1. A butterfly-shaped optical cable is characterized by comprising an optical fiber, a resin layer, a first protective layer, a second protective layer, a sheath, a reinforcing element and a mark strip; the optical fiber, the resin layer, the first protective layer and the second protective layer are sequentially sleeved along the radial direction to form an optical fiber unit; the two groups of the reinforcing elements are symmetrically arranged on two opposite sides of the optical fiber unit, the sheath covers and fixes the reinforcing elements and the optical fiber unit, the reinforcing elements are made of insulating materials, the breaking force of the reinforcing elements is 500-600N, the identification strip is arranged on one side of the outer surface of the sheath along the axis of the butterfly-shaped optical cable, the color of the identification strip is different from that of the sheath, and the identification strip is made of luminous materials.

2. The butterfly cable of claim 1, wherein said sheath is further grooved on opposite sides of said sheath.

3. The butterfly-shaped optical cable of claim 1, wherein the overall breaking force of the butterfly-shaped optical cable is 1000-1500N, the wall thickness of the sheath is 0.6mm ± 0.1mm, and the width of the identification strip is 1.2 ± 0.2 mm.

4. The butterfly-shaped optical cable of claim 1, wherein a shrinkage ratio of the first protective layer is less than 1%.

5. The butterfly cable of claim 1, wherein the second protective layer is formed by co-extruding the first material and the second material in a predetermined mass ratio; the first material comprises a PBT material and the second material comprises a PC material.

6. A butterfly-shaped optical cable preparation method is used for preparing the butterfly-shaped optical cable of any one of claims 1 to 5, and comprises the following steps:

drawing the optical fiber into a coating die, coating a resin layer on the surface of the optical fiber by the coating die, and heating and curing the resin layer by a curing oven;

placing the optical fiber coated with the resin layer after curing into a first extrusion molding die, and extruding a first protective layer on the surface of the resin layer by the first extrusion molding die to form a core optical fiber;

drawing the core optical fiber to a second extrusion molding die, and extruding a second protective layer on the surface of the core optical fiber by the second extrusion molding die according to a preset mass ratio to form an optical fiber unit;

optical fiber unit and intensive component get into in third extrusion molding mould and the fourth extrusion molding mould jointly, third extrusion molding mould with fourth extrusion molding mould extrusion molding sheath and sign strip simultaneously, sheath cladding optical fiber unit and intensive component, the power of rupture of intensive component is 500 ~ 600N, sign strip extrusion molding is in one side of sheath outward appearance, the material of sign strip is the material that can give out light.

7. The method for preparing a butterfly-shaped optical cable according to claim 6, wherein the material of the first protective layer includes a halogen-free flame retardant material, and the step of extruding the first protective layer on the surface of the resin layer by the first extrusion mold includes:

after the first protective layer is extruded on the surface of the resin layer, the core optical fiber is sequentially drawn to a first water tank and a second water tank, the water temperature of the first water tank is 40 +/-5 ℃, and the water temperature of the second water tank is 20-30 ℃.

8. The method for manufacturing a butterfly-shaped optical cable according to claim 6, wherein the step of extruding the second protective layer on the surface of the core optical fiber by the second extrusion die from the first material and the second material in a predetermined mass ratio includes:

simultaneously delivering the first material and the second material at the second extrusion die;

and after the core optical fiber covered with the second protective layer comes out of the second extrusion molding die, the core optical fiber is sequentially cooled by a third water tank and a fourth water tank, wherein the water temperature of the third water tank is 70 +/-5 ℃, and the water temperature of the fourth water tank is 20-30 ℃.

9. The method for preparing the butterfly-shaped optical cable according to claim 8, wherein the first material comprises a PBT material, the second material comprises a PC material, and the mass ratio of the first material to the second material is 1: 2.

10. The method of manufacturing a butterfly-shaped optical cable according to claim 6, wherein the step of extruding a sheath by the third extrusion die to cover the optical fiber unit and the strength member includes:

the optical fiber unit is arranged in a die core of the third extrusion molding die, and the reinforcing element is arranged between the die core and a die sleeve of the third extrusion molding die;

and adjusting the paying-off tension of the optical fiber unit to be 3-7N, and adjusting the directional tension of the reinforcing element to be 12-18N, wherein the reinforcing element is arranged in parallel to the optical fiber unit.

