DESC:TECHNICAL FIELD
[0001] The present disclosure relates to the field of an optical fiber cable. More particularly, the present disclosure relates to a method of manufacturing of the optical fiber cable. The present application is based on, and claims priority from an Indian Application Number 4842/MUM/2015 filed on 23rd December, 2015, the disclosure of which is hereby incorporated by reference herein.
BACKGROUND
[0002] In this era of technological advancements, optical fiber cables are finding increasing importance in modern communication systems and are being vastly used in telecommunication, broadband communication, communication over passive optical networks (PONs), and the like. Telecommunication companies use optical fiber cables to transmit telephone and television signals, and also facilitate internet communication. Moreover, these optical fiber cables are utilized for various indoor applications, outdoor applications, underground applications and underwater applications. These optical fiber cables are laid down in various indoor and outdoor locations for various operations.

[0003] Traditionally, an optical fiber cable is constructed by stranding buffer tubes with optical fibers around a central strength member. The technique utilized for the stranding is commonly known as SZ stranding. Traditionally, the stranding process is followed by a sheathing process which employs one or more binder threads to bind the buffer tubes or micromodules. Typically, these one or more binders are applied using a yarn server which binds the micromodules at specific locations. The buffer tubes are bind in order to retain a lay length of the micromodules after which aramid yarn strength members are applied followed by a water blocking tape for moisture absorption. Lastly, an outer jacket is applied to cover the inner layers of the optical fiber cable.

[0004] In general, this stranding and sheathing is performed individually due to which the micromodules suffer extensive bending stresses and crush which affects the attenuation of fibers. The desired lay length can be achieved by using binder elements just after the SZ strander. In a conventional micromodule design, two binders may be used to bind the micromodules. The aramid yarns are applied after binding the micromodules helically using a yarn server. The drawback of these methods is an additional need of one or more binder heads. These binder heads increase cost of the optical fiber cable and escalate space requirements for additional machines.

[0005] In light of the foregoing discussion, there exists a need for a method which overcomes the above cited drawbacks.

OBJECT OF THE DISCLOSURE
[0006] A primary object of the present disclosure is to provide a method of manufacturing of optical fiber cable.

[0007] Another object of the present disclosure is to decrease a separation between a binder die and a strander die of the stranding machine and the yarn server.

[0008] Yet another object of the present disclosure is to reverse the rotation of the yarn server.
[0009] Yet another object of the present disclosure is to retain the lay length of the plurality of sleeves and the yarn layer.

[0010] Yet another object of the present disclosure is to use yarns as binding member and strength member.
SUMMARY
[0011] In an aspect, the present disclosure provides a method for manufacturing an optical fiber cable. The method includes positioning each of a plurality of sleeves along a longitudinal axis on a stranding machine. Further, the method includes stranding each of the plurality of sleeves through the stranding machine. Furthermore, the method includes binding each of the plurality of sleeves with a first layer of yarn. Moreover, each of the plurality of sleeves encloses a plurality of optical fibers. Each of the plurality of sleeves is positioned to pass through a plurality of guide plates. Accordingly, each of the plurality of guide plates provides support to each of the plurality of sleeves and generates an SZ lay. Further, the stranding of the plurality of sleeves is a twisting of plurality of sleeves to form a stranded core. The stranded core is flexible and has a uniform stress distribution under bending stress. Furthermore, the binding of the plurality of sleeves is performed by rolling the first layer of yarn through a binder die. The binder die is present substantially around the plurality of sleeves and the binder die and a strander die of the stranding machine is positioned at a horizontal separation. The horizontal separation is in a range of 50 millimeters-200 millimeters. The binder die is detachably attached to a first distal end of a yarn server.
[0012] In an embodiment of the present disclosure, the method further includes alignment of each of the plurality of sleeves substantially along the longitudinal axis.
[0013] In an embodiment of the present disclosure, the first distal end of the yarn server is present close to a location of the strander die of the strander machine.

[0014] In an embodiment of the present disclosure, the binding of each of the plurality of sleeves with the first layer is in a helical pattern.

[0015] In an embodiment of the present disclosure, the yarn server rolls the first layer of yarn around the plurality of sleeves in a pre-defined direction.

[0016] In an embodiment of the present disclosure, the plurality of sleeves is helically stranded substantially along the longitudinal axis. The plurality of sleeves is helically stranded by turning each of the plurality of sleeves substantially along the longitudinal axis periodically in a pre-determined direction. The pre-determined direction is either a clockwise direction or an anticlockwise direction.

[0017] In an embodiment of the present disclosure, the plurality of sleeves is S-Z stranded substantially along the longitudinal axis. Each of the plurality of sleeves is substantially stranded along the longitudinal axis in a first direction of winding in an S-shape alternating with a second direction of winding in a Z-shape.

[0018] In an embodiment of the present disclosure, the horizontal separation between the strander die and the binder die provides retention of a lay length of the plurality of sleeves.

[0019] In an embodiment of the present disclosure, the first layer acts as a tensile element and a binder element. The first layer is made of an aramid yarn.

[0020] In an embodiment of the present disclosure, each of the plurality of sleeves is a buffer tube for encapsulation of the plurality of optical fibers. The plurality of sleeves provides mechanical isolation, physical damage protection and identification of each of the plurality of fibers.
STATEMENT OF THE DISCLOSURE
[0021] The present disclosure relates to a method for manufacturing an optical fiber cable. The method includes positioning each of a plurality of sleeves along a longitudinal axis on a stranding machine. Further, the method includes stranding each of the plurality of sleeves through the stranding machine. Furthermore, the method includes binding each of the plurality of sleeves with a first layer of yarn. Moreover, each of the plurality of sleeves encloses a plurality of optical fibers. Each of the plurality of sleeves is positioned to pass through a plurality of guide plates. Accordingly, each of the plurality of guide plates provides support to each of the plurality of sleeves and generates an SZ lay. Further, the stranding of the plurality of sleeves is a twisting of plurality of sleeves to form a stranded core. The stranded core is flexible and has a uniform stress distribution under bending stress. Furthermore, the binding of the plurality of sleeves is performed by rolling the first layer of yarn through a binder die. The binder die is present substantially around the plurality of sleeves and the binder die and a strander die of the stranding machine is positioned at a horizontal separation. The horizontal separation is in a range of 50 millimeters-200 millimeters. The binder die is detachably attached to a first distal end of a yarn server.
BRIEF DESCRIPTION OF FIGURES
[0022] Having thus described the disclosure in general terms, reference will now be made to the accompanying figures, wherein:

