A high-strength alumina suspension insulator for rectifiers and its manufacturing process

Abstract

This invention discloses a high-strength alumina suspension insulator for rectifiers and its manufacturing process, relating to the field of power equipment insulator technology. The high-strength alumina suspension insulator for rectifiers and its manufacturing process include a ceramic body, a steel head, a steel cap, and steel feet. The ceramic body adopts a composite gradient structure, divided from the inside out into a high-strength inner layer, a transitional middle layer, and a high-insulation outer layer. The inner hole of the ceramic head has a three-stage stepped structure transitioning through a conical surface. The steel head is equipped with a gradient screw, with micro-helical grooves on the outer side, forming a mechanical interlocking structure with the inner hole using a modified cement adhesive. The manufacturing process includes raw material preparation, ball milling, gradient molding, drying and trimming, glazing, sintering, and assembly. Precise control of each process parameter ensures the insulator's high strength and high insulation performance. This invention features a reasonable structural design, high strength, good insulation, secure assembly, long service life, and is suitable for the operating environment requirements of rectifiers.

Description

Technical Field

[0001] This invention relates to the field of power equipment insulator technology, specifically to a high-strength alumina suspension insulator for rectifiers and its manufacturing process. Background Technology

[0002] Suspension insulators are important insulating components in power systems, mainly used to suspend conductors and provide insulation. They are widely used in power equipment such as transformers and rectifiers. Among them, suspension insulators for rectifiers, due to their long-term operation in environments with strong electric fields and high temperature variations, have extremely high requirements for their strength, insulation performance, and structural stability.

[0003] Currently, most suspension insulators used in rectifiers employ a single material, alumina ceramic, which suffers from insufficient strength and poor toughness, making them prone to cracking and breakage during long-term service. Furthermore, the bonding method between the ceramic body and metal connectors such as steel heads and caps is relatively simple, often using ordinary cement adhesive, resulting in insufficient bond strength. This makes them susceptible to detachment under vibration, temperature changes, and other conditions, affecting the stable operation of the rectifier. In addition, the existing insulator manufacturing process is relatively crude, with imprecise control over parameters in key steps such as raw material proportioning, ball milling, and sintering, leading to significant fluctuations in product performance and making it difficult to meet the high-precision requirements of rectifiers.

[0004] Therefore, developing a suspension insulator for rectifiers that is high in strength, has good insulation performance, is firmly assembled, and has a stable and controllable production process has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength alumina suspension insulator for rectifiers and its manufacturing process, so as to solve the problems of insufficient strength, poor insulation performance and weak bonding of metal connectors in existing insulators mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-strength alumina suspension insulator for rectifiers, comprising a ceramic body, steel heads, and steel caps. The ceramic body has ceramic heads at its upper and lower ends, and each ceramic head has an inner hole. The inner hole has a three-stage stepped structure along the axial direction of the ceramic body, with conical transition surfaces between the steps. The ceramic body adopts a composite gradient structure design, consisting of a high-strength inner layer, a transitional intermediate layer, and a high-insulation outer layer, from the inside out. Two sets of steel heads are provided, each inserted into the inner hole, with micro-spiral grooves formed on its outer side. The steel cap is inserted into one set of steel heads; and a steel foot is inserted into the other set of steel heads.

[0007] Preferably, an umbrella body is provided on the outer side of the ceramic body, the umbrella body includes an outer umbrella and an inner umbrella, the diameter of the outer umbrella is larger than that of the inner umbrella, and the outer umbrella and the inner umbrella are distributed alternately.

[0008] Preferably, the inner hole includes a primary hole, a secondary hole, and a tertiary hole, wherein the inner diameter of the primary hole is greater than the inner diameter of the secondary hole, which is greater than the inner diameter of the tertiary hole, and a first transition tapered surface is provided between the primary hole and the secondary hole and between the secondary hole and the tertiary hole.

