Method and device for releasing residual stress of epoxy composite insulator

Abstract

The method comprises the following steps: preparing an epoxy sample with a bidirectional strain gauge, carrying out multi-stage thermal cycle treatment on the epoxy sample, and recording strain data to determine an optimal treatment parameter combination, namely temperature, heat preservation time, cooling rate and cycle index; carrying out stress reduction treatment on the epoxy composite insulator based on the optimal treatment parameter combination; the device comprises a programmable oven, a strain gauge and an upper computer. The method is easy and convenient to operate and low in cost, through multi-scale collaborative optimization, the residual stress of the current commercial epoxy composite insulating part can be remarkably reduced, the reliability of the epoxy composite insulating part for the ultra / extra-high voltage power equipment is remarkably improved, and the method has wide engineering application prospects.

Description

Technical Field

[0001] The present invention relates to the field of power transmission and transformation insulation equipment production, and more particularly to a residual stress release method and device for epoxy composite insulation parts. Background Art

[0002] In power systems, GIL / GIS equipment is widely used due to its compact structure and high reliability. Epoxy resin insulation, a key component, performs both electrical insulation and mechanical support. However, with increasing voltage levels and larger equipment, the size of epoxy insulation components continues to increase, leading to an increasing problem of residual stress within them.

[0003] At present, epoxy composite insulation parts are mainly made of epoxy resin and inorganic fillers such as alumina, which are cast according to a certain doping ratio. The insulation parts inevitably contain residual stress before they are put into operation, which is mainly due to the casting and curing process during the manufacturing process. In the existing technology, residual stress is easily caused during the production process of epoxy composite insulation parts due to uneven heat dissipation or unreasonable temperature control. During long-term operation, epoxy composite insulation parts continue to face complex working conditions such as strong electric fields, high air pressure, mechanical stress and uneven temperature distribution. The existence of residual stress under complex conditions significantly increases the risk of insulation breakdown and mechanical failure, resulting in frequent explosion and breakdown failures, which seriously threaten the safe and stable operation of the power system. At present, manufacturers have not yet implemented relevant factory inspection standards, which greatly restricts the operational reliability of epoxy composite insulation parts.

[0004] Therefore, in the face of the current situation that residual stress exists after the epoxy composite insulation parts are cast, there is an urgent need for a method to effectively reduce the residual stress, improve the preparation level of high-voltage electrical equipment, thereby reducing the accident rate of epoxy composite insulation parts and improving the reliability of power system operation. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology and solve the problems of reduced performance and increased breakdown risk of insulating parts caused by residual stress in the existing technology, the present invention proposes a residual stress release method and device for epoxy composite insulating parts. Through multi-scale collaborative optimization and combined with thermal aging treatment process, small-size specimens are used to simulate large-size insulating parts, establish a "unit-whole" stress transfer relationship, and determine the optimal combination of four-dimensional parameters including temperature, time, rate, and number. Finally, the process is applied to the actual insulating part processing, which can significantly reduce the residual stress of epoxy composite insulating parts and improve their mechanical strength and electrical insulation performance.

[0006] The purpose of the present invention can be achieved through the following technical solutions.

[0007] A method for relieving residual stress of an epoxy composite insulation component comprises the following steps:

[0008] S1 prepares epoxy specimens with biaxial strain gauges;

[0009] S2 performs multi-stage thermal cycling on epoxy samples. Each cycle includes heating, constant temperature, and cooling stages. The strain data of the biaxial strain gauges in each cycle is monitored and recorded in real time. The optimal treatment parameter combination for reducing the residual stress of the epoxy composite material is determined based on the strain data of the biaxial strain gauges in each cycle.

[0010] S3 uses the optimal treatment parameter combination and performs stress reduction treatment on the epoxy composite insulation component according to the same multi-stage thermal cycle treatment process as step S2; wherein the epoxy composite insulation component and the epoxy sample are made of epoxy composite materials with the same mass ratio.

[0011] Furthermore, the preparation process of the epoxy sample described in step S1 is as follows: the epoxy composite material for preparing the epoxy composite insulating part is mixed in a specific proportion, heated to a molten state, poured into a mold after vacuum degassing, and solidified and demolded to obtain the epoxy sample corresponding to the epoxy composite insulating part; wherein, a bidirectional strain gauge is suspended at the center position of the mold.