Background

The butterfly-shaped optical cable is overhead to the home for wiring, and is mostly led into each home from a telegraph pole; however, most telegraph poles are scattered on two sides of a road in rural areas, and many telegraph poles can not reach the height standard of the telegraph poles, so that butterfly cables are led into a house from the telegraph poles and tend to cross the road, the butterfly cables are in danger of being hit by ultrahigh vehicles, and the butterfly cables are particularly prominent at night. Because butterfly cable all is the metal reinforcing component, receives the vehicle striking back, and all parts of optical cable are because of can not all brittle failure, and the vehicle striking can lead to the optical cable to drag the wire pole directly down, causes whole line pole circuit paralysis.

Disclosure of Invention

In view of the above situation, the present application provides a butterfly-shaped optical cable and a manufacturing method thereof, which use a low breaking force strength member to make the whole optical cable brittle after being impacted by a strong force, so as to avoid the problem that the whole optical cable is pulled down over the whole line rod without breaking after being impacted by a strong force, thereby causing a greater damage to the whole optical cable line. The sheath outward appearance of optical cable still sets up the one deck sign strip that can give out light, and under the environment at night, light shines and can obviously discern, promotes the security performance of optical cable.

The embodiment of the application provides a butterfly-shaped optical cable which comprises an optical fiber, a resin layer, a first protective layer, a second protective layer, a sheath, a reinforcing element and a mark strip; the optical fiber, the resin layer, the first protective layer and the second protective layer are sequentially sleeved along the radial direction to form an optical fiber unit; the two groups of the reinforcing elements are symmetrically arranged on two opposite sides of the optical fiber unit, the sheath covers and fixes the reinforcing elements and the optical fiber unit, the reinforcing elements are made of insulating materials, the breaking force of the reinforcing elements is 500-600N, the identification strip is arranged on one side of the outer surface of the sheath along the axis of the butterfly-shaped optical cable, the color of the identification strip is different from that of the sheath, and the identification strip is made of luminous materials.

In some embodiments, the sheath is further provided with grooves on opposite sides thereof.

In some embodiments, the material of the sheath comprises a polyethylene material, and the overall breaking force of the butterfly-shaped optical cable is 1000-1500N.

In some embodiments, the wall thickness of the sheath is 0.6mm + 0.1mm and the width of the marker strip is 1.2 + 0.2 mm.

In some embodiments, the butterfly-shaped optical cable is insulated for 2 hours in an environment at 110 ℃, and the shrinkage ratio of the first protective layer is less than 1%.

In some embodiments, the second protective layer is formed by co-extruding the first material and the second material in a predetermined mass ratio; the first material comprises a PBT material and the second material comprises a PC material. The embodiment of the application further provides a butterfly-shaped optical cable preparation method, which is used for preparing the butterfly-shaped optical cable in the embodiment, and the butterfly-shaped optical cable preparation method comprises the following steps:

drawing the optical fiber into a coating die, coating a resin layer on the surface of the optical fiber by the coating die, and heating and curing the resin layer by a curing oven;

placing the optical fiber coated with the resin layer after curing into a first extrusion molding die, and extruding a first protective layer on the surface of the resin layer by the first extrusion molding die to form a core optical fiber;

drawing the core optical fiber to a second extrusion molding die, and extruding a second protective layer on the surface of the core optical fiber by the second extrusion molding die according to a preset mass ratio to form an optical fiber unit;

optical fiber unit and intensive component get into in third extrusion molding mould and the fourth extrusion molding mould jointly, third extrusion molding mould with fourth extrusion molding mould extrusion molding sheath and sign strip simultaneously, sheath cladding optical fiber unit and intensive component, the breaking force of intensive component is 500 ~ 600N, sign strip extrusion molding is in one side of sheath outward appearance, the material of sign strip is the material that can give out light.

In some embodiments, the material of the first protective layer includes a halogen-free flame retardant material, and the step of extruding the first protective layer on the surface of the resin layer by the first extrusion die includes:

after the first protective layer is extruded on the surface of the resin layer, the core optical fiber is sequentially drawn to a first water tank and a second water tank, the water temperature of the first water tank is 40 +/-5 ℃, and the water temperature of the second water tank is 20-30 ℃.