[0009] Preferably, the composite gradient structure of the ceramic body includes, from the inside to the outside, a high-strength inner layer, a transition intermediate layer, and a high-insulation outer layer in a radial direction. The high-strength inner layer has a higher alumina content than the transition intermediate layer and contains zirconia toughening agent. The transition intermediate layer has a higher alumina content than the high-insulation outer layer. The high-insulation outer layer contains mica powder. The inner holes are formed on the inner sides of both ends of the high-strength inner layer, and the umbrella body is connected to the outer side of the high-insulation outer layer and is made of the same material as the high-insulation outer layer.

[0010] Preferably, the top of the steel head has a threaded hole, a cap ring is fixedly connected to the outside of the steel head, the cap ring is sleeved on the outside of the ceramic head, a gradient screw is connected to the bottom of the steel head, the gradient screw is provided with a first gradient, a second gradient and a third gradient, a second transition conical surface is provided between the first gradient and the second gradient and the second gradient and the third gradient, micro-helical grooves are provided on the outside of the first gradient, the second gradient and the third gradient, the gradient screw is adapted to the inner hole and inserted into the inner side of the inner hole, and the gradient screw and the inner hole are filled with modified cement adhesive, and after the modified cement adhesive is cured, it forms a mechanical interlocking structure with the micro-helical grooves through a threaded connection.

[0011] Preferably, the steel cap has a slot on the outer side and a groove on the inner side, and a first bolt is connected to the bottom of the steel cap. The first bolt is inserted into the threaded hole of the upper set of steel heads.

[0012] Preferably, the steel foot is adapted to the slot on the inner side of the steel cap and can be engaged in the slot through the slot opening. A second bolt is connected to the top of the steel foot, and the second bolt is inserted into the threaded hole of a set of steel heads below.

[0013] Preferably, the manufacturing process for high-strength alumina suspension insulators for rectifiers is characterized by comprising the following steps: Step 1, ball milling: The raw material is ball milled to control the fineness of the slurry; Step 2, Gradient Molding: A layered casting molding process is adopted, in which high-strength inner layer slurry, transitional intermediate layer slurry and high-insulation outer layer slurry are poured in sequence; Step 3, Drying and trimming: The formed blank is dried and then trimmed to obtain a smooth blank; Step 4: Glazing treatment: Glaze the unglazed body; Step 5, sintering treatment: The glazed body is placed in a high-temperature kiln for sintering to obtain alumina ceramic insulator body; Step 6, Assembly: Assemble the steel head into the inner hole of the ceramic body head. Fill the space between the gradient screw of the steel head and the inner hole of the ceramic body with modified cement adhesive. After assembly, apply axial preload and perform curing and heat treatment.

[0014] The technical effects and advantages of this invention are as follows: 1. This rectifier uses high-strength alumina suspension insulators. The ceramic body adopts a composite gradient structure, which is divided into a high-strength inner layer, a transition middle layer and a high-insulation outer layer from the inside out. The high-strength inner layer is reinforced with zirconium oxide toughening agent to ensure high strength and high toughness. The high-insulation outer layer is reinforced with mica powder to improve insulation performance. The transition middle layer achieves a smooth transition of performance and avoids stress concentration at the interface, effectively solving the problems of insufficient strength and poor insulation performance of existing insulators.

[0015] 2. This rectifier uses high-strength alumina suspension insulators with a three-stage stepped structure in the inner bore. Conical transition surfaces are provided between each stage, creating a gradient fit with the steel-headed gradient screw. This design effectively disperses and transmits axial tensile force in stages, eliminating the stress concentration problem inherent in traditional cylindrical bore structures under long-term vibration conditions.

[0016] 3. This rectifier uses high-strength alumina suspension insulators. Micro-spiral grooves are created on the outer side of the steel head, forming a mechanically interlocking structure after curing with modified cement adhesive. This significantly improves the bonding strength and pull-out resistance between the steel head and the ceramic body. A cover ring fitted onto the outer side of the ceramic head further enhances the structural stability.

[0017] 4. The rectifier uses high-strength alumina suspension insulators with staggered outer and inner umbrellas on the outside of the ceramic body, which increases the surface area, improves insulation performance, and prevents impurities from adhering, further ensuring the insulation effect and making it suitable for the strong electric field working environment of the rectifier.