[0012] Furthermore, the specific preparation process of the epoxy sample in step S1 is as follows:

[0013] S1.1 Pour the molten epoxy composite material into the mold with the biaxial strain gauge and start curing;

[0014] The epoxy composite material for preparing the epoxy composite insulation is mixed in a specific ratio, heated to a molten state, and vacuum degassed. A bidirectional strain gauge is simultaneously hung at the center of the mold. The mold is placed in a programmable oven. After the mold with the bidirectional strain gauge is preheated, the molten epoxy composite material after vacuum degassed is poured into the mold. The leads of the bidirectional strain gauge are connected to the strain gauge. The values ​​measured by the strain gauge are transmitted to a host computer. The programmable oven door is closed, and curing begins.

[0015] S1.2 Reset and record the biaxial strain gauge values ​​during the curing process. Stop recording after the curing is complete and the temperature drops to room temperature. Remove the epoxy sample from the mold.

[0016] After setting the curing program in programmable oven 1, the strain gauge value is cleared and reset on the host computer, and the value of the bidirectional strain gauge changing with time during the curing process is recorded until the curing is completed and the temperature drops to room temperature, and the collection is stopped. The epoxy sample is demolded and removed from the mold. After demolding, the epoxy sample is free of fixed constraints, which can eliminate the interference of fixed constraints on the collected values ​​of the bidirectional strain gauge.

[0017] Furthermore, the bidirectional strain gauge in step S1 is composed of two strain gauges, and the two strain gauges are perpendicular to each other and have equal lengths.

[0018] Furthermore, the multi-stage thermal cycle treatment in step S2 includes:

[0019] Heating stage: heating the epoxy sample from room temperature to the set temperature T at a constant rate;

[0020] Constant temperature stage: the epoxy sample after heating treatment is kept at the set temperature T for a certain set time t;

[0021] Cooling stage: The epoxy sample after constant temperature treatment is cooled to room temperature at the set cooling rate v;

[0022] After completing one cycle of the above-mentioned heating, constant temperature and cooling stages, the cycle is repeated n times.

[0023] Furthermore, in step S2, the epoxy sample is subjected to a multi-stage thermal cycle treatment, wherein one cycle includes a heating, a constant temperature, and a cooling stage. The strain data of the biaxial strain gauge in each cycle is monitored and recorded in real time. The optimal treatment parameter combination for reducing the residual stress of the epoxy composite material is determined based on the strain data of the biaxial strain gauge in each cycle. The specific process is as follows:

[0024] S2.1 Reset the biaxial strain gauge at room temperature and start recording the values. Heat the epoxy specimen to the set temperature T using a programmable oven.

[0025] S2.2 After the epoxy sample is heated to the set temperature T, it is kept at a constant temperature for the set holding time t;

[0026] S2.3 After the constant temperature treatment, the epoxy sample is cooled to room temperature at the set cooling rate v;

[0027] S2.4 After the epoxy sample cools to room temperature, the programmable oven stops working, the bidirectional strain gauge stops recording the value, and the heating process is completed once;

[0028] S2.5 calculates the strain difference of the bidirectional strain gauge in this heating process and determines whether the strain difference reaches the strain tolerance range; if so, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to this cycle are used as the optimal processing parameter combination; if not, adjust the temperature T, holding time t, cooling rate v, and number of cycles n, and repeat the above steps S2.1 to S2.5; in addition, if the number of heating process cycles n so far reaches the set maximum value but the strain difference still does not meet the strain tolerance range requirements, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to the minimum strain difference are taken as the optimal processing parameter combination.

[0029] Furthermore, the epoxy composite insulating component is an insulator for power equipment, including but not limited to a three-post insulator, a pot-type insulator or a barrel-type insulator.

[0030] The purpose of the present invention can also be achieved through the following technical solutions.

[0031] A residual stress release device for epoxy composite insulation components comprises a programmable oven, a strain gauge, and a host computer. The programmable oven is used to set an adjustment temperature T, a holding time t, a cooling rate v, and a number of cycles n, and to perform multi-stage thermal cycling treatment on an epoxy specimen with a built-in bidirectional strain gauge according to the above-set parameters. The strain gauge is connected to the leads of the bidirectional strain gauge and is used to upload the values ​​measured in each stage to the host computer in real time. The host computer is used to record the strain values ​​of the bidirectional strain gauge over time in real time in each stage, and determine the optimal treatment parameter combination based on the strain data of the bidirectional strain gauge in each heating process cycle.

