A method for detecting the filling degree of a tension clamp paste and a portable detector
By using a portable testing instrument to acquire vibration signals and temperature data of tension clamps through a tapping method, and combining it with a multivariate mapping model, the problem of the difficulty in quickly and non-destructively testing the grease filling degree of tension clamps is solved. This achieves rapid, non-destructive, on-site testing results, which are suitable for intelligent power grid inspection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GANSU ELECTRIC POWER RES INST TECH CENT CO LTD
- Filing Date
- 2025-06-09
- Publication Date
- 2026-07-14
AI Technical Summary
Existing technologies are difficult to quickly and non-destructively test the filling degree of tension wire clamps. Traditional methods are inefficient and highly destructive, and existing non-destructive testing technologies suffer from problems such as bulky equipment, high cost, radiation safety hazards, or reliance on insufficient human experience.
Design a portable testing instrument that combines the impact method to acquire vibration signals and temperature data, and uses a multivariate mapping model to detect the filling degree of grease in real time. It uses a piezoelectric force sensor, vibration sensor and temperature probe to acquire the vibration frequency, decay time and temperature of the tension clamp, and combines a convolutional neural network to establish a data mapping model to achieve non-destructive testing.
It enables rapid, non-destructive, on-site testing of the grease filling degree of tension clamps, avoiding physical damage to the clamp structure, ensuring the long-term reliability of power lines, and is suitable for intelligent power grid inspection.
Smart Images
Figure CN120490300B_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to the detection technology of grease filling degree in tension clamps, and relates to a device and method for detecting the grease filling degree in tension clamps. Background Technology
[0002] With the rapid development of power transmission networks, tension clamps, as key connecting components of overhead lines, directly affect the mechanical strength and electrical performance of the line due to the reliability of the grease filling state within them. Traditional testing methods mainly rely on manual visual inspection, drilling sampling, or offline laboratory analysis, which suffer from drawbacks such as high destructiveness, low efficiency, and lack of real-time feedback. In recent years, non-destructive testing technologies (such as ultrasound and X-ray imaging) have been gradually applied. However, ultrasonic testing is subject to interference from multi-layer interface reflections in the metal clamp structure, making signal interpretation complex, and it lacks sensitivity to the acoustic impedance difference between grease and air. X-ray imaging is bulky, expensive, and poses radiation safety hazards, making it unsuitable for high-altitude or field operations. The simple tapping method relies on human experience to judge sound differences, lacks quantitative indicators, and is prone to misjudgment due to changes in ambient temperature causing the metal's elastic modulus to drift.
[0003] Therefore, developing a method and testing equipment for rapidly determining the grease injection status of tension wire clamps has become a pressing technical challenge for the industry. Summary of the Invention
[0004] The purpose of this invention is to propose a method for detecting the filling degree of tension wire clamp grease, and to design a portable testing instrument.
[0005] The technical solution of this invention: A portable tester for the filling degree of tension wire clamp grease, comprising a striking body, a display screen support, and a handle. The striking body, display screen support, and handle are physically connected. A battery is built into the handle, display screen support, or striking body. A temperature measurement button is provided on the handle or display screen support. The display screen support is equipped with a display screen showing the filling degree, temperature, and battery level. Multi-color LEDs are arranged around the display screen. A memory card slot is located on the top of the striking body. An internal piezoelectric force sensor, vibration sensor, and main controller are located therein. A ring of LEDs is arranged around the upper part. The piezoelectric force sensor measures the filling degree of the tension wire clamp. When the impact force signal exceeds the specified value, the ring LED lights up. A striking head is connected to the end face of the striking body. The striking head is conical with a slightly convex spherical apex. A temperature probe is also connected to one side of the striking body. The temperature probe is connected to the striking body through a spring pin structure. When the striking head strikes, the temperature probe makes close contact with the surface of the tension clamp due to the elasticity of the spring pin. The vibration sensor is used to measure the vibration frequency, and the temperature probe is used to measure the surface temperature of the tension clamp. The main controller is connected to a piezoelectric force sensor, a vibration sensor, a temperature measuring key, a display screen, a temperature probe, a ring LED, and multi-color LEDs.
[0006] Furthermore, the handle surface is provided with anti-slip silicone texture, and the temperature measuring button has a circular recessed design.
[0007] Preferably, the battery is a rechargeable lithium battery that is charged via a Type-C interface.
[0008] The display screen is preferably an OLED screen, tilted 30° toward the user, and a buzzer is provided on the side of the display screen to emit sound when an abnormality is detected.
