Wall bushing and assembling method thereof

Abstract

The invention discloses a wall bushing and an assembling method of the wall bushing, the wall bushing comprises a hollow insulator, a central guide rod and a driving member, and the hollow insulator is arranged to be a hollow structure with two closed ends along the axial direction; the central guide rod penetrates through the hollow insulator; the driving part is used for stretching the center guide rod in the axial direction. According to the application, the central guide rod is stretched in advance through the driving piece, so that the actual elongation of the central guide rod caused by external reasons in the actual use process can be counteracted with the pre-stretched elongation, and the risk of insulation failure of the wall bushing caused by violent stretching deformation of the central guide rod in the use process is reduced; and the product reliability of the wall bushing can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of power transmission and transformation insulation equipment, and in particular to a wall bushing and an assembling method of the wall bushing. Background Art

[0002] In the prior art, under the action of ultra-large current, the center guide rod of the ultra-high voltage DC wall bushing stretches violently, causing huge axial pressure to accumulate inside the center guide rod, thereby causing the center guide rod to sag and deform. The sagging deformation will cause the internal electric field strength of the wall bushing to change, which can easily lead to insulation failure of the wall bushing and low product reliability. Summary of the invention

[0003] The main technical problem solved by the present application is to provide a wall bushing and an assembly method of the wall bushing, which can solve the problem of insulation failure of the wall bushing, thereby improving the product reliability of the wall bushing.

[0004] In order to solve the above technical problems, the present application adopts a technical solution: providing a wall bushing, the wall bushing includes a hollow insulator, the center guide rod and the driving member, the hollow insulator is axially arranged as a hollow structure with two ends closed; the center guide rod is penetrated by the hollow insulator; the driving member is used to stretch the center guide rod in the axial direction.

[0005] The above scheme stretches the center guide rod in advance through the driving member so that the actual elongation of the center guide rod caused by external reasons during actual use can offset the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing due to severe tensile deformation of the center guide rod during use, and can improve the product reliability of the wall bushing.

[0006] Wherein, the center guide rod includes a first end and a second end spaced apart in the axial direction, and the hollow insulator includes: a hollow insulating tube, the center guide rod is inserted into the hollow insulating tube; a first flange, fixedly connected to the first end and fixedly connected to one end of the hollow insulating tube; a second flange, detachably mounted on the second end and fixedly connected to the other end of the hollow insulating tube; wherein the driving member includes a threaded knob, the threaded knob is detachably mounted on the second end and is located on the side of the second flange away from the first flange.

[0007] In the above scheme, the hollow insulating tube allows the central guide rod to pass through it without electrical contact, and the first flange and the second flange can ensure a tight fit between the central guide rod and the hollow insulating tube and prevent external factors such as water vapor from invading the hollow insulating tube.

[0008] Wherein, the second end portion is provided with a scale mark for displaying the elongation of the central guide rod.

[0009] The above solution can provide an intuitive way to measure and display the elongation of the central guide rod relative to the hollow insulator by setting the scale.

[0010] Among them, a through hole is provided on the second flange for penetrating the second end; a first chamfer is provided on the inner side of an end of the through hole away from the first flange, and a second chamfer is provided on the outer side of an end of the threaded knob close to the second flange, the first chamfer and the second chamfer are arranged correspondingly, and a polytetrafluoroethylene layer is provided on the first chamfer.

[0011] The above scheme can reduce the friction of the threaded knob when it is assembled on the second end of the center guide rod by setting the first chamfer and the second chamfer, which can significantly reduce the difficulty of inserting the center guide rod into the through hole and installing the threaded knob, and at the same time avoid damage to the center guide rod by the sharp edges of the inner side of the through hole and the threaded knob.

[0012] To solve the above technical problems, the present application also provides a technical solution: providing an assembly method for a wall bushing, the method comprising: inserting a center guide rod through a hollow insulator which is axially arranged as a hollow structure with both ends closed; and stretching the center guide rod using a driving member.

[0013] The above scheme stretches the center guide rod in advance through the driving member so that the actual elongation of the center guide rod caused by external reasons during actual use is offset by the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing due to severe tensile deformation of the center guide rod during use.

[0014] Wherein, the step of stretching the central guide rod by using a driving member includes: stretching the central guide rod so that the elongation of the central guide rod is equal to the product of the length of the central guide rod and the pre-compensation coefficient.

[0015] The above scheme introduces a pre-compensation coefficient to ensure that under actual working conditions, even if thermal expansion and contraction within the expected range occur, the center guide rod can still be maintained within the ideal length range, thereby ensuring the stability and safety of the wall bushing and improving the product reliability of the wall bushing.

