Spot welding type strain sensor of rubber-covered wire fiber bragg grating and manufacturing method thereof

Abstract

The invention belongs to the technical field of fiber bragg grating sensors, and particularly relates to a rubber-covered wire fiber bragg grating spot welding type strain sensor and a manufacturing method thereof.The sensor comprises a fiber core, the outer side of the fiber core is wrapped with a protective sleeve, the fiber core comprises a fiber section and a grating section, the grating section extends out of one end of the protective sleeve, and the fiber section extends out of the other end of the protective sleeve; one end of the metal tube is fixed with one end of the protective sleeve, the fiber core penetrates through the center of the metal tube, and the metal tube is fixed with the fiber core; the metal tube is filled with a filler protection part for protecting the fiber core, and the filler protection part fixes the metal tube and the fiber core; the metal substrate is fixedly connected to the other end of the metal tube, the metal substrate is used for being fixed to the steel wire, and the grating section is fixed to the metal substrate. The invention further discloses a manufacturing method of the sensor. Compared with the prior art, a steel wire-metal substrate-grating transmission path is innovatively adopted, the strain transmission efficiency is improved, and the sensor has the advantages of being good in installation stability, high in durability and long in service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber Bragg grating sensors, and particularly relates to a drop-welded strain sensor for drop-welded fiber optic cable with fiber Bragg grating and a manufacturing method thereof. Background Art

[0002] The basic principle of a fiber Bragg grating sensor is to use ultraviolet light to expose the side of an optical fiber or other writing methods to make the refractive index within a small section of the fiber core change periodically along the optical fiber axis to obtain a fiber Bragg grating; the fiber Bragg grating can partially or completely reflect a specific wavelength of light in the incident light. By detecting the Bragg wavelength spectrum reflected by the grating, the absolute measurement of the strain and temperature values of the measured structure can be realized. The resonant wavelength of the fiber Bragg grating is sensitive to changes in the external environment, so it has been increasingly widely used in structural health monitoring.

[0003] Although the research on fiber Bragg grating strain sensors has been continuously deepening in recent years, at present, fiber Bragg grating strain sensors still have the following problems:

[0004] (1) Low strain transfer efficiency. The strain transfer path of traditional fiber Bragg grating sensors needs to pass through multiple interface losses, such as "steel wire - metal substrate - metal tube - grating", resulting in low strain transfer efficiency and lag errors in measurement results.

[0005] (2) Insufficient installation stability and long-term reliability. Traditional fiber Bragg grating sensors mostly rely on adhesives (such as epoxy resin) or embedded encapsulation for installation. The adhesive method is easily affected by factors such as environmental temperature and humidity, ultraviolet aging, etc., resulting in creep, embrittlement or even shedding of the adhesive layer, and significant drift in long-term monitoring data; although the embedded encapsulation can improve stability, the strain transfer efficiency between the sensor and the substrate is affected by the stiffness of the encapsulation material, and it is difficult to accurately reflect the actual strain state.

[0006] (3) Insufficient encapsulation protection and durability. In harsh environments (such as marine corrosion, chemical pollution), traditional encapsulation materials (such as armored) are prone to fiber breakage, resulting in fiber microbending loss or degradation of grating performance.

[0007] Therefore, we urgently need a drop-welded strain sensor for drop-welded fiber optic cable with fiber Bragg grating and a manufacturing method thereof to solve the above deficiencies. Summary of the Invention

[0008] The purpose of the present invention is to provide a drop-welded strain sensor for drop-welded fiber optic cable with fiber Bragg grating and a manufacturing method thereof. The drop-welded fiber optic cable has a long transmission distance, low signal attenuation, strong anti-interference ability, is suitable for long-distance communication requirements, has good flexibility, strong compressive performance, and convenient construction to solve the above problems.

[0009] To achieve the above purpose, the present invention provides the following solutions:

[0010] Pigtail fiber grating spot welding type strain sensor, comprising:

[0011] A fiber core, with a protective sleeve wrapped around the outside of the fiber core. The fiber core includes an optical fiber section and a grating section. One end of the grating section extends out of the protective sleeve, and the other end of the optical fiber section extends out of the protective sleeve;

[0012] A metal tube, with one end fixed to one end of the protective sleeve. The fiber core passes through the center of the metal tube, and the metal tube is fixed to the fiber core;

[0013] A filler protection part for protecting the fiber core is filled in the metal tube. The filler protection part fixes the metal tube to the fiber core;

[0014] A metal substrate is fixedly connected to the other end of the metal tube. The metal substrate is used to fix to a steel wire, and the grating section is fixed on the metal substrate.