In some embodiments, the step of extruding a second protective layer of a first material and a second material in a predetermined mass ratio on the surface of the core optical fiber by the second extrusion die comprises:

simultaneously delivering the first material and the second material at the second extrusion die;

and after the core optical fiber covered with the second protective layer comes out of the second extrusion molding die, the core optical fiber is sequentially cooled by a third water tank and a fourth water tank, wherein the water temperature of the third water tank is 70 +/-5 ℃, and the water temperature of the fourth water tank is 20-30 ℃.

In some embodiments, the first material comprises a PBT material, the second material comprises a PC material, and the mass ratio of the first material to the second material is 1: 2.

In some embodiments, the material of the reinforcing element is an insulating material, and the diameter of the reinforcing element is 0.6-1.0 mm.

In some embodiments, the step of extruding a jacket over the optical fiber unit and the strength member with the third extrusion die comprises:

the optical fiber unit is arranged in a die core of the third extrusion molding die, and the reinforcing element is arranged between the die core and a die sleeve of the third extrusion molding die;

and adjusting the paying-off tension of the optical fiber unit to be 3-7N, and adjusting the directional tension of the reinforcing element to be 12-18N, wherein the reinforcing element is arranged in parallel to the optical fiber unit.

According to the butterfly-shaped optical cable and the preparation method thereof, the reinforcing element with low breaking force is adopted in the optical cable, so that the condition that all parts of the optical cable are simultaneously brittle-broken within the range of 1000N-1500N force value after the optical cable is impacted by external force is ensured, and the problem of secondary damage caused by the fact that the optical cable is not broken after the optical cable is impacted by strong force is solved. The sheath surface of the optical cable is also provided with a luminous identification strip, so that the light irradiation can be obviously identified in the night environment, and the safety performance of the optical cable is improved

Drawings

Fig. 1 is a schematic cross-sectional view of a butterfly-shaped fiber optic cable in one embodiment.

Fig. 2 is a flow diagram of a method of making a butterfly-shaped fiber optic cable in one embodiment.

Description of the main element symbols:

butterfly-shaped optical cable	10
		Optical fiber	1
Resin layer	2
		First protective layer	3
Second protective layer	4
		Protective sleeve	5
Concave part	51
		Reinforcing element	6
Identification strip	7

The specific implementation mode is as follows:

the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting, as the term "or/and" as used herein is inclusive of any and all combinations of one or more of the associated listed items.

Referring to fig. 1 and 2, in one embodiment, a method for manufacturing a butterfly-shaped optical cable 10 includes the following steps:

step S1: and drawing the optical fiber into a coating die, coating the surface of the optical fiber with a resin layer by the coating die, and heating and curing the resin layer by a curing oven.

Specifically, step S1 is a process of coating the resin layer 2 on the optical fiber 1 and curing the resin layer 2. Optical fiber 1 is first drawn from a pay-off reel through a guide wheel into a coating die of a cable manufacturing apparatus (not shown). In the process of drawing the optical fiber 1, the drawing tension of the drawing frame is adjusted to 70 to 90g, preferably 80g, so that the optical fiber 1 is not excessively loosened during drawing and is not broken due to excessive tension. The die orifice of the coating die is connected to a coating material container in which a resin material is previously stored, through a connecting pipe. The thickness of the resin layer 2 coated on the outer surface of the optical fiber 1 is controlled by adjusting a valve of a barometer on a coating material container and selecting a coating die.

After the resin layer 2 is coated on the outer surface of the optical fiber 1, the optical fiber comes out of the coating die and enters a curing oven of optical cable manufacturing equipment to heat and cure the resin layer 2. In the embodiment of the application, the curing oven is heated by an LED lamp, the length of the heating area is 100 cm-120 cm, and the viscosity of the surface curing of the resin layer 2 is controlled by adjusting the power of a lamp tube of the curing oven. The heating temperature can be adjusted by controlling the power of the LED lamp tube, and the heating temperature is 140-160 ℃, and is preferably 150 ℃. The optical fiber 1 has an outer diameter of 0.4 to 0.6mm, preferably 0.5mm, after being coated with the resin layer 2.

In the examples of the present application, the resin layer 2 is a transparent material, wherein the resin layer 2 is typically characterized by a material viscosity of about 2.2 mps; tensile force about 8MPa, elongation force about 20MPa, and equilibrium modulus about 11 MPa. The resin layer 2 is used to coat the optical fiber 1, which is advantageous for increasing the protective performance of the optical fiber 1.

Step S2: the optical fiber coated with the resin layer after curing is put into a first extrusion molding die which extrudes a first protective layer on the surface of the resin layer to form a core optical fiber.

