Multi-stage protection device and method for fiber core connection section of optical fiber cable

Abstract

The invention discloses a multi-stage protection device for a fiber core connection section of an optical fiber cable. The multi-stage protection device comprises a shell, a waterproof outgoing line connector and an optical fiber connector sealing pipe. The interior of the shell is hollow, and through holes are formed in one set of opposite side faces respectively. The waterproof outgoing line connector is fixedly installed at the through hole, and the to-be-connected ends of the group of optical fibers and cables enter the housing through the waterproof outgoing line connector. The optical fiber connector sealing tube is fixedly arranged in the shell, and the fiber core connectors of the group of optical fiber cables are packaged in the optical fiber connector sealing tube. The optical fiber connector sealing pipe, the inner box body, the box body and the like form triple protection on the optical fiber connector, so that internal fusion welding optical fibers can be better protected and are prevented from being influenced by external factors, the loss of optical fiber transmission is reduced, and the reliability of optical fiber transmission information is improved. Through the multi-protection arrangement, the device can bear the pressure of seawater of more than 500m, and can be used for a long time in five-high environments of high salt mist, high humidity, high temperature, high illumination and high radiation of islands and reefs.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber splicing protection, and in particular to a multi-stage protection device and method for a fiber core splicing section of an optical fiber cable. Background Art

[0002] Fiber optic sensors have the advantages of anti-electromagnetic interference, anti-corrosion, electrical insulation, high sensitivity and low cost, and have good compatibility with ordinary optical fibers. They are widely used in the field of geotechnical engineering sensing.

[0003] Since the resonant wavelength or frequency of the optical fiber sensor is sensitive to the stress, strain and temperature of the rock and soil, it is mainly used to measure temperature, stress and strain. The field of geotechnical engineering, including tunnel engineering, pipeline engineering, island and reef monitoring engineering, bridge engineering, mining engineering, etc., has begun to use optical fiber sensors for safety monitoring.

[0004] In terms of long-distance monitoring of rock mass engineering, fiber optic sensing technology has been fully developed and widely used. However, the fusion splicing between optical fibers is a key link, and the reliability of the fusion splice will affect the stability and reliability of the monitoring system. The splice protection device of the optical fiber fusion splice can protect the end face of the optical fiber after fusion from damage by the external environment and ensure the stable transmission of the optical signal. Due to problems in material selection, packaging process and protection methods in the optical fiber cable splice protection device, under complex working conditions and long-term operation, the fusion splice is easily flooded or damaged, resulting in excessive light loss or even disconnection of the optical fiber fusion splice, which in turn leads to data loss and the inability to collect sensor data. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a multi-level protection device and method for the fiber core splicing section of an optical fiber cable, and specifically includes the following technical solutions: A multi-stage protective device for the core splicing section of an optical fiber cable comprises a shell, a waterproof outlet connector, and an optical fiber connector sealing tube; the shell is hollow inside and is respectively provided with through holes at a set of opposite side surfaces thereof; the waterproof outlet connector is fixedly installed at the through holes, and the ends to be spliced ​​of a group of optical fiber cables respectively enter the shell through the waterproof outlet connector; the optical fiber connector sealing tube is fixedly arranged inside the shell, and the core connectors of the group of optical fiber cables are encapsulated inside the optical fiber connector sealing tube.

[0006] Furthermore, the shell includes a box body and a cover plate, and the cover plate is fixedly fitted to cover the open end face of the box body; an inner box body is also arranged inside the box body, and the inner box body has an optical fiber core through hole on its side; the optical fiber joint sealing tube is arranged inside the inner box body, and the core of the group of optical fiber cables passes through the optical fiber core through hole, and the core joint is encapsulated inside the optical fiber joint sealing tube.

[0007] Furthermore, the open end face of the box body is provided with a circle of continuous grooves, a sealing ring is embedded at the bottom of the groove, and the cover plate is provided with a circle of continuous protrusions matching the groove; the upper end face of the inner box body is flush with the upper end face of the box body, and a circle of sealing strips is fixedly provided on the upper end face of the inner box body, and the sealing strips are higher than the upper end face of the box body; after the box body and the cover plate are buckled and fixed, the protrusions abut the sealing ring, so that the shell forms a closed space; the sealing strip abuts the inner side face of the cover plate, so that the inner box body forms a closed space.