[0015] Optionally, the protective sleeve is a pigtail. The pigtail is wrapped around the outside of the fiber core. One end of the grating section extends out of the pigtail, and the other end of the optical fiber section extends out of the pigtail.

[0016] Optionally, the metal tube and the pigtail are fixed by an optical fiber heat shrink tube;

[0017] One end of the optical fiber heat shrink tube is sleeved outside one end of the pigtail, and the other end of the optical fiber heat shrink tube is sleeved outside one end of the metal tube. After the optical fiber heat shrink tube is heated and shrunk, it is fixed to the metal tube and the pigtail respectively.

[0018] Optionally, the filler protection part includes a protective polyurea asphalt glue. The protective polyurea asphalt glue is filled inside the metal tube. The protective polyurea asphalt glue is located between the fiber core and the metal tube. The fiber core is fixed to the metal tube through the protective polyurea asphalt glue.

[0019] Optionally, the grating section is pasted on the metal substrate by a long-term paste glue.

[0020] Optionally, the metal substrate is welded and fixed to the steel wire, and the thickness of the metal substrate is 0.05mm - 0.1mm.

[0021] Optionally, the optical fiber heat shrink tube is made of polyolefin material.

[0022] Optionally, the pigtail is made of polyimide material.

[0023] Optionally, the metal tube is a stainless steel tube;

[0024] The metal substrate is welded and fixed to the metal tube;

[0025] The wall thickness of the metal tube is 0.5 - 1 mm.

[0026] A method for manufacturing a fiber optic grating spot welding type strain sensor for a drop wire, used for manufacturing the above-mentioned fiber optic grating spot welding type strain sensor for a drop wire, includes the following steps:

[0027] Fix the metal tube and the metal substrate.

[0028] Strip both ends of the protective sleeve on the fiber core, so that the grating section at one end of the fiber core and the optical fiber section at the other end of the fiber core are exposed outside both ends of the protective sleeve.

[0029] Pass the grating section through the metal tube and then fix it on the surface of the metal substrate.

[0030] Fill the filler protection part between the metal tube and the fiber core, and fix the metal tube and the fiber core through the filler protection part.

[0031] Fix the metal tube and the protective sleeve.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] During use, fix the metal tube and the metal substrate, strip both ends of the protective sleeve on the fiber core, so that the grating section at one end of the fiber core and the optical fiber section at the other end of the fiber core are exposed outside both ends of the protective sleeve, pass the grating section through the metal tube and then fix it on the surface of the metal substrate, fill the filler protection part between the metal tube and the fiber core, and fix the metal tube and the fiber core through the filler protection part, fix the metal tube and the protective sleeve, to obtain the sensor of the present invention, fix the metal substrate and the steel wire to realize the layout of the sensor of the present invention. Compared with the traditional technology, the present invention innovatively adopts the transmission path of "steel wire - metal substrate - grating", improving the strain transmission efficiency.

[0034] Moreover, the present invention has good installation stability. It connects the sensor and the steel wire in a spot welding manner, and the two are closely attached, and the welding points are evenly distributed, so the installation stability is better, and it has good sensing sensitivity and higher strain measurement accuracy.

[0035] The present invention also has high durability and service life. The drop wire of the present invention is made of polyimide with high temperature resistance, good durability and flexibility, making the fiber optic grating spot welding type strain sensor for a drop wire have better durability, being suitable for the strain monitoring requirements in a variety of complex environments and having a longer service life. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings:

[0037] Figure 1 It is the top view of the structure of the present invention;

[0038] Figure 2 It is the axonometric view of the structure of the present invention;

[0039] Figure 3 It is the schematic structural view of the skin fiber optic grating spot welding type strain sensor of the present invention installed on a steel wire;

