Intelligent bolt capable of monitoring pre-tightening force
By integrating thin-film piezoelectric sensors on intelligent bolts and using ultrasonic transmission and pulse signal processing, the problem of difficulty in monitoring bolt preload in the existing technology is solved, and high-precision and low-cost preload monitoring and early warning functions are realized .
Patent Information
- Application Number
- CN202420962218.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-07
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-05-07
AI Technical Summary
The prior art is difficult to effectively monitor and early warning of the preloading force of bolts, resulting in unsafe and unstable connection problems.
A smart bolt with integrated thin-film type piezoelectric sensor is designed. Through ultrasonic transmission and pulse signal processing, the preload force of the bolt can be monitored in real time. The film electrode, protective layer and piezoelectric film are used to convert voltage and ultrasonic waves into each other, and judge the The amount of preload of the bolt.
It realizes accurate monitoring of bolt preload, has the advantages of high accuracy, environmental resistance, no distortion, and low cost, and can effectively warn of problems of excessive or too small preload.
Smart Images
Figure CN222141753U_ABST
Abstract
Description
Technical Field
[0001] The utility model provides an intelligent bolt capable of monitoring pre-tightening force, belonging to the field of structural health monitoring or non-destructive monitoring. Background Art
[0002] Bolts are commonly used and important components for connecting various structures in modern industry. Too much or too little preload will cause unsafe and unstable factors. Therefore, monitoring the early warning force of bolts is very important. Utility Model Content
[0003] In view of the above technical problems, the utility model provides an intelligent bolt capable of monitoring pre-tightening force, which can monitor the early warning force of the bolt.
[0004] The specific technical solution is:
[0005] An intelligent bolt capable of monitoring pre-tightening force comprises a bolt head, a lower end surface of the bolt head is connected to a screw rod, and a thread is arranged on the screw rod;
[0006] The upper end surface of the bolt head is provided with a concentric connector groove and a polished surface, wherein the connector groove is arranged on the periphery of the polished surface; a thin film piezoelectric sensor is integrated on the polished surface;
[0007] The thin film piezoelectric sensor comprises, from top to bottom, a thin film electrode, an upper protective layer film, a piezoelectric film, and a lower protective layer film;
[0008] The film electrode is arranged at the axis of the bolt head;
[0009] The radius of the thin film electrode is less than half of the radius of the piezoelectric film.
[0010] The radius of the thin film piezoelectric sensor is less than or equal to the radius of the lower end surface of the screw.
[0011] The polished surface is smooth and parallel and level with the lower end surface of the screw.
[0012] The thin-film type intelligent bolt provided by the utility model has the advantages of environmental tolerance, no signal distortion, higher precision, good repeatability and lower cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a structural schematic diagram of the utility model;
[0014] Figure 2 It is a schematic diagram of the structure of the thin film piezoelectric sensor of the utility model. DETAILED DESCRIPTION
[0015] The structure of the utility model is described in conjunction with the accompanying drawings.
[0016] like Figure 1 As shown, a smart bolt capable of monitoring preload includes a bolt head 3, the lower end surface of the bolt head 3 is connected to a screw rod 2, and the screw rod 2 is provided with a thread 1; the size and material of the bolt head 3, the screw rod 2, and the thread 1 will affect the ultrasonic transmission time. Bolts of different sizes and materials need to be processed separately, while bolts of the same size only need to process the data of one of the bolts.
[0017] The upper end face of the bolt head 3 is provided with a concentric connector groove 4 and a polished surface 5, wherein the connector groove 4 is arranged on the periphery of the polished surface 5; a thin film piezoelectric sensor is integrated on the polished surface 5; the width and depth of the connector groove 4 can be changed according to the connector of the pulse signal generator\receiver.
[0018] like Figure 2 As shown, the thin film piezoelectric sensor includes a thin film electrode 9, an upper protective film 8, a piezoelectric film 7, and a lower protective film 6 from top to bottom; the upper protective film 8, the piezoelectric film 7, and the lower protective film 6 have equal radii, overlap and stack, and the radius of the thin film piezoelectric sensor must be less than or equal to the radius of the lower end face of the screw 2. The upper protective film 8 and the lower protective film 6 are used to protect the piezoelectric film 7 and prevent it from being corroded or otherwise damaged in the environment.
[0019] The thin film electrode 9 is arranged at the axis of the bolt head 3; the radius of the thin film electrode 9 is generally smaller than half of the radius of the piezoelectric film 7, and the material, radius, and thickness (not exceeding 0.1 mm) can be selected according to the usage scenario. The thin film piezoelectric sensor is integrated on the bolt and can realize the mutual conversion between voltage and ultrasonic wave, which is the core of the smart bolt.
[0020] The surface of the polishing surface 5 needs to be mirror-polished and parallel to the lower end surface of the screw 2 .
[0021] The piezoelectric film 7 will produce a small deformation when an external voltage is applied, and will generate a small voltage when an external force is applied.
[0022] The external pulse signal generator and receiver are connected to the connector groove 4 through a connecting line, and a square wave signal is input to the bolt, and the piezoelectric film 7 will continuously vibrate and emit ultrasonic waves.
[0023] The ultrasonic wave will propagate downward, passing through the bolt head 3 and the screw rod 2 in turn, and will be reflected to form an echo when it reaches the bottom of the screw rod 2. The echo will propagate upward along the screw rod 2 and the bolt head 3 in turn, and when it acts on the piezoelectric film 7, it will generate a pulse voltage that is transmitted to the pulse signal generator to read the echo signal.
[0024] When the bolt is installed on the structure, a preload is generated, and the time for the ultrasonic wave to propagate in the bolt is proportional to the warning force. The size of the preload can be determined by testing the difference in echo transmission time between the bolt without preload when it is not installed and the bolt with preload when it is installed on the structure.
Claims
1. A smart bolt capable of monitoring pre-tightening force, comprising a bolt head (3), the lower end surface of the bolt head (3) being connected to a screw rod (2), and the screw rod (2) being provided with a thread (1); It is characterized in that The upper end surface of the bolt head (3) is provided with a concentric connecting head groove (4) and a polishing surface (5), wherein the connecting head groove (4) is arranged on the periphery of the polishing surface (5); and a thin film piezoelectric sensor is integrated on the polishing surface (5).
2. The smart bolt capable of monitoring preload force according to claim 1, characterized in that: The thin film piezoelectric sensor comprises, from top to bottom, a thin film electrode (9), an upper protective layer film (8), a piezoelectric film (7), and a lower protective layer film (6); The film electrode (9) is arranged at the axis center of the bolt head (3).
3. The smart bolt capable of monitoring preload force according to claim 2, characterized in that: The radius of the thin film electrode (9) is less than half the radius of the piezoelectric film (7).
4. The smart bolt capable of monitoring preload force according to claim 1, characterized in that: The radius of the thin film piezoelectric sensor is less than or equal to the radius of the lower end surface of the screw (2).
5. The smart bolt capable of monitoring pre-tightening force according to claim 1, characterized in that: The polished surface (5) is smooth and parallel and horizontal to the lower end surface of the screw (2).