Butterfly-shaped optical cable for improving additional attenuation and preparation method thereof

Abstract

The invention discloses a butterfly-shaped optical cable for improving additional attenuation and a preparation method of the butterfly-shaped optical cable. The butterfly-shaped optical cable comprises an optical unit, a reinforcing piece and a sheath, the optical unit and the reinforcing member are accommodated in the sheath. The two sides of the optical unit are provided with reinforcing members, the reinforcing members are circular, and the diameter of the reinforcing members is larger than the diameter of a fitting circle of an optical fiber glass part in the optical unit. A buffer part is arranged on a connecting line between the geometric center of the optical unit and the geometric center of the reinforcing piece; and the buffer part has a porous structure. According to the butterfly-shaped optical cable provided by the invention, the buffer part is arranged on the connecting line of the geometric center of the optical unit and the geometric center of the reinforcing piece, and the buffer part is of a porous structure and has the capability of absorbing deformation of the sheath, so that inward extrusion of the deformation of the sheath to the optical unit can be reduced when the butterfly-shaped optical cable body is subjected to lateral pressure; therefore, when the butterfly-shaped optical cable is installed and wired, optical fiber additional attenuation increase caused by nailing vibration impact, lateral pressure and bending is reduced, and additional attenuation of the butterfly-shaped optical cable is improved.

Description

Technical Field

[0001] This invention belongs to the field of optical communication, and more specifically, relates to a butterfly optical cable with improved additional attenuation and its preparation method. Background Technology

[0002] Butterfly-shaped optical cables are a new type of user access optical cable, named for their butterfly-like cross-sectional shape. They are primarily used in FTTX networks, especially as the user drop cable in scenarios such as Fiber to the Home (FTTH), Fiber to the Office (FTTO), and Fiber to the Building (FTTB). Combining the characteristics of indoor flexible optical cables and self-supporting optical cables, butterfly-shaped optical cables offer advantages such as small outer diameter, light weight, low cost, and good flexibility and bending performance, making them crucial in the construction of intelligent buildings, digital communities, campus networks, and local area networks.

[0003] Two symmetrical metal or non-metal reinforcing members, such as glass fiber reinforced polymer (GFRP), are typically installed on both sides of the optical unit of a butterfly-shaped optical cable. The material used for the reinforcing members has high strength and rigidity, providing sufficient tensile strength and resistance to flattening. This design not only gives the butterfly-shaped optical cable good resistance to flattening and tensile forces, but also allows it to travel short distances within underground conduits while maintaining appropriate rigidity to adapt to different laying environments and conditions.

[0004] Nevertheless, when subjected to lateral pressure, vibration, and bending, the additional attenuation of the optical units in butterfly-shaped optical cables increases significantly, resulting in reduced transmission performance and requiring further improvement. Chinese patent document CN117908207B addresses the issue that the optical fibers inside butterfly-shaped cables are prone to breakage due to vibration generated during nailing and the compressive force of the nails. It proposes adding a support sheath to relieve some of the compressive force and prevent external compressive force from acting directly on the optical fiber. However, adding a sheath to resist pressure not only increases material costs and volume but also reduces the bending performance of the butterfly-shaped optical cable. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a butterfly-shaped optical cable with improved additional attenuation and its manufacturing method. The purpose is to improve the additional attenuation of the butterfly-shaped optical cable by setting a buffer part with a porous structure on the line connecting the geometric center of the optical unit and the geometric center of the reinforcement. When the sheath is subjected to lateral pressure, the buffer part absorbs the deformation of the sheath and reduces the lateral pressure of the sheath on the optical unit, thereby improving the additional attenuation of the butterfly-shaped optical cable. This solves the technical problem that the additional attenuation of the butterfly-shaped optical cable increases significantly after being subjected to impact, vibration, lateral pressure, and bending during construction.

[0006] To achieve the above objectives, according to one aspect of the present invention, a butterfly optical cable with improved additional attenuation is provided, comprising an optical unit, a reinforcing member, and a sheath;

[0007] The optical unit and the reinforcing member are housed in the protective sleeve;

[0008] The optical unit is provided with reinforcing members on both sides. The reinforcing members are circular and their diameter is larger than the diameter of the fitted circle of the optical fiber glass part in the optical unit.

[0009] A buffer section is provided on the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member;

[0010] The buffer section has a porous structure.

[0011] Preferably, in the improved additional attenuation butterfly optical cable, the reinforcement is arranged symmetrically about the optical unit axis, and the buffer is arranged symmetrically about the optical unit axis.