[0018] 5. The rectifier uses the production process of high-strength alumina suspension insulators. Strontium carbonate is added to the billet formula to promote the growth of corundum crystal phase, zirconium oxide is added to achieve phase transformation toughening, and nano alumina is added to fill micropores to improve density, so that the ceramic body has excellent mechanical and electrical properties.

[0019] 6. The rectifier uses a high-strength alumina suspension insulator manufacturing process, and adopts a separate glazing process for the head and umbrella parts. Different glaze systems are designed for the functional requirements of different parts. The head blocking glaze layer effectively inhibits sodium ion electromigration, the functional glaze layer gives self-cleaning properties, and the umbrella surface glaze layer ensures coverage and dirt resistance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall cross-sectional structure of the present invention; Figure 3 This is a schematic diagram of the structure of the ceramic body of the present invention; Figure 4 This is a schematic cross-sectional view of the ceramic body of the present invention; Figure 5 This is a schematic diagram of the structure of the steel head of the present invention; Figure 6 This is a schematic diagram of the bottom structure of the steel head of the present invention; Figure 7 This is a schematic diagram of the structure of the steel cap of the present invention; Figure 8 This is a schematic diagram of the side cross-sectional structure of the steel cap of the present invention; Figure 9 This is a schematic diagram of the steel foot structure of the present invention.

[0022] In the diagram: 1. Porcelain body; 11. Porcelain head; 12. Umbrella body; 121. Outer umbrella; 122. Inner umbrella; 13. Inner hole; 131. Primary hole; 132. Secondary hole; 133. Tertiary hole; 134. First transition conical surface; 14. High-strength inner layer; 15. Transition intermediate layer; 16. High-insulation outer layer; 2. Steel head; 21. Threaded hole; 22. Cap ring; 23. Gradient screw; 231. First gradient; 232. Second gradient; 233. Third gradient; 234. Second transition conical surface; 235. Micro-spiral groove; 3. Steel cap; 31. Groove; 32. Slot; 33. First bolt; 4. Steel foot; 41. Second bolt. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention discloses a high-strength alumina suspension insulator for rectifiers and its manufacturing process.

[0025] Example 1: A high-strength alumina suspension insulator for rectifiers, according to the attached... Figures 1-9 As shown, it includes a ceramic body 1, a steel head 2, a steel cap 3, and a steel foot 4.

[0026] Furthermore, ceramic heads 11 are provided at both the upper and lower ends of the ceramic body 1, and an umbrella body 12 is provided on the outer side of the ceramic body 1. The umbrella body 12 includes an outer umbrella 121 and an inner umbrella 122. The diameter of the outer umbrella 121 is larger than that of the inner umbrella 122, and the outer umbrella 121 and the inner umbrella 122 are staggered. In this embodiment, the outer umbrella 121 and the inner umbrella 122 are alternately arranged along the axial direction, with a total of 5 outer umbrellas and 4 inner umbrellas. The staggered distribution design of the outer and inner umbrellas increases the creepage distance of the insulator and effectively improves the anti-pollution flashover capability. At the same time, the staggered structure is conducive to the natural rinsing of rainwater and reduces the accumulation of dirt, which is particularly suitable for outdoor rectifier station environments.

[0027] Furthermore, an inner hole 13 is formed on the inner side of the ceramic head 11. The inner hole 13 has a three-stage stepped structure along the axial direction of the ceramic body 1, and a conical transition surface is provided between the steps. Specifically, the inner hole 13 includes a primary hole 131, a secondary hole 132, and a tertiary hole 133. The inner diameter of the primary hole 131 is larger than the inner diameter of the secondary hole 132, which is larger than the inner diameter of the tertiary hole 133. In this embodiment, a first transition conical surface 134 is provided between the primary hole 131 and the secondary hole 132, and between the secondary hole 132 and the tertiary hole 133. When the steel head 2 is subjected to axial tensile force, the tensile force is transmitted to the wall surface of the inner hole 13 of the ceramic body 1 through the adhesive. In the traditional cylindrical hole structure, the stress is concentrated at the edge of the hole, resulting in high peak stress, which easily leads to cracking of the ceramic body 1. The three-stage stepped structure of the present invention disperses the tensile force to three hole segments with different diameters, and each conical transition surface further disperses the stress along the axial direction, significantly reducing the peak stress.

