Winding – tensioning – or guiding – Tension control or brake – Supply controlled
Reexamination Certificate
1999-03-30
2001-11-13
Nguyen, John Q. (Department: 3653)
Winding, tensioning, or guiding
Tension control or brake
Supply controlled
Reexamination Certificate
active
06315234
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for unwinding a wire material from a reel, spool or the like under constant tension.
2. Description of Related Art
In
FIG. 1
is shown an embodiment of the conventional apparatus for unwinding a wire material under constant tension, in which a reel
20
winding a wire material
22
is placed on a spindle shaft
1
by inserting a support portion
2
of the shaft
1
into a hole
21
of the reel
20
. The wire material
22
is unwound from the reel
20
through fixed rolls
10
,
11
and a dancer roll
6
as shown by a phantom line. The dancer roll
6
is placed on an end of a rotatably arranged dancer arm
7
. A cylindrical portion
13
is coaxially arranged on the dancer arm
7
with respect to the rotating axis thereof. A brake band
4
is connected at its one end to the dancer arm
7
and fixed at the other end to a fixed portion
12
through contacting with the cylindrical portion
13
and a braking face
3
.
The dancer arm
7
is energized by a spring
8
fixed at its one end to a spring fixed portion
14
in a direction shown by an arrow X or in a direction of increasing a tension of the brake band
4
to increase a contact pressure to the braking face
3
. On the other hand, the dancer arm
7
is subjected to a rotating force by the tension of the wire material
22
through the dancer roll
6
in a direction shown by an arrow Y or in a direction of decreasing the tension of the brake band
4
to decrease the contact pressure to the braking face
3
. Thus, a braking force to the rotation of the spindle shaft
1
is controlled by a balance between the rotating force and the energizing force through the spring
8
.
That is, when the tension of the wire material
22
decreases during the unwinding of the wire material
22
, the dancer arm
7
rotates in the direction of arrow X and hence the tension of the bake band
4
and the contact pressure to the braking face
3
are increased to increase the tension of the wire material
22
. On the other hand, when the tension of the wire material
22
increases, the dancer arm
7
rotates in the direction of arrow Y and hence the tension of the bake band
4
and the contact pressure to the braking face
3
are decreased to decrease the tension of the wire material
22
.
In the conventional apparatus, therefore, it is desired to maintain the unwinding tension of the wire material at an approximately constant value by controlling the change of tension in the wire material to be unwound through the above construction and function.
However, when the dancer arm
7
rotates in the direction of arrow Y to decrease the tension of the brake band
4
, there is caused a problem that the looseness of the brake band
4
is caused and the control of the unwinding tension is not conducted smoothly. Particularly, this problem is apt to be caused when the tension of the brake band
4
is set to a relatively low value for unwinding the wire material under a low tension.
In
FIG. 1
, a phantom line W
1
shows a state of loosing the brake band
4
to form a curved deformation in the vicinity of the contact portion with the braking face
3
. As such a curved deformation is created, the contact area to the braking face
3
decreases to excessively decrease the braking force and hence there is caused a problem that the tension change of the wire material
22
becomes large. Also as the braking force excessively decreases, the tension of the brake band
4
rapidly increases to increase the tension of the wire material
22
and hence there is caused a problem that breakage or hunting phenomenon of the wire material occurs.
On the other hand, when the brake band
4
is curvedly deformed in the vicinity of a connected portion to the dancer arm
7
as shown by a phantom line W
2
, the brake band
4
rises to the cylindrical portion
13
and it is difficult to reflect the movement of the dancer arm
7
to the change of the braking force and hence the tension of the wire material
22
becomes not smoothly controlled.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to solve the afore-mentioned problems in the conventional unwinding apparatus and to provide an apparatus for unwinding a wire material capable of smoothly controlling the unwinding tension of the wire material even if the tension of the brake band decreases and always unwinding the wire material under a stable tension.
According to the invention, there is the provision of an apparatus for unwinding a wire material under constant tension, which comprises a braking face (
3
) rotating together with a reel wound with a wire material, a brake band (
4
) contacting with the braking face (
3
) and a brake control means connected to an end of the brake band (
4
) for controlling a tension of the brake band (
4
) to control a braking force, characterized by providing a deformation control means (
5
) for restricting deformation in at least a part of the brake band (
4
).
In a preferable embodiment of the invention, the deformation control means (
5
) is arranged at a position near to a contact starting point of the brake band (
4
) to the braking face (
3
) or a position near to a connected portion of the brake band (
4
) to the brake control means or at both positions in a region ranging from the brake control means to the braking face (
3
).
In another preferable embodiment of the invention, the brake control means comprises a dancer arm (
7
) and a brake energizing means (
9
) for energizing the dancer arm (
7
) in a direction of raising a contact pressure between the braking face (
3
) and the brake band (
4
) and the dancer arm (
7
) is provided with a dancer roll (
6
) and a cylindrical portion (
13
) coaxially arranged with respect to a rotating axis of the roll (
6
). In this case, the brake band (
4
) is connected at its one end to the dancer arm (
7
) and arrived to the braking face (
3
) through the cylindrical portion (
13
) and the deformation control means (
5
) is arranged so as to restrict deformation of a portion of the brake band (
4
) contacting with the cylindrical portion (
13
).
In the unwinding apparatus for the wire material under constant tension according to the invention, the change of the unwinding tension can be controlled even if the tension of the brake band (
4
) is set to a relatively low value for unwinding the wire material under a low tension, so that a brake adjusting means for adjusting a contact pressure between the brake band (
4
) and the braking face (
3
) can be arranged to provide an apparatus having a high general-purpose condition.
In the unwinding apparatus for the wire material under constant tension according to the invention, the deformation control means (
5
) solves problems accompanied with the curved deformation of the brake band (
4
). As the deformation control means, a plate-shaped guide, a rod-shaped guide or the like may be arranged at one-side or both sides of the brake band (
4
) and adjacent thereto. And also, means for raising a rigidity of the brake band (
4
) itself may be applied as the deformation control means (
5
). For example, a rigid member such as a metal plate, a plastic plate or the like may be adhered to a side surface of the brake band (
4
), or a part of the brake band (
4
) may be replaced with a rigid member such as a metal plate, a plastic plate or the like.
When the deformation control means
5
is arranged in the vicinity of a contact starting point of the brake band (
4
) to the braking face (
3
) in a region ranging from the braking face (
3
) to the brake control means, there can be prevented the curved deformation (W
1
) of the brake band (
4
) in the vicinity of the contact starting point to the braking face (
3
) as shown in FIG.
1
. Thus, the contact area between the brake band (
4
) and the braking face (
3
) is maintained at a constant value and the rapid change or hunting phenomenon in the tension of the wire material (
22
) is prevented.
On the other hand, when the deformation control means (
5
) is ar
Bridgestone Corporation
Nguyen John Q.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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