An intelligent bolt based on a fiber optic optical coherence sensor

Abstract

The present invention discloses an intelligent bolt based on a fiber optic optical coherence sensor, which includes a plug structure and an alloy hollow structural member. Thread one and the thread two are respectively machined on the outer surfaces of the upper and lower parts of the alloy hollow structural member. The detection sensor is fixed to the bolt through the thread one and the thread two. The plug structure is fixed on the alloy hollow structural member. The fiber optic optical coherence sensor is fixed on the CrMo alloy hollow structural member through a welding fixing hole. The tail fiber of the fiber optic optical coherence sensor is fixed in the inner hole of the alloy hollow structural member through a connector. An optical fiber ferrule is provided above the connector. In the present invention, the fiber optic optical coherence sensor is placed inside the intelligent bolt monitoring sensor, which can give full play to the advantage of the fiber optic optical coherence sensor in measuring distance with ultra-high precision, and can achieve a measurement accuracy of ±0.05%. It can greatly improve the intelligent monitoring accuracy, linearity and sensitivity of the bolt.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and specifically to an intelligent bolt based on a fiber optic optical coherence sensor. Background Art

[0002] Bolts are the most commonly used connecting parts in large buildings, steel structures, and large equipment, and are widely used. Bolt connection failure has become the main factor affecting the safety of steel structures. Accurate monitoring of the working state of bolts is crucial for the continuous safe operation of equipment. Online real-time monitoring of intelligent bolts can detect the current pre-tightening force value of bolt connections, and conduct fault diagnosis on whether the bolt connections are loose, overloaded, etc. It can give early warnings of potential faults and avoid major accidents. However, there are relatively few effective real-time monitoring means on the market currently.

[0003] In order to solve the technical problems of bolt load and looseness that have long troubled the engineering field. Traditional intelligent bolts use the method of placing strain gauges in the central hole inside the bolt to directly detect the tension of the screw rod. This method fixes the strain gauge in the hole inside the bolt by means of glue filling and binding to detect the telescopic deformation of the screw rod. The use of adhesives causes large temperature offsets, creep, and hysteresis effects in the strain of the screw rod, so it greatly limits the measurement range of the strain gauge and reduces the measurement accuracy.

[0004] Compared with the traditional paste strain gauge sensor, in the intelligent bolt monitoring method based on a fiber optic optical coherence sensor, the reflection element of the fiber optic optical coherence sensor is in direct contact with the bolt, without the need for adhesives, overcoming the hysteresis and creep defects caused by the use of adhesives, and the measurement accuracy can reach ±0.05%. In addition, the fiber optic optical coherence sensor will not break the fiber and has excellent performance in harsh environments, and its outstanding feature is that it is not affected by temperature.

[0005] Currently, the related patents of the intelligent bolt monitoring method based on a fiber optic optical coherence sensor include the Chinese patent "A Wireless Intelligent Bolt for Real-time Monitoring of Pre-tightening Force" with the application number 201910029957.1, which was applied on January 11, 2019. And the Chinese patent "A Bolt State Monitoring Sensor" with the application number CN201320861316.0, which was applied on December 25, 2013. The intelligent bolt monitoring method based on a fiber optic optical coherence sensor is a method with a simple structure, no fiber breakage, low cost, high precision, resistance to high and low temperatures, and real-time online intelligent monitoring of bolts.

[0006] The above-mentioned technology has the following several defects: 1. How to ensure the real-time online intelligent monitoring of bolts; 2. How to achieve the long-term reliability of bolt detection sensors, their reliability during use, resistance to vibration, being unaffected by high and low temperatures, waterproofing, and dustproofing; 3. How to enable the bolt detection sensor to deform synchronously with the bolt and achieve ultra-high measurement accuracy of the sensor; 4. How to achieve low cost and mass production of bolt detection sensors.

[0007] The intelligent bolt based on the fiber optic optical coherence sensor of the present invention can solve the above problems simultaneously. Summary of the Invention

[0008] The purpose of the present invention is to provide an intelligent bolt based on a fiber optic optical coherence sensor to solve the problems raised in the above-mentioned background technology.

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

[0010] An intelligent bolt based on a fiber optic optical coherence sensor includes a plug structure and an alloy hollow structural member. Thread one and the thread two are respectively machined on the outer surfaces of the upper and lower parts of the alloy hollow structural member. The detection sensor is fixed to the bolt through the thread one and the thread two. The plug structure is fixed on the alloy hollow structural member. The fiber optic optical coherence sensor is fixed to the CrMo alloy hollow structural member through a welding fixing hole. The tail fiber of the fiber optic optical coherence sensor is fixed in the inner hole of the alloy hollow structural member through a connector. A fiber optic ferrule is provided above the connector.

[0011] As a further technical solution of the present invention: A fiber optic loose tube is provided outside the tail fiber of the fiber optic optical coherence sensor.

[0012] As a further technical solution of the present invention: The designed height of the fiber optic ferrule is lower than the upper surface of the bolt.

[0013] As a further technical solution of the present invention: A flange is built-in above the connector on the sensor.

[0014] As a further technical solution of the present invention: The upper surface of the plug structure is a reflecting surface.

[0015] As a further technical solution of the present invention: The alloy hollow structural member is a 42CrMo alloy hollow structural member.

[0016] As a further technical solution of the present invention: The connector is a 6mm connector.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By placing the fiber optic optical coherence sensor inside the intelligent bolt monitoring sensor, the advantage of high-precision ranging of the fiber optic optical coherence sensor can be fully utilized, and a measurement accuracy of ±1um can be achieved. This can greatly improve the intelligent monitoring accuracy of bolts.