[0023] FIG. 1 illustrates a cross sectional view of an optical fiber cable with a central strength member, in accordance with an embodiment of the present disclosure;

[0024] FIG. 2A illustrates the cross sectional view of the optical fiber cable without the central strength member, in accordance with another embodiment of the present disclosure;

[0025] FIG. 2A illustrates a perspective view of the optical fiber cable of FIG. 2B, in accordance with another embodiment of the present disclosure;

[0026] FIG. 3A illustrates the cross sectional view of a direct buried optical fiber cable having a high crush resistance, in accordance with yet another embodiment of the present disclosure;

[0027] FIG. 3B illustrates the perspective view of the optical fiber cable of FIG. 3A, in accordance with another embodiment of the present disclosure;

[0028] FIG. 4A illustrates the cross sectional view of the direct buried and an aerial optical fiber cable, in accordance with yet another embodiment of the present disclosure;
[0029] FIG. 4A illustrates the perspective view of the optical fiber cable of FIG. 4A, in accordance with yet another embodiment of the present disclosure;
[0030] FIG. 5A and FIG. 5B illustrate perspective views of a yarn server, in accordance with various embodiments of the present disclosure; and

[0031] FIG. 6 illustrates a flow chart of a method of manufacturing of the optical fiber cable, in accordance with various embodiments of the present disclosure.
[0032] It should be noted that the accompanying figures are intended to present illustrations of exemplary embodiments of the present disclosure. These figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.

DETAILED DESCRIPTION
[0033] Reference will now be made in detail to selected embodiments of the present disclosure in conjunction with accompanying figures. The embodiments described herein are not intended to limit the scope of the disclosure, and the present disclosure should not be construed as limited to the embodiments described. This disclosure may be embodied in different forms without departing from the scope and spirit of the disclosure. It should be understood that the accompanying figures are intended and provided to illustrate embodiments of the disclosure described below and are not necessarily drawn to scale. In the drawings, like numbers refer to like elements throughout, and thicknesses and dimensions of some components may be exaggerated for providing better clarity and ease of understanding.

[0034] It should be noted that the terms "first", "second", and the like, herein do not denote any order, ranking, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[0035] FIG. 1A illustrates a cross sectional view of an optical fiber cable 100 with a central strength member, in accordance with an embodiment of the present disclosure. The optical fiber cable 100 is a high density optical fiber cable 100. Further, the optical fiber cable 100 has a pre-defined structure. The pre-defined structure of the optical fiber cable 100 is based on a layered arrangement of cable elements.

[0036] The pre-defined structure of the optical fiber cable 100 includes a central strength member 102, a plurality of sleeves 104a-104g, a plurality of optical fibers 106, one or more yarn threads 108a-108c and a first layer 110. Further, the optical fiber cable 100 includes a second layer 112, a third layer 114, a plurality of strength members 116a-b. Furthermore, the optical fiber cable 100 includes a first coating of ethylene acrylic acid (hereinafter “EAA”) 118a, a second coating of EAA 118b, a plurality of rip cords 120a-b. The central strength member 102 provides a support to the plurality of sleeves 104a-104g. In addition, the central strength member 102 is located at a center of the optical fiber cable 100.

[0037] Furthermore, the central strength member 102 is present longitudinally along length of the optical fiber cable 100. In an embodiment of the present disclosure, the central strength member 102 is made of any stiff material. The material provides bend and anti-buckle properties to the central strength member 102. In another embodiment of the present disclosure, the central strength member 102 is made of a fiber reinforced plastic (hereinafter “FRP”). In yet another embodiment of the present disclosure, the central strength member 102 is made of aramid reinforced plastic (hereinafter “ARP”). In yet another embodiment of the present disclosure, the central strength member 102 is made of a metallic wire. In yet another embodiment of the present disclosure, the central strength member is made of FRP with coated steel wire. In addition, the central strength member 102 is surrounded by the plurality of sleeves 104a–104g.

[0038] Further, the plurality of sleeves 104a–104g is arranged in a stranding pattern. In an embodiment of the present disclosure, the stranding pattern of the plurality of sleeves 104a-104g is an S-Z stranding pattern. In another embodiment of the present disclosure, the stranding pattern of the plurality of sleeves 104a-104g is a helical stranding pattern. The plurality of sleeves 104a–104g is wound in a first direction around the central strength member 102 for a pre-defined number of turns. The pre-defined number of turns is in a range of 2-5. In an embodiment of the present disclosure, the first direction of wound is clockwise. In another embodiment of the present disclosure, the first direction is anticlockwise. Furthermore, the plurality of sleeves 104a-104g reverses direction at pre-defined locations periodically along a length of the optical fiber cable 100. The pre-defined location for reversal in a direction of stranding of the plurality of sleeves 104a-104g is a reversal point. Moreover, the plurality of sleeves 104a-104g suffers a bending stress and crush during manufacturing process of the optical fiber cable 100. The manufacturing process of the optical fiber cable 100 requires a uniform stress distribution along the length of the optical fiber cable 100. The uniform stress distribution along the length of the optical fiber cable 100 is achieved from retention of a lay length.

[0039] In addition, the lay length is measured as a distance between each sleeve after a rotation of the same sleeve. The plurality of sleeves 104a-104g is wound in the stranding pattern by a stranding machine. In another embodiment of the present disclosure, a mechanism of retention of the lay length before each of the reversal points is prior to a change in the direction from the anticlockwise direction to the clockwise direction.

