Preparation method of composite insulator

Abstract

The invention discloses a preparation method of a composite insulator, and the method comprises the steps: S110, an insulating tube and a flange are prepared respectively, an umbrella skirt is prepared at the periphery of the insulating tube, the outer wall of the end part of the insulating tube is provided with at least one first annular groove, the flange comprises a flange tube and a flange plate, the flange plate covers one end of the flange tube, and the flange plate covers the other end of the flange tube; at least one second annular groove and at least one annular sealing groove are formed in the inner wall of the flange pipe; s120, the sealing piece is placed in the annular sealing groove, and the fixing ring is placed in the second annular groove; s130, the insulating pipe is inserted into the flange pipe, the fixing ring is located in a fixing groove formed by matching the first annular groove and the second annular groove, and an insulator prefabricated part is formed; and S140, carrying out crimping treatment on the insulator prefabricated member so as to fix the flange, the fixing ring, the sealing member and the insulating tube together to form the composite insulator. While the connection strength of the composite insulator is ensured, the production efficiency is improved, the preparation cost is reduced, and the sealing performance is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of power transmission and transformation insulation equipment, and in particular to a method for preparing a composite insulator. Background Art

[0002] Composite insulators are currently widely used in the field of power transmission and transformation insulation technology. The main structure of a composite insulator typically consists of a flange made of metal and a hollow insulating tube made of composite material. Currently, the mainstream connection technologies for composite and metal materials include adhesive bonding and crimping.

[0003] Crimping primarily involves squeezing metal materials to produce irreversible plastic deformation and tightly engage the composite material, thereby transmitting force through friction and mechanical engagement between the two. Due to the limited coefficient of friction between composite and metal materials, a high engagement force is required to ensure a successful connection. Therefore, this technology is generally used to connect solid composite rods. If the target material is a composite pipe, the high crimping force can easily damage the pipe, while the connection is poor if the pipe remains intact. Furthermore, since solid rods do not require sealing, existing crimping technology lacks supporting sealing technology, making it difficult to meet the sealing requirements of pipes. Consequently, existing composite insulator flanges and insulating pipes are typically connected using glue. Glue connection mainly involves injecting glue into the gap between the flange and the pipe, causing it to solidify and form a solidified glue layer, thereby connecting the flange and the insulating tube for force transmission. During processing, it is necessary to ensure that the glue can fill the gap and completely solidify in the gap. To this end, the flange needs to undergo a lot of additional processing to prepare glue injection holes, glue flow channels and other structures to ensure that the glue flow path is unobstructed. At the same time, it takes a long time to heat the pipe and flange to fully solidify the glue in the gap between the two. Therefore, the implementation of glue connection requires not only high-temperature resistant flanges and pipes, but also special glue binding machines that can inject glue and heat, and a lot of man-hours, resulting in a relatively high overall cost. Summary of the Invention

[0004] The main technical problem solved by the present application is to provide a method for preparing a composite insulator, which can ensure the connection strength and load capacity of the composite insulator while improving production efficiency, reducing preparation costs and enhancing its sealing performance.

[0005] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide a method for preparing a composite insulator, comprising the following steps: S110: preparing an insulating tube and a flange separately, and preparing an umbrella skirt on the outer periphery of the insulating tube, wherein the outer wall of the end of the insulating tube is provided with at least one first annular groove, the flange includes a flange tube and a flange plate, the flange plate covers one end of the flange tube, and the inner wall of the flange tube is provided with at least one second annular groove and at least one annular sealing groove; S120: placing the seal into the annular sealing groove and placing the fixing ring into the second annular groove; S130: inserting the insulating tube into the flange tube so that the fixing ring is located in the fixing groove formed by the first annular groove and the second annular groove to form an insulator preform; S140: crimping the insulator preform to fix the flange, the fixing ring, the seal and the insulating tube together to form a composite insulator.

[0006] Preferably, step S110 includes: after forming the main body structure of the insulating tube and the flange, grinding the outer wall of the insulating tube and the inner wall of the flange tube; cutting the insulating tube and the flange to form a first annular groove on the insulating tube, and forming a second annular groove and an annular sealing groove on the flange tube, wherein the number of the first annular groove and the second annular groove are both multiple and arranged one-to-one, the ratio of the depth of the first annular groove to the spacing between two adjacent first annular grooves is greater than or equal to one-third, and the depth of the second annular groove is greater than or equal to the depth of the first annular groove; the number of the annular sealing grooves is multiple, and the multiple annular sealing grooves are distributed at intervals along the axial direction of the insulating tube.

[0007] Preferably, before step S120, the method further includes: preparing a fixing ring; wherein the fixing ring is an integrated structure, and a through groove is provided on the fixing ring, and the through groove penetrates the fixing ring in the radial direction of the fixing ring and in the axial direction parallel to the fixing ring, and the through groove includes a first groove wall and a second groove wall that are arranged opposite to each other in the circumferential direction of the fixing ring, and the angle between the first groove wall and the second groove wall is in the range of 5°-10°; or, the fixing ring is a split structure, and the fixing ring includes a plurality of independently arranged arc rings, and the central angle of each arc ring is less than or equal to 180°, and the sum of the central angles of the plurality of arc rings is slightly less than or equal to 360°.

[0008] Preferably, the step of preparing the fixing ring further comprises: processing rounded corners on the edge of the fixing ring.

[0009] Preferably, step S120 includes: first compressing the seal so that the seal is inserted into the flange tube; moving the seal along the inner wall of the flange tube to the corresponding annular sealing groove, resetting the seal so that the outer side of the seal is installed in the annular sealing groove.

[0010] Preferably, step S120 includes: when the fixing ring is an integrated structure, first compressing the radial direction of the fixing ring so that the fixing ring is inserted into the flange tube; moving the fixing ring along the inner wall of the flange tube to the corresponding second annular groove, resetting the fixing ring, so that the outer side of the fixing ring is stuck in the second annular groove; or, when the fixing ring is a split structure, placing multiple arc rings into the corresponding second annular grooves in turn.

[0011] Preferably, step S130 includes: inserting the insulating tube into the fixing ring at the same time, so that the inner side of the fixing ring is inserted into the corresponding first annular groove, thereby limiting the fixing ring in the fixing groove.

[0012] Preferably, after step S130 and before step S140, the fitting clearance between the insulating tube and the flange tube is equal to the larger value of the depth of the first annular groove and half of the elastic deformation of the flange tube in the radial direction of the flange tube.