[0028] Furthermore, the ceramic body 1 adopts a composite gradient structure design, consisting of three layers from the inside out. Radially from the inside out, it includes a high-strength inner layer 14, a transition intermediate layer 15, and a high-insulation outer layer 16. The high-strength inner layer 14 has an alumina content of 78% and contains 4% zirconium oxide toughening agent, giving it high strength and high toughness. The transition intermediate layer 15 has an alumina content of 68%. The alumina content of the transition intermediate layer 15 is higher than that of the high-insulation outer layer 16 but lower than that of the high-strength inner layer 14, achieving a smooth transition in composition and performance and avoiding interface stress concentration. The high-insulation outer layer 16 has an alumina content of 58% and contains 3% mica powder to improve surface insulation performance. Inner holes 13 are formed on the inner sides of both ends of the high-strength inner layer 14, and the umbrella body 12 is connected to the outer side of the high-insulation outer layer 16 and uses the same material as the high-insulation outer layer 16. When the insulator is under stress, the maximum tensile stress occurs inside the ceramic body 1 near the steel head 2, while the outer surface mainly bears the insulation function. The high-strength inner layer 14 imparts high strength and high toughness to the ceramic body through high alumina content and zirconium oxide toughening; the high-insulation outer layer 16 improves the surface insulation performance by appropriately reducing the alumina content and adding mica powder; the transition intermediate layer 15 achieves a smooth transition of components and properties, avoiding stress concentration at the interface.

[0029] Furthermore, two sets of steel heads 2 are provided, located at the upper and lower ends of the ceramic body 1, respectively. A threaded hole 21 is provided at the top of the steel head 2, and a cover ring 22 is fixedly connected to the outside of the steel head 2, fitting onto the outside of the ceramic head 11. The inner diameter of the cover ring 22 matches the outer diameter of the ceramic head 11, and a gap is left between the cover ring 22 and the ceramic head 11 after fitting, facilitating assembly while limiting the radial expansion of the ceramic head. A gradient screw 23 is connected to the bottom of the steel head 2, and the gradient screw 23 is provided with a first gradient 231, a second gradient 232, and a third gradient 233. The diameter of the first gradient 231 matches the diameter of the primary hole 131; the diameter of the second gradient 232 matches the diameter of the secondary hole 132; and the diameter of the third gradient 233 matches the diameter of the tertiary hole 133. A second transition conical surface 234 is provided between the first gradient 231 and the second gradient 232 and the third gradient 233. The cone angle of the second transition conical surface 234 matches the cone angle of the first transition conical surface 134. Micro-helical grooves 235 are formed on the outer sides of the first gradient 231, the second gradient 232, and the third gradient 233. The gradient screw 23 is adapted to the inner hole 13 and inserted into the inner side of the inner hole 13. A modified cement adhesive is filled between the gradient screw 23 and the inner hole 13. After the modified cement adhesive cures, it forms a mechanically interlocked structure with the micro-helical grooves 235, creating a threaded connection. The three-stage gradient structure of the gradient screw 23 precisely matches the three-stage stepped structure of the inner hole of the ceramic body, forming a fitting gap for filling with the modified cement adhesive. The design of the micro-helical grooves allows the adhesive to form a mechanically interlocked structure with the grooves after curing, similar to the principle of a threaded connection, significantly improving the bonding strength and pull-out resistance between the steel head and the ceramic body. The cap ring is fitted onto the outside of the ceramic head, further restricting the radial expansion of the ceramic head and enhancing the overall structural stability.