[0018] 2. The fiber optic optical coherence sensor is used to measure the distance, and then the deformation and pre-tightening force of the bolt are measured. The long-term reliability of the bolt detection sensor is realized, and there will be no fiber breakage, it is resistant to vibration, and is not affected by high and low temperatures during use.

[0019] 3. Since the intelligent bolt monitoring sensor based on fiber optic optical coherence is fixed to the bolt through two threads, synchronous deformation with the bolt can be achieved. This sensor uses 42CrMo alloy, which has the same material as the bolt and can have the same coefficient of thermal expansion.

[0020] 4. Since the fiber optic optical coherence sensor and the 42CrMo alloy hollow structural part are fixed by welding, the mechanical strength is guaranteed.

[0021] 5. The intelligent bolt monitoring method based on the fiber optic optical coherence sensor is simple to operate, can save costs, and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a cross-sectional structure diagram of the intelligent bolt monitoring sensor based on fiber optic optical coherence of the present invention.

[0023] Figure 2 It is an overall structure diagram of the intelligent bolt monitoring sensor based on fiber optic optical coherence of the present invention.

[0024] In the figure: plug structure - 1, thread one - 2, reflecting surface - 3, fiber optic optical coherence sensor - 4, welding fixing hole - 5, thread two - 6, fiber loose tube - 7, alloy hollow structural part - 8, connector - 9, fiber ferrule - 10. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Example 1: Please refer to Figure 1-2, An intelligent bolt based on a fiber optic optical coherence sensor, comprising a plug structure 1 and an alloy hollow structural member 8. Threads 1 and 2 are respectively machined on the outer surfaces of the upper and lower parts of the alloy hollow structural member 8. The detection sensor is fixed to the bolt through the threads 1 and 2. The plug structure 1 is fixed on the alloy hollow structural member 8. The fiber optic optical coherence sensor 4 is fixed on the 42CrMo alloy hollow structural member 8 through the welding fixing hole 5. The tail fiber of the fiber optic optical coherence sensor 4 is fixed in the inner hole of the alloy hollow structural member 8 through the connector 9. Above the connector 9 is provided with an optical fiber ferrule 10.

[0027] The manufacturing process of the present invention is as follows:

[0028] Step 1: Use a 42CrMo alloy hollow structural member as the outer structure, which is precision machined. Since the material of the 42CrMo alloy hollow structure is the same as that of the bolt and has the same coefficient of thermal expansion as the bolt.

[0029] Step 2: Threads 1 and 2 are machined on the outer surface of the 42CrMo alloy hollow structural member. A threaded hole of M6 is drilled at the center position of the bolt to be measured. The detection sensor is fixed to the bolt through threads 1 and 2 and realizes synchronous deformation with the bolt.

[0030] Step 3: The reflecting surface is the upper surface of the plug structure, and the upper surface requires a certain roughness to ensure diffuse reflection. When the coherent sensor and the reflecting surface have a certain angle, the distance measurement can still be realized.

[0031] Step 4: Adjust the angle between the fiber optic optical coherence sensor and the reflecting surface. The plug structure is fixed to the 42CrMo alloy hollow structural member by welding.

[0032] Step 5: Then fix the fiber optic optical coherence sensor to the 42CrMo alloy hollow structural member through the welding fixing hole.

[0033] Step 6: The tail fiber of the fiber optic optical coherence sensor is protected by an optical fiber loose tube to prevent damage to the tail fiber.

[0034] Step 7: The tail fiber of the fiber optic optical coherence sensor is fixed in the inner hole of the 42CrMo alloy hollow structural member through a 6mm connector.

[0035] Step 8: Above the 6mm connector is a position for the optical fiber to come out, that is, the optical fiber ferrule. The designed height of the optical fiber ferrule is lower than the upper surface of the bolt to prevent damage to the optical fiber ferrule during the handling of the bolt.

[0036] Example 2: On the basis of Example 1: A flange is built in above the connector 9 on the sensor. The flange can increase the sealing effect and improve the detection accuracy.

[0037] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0038] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An intelligent bolt based on a fiber optic optical coherence sensor, comprising a plug structure (1), an alloy hollow structural member (8) and a bolt, characterized in that, Thread two (6) and thread one (2) are respectively machined on the outer surfaces of the upper and lower parts of the alloy hollow structural member (8). The alloy hollow structural member (8) is fixed to a bolt through the thread one (2) and the thread two (6). The plug structure (1) is fixed at the lower end of the alloy hollow structural member (8). The fiber optic coherence sensor (4) is fixed in the alloy hollow structural member (8) through the welding fixing hole (5). The tail fiber of the fiber optic coherence sensor (4) is fixed in the inner hole at the upper end of the alloy hollow structural member (8) through the connector (9). An optical fiber ferrule (10) is provided above the connector (9); the upper surface of the plug structure (1) is a reflecting surface (3); the thread one (2) and the thread two (6) are discontinuously distributed, and at least part of the outer wall portion of the hollow structural member (8) between the fiber optic coherence sensor and the plug structure is threadless.

2. The intelligent bolt based on the fiber optic optical coherence sensor according to claim 1, wherein A fiber optic loose tube (7) is provided outside the tail fiber of the fiber optic coherence sensor (4).

3. The intelligent bolt based on the fiber optic optical coherence sensor according to claim 1, characterized in that, The designed height of the optical fiber ferrule (10) is lower than the upper surface of the bolt.

4. The intelligent bolt based on the fiber optic optical coherence sensor according to claim 1, characterized in that, A flange is built in above the connector (9) on the sensor.

5. The intelligent bolt based on the fiber optic optical coherence sensor according to claim 1, characterized in that, The alloy hollow structural member (8) is a 42CrMo alloy hollow structural member.

6. The intelligent bolt based on the fiber optic optical coherence sensor according to claim 5, characterized in that, The connector (9) is a 6 mm connector.

Images