[0012] Preferably, in the improved additional attenuation butterfly optical cable, the optical unit and / or the reinforcing member are close to the buffer portion, with a distance of less than or equal to 0.2 mm.

[0013] Preferably, in the improved additional attenuation butterfly optical cable, the buffer portion is symmetrical about the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member, the shape and size of the side of the buffer portion near the reinforcing member matches the outer diameter of the reinforcing member, and the shape and size of the side of the buffer portion near the optical unit matches the outer diameter of the optical unit.

[0014] Preferably, in the butterfly-shaped optical cable for improving additional attenuation, the cross-section of the buffer portion is an isosceles triangle or a near-isosceles triangle, wherein the central axis is symmetrical to the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member, and the end of the buffer portion near the reinforcing member is the base of the isosceles triangle or a curve matching the reinforcing member.

[0015] Preferably, in the butterfly-shaped optical cable for improving additional attenuation, the cross-section of the optical unit is circular, the cross-section of the reinforcing member is circular, and the cross-section of the buffer portion is the double-circular external tangent region of the cross-section of the optical unit and the cross-section of the reinforcing member.

[0016] Preferably, the compressive strength of the buffer portion of the improved butterfly optical cable is between 0.5 and 5 MPa, more preferably between 1 and 3 MPa, and its elastic modulus is between 1 and 20 MPa, more preferably between 3 and 4 MPa.

[0017] Preferably, the material of the buffer portion of the butterfly optical cable that improves additional attenuation is foamed polyethylene with a foaming degree of 33% to 90%, preferably 40% to 75%.

[0018] Preferably, the improved additional attenuation butterfly optical cable is characterized in that the sheath has an easy-tear opening, the tip of which points towards the optical unit.

[0019] According to another aspect of the present invention, a method for preparing the aforementioned butterfly optical cable with improved additional attenuation is provided, comprising the following steps:

[0020] (1) Threading: The light unit and the reinforcing member are threaded through the die head of the first extruder. The die head has a light unit through hole in the center and two symmetrical reinforcing members on both sides about the light unit through hole, so that the reinforcing members are symmetrically located on both sides of the light unit about the light unit.

[0021] (2) Extrusion foam layer: The first extruder extrudes the foam material melt through the die head and cools it between the light unit and the reinforcing member to form a buffer part with a porous structure; preferably, the buffer part is in close contact with at least one of the light unit and the reinforcing member, and preferably the buffer part is in close contact with the light unit and the reinforcing member;

[0022] (3) Extrusion of sheath: The buffer portion formed on the light unit and the reinforcing member passes through the die head of the second extruder together with the light unit and the reinforcing member, and the sheath material is extruded on its outside and cooled to form.

[0023] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0024] The butterfly-shaped optical cable provided by this invention has a buffer section set on the line connecting the geometric center of the optical unit and the geometric center of the reinforcement. The buffer section has a porous structure and has the ability to absorb sheath deformation. When the butterfly-shaped optical cable body is subjected to lateral pressure, it can reduce the inward compression of the optical unit caused by the sheath deformation, thereby reducing the increase in additional fiber attenuation caused by nailing vibration impact, lateral pressure and bending during the installation and wiring of the butterfly-shaped optical cable, thus improving the additional attenuation of the butterfly-shaped optical cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the sheath deformation of a butterfly-shaped optical cable under lateral pressure.

[0026] Figure 2 This is a schematic diagram of the butterfly optical cable structure for improving additional attenuation provided in Example 1;

[0027] Figure 3 This is a schematic diagram of the butterfly optical cable structure for improving additional attenuation provided in Example 2.

[0028] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the optical unit, 2 is the reinforcing member, 3 is the sheath, 4 is the buffer part, and 5 is the tear-resistant opening. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Butterfly-shaped optical cables typically have reinforcing members on both sides of the optical unit. These reinforcing members possess excellent mechanical properties, resistance to lateral pressure and tension, resulting in minimal deformation when subjected to lateral pressure, vibration, or bending. The sheath of the butterfly-shaped optical cable is generally made of high-molecular organic materials, exhibiting good elasticity, and thus showing significant deformation under lateral pressure, vibration, and bending. Due to its flat cross-sectional structure, the direction of external force applied to the cable body is generally perpendicular to the plane containing the center line of the reinforcing members. Figure 1 As shown. Due to the small deformation of the reinforcing member's positional stability, the deformation of the sheath under lateral pressure acts inward on the optical unit. After being squeezed, the optical unit experiences a significant increase in additional attenuation, and even if the sheath returns to its original shape, the additional attenuation still increases. During the installation of butterfly optical cables, impacts to the mounting clips, bending of the cabling, etc., inevitably bring lateral pressure. The deformation of the sheath causes inward compression of the optical unit, which is a significant reason for the increased additional attenuation of butterfly optical cables.