Specifically, the outer surface of the optical fiber 1 is coated with the resin layer 2 and then enters a first extrusion mold of the cable manufacturing apparatus. In the examples of the present application, the first extrusion die employs a tube extrusion die. The first extrusion die extrudes the first protective layer 3 on the surface of the resin layer 2 while the optical fiber coated with the resin layer 2 passes through the first extrusion die, forming a core optical fiber. The material of the first protective layer 3 is a halogen-free flame retardant material, including but not limited to a flame retardant polyolefin material. After the first protective layer 3 extrusion molding is on the resin layer 2 surface, the core optic fibre is sent to the traction wheel after the basin cooling to it is reserve to carry out the rolling to the core optic fibre. Along the traction direction of the core optical fiber, the water tank comprises a first water tank and a second water tank which are sequentially arranged, the water temperature of the first water tank is controlled to be 40 +/-5 ℃, and the temperature of the second water tank is 20-30 ℃ at normal temperature, so that the temperature of the first protection layer 3 formed by extrusion molding is gradually reduced in the water tank, and the problem that the first protection layer 3 is broken or poor in forming quality due to temperature shock is solved. After the core optical fiber is drawn out from the water tank, the outer diameter of the first protective layer 3 is adjusted by adjusting the mold, so that the roundness precision of the first protective layer 3 is improved, and the outer diameter dimension of the core optical fiber is controlled to be 0.9 +/-0.05 mm.

Step S3: the core optical fiber is drawn to a second extrusion die, and the second extrusion die extrudes a second protective layer on the surface of the core optical fiber by the first material and the second material according to a preset mass ratio to form an optical fiber unit.

Specifically, the extrusion molding machine head for extruding the second protective layer 4 selects a double-layer extrusion molding machine head, the first material and the second material are simultaneously conveyed to the second extrusion molding die, so that the second extrusion molding die extrudes the first material and the second material on the appearance of the core optical fiber according to the preset mass proportion, and the second protective layer is formed on the appearance of the core optical fiber. And (3) putting the prepared core optical fiber into a core optical fiber pay-off rack, adjusting the pay-off tension of the core optical fiber to be 3N, then drawing the core optical fiber from the pay-off rack to an extrusion molding machine head through a guide wheel, and extruding a second protective layer 4 on the outer surface of the core optical fiber under the combined action of the extrusion molding machine head and a second extrusion molding die to form an optical fiber unit. And after the core optical fiber covered with the second protective layer 4 comes out of the second extrusion molding die, the core optical fiber passes through a water tank to a traction disc, and the optical fiber unit is wound up. Along the traction direction of the optical fiber, the water tank comprises a third water tank and a fourth water tank which are sequentially arranged, the water temperature of the third water tank is controlled to be 70 +/-5 ℃, and the temperature of the fourth water tank is controlled to be 20-30 ℃ at normal temperature so as to avoid the temperature shock of the second protective layer 4 in a molten state from affecting the forming quality of the second protective layer 4. After the core optical fiber coated with the second protective layer 4 is drawn out from the water tank, the outer diameter of the second protective layer 4 is adjusted by adjusting the mold, so that the outer diameter of the optical fiber unit is controlled to be 1.9 +/-0.1 mm.

Further, too large or too small of the excess length affects the transmission performance of the optical fiber. For example, in a low-temperature environment, the second protective layer is shortened, the optical fiber is not changed, the optical fiber is bent in the second protective layer, so that the bending loss of the optical fiber is increased, and the low-temperature performance of the optical fiber is deteriorated; when the second protective layer is stretched in a high-temperature environment, the optical fiber is not changed, the optical fiber is stretched and stressed in the second protective layer, the transmission performance of the optical fiber is affected, and the optical fiber is broken when the optical fiber is serious. In order to avoid the influence of the excess fiber length on the transmission performance of the optical fiber, the excess fiber length of the core optical fiber is controlled to be 0 to 0.6 per thousand during the extrusion of the second protective layer 4 in the embodiment of the present application.

The first material includes, but is not limited to, a PBT material and the second material includes, but is not limited to, a PC material. The PBT material has excellent bending resistance and high tensile strength; the PC material has excellent low shrinkage performance. In the embodiment of the present application, the first material and the second material are formed into the second protective layer 4 by extrusion molding in a mass ratio of 1:2, which ensures excellent bending property of the second protective layer while also reducing shrinkage property of the second protective layer, ensuring stable property of attenuation of the core optical fiber in the second protective layer.