[0013] Preferably, step S140 includes: loading the insulator preform into a crimping machine, applying crimping pressure in the crimping area on the flange for crimping, wherein the crimping length of the crimping area is greater than or equal to a length threshold, and the crimping pressure is less than or equal to a first ratio.

[0014] Preferably, after step S140, the method further includes: filling the insulating tube with insulating gas, wherein the insulating gas is sulfur hexafluoride gas, nitrogen or air.

[0015] The beneficial effects of this application are as follows: Unlike the prior art, this application achieves a crimped connection of the composite insulator by providing a fixing ring between the flange and the insulating tube. This allows for a high connection strength at low crimping pressure, ensuring a secure connection between the flange and the insulating tube. Furthermore, this eliminates the need for additional design and processing of flange glue injection holes and glue flow channels, which are required in glue assembly technology. Furthermore, the glue injection process is eliminated, saving the labor required for injecting glue and waiting for the glue to solidify, thereby increasing production efficiency and reducing production costs. Furthermore, the pipe and flange do not need to be heated, preventing the insulating tube from thermally degenerating and affecting product quality.

[0016] In addition, the present application also ensures the sealing performance between the flange tube and the insulating tube through a seal. On the one hand, it can prevent external water vapor from invading the interior of the insulating tube along the interface between the flange tube and the insulating tube, and on the other hand, it can also prevent the filling material (such as filling gas) inside the insulating tube from leaking out. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a partial structural cross-sectional view of an embodiment of the composite insulator of the present application;

[0018] Figure 2 This is a partial structural cross-sectional view of an embodiment of the insulating tube of the present application;

[0019] Figure 3 This is a schematic structural diagram of an embodiment of a fixing ring of the present application;

[0020] Figure 4 is a cross-sectional view of an embodiment of a fixing ring of the present application;

[0021] Figure 5 It is a structural schematic diagram of another embodiment of the fixing ring of the present application;

[0022] Figure 6 It is a schematic flow chart of one embodiment of the preparation method of the present application. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and effects of this application more clear and explicit, the present application is further described in detail below with reference to the accompanying drawings and examples. Obviously, the described examples are only some of the examples of this application, not all of them. Based on the examples in this application, all other examples obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] See Figure 1 , Figure 1 This is a partial structural cross-sectional view of an embodiment of a composite insulator 10 of the present application. The composite insulator 10 includes an insulating tube 11, a flange 12, a fixing ring 13, and a seal 14. The insulating tube 11 is a hollow tubular structure, specifically a circular tube structure with both ends through. The material of the insulating tube 11 is a composite material, specifically a glass fiber, basalt fiber or aramid fiber impregnated with epoxy resin composite material. The outer wall of the end of the insulating tube 11 is provided with at least one first annular groove 111, and each first annular groove 111 is arranged along the circumference of the insulating tube 11 around the outer wall of the end of the insulating tube 11, and the depth of the first annular groove 111 is t i The first annular groove 111 is smaller than the wall thickness of the insulating tube 11 , that is, the first annular groove 111 does not penetrate the side wall of the insulating tube 11 .

[0025] The outer periphery of the insulating tube 11 is further provided with an shed. The specific structure and size of the shed can be realized by using existing technology according to the insulation requirements of the composite insulator 10 and are not specifically limited here.

[0026] The flange 12 includes a flange tube 121 and a flange plate 122. The flange tube 121 is a hollow tubular structure, specifically a circular tube structure. One end of the flange tube 121 is open, and the flange tube 121 is sleeved on the end of the insulating tube 11 through the opening. The other end of the flange tube 121 is sealed by a flange plate 122. The flange plate 122 is located on the side of the flange tube 121 away from the insulating tube 11. The flange plate 122 and the flange tube 121 are integrally arranged to form the flange 12, or the flange plate 122 and the flange tube 122 are connected together by welding or other means to form the flange 12. The material of the flange 12 includes metal. The inner wall of the flange tube 121 is provided with at least one second annular groove 123 and at least one annular sealing groove 124. The second annular groove 123 is arranged on the inner wall of the flange tube 121 along the circumference of the flange tube 121. The depth of the second annular groove 123 is t f The second annular groove 123 is smaller than the wall thickness of the flange tube 121, that is, the second annular groove 123 does not penetrate the side wall of the flange tube 121. The opening of the second annular groove 123 faces inward, that is, toward the first annular groove 111, and the opening of the first annular groove 111 faces outward, that is, toward the second annular groove 123. The second annular groove 123 and the first annular groove 111 are correspondingly arranged in the axial direction of the composite insulator 10 to cooperate to form a fixing groove (not shown). That is, the fixing groove is arranged along the circumference of the composite insulator 10 between the flange 12 and the insulating tube 11 to form an annular cavity for mounting the fixing ring 13. At the same time, the annular sealing groove 124 is arranged around the inner wall of the flange tube 121 along the circumference of the flange tube 121. The depth of the annular sealing groove 124 is less than the wall thickness of the flange tube 121, that is, the annular sealing groove 124 does not penetrate the side wall of the flange tube 121. The opening of the annular sealing groove 124 is inward, that is, toward the insulating tube 11. The seal 14 is fixedly arranged in the annular sealing groove 124. The seal 14 can be a sealing ring. The material of the seal 14 can be a material with good sealing performance, such as silicone rubber; the cross-sectional shape of the seal 14 can be circular, rectangular, etc.

[0027] The retaining ring 13 is mounted on the insulating tube 11 and positioned in the retaining groove. The insulating tube 11, retaining ring 13, seal 14, and flange 12 are securely connected via a crimping process. The retaining ring 13 can be made of a material with good plasticity, such as aluminum alloy, steel, or resin. The axial length of the crimping area on the flange tube 121 is defined as the crimping length H.

[0028] The present application uses a crimping process to press the flange 12 onto the outside of the end of the insulating tube 11. During the crimping process, the diameter of the flange 12 is reduced, and the flange 12 is squeezed by external force to undergo irreversible plastic deformation, and tightly bites the fixing ring 13, the seal 14 and the insulating tube 11. Since the composite insulator 10 of the present application has a fixing ring 13 embedded between the flange 12 and the insulating tube 11, the inner side of the fixing ring 13 is inserted into the outer wall of the insulating tube 11, and the outer side of the fixing ring 13 is inserted into the inner wall of the flange 12, the friction and mechanical bite force between the flange 12 and the insulating tube 11 are increased, so that a higher connection strength can be obtained under a lower crimping pressure, ensuring a stable connection between the flange 12 and the insulating tube 11, while preventing the insulating tube 11 from being damaged due to excessive crimping pressure. In addition, since the present application realizes the fixed connection between the flange 12 and the insulating tube 11 through the crimping process, the trouble of additional design and processing of the glue injection holes and glue flow channels on the flange 12 in the gluing technology is eliminated, and the glue injection process is eliminated, which saves the labor hours of injecting glue and waiting for the glue to solidify, speeds up production efficiency, and at the same time, there is no need to heat the insulating tube 11 and the flange 12 to prevent the insulating tube 11 from being deformed by heat and affecting product quality.