[0009] Furthermore, the striking head and the striking body are detachably connected, such as by a magnetic connection.
[0010] A method for detecting the grease filling degree of tension wire clamps involves obtaining the dominant frequency of the vibration signal from the impact on the tension wire clamp using a tapping method, simultaneously measuring the surface temperature of the tension wire clamp, and establishing a multivariate mapping model between the filling degree F and characteristic parameters: F=g(f1,τ,R) h ,T), where: F - percentage of grease filling in the tension clamp; g - multivariable function; f1 - dominant frequency of the vibration signal, unit: Hz; τ - decay time constant of the vibration signal, representing the time required for the vibration amplitude to decay from the peak value to 37% of the initial value, unit: ms; R h - Percentage of third harmonic energy in total vibration energy; T - Surface temperature of tension clamp (under experimental conditions, ambient temperature is controllable, surface temperature equals ambient temperature), unit: ℃. To eliminate the influence of temperature on the dominant frequency, a compensation formula is set: f 1-comp =f1+ α (TT ref In the formula: f 1-comp This is the temperature-compensated main frequency. α T is the temperature compensation coefficient; ref For reference temperature;
[0011] Method for establishing a multivariate mapping model: Standard tension clamp samples with different filler densities are fabricated. Under different temperature conditions, the f1, τ, and R values of each standard tension clamp sample with different filler densities are measured by tapping. h Record the temperature T, and input the test data into a convolutional neural network for training and validation to obtain f1, τ, R. h The mapping relationship between T and F is created into a data mapping model and stored in the main controller. A striking device is constructed, which is equipped with a piezoelectric force sensor, a vibration sensor, a temperature probe, and a main controller. The striking device strikes the tension clamp, and the vibration sensor and temperature probe obtain f1 and T signals. The main controller receives the f1 and T signals, calls the data mapping model, and obtains the fill degree F through data processing, which is then displayed on the screen of the striking device.
[0012] Specifically, the fill percentage gradients of the standard model tension clamp samples are 0%, 25%, 50%, 75%, and 100%, with at least 5 samples for each gradient. The ambient temperature is controlled by a temperature control chamber, with temperature gradients of -20℃, 0℃, 25℃, and 50℃. The main frequency of the vibration signal is obtained using a standard impact hammer and vibration sensor. The vibration signal of each sample at each temperature is measured repeatedly 10 times and the average value is taken.
[0013] Preferably, the vibration sensor is a MEMS accelerometer, encapsulated in the striking device, and the temperature probe is a PT100 patch temperature sensor, connected to the temperature probe with an elastic connector, making close contact to measure the surface temperature of the tension clamp.
[0014] Furthermore, after the device is powered on, it automatically performs zero-point calibration. Place the temperature probe vertically against the surface of the tension clamp, ensuring that there is no dirt in the contact area of the temperature probe. Press and hold the temperature measurement button for 3 seconds, and release it after the temperature reading stabilizes. Tap the tension clamp with natural force, and the vibration signal will automatically trigger the acquisition. If the force is insufficient or excessive, it will prompt you to try again.
[0015] An improvement could be made by incorporating a memory card into the striking device to store the test results.
[0016] The beneficial effects of this invention are as follows: By quantifying the dominant frequency, decay time, and harmonic characteristics of vibration signals, and combining this with a temperature dynamic correction model, the invention eliminates the need for drilling, disassembly, or contact with the grease. Testing can be completed simply by external tapping, avoiding physical damage to the clamp structure caused by traditional methods. This ensures the long-term reliability of power lines and enables rapid, on-site testing of the grease filling degree of tension clamps. It effectively fills a current technological gap and has significant engineering application value. This invention aligns with the technological upgrade needs of intelligent power grid inspection, providing an innovative solution to the challenge of on-site diagnosis of hidden defects in tension clamps. Attached Figure Description
[0017] Figure 1 This is an overall schematic diagram of the portable detector of the present invention;
[0018] Figure 2 This is a display information diagram of the portable detector of the present invention.
[0019] In the diagram: 1-Handle, 2-Temperature sensor, 3-Display support, 4-Display, 5-Tapping body, 6-Piezoelectric force sensor, 7-Vibration sensor, 8-Tapping head, 9-Temperature probe, 10-Ring LED, 11-Multi-color LED, 12-Memory card slot, 13-Type-C interface, 14-Buzzer. Detailed Implementation
[0020] As shown in the figure, the portable tester for the filling degree of tension clamp grease includes a striking body 5, a display screen support 3, and a handle 1. The striking body 5, the display screen support 3, and the handle 1 are connected by physical structure (such as threads, snaps, one-piece molding, etc.).