Step S4: the optical fiber unit and the strength member are jointly entered into a third extrusion die and a fourth extrusion die, and the third extrusion die extrudes a sheath to coat the optical fiber unit and the strength member. The optical fiber unit with the parallel and interval setting of reinforcing element, fourth extrusion molding mould form the butterfly-shaped optical cable at the outside extrusion molding identification strip of one side of sheath.

Specifically, the third extrusion molding mould with fourth extrusion molding mould extrusion molding simultaneously the sheath reaches the sign strip, sheath cladding optical fiber unit and reinforcing element, reinforcing element's breaking force is 500 ~ 600N, sign strip extrusion molding is in one side outward appearance of sheath, the material of sign strip is the material that can give out light.

The third extrusion die is an extrusion type extrusion die, and the optical fiber unit and the reinforcing element 6 jointly enter the third extrusion die so that the sheath 5 is extruded on the outer surfaces of the optical fiber unit and the reinforcing element 6, thereby fixing the optical fiber unit and the reinforcing element 6. Wherein the optical fibre unit is arranged in the core of a third extrusion die and the strength member 6 is arranged between the core and the jacket of the third extrusion die. In the embodiment of the present application, two sets of strength members 6 are symmetrically disposed on opposite sides of the optical fiber unit. In the extrusion molding process of the sheath 5, the optical fiber unit and the reinforcing elements 6 are paid off by adopting a pay-off rack, and during paying off, the two reinforcing elements 6 are arranged on two opposite sides of the optical fiber unit in parallel. The paying-off tension of the optical fiber unit is adjusted to 3-7N, preferably 5N, and the paying-off tension of the reinforcing member 6 is set to 12-18N, preferably 15N, according to the material properties of the optical fiber unit and the reinforcing member 6, so that the optical fiber unit and the reinforcing member 6 are kept relatively parallel when paying off, and the optical fiber unit or the reinforcing member 6 is not loosened due to too small tension or damaged due to too large tension. The optical fiber unit coated with the sheath 5 and the reinforcing element 6 are drawn out from the third extrusion molding die, cooled by a water tank, and drawn into a take-up reel for winding and standby.

In the extrusion molding process of the sheath 5, along the optical fiber traction direction, the water tank comprises a fifth water tank and a sixth water tank which are sequentially arranged, wherein the fifth water tank is a hot water tank, the water temperature is 60 +/-5 ℃, the sixth water tank is a normal temperature water tank, and the water temperature is 20-30 ℃. The sheath 5 in the molten state is cooled and solidified through the hot water tank and the cold water tank in sequence, so that the sheath 5 is prevented from being suddenly cooled to influence the forming quality of the sheath 5. When 5 extrusion moldings of sheath, can also ensure that the sheath 5 surface that the extrusion molding formed is smooth, level and smooth through adjusting relative position between mold core and the die sleeve in the third extrusion molding mould, reinforcing element 6 cladding is in sheath 5, and the wall thickness of sheath 5 is even, and the external diameter control of sheath 5 is in the required scope.

Further, the material of the sheath 5 includes, but is not limited to, a low breaking force high density polyethylene material. After extrusion molding, the elongation at break strain of the sheath 5 is 750%, and the low breaking force performance of the sheath can ensure that the whole optical cable can be completely brittle-broken between 1000N and 1500N.

The reinforcing element 6 is made of insulating materials, and safety performance of the broken optical cable is improved. In the embodiments of the present application, the reinforcing element 6 includes, but is not limited to, a non-metallic composite rod. The diameter of the composite rod is 0.6-1.0mm, the elastic modulus is 80-90 Gpa, and the breaking force is 500-600N, so that the requirement of low breaking force of the optical cable is met.

The fourth extrusion molding die is connected with the color bar extruding machine, and colored extrusion molding materials are added into the color bar extruding machine according to a certain proportion. When the optical cable enters the fourth extrusion die, the extrusion machine adjusts the extrusion width of the identification strip 7 outside the sheath 5 by adjusting the extrusion amount in the fourth extrusion die. In the embodiment of the application, the width of the identification strip 7 is controlled to be 1.2 +/-0.2 mm, the material of the identification strip 7 is a luminescent material, and the material of the identification strip 7 and the material of the sheath 5 have good compatibility, so that the identification strip 7 can be embedded on the surface of the sheath 5 to reduce the problem of the falling-off of the identification strip.