[0032] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0033] (1) The present invention uses the same epoxy composite material as the epoxy composite insulation part to mix in a specific proportion to prepare an epoxy composite material specimen, and embeds a bidirectional strain gauge during the curing process to monitor the transverse and longitudinal strain changes in real time. Through strain data recording and analysis, the optimal processing parameter combination for reducing the residual stress of the epoxy composite material is determined, namely, temperature (T), holding time (t), cooling rate (v) and number of cycles (n).

[0034] (2) The present invention performs a multi-cycle thermal aging treatment on the cured epoxy sample, including three stages: heating, heat preservation and cooling. By adjusting the temperature (T), heat preservation time (t), cooling rate (v) and number of cycles (n), the optimal process parameters are explored. The difference of the bidirectional strain gauge is ≤1% as the criterion for negligible residual stress. At this time, the strain is mainly caused by thermal expansion and contraction, and the contribution of stress is lower than the engineering error range. The process economy and stress relief effect are balanced, and the maximum number of cycles is set. During the treatment process, the epoxy composite insulation part remains in a free state to avoid the introduction of additional stress by mechanical constraints, ensuring consistency with the experimental conditions of the epoxy sample.

[0035] (3) The present invention directly applies the optimized thermal aging treatment process to actual epoxy composite insulation components (such as three-pillar insulators) to effectively reduce residual stress. Experimental results show that this method can reduce the maximum residual stress by about 50%, and the stress distribution is more uniform, significantly improving the long-term operating reliability of insulation components.

[0036] (4) The residual stress release method for epoxy composite insulation components proposed in the present invention is highly scientific. It uses bidirectional strain gauges to monitor stress changes in real time and combines this with quantitative analysis based on generalized Hooke's law to ensure accurate optimization of process parameters. It is widely applicable to epoxy composite insulation components of various shapes and sizes, and is particularly suitable for key insulation components of ultra-high / ultra-high voltage power equipment. The process is simple, the cost is controllable, and it can be easily promoted and applied in existing production lines, resulting in significant economic and social benefits. The present invention provides an efficient and reliable solution for residual stress control in epoxy composite insulation components, which is of great significance for improving the operational safety of power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the residual stress release method of the epoxy composite insulation part of the present invention;

[0038] Figure 2 Schematic diagram of a residual stress release device for an epoxy composite insulation member of the present invention;

[0039] Figure 3 is the strain value of the biaxial strain gauge of the epoxy sample of the present invention at different cycle times;

[0040] Figure 4 This is a comparison diagram of the front residual stress of the epoxy composite insulation component before and after treatment according to the present invention;

[0041] Figure 5 This is a comparison diagram of the residual stress on the back side of the epoxy composite insulation component before and after treatment according to the present invention.

[0042] Reference numerals: 1-programmable oven; 2-epoxy sample; 3-bidirectional strain gauge;

[0043] 4-strain gauge; 5-host computer; 6-epoxy composite insulation. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings.

[0045] The present invention proposes a method for relieving residual stress in epoxy composite insulation components. First, an epoxy sample 2 with a bidirectional strain gauge 3 is prepared. Because the epoxy sample 2 is smaller than an epoxy composite insulation component 6 made of the same material, the unconstrained epoxy sample 2 can be considered as a constituent unit of the epoxy composite insulation component 6. The epoxy sample 2 is subjected to a multi-stage thermal cycle treatment, and the optimal parameter combination for reducing the residual stress of the epoxy composite material is analyzed and obtained. Finally, the unconstrained epoxy composite insulation component 6 is treated to achieve the purpose of reducing the residual stress of the epoxy composite insulation component 6. The specific implementation process is as follows:

[0046] S1: Preparation of epoxy specimens with biaxial strain gauges.

[0047] The epoxy composite material for preparing the epoxy composite insulation part is mixed in a specific ratio, heated to a molten state, vacuum degassed, poured into a mold, cured and demolded to obtain the epoxy sample corresponding to the epoxy composite insulation part; wherein a bidirectional strain gauge is suspended at the center of the mold. Specifically, the following steps are included:

[0048] S1.1 Pour the molten epoxy composite material into the mold with the biaxial strain gauge and start curing.