[0021] The handle 1 has a built-in battery, and the display support 3 has a temperature measurement button 2. The surface of the handle 1 is designed with a non-slip silicone texture. It has a built-in rechargeable lithium battery and a Type-C interface 13 on one end. The temperature measurement button 2 is designed with a circular recessed design (to prevent accidental touches) and the button is located at the natural position of the thumb.
[0022] The display support 3 houses the display screen 4, which displays fill level, temperature, and battery level. An OLED screen is preferred, and the screen is tilted 30° towards the user for easy viewing by testing personnel. A buzzer 14 is located on the side of the display screen, emitting a differentiated beep when an abnormality is detected. Multi-color LED lights 11 are arranged around the display screen 4.
[0023] The top of the striking body 5 is equipped with a memory card slot 12, which uses a Micro-SD card. Inside, there is a piezoelectric force sensor 6, a vibration sensor 7, and a main controller. A ring LED 10 is arranged around the upper part. The piezoelectric force sensor 6 measures the striking force. When the striking force signal exceeds the specified value, the ring LED 10 flashes.
[0024] A striking head 8 is attached to the end face of the striking body 5, and the striking head 8 and the striking body 5 can be detachably and movably connected. The striking head 8 is conical, and the top of the cone is a slightly convex spherical surface. The striking head 8 is made of cylindrical hardened steel (two specifications with diameters of 10 / 15mm), and adopts a magnetic design for easy replacement. The slightly convex spherical surface at the front end ensures point contact with the surface of the wire clamp during striking.
[0025] A temperature probe 9 is also connected to one side of the striking body 5. The temperature probe 9 is connected to the striking body 5 via a spring-loaded pin structure. When the striking head 8 strikes, the temperature probe 9 relies on the elasticity of the spring-loaded pin to make close contact with the surface of the tension clamp, ensuring thermal contact with the tension clamp surface. The spring-loaded pin is achieved by installing the tail of the probe in a sleeve, with a spring connected to the bottom of the sleeve, allowing the temperature probe to extend and retract within a certain range.
[0026] The main controller connects to a piezoelectric force sensor 6, a vibration sensor 7, a temperature measuring key 2, a display screen 4, a temperature probe 9, a ring LED 10, and a multi-color LED 11. The vibration sensor 7 measures the vibration frequency and transmits the signal to the main controller. The temperature probe 9 measures the surface temperature of the tension clamp and transmits the temperature signal to the main controller. The temperature probe uses a PT100 surface-mount temperature sensor. The piezoelectric force sensor 6 generates a signal, which the main controller receives, compares, and, if the value exceeds the specified limit, illuminates the ring LED 10.
[0027] The main controller processes the data to determine the fill degree and sends an electrical signal to the display screen 4. Simultaneously, it sends a lighting signal to the corresponding color light-emitting unit of the multi-color LED 11 according to the fill degree threshold. The multi-color LED 11 has three colors: green, yellow, and red. It displays different colors according to the fill degree threshold. Users can obtain the corresponding fill degree range for a certain color through the instruction manual.
[0028] The principle of the method for testing the filling degree of tension wire clamp grease:
[0029] 1. When the grease filling inside the tension clamp is insufficient, the internal voids will affect the overall stiffness and damping characteristics of the structure. Tapping the tension clamp body will cause significant changes in parameters such as its vibration frequency and decay time. The tension clamp can be simplified as a multi-layered composite shell structure (outer metal shell + inner grease filling layer). When the grease filling is insufficient, the internal cavity forms a "soft support."
[0030] ① According to the bending vibration equation of a beam, the natural frequency f n With stiffness k and equivalent quality m satisfy: Reduced fat leads to k Decline, at the same time m The decrease in stiffness is the dominant characteristic, and the overall frequency shifts towards lower frequencies.
[0031] ② As a viscoelastic material, grease can increase the system's damping ratio ζ, and the decay time constant T is inversely proportional to ζ: T∝1 / ζ ω n , ω n Indicates the natural angular frequency. ω n = 2π f n When the filling of the ointment is insufficient, the damping decreases and the decay time is prolonged.
[0032] By tapping the surface of the wire clamp (non-destructively), vibration signals are collected using an accelerometer or microphone, and characteristic parameters such as the dominant frequency, vibration amplitude decay rate, and harmonic distribution are extracted.