[0016] Wherein, before stretching the center guide rod, it also includes: determining the pre-compensation coefficient according to target parameters, wherein the target parameters include at least one of temperature compensation strain, relaxation compensation, and creep compensation; wherein the temperature compensation strain characterizes the temperature elongation of the center guide rod from the assembly temperature during assembly to the highest operating temperature during use; the relaxation compensation characterizes the plastic deformation of the center guide rod after relaxation occurs; and the creep compensation characterizes the plastic deformation of the center guide rod after creep occurs.

[0017] The above scheme can pre-adjust the length of the center guide rod by determining the pre-compensation coefficient to offset the deformation of the center guide rod caused by factors such as temperature change, relaxation and creep during subsequent actual use.

[0018] Wherein, the step of determining the pre-compensation coefficient according to the target parameter includes: calculating the sum of the temperature compensation strain, the relaxation compensation amount, and the creep compensation amount to obtain the pre-compensation coefficient.

[0019] The above scheme determines the pre-compensation coefficient according to the target parameter, so that the pre-compensation coefficient can be effectively determined and applied, thereby ensuring the performance stability and reliability of the center guide rod in actual use.

[0020] Wherein, before calculating the sum of the temperature compensation strain, the relaxation compensation and the creep compensation to obtain the pre-compensation coefficient, it also includes: judging whether the center guide rod meets the target conditions, wherein the target conditions include that the axial stress to which the center guide rod is subjected during use is less than a first preset axial stress, and the ambient temperature is less than a first preset temperature; if not, executing the step of calculating the sum of the temperature compensation strain, the relaxation compensation and the creep compensation to obtain the pre-compensation coefficient; if satisfied, calculating the sum of the temperature compensation strain and the relaxation compensation to obtain the pre-compensation coefficient.

[0021] The above scheme determines whether the central guide rod meets the target conditions and then determines whether it is necessary to calculate the creep compensation amount, thereby improving the accuracy of the obtained pre-compensation coefficient.

[0022] The target parameter includes the temperature compensation strain, wherein the temperature compensation strain is calculated according to the following formula: ε1 = a(T MAX +100-T0); where ε1 is the temperature compensation strain, a is the linear expansion coefficient of the material used for the central guide rod, T MAX is the maximum ambient temperature of the center guide rod during use, and T0 is the assembly temperature of the center guide rod.

[0023] In the above scheme, suitable materials and a reasonable structure can be selected for the center guide rod through the calculation formula of the temperature compensation strain, thereby minimizing the adverse effects of temperature changes.

[0024] Among them, the target parameters include the relaxation compensation amount, and the relaxation compensation amount is calculated according to the following formula: ε2=[1 / (1-P)-1]ε1; wherein ε2 is the relaxation compensation amount, and P is the relaxation rate of the material used for the center guide rod.

[0025] In the above scheme, suitable materials and a reasonable structure can be selected for the center guide rod through the calculation formula of the relaxation compensation strain, thereby minimizing the adverse effects caused by relaxation changes.

[0026] The target parameter includes the creep compensation amount, wherein the creep compensation amount is calculated according to the following formula: ε3 = Aσ 5.65 T 0.47 ; Wherein, ε3 is the creep compensation amount, A is the material constant of the center guide rod, σ is the creep stress applied to the center guide rod, and T is the creep time of the center guide rod.

[0027] In the above scheme, suitable materials and a reasonable structure can be selected for the center guide rod through the calculation formula of the creep compensation strain, thereby minimizing the adverse effects caused by creep changes.

[0028] Wherein, the center guide rod includes a first end and a second end spaced apart in the axial direction, the hollow insulator includes a hollow insulating tube, a first flange and a second flange, the first flange is fixedly connected to the first end, the driving member includes a threaded knob, and the step of using the driving member to stretch the center guide rod includes: connecting the first end to the hollow insulating tube through the first flange; sleeve the second flange on the second end, and make the second flange connected to the hollow insulating tube; sleeve the threaded knob on the second end, rotate the threaded knob, and continue to rotate the threaded knob after the threaded knob abuts against the second flange, thereby stretching the center guide rod.

[0029] In the above scheme, the central guide rod can be stretched or compressed axially by rotating the threaded knob, thereby adjusting the position of the central guide rod relative to the hollow insulator to achieve stretching.