[0031] The butterfly optical cable with improved additional attenuation provided by the present invention includes an optical unit, a reinforcing member, and a sheath;

[0032] In a typical butterfly-shaped optical cable structure, the optical unit and reinforcing members are housed within the sheath. Reinforcing members, circular in shape, are located on both sides of the optical unit and are symmetrically arranged about the optical unit's axis. Their diameter is larger than the diameter of the fitted circle of the optical fiber glass portion within the optical unit. Because the diameter of the reinforcing members is generally larger than the diameter of the fitted circle of the optical fiber glass portion, lateral pressure generally does not directly act on the optical fiber glass portion within the optical unit. The significant cause of additional attenuation is the deformation of elastic components such as the sheath and the loose tube of the optical unit, which, under lateral pressure, exert pressure on the inner side of the optical fiber glass portion. Due to the good mechanical properties of the reinforcing members, their position remains largely unchanged due to sheath deformation. The deformation of the sheath and any loose tubes within the optical unit is most pronounced along the line connecting the geometric center of the optical unit and the geometric center of the reinforcing members, thus having the most significant impact on the increase in additional fiber attenuation within the optical unit. Typically, the butterfly-shaped optical cable sheath has a tear-resistant opening, with the tip of the tear pointing towards the optical unit, further concentrating sheath deformation on both sides of the optical unit. The distance from the tip of the tear seal to the optical unit is not strictly limited, and the depth of the tear seal in butterfly-shaped optical cables is typically around 0.3mm to 0.5mm. The depth design of the tear seal must ensure that the optical cable is easy to tear without affecting its mechanical and optical properties. If the depth is too shallow, it may be difficult to tear smoothly; if the depth is too deep, it may reduce the strength of the optical cable and increase the risk of damage during use.

[0033] A buffer section is provided on the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member; the buffer section has a porous structure. When the cable body plane is subjected to external impact, forming lateral pressure, the deformation generated by the sheath is absorbed by the buffer section on the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member, thereby reducing or avoiding the increase in additional fiber attenuation caused by the sheath deformation squeezing the optical unit inward.

[0034] Generally, the buffer portion is symmetrically arranged about the optical unit, that is, it is disposed on both sides of the optical unit, respectively, on the line connecting the geometric center of the two side reinforcements and the geometric center of the optical unit. The optical unit and / or the reinforcements are close to the buffer portion, with a distance of less than or equal to 0.2 mm. Preferably, the buffer portion is symmetrical about the line connecting the geometric center of the optical unit and the geometric center of the reinforcement. Considering the ease of manufacturing and the effect of absorbing sheath deformation, the buffer portion is preferably in close contact with at least one of the optical unit or reinforcements, so that when forming a porous buffer portion, it is attached to it, making it easier to form a predetermined cross-sectional shape and determine the position of the buffer portion.

[0035] The buffer portion is symmetrical about the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member. Its shape and dimensions on the side closer to the reinforcing member match the outer diameter of the reinforcing member, and its shape and dimensions on the side closer to the optical unit match the outer diameter of the optical unit. Since the deformation of the sheath is restricted by the reinforcing member and thus compresses the optical unit, a buffer portion is provided within the range of the common tangent between the reinforcing member and the optical unit. Its two ends match the outer diameters of the reinforcing member and the optical unit, respectively, effectively absorbing the deformation of the sheath and minimizing the impact on the mechanical strength of the sheath.

[0036] The compressive strength of the buffer section is between 0.5 and 5 MPa, preferably between 1 and 3 MPa, and its elastic modulus is between 1 and 20 MPa, preferably between 3 and 4 MPa. The preferred material is foamed polyethylene, with a foaming degree of 33% to 90%, preferably 40% to 75%. The cells in the foamed polyethylene are typically approximately spherical or polyhedral in shape, with over 90% of the cell size distributed between 1 μm and 200 μm, 85% of the cell size distributed between 2 μm and 100 μm, and 80% of the cell size distributed between 5 μm and 60 μm.

[0037] The present invention provides a method for preparing a butterfly-shaped optical cable with improved additional attenuation, comprising the following steps:

[0038] (1) Threading: The light unit and the reinforcing member are threaded through the die head of the first extruder. The die head has a light unit through hole in the center and two symmetrical reinforcing members on both sides about the light unit through hole, so that the reinforcing members are symmetrically located on both sides of the light unit about the light unit.