[0033] 2. An ambient temperature sensor is introduced to establish a temperature-material elastic modulus correction model to eliminate the influence of temperature on the vibration characteristics of the metal wire clamp. The elastic modulus E of the metal wire clamp changes with temperature, causing the dominant frequency to decrease with increasing temperature at the same filler density. This interference needs to be eliminated through temperature compensation. The temperature compensation algorithm is as follows:
[0034] ① Establish a multivariate mapping model between fill degree F and feature parameters: F=g(f1,τ,R) hIn the formula: F - the filling degree of grease in the tension clamp (percentage); g - a multivariable function; f1 - the dominant frequency of the vibration signal (unit: Hz); τ - the decay time constant of the vibration signal (representing the time required for the vibration amplitude to decay from the peak value to 37% of the initial value, unit: ms); R h - Harmonic energy ratio (the percentage of third harmonic energy in total vibration energy); T - Surface temperature of tension clamp (unit: °C).
[0035] ② The effect of temperature on the main frequency is approximately linear, and the compensation formula is: f 1-comp =f1+ α (TT ref In the formula: f 1-comp This indicates the main frequency after temperature compensation; α T is the temperature compensation coefficient; ref This is a reference temperature.
[0036] Methods for establishing multivariate mapping models:
[0037] S1: Select standard model tension clamps and prepare filler gradient samples: 0%, 25%, 50%, 75%, 100%, with at least 5 samples for each gradient. Verify the actual filler density using industrial CT scans.
[0038] S2: Set a temperature gradient (-20℃, 0℃, 25℃, 50℃) in the temperature control chamber. Use a standard impact hammer and vibration sensor to collect the vibration signal of each sample at each temperature, repeating 10 times and taking the average value. (The tension clamp samples should be placed in the temperature control chamber for a period of time to allow their temperature to reach equilibrium with the temperature inside the chamber. Once the surface temperature of the tension clamp is equal to the temperature inside the chamber, the temperature inside the chamber can be recorded directly without measuring the surface temperature of the tension clamp.)
[0039] S3: Extract f1, τ, R for each signal h And combine it with temperature T to form an input vector, and label the corresponding fill degree F;
[0040] S4: Take the previously obtained test data and the four-dimensional vector f1,τ,R h The input T is used to train and validate the convolutional neural network, resulting in f1,τ,R. h The mapping relationship between T and F is created as a data mapping model. The data mapping model is stored in the main controller.
[0041] The main controller is installed in the filler measurement device—a portable detector. The main controller's data mapping model responds to the main frequency of the vibration signal measured by the filler measurement device and the surface temperature of the tension clamp, and calculates and outputs the filler degree.
[0042] Specific operation of portable detector:
[0043] 1. After powering on, the zero-point calibration is automatically performed (the probe is suspended and tapped to collect ambient noise and subtract the substrate).
[0044] 2. Place the temperature probe vertically against the surface of the clamp, ensuring that the contact area of the temperature sensor is free of dirt. Press and hold the temperature measurement button for 3 seconds, and release it after the temperature reading stabilizes.
[0045] 3. Use a handheld portable tester to tap the tension clamp with natural force (the vibration signal will automatically trigger the acquisition; if the force is insufficient or excessive, a ring LED will light up to indicate a retry).
[0046] 4. When the tapping force is appropriate, the display screen shows the fill percentage (e.g., "95%), and the multi-color LED lights simultaneously display the color status.
[0047] 5. Data storage and export: Test results are automatically stored to a Micro-SD card.