[0008] Furthermore, a clamp, a limiting column and a retaining spring are provided inside the box body; the clamp is fixedly arranged on the bottom surface of the box body for firmly pressing the optical fiber cable; a plurality of limiting columns are provided, which are arranged at intervals on the bottom surface of the box body and are arranged outside the inner box body for combing and guiding the optical fiber core; the retaining spring is arranged inside the inner box body for fixing the optical fiber joint sealing tube.

[0009] Furthermore, a protective coating is provided on the outer side of the shell, and the protective coating is a UV coating or a fluorocarbon coating.

[0010] Furthermore, the waterproof outlet connector is in the shape of a hollow cylinder as a whole, and the outer side surface is divided into an insertion section and a locking section; the insertion section is threadedly connected to the through hole on the inner side surface of the shell body to secure the waterproof outlet connector to the side surface of the box body; the protective device also includes a locking portion, which is installed on the locking section and is used to fasten the optical fiber cable; the locking portion includes a rubber column, a clamping mechanism, and a fastening nut; the rubber column is installed inside the waterproof outlet connector and forms an installation cavity with the waterproof outlet connector, and the optical fiber cable passes through the rubber column; the fastening nut has a through hole for the optical fiber cable to pass through; the clamping mechanism is embedded in the installation cavity, and under the locking action of the fastening nut, the clamping mechanism applies force to the rubber column to make the rubber column fit tightly to the optical fiber cable.

[0011] Furthermore, the clamping mechanism includes a cylindrical body; an annular tightening ring is provided on the outer side surface of one end of the cylindrical body, and the other end is embedded in the installation cavity formed by the rubber column and the locking section; the annular tightening ring includes a plurality of elastic sheets arranged around one end surface of the cylindrical body; one end of the elastic sheet is fixedly connected to the cylindrical body, and the other end is a free end; the free end of the elastic sheet can be deformed and gathered inward under the action of external force.

[0012] Furthermore, after the cylindrical body is embedded in the installation cavity, the elastic sheet is embedded in the installation cavity with a length of ≧1 / 2; the fastening nut and the locking section are fixed by threaded locking, and the inner diameter of the fastening nut is smaller than the outer diameter of the annular tightening ring.

[0013] Furthermore, the outer diameter of the rubber column is smaller than the inner diameter of the waterproof outlet connector; a circle of convex ridges is provided at the bottom end of the rubber column, and the size of the convex ridges is larger than the inner diameter of the waterproof outlet connector.

[0014] Furthermore, the optical fiber joint sealing tube includes a tube body and a tube plug; the tube body is a hollow vacuum sandwich tube; the tube plug is fixedly installed at both ends of the tube body and is provided with a through hole for the optical fiber core to penetrate.

[0015] Furthermore, the optical fiber joint sealing tube also includes a buffer layer, and the buffer layer is arranged inside the tube body.

[0016] Furthermore, the inner tube and the outer tube are integrally formed; a plurality of O-rings are arranged at intervals on the outer side surface of the tube plug; and the buffer layer is small silica gel balls or gel.

[0017] Furthermore, after the optical fiber core is connected, its outside is wrapped with a reinforced heat shrink tube; the reinforced heat shrink tube is arranged inside the tube body.

[0018] Furthermore, the tube body of the optical fiber joint sealing tube and the shell are made of one material selected from stainless steel, aluminum alloy or titanium alloy.

[0019] Using the above protection device, the present invention also records a multi-level protection method for the fiber core splicing section of an optical fiber cable, comprising the following steps: S1, optical fiber cable A and optical fiber cable B to be connected pass through waterproof outlet connectors into the box body and are fixed with clamps; S2, stripping the ends to be connected of the optical fiber cable A and the optical fiber cable B, separating the multiple optical fiber cores inside, and guiding the ends to be connected of the optical fiber cores into the interior of the inner box body by means of limiting pillars; S3, take the optical fiber joint sealing tube, install a tube plug at one end of the tube, pass the core of the optical fiber cable A through the tube plug, and make the core extend from the other end of the optical fiber joint sealing tube, and use a reinforced heat shrink tube to cover the optical fiber cable A; S4, passing the core of optical fiber cable B through another pipe plug, and completing the fusion connection with optical fiber cable A outside the optical fiber joint sealing tube; S5, completely covering the optical fiber connector with the reinforced heat shrink tube, heating the heat shrink tube to complete the coating operation, so that the heat shrink tube fits tightly to the optical fiber connector; S6, injecting silica gel balls or gel into the optical fiber connector sealing tube, and then fixing the tube plugs at both ends of the optical fiber connector sealing tube; S7, fix the optical fiber connector sealing tube to the inside of the inner box body through the retaining ring, buckle the cover plate on the opening end of the box body, use screws to complete the fastening and fixation, and complete the fastening and fixation of the waterproof outlet connector to the optical fiber cable.