[0040] The plurality of sleeves 104a-104g encloses the plurality of optical fibers 106. Each sleeve of the plurality of sleeves 104a-104g encloses a bundle of optical fibers of the plurality of optical fibers 106. In an embodiment of the present disclosure, the bundle of optical fibers of the plurality of optical fibers 106 is color coded. In another embodiment of the present disclosure, the set of optical fibers of the plurality of optical fibers 106 possesses a uniform color.

[0041] Furthermore, the one or more yarn threads 108a-108c are embedded in gaps between each sleeve of the plurality of sleeves 104a-104g. The one or more yarn threads 108a-108c provides improvement in a bend resistance. The one or more yarn threads 108a-108c absorbs water or moisture entering the optical fiber cable 100. In addition, the one or more yarn threads 108a-108c swells to block ingression of the water or the moisture.

[0042] The first layer 110 surrounds the plurality of sleeves 108a-108c. In an embodiment of the present disclosure, the first layer 110 is made of an aramid yarn. In another embodiment of the present disclosure, the first layer 110 is made of any suitable material. Further, the first layer 110 surrounds the plurality of sleeves 104a-104g in a helical pattern. In addition, the manufacturing process of the optical fiber cable 100 involves usage of a yarn server 500 (as shown in FIG. 5A and FIG. 5B). The yarn server 500 facilitates the retention of the lay length and an application of the first layer 110. The first layer 110 holds each of the reversal points prior to a change in the direction from clockwise to anticlockwise.

[0043] Further, the yarn server 500 rolls the first layer 110 around the plurality of sleeves in a pre-defined direction. In addition, the pre-defined direction of the yarn server 500 at the reversal point is reversed to utilize first layer 110 as a binder and a strength member. The first layer 110 provides nearly a constant lay length along the length of the optical fiber cable 100. Moreover, the first layer 110 balances a residual bending stress in the plurality of sleeves 104a-104g. The first layer 110 present at each reversal point improves stability and the uniform stress distribution of the plurality of optical fibers 106 inside the optical fiber cable 100.

[0044] Furthermore, the second layer 112 surrounds the first layer 110. The second layer 112 is a water blocking tape. The second layer 112 prevents the ingression of the water and the moisture from ambient surrounding. The second layer 112 absorbs the water and the moisture. Accordingly, the second layer 112 swells to block passage of the water and the moisture.

[0045] The third layer 114 encloses the second layer 112. The third layer 114 is an outermost layer of the optical fiber cable 100 that interacts directly with the ambient environment. In an embodiment of the present disclosure, the third layer 114 is made of any suitable material. In another embodiment of the present disclosure, the third layer 114 is made of a high density polyethylene material. In addition, the third layer 114 provides a crush resistance, an abrasion resistance, a chemical resistance and a bend resistance to the optical fiber cable 100.

[0046] The plurality of strength members 116a-b are embedded in the third layer 114. The plurality of strength members 116a-b is a tensile strength member. The plurality of strength members 116a-b are present diametrically opposite to each other in the third layer 114. In addition, each of the plurality of strength members 116a-b is enclosed with the coating of ethylene acrylic acid 118a-b. Moreover, the third layer 114 may have more or less than two strength members. Each of the plurality of strength members 116a-b may be made of any material. Examples of the material include but may not be limited to fiber reinforce plastic (hereafter “FRP”), steel, copper and the aramid reinforce plastic. The coating of EAA 118a-b provides water resistance, flexibility, and the chemical resistance to the optical fiber cable 100.

[0047] Further, a lower portion of the third layer 114 is embedded with the plurality of rip cords 120a-b. In addition, the plurality of rip cords 120b is present parallel to each of the plurality of strength member 116b. The plurality of rip cords 120a-b is present along the length of the optical fiber cable 100. The plurality of rip cords 120a-b facilitates removal of the third layer 114.

[0048] Further, it may be noted that in the FIG. 1A, the optical fiber cable 100 includes 7 sleeves 104a-104g; however, those skilled in the art would appreciate that more or less number of sleeves are present in the optical fiber cable 100. Furthermore, it may be noted that the optical fiber cable 100 includes the 3 yarn threads 108a-108c; however, those skilled in the art would appreciate that more or less number of yarn threads are present in the optical fiber cables 100.

[0049] FIG. 2A illustrates the cross-sectional view of the optical fiber cable 200, in accordance with another embodiment of the present disclosure. The cross sectional view describes a layered structure and distribution of discrete elements of the optical fiber cable 200. The layered structure of the optical fiber cable 200 includes a plurality of sleeves 202a-202k, a plurality of optical fibers 204, one or more yarn threads 206a-206c and a first layer 208. In addition, the layered structure of the optical fiber cable 200 includes a second layer 210, a third layer 212 and a plurality of strength members 214a-b. Moreover, the layered structure of the optical fiber cable 200 includes coating of EAA 216a-b and a plurality of rip cord 218a-b.

[0050] The plurality of sleeves 202a-202k is the buffer tubes of the optical fiber cable 200. The plurality of sleeves 202a-202k may be made from any buffer material. In an embodiment of the present disclosure, each sleeve of the plurality of sleeves 202a-202k is made of thermoplastic co-polyester elastomer (hereinafter “TPE”). In another embodiment of the present disclosure, the plurality of sleeves 202a-202k may be made from any suitable material. In yet another embodiment of the present disclosure, the sleeve is made of a LSZH material filled with waterproof jelly. The plurality of sleeves 202a-202k may be more or less than 12 in number.