[0030] Specifically, the steel cap 3 is inserted into the inner side of one set of steel heads 2. The outer side of the steel cap 3 has a slot 31, and the inner side has a groove 32. A first bolt 33 is connected to the bottom of the steel cap 3, and the first bolt 33 is inserted into the threaded hole 21 of the upper set of steel heads 2. The first bolt 33 and the threaded hole 21 are connected by threads, and after connection, they are spot-welded to ensure reliable connection. The steel foot 4 is inserted into the inner side of another set of steel heads 2. The steel foot 4 is compatible with the groove 32 on the inner side of the steel cap 3, and can be snapped into the groove 32 through the slot 31. Specifically, the lower end of the steel foot 4 is provided with a snap-fit ​​connector that matches the groove 32. The snap-fit ​​connector has a T-shaped structure, and after being inserted from the slot 31, it can be pulled into the groove 32 to achieve quick connection. A second bolt 41 is connected to the top of the steel foot 4, and the second bolt 41 is inserted into the threaded hole 21 of the lower set of steel heads 2, and is also connected by threads and then spot-welded to secure it. The snap-fit ​​structure between the steel cap and the steel foot enables rapid series connection between insulators. When multiple insulators need to be connected in series, the steel foot of the previous insulator is simply snapped into the slot of the steel cap of the next insulator. The slot facilitates the insertion and removal of the steel foot, and the slot ensures the stability of the connection. The first and second bolts respectively mate with the threaded holes of the upper and lower sets of steel heads, achieving a reliable connection between the steel cap, steel foot, and ceramic body.

[0031] Example 2: A manufacturing process for a high-strength alumina suspension insulator for rectifiers, comprising the following steps: Step 1: Ball milling treatment A two-step ball milling process was employed: Step 1: The auxiliary materials were added to a planetary ball mill at a ball-to-material ratio of 3:1, using alumina balls as the milling media. The milling speed was 300 rpm for 4 hours, coarsely grinding to a particle size of 10–15 μm. Step 2: Surface-modified nano-alumina was added, and ball milling continued for 2 hours at 250 rpm, finely grinding to a particle size of 2–5 μm. This two-step milling process ensured uniform dispersion of the nano-components and prevented nanoparticle agglomeration. After milling, the slurry was sieved through a 200-mesh sieve, magnetically separated to remove iron, and the slurry moisture content was controlled at 32%.

[0032] Step 2: Gradient Molding Three types of slurry were prepared: a high-strength inner layer slurry, a transitional intermediate layer slurry, and a high-insulation outer layer slurry.

[0033] A layered casting process is employed: First, a high-strength inner layer of slurry is poured into a plaster mold, allowed to stand for 15 minutes, and then the excess slurry is poured out. Next, a transitional intermediate layer of slurry is poured, allowed to stand for 12 minutes, and then the excess slurry is poured out. Finally, a high-insulation outer layer of slurry is poured, and allowed to stand for 20 minutes until the green body reaches the required demolding hardness. After each layer of slurry is poured, the mold is placed in a gradient magnetic field treatment device, and a directional magnetic field with a strength of 1.0T is applied along the radial direction of the ceramic body for 10 minutes. This magnetic field treatment aligns the c-axis of the alumina grains radially, improving radial mechanical properties. Tests show that the magnetic field treatment increases the flexural strength by approximately 12%. After demolding, a wet ceramic green body is obtained.

[0034] Step 3: Drying and trimming the blank The wet blanks were placed in a drying chamber at a controlled temperature of 40℃ and relative humidity of 60% for 24 hours. Once the moisture content of the blanks dropped below 8%, the temperature was increased to 80℃ and drying continued for another 12 hours, controlling the final moisture content to 1.8%. A CNC trimming machine was then used to trim the dried blanks, machining a three-tiered internal hole structure and a first transition conical surface according to the design dimensions, thus refining the umbrella-shaped outline. After trimming, 800-grit sandpaper was used to roughen the surface of the inner hole of the ceramic head, enhancing its adhesion to the adhesive.