[0029] At the same time, the present application also provides a seal 14 between the flange tube 121 and the insulating tube 11. The seal 14 is located in the annular sealing groove 124, and after crimping, the seal 14 is tightly connected to the inner wall of the flange tube 121 and the outer wall of the insulating tube 11, so that the seal 14 can ensure the sealing performance between the flange tube 121 and the insulating tube 11. Specifically, on the one hand, the seal 14 can prevent external water vapor from invading the interior of the insulating tube 11 along the interface between the flange tube 121 and the insulating tube 11, thereby preventing the insulating tube 11 from being corroded by external water vapor. On the other hand, it can also prevent the filler (such as filling gas) inside the insulating tube 11 from leaking.

[0030] Optionally, continue to Figure 1 The first annular groove 111 and the second annular groove 123 are both rectangular grooves. Optionally, the sizes of the two can be the same or different, as long as they can be provided with the corresponding clamping ring 13, and this application does not make any specific restrictions.

[0031] Optionally, continue to Figure 1 The annular sealing groove 124 may also be a rectangular groove. The depth of the annular sealing groove 124 may be equal to or different from the depth of the second annular groove 123 , as long as the annular sealing groove 124 can fix the sealing member 14 .

[0032] The first annular groove 111 and the second annular groove 123, each with a rectangular cross section, can cooperate with the rectangular cross section of the fixing ring 13. The annular sealing groove 124, also with a rectangular cross section, facilitates installation of the seal 14 and is easy to process. Furthermore, the bottom wall of the rectangular groove can withstand radial pressure, while the side wall of the rectangular groove can withstand axial pressure, thereby ensuring connection strength.

[0033] Optionally, the number of the first annular groove 111 and the number of the second annular groove 123 are both multiple, and the multiple first annular grooves 111 and the multiple second annular grooves 123 are distributed at intervals along the axial direction of the insulating tube 11. The multiple first annular grooves 111 and the multiple second annular grooves 123 are arranged in a one-to-one correspondence, and the corresponding first annular grooves 111 and the second annular grooves 123 cooperate to form a fixed groove, and a fixed ring 13 is fixedly arranged in each fixed groove. By fixing the multiple fixing rings 13 through multiple groups of fixing grooves, the connection strength between the insulating tube 11 and the flange 12 can be ensured, and the more the number of fixing grooves and fixing rings 13, the better the connection strength. Specifically, the number of fixing grooves and fixing rings 13 is greater than or equal to three groups. At the same time, considering the processing time, production efficiency and production cost, the fewer the number of fixing grooves and fixing rings 13, the lower the manufacturing cost. Therefore, considering both connection strength and manufacturing cost, in this embodiment, the number of first annular grooves 111 and second annular grooves 123 is three. One first annular groove 111 and one second annular groove 123 form one fixing groove, so the number of fixing grooves is also three, and the number of fixing rings 13 is also three. In other embodiments, the number of fixing grooves and fixing rings 13 can be greater as long as the connection requirements are met, and this is not specifically limited here.

[0034] The number of the annular sealing groove 124 can be one or more, see Figure 1 In one embodiment, there are multiple annular sealing grooves 124, and each annular sealing groove 124 is provided with a sealing member 14. It is understood that the provision of multiple annular sealing grooves 124 can further enhance the sealing performance between the insulating tube 11 and the flange tube 121. At the same time, considering the processing time, production efficiency and production cost, the fewer the annular sealing grooves 124 and the sealing member 14, the lower the manufacturing cost and the higher the preparation efficiency. Therefore, considering the sealing performance and manufacturing cost, in this embodiment, as shown in FIG. Figure 1 As shown, there are two annular sealing grooves 124 and two sealing members 14 .

[0035] Continue reading Figure 1The second annular groove 123 closest to the flange 122 is defined as the first target groove, the second annular groove 123 farthest from the flange 122 is defined as the second target groove, and the second annular groove 123 adjacent to the second target groove is defined as the third target groove. There are multiple annular sealing grooves 124, and the multiple annular sealing grooves 124 are distributed at intervals along the axial direction of the insulating tube 11. A sealing member 14 is fixedly arranged in each annular sealing groove 124, one of the annular sealing grooves 124 is located between the first target groove and the flange 122, and one annular sealing groove 124 is located between the second target groove and the third target groove.

[0036] Specifically, the seal 14 in the annular sealing groove 124 between the second target groove and the third target groove can prevent the intrusion of external water vapor, and the seal 14 in the annular sealing groove 124 between the first target groove and the flange 122 can prevent the leakage of the filler in the insulating tube 11. Therefore, the above arrangement can effectively prevent the intrusion of external water vapor into the interior of the insulating tube 11 and effectively prevent the leakage of the filler in the insulating tube 11, thereby enhancing the insulation performance of the composite insulator 10.

[0037] Of course, in other embodiments, an annular sealing groove 124 may be provided between any two adjacent second annular grooves 123 . The present application does not limit the number and specific positions of the annular sealing grooves 124 .

[0038] Optionally, see Figure 2 and combined Figure 1 , Figure 2 This is a partial structural cross-sectional view of an embodiment of the insulating tube 11 of the present application. Figure 2 The structure of the side wall of the insulating tube 11 is magnified. A protrusion 112 is formed between two adjacent first annular grooves 111 on the insulating tube 11. The ratio of the depth of the first annular groove 111 to the distance between the two adjacent first annular grooves 111 is greater than or equal to one third.