Step S5: and pulling the butterfly-shaped optical cable to a traction wheel, adjusting take-up tension and rolling the butterfly-shaped optical cable.

Specifically, the identification strip 7 is extruded, after the outer diameter wall thickness and the surface quality of the sheath 5 are adjusted, the butterfly-shaped optical cable 10 is drawn to a traction wheel, the take-up tension of the traction wheel is adjusted to control the take-up tension to be 25-35N, preferably 30N, the butterfly-shaped optical cable 10 is taken up and wound by the traction wheel so as to be stored for later use, and the preparation process of the butterfly-shaped optical cable 10 is completed.

The butterfly-shaped optical cable 10 manufactured by the steps has the overall cable diameter of about 5.6(+/-0.2) × 3.4(+/-0.2) mm, the cable weight of about (16 +/-5%) kg/km, the overall breaking force of the optical cable of 1000N-1500N, and the overall medium structure of the optical cable. Compared with the conventional self-supporting overhead butterfly-shaped optical cable, the butterfly-shaped optical cable 10 prepared by the method is light in weight, adopts the high-modulus non-metal composite rod to replace a steel wire reinforcing member, is provided with the luminous color strip identification line on the outer surface of the sheath, greatly improves the safety performance of the optical cable, has the advantages of lightning protection, electricity prevention and the like, and meets the application requirements of various occasions.

Referring to fig. 1 again, the embodiment of the present application further provides a butterfly-shaped optical cable 10, where the butterfly-shaped optical cable 10 is manufactured by the method for manufacturing the butterfly-shaped optical cable according to the embodiment. The butterfly-shaped optical cable 10 includes an optical fiber 1, a resin layer 2, a first protective layer 3, a second protective layer 4, a sheath 5, a reinforcing member 6, and a marker strip 7. The optical fiber 1, the resin layer 2, the first protective layer 3 and the second protective layer 4 are sequentially sleeved along the radial direction to form an optical fiber unit. Two groups of reinforcing elements 6 are symmetrically arranged at two opposite sides of the optical fiber unit, and the sheath 5 coats and fixes the reinforcing elements 6 and the optical fiber unit. The identification strip 7 is arranged on one side of the outer surface of the sheath 5.

In the embodiment of the present application, the outer diameter dimension of the first protective layer 3 is 0.9 ± 0.05 mm; the outer diameter of the second protective layer 4 is 1.9 +/-0.1 mm; the reinforcing element 6 is a non-metal composite rod, the nominal diameter is 0.8mm +/-0.05 mm, and the breaking force is 550N +/-50N; the sheath 5 is made of black high-density low-breaking-force polyethylene, and the wall thickness is 0.6mm +/-0.1 mm; the marking strip 7 is made of red special luminescent material, and the width of the marking strip 7 is 1.2 +/-0.2 mm.

The core of the optical fiber 1 in the optical fiber unit is a core, and the type of the optical fiber 1 includes, but is not limited to, g.657a2 optical fiber, g.652d optical fiber, G657B3 optical fiber, and the like. In other embodiments, the number of cores of the optical fiber 1 may be multiple, which is sufficient for meeting design requirements, and the present application is not limited thereto. The resin layer 2 is a transparent material and is coated on the outer surface of the optical fiber 1. The resin layer 2 is typically characterized by a material viscosity of about 2.2 mps; tensile force about 8MPa, elongation force about 20MPa, and equilibrium modulus about 11 MPa. The use of the resin is advantageous for increasing the protective performance of the optical fiber 1 while enabling the optical fiber unit to have good stripping performance.

The material of the first protective layer 3 is a halogen-free flame retardant material, including but not limited to a flame retardant polyolefin material. In the embodiment of the present application, the tensile strength of the material of the first protection layer 3 reaches 18Mpa, and the toxicity index of the material is less than 0.5. In addition, the material of the first protection layer 3 also has good shrinkage performance, specifically, the butterfly-shaped optical cable 10 is insulated for 2 hours at 110 ℃, and the shrinkage proportion of the first protection layer 3 is less than 1%. Furthermore, the material of the first protection layer 3 also has excellent extrusion molding processability, so that the surface of the extruded first protection layer 3 is smooth and round, the attenuation performance is normal, and meanwhile, the first protection layer can be rapidly stripped for 2.5cm at one time, so that the construction efficiency of the optical cable is improved.

