate and tension arm linkage to control the braking force applied to the wire spool.
Description
TECHNICAL FIELD
The present invention relates to a method and apparatus for removing bead wire off from a wire spool with a bead making machine and more particularly to a method and apparatus for controlling the tension of the bead wire being fed off of the wire spool mounted in a bead wire letoff stand.
BACKGROUND OF THE INVENTION
The tire building industry has been improving the methods and apparatus for controlling the tension of a wire or wires being fed into a bead making machine used in the manufacture of tire beads. The current practice is to place a roll or spool of wire in a device, commonly called a bead wire letoff stand, that allows the wire to be pulled from the spool at a controlled tension over a wide range of spool speeds (line speeds). The letoff stand must also be capable of stopping a full spool of wire at the maximum line speed. The control of the wire tension and the stopping of the rotating spool are typically accomplished with a braking device. One important consideration is that the latter mentioned functions of the braking device must be accomplished without allowing the mass of the spool to overcome the braking force of the braking device. Failure to overcome the inertia of the rotating mass would result in the spool of wire continuing to unwind. If the wire continues to unwind from the spool while not being used in the bead making machine, the wire will typically jump off the wire guide pulleys and accumulate as a heap of wire next to the let off stand.
In one current bead wire letoff stand, a somewhat complex mechanical linkage, includes a tension arm and linkage arms. A friction brake, mechanically connected to the tension arm, can apply a braking force to the wire spool depending upon the location of the tension arm. The pivot points in the tension arm and the associated linkage arms are prone to wear. Once the mechanical parts begin to wear, the letoff stand cannot maintain control of the tension of the wire being unwound from the wire spool and the stopping or slowing of the rotating wire spool as quickly and accurately as before the parts were at least somewhat worn. The mechanical linkage is adjustable by an operator so that the wire tension of the letoff stand can be held relatively constant irrespective of the mechanical wear. However, when a series of letoff stands are used in conjunction with each other to feed a plurality of bead wires a single bead forming device, each of the letoff stands typically exerts a somewhat different tension on the wire being unwound, as compared with the tension of a different one of the letoff stands. This variation in feed tension effects the winding tension of the beads, causing the formed wire beads to vary in inside diameter by several thousandths of an inch. This can result in an adverse effect on the quality and uniformity of the tire beads. In a worst case scenario, the tension varies enough to cause a problem known as “splitout,” or uncontrolled separation of the bead ribbon in the bead making apparatus, causing expensive downtime of the assembly procedure while the wires are restrung. Another important limiting design consideration of the current letoff stand designs is that they are generally limited to a wire line speed of about 250 fpm (feet per minute) [76.2 mpm (meters per minute)] to about 300 fpm [91.44 mpm]. New manufacturing methods require a faster line speed of at least about 500 fpm [152.4 mpm].
Accordingly, there is a need in the tire building industry for a letoff stand design that can effectively control the line tension and provide for braking of the wire spool.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for controlling the tension of wire being pulled from a wire spool mounted on a bead wire letoff assembly and being as defined in one or more of the appended claims and, as such, having the capability of being constructed to accomplish one or more of the following subsidiary objects.
It is an object of the present invention to provide a method and apparatus for controlling the tension of wire being pulled from a wire spool mounted on a bead wire letoff assembly.
It is still a further object of the present invention to provide an improved bead wire letoff assembly that can accurately control full reels of wire at a line speed above about 300 fpm [91.44 mpm].
It is a yet further object of the present invention to provide an improved bead wire letoff assembly that incorporates a cam operated in accordance with the location of a tension arm to control air pressure to an air brake that applies a braking force to a spool.
Accordingly, there is disclosed a bead wire let-off assembly into which is mounted include a rotating wire spool having bead wire unwound therefrom. A brake system for applying a braking pressure to the spool is provided with a pressure regulator controlling the braking pressure applied by the brake system. A tension responsive control arm engages the bead wire and moves in response to changes in bead wire tension. The control arm is operationally connected to the pressure regulator so that the braking pressure applied by the brake system to the wire spool is a function of the position of the control arm.