[0039] When the composite insulator 10 is subjected to a load, the fixing ring 13 transmits force to the insulating tube 11 along a direction parallel to the axial direction of the insulating tube 11 through shearing action. Figure 2 The force diagram of the first annular groove 111 is shown, and the normal stress σ on the side wall of the first annular groove 111 of the insulating tube 11 is shown. a And the shear stress τ of the protrusion 112 between two adjacent first annular grooves 111. The figure also shows that the depth of the first annular groove 111, that is, the height of the i-th protrusion 112 in the radial direction of the insulating tube 11 along the axial direction of the insulating tube 11 is t i The distance between two adjacent first annular grooves 111, that is, the height of the i-th protrusion 112 in the axial direction of the insulating tube 11, is h i .

[0040] Since the material of the insulating tube 11 is a composite material, and the shear performance of the composite material is mainly measured by standard components, the stress form of the standard components in the test is the same as that of the standard components. Figure 2 The force form of the protrusion 112 in the same, according to the test specifications in this field, the ratio of the length of the compression surface to the length of the shear surface of the standard component is 7:20, about 1:3, and the shear strength of the standard component is f v This means that when the ratio of the height of the protrusion 112 in the radial direction of the insulating tube 11 to its height in the axial direction of the insulating tube 11 (ie the depth t i The distance h between two adjacent first annular grooves 111 i The ratio of i / h i ≥1 / 3, the shear strength of the composite material can be maximized. i If it is too large, it will lead to an increase in the amount of cutting during the processing of the insulating tube 11, resulting in material waste. i / h i ≈1 / 3 is the best value.

[0041] When t i / h i Take 1 / 3, that is, each bump 112 can provide about f v When the shear strength is greater than τ, within the range of the crimping length H, the maximum shear strength τ that the insulation tube 11 can provide is max ∑h i f v / H.

[0042] Furthermore, in order to ensure that the strength of the protrusion 112 can be properly exerted, the first annular groove 111 also needs to be designed in a certain way. The height h of the first annular groove 111 along the axial direction of the insulating tube 11 is d The depth t along the radial direction of the insulating tube 11 i The relationship between the first annular groove 111 and the insulating tube 11 in the axial direction needs to be determined according to the yield strength of the fixing ring 13. d Calculate according to the following formula: d =h r +Δh, where h r is the thickness of the fixing ring 13 in the axial direction of the insulating tube 11, and Δh is the maximum allowable processing error of the fixing ring 13. According to the force balance, the average normal stress σ of the protrusion 112 a =h i f v / t i Therefore, when the forces are balanced, the average normal stress on the fixing ring 13 is also σ aAccording to the von Mises criterion, the fixing ring 13 reaches the yield strength f y1 The shear stress τ that can be provided y ((f y1 2 -σ a 2 ) / 3) 0.5 From the balance of local pressure and shear force of the fixing ring 13, we can get: h r =σ a t i / τ y The maximum allowable machining error Δh of the fixing ring 13 can be selected as Δh=0.1-0.5 mm according to the actual machining accuracy.

[0043] Optionally, see Figure 3 and Figure 4 , Figure 3 This is a structural diagram of an embodiment of the fixing ring 13 of the present application. Figure 4 This is a cross-sectional view of an embodiment of the fixing ring 13 of the present application. In one embodiment, the fixing ring 13 adopts an integrated design and is provided with a through groove 131. The through groove 131 penetrates the fixing ring 13 in the radial direction and in the direction parallel to the axial direction of the fixing ring 13. The through groove 131 includes a first groove wall 132 and a second groove wall 133 arranged opposite to each other in the circumferential direction of the fixing ring 13. The angle β between the first groove wall 132 and the second groove wall 133 must satisfy (360-β) / 360*πD r ≤d, where D r β is the maximum outer diameter of the fixing ring 13. To reduce material loss, the preferred range of β is 5°-10°. The above configuration provides the fixing ring 13 with an opening, allowing the fixing ring 13 to shrink to a certain extent. By compressing the distance between the first groove wall 132 and the second groove wall 133, the diameter of the fixing ring 13 can be reduced, thereby allowing the fixing ring 13 to be inserted into the flange 12. When the fixing ring 13 moves into the second annular groove 123, the fixing ring 13 can open under the action of its own elastic force. At this time, the distance between the first groove wall 132 and the second groove wall 133 increases, allowing the fixing ring 13 to be snapped into the second annular groove 123, and the insulating tube 11 can be inserted into the fixing ring 13.

[0044] Optionally, see Figure 4 The edge of the fixing ring 13 is provided with rounded corners to ensure that the sharp corners of the fixing ring 13 will not scratch the insulating tube 11.

[0045] See Figure 5 , Figure 5Schematic diagram of another embodiment of the fixing ring 13 of the present application. In another embodiment, the fixing ring 13 includes a plurality of independently arranged arcuate rings 134. The plurality of arcuate rings 134 are arranged around the insulating tube 11 and are all disposed in the fixing groove. The central angle of each arcuate ring 134 is less than or equal to 180°, and the sum of the central angles of the plurality of arcuate rings 134 is slightly less than or equal to 360°.

[0046] and Figure 3 The implementation method is different. Figure 5 The fixing ring 13 in the embodiment adopts a split design, and multiple arc rings 134 are arranged along the circumference of the insulating tube 11, thereby splicing to form the fixing ring 13, and at the same time, the central angle of each arc ring 134 is less than or equal to 180°. This setting can reduce the difficulty of placing the fixing ring 13 into the second annular groove 123. Specifically, multiple arc rings 134 can be placed in the fixing groove in turn, and since the central angle θ of each arc ring 134 is less than or equal to 180°, when placing the arc ring 131, the arc ring 134 can be clamped into the second annular groove 123 without radially compressing the arc ring 134.

[0047] The number of the arc-shaped rings 134 can be two, three, four or more, as long as the multiple arc-shaped rings 134 can be spliced ​​together to form the fixing ring 13 .

[0048] In one embodiment, the central angles of the plurality of arc-shaped rings 134 are equal, so that the arc-shaped rings 134 can be manufactured using the same mold during the manufacturing process, thereby reducing the manufacturing cost.

[0049] In one embodiment, taking into account the existence of processing errors, in order to avoid the sum of the final central angles of multiple arc rings 134 being greater than 360° and all arc rings 134 being unable to be placed in the second annular groove 123, the central angle of each arc ring 134 is set to be less than or equal to 180° minus the angular processing error.

[0050] Optionally, the depth t of the second annular groove 123 is f Greater than or equal to the depth t of the first annular groove 111 i , that is, t f ≥t i , to ensure that the fixing ring 13 can provide the shear strength obtained in the previous calculation when it yields.