[0049] In this step, the epoxy composite material used to make the epoxy composite insulation is mixed in a specific ratio, heated to a molten state, and then vacuum degassed. For example, epoxy composites used in engineering applications are generally made from epoxy resin / alumina. In this example, the epoxy composite material is a mixture of epoxy resin (CT-5531), alumina (particle size 10 microns), and a curing agent (HY-5533-1) in a mass ratio of 100:320:38. The composite material is heated to 130°C until it is molten, thoroughly stirred, and then vacuum degassed.

[0050] In this step, a bidirectional strain gauge 3 is suspended in the center of the mold. The bidirectional strain gauge consists of two perpendicular strain gauges of equal length. The strain gauge parallel to the mold bottom surface is oriented horizontally, while the strain gauge perpendicular to the mold bottom surface is oriented vertically. The sensitive grid of the bidirectional strain gauge 3 (one sensitive grid corresponds to two leads) can be 2 mm long. For example, the mold is a cylindrical vessel with a diameter of 2.5 cm and a height of 3 cm.

[0051] In this step, before curing, to maintain the same curing temperature as the mold with biaxial strain gauge 3 and the epoxy composite material, the mold is placed in a programmable oven 1 (temperature control accuracy can be ±1°C). The mold with biaxial strain gauge is preheated to 130°C. The degassed molten epoxy composite material is then poured into the mold. The leads of biaxial strain gauge 3 are connected to strain gauge 4. The values ​​measured by strain gauge 4 are transmitted in real time to the host computer 5. The door of programmable oven 1 is closed, and curing begins. For example, the curing temperature is set to 130°C (130°C throughout the curing process) and the curing time is set to 10.5 hours.

[0052] S1.2 Reset and record the biaxial strain gauge values ​​during the curing process. Stop recording after curing is complete and the temperature drops to room temperature. Remove the epoxy specimen from the mold.

[0053] In this step, after the curing program is set through the programmable oven 1, the strain gauge value is cleared and reset on the host computer 5, and the strain value of the bidirectional strain gauge 3 that changes with time during the curing process (i.e., real-time monitoring of the transverse and longitudinal strain changes) is collected and recorded. The recording sampling frequency can be set to collect once every 1 minute until the curing is completed and the temperature drops to room temperature, and the collection is stopped. The epoxy sample 2 is demolded and removed from the mold. After demolding, the epoxy sample 2 is free of fixed constraints, and the interference of fixed constraints on the collected values ​​of the bidirectional strain gauge 3 can be eliminated.

[0054] S2: Perform multi-stage thermal cycle treatment on epoxy samples. Each cycle includes three stages: heating, constant temperature, and cooling. The strain data of the biaxial strain gauge in each cycle is monitored and recorded in real time. The optimal treatment parameter combination for reducing the residual stress of the epoxy composite material is determined based on the strain data of the biaxial strain gauge in each cycle. Specific process:

[0055] S2.1 Heating stage: Reset the bidirectional strain gauge 3 at room temperature and start recording the value. Heat the epoxy specimen from room temperature to the set temperature T at a constant rate.

[0056] In this step, the epoxy sample 2 is placed in a programmable oven 1 at room temperature, the bidirectional strain gauge 3 and the strain meter 4 are connected, and the strain meter 4 is connected to the host computer 5. The strain gauge value is cleared and reset on the host computer 5, and the temperature T is set in the programmable oven 1. The time required to heat from room temperature to temperature T can be set to 30 minutes. For example, if the glass transition temperature of the epoxy composite material used in the present invention is 117°C, then the heating temperature T can be set to 55°C (low temperature range), 85°C (medium and low temperature range), 115°C (close to the glass transition temperature), 145°C (higher than the glass transition temperature), or 175°C (high temperature range), etc., covering the actual operating temperature range and heat treatment sensitive range of the epoxy composite insulation.

[0057] S2.2 Constant temperature stage: After the epoxy sample is heated to the set temperature T, it is kept at a constant temperature for the set holding time t.

[0058] In this step, after setting the heating temperature T, the holding time t of the heating temperature is set in the programmable oven 1, and the epoxy sample 2 is maintained at the temperature T for the holding time t. More specifically, combined with the time and economic requirements in actual engineering applications, for example, the holding time t is 4h or 8h, etc., taking into account both engineering efficiency and stress relaxation sufficiency.