[0039] (2) Extrusion foam layer: The first extruder extrudes the foam material melt through the die head and cools it between the light unit and the reinforcing member to form a buffer part with a porous structure; preferably, the buffer part is in close contact with at least one of the light unit and the reinforcing member; preferably, the buffer part is in close contact with the light unit and the reinforcing member, so that the reinforcing member, the buffer part and the light unit form a whole, and the buffer part is formed in a more precise way with a preset cross-sectional shape and in a preset position.

[0040] (3) Extrusion of sheath: The buffer portion formed on the light unit and the reinforcing member passes through the die head of the second extruder together with the light unit and the reinforcing member, and the sheath material is extruded on its outside and cooled to form.

[0041] The following is an example:

[0042] Example 1

[0043] The butterfly optical cable provided in this embodiment improves additional attenuation, such as Figure 2 The image shows a miniaturized butterfly cable with a cross-section of 1.6mm × 2.1mm, comprising an optical unit, a reinforcing member, and a sheath; wherein:

[0044] The optical unit is a single-core optical unit, i.e., an optical fiber with a diameter of 250μm;

[0045] The reinforcing component is an FRP (fiberglass reinforced plastic) component with an outer diameter of 0.4 mm;

[0046] The sheath is made of HDPE material; the sheath has an easy-tear opening, the tip of which points towards the optical unit, with a depth of 0.3mm.

[0047] The cross-section of the buffer section is a near-isosceles triangle, with its central axis symmetrical to the line connecting the geometric center of the optical unit and the geometric center of the reinforcing member. The end of the buffer section closest to the reinforcing member is a curve that matches the reinforcing member. The buffer section is in close contact with the reinforcing member, and the distance between it and the optical unit is 0.1 mm. The buffer section is made of foamed polyethylene with a foaming degree of 75%, a compressive strength of 1 MPa, and an elastic modulus of 3 MPa.

[0048] The butterfly-shaped optical cable with improved additional attenuation provided in this embodiment is prepared by the following method:

[0049] (1) Threading: The optical fiber and the FRP reinforcement are threaded through the die head of the first extruder. The die head has a central optical unit through hole and two symmetrical reinforcements on both sides about the optical unit through hole, so that the reinforcements are symmetrically located on both sides of the optical unit about the optical unit.

[0050] (2) Extruded foamed layer: The first extruder extrudes the foamed polyethylene melt through the die head mold, and cools it between the optical unit and the reinforcing member to form a buffer part with a porous structure. It is then attached to the reinforcing member and cooled to form the buffer part. Since optical fiber is used as the optical unit, the buffer part is not easy to directly contact the optical fiber. Therefore, the buffer part is attached to the reinforcing member and there is a certain distance between it and the optical fiber.

[0051] (3) Extrusion sheath: The buffer portion formed on the light unit and the reinforcement is passed through the die head of the second extruder together with the light unit and the reinforcement, and high-density polyethylene sheath material is extruded on its outside and cooled and formed.

[0052] Example 2

[0053] The butterfly optical cable provided in this embodiment improves additional attenuation, such as Figure 3 The image shows a standardized butterfly cable with a cross-section of 2.0mm × 3.0mm, comprising an optical unit, a reinforcing member, and a sheath; wherein:

[0054] The optical unit is a single-core optical unit, specifically a single-core tight-buffered optical fiber with an outer diameter of 0.6 mm.

[0055] The reinforcing member is a steel wire reinforcing member with a total cross-sectional diameter of 0.5mm;

[0056] The sheath is made of HDPE material; the sheath has an easy-tear opening, the tip of which points towards the optical unit, with a depth of 0.3mm.

[0057] The optical unit has a circular cross-section, the reinforcing member has a circular cross-section, and the buffer portion has a cross-section that is the outer tangent of a double circle with a diameter of 0.2 mm, concentric with the cross-section of the optical unit outside the optical unit. The cross-sections of the optical unit, the buffer portion, and the reinforcing member form a bowtie shape. The buffer portion is in close contact with the reinforcing member and the optical unit. The buffer portion is made of foamed polyethylene with a foaming degree of 45%, a compressive strength of 3 MPa, and an elastic modulus of 4 MPa.