[0030] Beneficial effect: The present application pre-stretches the center guide rod through a driving member so that the actual elongation of the center guide rod due to external reasons during actual use can offset the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing due to severe tensile deformation of the center guide rod during use, and can improve the product reliability of the wall bushing.

[0031] At the same time, the present application can provide an intuitive way to measure and display the elongation of the central guide rod relative to the hollow insulator by setting a ruler scale.

[0032] In addition, providing the first chamfer and the second chamfer on the second flange can reduce the friction when the threaded knob is assembled on the second end of the center guide rod, which can significantly reduce the difficulty of inserting the center guide rod into the through hole and installing the threaded knob, while also preventing the sharp edges of the inner side of the through hole and the threaded knob from damaging the center guide rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0034] Figure 1 A schematic diagram of a partial structure of a wall bushing provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of the structure of the central guide rod before pre-stretching provided in one embodiment of the present application;

[0036] Figure 3 A flowchart of a method for assembling a wall sleeve according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] The terms "first", "second", "third" in this application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", "third" can expressly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of this application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the steps or units listed, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] Please also read Figure 1 and Figure 2 In one embodiment of the present application, a wall bushing 100 is provided, and the wall bushing 100 includes a hollow insulator 10, a central guide rod 20, and a drive member 30. The wall bushing 100 is a commonly used device in the power industry, and is mainly used to safely guide conductive components from one environment to another environment, such as from indoors to outdoors or from outdoors to indoors. The central guide rod 20 plays a conductive role in the wall bushing 100 to ensure the normal transmission of electric energy. The drive member 30 serves as a power source to adjust the stretching amount of the central guide rod 20.

[0041] Specifically, the hollow insulator 10 is axially configured as a hollow structure with both ends closed. The hollow insulator 10 is designed as a hollow structure with both ends closed, which helps to isolate the current between different electrical locations, provides good insulation protection for the wall bushing 100, and also provides good mechanical support for the wall bushing 100.

[0042] The central guide rod 20 is passed through the hollow insulator 10 , so that one end of the hollow insulator 10 can be connected to a device that needs to transmit power, and the other end of the hollow insulator 10 can be connected to a ground point or other circuit parts.

[0043] The driving member 30 is used to stretch the central guide rod 20 in the axial direction. The main function of the driving member 30 is to adjust the stretching amount of the central guide rod 20 in the axial direction. Specifically, the stretching action can be achieved by manual operation or an electric mechanism.

[0044] In the above-mentioned wall bushing 100, the center guide rod 20 is pre-stretched by the driving member 30 so that the actual elongation of the center guide rod 20 due to external reasons during actual use can offset the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing 100 due to severe tensile deformation of the center guide rod 20 during use, and can improve the product reliability of the wall bushing 100.

[0045] Please continue reading Figure 1 and Figure 2 In one embodiment, the central guide rod 20 includes a first end 21 and a second end 22 spaced apart in the axial direction, and the hollow insulator 10 includes a hollow insulating tube 11, a first flange 12, and a second flange 13. The central guide rod 20 is inserted into the hollow insulating tube 11, and the first flange 12 is fixedly connected to the first end 21 and fixedly connected to one end of the hollow insulating tube 11. The second flange 13 is detachably mounted on the second end 22 and fixedly connected to the other end of the hollow insulating tube 11. The driving member 30 includes a threaded knob 31, which is detachably mounted on the second end 22 and is located on the side of the second flange 13 away from the first flange 12.

[0046] In the above arrangement, the hollow insulating tube 11 allows the central guide rod 20 to pass through it without electrical contact, and the first flange 12 and the second flange 13 can ensure a tight fit between the central guide rod 20 and the hollow insulating tube 11, and prevent external factors such as water vapor from invading the hollow insulating tube 11. In addition, the first flange 12 and the second flange 13 also facilitate operators to install the entire wall bushing 100 on a wall or other structure. At the same time, the threaded knob 31 can achieve axial tension or compression of the central guide rod 20 by rotation, thereby adjusting the position of the central guide rod 20 relative to the hollow insulator 10.

[0047] In one embodiment, the hollow insulating tube 11 is generally made of a material that is resistant to high temperature, corrosion and has high dielectric strength, such as ceramic or composite materials. For example, the hollow insulating tube 11 can be a hollow tube formed by pultrusion of glass fiber or aramid fiber impregnated with epoxy resin, which is not limited in the present application.

[0048] In one embodiment, the driving member 30 also includes a locking portion (not shown), which cooperates with the threaded knob 31 so that after the threaded knob 31 drives the second end 22 to stretch a preset distance, the position of the threaded knob 31 can remain stable, thereby reducing the risk of accidental loosening of the threaded knob 31 resulting in unstable stretching of the second end 22 of the center guide rod 20.