[0051] Optionally, continue to Figure 1 The axial crimping length H between the insulating tube 11 and the flange tube 121 is greater than or equal to a length threshold, wherein the length threshold is based on the maximum shear strength that the insulating tube 11 can provide and the maximum load that the insulating tube 11 can withstand.

[0052] Specifically, the crimping length H needs to be determined based on the external force and the average shear stress τ in the crimping area. Common loads on the insulating tube 11 include internal pressure inside the tube, transverse force bending moment, and pressure. Among them, the force transmission path of the compressive load is relatively smooth, and the force can be transmitted directly from the end of the insulating tube 11 to the flange 122, and generally does not require a high-strength connection structure. The internal pressure load inside the tube can generally be equivalent to pull-out force and circumferential tension. The circumferential tension has little effect on the connection structure, and the main effect is the pull-out force. Therefore, the loads borne by the composite insulator 10 generally include equivalent pull-out force F and transverse force bending moment M. Among them, equivalent pull-out force F = pπD f 2 / 4+T s , where D f is the outer diameter of the insulating tube 11, p is the internal pressure of the insulating tube 11, T s is the total width of the annular sealing groove 124 in the crimping area, that is, the sum of the widths of the multiple annular sealing grooves 124 in the crimping area along the axial direction of the flange pipe 121. At this time, the length threshold corresponding to the equivalent pull-out force F is F / (πD f τ max )+T s Ignoring the force generated by the extrusion between the insulating tube 11 and the flange 12, that is, the transverse force bending moment M is completely offset by the shear stress, the transverse force bending moment M can be obtained by the following formula: M = 4*∫0 0.5 πτ max H(D / 2)sinα*sinα(D / 2)dα=π(D 2 / 4)τ max H, so when the lateral force bending moment is M, the length threshold is 4M / (τ max πD 2 )+T s , where D is the outer diameter of the flange pipe 121. Therefore, when the transverse bending moment M and the equivalent pull-out force F appear in combination, the crimping length H needs to be able to simultaneously meet the length threshold required by the transverse bending moment M and the equivalent pull-out force F. Therefore, the crimping length H ≥ 4M / (τ max πD 2 )+F / (πD f τ max )+T s Under the crimping length H, the composite insulator 10 can withstand the maximum load and the maximum shear strength.

[0053] Optionally, the product of the yield strength of the flange tube 121 and twice the wall thickness of the flange tube 121 is defined as a first product; the product of the circumferential compressive yield strength of the insulating tube 11 and twice the wall thickness of the insulating tube 11 is defined as a second product; the ratio of the sum of the first product and the second product to the outer diameter of the flange tube 121 after crimping is defined as a first ratio; wherein the pressure required for the crimping process, i.e., the crimping pressure P, is less than or equal to the first ratio.

[0054] Specifically, see Figure 1 Under the action of the crimping force, the flange tube 121 undergoes plastic deformation inward, and its diameter is reduced. Therefore, the crimping pressure P needs to ensure that the deformation of the flange 12 is sufficient to fill the fitting gap t between the flange 12 and the insulating tube 11. s , and will not cause damage to the insulating tube 11 and the flange 12. Since the flange tube 121 and the flange plate 122 are often connected together by welding or casting, a connection seam is formed at the connection between the flange tube 121 and the flange plate 122, that is, a weld seam is formed by welding, and a casting seam is formed by casting. The second annular groove 123 and the annular sealing groove 124 should be spaced apart from the connection seam. In other words, the crimping length H should be less than or equal to the total length of the flange tube 121 minus the width of the connection seam, to ensure that the connection seam between the flange tube 121 and the flange plate 122 will not be pressed by the crimping machine during the crimping process, thereby causing product damage.

[0055] In another embodiment, the flange 12 also includes a reinforcing rib, which is arranged on the periphery of the flange tube 121 and connects the flange tube 121 and the flange plate 122. The end where the reinforcing rib is connected to the flange tube 121 is defined as the first end, that is, the end of the reinforcing rib away from the flange plate 122 is the first end. At this time, in the axial direction of the insulating tube 11, the distance between any second annular groove 123, any annular sealing groove 124 and the flange plate 122 is greater than the distance between the first end and the flange plate 122. That is to say, any second annular groove 123, any annular sealing groove 124 are spaced apart from the first end of the reinforcing rib, so that the crimping length H is less than or equal to the total length of the flange tube 121 minus the length of the reinforcing rib in the axial direction of the insulating tube 11, so as to ensure that during the crimping process, the reinforcing rib will not be pressed by the crimping machine and cause product damage.

[0056] The crimping pressure P needs to ensure that the flange tube 121 yields and the insulating tube 11 is not damaged. Therefore, the minimum value of the crimping pressure P is P min =f y (Dd) / D, where f y is the yield strength of the flange pipe 121, D is the outer diameter of the flange pipe 121, and d is the inner diameter of the flange pipe 121. The maximum value of the crimping pressure P is P max =(f y *(Dd)+f uf *(D f -d f )) / (D-2t s ), f uf D is the circumferential compressive yield strength of the insulating tube 11. According to the technical experience in this field, it can generally be estimated based on 0.8 times the measured circumferential compressive strength. f d fare the outer diameter and inner diameter of the insulating tube 11, t s is the fit clearance, equal to 0.5*(dD f ). Among them, the first product is f y *(Dd), (Dd) is twice the wall thickness of flange pipe 121, the second product is f uf *(D f -d f ), (D f -d f ) is twice the wall thickness of the insulating tube 11, (D-2t s ) is the outer diameter of the flange pipe 121 after crimping. The actual crimping pressure P can be taken as [P min ,P max ] interval, it is best to use P max To ensure sealing.

[0057] Optionally, before crimping, the fitting clearance t between the insulating tube 11 and the flange tube 121 on one side is s Equal to the depth t of the first annular groove 111 i , the larger value of half of the elastic deformation of the flange tube 121 in its radial direction.

