Infrared imaging insulator epoxy resin internal defect detection method and system

Abstract

The invention discloses an infrared imaging insulator epoxy resin internal defect detection method and system, and relates to the technical field of defect detection, and the method comprises the following steps: constructing a to-be-detected epoxy resin model, and heating the epoxy resin model to obtain an imaging time sequence diagram; analyzing the imaging sequence diagram to obtain influence factors of internal defects of the epoxy resin model; and judging influence factors of the internal defects, and determining a detection method of the epoxy resin model according to a judgment result. According to the method, the internal defect information of the basin-type insulator is obtained by utilizing infrared imaging, the defects such as bubbles and cracks in the basin-type insulator are quickly and accurately distinguished by adopting a comprehensive brightness difference standard method, and efficient scanning can be realized in the detection process by adopting array type bubble defect arrangement and accurate model construction; particularly, by constructing a plurality of groups of models with different defect depths and diameters, the system can quickly judge influence factors of different defects, so that the overall scanning efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of defect detection, in particular to an infrared imaging insulator epoxy resin internal defect detection method and system. Background Art

[0002] The pot insulator is a very core component of high-voltage power equipment. It is mainly made of epoxy resin casting and can play an important role in electrical insulation, mechanical support, air chamber isolation, etc. Therefore, the use of various types of methods to detect defects and deterioration trends on the surface and inside of the pot insulator is a key technology to improve the operation of high-voltage power equipment. However, the current defect detection methods such as ultrasound, X-rays, and eddy currents have problems such as complex equipment, poor detection capabilities, poor anti-interference capabilities, and high misdiagnosis rates, which seriously affect the defect detection speed and accuracy of pot insulators, and cannot guarantee the yield rate of pot insulators. It is not suitable for the application and use of pot insulators on actual production lines. The flaw detection work, and the prevention effect of pot insulator deterioration is not ideal.

[0003] In recent years, infrared imaging technology has played an important role in the field of non-destructive testing due to its non-contact, long-distance inspection, strong stability against external obstacles such as smoke and strong wind, and high sensitivity. Infrared imaging technology is divided into active and passive types, among which the active type has better contrast difference and detection resolution. According to the different information collected, different analysis models are used to process the data to obtain defect information such as bubbles and cracks inside the pot insulator.

[0004] However, the existing infrared imaging technology determines the presence of the defect type of the pot-type insulator by converting the difference in spectral characteristics between the defect and the background under infrared conditions into a difference in image characteristics. However, most of them adopt different infrared wavelength imaging fusion detection methods for the size and depth of the defects. Although it can achieve high-precision and high-resolution detection of pot-type insulator defects, there are problems. Specifically, the scanning efficiency is low; the defect size and depth correspond to different wavelength excitations; similar foreign matter imaging has missed detection. The main reason for the above is that the use of a multi-excitation, multi-wavelength imaging system can obtain the characteristics of foreign matter with different multi-wavelength reflection characteristics, but it cannot obtain the characteristics of foreign matter with the same reflection characteristics, and the imaging information obtained is inaccurate. Summary of the invention

[0005] In view of the problems existing in the existing infrared imaging insulator epoxy resin internal defect detection and system, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is that it is difficult to detect internal defects of epoxy resin, and the detected defect positions are not accurate enough.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present invention provides an infrared imaging insulator epoxy resin internal defect detection method, which comprises the following steps:

[0009] constructing an epoxy resin model to be tested, heating the epoxy resin model, and obtaining an imaging timing diagram;

[0010] Analyze the imaging timing diagram to obtain the influencing factors of the internal defects of the epoxy resin model;

[0011] The influencing factors of internal defects are judged, and the detection method of the epoxy resin model is determined based on the judgment results.

[0012] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, when constructing the epoxy resin model, an array of bubble defects is arranged, and the specific arrangement is expressed as follows:

[0013] Create X rows of bubble defects, with Y number of bubble defects in each row;

[0014] The spacing between two adjacent rows of bubble defects is set to x, and the spacing between bubble defects in the same row is set to y;

[0015] The diameter D of each row of bubble defects is set to an increasing trend, and the depth H of the bubble defects in the same row is set to an increasing trend;

[0016] Among them, X>3, Y>3.

[0017] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, the step of heating the epoxy resin model includes:

[0018] Obtaining the number of bubble defects, setting the same number of halogen lamps according to the number of bubble defects, and setting the halogen lamps and the bubble defects of the epoxy resin model in a one-to-one correspondence;

[0019] Set the distance between the halogen lamp and the epoxy resin model;

[0020] Turn on all halogen lamps synchronously and adjust the power of all halogen lamps to the same power;

[0021] An infrared thermal imager is used to capture and record the dynamic evolution of the surface temperature field of the epoxy resin model to obtain an imaging time sequence diagram;

[0022] When recording the dynamic evolution of the surface temperature field of the epoxy resin model, an interval time K is set, and the epoxy resin model is sampled once every K time length until the set total time length is reached, and multiple imaging time sequence diagrams are obtained;

[0023] The brightness of the halogen lamp adopts the comprehensive brightness difference standard method, selects the best infrared wavelength for reflection and transmission, fuses the transmission information with the reflection information, and obtains the characteristic image of the foreign matter of the detected sample. When there are n foreign matters, the calculation formula of the comprehensive brightness difference is expressed as:

[0024]

[0025] Where ΔK(λ) is the comprehensive brightness difference, Δk j (λ) represents the average brightness of the foreign matter, Δk b (λ) represents the average background brightness, j=1, 2, 3, ..., n.