According to the invention, the brake system has a first axle secured to and extending outward from the rotating wire spool, the first axle having a first centerline therethrough about which the spool rotates. A first gear wheel is attached to the first axle and a second axle being disposed in parallel relation to the first axle has a second gear wheel secured in engaging relationship with the first gear wheel. A pressure activated brake mechanism is provided to applying a braking force to the second axle in response to the receipt of pressurized air from the pressure regulator.
Further according to the invention, a third axle is disposed in parallel relationship to the first and second axles. The third axle has the tension responsive control arm and a cam plate secured thereto whereby movement of the control arm causes rotational movement of the cam plate. The pressure regulator has a piston rod engaging a cam surface of the cam plate whereby rotational movement of the cam plate causes an actuator piston rod to regulate the air pressure delivered from the pressure regulator to the air pressure brake. A bias force application device applies a biased force to urge the tension responsive control arm towards a position where the brake force is fully applied.
Also according to the invention, the method of controlling the unwinding of bead wire from a rotating spool includes the steps of: applying a braking pressure to the rotating spool with a brake system; regulating the braking pressure applied by the brake system with a pressure regulator; and controlling the braking pressure applied by the brake system as a function of the position of a tension responsive control arm engaging the bead wire and pivotably moving in response to a change in tension of the bead wire.
The method further includes the steps of: applying the braking pressure with a pressure activated brake mechanism that receives pressurized air from the pressure regulator to control the braking pressure applied by the brake system; pivoting the tension responsive control arm and a cam plate secured to cause rotational movement of the cam plate; engaging a cam surface of the cam plate with a piston rod extending from the pressure regulator whereby rotational movement of the cam plate causes an actuator piston rod to regulate the air pressure delivered from the pressure regulator to the pressure brake; and applying a force to urge the tension responsive control arm towards a position where the brake force is fully applied.
BRIEF DESCRIPTION OF THE DRAWINGS
The structure, operation, and advantages of the presently preferred embodiment of the invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying drawings, wherein:
FIG. 1
is a side view of the bead wire letoff assembly of the present invention;
FIG. 2
is a side view of the bead wire letoff assembly of
FIG. 1
with the side panel removed;
FIG. 3
is a top view of the bead letoff assembly shown in
FIG. 1
;
FIG. 4
is a left side view of the bead letoff stand through line
4
—
4
of
FIG. 1
; and
FIG. 5
is a left side view through line
5
—
5
of FIG.
1
.
DETAILED DESCRIPTION OF THE INVENTION
To best illustrate the present invention,
FIG. 1
shows a bead wire letoff stand
10
onto which a reel or spool (used interchangeably) of wire
12
can be rotatedly mounted. Because of the heavy weight of the spool, typically in the range of about 900 pounds (lbs.) [6523.2 kg] to about 1000 lbs.[7248 kg], the wire spool
12
can be mounted in the stand
10
by means such as rolling the spool
12
across a mounting plate
14
fixedly secured to a base plate
16
of the stand
10
. The side panels
17
of the stand
10
(only one illustrated in
FIG. 1
) cover portions of the letoff mechanism and are provided to protect the operator. Prior to mounting the spool
12
on letoff stand
10
, a large circular gear
18
, an
80
teeth gear being typical thereof, is mounted onto a spool axle
20
. The resulting axle and gear assembly
21
is slid into place through a center bore extending through the spool
12
so that the outer ends
20
a
,
20
b
of the spool axle
20
project outward from either side of the spool sides
12
a
and
12
b
, respectively. The gear
18
is bolted to threaded bore extension elements
27
, which are solidly attached to and project outward from spool side
12
a
, with threaded pins
22
. The gear
18
has a central collar section
18
a
through which the axle
20
extends and can be removably attached thereto. The gear
18
is disposed in spaced relationship to the side wall
12
a
of spool
12
and maintained in that position by any conventional manner, such as with spacers
25
, disposed about removable pins
22
and between the sidewall and the gear. While the gear and axle can move in conjunction with each other, it is also within the terms of the present invention for the gear
18
and the axle
20
to be arranged so that the gear can rotate independently about the axle's center of rotation through the centerline
26
of spool
12
. The outer end sections
20
a
and
20
b
of axle
20
are secured to a front and a rear support plate
29
a
and
29
b
, respectively, of the letoff stand
10
.