[0040] Among them, 1. Fiber core; 1.1. Fiber optic segment; 1.2. Grating segment; 2. Skin wire; 3. Fiber optic heat shrinkable tube; 4. Metal tube; 5. Protective polyurea asphalt glue; 6. Long-term adhesive glue; 7. Metal substrate; 8. Steel wire. Specific embodiments

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0042] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0043] Refer to Figures 1 to 3 , the present invention discloses a skin fiber optic grating spot welding type strain sensor, including:

[0044] Fiber core 1, the outside of the fiber core 1 is wrapped with a protective sleeve. The fiber core 1 includes a fiber optic segment 1.1 and a grating segment 1.2. One end of the grating segment 1.2 extends out of the protective sleeve, and the other end of the fiber optic segment 1.1 extends out of the protective sleeve;

[0045] Metal tube 4, one end is fixed to one end of the protective sleeve, the fiber core 1 passes through the center of the metal tube 4, and the metal tube 4 is fixed to the fiber core 1;

[0046] The metal tube 4 is filled with a filler protection part for protecting the fiber core 1, and the filler protection part fixes the metal tube 4 to the fiber core 1;

[0047] The metal substrate 7 is fixedly connected to the other end of the metal tube 4. The metal substrate 7 is used to fix the steel wire 8, and the grating section 1.2 is fixed on the metal substrate 7.

[0048] In use, the metal tube 4 and the metal substrate 7 are fixed. The two ends of the protective sleeve on the optical fiber core 1 are stripped, so that the grating section 1.2 at one end of the optical fiber core 1 and the optical fiber section 1.1 at the other end of the optical fiber core 1 are exposed outside the two ends of the protective sleeve. The grating section 1.2 passes through the metal tube 4 and is fixed on the surface of the metal substrate 7. A filler protection part is filled between the metal tube 4 and the optical fiber core 1, and the metal tube 4 and the optical fiber core 1 are fixed through the filler protection part. The metal tube 4 and the protective sleeve are fixed to obtain the sensor of the present invention. The metal substrate 7 and the steel wire 8 are fixed to realize the layout of the sensor of the present invention. Compared with the traditional technology, the present invention innovatively adopts the transmission path of "steel wire - metal substrate - grating", which improves the strain transmission efficiency.

[0049] As an optional implementation manner, the protective sleeve is the drop wire 2. The drop wire 2 is wrapped outside the optical fiber core 1. One end of the grating section 1.2 extends out of the drop wire 2, and the other end of the optical fiber section 1.1 extends out of the drop wire 2.

[0050] As an optional implementation manner, the metal tube 4 and the drop wire 2 are fixed through the optical fiber heat shrinkable tube 3;

[0051] One end of the optical fiber heat shrinkable tube 3 is sleeved outside one end of the drop wire 2, and the other end of the optical fiber heat shrinkable tube 3 is sleeved outside one end of the metal tube 4. After the optical fiber heat shrinkable tube 3 is heated and shrunk, it is fixed to the metal tube 4 and the drop wire 2 respectively.

[0052] As an optional implementation manner, the filler protection part includes the protective polyurea asphalt glue 5. The protective polyurea asphalt glue 5 is filled inside the metal tube 4. The protective polyurea asphalt glue 5 is located between the optical fiber core 1 and the metal tube 4. The optical fiber core 1 is fixed to the metal tube 4 through the protective polyurea asphalt glue 5.

[0053] As an optional implementation manner, the grating section 1.2 is pasted on the metal substrate 7 through the long-term paste glue 6.

[0054] As an optional implementation manner, the metal substrate 7 and the steel wire 8 are welded and fixed.

[0055] The metal substrate 7 is spot-welded and fixed on the surface of the steel wire 8 through a portable lithium battery spot welder. The welding position is on the metal substrate 7 and on the left and right sides of the metal tube 4. The welding points are symmetrically and evenly distributed.

[0056] The thickness of the metal substrate 7 is 0.05 mm - 0.1 mm.

[0057] Before welding, the surface of the steel wire 8 is cleaned and pretreated to remove impurities such as oil stains and oxides.

[0058] The metal substrate 7 is connected to the steel wire 8 by spot welding, and the two are closely attached. The welding points are evenly distributed, resulting in better installation stability, good sensing sensitivity, and higher strain measurement accuracy.