[0051] In addition, each sleeve is described by an inner diameter and an outer diameter. The inner diameter is 1.05 mm and the outer diameter is 1.3 mm. The plurality of sleeves 202a-202k is SZ stranded about each other to form a stranded core. The plurality of sleeves 202a-202k is rotated in an S shape for the specific number of the turns. In an embodiment of the present disclosure, the specific number of turns lies in the range of 2-5. Further, the direction of the rotation of the plurality of sleeves 202a-202k is reversed. The reversal of the direction of the rotation is performed to strand the plurality of sleeves to a Z shape. In an embodiment of the present disclosure, the reversal is followed by the specific number of the turns. In another embodiment of the present disclosure, the reversal is followed by 2-5 turns of the plurality of sleeves 202a-202k.

[0052] Furthermore, the plurality of sleeves 202a-202k is SZ stranded around a longitudinal axis of the optical fiber cable 200 in sections. In addition, the direction of the SZ stranding in the S-shape alternates with the sections in the opposite direction of the SZ stranding of the Z shape. Moreover, the SZ stranding provides the uniform stress distribution to each of the plurality of sleeves 202a-202k. The stranding of the plurality of sleeves 202a-202k is performed to obtain the lay length. In general, the lay length is measured as distance between each sleeve after a rotation of the same sleeve in the SZ stranding of the plurality of sleeves 202a-202k. In addition, the average lay length is defined by a distance between reversal points divided by a number of turns between reversals. In addition, a shorter lay length denotes a higher amount of bend stress and fiber surface stress. Similarly, a longer lay length denotes an uneven stress distribution and leads to high attenuation losses.

[0053] The plurality of sleeves 202a-202k includes the plurality of optical fibers 204. In addition, the plurality of optical fibers 204 is divided among each of the plurality of sleeves 202a-202k. Each sleeve of the plurality of sleeves 202a-202k may include more or less than 12 fibers. Further, the plurality of optical fibers 204 is color coded for each sleeve of the plurality of sleeves 202a-202k. In an embodiment of the present disclosure, the optical fiber cable 200 has a total of 12 optical fibers with an overall diameter of about four to seven millimeters. In another embodiment of the present disclosure, the optical fiber cable 200 has the total of 24 optical fibers with the overall diameter of about 6.5 to 8.5 mm. In yet another embodiment of the present disclosure, the optical fiber cable 200 has the total of 48 optical fibers with the overall diameter of about 7.2 to 9.2 millimeters. In yet another embodiment, the optical fiber cable 200 has the total of 72 optical fibers 204 with the overall diameter of about 8.2 to 10.2 mm. In yet another embodiment, the optical fiber cable 200 has the total of 96 optical fibers with the overall diameter of about 9.5 to 11.5 mm. In yet another embodiment of the present disclosure, the optical fiber cable 200 has the total of 144 optical fibers with the overall diameter of about 10.4 to 12.4 mm. In yet another embodiment, the optical fiber cable 200 has the total of 288 optical fibers with the overall diameter of about 12.9 to 14.9 millimeters. In yet another embodiment, the optical fiber cable 200 has the total of 432 optical fibers with the overall diameter of about 15.4 to 17.4 millimeters. In yet another embodiment of the present disclosure, the optical fiber cable 200 has the total of 576 optical fibers with the overall diameter of about 15 mm to 17.5 mm.

[0054] The one or more yarn threads 206a-206c are dispersed in gaps between each of the plurality of sleeves 202a-202k. The one or more yarn threads 206a-206c protects the plurality of sleeves 202a-202k from the water ingression or the moisture interaction. The one or more yarn threads 206a-206c swell from absorption of the water and the moisture. Furthermore, the plurality of sleeves 202a-202k is enclosed by the layer of the high strengthening yarn 208. The yarn server is used to helically wind the layer of the high strengthening yarn 208. In addition, the layer of the high strengthening aramid yarn is made of the aramid yarn fibers. The layer of the high strengthening yarn 208 is the binding element for the SZ stranded plurality of sleeves 202a-202k.

[0055] Furthermore, the first layer 208 (clearly seen in FIG. 2B) reduces the stress on the plurality of optical fibers 204 in a high tensile load environment. In general, the plurality of sleeves 202a-202k tends to open up after the specific number of turns if the layer of high strengthening aramid yarn 208 is not employed. The SZ stranded plurality of sleeves 202a-202k opens up due to reverse oscillations in the optical fiber cable 200. The first layer 208 preserves the lay length of the plurality of sleeves 202a-202k in the optical fiber cable 200. In addition, the second layer 210 surrounds the first layer 208. The second layer 210 provides barrier to prevent the ingression of the water and the moisture. The second layer 210 is preferably placed underneath the third layer 212. The second layer 210 prevents sticking of the first layer 208 and the third layer 212 during a sheathing process when molten jacket material sticks to yarns.

[0056] In addition, the third layer 212 surrounds the second layer 210. Further, the third layer 212 is made up of a strong polymer based jacket with the inherent ability to resist crushes, kinks and tensile stress. In an embodiment of the present disclosure, the third layer1 212 is made of the HDPE material. In another embodiment of the present disclosure, the third layer 212 is made of a medium density polyethylene material. In yet another embodiment of the present disclosure, the third layer 212 is made of any other suitable material. In general, the thickness of the third layer 212 depends on the FRP embedding members. Accordingly, the thickness of the third layer 212 has a minimum value of +0.6mm owing to an addition of FRP diameter of + 0.3mm on both sides of FRP.

[0057] The plurality of strength members 214a-b are embedded in the third layer 212. In an embodiment of the present disclosure, the third layer 212 can contain two or more strength members. In addition, each of the plurality of strength members 214a-b has a circular cross section. The first strength member 116a and the second strength member 116b extend longitudinally in the third layer 212 along the length of the optical fiber cable 200. Moreover, the plurality of strength members 214a-b provide robustness and tensile strength to the optical fiber cable 200. In addition, an increase in the length of the plurality of sleeves 202a-202k results in micro and macro bends inside the plurality of optical fibers 204. The micro and the macro bends results in higher attenuation or power loss in the optical fiber cable 200. Accordingly, the plurality of strength members 214a-b act as anti-buckle or anti-shrink elements. In addition, the plurality of strength members 214a-b prevents the third layer 210 from shrinkage.