[0049] Please continue reading Figure 1 and Figure 2 In one embodiment, the second end portion 22 is provided with a scale 221 for displaying the elongation of the central guide rod 20. The main function of the scale 221 is to provide an intuitive way to measure and display the elongation of the central guide rod 20 relative to the hollow insulator 10.

[0050] In one embodiment, the ruler scale 221 may be in metric units (eg, millimeters, centimeters) or imperial units (eg, inches), which is not limited herein.

[0051] In one embodiment, in order to facilitate reading of the value, the scale scale 221 of the second end portion 22 may be provided with a contrasting color or a fluorescent mark so that the specific scale value can be identified even in low light conditions. In addition, a large number or other obvious mark may be provided at a key position of the scale scale 221 (e.g., a preset stretching amount) to help with quick positioning.

[0052] In other embodiments, the second end 22 of the center guide rod 20 can be directly set with a stretching termination point, that is, when the second end 22 passes through the second flange 13 and the driving member 30 drives the second end 22 to stretch, when the stretching termination point just exposes the side of the second flange 13 away from the first flange 12, the driving member 30 stops stretching the second end of the center guide rod 20, thereby improving the convenience and efficiency of the stretching process.

[0053] Please continue reading Figure 1 and Figure 2 In one embodiment, a through hole 131 is provided on the second flange 13 for passing the second end 22. A first chamfer is provided on the inner side of the end of the through hole 131 away from the first flange 12, and a second chamfer is provided on the outer side of the end of the threaded knob 31 close to the second flange 13. The first chamfer and the second chamfer are provided correspondingly, and a polytetrafluoroethylene layer (PTFE) is provided on the first chamfer. Among them, the position, size and shape of the through hole 131 on the second flange 13 must match the center guide rod 20 to improve the good fit between the center guide rod 20 and the second flange 13. The first chamfer and the second chamfer can reduce the friction force of the threaded knob 31 when it is assembled on the second end 22 of the center guide rod 20, which can significantly reduce the difficulty of inserting the center guide rod 20 into the through hole 131 and installing the threaded knob 31, and at the same time, it can also prevent the sharp edges of the inner side of the through hole 131 and the threaded knob 31 from damaging the center guide rod 20.

[0054] The polytetrafluoroethylene layer is provided on the first chamfer, which can further reduce the wear of components caused by the friction between the center guide rod 20 and the second flange 13, and improve the service life of the second flange 13 and the center guide rod 20. At the same time, the polytetrafluoroethylene layer also has good chemical stability and self-lubricating properties, and is suitable for electrical equipment that needs to operate reliably for a long time.

[0055] Please also read Figure 1 , Figure 2 and Figure 3 The present application also provides an assembly method of a wall bushing 100, the method comprising:

[0056] S200: The central guide rod 20 is inserted into the hollow insulator 10 which is a hollow structure with closed ends in the axial direction.

[0057] During the installation process, the first end portion 21 of the central guide rod 20 is aligned with an opening at one end of the hollow insulator 10 and slowly inserted into the hollow insulator 10 until the central guide rod 20 is completely disposed in the hollow insulator 10 .

[0058] Specifically, the central guide rod 20 includes a first end portion 21 and a second end portion 22 spaced apart in the axial direction, and the hollow insulator 10 includes a hollow insulating tube 11, a first flange 12, and a second flange 13. During installation, the first end portion 21 can be connected to the hollow insulating tube 11 through the first flange 12, and then the second flange 13 can be sleeved on the second end portion 22, and the second flange 13 can be connected to the hollow insulating tube 11, so that the central guide rod 20 is arranged in the hollow insulator 10.

[0059] S210 : Utilizing the driving member 30 to stretch the central guide rod 20 .

[0060] Specifically, the central guide rod 20 is stretched by the driving member 30 so that the end of the central guide rod 20 can be stretched in the axial direction relative to the hollow insulator 10, thereby realizing the pre-stretching action of the central guide rod 20. The driving member 30 includes a threaded knob 31, and the threaded knob 31 can realize the axial stretching or compression of the central guide rod 20 by rotating, thereby adjusting the position of the central guide rod 20 relative to the hollow insulator 10.

[0061] In the above method, the center guide rod 20 is pre-stretched by the driving member 30 so that the actual elongation of the center guide rod 20 due to external reasons during actual use is offset by the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing 100 due to severe tensile deformation of the center guide rod 20 during use, and improving the product reliability of the wall bushing 100.