[0026] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, when the epoxy resin model is heated, the propagation function of the heat wave in the cutoff is obtained, and in the rectangular coordinate system, the heat conduction differential equation along the direction (x, y, z) at time t is expressed as:

[0027]

[0028] Under the condition of unsteady heat conduction, the second type of boundary conditions is given:

[0029]

[0030] Substituting into the relationship expression between heat flux and temperature gradient, we get:

[0031]

[0032] Where p is the material density, c is the specific heat capacity, α is the diffusion coefficient of the material, specifically α=λ / pc, pc is the volume heat capacity, specifically the ability of an object to store heat, and f(x,y,z,t) is the heat source function;

[0033] Among them, the relationship between heat flux and temperature gradient is expressed as:

[0034]

[0035] In the formula, q represents the heat flux density, ▽T represents the temperature gradient, λ represents the thermal conductivity of the material, and the negative sign represents that the direction of heat transfer is opposite to the direction of the temperature gradient. Expressed as the rate of change of temperature in a certain direction.

[0036] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, the influencing factors of the internal defects of the epoxy resin model include influencing factors of the same defect diameter with different defect depths and influencing factors of the same defect depth with different defect diameters;

[0037] The method for determining the influencing factors of the same defect diameter at different defect depths includes:

[0038] Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera;

[0039] Construct multiple groups of epoxy resin judgment models with different defect depths and the same defect diameter, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect depths;

[0040] Calculate the temperature difference ΔT between the defect point and the non-defect point at different defect depths S , set the depth difference threshold ΔT′;

[0041] When the temperature difference ΔT S When the depth difference threshold ΔT′ is less than the depth difference threshold ΔT′, it means there is no effect;

[0042] When the temperature difference ΔT S When it is ≥ the depth difference threshold ΔT′, it is considered to be influential;

[0043] The method for determining the influencing factors of the same defect depth with different defect diameters includes:

[0044] Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera;

[0045] Construct multiple groups of epoxy resin judgment models with different defect diameters and the same defect depth, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect diameters;

[0046] Calculate the temperature difference ΔT between the defect point and the non-defect point under different defect diameters Z , set the diameter difference threshold ΔT″;

[0047] When the temperature difference ΔT Z When the diameter difference threshold ΔT″ is less than the diameter difference threshold ΔT″, it means there is no impact;

[0048] When the temperature difference ΔT Z When the diameter difference threshold ΔT″ is greater than or equal to the diameter difference threshold ΔT″, it indicates that there is an impact.

[0049] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, wherein: the influencing factors of the internal defects of the epoxy resin model also include the influencing factors of different halogen lamp opening time;

[0050] The method for determining the influencing factors of the different halogen lamp on-times includes:

[0051] Set the power of the halogen lamp, the capture time of the infrared thermal imager, and the duration of the halogen lamp groups;

[0052] An epoxy resin judgment model is constructed, and the epoxy resin judgment model is heated to obtain a temperature collection graph of different halogen lamp opening times;

[0053] Calculate the temperature difference ΔT between the defective point and the non-defective point under different halogen lamp on-times L , set the duration difference threshold ΔT″′;

[0054] When the temperature difference ΔT L When the duration difference threshold ΔT″′ is less than the time difference threshold, it means there is no impact;

[0055] When the temperature difference ΔT L When it is ≥ the duration difference threshold ΔT″′, it is considered to be influential;

[0056] When the judgment result is that there is an impact, further judge the temperature difference ΔT L The law of change.

[0057] As a preferred solution of the infrared imaging insulator epoxy resin internal defect detection method of the present invention, when the judgment result of the influencing factor of the same defect diameter at different defect depths is that there is an influence, the depth limit value of the detection at different defect depths is calculated:

[0058]

[0059] Among them, D min The calculation formula of (d) is expressed as:

[0060]

[0061] Combining the two sets of formulas, the completed judgment function is expressed as:

[0062]

[0063] In the formula, d represents the defect depth, D represents the defect diameter, and D min (d) is the minimum detectable diameter at the defect depth d, which is obtained by interpolating D min (d), the defect depth d is located at d i and d i+1 between.