[0058] Furthermore, each of the plurality of strength members 214a-b is present in the pre-determined location. In an embodiment of the present disclosure, the location of each of the plurality of strength members 214a-b is diametrically opposite in a vertical plane. In another embodiment of the present disclosure, the location of each of the plurality of strength members 214a-b is opposite in a horizontal plane. In an embodiment of the present disclosure, each of the plurality of strength members 214a-b may be made of any suitable metal or non-metal (as explained above in the detailed description of the FIG. 1).

[0059] In addition, the location of each of the plurality of strength members 214a-b is covered with the coating of EAA 216a-b. The coating of EAA 216a-b provides a robust bond of the location of each of the plurality of strength members 214a-b with the third layer 212. Moreover, the plurality of rip cords 218a-b is present diametrically opposite between the second layer 210 and the third layer 212. The plurality of rip cords 218a-b extends longitudinally to strip or open the third layer 212. In addition, the optical fiber cable 200 may have more or less than 2 rip cords. The plurality of rip cords 218a-b is made of polyester.

[0060] FIG. 3A illustrates the cross sectional view of a direct buried optical fiber cable 300, in accordance with yet another embodiment of the present disclosure. The crush resistance is achieved from the optical fiber cable 300 by application of a layer of glass fiber yarns 320 and a fourth layer 322.

[0061] The optical fiber cable 300 possesses two layers of sheath and two layers of strengthening yarns to provide a robust and strong fiber cable network for outdoor applications. In addition, the cross sectional view describes the layered structure and the distribution of the discrete elements of the optical fiber cable 300. The layered structure of the optical fiber cable 300 includes a plurality of sleeves 302a-302k, a plurality of optical fibers 304, one or more yarn threads 306a-306c and a first layer 308. In addition, the layered structure of the optical fiber cable 300 includes a second layer 310, a third layer 312 and a plurality of strength members 314a-b. Moreover, the layered structure of the optical fiber cable 300 includes a coating of EAA 316a-b (clearly shown in FIG. 3B) and a plurality of rip cords 318a-b. Further, the layered structure of the optical fiber cable 300 includes the layer of glass fiber yarn 320 and the fourth layer 322.

[0062] In general, each of the plurality of sleeves 302a-302k is a buffer tube of the optical fiber cable 300. In an embodiment of the present disclosure, the plurality of sleeves 302a-302k is made from thermoplastic co-polyester elastomer (hereafter “TPE”). In another embodiment of the present disclosure, the plurality of sleeves 302a-302k may be made from any suitable material. In addition, each sleeve is described by an inner diameter and an outer diameter. The inner diameter is 1.05 mm and the outer diameter is 1.3 mm. The plurality of sleeves 302a-302k are SZ stranded about each other to form a stranded core (as explained above in the detailed description of the FIG. 1 and FIG. 2A). The plurality of sleeves 302a-302k includes the plurality of optical fibers 304.

[0063] In addition, the plurality of optical fibers 304 is divided among each of the plurality of sleeves 302a-302k. Each sleeve of the plurality of sleeves 302a-302k may include more or less than 12 fibers. In addition, the plurality of optical fibers 304 is standard ITU-T G.652D silica optical fibers. Further, the pluralities of optical fibers 304 are color coded for each sleeve of the plurality of sleeves 302a-302k.

[0064] Further, the one or more yarn threads 306a-306c is dispersed between each of the plurality of sleeves 302a-302k. The one or more yarn threads 306a-306c protects the plurality of sleeves 302a-302k from the water ingression or the moisture interaction. The one or more yarn threads 306a-306c swell from absorption of the water and the moisture. The one or more yarn threads 306a-306c are super absorbent polymer (hereafter “SAP”) coated polyester threads. Furthermore, the plurality of sleeves 302a-302k is enclosed by the first layer 308 (as stated above in the detailed description of the FIG. 1B). In addition, the first layer 308 forms a circular cross-section around stranded core. The circular cross-section is described by core diameter.

[0065] In addition, the second layer 310 surrounds the first layer 308. The second layer 310 provides barrier to prevent the ingression of the water and the moisture (as stated above in the detailed description of the FIG. 1 and FIG. 2A). In addition, the third layer 312 surrounds the second layer 310. Further, the third layer 312 is made up of the strong polymer based jacket with the inherent ability to resist crushes, kinks and tensile stress. In an embodiment of the present disclosure, the third layer 312 is made of the high density polyethylene material. In another embodiment of the present disclosure, the third layer 312 is made of a medium density polyethylene material. In yet another embodiment of the present disclosure, the third layer 312 is made of any other suitable material.

[0066] Further, the plurality of strength member 314a-b is embedded in the third layer 312. In an embodiment of the present disclosure, the third layer 312 can contain two or more strength members. In addition, each of the plurality of strength members 314a-b is circular in cross section (as explained above in the detailed description of the FIG. 1 and FIG. 2A). In an embodiment of the present disclosure, the diameter of each of the plurality of strength members 314a-b is about 1.2 mm. In addition, each of the plurality of strength members 314a-b is covered with the coating of EAA 316a-b (as previously described above in the detailed description of the FIG. 1 and FIG. 2A). Moreover, the plurality of rip cords 318a-b are present diametrically opposite between the second layer 310 and the third layer 312 (as explained above in the detailed description of FIG. 1 and FIG. 2A).

[0067] Furthermore, the layer of fiber glass yarn 320 is wound helically around the third layer 312 to provide rodent protection to the optical fiber cable 300. The glass fiber yarn 320 provides high crush resistance to the optical fiber cable 300. The fourth layer 322 surrounds and encloses the glass fiber yarns 320 (as described above in the detailed description of the FIG. 1 and FIG. 2A). In an embodiment of the present disclosure, the thickness of the fourth layer 322 is about 1.5 millimeters. The glass fiber yarns 322 are enclosed between the third layer 312 and the fourth layer 322 to provide additional protection and crush resistance to the optical fiber cable 300.