[0062] Please continue reading Figure 1 , Figure 2and Figure 3 In one embodiment, step S210 includes:

[0063] S211: stretching the central guide rod 20 so that the elongation of the central guide rod 20 is equal to the product of the length of the central guide rod 20 and the pre-compensation coefficient.

[0064] That is, the elongation amount=the original length of the center guide rod 20*the pre-compensation coefficient.

[0065] Assuming that the original length of the central guide rod 20 is L (unit: meter) and the pre-compensation coefficient is C (unitless), the length L' of the central guide rod 20 after extension can be calculated by the following formula:

[0066] L′=L+(L*C);

[0067] For example, if L=1 meter and C=0.05 (ie, 5% pre-compensation), the elongation is 1*0.05=0.05 meter, and the final length of the central guide rod 20 is L′=1+0.05=1.05 meter.

[0068] Specifically, the pre-compensation coefficient C is a preset value, which mainly considers the change in the length of the central guide rod 20 caused by temperature change, material creep or other environmental factors. By introducing the pre-compensation coefficient C, it can be ensured that the central guide rod 20 can still be kept within the ideal length range under actual working conditions even if thermal expansion and contraction within the expected range occur, thereby ensuring the stability and safety of the wall bushing 100 and improving the product reliability of the wall bushing 100.

[0069] In one embodiment, before step S211, the method further includes:

[0070] S212: Determine a pre-compensation coefficient C according to the target parameter.

[0071] The target parameter includes at least one of a temperature compensation strain amount ε1, a relaxation compensation amount ε2, and a creep compensation amount ε3.

[0072] The temperature compensation strain ε1 represents the temperature elongation of the center guide rod 20 from the assembly temperature during assembly to the maximum operating temperature during use. The relaxation compensation ε2 represents the plastic deformation of the center guide rod 20 after relaxation occurs. The creep compensation ε3 represents the plastic deformation of the center guide rod 20 after creep occurs.

[0073] Specifically, by determining the pre-compensation coefficient C, the length of the central guide rod 20 can be pre-adjusted to offset the subsequent deformation of the central guide rod 20 caused by factors such as temperature change, relaxation and creep during actual use.

[0074] In one embodiment, the temperature compensation strain ε1 refers to the linear elongation or shortening of the central guide rod 20 when the temperature changes. By pre-compensating the elongation caused by the temperature change, the internal stress of the central guide rod 20 caused by the temperature change can be reduced, thereby extending the service life of the central guide rod 20.

[0075] In one embodiment, the temperature compensation strain ε1 is calculated according to the following formula:

[0076] ε1=a(T MAX +100-T0);

[0077] Where ε1 is the temperature compensation strain, a is the linear expansion coefficient of the material used for the center guide rod 20, T MAX is the maximum ambient temperature of the central guide rod 20 during use, T0 is the assembly temperature of the central guide rod 20, and the existing technical specifications stipulate that the maximum operating temperature of the central guide rod 20 is T MAX +100.

[0078] The calculation formula of the temperature compensation strain ε1 can be used to select suitable materials and design a reasonable structure for the center guide rod 20, thereby minimizing the adverse effects of temperature changes.

[0079] In one embodiment, if the central guide rod 20 is made of aluminum alloy, the linear expansion coefficient a of the aluminum alloy is 2.2×10 -5 / K. It can be understood that when the central guide rod 20 is made of other materials, the linear expansion coefficient a can be set to other values, which is not limited here.

[0080] In one embodiment, relaxation refers to the plastic deformation of a material after being subjected to stress for a long time, and the material cannot completely return to its original state even after the external force is removed. By pre-applying a relaxation compensation amount ε2 to the central guide rod 20, the internal tension of the central guide rod 20 can be maintained during its use, reducing the risk of performance degradation of the central guide rod 20 due to relaxation, thereby improving the reliability and safety of the wall bushing 100.

[0081] In one embodiment, the relaxation compensation amount ε2 is calculated according to the following formula:

[0082] ε2=[1 / (1-P)-1]ε1;

[0083] Wherein, ε2 is the relaxation compensation amount, and P is the relaxation rate of the material used for the center guide rod 20.

[0084] In one embodiment, if the central guide rod 20 is made of aluminum alloy, the relaxation rate P of the aluminum alloy is 5%, then ε2 = [1 / (1-5%)-1]ε1≈0.05ε1. It can be understood that when the central guide rod 20 is made of other materials, the relaxation rate P can be set to other values, which is not limited here.