[0020] Based on the above technical solution, the present invention has the following beneficial effects: 1. The optical fiber joint is triple-protected by the optical fiber joint sealing tube, inner box body and box body, which can better protect the fused optical fiber inside the device from the influence of external factors, reduce the loss of optical fiber transmission, and increase the reliability of optical fiber transmission information. And through this multiple protection setting, the device can withstand the pressure of seawater above 500m, and the device can be used for a long time in the five high environments of high salt fog, high humidity, high temperature, high light and high radiation on islands and reefs.

[0021] 2. The box body, inner box body and fiber optic connector sealing tube are all made of stainless steel, aluminum alloy, titanium alloy and other materials. The use of such materials can make the protective device have the functions of corrosion resistance, pressure resistance, high temperature resistance and radiation resistance. The integrated molding can avoid the gaps and notches that may appear at the joints, thereby significantly improving the protective performance of the protective device.

[0022] 3. The optical fiber joint sealing tube can not only prevent the internal fusion-spliced ​​optical fiber from being damaged, but also prevent the fusion-spliced ​​optical fiber from bending and deforming, thereby reducing optical fiber loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Schematic diagram of the device structure in an exemplary embodiment (1); Figure 2 : Schematic diagram of the device structure in the exemplary embodiment (2); Figure 3 : Schematic diagram of the waterproof outlet connector structure in an exemplary embodiment; Figure 4 : Schematic diagram of the optical fiber connector sealing tube structure in an exemplary embodiment.

[0024] Explanation of symbols 1-shell, 101-box body, 102-cover plate, 103-clamp, 104-limiting column, 105-inner box body; 2-waterproof outlet connector, 201-insertion section, 202-limiting nut, 203-locking section; 301-rubber column, 302-convex ridge, 303-cylindrical body, 304-annular tightening ring, 305-elastic sheet, 306-fastening nut; 4-fiber optic connector sealing tube, 401-tube body, 402-tube plug, 403-buffer layer, 404-reinforced heat shrink tube, 405-O-ring, 406-conical sealing ring; 5-circlip; 6-fiber cable, 601-fiber core. DETAILED DESCRIPTION

[0025] It should be noted that: 1. Certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. This specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction.

[0026] 2. Unless otherwise clearly specified and limited, the terms "installation", "setting", "connection", etc. should be understood in a broad sense. For example, "connection" 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 an indirect connection through an intermediate medium, or it can be the internal connection of 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.

[0027] 3. Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the common meanings understood by persons with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components.

[0028] The following is combined with Figure 1 -Attached Figure 4 , the present invention is described in detail by way of embodiments.

[0029] This embodiment describes a multi-stage protective device for a fiber core splicing section of an optical fiber cable, comprising a housing 1 , a waterproof outlet connector 2 , and an optical fiber connector sealing tube 4 .

[0030] The housing 1 comprises a box body 101 and a cover plate 102 . The cover plate 102 is fitted and covers the open end surface of the box body 101 and is fixed at four corners with screws.

[0031] The housing 1 is made of stainless steel, aluminum alloy, titanium alloy and other materials with corrosion resistance, pressure resistance, high temperature resistance and radiation resistance. The outer side of the housing 1 is also provided with a protective coating, such as a UV coating, a carbon fluorine coating, etc. The housing 1 provides the first level of protection for the optical fiber inside, so that the optical fiber splicing section can work normally in the island and reef environment with high temperature, high humidity, high light, high salt fog and high radiation.