[0068] FIG. 4A illustrates the cross sectional view of the direct buried and an aerial optical fiber cable 400, in accordance with yet another embodiment of the present disclosure. The direct buried optical fiber cable 400 is resistant to the rodent bites and resistant to crush forces. In addition, the directly buried optical fiber cable 400 can be directly buried underground. The resistance to the crush forces and the rodent bites is achieved from wounds of a plurality of tensile strength members 420a-420h, a third layer 412 sheath and a fourth layer 422.

[0069] Further, the cross sectional view describes the layered structure and the distribution of the discrete elements of the direct buried optical fiber cable 400 in two dimensions. The layered structure of the optical fiber cable 400 includes a plurality of sleeves 402a-402k, a plurality of optical fibers 404, one or more yarn threads 406a-406c and a first layer 408. In addition, the layered structure of the optical fiber cable 400 includes a second layer 410, the third layer 412 and the plurality of strength members 414a-b. Moreover, the layered structure of the optical fiber cable 400 includes the coating of EAA 416a-b (clearly shown in FIG. 4B) and the plurality of rip cords 318a-b. Further, the layered structure of the optical fiber cable 400 includes the plurality of tensile strength members 420a-420h and the fourth layer 422.

[0070] Further, the plurality of sleeves 402a-402k is the buffer tube of the optical fiber cable 400. In an embodiment of the present disclosure, the plurality of sleeves 402a-402k is made from TPE (as stated above in the detailed description of the FIG. 1C). The plurality of sleeves 402a-402k are SZ stranded about each other to form a stranded core (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A). The plurality of sleeves 402a-402k includes the plurality of optical fibers 404.

[0071] In addition, the plurality of optical fibers 404 is divided among each of the plurality of sleeves 402a-402k. Each sleeve of the plurality of sleeves 402a-402k may include more or less than 12 fibers. In addition, the plurality of optical fibers 404 is standard ITU-T G.652D silica optical fibers. Further, the pluralities of optical fibers 404 are color coded for each sleeve of the plurality of sleeves 402a-402k.

[0072] Further, the one or more yarn threads 406a-406c is dispersed between each of the plurality of sleeves 402a-402k. The one or more yarn threads 406a-406c protect the plurality of sleeves 402a-402k from the water ingression or the moisture interaction (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A). Furthermore, the plurality of sleeves 402a-402k is enclosed by the first layer 408. The yarn server is used to helically wind the first layer 408. In addition, the layer of the high strengthening aramid yarn is made of the aramid yarn fibers. The first layer 408 is the binding element for the SZ stranded plurality of sleeves 402a-402k (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A).

[0073] In addition, the second layer 410 surrounds the first layer 408. The second layer 410 provides barrier to prevent the ingression of the water and the moisture (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A). Further, the second layer 410 is covered with the third layer 412. The third layer 412 is made up of the strong polymer based jacket with the inherent ability to resist crushes, kinks and tensile stress (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A). Further, the plurality of strength member 414a-b is embedded in the third layer 412. In an embodiment of the present disclosure, the third layer 412 can contain two or more number of strength members (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A). In addition, each of the plurality of strength members 414a-b is covered with the coating of EAA 416a-b (as explained above in the detailed description of the FIG. 1A, FIG. 2A and FIG. 3A).

[0074] Furthermore, the plurality of tensile strength members 420a-420h is wound helically around the third layer 412. Each of the plurality of the plurality of tensile strength members 420a-420h provides the resistance against the crush forces, the rodent bite and the underground burial. Further, the plurality of tensile strength members 420a-420h may vary in number depending on requirements of the directly buried optical fiber cable and aerial optical fiber cable. In an embodiment, the plurality of tensile strength members 420a-420h is made up of FRP. In another embodiment of the present disclosure, other materials can also be used based on requirements and suitability. The other materials include copper, steel, non-metals and aramids. In an embodiment of the present disclosure, each plurality of tensile strength members of the plurality of tensile strength members 420a-420h may be a flat FRP. In another embodiment of the present disclosure, each plurality of tensile strength members of the plurality of tensile strength members may be round FRP. The breadth of each plurality of tensile strength members of the plurality of tensile strength members 420a-420h is about 3 mm. In addition, the thickness of each plurality of tensile strength members of the plurality of tensile strength members 420a-420h is about 0.7 mm.

[0075] Further, the fourth layer 422 surrounds and encloses the plurality of tensile strength members 420a-420h. In an embodiment of the present disclosure, each plurality of tensile strength members of the plurality of tensile strength members 420a-420h may include round rods. In another embodiment of the present disclosure, each plurality of tensile strength members of the plurality of tensile strength members 420a-420h may include flat rods. The round rods or the flat rods are positioned between the third layer 412 and fourth layers 422. In an embodiment of the present disclosure the fourth layer 422 is made of the HDPE. In another embodiment of the present disclosure, the fourth layer 422 is made of MDPE. In yet another embodiment of the present disclosure, the fourth layer 422 is made of any suitable material. In addition, the thickness of the fourth layer 422 is about 1.5 mm.

[0076] FIG. 5A illustrates a perspective view of a yarn server 500, in accordance with various embodiments of the present disclosure. It may be noted that to explain the structural elements of the FIG. 5A, references will be made to the structural elements of the FIG. 1, the FIG. 2A, the FIG. 3A and the FIG. 4A. The yarn server 500 binds of the first layer 110 of aramid yarn around a plurality of sleeves 104a-104k of the optical fiber cable 100. In addition, the yarn server 500 performs the binding of the plurality of sleeves 104a-104k to maintain the lay length inside the optical fiber cable 100.