[0085] In one embodiment, creep refers to the plastic deformation of a material that gradually occurs over time under constant stress. The creep compensation amount ε3 can ensure the dimensional stability of the center guide rod 20 during long-term use, reducing the risk of failure of the center guide rod 20 due to creep. At the same time, applying the creep compensation amount ε3 to the center guide rod 20 in advance can also reduce the fatigue damage of the center guide rod 20 caused by creep, thereby improving the durability and service life of the center guide rod 20.

[0086] In one embodiment, the creep compensation amount ε3 is calculated according to the following formula:

[0087] ε3=Aσ 5.65 T 0.47 ;

[0088] Among them, ε3 is the creep compensation amount, A is the material constant of the center guide rod 20, σ is the creep stress on the center guide rod 20, and T is the creep time of the center guide rod 20, with h as the unit.

[0089] In one embodiment, if the central guide rod 20 is made of aluminum alloy, the material constant A of the aluminum alloy is 9.49*10 -18 It can be understood that when the central guide rod 20 is made of other materials, the calculation formula of the creep compensation amount ε3 can be adjusted accordingly, and no limitation is made here.

[0090] In one embodiment, step S212 includes:

[0091] S2121: Calculate the sum of the temperature compensation strain ε1, the relaxation compensation ε2, and the creep compensation ε3 to obtain the pre-compensation coefficient C.

[0092] The pre-compensation coefficient C is a comprehensive result based on the temperature compensation strain ε1, the relaxation compensation ε2, and the creep compensation ε3. The pre-compensation coefficient C is determined according to the target parameters so that the pre-compensation coefficient C can be effectively determined and applied, thereby ensuring the performance stability and reliability of the center guide rod 20 in actual use. During the assembly process, the original length L of the center guide rod 20 is adjusted according to the pre-compensation coefficient C, thereby offsetting the deformation of the center guide rod 20 that may occur in the future.

[0093] In one embodiment, before step S2121, the method further includes:

[0094] S2122: Determine whether the central guide rod 20 meets the target conditions, wherein the target conditions include that the axial stress to which the central guide rod 20 is subjected during use is less than a first preset axial stress and the ambient temperature is less than a first preset temperature.

[0095] If not satisfied, execute the above step S2121; otherwise, execute step S2123.

[0096] S2123: Calculate the sum of the temperature compensation strain ε1 and the relaxation compensation ε2 to obtain the pre-compensation coefficient C.

[0097] Generally, creep and stress relaxation are essentially the same, but stress relaxation emphasizes creep at room temperature, while the creep of the central guide rod 20 of the present application considers creep caused by high temperature, so the creep compensation ε3 can be ignored. Creep is a long-term effect and is highly correlated with axial stress and temperature.

[0098] In one embodiment, the first preset axial stress is set to 100MPa, and the first preset temperature is set to 145°C. The center guide rod 20 made of aluminum alloy will not experience destructive creep and continuous stable creep when the ambient temperature is below 145°C. Therefore, when the axial stress to which the center guide rod 20 is subjected for a long time during use is less than 100Mpa and the ambient temperature of the center guide rod 20 is lower than 145°C for a long time, the creep ε3 of the center guide rod 20 caused by the axial stress can be ignored. At this time, the pre-compensation coefficient C only needs to calculate the sum of the temperature compensation strain ε1 and the relaxation compensation ε2.

[0099] It can be understood that the values ​​of the first preset axial stress and the first preset temperature can be set according to the material of the central guide rod 20, and are not limited here.

[0100] In one embodiment, after step S212 and before step S211 , step S220 and step S230 are further included.

[0101] S220: Verify the axial stress applied to the center guide rod 20 during the pre-stretching process.

[0102] In order to achieve the stretching of the central guide rod 20, an axial stress needs to be applied to the central guide rod 20. This axial stress should not exceed the nominal yield strength f of the material of the central guide rod 20 at room temperature. 0.2 At this time, the stress-strain curve corresponding to the pre-compensation coefficient C is still in the linear elastic stage, and the corresponding axial stress σ1=E*C, where E is the elastic modulus of the material of the center guide rod 20.

[0103] Therefore, it is necessary to verify that σ1 <f 0.2If the above conditions cannot be met, it means that the implemented axial stress σ1 will directly damage the material during the pre-stretching process, so the center guide rod 20 needs to be replaced with a higher strength material for preparation.

