Shape sensing optical cable and manufacturing method thereof

Abstract

The invention relates to a shape sensing optical cable and a manufacturing method thereof. The shape sensing optical cable comprises an oil-filled sleeve, a reinforcing member, an inner sheath, a tight-buffered optical fiber and an outer sheath. A central optical fiber is arranged in the oil-filled sleeve, and ointment is arranged between the oil-filled sleeve and the central optical fiber. And a plurality of reinforcing pieces are spirally twisted on the oil-filled sleeve. The inner sheath is arranged on the outer side of the reinforcing piece, and a plurality of spiral pipe grooves are formed in the inner sheath at intervals along the circumferential side. The plurality of tight-buffered optical fibers are in one-to-one correspondence with the plurality of spiral tube grooves, and the tight-buffered optical fibers are embedded in the corresponding spiral tube grooves. And the outer sheath is directly arranged on the outer side of the inner sheath. The spiral tube groove is formed in the peripheral side of the inner sheath, and the tight-buffered optical fibers are spirally twisted and arranged in the spiral tube groove, so that the tight-buffered optical fibers are prevented from being damaged by external environment pressure; meanwhile, the inner sheath and the outer sheath are seamlessly connected, the outer sheath does not interfere with the tight tube optical fiber in the spiral tube groove in the extrusion molding and coating process, and a necessary movement space is provided for the tight tube optical fiber so as to reduce microbend loss.

Description

Technical Field

[0001] The present invention relates to the field of optical cable technology, and in particular to a shape-sensing optical cable and a manufacturing method thereof. Background Art

[0002] Existing ocean monitoring optical cables typically use loose-buffered fiber as the transmission medium. After stranding the outer layer with strength members, an inner sheath is extruded. Tight-buffered fiber is then wrapped around the inner sheath and secured with tape, and finally, the outer sheath material is extruded. In this structure, the wrapped tight-buffered fiber is not adequately protected and is susceptible to mechanical damage. Furthermore, the tight-buffered fiber placed in the outer sheath results in an uneven cable surface, increasing the outer diameter and material consumption. Summary of the Invention

[0003] The object of the present invention is to provide a shape-sensing optical cable and a manufacturing method, which can protect the tight-buffered optical fiber from damage by external environmental pressure by opening a spiral tube groove on the circumferential side of the inner sheath and spirally twisting the tight-buffered optical fiber into the spiral tube groove. At the same time, the outer sheath adopts seamless inner and outer sheaths, and the outer sheath will not interfere with the tight-buffered optical fiber in the spiral tube groove during the extrusion and coating process, and provides the tight-buffered optical fiber with the necessary activity space to reduce microbending loss.

[0004] To achieve the above object, according to a first aspect of the present invention, there is provided a shape-aware optical cable, characterized in that it comprises: An oil-filled casing, wherein a central optical fiber is disposed in the oil-filled casing, and grease is disposed between the oil-filled casing and the central optical fiber; a plurality of reinforcement members spirally twisted on the oil-filled casing; An inner sheath is arranged outside the reinforcement member, and a plurality of spiral tube grooves are spaced apart along the circumference of the inner sheath; A plurality of tight-buffered optical fibers correspond one-to-one to a plurality of the spiral tube grooves, and the tight-buffered optical fibers are embedded in the corresponding spiral tube grooves; The outer sheath is directly arranged outside the inner sheath.

[0005] Optionally, the central optical fiber and the tight-buffered optical fiber are grating optical fibers and / or polarization optical fibers.

[0006] Optionally, the overall density of the optical cable is 0.95-1.05 g / cm 3 between.

[0007] Optionally, the oil-filled sleeve is made of polybutylene terephthalate material.

[0008] Optionally, the reinforcement is made of fiber reinforced plastic material.

[0009] Optionally, the inner sheath and the outer sheath are both made of high-density polyethylene material.