[0077] The optical fiber cable 100 is stranded before application of binders. Further, each of a plurality of sleeves 104a-104k is positioned along the longitudinal axis on a stranding machine. Each of the plurality of sleeves 104a-104k is positioned to pass through a plurality of guide plates 504. Further, the stranding machine performs stranding of each of the plurality of sleeves 104a-104k. The stranding of the plurality of sleeves 104a-104k is performed to achieve flexibility and the uniform stress distribution under bending stress. Further, the yarn server 500 helically binds each of the plurality of sleeves 104a-104k with the first layer 110. The binding of each of the plurality of sleeves 104a-104k is performed for retention of the lay length of the plurality of sleeves 104a-104k. In addition, each of the plurality of sleeves 104a-104k is positioned to pass through a binder die 508 present in the yarn server 500. The binder die 508 is detachably attached to a first distal end of the yarn server 500. The first distal end of the yarn server 500 is present close to a location of the strander die 506 of the strander machine. The binding of the plurality of sleeves 104a-104k is performed by positioning the binder die 508 and the strander die 506 of the strander machine at a horizontal separation in a range of 50 millimeters-200 millimeters.

[0078] The yarn server 500 binds the plurality of sleeves 104a-104k with the first layer 110 of yarn in tandem with the sheathing process. The stranding machine includes one or more guide plates 504 and the strander die 506 at the end of strander. The yarn server 500 includes a binder die 508, a rotation controller and a die head. The plurality of sleeves 104a-104k pass through the one or more guide plates 504. The one or more guide plates 504 provide support to each of the plurality of sleeves 104a-104k and generate an SZ lay.

[0079] Each of the one or more guide plates 504 includes a plurality of holes. Each of the plurality of sleeves 104a-104k passes through each of the plurality of holes present in each of the one or more guide plates 504. In general, the unwinding is facilitated by pulling tension from caterpillar guide plates to guide and generate the lay length. The plurality of sleeves 104a-104k is drawn continuously towards the strander die 506. The strander die 506 is positioned close to entry hole of the binder die 508. The strander die 506 turns the plurality of sleeves 104a-104k to form a stranded sleeve core. The binder die 508 possesses the entry hole and an exit hole for the sheathing of the optical fiber cable 100 in tandem.

[0080] Furthermore, the direction of rotation of the conventional yarn server 500 is reversed. The reversal in the direction of the rotation enables the retention in the lay length of the plurality of sleeves 104a-104k (as explained below in the detailed description of the FIG. 1). In addition, the retention in the lay length provides the uniform stress distribution in the optical fiber cable 100. In addition, the binder die 508 is moved away from the die head to provide continuous wrapping of the first layer 110. The die head rolls in and rolls out the first layer 110 synchronously with the rotation of the yarn server 500.

[0081] FIG. 5B illustrates a zoom in view of the yarn server 500, in accordance with various embodiments of the present disclosure. The yarn server 500 is configured to perform the binding of the plurality of sleeves 104a-104k of the optical fiber cable 100. The plurality of sleeves 104a-104k is stranded (As explained above in the detailed description of FIG. 1).

[0082] In an embodiment of the present disclosure, the first direction of wound is clockwise. In another embodiment of the present disclosure, the first direction is anticlockwise. Furthermore, the plurality of sleeves 104a-104k reverses the direction at the pre-determined locations periodically along the length of the optical fiber cable 100. The specific locations for the reversal in the directions of the plurality of sleeves 104a-104k are the reversal points. Moreover, the plurality of sleeves 104a-104k suffers through the bending stress and the crush inside the optical fiber cable 100. The manufacturing process for the fabrication of the optical fiber cable 100 requires the uniform stress distribution of optical fibers along the length of the optical fiber cable 100. The uniform stress distribution along the length of the optical fiber cable 100 is achieved from regulation of the lay length (as described above in the detailed description of FIG. 5A)

[0083] Moreover, the plurality of sleeves 104a-104k is wound in the stranding pattern with the specific lay length (as described above in the detailed description of FIG. 5A). In addition, the plurality of sleeves 104a-104k wound in the stranding pattern by the stranding machine. In an embodiment of the present disclosure, the stranding machine holds each of the reversal points prior to a change in the direction from clockwise to anticlockwise. In another embodiment of the present disclosure, the stranding machine holds each of the reversal points prior to the change in the direction from anticlockwise to clockwise.

[0084] In addition, the yarn server holds a stranded sleeve core 512. The stranded sleeve core enters the entry hole of the binder die 508. The binder die 508 is a mechanical tool to hold and apply aramid yarn threads 514 around the stranded sleeve core 512. The yarn server 500 rotates at the pre-defined speed in the pre-defined direction. Further, the direction of the rotation of the yarn server 500 is reversed (as described above in the detailed description of FIG. 5A).

[0085] FIG. 6 illustrates a flowchart 600 for manufacturing the optical fiber cable 100, in accordance with various embodiments of the present disclosure. It may be noted that to explain the process steps of the FIG. 6, references will be made to the process steps of the FIG. 1, FIG. 2A, FIG. 2B, FIG. 3A, FIG. 3B, FIG. 4A, FIG. 4B, FIG. 5A and FIG. 5B. The flowchart 600 initiates at step 602. At step 604, each of a plurality of sleeves 104a-104k is positioned along the longitudinal axis on the stranding machine. Each of the plurality of sleeves 104a-104k encloses the plurality of optical fibers 106. Each of the plurality of sleeves 104a-104k is positioned to pass through the plurality of guide plates 504. In addition each of the plurality of guide plates 504 provides support to each of the plurality of sleeves 104a-104k and generates an SZ lay. Further, at step 606, the plurality of sleeves 104a-104k is stranded through the stranding machine. The stranding of the plurality of sleeves 104a-104k is a twisting of plurality of sleeves 104a-104k to form a stranded core having flexibility and a uniform stress distribution under bending stress. Furthermore, at step 608, the first layer 110 of yarn binds each of the plurality of sleeves. The binding of the plurality of sleeves 104a-104k is performed by rolling the first layer 110 of yarn through the binder die 508 substantially around the plurality of sleeves 104a-104k. In addition, the binder die 508 and the strander die 506 of the stranding machine are positioned at a horizontal separation. The horizontal separation is in a range of 50 millimeters-200 millimeters. The binder die 508 is detachably attached to a first distal end of a yarn server 500. The flowchart terminates at step 610.