[0032] The opening end surface of the box body 101 is provided with a circle of continuous grooves, and a sealing ring is embedded in the groove; the cover plate 102 is provided with a circle of protrusions that match the grooves. After the cover plate 102 and the box body 101 are buckled and fixed, the protrusions contact the sealing ring to form a sealing structure, which can effectively prevent moisture, salt, etc. from penetrating into the box body 101.

[0033] The box body 101 is provided with threaded mounting holes at a set of opposite sides thereof for mounting the waterproof outlet connector 2. The two sections of optical fiber cables 6 to be spliced ​​have their ends to be spliced ​​enter the box body 101 through the waterproof outlet connector 2, and the fiber core splicing operation is completed inside the box body 101. Here, the two sections of optical fiber cables 6 to be spliced ​​can be defined as a set of optical fiber cables 6.

[0034] The waterproof outlet connector 2 is in the shape of a hollow cylinder as a whole, and the outer side is divided into an insertion section 201 and a locking section 203 by a limiting nut 202 .

[0035] The insertion section 201 is provided with an external thread, and by cooperating with the thread of the threaded mounting hole, the waterproof outlet connector 2 can be firmly installed on the side of the box body 101. A sealing ring is provided at the threaded mounting hole to prevent moisture, salt, etc. from penetrating into the box body 101.

[0036] The locking section 203 is used to install the locking part, which includes a rubber column 301 , a clamping mechanism, and a fastening nut 306 .

[0037] The outer diameter of the rubber column 301 is smaller than the inner diameter of the waterproof outlet connector 2 . The bottom of the rubber column 301 is integrally formed with a circle of convex ribs 302 , and the size of the convex ribs 302 is larger than the inner diameter of the waterproof outlet connector 2 .

[0038] After the rubber column 301 is installed inside the waterproof outlet connector 2, the convex rib 302 is interference fit inside the waterproof outlet connector 2 to prevent moisture from penetrating into the box body 101. An installation cavity is formed between the column body of the rubber column 301 and the locking section, and the end face of the rubber column 301 is set flush with the end face of the locking section 203.

[0039] The clamping mechanism comprises a cylindrical body 303 , an annular tightening ring 304 is arranged on the outer side surface of one end of the cylindrical body 303 , and the other end is embedded in the installation cavity formed by the rubber column 301 and the locking section 203 .

[0040] The annular tightening ring 304 is composed of a plurality of elastic sheets 305 arranged around the end surface of the cylindrical body 303. One end of the elastic sheet 305 is fixedly connected to the cylindrical body 303, and the other end is a free end. The free end of the elastic sheet 305 can be deformed and gathered inward under the action of an external force. The length of the cylindrical body 303 is set so that after the cylindrical body 303 is embedded in the installation cavity, at least 1 / 2 of the length of the elastic sheet 305 is embedded in the installation cavity.

[0041] The fastening nut 306 is provided with a through hole for passing the optical fiber cable 6 . The fastening nut 306 and the locking section 203 are fixed by thread locking, and the inner diameter of the fastening nut 306 is smaller than the outer diameter of the annular tightening ring 304 .

[0042] When the fastening nut 306 is rotated to thread-fasten with the locking section 203 , the elastic sheet 305 is forced to shrink and lock the rubber column 301 inside the fastening nut 306 , so that the rubber column 301 fits tightly with the optical fiber cable 6 to prevent moisture from penetrating into the box body 101 .

[0043] After the end of the optical fiber cable 6 to be connected passes through the threaded mounting hole on the side of the box body 101 and enters the interior of the box body 101, an optical cable fixing part is provided inside the box body 101 to keep the optical fiber cable 6 in a stable position, avoid poor contact of the joint due to shaking, and reduce optical fiber loss.

[0044] The optical cable fixing portion includes a clamp 103 and a limiting column 104 .

[0045] The clamp 103 is arranged on the bottom surface of the box body 101, and is further arranged at the threaded mounting hole near the side of the box body 101, for firmly pressing the optical fiber cable 6 to ensure that the optical fiber cable 6 is firmly fixed. The clamp 103 is fixedly connected to the bottom surface of the box body 101, and the connection method includes but is not limited to welding, threaded fixing, etc.

[0046] The limiting posts 104 are provided in plurality, distributed at intervals on the bottom surface of the box body 101, and preferably arranged in a straight line, and further arranged to be arranged parallel to the side surface of the box body. The side surface of the box body refers to the side surface of the box body provided with the threaded mounting holes.