[0035] Step 4: Glazing The head and umbrella sections are glazed separately. For the bonding glaze application, the entire smooth body is glazed using an immersion method, with an immersion time of 5 seconds and a glaze thickness controlled at 100μm. After glazing, it is dried at 80℃ for 30 minutes.

[0036] For the head area treatment, apply a 3% CMC (carboxymethyl cellulose) aqueous solution to the head area. After application, a protective film is formed to prevent water from the subsequent glaze from seeping into the interior of the blank.

[0037] Apply a barrier glaze to the head area using a head glazing machine, with a glaze thickness of 120μm. After glazing, dry at 80℃ for 30 minutes.

[0038] For the head, the functional glaze is applied by spraying a sol-gel onto the surface of the head's barrier glaze layer to a thickness of 80 μm. After application, it is dried at 80°C for 30 minutes.

[0039] The umbrella surface is glazed using an umbrella surface glazing machine, with a glaze thickness of 150μm. After glazing, it is dried at 80℃ for 30 minutes.

[0040] Step 5: Sintering treatment The glazed body is then placed in a high-temperature shuttle kiln for sintering. Heating stage: The temperature is increased from room temperature to 500℃ at a rate of 3℃ / min, and held for 1 hour to remove wax; then increased to 1000℃ at a rate of 2℃ / min; and then increased to 1550℃ at a rate of 1.5℃ / min. Holding stage: The temperature is held at 1550℃ for 2.5 hours. Cooling stage: The temperature is reduced to 800℃ at a rate of 3℃ / min, and then cooled to room temperature in the furnace. After sintering, alumina ceramic insulator body is obtained.

[0041] Step Six: Assembly Processing For the steel head pretreatment, the material of steel head 2 is 35CrMo alloy steel, and the surface is galvanized for rust prevention. Micro-helical grooves 235 are machined on the surface of the gradient screw 23 of the steel head, with a pitch of 0.5mm and a groove depth of 0.25mm. The grooves are formed using a roll forming process. The surface roughness Ra after machining is controlled at 1.6μm.

[0042] For assembly, insert the gradient screw 23 of the steel head 2 into the inner hole 13 of the ceramic body 1, forming a 0.5mm gap between the gradient screw 23 and the inner hole 13. Inject modified cement adhesive into this gap, ensuring that the adhesive fully fills the micro-spiral groove 235. Apply an axial preload of 1.5kN using a press to ensure a tight fit between the steel head and the ceramic body, while the cover ring 22 is fitted onto the outside of the ceramic head 11.

[0043] Curing and heat treatment: Curing at room temperature for 48 hours to fully solidify the modified cement adhesive. Then, place it in an oven for heat treatment at 180℃ for 2 hours to eliminate assembly internal stress and further harden the adhesive.

[0044] For assembling the steel cap and steel foot, screw the first bolt 33 of the steel cap 3 into the threaded hole 21 of the upper steel head 2, tighten it, and then spot weld it in place. Screw the second bolt 41 of the steel foot 4 into the threaded hole 21 of the lower steel head 2, tighten it, and then spot weld it in place.

[0045] After assembly, electrical and mechanical performance tests are conducted, and the products are packaged and stored after passing the tests.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0047] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength alumina suspension insulator for rectifiers, characterized in that, include: The ceramic body (1) has ceramic heads (11) at both ends. The ceramic heads (11) have an inner hole (13) on the inner side. The inner hole (13) is designed in a three-level stepped structure along the axial direction of the ceramic body (1), and there is a conical transition between the steps. The ceramic body (1) adopts a composite gradient structure design, which consists of a high-strength inner layer (14), a transition intermediate layer (15), and a high-insulation outer layer (16) from the inside to the outside. The steel head (2) is provided in two sets. The steel head (2) is inserted into the inner side of the inner hole (13). The outer side of the steel head (2) is provided with a micro spiral groove (235). A steel cap (3) is inserted into the inside of one set of steel heads (2); a steel foot (4) is inserted into the inside of another set of steel heads (2).