As best seen in
FIG. 5
, a circular gear
30
is mounted on an axle
32
which in turn is rotatably supported between two pillow block bearings
34
and
36
. At one end of the shaft
32
, a brake
38
is mounted. The brake
38
, includes a circular friction pad
40
, a circular metal braking plate
42
secured to the axle
32
, and a fluid or air actuated piston member (not shown) connected to a pressure line
43
in the fluid or air actuator
44
. In operation of the preferred embodiment, the air actuator
44
, in response to control pressure air received through air pressure line
43
from control pressure regulator
46
, as shown in
FIG. 4
, presses the friction pad
40
against the metal brake plate
42
. The metal brake plate
42
is turned by the rotation of axle
32
whenever the spool
12
is rotating and is slowed or stopped by the pressure of the brake pad
40
. The brake
38
can be secured to the wall
29
a
by the brake support base
41
. This brake, by the mechanism just described, applies a braking force to the axle
32
which slows down or controls its speed of rotation. As axle
32
turns more slowly, the speed of rotation of circular gear
30
causes a correspondingly slow speed of rotation of gear
18
which is in meshing relation with gear
30
. Accordingly, the speed of rotation of axle
20
, which is secured to the wire spool
12
, is reduced in relation to the pressure being outputted by control regulator
46
, as shown in FIG.
4
. As discussed in more detail below, control regulator
46
outputs a control air pressure into line
43
that is proportional to the position of arm
56
.
BRAKE CONTROL SYSTEM
An aspect of the present invention relates to the control system
48
for transmitting a force corresponding to the tension of the wire being unwound from spool
10
to one end of a control arm
56
which in turn regulates the control regulator
46
. The control system
48
includes a rotatable pulley
50
that is rotatably secured on an axle
52
. The control arm
56
is fixedly mounted at an opposite end to an axle
58
which is rotatably mounted through bushing
58
a
. At the opposite end of axle
58
, there is secured a cam plate
64
, as best seen in
FIGS. 2 and 4
. As the control arm
56
pivots about the center line
66
through axle
58
, as shown in
FIG. 4
, the cam plate
64
will also rotate about the axle so that the position of the cam surface
70
moves as discussed in more detail herein below.
Intermediate the ends of control arm
56
, that is between the axle
52
and the axle
58
, there is disposed a bias plate
72
having a central slot
74
extending therethrough, as shown in
FIGS. 2 and 4
. Along one side of the bias plate
72
, there is formed a triangular shaped groove
76
. The specific shape of the triangular groove
76
is not in and of itself an important feature of the present invention. However, the groove
76
does cooperate with a front triangular surface
78
of a block
80
having a cylindrical bore
82
and slidingly mounted on a tension rod
84
. The tension rod
84
is pivotedly secured at one end
86
to an axle
88
secured by a bushing, not shown. A coiled spring
92
is disposed about the tension rod
84
and can extend from one end of the rod, near or at the axle
88
, to a location in abutment with the block
80
. The spring
92
produces a bias force that causes the triangular face
78
of the moveable block
80
to bear against the triangular groove
76
of the bias plate
72
. As shown in
FIG. 2
, the tension rod
84
extends through the slot
74
of to the bias plate
72
so that the control arm
56
is free to move through an arc “x” of between about 40° and about 60°, and preferably at 45° to about 500 between two extreme positions. A bias force produced by the spring backed block
80
urges the control arm
56
towards a position closer to the location where wire
54
is being taken off or unwound from the wire spool
10
. Note that the rod
84
can pivot about the axle
88
to accommodate the range of movement by the control arm
56
.