The second protective layer 4 is made by co-extruding the first material and the second material in a predetermined mass ratio. In an embodiment of the application, the first material comprises a PBT material, the second material comprises a PC material, and the second protective layer 4 is a PBT/PC co-extruded protective tube. The PBT material has excellent bending resistance and high tensile strength; the PC material has excellent low shrinkage performance. The second protective layer 4 is formed by co-extrusion molding of two materials according to the mass ratio of 1:2, so that the second protective layer 4 has excellent bending performance, the shrinkage performance of the second protective layer 4 is reduced, and the attenuation stability of the core optical fiber in the second protective layer 4 is ensured. The PBT/PC co-extrusion protection tube and the low-breaking-force reinforcing element 6 are jointly used in the optical cable 10, so that after the optical cable 10 is impacted by external force, all parts of the optical cable can be integrally brittle-broken within a force value range of 1000N-1500N, and the problem that after the optical cable is impacted by strong force, the optical cable is pulled to the whole line rod without breaking, and the whole optical cable line is damaged greatly is avoided.

The material of the sheath 5 includes, but is not limited to, a high density polyethylene material having a low breaking force. The elongation at break strain of the sheath 5 is 750%, and the butterfly-shaped optical cable 10 can be completely brittle-broken when the whole butterfly-shaped optical cable 10 is stressed between 1000N and 1500N due to the low breaking force performance of the sheath 5, besides meeting the ultraviolet resistance and oxidation resistance and ensuring the light resistance of the overhead optical cable in the operation process.

In the optical cable installation use, in order to make things convenient for sheath 5 to open and shell, the relative both sides of sheath 5 still are equipped with the recess respectively. The groove achieves the size appearance of the optical cable by adjusting the structure and the size of the extrusion molding die. Can follow during the construction and open bare-handed the optical cable of shelling along the notch, promote the efficiency of construction.

In the embodiment of the present application, two strength members 6 are embedded in the middle of the jacket in parallel symmetry along the cable axis, and the optical fiber unit is located between the two strength members 6. In other embodiments, the number of the reinforcing elements 6 may be more than two, which satisfies the design requirement. The reinforcing elements 6 are non-metal composite rods, and the diameter of each reinforcing element 6 is 0.6-1.0mm, preferably 0.8 mm. The elastic modulus of the reinforcing element 6 can reach 80-90 Gpa, the breaking force is 500-600N, the butterfly-shaped optical cable 10 meets the requirement of the aerial tensile fiber performance, the whole optical cable is completely brittle after the butterfly-shaped optical cable 10 is impacted by a strong force, and the optical cable material made of all-dielectric non-metal materials can also prevent lightning and electricity.

The identification strip 7 is used for identifying the optical cable, so that the construction efficiency is improved, and meanwhile, the identification strip is used for warning a user and improving the safety performance of the optical cable. The identification strip is linearly arranged along the axis of the butterfly-shaped optical cable 10 and is embedded on the surface of the sheath 5 in parallel. The material of the identification strip 7 comprises a luminescent material, and the material of the identification strip 7 has good compatibility with the material of the sheath 5, which is beneficial to reducing the problem of the identification strip 7 peeling off. In addition, the color of the identification strip 7 is different from that of the sheath 5, so that the butterfly-shaped optical cable 10 can be identified by observing the color of the identification strip 7 under night light irradiation.

Compared with a conventional self-supporting overhead butterfly-shaped optical cable, the butterfly-shaped optical cable provided by the application is innovative in structural design and forming process. The optical fiber unit adopts the core optical fiber to be placed in the PBT/PC second protective layer, so that the optical fiber is better protected, and the outdoor environment resistance is more outstanding. In addition, the optical cable uses high-modulus non-metal composite rod materials to replace steel wires as reinforcing elements, the whole weight of the optical cable is reduced, the optical cable is light and is more suitable for overhead laying, the whole optical cable can be completely brittle-broken between 1000N-1500N, and the problem that the optical cable is not broken after the optical cable is impacted by strong force from the middle, so that the line rod is pulled down is solved. The sheath outward appearance of optical cable has still extruded a can give out light sign strip, and under the environment at night, light shines can obviously to distinguish, promotes the security performance of optical cable. The whole all-dielectric structure of the optical cable can prevent lightning and electricity and has wider application occasions.

Although the present application has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the present application.