[0064] In a second aspect, an embodiment of the present invention provides an infrared imaging insulator epoxy resin internal defect detection system, which includes a model building module, a data acquisition module, and an information judgment module;

[0065] The model building module is used to build an epoxy resin model according to the information of the epoxy resin;

[0066] The data acquisition module is used to collect information change rules of the epoxy resin model and output it as an imaging timing diagram;

[0067] The information judgment module is used to judge the influencing factors of internal defects and obtain a detection method for the epoxy resin model.

[0068] In a third aspect, an embodiment of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, any step of the above-mentioned infrared imaging insulator epoxy resin internal defect detection method is implemented.

[0069] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned infrared imaging insulator epoxy resin internal defect detection method is implemented.

[0070] The beneficial effects of the present invention are as follows: using infrared imaging to obtain internal defect information of pot-type insulators, adopting a comprehensive brightness difference standard method to quickly and accurately distinguish defects such as bubbles and cracks inside pot-type insulators, and by adopting an array-type bubble defect arrangement and precise model construction, efficient scanning can be achieved during the detection process, especially by constructing multiple groups of models with different defect depths and diameters, the system can quickly determine the influencing factors of different defects, reduce unnecessary multi-wavelength scanning, and thus improve the overall scanning efficiency.

[0071] By utilizing detailed mathematical models, such as the differential equation for heat conduction and the expression for the relationship between heat flux density and temperature gradient, the system can more accurately simulate and analyze the heat conduction process. For different defect depths and diameters, this method provides a method to calculate the depth limit and minimum detectable diameter to ensure the accuracy of imaging information. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0073] Figure 1The figure is a flow chart of the method for detecting internal defects of epoxy resin in insulators using infrared imaging.

[0074] Figure 2 Schematic diagram of heat flow conduction.

[0075] Figure 3 This is the imaging timing diagram of the infrared imaging insulator epoxy resin internal defect detection method.

[0076] Figure 4 Schematic diagram of lateral temperature acquisition for the infrared imaging insulator epoxy resin internal defect detection method.

[0077] Figure 5 Schematic diagram of longitudinal temperature acquisition for the infrared imaging insulator epoxy resin internal defect detection method.

[0078] Figure 6 This is a comparison chart of different excitation times for the infrared imaging method for detecting internal defects in epoxy resin of insulators.

[0079] Figure 7 Schematic diagram of defect detection criteria for the infrared imaging insulator epoxy resin internal defect detection method. DETAILED DESCRIPTION

[0080] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0081] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0082] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0083] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0084] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0085] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication 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.

[0086] Example 1

[0087] First of all, it is important to understand that during the heat transfer process, heat follows the second law of thermodynamics and is transferred from high temperature to low temperature in a unique and continuous path. When passing through defective and non-defective areas, the heat flow carried by each area remains consistent. According to the thermal circuit theory, the heat flow Q through the thermal resistance is:

[0088]

[0089] Where Q is the heat flow, ΔT is the temperature gradient, and R is the thermal resistance;

[0090] The internal heat flow of the epoxy numerical model with bubble defects is as follows Figure 2 As shown, the continuity of heat flow indicates that any heat flow transmitted to the path must be continuous, that is, the heat flow through the same cross section between different materials or different regions at the same time is equal, and the heat flow Q passing through the cross section S at the same time is equal. Assume that the surface temperature of the tested sample is T1, the temperature of the cross section shown in the middle is T2, and the heat flow is mainly transmitted from top to bottom. In the thermal path L1, the thermal resistance of the first layer of epoxy material is R h1 , the thermal resistance of the second epoxy material is R h2 , the total thermal resistance in L1 is R1 = R h1+ R h2In the heat path L2 with bubble defects, the thermal resistance of the first layer of epoxy material is R h1 , the thermal resistance of the second layer of bubble defects is R q , the total thermal resistance in path L2 is R2 = R h1+ R q , because the thermal resistance of air is much greater than that of epoxy material, that is, R q >>R h2 , so R2>>R1, which directly leads to a larger ΔT in the heat path L2 with bubble defects, so the surface temperature of the sample with bubble defects will be higher than the surface temperature of the non-bubble defects.

[0091] Reference Figure 1 and Figure 3-7 , which is the first embodiment of the present invention, provides an infrared imaging insulator epoxy resin internal defect detection method, comprising the following steps:

[0092] S1. construct an epoxy resin model to be tested, heat the epoxy resin model, and obtain an imaging timing diagram.