[0058] Specifically, see Figure 1 , in general, the fit clearance t s It needs to be larger than the elastic displacement before the flange pipe 121 undergoes plastic deformation to maximize the crimping effect and at the same time the clearance t s If it is too large, it will lead to waste of materials, and since the plastic deformation of the flange pipe 121 made of metal is limited, an excessively large fitting clearance t s It is easy to cause damage to the flange pipe 121. s In the initial crimping condition, which is not zero, the inner surface of the flange tube 121 is a free surface and is not subjected to stress, while the outer surface is subjected to the crimping pressure P. This indicates that the radial stress of the flange tube 121 is between 0 and P, and the radial thickness (Dd) / 2 is relatively small relative to the diameter D. The radial deformation in the elastic stage is proportional to the thickness and radial stress. The stress in the circumferential direction perpendicular to the radial direction on the flange tube 121, i.e., the hoop stress, is P*D / (Dd), and the circumferential circumference is πD. a , D a =(D+d) / 2, D a is the average value of the outer diameter and inner diameter of the flange pipe 121. Obviously, the circumferential stress of the flange pipe 121 is significantly greater than the radial stress, and the circumferential circumference is also significantly greater than the radial thickness. Therefore, the radial deformation of the flange pipe 121 can be ignored. The elastic limit of the metal material is f y , when the stress is less than f y When the flange pipe 121 undergoes only elastic deformation, the corresponding maximum elastic strain ε ef y / E, E is the elastic modulus of the metal material. When the radial stress is ignored, the circumferential deformation corresponding to the elastic deformation is δ E =ε e πD a , the corresponding radial deformation is δ Ec =ε e D a , so the unilateral fit clearance t s Should be no less than ε e D a / 2, accordingly, the condition for the metal material to not be damaged is t s <ε d D a / 2,ε d is the total strain that occurs when the metal fails, ε d Generally significantly greater than ε e , taking aluminum alloy as an example, its ε e About 0.3%, the total failure strain is greater than 2.3%, about 7.7ε e , Q355 steel is even more exaggerated, its ε e is 0.17%, the failure strain is 20.2%, and is about 101ε e , so t s Less than ε d D a / 2 This restriction is too broad and has almost no restrictive effect. Therefore, from the perspective of saving materials, a single-sided fit clearance t is set. s The depth t of the first annular groove 111 is used i , that is, set the unilateral fit clearance t s Equal to the depth t of the first annular groove 111 i .

[0059] Optionally, in some embodiments, the insulating tube 11 is filled with insulating gas, which may specifically be sulfur hexafluoride gas, nitrogen, or air, to ensure the insulating performance of the composite insulator 10 .

[0060] In one embodiment, the internal pressure of the insulating gas filled in the insulating tube 11 can be set according to specific circumstances:

[0061] In the first case, when the internal pressure deformation stiffness of the flange 12 is less than the internal pressure deformation stiffness of the insulating tube 11, the same internal pressure acts on the insulating tube 11 and the flange 12, and the deformation of the flange 12 will be greater than the deformation of the insulating tube 11. At this time, the internal pressure of the insulating gas filled in the insulating tube 11 shall not be greater than the residual contact pressure P between the flange 12 and the insulating tube 11 after crimping. ROtherwise, the compression of the seal 14 is likely to be offset by the deformation of the flange 12. The internal pressure deformation stiffness is defined as the radial deformation of the structure when one unit pressure is increased. For the flange 12, its internal pressure deformation stiffness K f =d(D+d) / 2 / E / (Dd), for the insulating tube 11, its internal pressure deformation stiffness K p =d f (D f +d f ) / 2 / E f / (D f -d f ).

[0062] Residual contact pressure P R It can be concluded from the following process that during the crimping process, after the flange pipe 121 enters the plastic deformation stage, the displacement of its elastic deformation is determined by the fitting clearance t s Offset, the rest of the displacement forming plastic deformation, it is known that the displacement of the inner wall of the flange tube 121 should be equal to the displacement of the outer wall of the insulating tube 11, and in actual circumstances, the elastic section and the reinforcement section of the composite material are more obvious. In the elastic section and the reinforcement section, the stress increases with the increase of strain. Therefore, even if the insulating tube 11 enters the plastic section in the circumferential direction, the ratio of the circumferential stress to the circumferential strain of the insulating tube 11 will not be significantly less than the elastic modulus of the insulating tube 11, and the circumferential strain ε of the insulating tube 11 is not significantly smaller than the elastic modulus of the insulating tube 11. rf =σ uf / E f , E f is the elastic modulus of the insulating tube 11 in the hoop direction, σ uf is the hoop stress of the insulating tube 11. Under the premise of ignoring the thickness change of the insulating tube 11 and the flange tube 12, the hoop stress σ of the insulating tube 11 is uf =(P*(D f +Dd)-f y *(Dd)) / (D f -d f ). The hoop strain ε of the insulating tube 11 rf The corresponding radial displacement is ε rf *R fa , R fa The radius of the circle formed by the center line of the wall of the insulating tube 11 is equal to (D f +d f ) / 2, where the radial strain of the wall of the insulating tube 11 itself is neglected. Therefore, when the crimping force is the maximum, the radial displacements of the insulating tube 11 and the flange 12 are both ε rf *R fa , the deformation of the flange tube 121 in the wall thickness direction is also ignored here.

[0063] When the crimping is unloaded, all materials will have corresponding stress unloading-strain rebound with their own elastic modulus as the slope. Assume that the circumferential strain of the wall centerline of the insulating tube 11 is ε lf , we can get the following relationship: E f ε lf t p =E(ε rf -ε lf -f y / E)t a , where t p is the wall thickness of the insulating tube, t a is the wall thickness of the flange tube 121, the left side of the equation is the residual circumferential compressive stress of the insulating tube 11 after crimping and unloading, and the right side of the equation is the additional circumferential tensile stress of the flange tube 121 after unloading due to the extrusion of the tube wall and its own elastic unloading. lf =(ε rf -f y / E) / (1+E f t p / (Et a )), according to the relationship between the hoop stress and the peripheral pressure of the thin-walled tube, P R =(D f -d f )E f ε lf / D f .

[0064] In the second case, when the internal pressure deformation stiffness of the flange 12 is greater than or equal to the internal pressure deformation stiffness of the insulating tube 11, the flange 12 and the insulating tube 11 will be pressed tighter and tighter as the internal pressure increases. At this time, the sealing effect will not fail due to excessive pressure. Therefore, the internal pressure of the insulating gas filled into the insulating tube 11 only needs to meet the strength requirements.

[0065] In one embodiment, multiple annular sealing grooves 124 are evenly spaced within the crimping area of ​​the flange 12 to avoid weakening the flange 12 due to the concentrated arrangement of multiple annular sealing grooves 124. Assuming there are Q annular sealing grooves 124, starting from a position close to the flange 122, the distance between the centerline of the i-th annular sealing groove 124 and the edge of the crimping area away from the flange 122 is iH / (Q+1), where i = 1, 2, ..., Q. The centerline refers to the annular line in the middle of the annular sealing groove 124 in the axial direction of the flange pipe 121.