[0047] The limiting post 104 is preferably configured to be integrally formed with the box body 101 , and is used to comb and guide the optical fiber to prevent the optical fiber from becoming tangled and entangled inside the box body 101 .

[0048] A circle of baffles is integrally formed on the inner bottom surface of the box body 101 , and the baffles constitute the inner box body 105 . The inner box body 105 is arranged between two opposite groups of limiting pillars 104 .

[0049] The upper end surface of the inner box body 105 is flush with the upper end surface of the box body 101, and a circle of sealing strip is fixedly provided on the upper end surface of the inner box body 105, and the sealing strip is higher than the upper end surface of the box body 101. After the box body 101 and the cover plate 102 are buckled and fixed, the sealing strip contacts the inner side surface of the cover plate 102, so that the inner box body 105 forms a closed space.

[0050] The inner box body 105 is provided with an optical fiber core through hole on the side thereof, for guiding the end to be connected of the optical fiber core 601 to enter the interior of the inner box body 105 .

[0051] The inner box body 105 is also made of stainless steel, aluminum alloy, titanium alloy and other materials with corrosion resistance, pressure resistance, high temperature resistance and radiation resistance, providing a second level of protection for the optical fiber inside.

[0052] The optical fiber joint sealing tube 4 is arranged inside the inner box body 105 and fixed by a clamping spring 5. The clamping spring 5 can provide elastic buffering, and when vibration occurs, the clamping spring 5 can maintain the stable state of the optical fiber joint sealing tube 4.

[0053] The optical fiber joint sealing tube 4 includes a tube body 401 , a tube plug 402 , a buffer layer 403 , and a reinforced heat shrink tube 404 .

[0054] The tube body 401 is a hollow tube, including an inner tube and an outer tube, and a vacuum interlayer is formed between the inner tube and the outer tube, that is, the tube body 401 is a hollow vacuum interlayer tube.

[0055] It is preferred that the inner tube and the outer tube are integrally formed to further enhance the compressive strength of the tube body 401 and obtain a better vacuum insulation effect.

[0056] The pipe plugs 402 are installed at both ends of the pipe body 401 to block the opening of the pipe body 401 .

[0057] The tube plug 402 is preferably made of silicone material. The tube plug 402 is provided with a through hole for the optical fiber core 601 to penetrate. The outer diameter of the tube plug 402 is set larger than the inner diameter of the tube body 401 to obtain an interference fit sealing effect.

[0058] Furthermore, a plurality of O-rings 405 are disposed at intervals on the outer side of the pipe plug 402 to obtain a better sealing effect.

[0059] This embodiment does not limit the connection method between the pipe plug and the pipe body, and installation methods such as embedding and threading can be used.

[0060] A buffer layer 403 is provided inside the tube body 401 , and the buffer layer 403 is preferably filled with silica gel balls or gel to obtain a better elastic buffering effect.

[0061] Furthermore, in order to have both buffering and heat preservation effects, the buffer layer 403 is filled with polyurethane foaming agent, which has excellent heat preservation performance, can effectively prevent heat conduction, and provide a good heat preservation effect.

[0062] After the optical fiber is connected, the outside is wrapped with a reinforced heat shrink tube 404, which is arranged inside the tube body 401 and immersed in the buffer layer 403. The reinforced heat shrink tube 404 can tightly fit and wrap the joint of the optical fiber core 601 to maintain good contact of the joint.

[0063] The tube body 401 of the optical fiber joint sealing tube 4 is also made of stainless steel, aluminum alloy, titanium alloy and other materials with corrosion resistance, pressure resistance, high temperature resistance and radiation resistance, providing the third level of protection for the optical fiber inside.

[0064] In this embodiment, 1. The clamping mechanism and the fastening nut 306 of the locking part can be made of nylon 66, which has high strength and is also anti-corrosive and waterproof.

[0065] 2. The sealing parts recorded, such as sealing rings, convex strips, sealing strips, etc., can be made of rubber material so that the waterproof pressure of the device is ≧10MPa.

[0066] 3. In order to obtain excellent sealing and plugging effect, the pipe plug 402 is connected to the pipe body by threads to ensure the firmness of the connection; the O-ring is set in a compression type; the inside of the pipe plug 402 adopts a conical design, and a conical sealing ring 406 is placed to seal the optical fiber and the pipe plug to further protect the optical fiber.