[0093] When constructing the epoxy resin model, an array-type bubble defect arrangement is adopted, and the specific arrangement is expressed as follows:

[0094] Create X rows of bubble defects, with Y number of bubble defects in each row;

[0095] The spacing between two adjacent rows of bubble defects is set to x, and the spacing between bubble defects in the same row is set to y;

[0096] The diameter D of each row of bubble defects is set to an increasing trend, and the depth H of the bubble defects in the same row is set to an increasing trend;

[0097] Among them, X>3, Y>3;

[0098] In implementation, X=5, Y=5, and the distances between the center of the bubble defect in the first row and the upper boundary, the left boundary and the right boundary are all 20 mm, the distance between adjacent bubble defects is 20 mm, and the interval between adjacent rows of bubble defects is also 20 mm. The bubble defect diameter D is 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm and 1.0 mm from the first row to the fifth row, respectively. For each row of bubbles, the distance from the center to the upper surface, i.e., the defect depth H, is 0.3 mm, 0.7 mm, 1.1 mm, 1.5 mm and 1.9 mm from left to right, respectively. By arranging bubble defects with the same diameter but different defect depths in the transverse direction, it can be used to analyze the influence of different defect depths on the thermal imaging of the epoxy resin surface under the condition of the same bubble size. At the same time, bubble defects with the same defect depths but different diameters are arranged in the longitudinal direction to analyze the influence of different bubble sizes on the thermal imaging of the epoxy resin surface under the condition of the same depth.

[0099] Table 1: Arrangement of defect diameters at different defect depths

[0100]

[0101]

[0102] In Table 1, H is the defect depth and D is the defect diameter;

[0103] Secondly, the material parameters of the epoxy resin model are consistent with the Al2O3 / epoxy material and the material parameters of the real pot-type insulator. The specific material parameters are: density is 2000kg / m 3 , specific heat capacity is 1035 J / kg·℃, thermal conductivity is 1 W / m·℃. The bubble defects in the sample are set to air, and the material properties are set to: density is 1.2 kg / m 3 , specific heat capacity is 1005J / kg·℃, and thermal conductivity is 0.026W / m·℃.

[0104] The step of heating the epoxy resin model comprises:

[0105] Obtaining the number of bubble defects, setting the same number of halogen lamps according to the number of bubble defects, and setting the halogen lamps and the bubble defects of the epoxy resin model in a one-to-one correspondence;

[0106] Set the distance between the halogen lamp and the epoxy resin model;

[0107] Turn on all halogen lamps synchronously and adjust the power of all halogen lamps to the same power;

[0108] An infrared thermal imager is used to capture and record the dynamic evolution of the surface temperature field of the epoxy resin model to obtain an imaging time sequence diagram;

[0109] The brightness of the halogen lamp adopts the comprehensive brightness difference standard method, selects the best infrared wavelength for reflection and transmission, fuses the transmission information with the reflection information, and obtains the characteristic image of the foreign matter of the detected sample. When there are n foreign matters, the calculation formula of the comprehensive brightness difference is expressed as:

[0110]

[0111] Where ΔK(λ) is the comprehensive brightness difference, Δk j (λ) represents the average brightness of the foreign matter, Δk b (λ) represents the average background brightness, j = 1, 2, 3, ..., n;

[0112] When recording the dynamic evolution of the surface temperature field of the epoxy resin model, an interval time K is set, and the epoxy resin model is sampled once every K time length until the set total time length is reached, and multiple imaging time sequence diagrams are obtained;

[0113] For example, to solve the problem of the change of thermal imaging of the epoxy resin model surface with bubble defects over time, an excitation power of 10000W / m 2 , the excitation time is 6 seconds, the acquisition is performed at intervals of 5 seconds, and the total acquisition time is 30 seconds. Through the finite element simulation method, 6 imaging timing diagrams of bubble defects are obtained. These images clearly show the influence of bubble defects on the surface temperature distribution of epoxy resin small boards. Figure 3 As shown, the temperature difference between the defect area and the non-defect area is significant, and the temperature of the bubble defect area is higher than that of the non-defect area.

[0114] When the epoxy resin model is heated, the propagation function of the heat wave in the cutoff is obtained. In the rectangular coordinate system, the heat conduction differential equation along the direction (x, y, z) at time t is expressed as:

[0115]

[0116] Under the condition of unsteady heat conduction, the second type of boundary conditions is given:

[0117]

[0118] Substituting into the relationship expression between heat flux and temperature gradient, we get:

[0119]

[0120] Where p is the material density, c is the specific heat capacity, α is the diffusion coefficient of the material, specifically α=λ / pc, pc is the volume heat capacity, specifically the ability of an object to store heat, and f(x,y,z,t) is the heat source function;

[0121] Among them, the relationship between heat flux and temperature gradient is expressed as:

[0122]

[0123] In the formula, q represents the heat flux density, ▽T represents the temperature gradient, λ represents the thermal conductivity of the material, and the negative sign represents that the direction of heat transfer is opposite to the direction of the temperature gradient. Expressed as the rate of change of temperature in a certain direction.

[0124] S2. Analyze the imaging timing diagram to obtain the influencing factors of the internal defects of the epoxy resin model.