[0059] As an alternative embodiment, the optical fiber heat shrinkable tube 3 is made of polyolefin.

[0060] As an alternative embodiment, the drop wire 2 is made of polyimide.

[0061] The drop wire 2 is made of polyimide with high temperature resistance, good durability and flexibility, making the drop wire fiber grating spot welding type strain sensor have better durability, suitable for strain monitoring requirements in a variety of complex environments, and longer service life.

[0062] As an alternative embodiment, the metal tube 4 is a stainless steel tube;

[0063] The metal substrate 7 is welded and fixed to the metal tube 4;

[0064] The wall thickness of the metal tube 4 is 0.5 mm - 1 mm.

[0065] A drop wire fiber grating spot welding type strain sensor disclosed by the present invention includes a fiber core 1, a drop wire 2, an optical fiber heat shrinkable tube 3, a metal tube 4, a protective polyurea asphalt glue 5, a long-term adhesive glue 6, a metal substrate 7 and a steel wire 8, wherein the fiber core 1 includes an optical fiber section 1.1 and a grating section 1.2.

[0066] Wherein, one end of the drop wire 2 is a connector, and the other end of the drop wire 2 is the fiber core 1 left after removing the protective sleeve of the drop wire; the fiber core 1 is composed of an optical fiber section 1.1 and a grating section 1.2 connected to each other; the drop wire 2 serves as a protective sleeve for the optical fiber section 1.1 and the grating section 1.2 of the fiber core 1.

[0067] The drop wire 2 is made of polyimide with high temperature resistance, good durability and flexibility.

[0068] The optical fiber heat shrinkable tube 3 is heated by a hot air shrink gun at an appropriate distance to cause the optical fiber heat shrinkable tube 3 to shrink and be closely connected to the drop wire 2 and the metal tube 4.

[0069] The optical fiber heat shrinkable tube 3 is made of polyolefin with a working temperature range usually between -55°C and 125°C.

[0070] The metal tube 4 is a stainless steel tube with a thickness of 0.5 mm to 1 mm, and is filled with a protective polyurea asphalt glue 5 therein.

[0071] The metal tube 4 is closely connected to the metal substrate 7 with a thickness of 0.05 mm to 0.1 mm by welding.

[0072] The grating section 1.2 is closely pasted and connected to the metal substrate 7 by the long-term adhesive glue 6.

[0073] The long-term adhesive glue 6 is the long-term 353ND glue with high reliability and durability.

[0074] Furthermore, as a variation of the present invention, the steel wire 8 of the skin fiber optic grating spot welding type strain sensor is welded by a 3V to 5V spot welder. The steel wire 8 can also be a prestressed steel strand, prestressed tendon, etc. Any technical solution identical or similar to the present invention falls within the protection scope of the present invention.

[0075] A manufacturing method of a skin fiber optic grating spot welding type strain sensor, used for manufacturing the above-mentioned skin fiber optic grating spot welding type strain sensor, includes the following steps:

[0076] Fix the metal tube 4 and the metal substrate 7.

[0077] Strip the two ends of the protective sleeve on the fiber core 1, so that the grating section 1.2 at one end of the fiber core 1 and the optical fiber section 1.1 at the other end of the fiber core 1 are exposed outside the two ends of the protective sleeve.

[0078] Pass the grating section 1.2 through the metal tube 4 and fix it on the surface of the metal substrate 7.

[0079] Fill a filler protection part between the metal tube 4 and the fiber core 1, and fix the metal tube 4 and the fiber core 1 through the filler protection part.

[0080] Fix the metal tube 4 and the protective sleeve.

[0081] Compared with the prior art, it has the following beneficial effects:

[0082] 1. High strain transfer efficiency. The strain transfer path of the present invention is "steel wire - metal substrate - grating", and the strain transfer efficiency is higher than that of the traditional one, and the measurement result is more accurate.

[0083] 2. Good installation stability. The present invention connects the sensor and the steel wire in a spot welding manner, the two are closely attached, and the welding points are evenly distributed, so the installation stability is better, with good sensing sensitivity and higher strain measurement accuracy.