[0010] According to a second aspect of the present invention, a method for manufacturing a shape-aware optical cable is provided, comprising the following steps: The polybutylene terephthalate raw material is heated and melted on the extruder, and then extruded through a tube drawing die to form an oil-filled sleeve. At the same time, the central optical fiber is inserted into the oil-filled sleeve, and the oil is injected and then cooled to shape. The optical fiber is melted with nylon material on an extruder and tightly wrapped through a tube drawing die, and then sized by vacuum to obtain a tight-cup optical fiber; Several fiber-reinforced plastic reinforcements are placed on the turntable of the cabling machine and spirally twisted on the prepared oil-filled casing. Subsequently, a high-density polyethylene inner sheath with spiral grooves is extruded through a special extrusion die. The prepared tight-buffered optical fibers are then embedded in the corresponding spiral grooves to form a cable core. The cable core is extruded with an outer sheath of high-density polyethylene material on an extruder to obtain the final shape-sensing optical cable.

[0011] Optionally, the outer diameter of the oil-filled casing is 2±0.1 mm, the sum of the diameter of the reinforcement and the thickness of the inner sheath is 7±0.3 mm, the thickness of the outer sheath is 2±0.2 mm, and the total outer diameter of the optical cable is 11±0.6 mm.

[0012] Optionally, the outer diameter of the tight-cup optical fiber is 0.9±0.05 mm, and the inner diameter of the spiral tube groove is 1.3±0.05 mm.

[0013] The beneficial effects of the present invention are as follows: by providing a spiral groove on the circumference of the inner sheath and helically stranding the tight-buffered optical fiber in the spiral groove, the tight-buffered optical fiber is protected from damage by external environmental pressure; at the same time, the inner and outer sheaths are seamlessly connected, and the outer sheath does not interfere with the tight-buffered optical fiber in the spiral groove during the extrusion coating process, and provides the tight-buffered optical fiber with necessary movement space to reduce microbending loss; The central fiber and tight-buffered fiber use grating fiber and polarization fiber. Utilizing the high sensitivity of grating fiber to respond to temperature and strain disturbances, and the precise control of light polarization state by polarization fiber, distributed multi-parameter monitoring of various physical parameters is achieved. Integrating both into the same optical cable significantly reduces reliance on external sensors and instruments, and improves the overall reliability and stability of the optical cable. The overall density of the optical cable is controlled to basically match the density of seawater, so that the optical cable obtains near-neutral buoyancy on the seabed and can be suspended in the seawater to meet monitoring requirements. This not only avoids tension concentration and unstable laying caused by lightness, but also prevents wear and breakage caused by excessive sedimentation.

[0014] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a shape-sensing optical cable according to an embodiment of the present invention; Figure 2 This is a schematic flow chart of a method for manufacturing a shape-sensing optical cable according to an embodiment of the present invention; In the figure: 1. Oil-filled casing; 2. Reinforcement member; 3. Inner sheath; 4. Tight-buffered optical fiber; 5. Outer sheath; 6. Center optical fiber; 7. Grease; 8. Spiral tube groove. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] See Figure 1 and Figure 2A shape-sensing optical cable and a manufacturing method shown in a preferred embodiment of the present application include an oil-filled casing 1, a strength member 2, an inner sheath 3, a tight-buffered optical fiber 4, and an outer sheath 5. A central optical fiber 6 is arranged in the oil-filled casing 1, and grease 7 is arranged between the oil-filled casing 1 and the central optical fiber 6. Several strength members 2 are spirally twisted on the oil-filled casing 1. The inner sheath 3 is arranged on the outside of the strength member 2, and a plurality of spiral tube grooves 8 are spaced apart along the circumferential side of the inner sheath 3. Several tight-buffered optical fibers 4 correspond one-to-one to the several spiral tube grooves 8, and the tight-buffered optical fibers 4 are embedded in the corresponding spiral tube grooves 8. The outer sheath 5 is directly arranged on the outside of the inner sheath 3.