[0125] The influencing factors of the internal defects of the epoxy resin model include influencing factors of the same defect diameter with different defect depths and influencing factors of the same defect depth with different defect diameters;

[0126] The method for determining the influencing factors of the same defect diameter at different defect depths includes:

[0127] Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera;

[0128] Construct multiple groups of epoxy resin judgment models with different defect depths and the same defect diameter, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect depths;

[0129] Calculate the temperature difference ΔT between the defect point and the non-defect point at different defect depths S , set the depth difference threshold ΔT′;

[0130] When the temperature difference ΔT S When the depth difference threshold ΔT′ is less than the depth difference threshold ΔT′, it means there is no effect;

[0131] When the temperature difference ΔT S When it is ≥ the depth difference threshold ΔT′, it is considered to be influential;

[0132] In the judgment, in view of the influence of different defect depths on the surface temperature of the epoxy resin model, the thermal excitation power is set to 10000W / m 2 , the excitation time is 6s, and the surface thermal imaging feature data of the same bubble defect diameter at different defect depths (0.3mm, 0.7mm, 1.1mm, 1.5mm and 1.9mm) at the 12th second are systematically collected. Through this setting of different defect depths, the influence of bubble defects of different depths on the surface temperature of epoxy material defects is systematically studied. The temperature collection of surface thermal imaging is carried out along the preset horizontal line, and the range of thermal imaging temperature collection is determined, allowing the influence of defects of different depths on the surface temperature to be compared on the same horizontal axis. By collecting data along the line area, it is ensured that the surface thermal imaging features of defects of different depths are compared under the same measurement conditions, which can better observe the specific influence of the depth of the bubble defect on the thermal imaging;

[0133] Five methods were tested, namely, the surface thermal imaging characteristics of bubble defects with different diameters (0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm) at different depths were analyzed, such as Figure 4As shown in the figure, when the diameter of the bubble defect is 1.0mm, the surface temperature distribution at different defect depths. In the figure, the x-axis represents the distance Z from the starting position on the left end to the measuring point, and the y-axis represents the surface temperature of the epoxy material. The bubble defects are located at 10mm, 30mm, 50mm, 70mm, and 90mm in the horizontal direction, respectively. The corresponding defect depths H are 0.3mm, 0.7mm, 1.1mm, 1.5mm, and 1.9mm, respectively. The temperature peak corresponds to the defect position. The surface temperature of the bubble defect is significantly higher than the temperature of the surrounding non-defective area. At different defect depths, the surface temperature of the bubble defect reaches 42.69℃, 41.23℃, 40.80℃, 40.64℃, and 40.57℃, respectively. The reference temperature of the non-defective area is 40.55℃. When the defect depth increases, the surface temperature of the bubble defect decreases by 3.4%, 1.0%, 0.5%, and 0.2%, respectively. The temperature difference ΔT between the defect point and the non-defect point at each depth of the bubble defect S They are 2.14℃, 0.68℃, 0.24℃, 0.09℃ and 0.02℃ respectively. The bubble defect has the largest temperature difference with the surrounding non-defective area at the defect depth of 0.3mm, and the smallest temperature difference at the defect depth of 1.9mm. The overall trend is decreasing. The decrease in temperature difference between the defect point and the non-defect point indicates that the influence of the bubble defect on the surface temperature gradually weakens with the increase of depth. After reaching a certain depth, the bubble defect has almost no effect on the surface temperature. Through different situations, the depth difference threshold ΔT′ is set to determine whether there is an impact.

[0134] The method for determining the influencing factors of the same defect depth with different defect diameters includes:

[0135] Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera;

[0136] Construct multiple groups of epoxy resin judgment models with different defect diameters and the same defect depth, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect diameters;

[0137] Calculate the temperature difference ΔT between the defect point and the non-defect point under different defect diameters Z , set the diameter difference threshold ΔT″;

[0138] When the temperature difference ΔT Z When the diameter difference threshold ΔT″ is less than the diameter difference threshold ΔT″, it means there is no impact;

[0139] When the temperature difference ΔT Z When it is ≥ the diameter difference threshold ΔT″, it is considered to be influential;

[0140] In order to study the effect of different bubble defect diameters on the surface temperature of epoxy materials, the thermal excitation power is set to 10000W / m 2The excitation time is 6s, and the surface thermal imaging feature data of the same defect depth under different bubble defect diameters (0.2mm, 0.4mm, 0.6mm, 0.8mm and 1.0mm) are systematically collected at the 12th second. By setting different bubble defect diameters, the influence of bubble defects of different diameters on the surface temperature of epoxy material defects is systematically analyzed. The temperature collection of surface thermal imaging is carried out along the preset horizontal line, which defines the range of thermal imaging temperature collection, allowing the influence of bubble defects of different diameters on the surface temperature to be compared on the same horizontal axis. The horizontal line collection ensures that the surface thermal imaging features of bubble defects of different diameters are compared under the same measurement conditions, so that the specific influence of the diameter of the bubble defect on the thermal imaging can be better observed;