[0084] 3. It can improve durability and service life. The skin wire in the present invention is made of polyimide with high temperature resistance, good durability and flexibility, so that the skin fiber optic grating spot welding type strain sensor has better durability, is suitable for the strain monitoring requirements in various complex environments, and has a longer service life.

[0085] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0086] The embodiments described above are only for describing the preferred embodiments of the present invention, rather than limiting the scope of the present invention. Without departing from the spirit of the design of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. The spot welding type strain sensor of a fiber optic grating in a drop wire, characterized in that, Comprising: A core (1), the outside of the core (1) is wrapped with a protective sleeve, the core (1) includes an optical fiber section (1.1) and a grating section (1.2), one end of the grating section (1.2) extends out of the protective sleeve, and the other end of the optical fiber section (1.1) extends out of the protective sleeve; A metal tube (4), one end of which is fixed to one end of the protective sleeve, the core (1) passes through the center of the metal tube (4), and the metal tube (4) is fixed to the core (1); The metal tube (4) is filled with a filler protection part for protecting the core (1), and the filler protection part fixes the metal tube (4) to the core (1); A metal substrate (7) is fixedly connected to the other end of the metal tube (4), the metal substrate (7) is used for fixing to a steel wire (8), and the grating section (1.2) is fixed on the metal substrate (7); The thickness of the metal substrate (7) is 0.05 mm - 0.1 mm.

2. The fiber optic cable grating spot welding type strain sensor according to claim 1, wherein: The protective sleeve is a ribbon fiber (2), the ribbon fiber (2) is wrapped outside the core (1), one end of the grating section (1.2) extends out of the ribbon fiber (2), and the other end of the optical fiber section (1.1) extends out of the ribbon fiber (2).

3. The fiber optic grating spot welding type strain sensor for drop wires according to claim 2, wherein: The metal tube (4) and the ribbon fiber (2) are fixed by an optical fiber heat shrinkable tube (3); One end of the optical fiber heat shrinkable tube (3) is sleeved outside one end of the ribbon fiber (2), the other end of the optical fiber heat shrinkable tube (3) is sleeved outside one end of the metal tube (4), and after the optical fiber heat shrinkable tube (3) is heated and shrunk, it is fixed to the metal tube (4) and the ribbon fiber (2) respectively.

4. The fiber optic cable grating spot welding type strain sensor according to claim 1, characterized in that: The filler protection part includes a protective polyurea asphalt glue (5), the protective polyurea asphalt glue (5) is filled inside the metal tube (4), the protective polyurea asphalt glue (5) is located between the core (1) and the metal tube (4), and the core (1) is fixed to the metal tube (4) through the protective polyurea asphalt glue (5).

5. The fiber optic cable grating spot welding type strain sensor according to claim 1, characterized in that: The grating section (1.2) is pasted on the metal substrate (7) by a long-term pasting glue (6).

6. The fiber optic cable grating spot welding type strain sensor according to claim 1, characterized in that: The metal substrate (7) and the steel wire (8) are fixed by welding.

7. The fiber optic cable grating spot welding type strain sensor according to claim 3, characterized in that: The optical fiber heat shrinkable tube (3) is made of polyolefin material.

8. The fiber optic cable grating spot welding type strain sensor according to claim 1, wherein: The ribbon fiber (2) is made of polyimide material.

9. The fiber optic cable grating spot welding type strain sensor according to claim 1, characterized in that: The metal tube (4) is a stainless steel tube; The metal substrate (7) and the metal tube (4) are fixed by welding; The wall thickness of the metal tube (4) is 0.5 - 1 mm.

10. Method for manufacturing a skin fiber optic grating spot welding type strain sensor, used for manufacturing the skin fiber optic grating spot welding type strain sensor according to any one of claims 1-9, characterized in that, Including the following steps: Fix the metal tube (4) and the metal substrate (7); Strip both ends of the protective sleeve on the core (1) to expose the grating section (1.2) at one end of the core (1) and the optical fiber section (1.1) at the other end of the core (1) outside both ends of the protective sleeve; Make the grating section (1.2) pass through the metal tube (4) and then fix it on the surface of the metal substrate (7); Fill the filler protection part between the metal tube (4) and the core (1), and fix the metal tube (4) to the core (1) through the filler protection part; Fix the metal tube (4) and the protective sleeve.

Images