[0104] Furthermore, after the central guide rod 20 is put into operation, its temperature is usually high due to power-on, and its high-temperature residual stress σ2 should not exceed the residual nominal yield strength of the central guide rod 20 material under high temperature in the operating environment. High temperature residual stress T MAX is the maximum ambient temperature of the center guide rod 20 during use, is the residual elastic modulus of the center guide rod 20 after being exposed to the highest operating temperature, and T0 is the assembly temperature of the center guide rod 20.

[0105] Therefore, it is necessary to verify that If the above conditions cannot be met, it indicates that the implemented axial stress σ1 will cause the central guide rod 20 to be damaged after it is powered on and put into operation, so the central guide rod 20 needs to be replaced with a material with higher strength for preparation.

[0106] Furthermore, during the maintenance process of the central guide rod 20, its low-temperature stress should not exceed the low-temperature nominal yield strength of the central guide rod 20 material under the low temperature of the maintenance environment. T MIN is the lowest temperature of the center guide rod 20 during the overhaul period, is the low temperature elastic modulus of the central guide rod 20 after exposure to the lowest temperature, and T0 is the assembly temperature of the central guide rod 20.

[0107] Therefore, it is necessary to verify that If the above conditions cannot be met, it indicates that the implemented axial stress σ1 will cause the central guide rod 20 to be damaged at the lowest temperature of power failure, so the central guide rod 20 needs to be replaced with a higher strength material for preparation.

[0108] It should be noted that the specific parameters required for the above verification can be obtained through existing technical specifications and will not be repeated here.

[0109] S230: Perform fatigue calculation on the central guide rod 20.

[0110] Among them, fatigue verification of the center guide rod 20 involves two aspects. On the one hand, it is to verify whether the stress cycle of the center guide rod 20 caused by the change of ambient temperature during operation meets the standard. On the other hand, it is to verify whether the stress cycle of the center guide rod 20 caused by maintenance meets the standard.

[0111] Specifically, the local maximum daily temperature difference ΔT d Estimate the corresponding fatigue stress amplitude, that is, the stress amplitude of the central guide rod 20 caused by the change in ambient temperature Stress amplitude caused by maintenance Then, it is sufficient to determine whether the corresponding stress cycle satisfies the SN curve corresponding to the material of the central guide rod 20 according to the existing technical specifications.

[0112] It is understandable that, for the center guide rod 20 made of other materials, its fatigue life needs to be evaluated according to the SN curve corresponding to the material, which will not be elaborated here.

[0113] In one embodiment, the specific process of the assembly method of the wall sleeve 100 includes the following:

[0114] First, the first end portion 21 is connected to the hollow insulating tube 11 through the first flange 12 .

[0115] Specifically, the first end 21 of the center guide rod 20 is fixedly connected to the first flange 12, and then the first flange 12 is fastened to the hollow insulating tube 11 using an appropriate fixing method. During the connection process, a level or other alignment tools can be used to ensure that the first flange 12 and the hollow insulating tube 11 are aligned in the correct axial direction.

[0116] Next, the second flange 13 is sleeved on the second end portion 22 , and the second flange 13 is connected to the hollow insulating tube 11 .

[0117] Finally, the threaded knob 31 is sleeved on the second end portion 22 , and the threaded knob 31 is rotated. After the threaded knob 31 abuts against the second flange 13 , the threaded knob 31 is further rotated, thereby stretching the central guide rod 20 .

[0118] Specifically, the operator can slowly rotate the threaded knob 31 to gradually increase the preload. During the stretching process, a strain gauge or a displacement sensor or other equipment can be used to monitor the stretching of the second end 22 of the central guide rod 20 to ensure that the desired stretching amount is achieved. When the desired stretching amount is achieved, the threaded knob 31 is completely tightened, and all connection positions are checked to see if they are firm and reliable.

[0119] In the above-mentioned assembly method, the center guide rod 20 is pre-stretched by the driving member 30 so that the actual elongation of the center guide rod 20 due to external reasons during actual use is offset by the pre-stretching elongation, thereby reducing the risk of insulation failure of the wall bushing 100 due to severe tensile deformation of the center guide rod 20 during use, thereby improving the product reliability of the wall bushing 100.

[0120] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A wall bushing, characterized in that: The wall bushing comprises: Hollow insulators are arranged axially as hollow structures with both ends closed; A central guide rod, passing through the hollow insulator; A driving member is used for stretching the central guide rod in the axial direction.

