Textiles: spinning – twisting – and twining – Apparatus and processes – Stranding
Reexamination Certificate
1999-03-09
2001-05-29
Worrell, Danny (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Stranding
C057S361000
Reexamination Certificate
active
06237316
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical fiber ribbon stranding device for superimposing a plurality of optical fiber ribbons and accommodating the optical fiber ribbons thus superimposed into a corresponding one of spiral grooves provided in the outer circumferential surface of a spacer or slotted rod. The present invention also relates to a device for practicing that method.
2. Description of Related Art
An optical fiber cable is provided with aso-called spacer or slotted rod to protect optical fibers. The spacer is formed so that a plastic material, such as polyethylene or the like, is extrusion-molded on and around a tensile body, such as a steel wire, a steel stranded wire, FRP or the like, to have a plurality of spiral grooves in its outer circumferential surface.
FIG. 3
is a perspective view showing an example of such spacer. The spacer
20
includes: a tensile body
21
consisting of a steel wire, a steel stranded wire, FRP or the like; an accommodation body
22
consisting of a plastic material such as polyethylene or the like; and grooves
23
formed spirally in the outer circumferential surface of the accommodation body
22
. The spiral direction of the grooves may be reversed to that shown in FIG.
3
. The spacer
20
can accommodate, in these grooves
23
, various optical fibers including an individual optical fiber in which a glass fiber is coated with a primary coating (consisting of one or more resin layers), and a united optical fibers (i.e. an optical fiber ribbon) in which a plurality of such individual optical fibers are arranged in parallel and further coated together with a secondary coating.
FIG.
4
(A) is a cross-sectional view showing an example of such optical fiber cable, and FIG.
4
(B) is a cross-sectional view of an optical fiber ribbon. A plurality of individual optical fibers
33
a
each of which is formed of a glass fiber coated with ultraviolet curing resin or the like as a primary coating are arranged in parallel, and entirely coated with coating
33
b
of ultraviolet curing resin or the like as a secondary coating, thereby forming an optical fiber ribbon
33
.
An accommodation body
32
consisting of a plastic material and having a plurality of spiral grooves
32
a
is formed on and around a tensile body
31
consisting of a steel wire, a steel stranded wire, FRP or the like, thereby forming a spacer. A plurality of optical fiber ribbons
33
are superimposed one on another and accommodated in each of the grooves
32
a
of the spacer. A wrapping
34
is applied onto the spacer. An external coating
35
consisting of a plastic material or the like is provided on the wrapping
34
. Then, an optical fiber cable is formed.
To manufacture the optical fiber cable of this type, a stranding step of superimposing and accommodating the optical fiber ribbons in each of spiral grooves of a spacer is required. FIG.
5
(A) is a front view showing an example of a stranding device used for practicing such stranding step. A spacer
41
is fed out of a reel
38
, advanced to the right straight by a take-up device (a belt capstan)
45
while being braked by a tension giving device (a belt capstan)
39
, and then taken up on a reel
46
. At least the tension giving device
39
and the take-up device
45
are rotated around their axes in association with the advance of the spacer
41
in the direction of the spiral grooves of the spacer
41
. That is, the devices
39
and
45
are rotated at the same cycle as the spiral grooves are rotated in association with the advance of the spacer
41
. Consequently, each of the grooves extending between the tension giving device
39
and the take-up device
45
is viewed as if it is kept in the same position with respect to a fixed point of the earth.
As illustrated, optical fiber ribbons
42
are fed out of a plurality of reels
37
respectively, passed through a groove formed in a guide die
40
, and introduced into a groove of the spacer
41
advanced in the above-described manner. In this case, since the groove of the spacer
41
intersects the guide die
40
in the same position with respect to the earth, the guide die
40
can introduce the optical fiber ribbons
42
into the groove of the spacer
41
even if the guide die
40
is arranged stationary. Note that optical fiber ribbons, which are omitted in FIGS.
5
(A) and
5
(B) to simplify the illustration, are similarly fed out of respective reels and accommodated by the guide die
40
into corresponding grooves of the spacer
41
. The reference numeral
43
represents a pressing die; and
44
, a spacer in which optical fiber ribbons have been accommodated in the grooves. A rough winding, a tape winding and so on may be applied onto the spacer
44
before or after the spacer
44
is passed through the pressing die
43
depending on the need.
FIG.
5
(B) is an enlarged front view of FIG.
5
(A), showing how the guide die
40
guides the optical fiber ribbons
42
into the groove of the spacer
41
. FIG.
5
(
c
) is a perspective view showing the guide die
40
. A plurality of optical fiber ribbons
42
are passed through each of the grooves
40
a
formed in the guide die
40
to be introduced into a corresponding one of the grooves of the spacer
41
.
The guide die
40
is provided with a circular hole
40
b
circular in section and extending along its central axis so that spacer
41
is passes through the circular hole
40
b
. Further, a plurality of inwardly projecting protrusions (not shown) are fixedly provided on the inner circumference of the circular hole
40
b
of the guide die
40
and inserted into the respective grooves of the spacer
41
so that the grooves of the spacer
41
surely intersect the same positions of the guide die
40
, respectively, with respect to the fixed point of the earth when the spacer
41
is passed through the guide die
40
.
In place of the guide die
40
, a thin disc-like plate having a circular central hole and a plurality of circular holes arranged about the central hole may be used to guide a plurality of optical fiber ribbons
42
to the spacer
41
.
Such a method is also available that optical fiber ribbons are introduced into grooves of a spacer without using a guide die. FIGS.
6
(A) and (B) are a perspective view and a front view, respectively, showing an example of such method, in which a plurality of optical fiber ribbons
42
are introduced one by one into the groove
41
a of a spacer
41
while being separated one from another by a spring-like ring (i.e. a spiral separator)
47
so that the optical fiber ribbons
42
are placed in the groove
41
a
in a superimposed fashion.
Of the manufacturing methods described above, the method employing a guide die to introduce optical fiber ribbons into each groove of a spacer has the following defect: The optical fiber ribbons that are to be superimposed in one groove of the spacer are inserted into corresponding one groove of the guide die, but the mutual positional relationship of the individual optical fiber ribbons is not fixed so that the superimposed state is unstable within the guide die. Consequently, the optical fiber ribbons are likely to be inclined within the groove of the guide die, and the superimposing order of the optical fiber ribbons is changed at the worst. That it, the alignment is apt to be disordered.
In the method employing a spiral separator, the mutual positional relationship of individual optical fiber ribbons is not fixed, so that the optical fiber ribbons are passed through the corresponding ring parts of the spiral separator in a state where the superimposed state is not determined. Since the optical fiber ribbons enter into the corresponding ring parts of the spiral separator in the unstable state, the optical fiber ribbons may be stripped or damaged by the ring parts of the spiral separator.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical fiber ribbon stranding device and an optical fiber ribbon stranding method, which are free from the above-noted disadv
Saito Koichi
Takahashi Ken
Watanabe Masakazu
Yasui Masatoshi
McDermott & Will & Emery
Sumitomo Electric Industries Ltd.
Worrell Danny
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