[0141] The surface thermal imaging features of bubble defects with different defect depths (0.3mm, 0.7mm, 1.1mm, 1.5mm, 1.9mm) at different defect depths were collected and analyzed, such as Figure 5 As shown in the figure, the surface temperature distribution of bubble defects with different diameters is shown when the defect depth is 0.3mm. The x-axis represents the distance L from the point at the line to the starting position of the top, and the y-axis represents the surface temperature T of the epoxy material. The bubble defects are located at 10mm, 30mm, 50mm, 70mm, and 90mm in the horizontal direction, respectively. The corresponding bubble defect diameters are 0.2mm, 0.4mm, 0.6mm, 0.8mm, and 1.0mm, respectively. The temperature peak corresponds to the defect position. The surface temperature of the bubble defect is significantly higher than the temperature of the surrounding non-defective area. Under different diameters of bubble defects, the surface temperature of the bubble defect reaches 40.65℃, 40.97℃, 41.41℃, 42.03℃, and 42.69℃, respectively. When the diameter of the bubble defect increases, the surface temperature of the bubble defect increases by 0.7%, 1.1%, 1.5%, and 1.6%, respectively. The temperature difference ΔT between the defect point and the non-defect point of the bubble defect at each diameter Z They are 0.1℃, 0.42℃, 0.86℃, 1.48℃ and 2.14℃ respectively. The bubble defect has a minimum temperature difference with the surrounding non-defective area when its diameter is 0.2mm, and the maximum temperature difference is at a defect diameter of 1.0mm. The overall trend is upward. The increase in temperature difference between the defect point and the non-defect point indicates that the influence of bubble defects on the surface temperature increases with the increase of diameter.

[0142] The influencing factors of the internal defects of the epoxy resin model also include the influence of the duration of the different halogen lamps being turned on;

[0143] The method for determining the influencing factors of the different halogen lamp on-times includes:

[0144] Set the power of the halogen lamp, the capture time of the infrared thermal imager, and the duration of the halogen lamp groups;

[0145] An epoxy resin judgment model is constructed, and the epoxy resin judgment model is heated to obtain a temperature collection graph of different halogen lamp opening times;

[0146] Calculate the temperature difference ΔT between the defective point and the non-defective point under different halogen lamp on-times L , set the duration difference threshold ΔT″′;

[0147] When the temperature difference ΔT L When the duration difference threshold ΔT″′ is less than the time difference threshold, it means there is no impact;

[0148] When the temperature difference ΔT L When it is ≥ the duration difference threshold ΔT″′, it is considered to be influential;

[0149] When the judgment result is that there is an impact, further judge the temperature difference ΔT L The law of change;

[0150] In order to solve the problem of the influence of different halogen lamp on-time (excitation time) on the surface temperature of the defect, this paper collected the bubble defect temperature diagram at the 6th second of the defect diameter of 1.0 mm and the defect depth of 0.3 mm under three excitation times, namely Figure 6 As shown in the figure, as the excitation time increases, the peak value of the surface temperature at the defect increases, the temperature reference value at the non-defect increases, the temperature difference between the defect and the non-defect increases, and the temperature difference ΔT L The increase from 0.09℃ to 1.65℃, the increase in excitation time leads to an increase in diffusion distance and an increase in the blurring of defect boundaries. The affected area of ​​the surface temperature increases from 2.95mm 2 Increased to 19.16mm 2 , the affected area increases significantly, and too large an affected surface area is not conducive to the identification of the defect size. Therefore, in this embodiment, 6s is selected as the lamp on time (excitation time).

[0151] S3. Determine the influencing factors of internal defects and determine the detection method of the epoxy resin model based on the judgment results.

[0152] When the influencing factors of the same defect diameter at different defect depths are judged to be influential, the depth limit values ​​of detection at different defect depths are calculated:

[0153]

[0154] Among them, D min The calculation formula of (d) is expressed as:

[0155]

[0156] Combining the two sets of formulas, the completed judgment function is expressed as:

[0157]

[0158] In the formula, d represents the defect depth, D represents the defect diameter, and D min (d) is the minimum detectable diameter at the defect depth d, which is obtained by interpolating D min (d), the defect depth d is located at d i and d i+1 between;

[0159] like Figure 7 As shown, the surface temperature changes of the defect point and the non-defect point are recorded. The temperature peak at the defect point is 23.68°C, the background temperature of the non-defect point is 23.47°C, and the temperature difference between the defect point and the non-defect point is calculated to be 0.21°C. In this embodiment, the infrared thermal imager can distinguish images with a temperature difference greater than or equal to 0.05°C, that is, when there is a bubble defect, the temperature difference between the defect point and the non-defect point is ≥0.05°C, and it is considered that the bubble defect can be detected.

[0160] In summary, infrared imaging is used to obtain the internal defect information of pot-type insulators, and the comprehensive brightness difference standard method is adopted to quickly and accurately distinguish defects such as bubbles and cracks inside pot-type insulators. By adopting array-type bubble defect layout and precise model construction, efficient scanning can be achieved during the detection process. In particular, by constructing multiple groups of models with different defect depths and diameters, the system can quickly determine the influencing factors of different defects and reduce unnecessary multi-wavelength scanning, thereby improving the overall scanning efficiency.