In order to control the range or angle “x” of movement of control arm
56
between the end positions, a limit control structure is provided. The control structure
93
can be formed of a plate
94
and rodlike structures
96
a
,
96
b
spaced from plate
94
and providing a passageway through which the control arm
56
can freely pivot between the selected end positions. The end positions can be set for each particular application by providing moveable end plates
98
and
100
which are adjustably attached by conventional means to the rod structures
96
a
,
96
b
, respectively. The range of movement can be set by simply moving the end plates
98
and
100
closer or further from each other to achieve the movement arc of about 40° to about 60° and preferably about 45° to about 50°.
Referring to
FIGS. 2 and 4
, there is illustrated a letoff pulley
102
which is rotatedly mounted to a shaft
104
which in turn is secured to the wall
29
a
, as shown in
FIGS. 4 and 5
. The letoff pulley
102
, while rotating, preferably remains at a fixed location on the axle
104
.
Referring again to
FIG. 4
, the pressure control regulator
46
is mounted onto a plate
112
which in turn is secured to the side
29
a
of the letoff stand
10
. A reciprocating pin
114
projects out of the lower end of the pressure regulator
46
and is biased into contact with the cam surface
70
of cam
64
by a bias mechanism within the pressure regulator (not shown). Movement of the pin
114
causes a change in the air pressure in line
43
. The output air pressure from the air pressure control regulator
46
is transferred through the fluid actuator section
44
of brake
38
. In the preferred embodiment, the brake
38
is activated by air. However, it is within the scope of the present invention to use other fluids or gases to activate the brake
38
. In operation, the rotation of cam plate
64
in response to the pivoting of control arm
56
causes the rod
114
to reciprocate within the pressure regulator to control the air pressure being delivered from the pressure regulator to the brake
38
through line
43
.
OPERATION OF SYSTEM
After assembly
21
has been attached to a wire spool
12
a gear and axle, the wire spool is rolled into the bead wire letoff stand
10
and mounted by the ends
28
a
,
28
b
of the spool axle so that it is free to rotate about the center line
26
with gear
18
engaged with gear
30
, as best shown in FIG.
5
. Next, the bead wire
54
is threaded around the pulley
102
, in a counter-clockwise direction as shown in
FIG. 2
, and then around the pulley
50
.
Prior to the wire
54
being pulled from the pulley
50
, the control arm
56
will be abutted against the end plate
98
of the limit control structure
93
. Spring
92
, about the tension rod
84
, biases the block
80
against the bias plate
72
to maintain a bias force against the control arm
56
in the direction of the end position set by the end plate
98
. With the control arm in this position, the pin
114
of pressure regulator
46
bears against the cam surface
70
of cam
64
at a location which is furtherest from the center line
66
through axle
58
. This causes the introduction of the high pressure air to the brake
38
so that a brake force is applied to axle
32
which quickly slows down and finally stops rotation of the axle as next described. Gear plate
30
, which is mounted onto axle
32
is likewise prevented from rotating. Since gear
30
is in meshing relation with gear
18
, gear
18
slows down and then stops axle
20
and spool
12
from rotating. Then, as wire
54
is drawn from the pulley
50
, pulley
50
moves in a clockwise direction, as shown in
FIGS. 1 and 2
, which in turn causes the control arm
56
to pivot about axle
58
in a clockwise direction toward the limit plate
100
. This movement of control arm
56
is restrained by the bias of spring
92
pressing the block
80
against the bias plate
72
. Concurrent with the pivotable movement of control arm
56
, cam plate
64
rotates in the clockwise direction. The control regulator pin
114
, which is in abutting engagement with the cam surface
70
, moves closer to the axle
58
and causes the pressure regulator
46
to decrease the air pressure delivered through line
43
to brake
38
. Pressure regulator
46
is adjusted so that the wire spool
12
rotates about axle
20
in a controlled manner corresponding to the tension force exerted by the wire on the pulley
50
. As the control arm
56
pivots in the clockwise direction, the air pressure is reduced so that the speed of rotation of the wire spool
10
is increased.