[0058] The butterfly-shaped optical cable with improved additional attenuation provided in this embodiment is prepared by the following method:

[0059] (1) Threading: Pass the sleeve light unit and the FRP reinforcement through the die head of the first extruder. The die head has a light unit through hole in the center and two symmetrical reinforcements on both sides about the light unit through hole, so that the reinforcements are symmetrically located on both sides of the light unit about the light unit.

[0060] (2) Extruded foamed layer: The first extruder extrudes the foamed polyethylene melt through the die head mold, and cools it between the light unit and the reinforcing member to form a buffer part with a porous structure. It is attached to the reinforcing member and the sleeve light unit and then cooled to form the buffer part. The reinforcing member, the buffer part and the sleeve light unit form a whole, with a stable relative position, and the shape of the buffer part is easy to control.

[0061] (3) Extrusion sheath: The buffer portion formed on the light unit and the reinforcement is passed through the die head of the second extruder together with the light unit and the reinforcement, and high-density polyethylene sheath material is extruded on its outside and cooled and formed.

[0062] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A butterfly optical cable with improved additional attenuation, characterized in that: including an optical unit, a reinforcement member, and a sheath; The optical unit and the reinforcement are received in the sheath; Reinforcements are provided on both sides of the optical unit, and the reinforcements are circular, and their diameters are larger than the diameters of the optical fiber fitting circles in the optical unit; A buffer portion is provided on the line connecting the geometric center of the optical unit and the geometric center of the reinforcement member; The buffer portion has a porous structure.

2. The butterfly optical cable with improved additional attenuation as claimed in claim 1, characterized in that: The reinforcing member is symmetrically arranged with respect to the axis of the optical unit, and the buffer portion is symmetrically arranged with respect to the axis of the optical unit.

3. The butterfly optical cable with improved additional attenuation as claimed in claim 1, characterized in that: The optical unit and / or the reinforcing member are close to the buffer portion, and the distance therebetween is less than or equal to 0.2 mm.

4. The butterfly optical cable with improved additional attenuation as claimed in claim 3, characterized in that: The buffer portion is symmetrical about the line connecting the geometric center of the light unit and the geometric center of the reinforcement, and its shape and size on the side close to the reinforcement match the outer diameter of the reinforcement, and its shape and size on the side close to the light unit match the outer diameter of the light unit.

5. The butterfly optical cable with improved additional attenuation as claimed in claim 4, characterized in that: The cross section of the buffer portion is an isosceles triangle or a quasi-isosceles triangle, wherein the axis coincides with the line connecting the geometric center of the light unit and the geometric center of the reinforcement, and the end close to the reinforcement is the base of the isosceles triangle or a curve matching the reinforcement.

6. The butterfly optical cable with improved additional attenuation as claimed in claim 4, characterized in that: The cross section of the reinforcement is circular, the cross section of the buffer portion includes a double circular circumscribed area of ​​the optical fiber fitting circle outside the optical unit and the reinforcement and the cross section of the reinforcement, and the cross section of the buffer portion is within the double circumscribed area of ​​the cross section of the optical unit and the reinforcement.

7. The butterfly optical cable with improved additional attenuation as claimed in claim 1, characterized in that: The compressive strength of the buffer part is between 0.5 and 5 MPa, preferably between 1 and 3 MPa, and the elastic modulus is between 1 and 20 MPa, preferably between 3 and 4 MPa.

8. The butterfly optical cable with improved additional attenuation as claimed in claim 7, characterized in that: The material of the buffer part is foamed polyethylene, and the foaming degree thereof is 33% to 90%, preferably 40% to 75%.

9. The butterfly optical cable with improved additional attenuation according to any one of claims 1 to 8, characterized in that: The sheath has an easy-tear opening, and the tip of the easy-tear opening points toward the light unit.

10. The method for preparing a butterfly optical cable with improved additional attenuation according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Threading: passing the light unit and the reinforcement through the die head of the first extruder, wherein the die head has a light unit through hole in the center and two through holes on both sides symmetrical to the light unit through hole, so that the reinforcement is symmetrically located on both sides of the light unit with respect to the light unit; (2) Extrusion foaming layer: The first extruder extrude the foaming material melt through the die head, and cools it between the light unit and the reinforcement to form a buffer portion with a porous structure; preferably, the buffer portion is in close contact with at least one of the light unit and the reinforcement, and preferably the buffer portion is in close contact with the light unit and the reinforcement; (3) Extrusion of sheath: The buffer portion formed on the optical unit and the reinforcement member is passed through the die head of the second extruder together with the optical unit and the reinforcement member, and the sheath material is extruded from the outside and cooled to form.

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