[0066] The depth of the annular sealing groove 124 along the radial direction of the flange pipe 121 is defined as the depth of the annular sealing groove 124, and the depth of the annular sealing groove 124 before crimping is recorded as t m , the depth of the annular sealing groove 124 after crimping is recorded as tm1 , it is understandable that t m1 With t m Related, in setting t m When the annular sealing groove 124 is pressed, the depth t m1 Satisfaction: t m1 =ηD s In this embodiment, the sealing member 14 is a sealing ring with a circular cross section. s is the wire diameter of the seal 14, that is, the diameter of the circular cross-section of the seal 14; η = 1-S, S is the design compression rate of the seal 14. According to the technical specifications in this field, S is generally 16% to 25%, that is, the design compression rate can meet the requirements within this range. This is mainly because, on the one hand, the processing accuracy of the seal 14 can generally only reach 0.1mm level, and the wire diameter of the seal 14 is generally also in mm level. Therefore, an overly precise design compression rate is difficult to achieve with the existing processing level; on the other hand, an excessively high design compression rate will lead to a short service life of the seal 14, and an excessively low design compression rate will lead to a poor sealing effect of the seal 14.

[0067] The width b of the annular sealing groove 124 along the axial direction of the flange pipe 121 should satisfy: π(D f +t m1 )*b*t m1 =(1+p s )πD s0 (πD s 2 ) / 4, where p s D is the swelling ratio of the material of the seal 14. Usually, the swelling ratio of the material of the seal 14 is 30%. s0 The diameter of the center line of the seal 14 is the annular line where the center of each cross section of the seal ring is located. The specifications of the seal 14 can be selected according to national standards and combined with the size of the flange 12 to determine D s 、D s0 , and then determine t m1 t m 、b.

[0068] In estimating t m1 An approximate assumption needs to be introduced: the effect of plastic deformation on the material volume can be ignored. This assumption is based on the fact that the effect of plastic deformation on the material density is negligible. Therefore, it can be approximately assumed that plastic deformation does not affect the volume when the weight remains unchanged.

[0069] The residual strain of flange 12 in the circumferential direction is ε rf -ε lf -f y / E, where ε rfis the hoop strain of the insulating tube 11 during crimping, and the hoop strain of the wall centerline of the insulating tube 11 that is finally retained is ε lf , it should be noted that ε lf The corresponding elastic strain is the residual circumferential plastic strain ε rf -f y / E, since the volume remains unchanged, the radial plastic strain should be -ε rf +f y / E, then the corresponding change (increase) in the depth of the annular sealing groove 124 is (ε rf -f y / E)t m Generally, the relaxation of metal materials will not convert elastic strain into plastic strain too high, so the hoop elastic deformation - ε lf The corresponding radial elastic strain is vε lf , v is the Poisson's ratio of the metal material of the flange 12, which is generally 0.3 to 0.33. Here, the positive value refers to the compression deformation strain, so the depth of the annular sealing groove 124 is reduced by vε due to elastic deformation. lf t m , so we can get, t m1 =t m +(ε rf -f y / E)t m -vε lf t m .

[0070] The present application also provides a method for preparing a composite insulator 10, combining Figure 1 as well as Figure 6 , Figure 6 : is a schematic flow chart of an embodiment of the preparation method of the present application, which comprises:

[0071] S110: Prepare an insulating tube 11 and a flange 12 respectively, wherein the outer wall of the end of the insulating tube 11 is provided with at least one first annular groove 111, the flange 12 includes a flange tube 121 and a flange plate 122, the flange plate 122 covers one end of the flange tube 121, and the inner wall of the flange tube 121 is provided with at least one second annular groove 123 and at least one annular sealing groove 124.

[0072] In this step, the insulating tube 11 and flange 12 are formed separately. Specifically, after the main structures of the insulating tube 11 and flange 12 are formed, the outer wall of the insulating tube 11 and the inner wall of the flange tube 121 are polished to remove burrs and ensure a good connection. The insulating tube 11 and flange 12 are then cut according to the aforementioned design dimensions to form a first annular groove 111 on the insulating tube 11 and a second annular groove 123 and an annular sealing groove 124 on the flange tube 121.

[0073] Furthermore, an shed is prepared on the outer periphery of the insulating tube 11 .

[0074] S120 : placing the sealing member 14 into the annular sealing groove 124 and placing the fixing ring 13 into the second annular groove 123 .

[0075] Before this step, prepare the retaining ring 13. If the retaining ring 13 is a one-piece structure, the opening structure and dimensions of the retaining ring 13 are as described above. If the retaining ring 13 is a split structure, the central angles and dimensions of the multiple arcuate rings 131 are also as described above. Furthermore, rounded corners are processed on the edges of the retaining ring 13.

[0076] In this step, when placing the seal 14, the seal 14 can be compressed first, for example, radially compressed or directly folded, so that the seal 14 can be inserted into the flange tube 121, and then the seal 14 is moved along the inner wall of the flange tube 121. When the seal 14 moves to the corresponding annular sealing groove 124, the seal 14 is reset by its own elasticity, so that the outer side of the seal 14 is installed in the annular sealing groove 124.

[0077] When the fixing ring 13 is an integrated structure, when inserting the fixing ring 13, the fixing ring 13 can be compressed radially first so that the fixing ring 13 can be inserted into the flange tube 121, and then the fixing ring 13 is moved along the inner wall of the flange tube 121. When the fixing ring 13 moves to the corresponding second annular groove 123, the fixing ring 13 is reset radially by its own elasticity, so that the outer side of the fixing ring 13 is stuck in the second annular groove 123.

[0078] When the fixing ring 13 is a split structure, when inserting the fixing ring 13 , the plurality of arc-shaped rings 131 are sequentially placed into the corresponding second annular grooves 123 .

[0079] The present application does not restrict the order in which the seal 14 and the retaining ring 13 are placed. The seal 14 can be placed first, or the retaining ring 13 can be placed first. In one embodiment, the seal 14 and the retaining ring 13 can be placed in the order from the installation position to the flange 122. That is, the closer the installation position is to the flange 122, the earlier it is placed.

[0080] S130: Insert the insulating tube 11 into the flange tube 121 so that the fixing ring 13 is located in the fixing groove formed by the first annular groove 111 and the second annular groove 123 to form an insulator prefabricated part.