Claims
1. A method for detecting the filling degree of tension clamp grease, wherein a portable detector for the filling degree of tension clamp grease is used. The portable detector for the filling degree of tension clamp grease includes a striking body (5), a display screen support (3), and a handle (1). The striking body (5), the display screen support (3), and the handle (1) are connected by a physical structure. The handle (1), the display screen support (3), or the striking body (5) has a built-in battery. The handle (1) or the display screen support (3) is provided with a temperature measuring key (2). The display screen support (3) is provided with a display screen (4) to display the filling degree, temperature, and power. Multi-color LED lights (11) are provided around the display screen (4). The top of the striking body (5) is provided with a memory card slot (12). Inside, there are piezoelectric force sensors (6), vibration sensors (7), and a main controller. The upper part is surrounded by a ring of LEDs. (10), the piezoelectric force sensor (6) measures the striking force. When the striking force signal exceeds the specified value, the ring LED (10) lights up. The striking head (8) is connected to the end face of the striking body (5). The striking head (8) is conical and the top of the cone is a slightly convex spherical surface. A temperature probe (9) is also connected to one side of the striking body (5). The temperature probe (9) is connected to the striking body (5) through a spring pin structure. When the striking head (8) strikes, the temperature probe (9) relies on the elasticity of the spring pin to make close contact with the surface of the tension clamp. The vibration sensor (7) is used to measure the vibration frequency, and the temperature probe (9) is used to measure the surface temperature of the tension clamp. The main controller is connected to the piezoelectric force sensor (6), vibration sensor (7), temperature measuring key (2), display screen (4), temperature probe (9), ring LED (10) and multi-color LED light (11). Its characteristics are: The dominant frequency of the vibration signal from the impact on the tension clamp was obtained by the impact method, and the surface temperature of the tension clamp was measured simultaneously. A multivariate mapping model between the filling degree F and the characteristic parameters was established: F=g(f1,τ,R) h ,T), where: F - the filling degree of grease in the tension clamp; g - a multivariable function; f1 - the dominant frequency of the vibration signal, in Hz; τ - the decay time constant of the vibration signal, in ms; R h - Percentage of third harmonic energy in total vibration energy; T - Surface temperature of tension clamp, unit: °C. To eliminate the influence of temperature on the dominant frequency, a compensation formula is set: f 1-comp =f1+ α (TT ref In the formula: f 1-comp This is the temperature-compensated main frequency. α T is the temperature compensation coefficient; ref For reference temperature; Method for establishing a multivariate mapping model: Standard tension clamp samples with different filler densities are fabricated. Under different temperature conditions, the f1, τ, and R values of each standard tension clamp sample with different filler densities are measured by tapping. h Record the temperature T, and input the test data into a convolutional neural network for training and validation to obtain f1, τ, R. h The mapping relationship between T and F is created into a data mapping model and stored in the main controller. A striking device is constructed, which is equipped with a piezoelectric force sensor, a vibration sensor, a temperature probe, and a main controller. The striking device strikes the tension clamp, and the vibration sensor and temperature probe obtain f1 and T signals. The main controller receives the f1 and T signals, calls the data mapping model, and obtains the fill degree F through data processing, which is then displayed on the screen of the striking device.
2. The method for detecting the filling degree of tension wire clamp grease according to claim 1, characterized in that, The filling gradient of the standard model tension clamp samples is 0%, 25%, 50%, 75%, and 100%, with at least 5 samples for each gradient. The ambient temperature is controlled by a temperature control chamber, with temperature gradients of -20℃, 0℃, 25℃, and 50℃. The main frequency of the vibration signal is obtained using a standard impact hammer and vibration sensor. The vibration signal of each sample at each temperature is measured repeatedly 10 times and the average value is taken.
3. The method for detecting the filling degree of tension wire clamp grease according to claim 2, characterized in that, The vibration sensor uses a MEMS accelerometer, which is encapsulated in the impact device. The temperature probe uses a PT100 patch temperature sensor, which is connected to the temperature probe with an elastic connector to measure the surface temperature of the tension clamp in close contact.
4. The method for detecting the filling degree of tension wire clamp grease according to claim 3, characterized in that, After the device is powered on, it will automatically perform zero-point calibration. Place the probe vertically against the surface of the tension clamp, ensuring that there is no dirt in the contact area of the temperature probe. Press and hold the temperature measurement button for 3 seconds, and release it after the temperature reading stabilizes. Tap the tension clamp with natural force, and the vibration signal will automatically trigger the acquisition. If the force is insufficient or excessive, it will prompt you to try again.
5. The method for detecting the filling degree of tension wire clamp grease according to claim 4, characterized in that, The striking device is equipped with a memory card, which stores the test results.
6. The method for detecting the filling degree of tension wire clamp grease according to claim 1, characterized in that: The handle (1) has a non-slip silicone texture on its surface, and the temperature measuring key (2) has a circular recessed design.
7. The method for detecting the filling degree of tension wire clamp grease according to claim 1, characterized in that... The battery is a rechargeable lithium battery, which is charged by connecting to a Type-C interface (13).
8. The method for detecting the filling degree of tension wire clamp grease according to claim 1, characterized in that... The display screen is an OLED screen, tilted 30° towards the user, and a buzzer is located on the side of the display screen to emit sound when an abnormality is detected.
9. The method for detecting the filling degree of tension wire clamp grease according to claim 1, characterized in that: The striking head (8) and the striking body (5) are detachably connected by magnetic attraction.