As the speed of the wire
54
being pulled from the wire spool
12
is decreased, the control arm
56
moves quickly towards the position where the air pressure regulator
46
provides increased air pressure to the air brake
38
to immediately slow or stop the rotation of wire spool
10
. In effect, the control arm
56
reaches a substantially equilibrium position between the limit plates
98
and
100
of the limit control structure
92
and cycles back and forth slightly depending on the letoff speed and related tension of the wire
54
. This enables increased line speeds of between about 400 fpm [121.92 mpm] and about 475 fpm [144.58 mpm] and preferably up to about 600 fpm [182.88 mpm]. Nevertheless, if the line speed is suddenly slowed down or stopped, such as by a slowing down in the bead manufacturing device or a break in the wire, the braking force will be immediately applied to wire spool
12
. The braking force will cause the rotation speed of the wire spool
12
to slow down or almost immediately stop to prevent the wire from continuing to spool off of the wire spool
12
and typically become tangled on the plant floor which is both wasteful and time consuming for an operator to rethread the wire onto the pulleys.
It is apparent that there has been provided in accordance with this invention an improved bead wire letoff assembly and method of operation that satisfy the objects, means and advantages set forth hereinbefore. According to the invention, there is provided a method and apparatus for controlling the tension of wire being pulled from a wire spool mounted on a bead wire letoff assembly. The improved wire letoff assembly can accurately control full reels of wire at a line speed above about 500 fpm [152.4 mpm] and incorporates a cam plate operated in accordance with the location of a tension arm to control air pressure to an air brake that applies a braking force to the wire spool.
While the invention has been described in combination with embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing teachings. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.
Claims
- 1. A bead wire let-off assembly, characterized by:a brake system for applying a braking pressure to a rotating spool having bead wire unwound therefrom; a pressure regulator controlling the braking pressure applied by the brake system; a tension responsive control arm engaging the bead wire and pivotably movable in response to a change in tension of the bead wire to control the braking pressure applied by the brake system as a function of the position of the control arm; the brake system is further characterized by: a first axle secured to and extending outward from the rotating spool, the first axle having a first centerline therethrough about which the spool rotates; a first gear wheel attached to the first axle; a second axle having a second centerline therethrough, the second centerline being disposed in parallel relation to the first centerline; a second gear wheel secured to the second axle so that the first wheel gear is in engaging relationship with the second gear; and a pressure activated brake mechanism for applying a braking force to the second axle.
- 2. The bead wire let-off assembly of claim 1 characterized in that the pressure activated brake mechanism is an air pressure brake that receives pressurized air from the pressure regulator to control the braking pressure applied by the brake system.
- 3. The bead wire let-off assembly of claim 2 characterized in that a third axle is disposed in parallel relationship to the first and second axles, the third axle having the tension responsive control arm and a cam plate secured thereto whereby movement of the control arm causes rotational movement of the cam plate.
- 4. The bead wire let-off assembly of claim 3 characterized in that the pressure regulator has an actuator pin engaging a cam surface of the cam plate whereby rotational movement of the cam plate causes the actuator pin to regulate the air pressure delivered from the pressure regulator to the air pressure brake.
- 5. The bead wire let-off assembly of claim 4 further characterized by a bias force application device to apply a force to urge the tension responsive control arm towards a position where the brake force is fully applied.
- 6. The bead wire let-off assembly of claim 5 further characterized by a limit control structure to limit the pivotable movement of the tension responsive control arm between first and second positions.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/US98/00075 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO99/40011 |
8/12/1999 |
WO |
A |
US Referenced Citations (22)
Foreign Referenced Citations (2)
Number |
Date |
Country |
1361900 |
Apr 1964 |
FR |
2020854 |
Nov 1979 |
GB |