[0161] By utilizing detailed mathematical models, such as the differential equation for heat conduction and the expression for the relationship between heat flux density and temperature gradient, the system can more accurately simulate and analyze the heat conduction process. For different defect depths and diameters, this method provides a method to calculate the depth limit and minimum detectable diameter to ensure the accuracy of imaging information.

[0162] Example 2

[0163] On the basis of the first embodiment, this embodiment further provides an infrared imaging insulator epoxy resin internal defect detection system, including a model building module, a data acquisition module, and an information judgment module;

[0164] The model building module is used to build an epoxy resin model according to the information of the epoxy resin;

[0165] The data acquisition module is used to collect information change rules of the epoxy resin model and output it as an imaging timing diagram;

[0166] The information judgment module is used to judge the influencing factors of internal defects and obtain a detection method for the epoxy resin model.

[0167] This embodiment also provides a computer device, which is suitable for the infrared imaging insulator epoxy resin internal defect detection method, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the infrared imaging insulator epoxy resin internal defect detection method proposed in the above embodiment.

[0168] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0169] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the infrared imaging insulator epoxy resin internal defect detection method proposed in the above embodiment is implemented.

[0170] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0171] Example 3

[0172] On the basis of the previous two embodiments, this embodiment provides an infrared imaging insulator epoxy resin internal defect detection method. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0173] Existing method: Use the existing multi-wavelength infrared imaging method to detect defects of different depths and diameters respectively, fuse the results of imaging at different wavelengths, analyze the imaging images and calculate the recognition rate, missed detection rate, and accuracy of imaging information.

[0174] Table 2: Comparison of Example 1 with the existing method

[0175]

[0176]

[0177] It can be seen from Table 2 that Example 1 is superior to the existing multi-wavelength infrared imaging technology in multiple key indicators. These comparative data show that the new method not only improves the detection efficiency and accuracy, but also significantly reduces the missed detection rate and improves the accuracy of imaging information, showing good application potential.

[0178] Example 1 simplifies the imaging process and reduces time expenditure through single wavelength excitation. The total detection time is only 90 seconds, which is about 40% faster than the existing method; the defect recognition rate is improved to 92.3%, showing higher accuracy. This improvement is due to the fact that Example 1 more effectively utilizes the infrared characteristics under single wavelength excitation and more clearly captures the thermal characteristics of the defects; the missed detection rate is reduced to 2.5%, which significantly reduces the risk of omissions in detection. Example 1 reduces information loss in the complex wavelength fusion process and improves the reliability of detection; the recognition rate of foreign objects with the same reflective characteristics is 91.8%, indicating that Example 1 has better differentiation ability when dealing with foreign objects with similar reflective characteristics, effectively reducing missed detections.

[0179] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An infrared imaging insulator epoxy resin internal defect detection method, characterized in that: The following steps are included: constructing an epoxy resin model to be tested, heating the epoxy resin model, and obtaining an imaging timing diagram; Analyze the imaging timing diagram to obtain the influencing factors of the internal defects of the epoxy resin model; The influencing factors of internal defects are judged, and the detection method of the epoxy resin model is determined based on the judgment results.

2. The infrared imaging insulator epoxy resin internal defect detection method according to claim 1, characterized in that: When constructing the epoxy resin model, an array-type bubble defect arrangement is adopted, and the specific arrangement is expressed as follows: Create X rows of bubble defects, with Y number of bubble defects in each row; The spacing between two adjacent rows of bubble defects is set to x, and the spacing between bubble defects in the same row is set to y; The diameter D of each row of bubble defects is set to an increasing trend, and the depth H of the bubble defects in the same row is set to an increasing trend; Among them, X>3, Y>3.

3. The infrared imaging insulator epoxy resin internal defect detection method according to claim 2, characterized in that: The step of heating the epoxy resin model comprises: Obtaining the number of bubble defects, setting the same number of halogen lamps according to the number of bubble defects, and setting the halogen lamps and the bubble defects of the epoxy resin model in a one-to-one correspondence; Set the distance between the halogen lamp and the epoxy resin model; Turn on all halogen lamps synchronously and adjust the power of all halogen lamps to the same power; An infrared thermal imager is used to capture and record the dynamic evolution of the surface temperature field of the epoxy resin model to obtain an imaging time sequence diagram; When recording the dynamic evolution of the surface temperature field of the epoxy resin model, an interval time K is set, and the epoxy resin model is sampled once every K time length until the set total time length is reached, and multiple imaging time sequence diagrams are obtained; The brightness of the halogen lamp adopts the comprehensive brightness difference standard method, selects the best infrared wavelength for reflection and transmission, fuses the transmission information with the reflection information, and obtains the characteristic image of the foreign matter of the detected sample. When there are n foreign matters, the calculation formula of the comprehensive brightness difference is expressed as: Where ΔK(λ) is the comprehensive brightness difference, Δk j (λ) represents the average brightness of the foreign matter, Δk b (λ) represents the average background brightness, j=1, 2, 3, ..., n.