[0020] According to the solution of the embodiment of the present invention, a spiral tube groove 8 is opened on the side of the inner sheath 3 and the tight-cup optical fiber 4 is spirally twisted and arranged in the spiral tube groove 8, so that the tight-cup optical fiber 4 is protected from damage by external environmental pressure; at the same time, the inner and outer sheaths 5 are seamlessly connected, and the outer sheath 5 will not interfere with the tight-cup optical fiber 4 in the spiral tube groove 8 during the extrusion coating process, and provides the tight-cup optical fiber 4 with the necessary activity space to reduce microbending loss.

[0021] The following is a detailed description with specific embodiments: The central optical fiber 6 and the tight-buffered optical fiber 4 are grating optical fibers and / or polarization optical fibers. The use of grating optical fibers and polarization optical fibers leverages the high sensitivity of grating optical fibers to temperature and strain disturbances, and the precise control of light polarization by polarization optical fibers, enabling distributed multi-parameter monitoring of various physical parameters. Integrating both into the same optical cable significantly reduces reliance on external sensors and instruments, and enhances the overall reliability and stability of the optical cable.

[0022] The overall density of the cable is 0.95-1.05g / cm 3 The overall density of the optical cable is controlled to basically match the density of seawater, so that the optical cable obtains near neutral buoyancy on the seabed and can be suspended in the seawater to meet monitoring requirements: it avoids tension concentration and unstable laying caused by lightness, and also prevents wear and breakage caused by excessive sedimentation. Specifically, in this embodiment, the overall density of the optical cable is 1.02g / cm 3 .

[0023] Specifically, the oil-filled casing 1 is made of polybutylene terephthalate (PBT). The reinforcement 2 is made of fiber-reinforced plastic (FRP). The inner sheath 3 and outer sheath 5 are both made of high-density polyethylene (HDPE). The PBT oil-filled casing 1 has high strength, high toughness, and excellent chemical corrosion resistance, and can withstand the mechanical compressive stress and dielectric corrosion of the seabed environment. The grease 7 filled in the oil-filled casing 1 reduces friction between the central optical fiber 6 and the oil-filled casing 1, reduces microbending losses, and provides a secondary waterproofing function, ensuring long-term stable transmission of the central optical fiber 6. The FRP reinforcement 2 is resistant to seawater corrosion and has strong resistance to lateral pressure and tensile strength. It is tightly combined with the oil-filled casing 1 through spiral twisting, providing solid mechanical support for the optical cable and avoiding the insufficient compressive and tensile strength caused by the loose fit between the reinforcement 2 and the casing in existing structures. The inner and outer sheaths 5 of HDPE material are salt water resistant, UV resistant, and have high mechanical strength, can provide a uniform protective layer, and simplify the manufacturing process, avoiding the problems of loose structure and uneven surface caused by existing multi-layer wrapping and multiple extrusions.

[0024] See Figure 2 The embodiment of the present invention further provides a method for manufacturing a shape-sensing optical cable, comprising the following steps: Step S10: heating and melting the polybutylene terephthalate raw material on an extruder, and extruding it through a tube drawing die to form an oil-filled casing 1. At the same time, the central optical fiber 6 is inserted into the oil-filled casing 1, and the grease 7 is injected and then cooled to set the shape; Step S20: Melting nylon material on the optical fiber in an extruder and tightly wrapping it through a tube drawing die, followed by vacuum sizing to obtain a tight-cup optical fiber 4; Step S30: placing a plurality of fiber-reinforced plastic reinforcements 2 on the turntable of a cabling machine and spirally stranding them on the prepared oil-filled casing 1. Subsequently, a high-density polyethylene inner sheath 3 with spiral grooves 8 is extruded through a special extrusion die. The prepared tight-buffered optical fibers 4 are then embedded in the corresponding spiral grooves 8 to form a cable core. Step S40: Extruding an outer sheath 5 of high-density polyethylene material from the cable core on an extruder to obtain the final shape-sensing optical cable.