2. The wall bushing according to claim 1, characterized in that: The central guide rod comprises a first end and a second end spaced apart in the axial direction, and the hollow insulator comprises: A hollow insulating tube, wherein the central guide rod is passed through the hollow insulating tube; A first flange, fixedly connected to the first end portion and fixedly connected to one end of the hollow insulating tube; A second flange is detachably mounted on the second end portion and is fixedly connected to the other end of the hollow insulating tube; Wherein, the driving member comprises a threaded knob, and the threaded knob is detachably sleeved on the second end portion and is located on a side of the second flange facing away from the first flange.

3. The wall bushing according to claim 2, characterized in that: The second end portion is provided with a scale mark for displaying the elongation of the central guide rod.

4. The wall bushing according to claim 2, characterized in that: A through hole is provided on the second flange for passing the second end portion; a first chamfer is provided on the inner side of an end of the through hole away from the first flange, and a second chamfer is provided on the outer side of an end of the threaded knob close to the second flange, the first chamfer and the second chamfer are arranged correspondingly, and a polytetrafluoroethylene layer is provided on the first chamfer.

5. A method for assembling a wall bushing, characterized in that: The method comprises: The central guide rod is inserted into a hollow insulator which is a hollow structure with closed ends in the axial direction; The central guide rod is stretched using a drive member.

6. The method according to claim 5, characterized in that The step of using a driving member to stretch the central guide rod comprises: The central guide rod is stretched so that the elongation of the central guide rod is equal to the product of the length of the central guide rod and the pre-compensation coefficient.

7. The method according to claim 6, characterized in that Before stretching the central guide rod, the method further comprises: Determining the pre-compensation coefficient according to a target parameter, wherein the target parameter includes at least one of a temperature compensation strain amount, a relaxation compensation amount, and a creep compensation amount; Among them, the temperature compensation strain amount represents the temperature elongation of the center guide rod from the assembly temperature during assembly to the maximum operating temperature during use; the relaxation compensation amount represents the plastic deformation of the center guide rod after relaxation occurs; and the creep compensation amount represents the plastic deformation of the center guide rod after creep occurs.

8. The method according to claim 7, characterized in that The step of determining the pre-compensation coefficient according to the target parameter comprises: The sum of the temperature compensation strain, the relaxation compensation amount, and the creep compensation amount is calculated to obtain the pre-compensation coefficient.

9. The method according to claim 8, characterized in that Before calculating the sum of the temperature compensation strain, the relaxation compensation amount, and the creep compensation amount to obtain the pre-compensation coefficient, the method further includes: Determining whether the central guide rod meets a target condition, wherein the target condition includes that the axial stress to which the central guide rod is subjected during use is less than a first preset axial stress and the ambient temperature is less than a first preset temperature; If not, the step of calculating the sum of the temperature compensation strain, the relaxation compensation, and the creep compensation to obtain the pre-compensation coefficient is performed; If satisfied, the sum of the temperature compensation strain and the relaxation compensation is calculated to obtain the pre-compensation coefficient.

10. The method according to claim 7, characterized in that The target parameter includes the temperature compensation strain, wherein the temperature compensation strain is calculated according to the following formula: ε1=a(T MAX +100-T0); Wherein, ε1 is the temperature compensation strain, a is the linear expansion coefficient of the material used for the central guide rod, T MAX is the maximum ambient temperature of the center guide rod during use, and T0 is the assembly temperature of the center guide rod.

11. The method according to claim 7, characterized in that The target parameter includes the relaxation compensation amount, wherein the relaxation compensation amount is calculated according to the following formula: ε2=[1 / (1-P)-1]ε1; Among them, ε2 is the relaxation compensation amount, and P is the relaxation rate of the material used for the central guide rod.

12. The method according to claim 7, characterized in that The target parameter includes the creep compensation amount, wherein the creep compensation amount is calculated according to the following formula: e3=Aσ 5.65 T 0.47 ; Wherein, ε3 is the creep compensation amount, A is the material constant of the center guide rod, σ is the creep stress on the center guide rod, and T is the creep time of the center guide rod.

13. The method according to claim 5, characterized in that The central guide rod comprises a first end and a second end spaced apart in the axial direction, the hollow insulator comprises a hollow insulating tube, a first flange and a second flange, the first flange is fixedly connected to the first end, the driving member comprises a threaded knob, and the step of stretching the central guide rod by using the driving member comprises: Connecting the first end to the hollow insulating tube through the first flange; Sleeving the second flange on the second end portion, and connecting the second flange to the hollow insulating tube; The threaded knob is sleeved on the second end portion, and the threaded knob is rotated. After the threaded knob abuts against the second flange, the threaded knob is further rotated to stretch the central guide rod.

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