2. The high-strength alumina suspension insulator for rectifiers according to claim 1, characterized in that, The ceramic body (1) is provided with an umbrella body (12) on the outside. The umbrella body (12) includes an outer umbrella (121) and an inner umbrella (122). The diameter of the outer umbrella (121) is larger than that of the inner umbrella (122). The outer umbrella (121) and the inner umbrella (122) are staggered.

3. A high-strength alumina suspension insulator for rectifiers according to claim 1, characterized in that, The inner hole (13) includes a primary hole (131), a secondary hole (132) and a tertiary hole (133). The inner diameter of the primary hole (131) is larger than the inner diameter of the secondary hole (132) and the inner diameter of the tertiary hole (133). A first transition conical surface (134) is provided between the primary hole (131) and the secondary hole (132) and between the secondary hole (132) and the tertiary hole (133).

4. A high-strength alumina suspension insulator for rectifiers according to claim 2, characterized in that, The composite gradient structure of the ceramic body (1) includes, in the radial direction from the inside out, a high-strength inner layer (14), a transition intermediate layer (15), and a high-insulation outer layer (16). The high-strength inner layer (14) has a higher alumina content than the transition intermediate layer (15) and is reinforced with zirconia. The transition intermediate layer (15) has a higher alumina content than the high-insulation outer layer (16). The high-insulation outer layer (16) is reinforced with mica powder. The inner holes (13) are opened on the inner sides of both ends of the high-strength inner layer (14). The umbrella body (12) is connected to the outer side of the high-insulation outer layer (16) and is made of the same material as the high-insulation outer layer (16).

5. A high-strength alumina suspension insulator for rectifiers according to claim 1, characterized in that, The top of the steel head (2) is provided with a threaded hole (21). A cover ring (22) is fixedly connected to the outside of the steel head (2). The cover ring (22) is sleeved on the outside of the ceramic head (11). The bottom of the steel head (2) is connected to a gradient screw (23). The gradient screw (23) is provided with a first gradient (231), a second gradient (232) and a third gradient (233). The first gradient (231) and the second gradient (232) are connected to the second gradient (232) and the third gradient (233). 3) A second transition conical surface (234) is provided between them. Micro-spiral grooves (235) are opened on the outer side of the first gradient (231), the second gradient (232) and the third gradient (233). The gradient screw (23) is adapted to the inner hole (13) and is inserted into the inner side of the inner hole (13). The gradient screw (23) and the inner hole (13) are filled with modified cement adhesive. After the modified cement adhesive is cured, it forms a mechanical interlocking structure with the micro-spiral groove (235) for threaded connection.

6. A high-strength alumina suspension insulator for rectifiers according to claim 1, characterized in that, The steel cap (3) has a slot (31) on the outside and a slot (32) on the inside. The bottom of the steel cap (3) is connected to a first bolt (33), which is inserted into the threaded hole (21) of the upper set of steel heads (2).

7. A high-strength alumina suspension insulator for rectifiers according to claim 1, characterized in that, The steel foot (4) is adapted to the slot (32) inside the steel cap (3) and can be engaged in the slot (32) through the slot (31). The top of the steel foot (4) is connected to a second bolt (41), which is inserted into the threaded hole (21) of the lower set of steel heads (2).

8. A manufacturing process for a high-strength alumina suspension insulator for rectifiers as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Ball milling: The raw material is ball milled to control the fineness of the slurry; Step 2, Gradient molding: Using a layered casting molding process, the high-strength inner layer (14) slurry, the transition intermediate layer (15) slurry and the high-insulation outer layer (16) slurry are poured in sequence; Step 3, Drying and trimming: The formed blank is dried and then trimmed to obtain a smooth blank; Step 4: Glazing treatment: Glaze the unglazed body; Step 5, sintering treatment: The glazed body is placed in a high-temperature kiln for sintering to obtain alumina ceramic insulator body; Step 6, Assembly: Assemble the steel head (2) into the inner hole (13) of the ceramic body (1). Fill the space between the gradient screw (23) of the steel head (2) and the inner hole (13) of the ceramic body (1) with modified cement adhesive. After assembly, apply axial preload and perform curing and heat treatment.

Images