[0025] Furthermore, the outer diameter of the oil-filled casing 1 is 2±0.1mm, the sum of the diameter of the reinforcement member 2 and the thickness of the inner sheath 3 is 7±0.3mm, the thickness of the outer sheath 5 is 2±0.2mm, and the total outer diameter of the optical cable is 11±0.6mm. The outer diameter of the tight-buffered optical fiber 4 is 0.9±0.05mm, and the inner diameter of the spiral tube groove 8 is 1.3±0.05mm. Specifically, in this embodiment, the outer diameter of the oil-filled casing 1 is 2mm, the sum of the diameter of the reinforcement member 2 and the thickness of the inner sheath 3 is 7mm, the thickness of the outer sheath 5 is 2mm, and the total outer diameter of the optical cable is 11mm. The outer diameter of the tight-buffered optical fiber 4 is 0.9mm, and the inner diameter of the spiral tube groove 8 is 1.3mm. In the above process steps, the extrusion temperature of the tight-buffered optical fiber 4 and the inner and outer sheaths 5 is 230°C-255°C.

[0026] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0027] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A shape-sensing optical cable, characterized in that: include: An oil-filled casing, wherein a central optical fiber is disposed in the oil-filled casing, and grease is disposed between the oil-filled casing and the central optical fiber; a plurality of reinforcement members spirally twisted on the oil-filled casing; An inner sheath is arranged outside the reinforcement member, and a plurality of spiral tube grooves are spaced apart along the circumference of the inner sheath; A plurality of tight-buffered optical fibers correspond one-to-one to a plurality of the spiral tube grooves, and the tight-buffered optical fibers are embedded in the corresponding spiral tube grooves; The outer sheath is directly arranged outside the inner sheath.

2. The shape-sensing optical cable according to claim 1, characterized in that: The central optical fiber and the tight-buffered optical fiber are grating optical fibers and / or polarization optical fibers.

3. The shape-sensing optical cable according to claim 1, wherein: The overall density of the optical cable is 0.95-1.05 g / cm 3 between.

4. The shape-sensing optical cable according to claim 1, wherein: The oil-filled sleeve is made of polybutylene terephthalate material.

5. The shape-sensing optical cable according to claim 1, wherein: The reinforcement is made of fiber reinforced plastic material.

6. The shape-sensing optical cable according to claim 1, characterized in that: The inner sheath and the outer sheath are both made of high-density polyethylene material.

7. A method for manufacturing a shape sensing optical cable according to any one of claims 1 to 6, characterized in that: The steps include: The polybutylene terephthalate raw material is heated and melted on the extruder, and then extruded through a tube drawing die to form an oil-filled sleeve. At the same time, the central optical fiber is inserted into the oil-filled sleeve, and the oil is injected and then cooled to shape. The optical fiber is melted with nylon material on an extruder and tightly wrapped through a tube drawing die, and then sized by vacuum to obtain a tight-cup optical fiber; Several fiber-reinforced plastic reinforcements are placed on the turntable of the cabling machine and spirally twisted on the prepared oil-filled casing. Subsequently, a high-density polyethylene inner sheath with spiral grooves is extruded through a special extrusion die. The prepared tight-buffered optical fibers are then embedded in the corresponding spiral grooves to form a cable core. The cable core is extruded with an outer sheath of high-density polyethylene material on an extruder to obtain the final shape-sensing optical cable.

8. The method for manufacturing a shape-sensing optical cable according to claim 7, wherein: The outer diameter of the oil-filled casing is 2±0.1 mm, the sum of the diameter of the reinforcement and the thickness of the inner sheath is 7±0.3 mm, the thickness of the outer sheath is 2±0.2 mm, and the total outer diameter of the optical cable is 11±0.6 mm.

9. The method for manufacturing a shape-sensing optical cable according to claim 7, wherein: The outer diameter of the tight-cup optical fiber is 0.9±0.05 mm, and the inner diameter of the spiral tube groove is 1.3±0.05 mm.

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