[0086] It may be noted that the flowchart 600 is explained to have above stated process steps; however, those skilled in the art would appreciate that the flowchart 600 may have more/less number of process steps which may enable all the above stated embodiments of the present disclosure.

[0087] The yarn server of the present disclosure has many advantages over the conventional yarn server. The conventional yarn server performs the stranding of binders around the stranded sleeve core. The conventional yarn server includes the binder die located at a distance of around 1.5 meters from the strander die. The distance of around 1.5 meters between the binder die from the strander die may not help in retention of the lay length of the plurality of sleeves.

[0088] The conventional yarn server binds the stranded sleeve core with the aramid yarn threads with the lower retention of the lay length over the length of the optical fiber cable. In addition, the conventional yarn server binds the stranded sleeve core with non-uniform stress distribution as the plurality of sleeves doesn’t retains the lay length. Further, the conventional yarn server applies the first layer around the stranded sleeve core with an accurate tension control. In conventional methods, the lay length of plurality of sleeves may be retained by using one or more binder heads. Two binders are used in series. The first binder in applied in the clockwise direction and the second binder is applied in the anti-clockwise direction. The application of the two binders is performed after the stranding of the plurality of sleeves.

[0089] The present disclosure eliminates the usage of additional binder heads, thus additional binders which consequently reduces the cost of cable, space requirement for the additional binder heads and cost of binder heads. The method disclosed in the present disclosure helps in retaining the lay length within the range of 30 to 40 times of core diameter. Moreover, the lay length of the aramid yarn is about half of the lay length of the plurality of sleeves. Accordingly, if the lay length of the plurality of sleeves is 150mm, then lay length of the aramid yarn would be 75mm. In addition, the optical fiber cable of the present disclosure is ideal for outdoor, underwater and underground deployment. The use of aramid yarn threads as strength member and binding element just after the SZ stranding of the plurality of sleeves significantly restrains the lay length. The restrained Lay length provides the uniform stress distribution along the optical fiber cable. The uniform stress distribution enables the resistance of the optical fiber cable against bends, stretches and crushes. In addition, the retention in the lay length significantly improves the fiber attenuation.

[0090] Further, the reversal of the direction of rotation of the yarn server of the present disclosure enables the use of aramid yarns as binding elements and strength members. The method of production is cost efficient as binder heads are not required to hold the stranded sleeve core prior to sheathing. In addition, the tandem process of SZ stranding and binding the plurality of sleeves decreases the production time.

[0091] Although, embodiments have been described with reference to specific example embodiments, it will be evident that various modifications, arrangements of components and changes may be made to these embodiments without departing from the broader spirit and scope of the pointing instrument described herein. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

[0092] Many alterations and modifications of the present disclosure will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. It is to be understood that the description above contains many specifications; these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the personally preferred embodiments of this disclosure. Thus, the scope of the disclosure should be determined by the appended claims and their legal equivalents rather than by the examples given.

[0093] The foregoing is illustrative of the present disclosure and is not to be constructed as limiting thereof. Although exemplary embodiments of this disclosure have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure as recited in the claims. The disclosure is defined by the following claims, with equivalents of the claims to be included therein. While the disclosure has been presented with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the disclosure. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the disclosure.

,CLAIMS:CLAIMS

What is claimed is:

1. A method for manufacturing an optical fiber cable, the method comprising:

positioning each of a plurality of sleeves along a longitudinal axis on a stranding machine, wherein each of the plurality of sleeves encloses a plurality of optical fibers, wherein each of the plurality of sleeves is positioned to pass through a plurality of guide plates and wherein each of the plurality of guide plates provide support to each of the plurality of sleeves and generates an SZ lay;

stranding each of the plurality of sleeves through the stranding machine, wherein the stranding of the plurality of sleeves is a twisting of plurality of sleeves to form a stranded core having flexibility and a uniform stress distribution under bending stress; and

binding each of the plurality of sleeves with a first layer of yarn, wherein the binding of the plurality of sleeves is performed by rolling the first layer of yarn through a binder die substantially around the plurality of sleeves and positioning the binder die and a strander die of the stranding machine at a horizontal separation in a range of 50 millimeters-200 millimeters, wherein the binder die is detachably attached to a first distal end of a yarn server.

2. The method as recited in claim 1, further comprising aligning each of the plurality of sleeves substantially along the longitudinal axis.

3. The method as recited in claim 1, wherein the first distal end of the yarn server is present close to a location of the strander die of the strander machine.

4. The method as recited in claim 1, wherein the binding of each of the plurality of sleeves with the first layer is in a helical pattern.

5. The method as recited in claim 1, wherein the yarn server rolls the first layer of yarn around the plurality of sleeves in a pre-defined direction.

6. The method as recited in claim 1, wherein the plurality of sleeves is helically stranded substantially along the longitudinal axis, wherein the plurality of sleeves is helically stranded by turning each of the plurality of sleeves substantially along the longitudinal axis periodically in a pre-determined direction and wherein the pre-determined direction is at least one of a clockwise direction and an anticlockwise direction.

7. The method as recited in claim 1, wherein the plurality of sleeves is S-Z stranded substantially along the longitudinal axis and wherein each of the plurality of sleeves is substantially stranded along the longitudinal axis in a first direction of winding in an S-shape alternating with a second direction of winding in a Z-shape.

8. The method as recited in claim 1, wherein the horizontal separation between the strander die and the binder die provides retention of a lay length of the plurality of sleeves.

9. The method as recited in claim 1, wherein the first layer acts as a tensile element and a binder element and wherein the first layer is made of aramid yarn.

10. The method as recited in claim 1, wherein each of the plurality of sleeves is a buffer tube for encapsulating the plurality of optical fibers to provide mechanical isolation, physical damage protection and identification of each of the plurality of fibers.

Dated: 7th Day of March, 2016 Signature
Arun Kishore Narasani Patent Agent