[0067] Through the above-mentioned multiple protection settings, the device can withstand the pressure of seawater above 500m and endure the five high environments of high salt fog, high humidity, high temperature, high light and high radiation of islands and reefs.

[0068] Based on the above-mentioned splicing device, this embodiment also records a multi-level protection method for splicing the core of an optical fiber cable, including the following steps: S1, optical fiber cable A and optical fiber cable B to be connected pass through waterproof outlet connectors into the box body and are fixed with clamps; S2, stripping the end to be connected of the optical fiber cable A / B, separating the multiple optical fiber cores inside, and guiding the end to be connected of the optical fiber core into the interior of the inner box body by using the limiting column; S3, take the optical fiber joint sealing tube, install a tube plug at one end of the tube, pass the core of the optical fiber cable A through the tube plug, and make the core extend from the other end of the optical fiber joint sealing tube, and use a reinforced heat shrink tube to cover the optical fiber cable A; S4, passing the core of optical fiber cable B through another pipe plug, and completing the fusion connection with optical fiber cable A outside the optical fiber joint sealing tube; S5, completely covering the optical fiber connector with the reinforced heat shrink tube and partially covering the optical fiber core, heating to complete the coating operation of the heat shrink tube, so that the heat shrink tube fits tightly to the optical fiber connector; S6, injecting silica gel balls or gel into the optical fiber connector sealing tube, and then fixing the tube plugs at both ends of the optical fiber connector sealing tube; S7, fix the optical fiber connector sealing tube to the inside of the inner box body through the retaining ring, buckle the cover plate on the opening end of the box body, use screws to complete the fastening and fixation, and complete the fastening and fixation of the waterproof outlet connector to the optical fiber cable.

[0069] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A multi-stage protection device for the core splicing section of an optical fiber cable, characterized in that: It includes a housing, a waterproof outlet connector, and an optical fiber connector sealing tube; The shell is hollow inside and is provided with through holes at a set of opposite sides thereof; The waterproof outlet connector is fixedly installed at the through hole, and the ends to be connected of a group of optical fiber cables respectively enter the interior of the housing through the waterproof outlet connector; The optical fiber joint sealing tube is fixedly arranged inside the housing, and the core joints of the group of optical fiber cables are encapsulated inside the optical fiber joint sealing tube.

2. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 1, characterized in that: The housing comprises a box body and a cover plate, wherein the cover plate is fixedly fitted and covers the open end surface of the box body; An inner box body is arranged inside the box body, and an optical fiber core through hole is arranged on a side of the inner box body; The optical fiber joint sealing tube is arranged inside the inner box body, the cores of the group of optical fiber cables pass through the optical fiber core through holes, and the core joints are encapsulated inside the optical fiber joint sealing tube.

3. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 2, characterized in that: The opening end surface of the box body is provided with a circle of continuous grooves, a sealing ring is embedded in the groove, and the cover plate is provided with a circle of continuous protrusions matching with the grooves; The upper end surface of the inner box body is flush with the upper end surface of the box body, and a circle of sealing strip is fixedly arranged on the upper end surface of the inner box body, and the sealing strip is higher than the upper end surface of the box body; After the box body and the cover plate are buckled and fixed, the protrusion contacts the sealing ring, so that the shell forms a closed space; the sealing strip contacts the inner side of the cover plate, so that the inner box body forms a closed space.

4. A multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 2 or 3, characterized in that: A clamp, a limiting column and a retaining spring are arranged inside the box body; the clamp is fixedly arranged on the bottom surface of the box body for firmly pressing the optical fiber cable; a plurality of limiting columns are arranged at intervals on the bottom surface of the box body and outside the inner box body for combing and guiding the optical fiber core; the retaining spring is arranged inside the inner box body for fixing the optical fiber joint sealing tube.

5. A multi-stage protection device for the fiber core splicing section of an optical fiber cable according to any one of claims 1 to 4, characterized in that: The outer side of the shell is provided with a protective coating, and the protective coating is a UV coating or a fluorocarbon coating.

6. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 1, characterized in that: The waterproof outlet connector is in the shape of a hollow cylinder, and the outer side is divided into an insertion section and a locking section; the insertion section is threadedly connected to the through hole on the inner side of the shell, so as to secure the waterproof outlet connector on the side of the box body; the protective device also includes a locking portion, which is mounted on the locking section and is used to fasten the optical fiber cable; The locking part includes a rubber column, a clamping mechanism, and a fastening nut; the rubber column is installed inside the waterproof outlet connector and forms an installation cavity with the waterproof outlet connector, and the optical fiber cable passes through the rubber column; the fastening nut has a through hole for the optical fiber cable to pass through; the clamping mechanism is embedded in the installation cavity, and under the locking action of the fastening nut, the clamping mechanism applies force to the rubber column to make the rubber column fit tightly against the optical fiber cable.

7. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 6, characterized in that: The clamping mechanism comprises a cylindrical body; an annular tightening ring is arranged on the outer side surface of one end of the cylindrical body, and the other end is embedded in the installation cavity formed by the rubber column and the locking section; The annular tightening ring includes a plurality of elastic sheets arranged around one end surface of a cylindrical body; one end of the elastic sheet is fixedly connected to the cylindrical body, and the other end is a free end; the free end of the elastic sheet can be deformed and gathered inward under the action of an external force.

8. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 7, characterized in that: After the cylindrical body is embedded in the installation cavity, the elastic sheet is embedded in the installation cavity with a length of ≧1 / 2; The fastening nut and the locking section are fixed by thread locking, and the inner diameter of the fastening nut is smaller than the outer diameter of the annular tightening ring; The outer diameter of the rubber column is smaller than the inner diameter of the waterproof outlet connector; A circle of convex ridges is arranged at the bottom end of the rubber column, and the size of the convex ridges is larger than the inner diameter of the waterproof outlet connector.

9. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 1, characterized in that: The optical fiber joint sealing tube comprises a tube body and a tube plug; The tube body is a hollow vacuum sandwich tube; The pipe plug is fixedly mounted on both ends of the pipe body and is provided with a through hole for the optical fiber core to penetrate.

10. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 9, characterized in that: The optical fiber joint sealing tube also includes a buffer layer, which is arranged inside the tube body and is at least one of silica gel balls, gel or polyurethane foaming agent.

11. The multi-stage protection device for the fiber core splicing section of an optical fiber cable according to claim 10, characterized in that: The outer side of the pipe plug is provided with a plurality of O-rings at intervals in a compression manner. The pipe plug is connected to the pipe body by a thread. The inside of the pipe plug is provided with a conical shape and a conical sealing ring is placed therein. The tube body of the optical fiber joint sealing tube and the shell are made of stainless steel, aluminum alloy or titanium alloy in an integrated manner; After the optical fiber core is connected, the outside is wrapped with a reinforced heat shrink tube; the reinforced heat shrink tube is arranged inside the tube body.

12. A multi-level protection method for the fiber core splicing section of an optical fiber cable, characterized in that: The following steps are involved: S1, optical fiber cable A and optical fiber cable B to be connected pass through waterproof outlet connectors into the box body and are fixed with clamps; S2, stripping the ends to be connected of the optical fiber cable A and the optical fiber cable B, separating the multiple optical fiber cores inside, and guiding the ends to be connected of the optical fiber cores into the interior of the inner box body by means of limiting pillars; S3, take the optical fiber joint sealing tube, install a tube plug at one end of the tube, pass the core of the optical fiber cable A through the tube plug, and make the core extend from the other end of the optical fiber joint sealing tube, and use a reinforced heat shrink tube to cover the optical fiber cable A; S4, passing the core of optical fiber cable B through another pipe plug, and completing the fusion connection with optical fiber cable A outside the optical fiber joint sealing tube; S5, completely covering the optical fiber connector with the reinforced heat shrink tube, heating the heat shrink tube to complete the coating operation, so that the heat shrink tube fits tightly to the optical fiber connector; S6, injecting silica gel balls or gel into the optical fiber connector sealing tube, and then fixing the tube plugs at both ends of the optical fiber connector sealing tube; S7, fix the optical fiber connector sealing tube to the inside of the inner box body through the retaining ring, buckle the cover plate on the opening end of the box body, use screws to complete the fastening and fixation, and complete the fastening and fixation of the waterproof outlet connector to the optical fiber cable.

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