[0081] In this step, the insulating tube 11 is simultaneously inserted into the fixing ring 13, so that the inner side of the fixing ring 13 is inserted into the corresponding first annular groove 111, thereby limiting the fixing ring 13 in the fixing groove. At this time, the insulating tube 11 and the flange 12 in the formed insulator preform have not yet been crimped together, and the fitting clearance t between the insulating tube 11 and the flange tube 121 is t s As mentioned above.

[0082] S140 : performing a crimping process on the insulator prefabricated component to fix the flange 12 , the fixing ring 13 , the sealing member 14 , and the insulating tube 11 together to form a composite insulator 10 .

[0083] Specifically, the insulator preform is loaded into the crimping machine, and a crimping pressure P within the aforementioned range is applied in the crimping area on the flange 12 for crimping. The crimping length H is calculated according to the aforementioned formula. At this time, the flange 12 undergoes plastic deformation in the radial direction, and its diameter is reduced, tightly engaging the fixing ring 13, the seal 14 and the insulating tube 11. The seal 14 is tightly connected to the inner wall of the flange tube 121 and the outer wall of the insulating tube 11, so that the flange 12, the insulating tube 11, the seal 14 and the fixing ring 13 are crimped together.

[0084] After this step, the insulating tube 11 may be filled with insulating gas according to the aforementioned design pressure.

[0085] The above method can realize the crimping of the flange 12 and the insulating tube 11, and ensure the connection strength of the composite insulator 10 under the premise of ensuring that the insulating tube 11 is not damaged. At the same time, it eliminates the trouble of additionally designing and processing the flange glue injection hole and glue flow channel and other structures in the glue assembly technology, and eliminates the glue injection process, saving the labor hours of injecting glue and waiting for the glue to solidify, and speeding up production efficiency. At the same time, there is no need to heat the insulating tube 11 and the flange 12 to prevent the insulating tube 11 from being thermally denatured and affecting product quality. In addition, the seal 14 can also ensure the sealing performance between the flange tube 121 and the insulating tube 11. On the one hand, it can prevent external water vapor from invading the interior of the insulating tube 11 along the interface between the flange tube 121 and the insulating tube 11, and prevent the insulating tube 11 from being corroded by external water vapor. On the other hand, it can also prevent the filling material (such as filling gas) inside the insulating tube 11 from leaking out.

[0086] The above is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, 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 method for preparing a composite insulator, characterized in that: The preparation method comprises the following steps: S110: Prepare an insulating tube and a flange respectively, and prepare an shed skirt on the outer periphery of the insulating tube, wherein the outer wall of the end of the insulating tube is provided with at least one first annular groove, the flange includes a flange tube and a flange plate, the flange plate covers one end of the flange tube, and the inner wall of the flange tube is provided with at least one second annular groove and at least one annular sealing groove; S120: placing a sealing member into the annular sealing groove and placing a fixing ring into the second annular groove; S130: inserting the insulating tube into the flange tube so that the fixing ring is located in a fixing groove formed by the first annular groove and the second annular groove, thereby forming an insulator preform; S140: performing a crimping process on the insulator preform to fix the flange, the fixing ring, the sealing member, and the insulating tube together to form the composite insulator.

2. The preparation method according to claim 1, characterized in that The step S110 includes: After forming the main body structures of the insulating tube and the flange, grinding the outer wall of the insulating tube and the inner wall of the flange tube; The insulating tube and the flange are cut to form the first annular groove on the insulating tube, and the second annular groove and the annular sealing groove are formed on the flange tube, wherein the number of the first annular groove and the second annular groove are both multiple and arranged in a one-to-one correspondence, the ratio of the depth of the first annular groove to the spacing between two adjacent first annular grooves is greater than or equal to one-third, and the depth of the second annular groove is greater than or equal to the depth of the first annular groove; the number of the annular sealing grooves is multiple, and the multiple annular sealing grooves are distributed along the axial direction of the insulating tube at intervals.

3. The preparation method according to claim 1, characterized in that Before step S120, the method further includes: preparing the fixing ring; The fixing ring is an integral structure, and is provided with a through groove. The through groove penetrates the fixing ring in a radial direction and a direction parallel to the axial direction of the fixing ring. The through groove includes a first groove wall and a second groove wall that are arranged opposite to each other in the circumferential direction of the fixing ring. The angle between the first groove wall and the second groove wall is in the range of 5°-10°. Alternatively, the fixing ring is a split structure, and the fixing ring includes a plurality of independently arranged arc rings, the central angle of each arc ring is less than or equal to 180°, and the sum of the central angles of the plurality of arc rings is slightly less than or equal to 360°.

4. The preparation method according to claim 3, characterized in that The step of preparing the fixing ring further comprises: The edge of the fixing ring is rounded.

5. The preparation method according to claim 1, characterized in that The step S120 includes: First, the seal is compressed so that the seal is inserted into the flange pipe; the seal is moved along the inner wall of the flange pipe to the corresponding annular sealing groove, and the seal is reset so that the outer side of the seal is installed in the annular sealing groove.

6. The preparation method according to claim 3, characterized in that The step S120 includes: When the fixing ring is an integrated structure, the fixing ring is first compressed in the radial direction so that the fixing ring is inserted into the flange pipe; the fixing ring is moved along the inner wall of the flange pipe to the corresponding second annular groove, and the fixing ring is reset so that the outer side of the fixing ring is stuck in the second annular groove; Alternatively, when the fixing ring is a split structure, multiple arc-shaped rings are sequentially placed into the corresponding second annular grooves.

7. The preparation method according to claim 6, characterized in that The step S130 includes: The insulating tube is simultaneously inserted into the fixing ring so that the inner side of the fixing ring is inserted into the corresponding first annular groove, thereby limiting the fixing ring in the fixing groove.

8. The preparation method according to claim 1, characterized in that After step S130 and before step S140, the fitting clearance between the insulating tube and the flange tube is equal to the larger value of the depth of the first annular groove and half of the elastic deformation of the flange tube in the radial direction of the flange tube.

9. The preparation method according to claim 1, characterized in that The step S140 includes: The insulator preform is loaded into a crimping machine, and a crimping pressure is applied in a crimping area on the flange for crimping, wherein the crimping length of the crimping area is greater than or equal to a length threshold, and the crimping pressure is less than or equal to a first ratio.

10. The preparation method according to claim 1, characterized in that After step S140, the method further includes: The insulating tube is filled with insulating gas, wherein the insulating gas is sulfur hexafluoride gas, nitrogen gas or air.

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