[0059] S2.3 Cooling stage: After the constant temperature treatment is completed, the epoxy sample is cooled to room temperature at the set cooling rate v.

[0060] In this step, after setting the holding time t, the cooling rate v of the epoxy sample 2 after holding is set in the programmable oven 1, and the epoxy sample is cooled to room temperature at the set cooling rate v. More specifically, based on the actual project, the cooling rate v is set to 10°C / h or 3°C / h, etc.

[0061] S2.4 After the epoxy sample cools to room temperature, the programmable oven stops working, the bidirectional strain gauge 3 stops recording the value, and the heating process is completed once.

[0062] In this step, the trigger condition for programmable oven 1 to stop operation is set to be the cooling of epoxy sample 2 to room temperature. After programmable oven 1 stops heating, host computer 5 stops recording and deriving the value of bidirectional strain gauge 3. A heating process cycle consists of steps S2.1 to S2.4.

[0063] S2.5 calculates the strain difference of the bidirectional strain gauge in this heating process and determines whether the strain difference reaches the strain tolerance range; if so, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to this cycle are used as the optimal processing parameter combination; if not, adjust the temperature T, holding time t, cooling rate v, and number of cycles n, and repeat the above steps S2.1 to S2.5; in addition, if the number of heating process cycles n so far reaches the set maximum value but the strain difference still does not meet the strain tolerance range requirements, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to the minimum strain difference are taken as the optimal processing parameter combination.

[0064] In this step, the strain difference of the bidirectional strain gauge 3 in each cycle is calculated, that is, the strain data difference between the transverse strain gauge and the longitudinal strain gauge in the same heating process cycle. Based on the strain difference, it is judged whether the parameters (T, t, v, n) have reached the optimal solution. According to the generalized Hooke's law, for linear elastic and isotropic materials, the relationship between stress (σ) and strain (∈) is:

[0065]

[0066] Where E is the elastic modulus, v is Poisson's ratio, ∈ 11 ,∈ 22 ,∈ 11 are the strains in the three orthogonal directions in the stress field, σ 11 , σ 22 , σ 33are the stresses in three orthogonal directions in the stress field respectively. If the strain in a certain direction is constrained, that is, when the epoxy sample 2 or the epoxy composite insulation 6 is constrained, stress will be generated in this direction through the Poisson effect (even if it is not directly loaded). For the epoxy sample 2 after demolding, the direction of the bidirectional strain gauge 3 can be regarded as orthogonal and vertical in any direction. Therefore, when the strain difference of the unconstrained epoxy sample 2 reaches the tolerance range, it means that the contribution of stress to strain is small, and the strain mainly comes from the thermal expansion and contraction of the epoxy composite material. More specifically, for example, the strain tolerance is set to 1%. In addition, combined with the actual requirements of time and economy for the project, it is necessary to set the maximum number of heating process cycles, for example, the maximum number of cycles is set to 6 times. If the strain difference is ≤1%, it is determined that the optimal treatment effect has been achieved, and the T, t, v, and n corresponding to this cycle are used as the optimal treatment parameter combination. If the number of heating process cycles n has reached the set maximum value but the strain difference still does not meet the strain tolerance range requirements, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to the minimum strain difference are used as the optimal treatment parameter combination. Figure 3 This is the difference in the bidirectional strain gauge 3 of the epoxy sample 2 under different numbers of cycles of the embodiment of the present invention. It can be seen that compared with the second cycle, the difference in the bidirectional strain gauge is smaller in the third cycle, especially the strain curves in the latter part are almost overlapping, indicating that the strain is mainly caused by the thermal expansion and contraction of the epoxy sample 2, while the residual stress is small. At this time, the number of cycles can be further increased, and the combination of T, t, and v can be adjusted until the strain curve difference at any stage in the heating process reaches the tolerance range.