4. The infrared imaging insulator epoxy resin internal defect detection method according to claim 3, characterized in that: When the epoxy resin model is heated, the propagation function of the heat wave in the cutoff is obtained. In the rectangular coordinate system, the heat conduction differential equation along the direction (x, y, z) at time t is expressed as: Under the condition of unsteady heat conduction, the second type of boundary conditions is given: Substituting into the relationship expression between heat flux and temperature gradient, we get: Where p is the material density, c is the specific heat capacity, α is the diffusion coefficient of the material, specifically α=λ / pc, pc is the volume heat capacity, specifically the ability of an object to store heat, and f(x,y,z,t) is the heat source function; Among them, the relationship between heat flux and temperature gradient is expressed as: In the formula, q represents the heat flux density, ▽T represents the temperature gradient, λ represents the thermal conductivity of the material, and the negative sign represents that the direction of heat transfer is opposite to the direction of the temperature gradient. Expressed as the rate of change of temperature in a certain direction.

5. The infrared imaging insulator epoxy resin internal defect detection method according to claim 4, characterized in that: The influencing factors of the internal defects of the epoxy resin model include influencing factors of the same defect diameter with different defect depths and influencing factors of the same defect depth with different defect diameters; The method for determining the influencing factors of the same defect diameter at different defect depths includes: Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera; Construct multiple groups of epoxy resin judgment models with different defect depths and the same defect diameter, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect depths; Calculate the temperature difference ΔT between the defect point and the non-defect point at different defect depths S , set the depth difference threshold ΔT′; When the temperature difference ΔT S When the depth difference threshold ΔT′ is less than the depth difference threshold ΔT′, it means there is no effect; When the temperature difference ΔT S When it is ≥ the depth difference threshold ΔT′, it is considered to be influential; The method for determining the influencing factors of the same defect depth with different defect diameters includes: Set the power level and on-time of the halogen lamp, as well as the capture time of the infrared camera; Construct multiple groups of epoxy resin judgment models with different defect diameters and the same defect depth, and heat the epoxy resin judgment models to obtain temperature acquisition diagrams with different defect diameters; Calculate the temperature difference ΔT between the defect point and the non-defect point under different defect diameters Z , set the diameter difference threshold ΔT″; When the temperature difference ΔT Z When the diameter difference threshold ΔT″ is less than the diameter difference threshold ΔT″, it means there is no impact; When the temperature difference ΔT Z When the diameter difference threshold ΔT″ is greater than or equal to the diameter difference threshold ΔT″, it indicates that there is an impact.

6. The infrared imaging insulator epoxy resin internal defect detection method according to claim 5, characterized in that: The influencing factors of the internal defects of the epoxy resin model also include the influencing factors of the duration of the halogen lamp being turned on; The method for determining the influencing factors of the different halogen lamp on-times includes: Set the power of the halogen lamp, the capture time of the infrared thermal imager, and the duration of the halogen lamp groups; An epoxy resin judgment model is constructed, and the epoxy resin judgment model is heated to obtain a temperature collection graph of different halogen lamp opening times; Calculate the temperature difference ΔT between the defective point and the non-defective point under different halogen lamp on-times L , set the duration difference threshold ΔT″′; When the temperature difference ΔT L When the duration difference threshold ΔT″′ is less than the time difference threshold, it means there is no impact; When the temperature difference ΔT L When it is ≥ the duration difference threshold ΔT″′, it is considered to be influential; When the judgment result is that there is an impact, further judge the temperature difference ΔT L The law of change.

7. The infrared imaging insulator epoxy resin internal defect detection method according to claim 6, characterized in that: When the influencing factors of the same defect diameter at different defect depths are judged to be influential, the depth limit values ​​of detection at different defect depths are calculated: Among them, D min The calculation formula of (d) is expressed as: Combining the two sets of formulas, the completed judgment function is expressed as: In the formula, d represents the defect depth, D represents the defect diameter, and D min (d) is the minimum detectable diameter at the defect depth d, which is obtained by interpolating D min (d), the defect depth d is located at d i and d i+1 between.

8. An infrared imaging insulator epoxy resin internal defect detection system, based on the infrared imaging insulator epoxy resin internal defect detection method according to any one of claims 1 to 7, characterized in that: It includes a model building module, a data acquisition module, and an information judgment module; The model building module is used to build an epoxy resin model according to the information of the epoxy resin; The data acquisition module is used to collect information change rules of the epoxy resin model and output it as an imaging timing diagram; The information judgment module is used to judge the influencing factors of internal defects and obtain a detection method for the epoxy resin model.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the infrared imaging insulator epoxy resin internal defect detection method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the infrared imaging insulator epoxy resin internal defect detection method according to any one of claims 1 to 7 are implemented.

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