[0067] In the above step S2, the epoxy sample 2 after curing is subjected to a cycle of heating, constant temperature, and cooling again, and the optimal solution for reducing residual stress in the composite material used in the epoxy sample 2 is obtained. More specifically, since the epoxy sample 2 and the epoxy composite insulating part 6 are not fixedly constrained, and the volume of the epoxy sample 2 is relatively small, the epoxy sample 2 can be regarded as a constituent unit of the epoxy composite insulating part 6. The epoxy sample 2 and the epoxy composite insulating part 6 use the same material system and remain in an unconstrained state during processing to ensure the consistency of the strain-stress relationship and establish a "unit-to-whole" stress transfer relationship. When the epoxy composite insulating part 6 is consistent with the composite material used in the epoxy sample 2, the strain parameter change law measured by the bidirectional strain gauge 3 in the epoxy sample 2 is applicable to the epoxy composite insulating part 6.

[0068] S3: Using the optimal treatment parameter combination, the epoxy composite insulation component 6 is subjected to stress reduction treatment according to the same multi-stage thermal cycle treatment process as step S2.

[0069] In this step, the epoxy composite insulator 6 and the epoxy sample 2 are made of epoxy composite materials of the same mass ratio. The epoxy composite insulator 6 is an insulator for power equipment, including but not limited to insulators of any shape, such as three-post insulators, basin insulators, or table insulators, and is suitable for GIS / GIL insulation equipment. After the epoxy composite insulator 6 is cured, it is cyclically treated according to steps S2.1 to S2.4 using an optimized temperature T, holding time t, cooling rate v, and number of cycles n to achieve stress reduction.

[0070] For example: Figure 2 The epoxy composite insulation member 6 shown is a three-pillar insulator. The epoxy composite insulation member 6 is placed in a programmable oven 1. The determined optimal treatment parameter combination (i.e., the optimized temperature T, holding time t, cooling rate v, and number of cycles n) is input into the programmable oven 1. The epoxy composite insulation member 6 is cyclically treated according to steps S2.1 to S2.4. More specifically, in this example, the optimal treatment parameter combination is T = 145°C, t = 8h, v = 3°C / h, and n = 6. The results before and after treatment are shown in FIG. Figure 4 and Figure 5 As shown in the figure, the stress distribution and stress value of the front and back sides (the front and back sides are relative and no special distinction is made) of the three-pillar insulator before and after treatment show that the maximum residual stress is reduced by about 50%, and the residual stress distribution after treatment is more uniform, indicating that the method provided by the present invention has a better effect on reducing the residual stress of epoxy composite insulation parts.

[0071] Based on the principle of the residual stress release method of the epoxy composite insulation component, the present invention also proposes a residual stress release device for the epoxy composite insulation component, such as Figure 2 As shown, the system primarily comprises a programmable oven 1, a strain gauge 4, and a host computer 5. The programmable oven 1 is used to set and adjust the temperature T, holding time t, cooling rate v, and number of cycles n, and to perform multi-stage thermal cycling on an epoxy specimen 2 equipped with a built-in biaxial strain gauge according to these parameters. The strain gauge 4 is connected to the leads of the biaxial strain gauge 3 and is used to upload the measured values ​​at each stage to the host computer 5 in real time. The host computer 5 is used to record the strain values ​​of the biaxial strain gauge over time during each stage in real time and determine the optimal combination of processing parameters based on the strain data of the biaxial strain gauge during each heating process cycle.

[0072] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific functions and working processes. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which are all protected by the present invention.

Claims

1. A method for releasing residual stress of an epoxy composite insulation component, characterized in that: The following steps are involved: S1 prepares epoxy specimens with biaxial strain gauges; S2 performs multi-stage thermal cycling on epoxy samples. Each cycle includes heating, constant temperature, and cooling stages. The strain data of the biaxial strain gauges in each cycle is monitored and recorded in real time. The optimal treatment parameter combination for reducing the residual stress of the epoxy composite material is determined based on the strain data of the biaxial strain gauges in each cycle. S3 uses the optimal treatment parameter combination and performs stress reduction treatment on the epoxy composite insulation component according to the same multi-stage thermal cycle treatment process as step S2; wherein the epoxy composite insulation component and the epoxy sample are made of epoxy composite materials with the same mass ratio.

2. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: The preparation process of the epoxy sample described in step S1 is as follows: the epoxy composite material for preparing the epoxy composite insulating part is mixed in a specific proportion, heated to a molten state, poured into a mold after vacuum degassing, and solidified and demolded to obtain the epoxy sample corresponding to the epoxy composite insulating part; wherein, a bidirectional strain gauge is suspended at the center position of the mold.

3. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: The specific preparation process of the epoxy sample in step S1 is as follows: S1.1 Pour the molten epoxy composite material into the mold with the biaxial strain gauge and start curing; The epoxy composite material for preparing the epoxy composite insulation is mixed in a specific ratio, heated to a molten state, and vacuum degassed. A bidirectional strain gauge is simultaneously hung at the center of the mold. The mold is placed in a programmable oven. After the mold with the bidirectional strain gauge is preheated, the molten epoxy composite material after vacuum degassed is poured into the mold. The leads of the bidirectional strain gauge are connected to the strain gauge. The values ​​measured by the strain gauge are transmitted to a host computer. The programmable oven door is closed, and curing begins. S1.2 Reset and record the biaxial strain gauge values ​​during the curing process. Stop recording after the curing is complete and the temperature drops to room temperature. Remove the epoxy sample from the mold. After setting the curing program in the programmable oven, the strain gauge value is cleared and reset on the host computer at the same time, and the value of the bidirectional strain gauge changing with time during the curing process is recorded until the curing is completed and the temperature drops to room temperature, and the collection is stopped. The epoxy sample is demolded and removed from the mold. After demolding, the epoxy sample is free of fixed constraints, which can eliminate the interference of fixed constraints on the collected values ​​of the bidirectional strain gauge.

4. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: The bidirectional strain gauge in step S1 is composed of two strain gauges, which are perpendicular to each other and have equal lengths.

5. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: The multi-stage thermal cycle treatment in step S2 includes: Heating stage: heating the epoxy sample from room temperature to the set temperature T at a constant rate; Constant temperature stage: the epoxy sample after heating treatment is kept at the set temperature T for a certain set time t; Cooling stage: The epoxy sample after constant temperature treatment is cooled to room temperature at the set cooling rate v; After completing one cycle of the above-mentioned heating, constant temperature and cooling stages, the cycle is repeated n times.

6. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: In step S2, the epoxy sample is subjected to a multi-stage thermal cycle treatment. Each cycle includes a heating, constant temperature, and cooling stage. The strain data of the biaxial strain gauge in each cycle is monitored and recorded in real time. The optimal treatment parameter combination for reducing the residual stress of the epoxy composite material is determined based on the strain data of the biaxial strain gauge in each cycle. The specific process is as follows: S2.1 Reset the biaxial strain gauge at room temperature and start recording the values. Heat the epoxy specimen to the set temperature T using a programmable oven. S2.2 After the epoxy sample is heated to the set temperature T, it is kept at a constant temperature for the set holding time t; S2.3 After the constant temperature treatment, the epoxy sample is cooled to room temperature at the set cooling rate v; S2.4 After the epoxy sample cools to room temperature, the programmable oven stops working, the bidirectional strain gauge stops recording the value, and the heating process is completed once; S2.5 calculates the strain difference of the bidirectional strain gauge in this heating process and determines whether the strain difference reaches the strain tolerance range; if so, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to this cycle are used as the optimal processing parameter combination; if not, adjust the temperature T, holding time t, cooling rate v, and number of cycles n, and repeat the above steps S2.1 to S2.5; in addition, if the number of heating process cycles n so far reaches the set maximum value but the strain difference still does not meet the strain tolerance range requirements, the temperature T, holding time t, cooling rate v, and number of cycles n corresponding to the minimum strain difference are taken as the optimal processing parameter combination.

7. The residual stress release method of the epoxy composite insulation according to claim 1, characterized in that: The epoxy composite insulating component is an insulator for power equipment, including but not limited to a three-post insulator, a basin insulator or a table insulator.

8. A device for releasing residual stress of an epoxy composite insulating component based on the residual stress releasing method of an epoxy composite insulating component according to any one of claims 1 to 7, characterized in that: The invention comprises a programmable oven, a strain gauge, and a host computer; the programmable oven is used to set and adjust the temperature T, the holding time t, the cooling rate v, and the number of cycles n, and to perform multi-stage thermal cycle treatment on the epoxy specimen with the built-in bidirectional strain gauge according to the above-set parameters; the strain gauge is connected to the lead of the bidirectional strain gauge and is used to upload the values ​​measured in each stage to the host computer in real time; the host computer is used to record the strain value of the bidirectional strain gauge changing with time in real time in each stage, and determine the optimal processing parameter combination based on the strain data of the bidirectional strain gauge in each heating process cycle.

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