A porcelain sleeve forming process

Abstract

The application discloses a porcelain sleeve forming process and belongs to the technical field of porcelain sleeve forming. The process comprises the following steps: aging to-be-formed clay for more than 120 hours; performing vacuum extrusion operation on the clay to obtain a blank; performing electric dry treatment on the blank; performing blank repairing and forming on the electric dry blank, and then performing natural dry and drying to obtain a dry blank; performing glazing on the dry blank to obtain a glazed blank; performing high-temperature baking on the glazed blank after treatment to obtain a porcelain piece; and performing overall grinding and other post-treatment on the porcelain piece after inorganic bonding, so that the forming process of the porcelain sleeve is finally completed. In the forming process, the aging and vacuum extrusion clay refining process is used to ensure the uniformity of the internal organization of the clay section, the structural stability and the uniformity and rationality of the clay particles. The vertical electric dry treatment and vertical glazing method are used to solve the problems of clay turning and glazing difficulty of the dry blank. The porcelain sleeve prepared by the application has excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of ceramic sleeve forming technology, and specifically relates to a ceramic sleeve forming process. Background Technology

[0002] Insulators are widely used in power systems and electrical equipment to mechanically connect conductors at different potentials while electrically insulating them. Among them, porcelain bushings (hollow porcelain insulators) are key components of high-voltage capacitor bushings. The forming process of porcelain bushings mainly includes extrusion blanks, natural air drying, CNC trimming, hot air drying, glazing, firing, cutting, grinding, and testing.

[0003] Chinese patent CN101289311B discloses a wet production process for a white glaze integrally molded porcelain bushing for a 220 kV sulfur hexafluoride circuit breaker. The production process in this application was previously developed and established by our company. With the development of ultra-high voltage power transmission and transformation, the traditional porcelain bushing production process has many problems. For example, cracks are prone to occur on the surface of the blank during the extrusion process; the blank is prone to breakage and collapse during the natural air drying process; and the dry blank is prone to transverse breakage during the glazing process. Therefore, it is necessary to improve the existing porcelain bushing molding process to increase the yield of the extrusion, air drying and glazing processes, thereby improving the mechanical properties of the final porcelain bushing. Summary of the Invention

[0004] The purpose of this invention is to provide a ceramic sleeve molding process to improve the mechanical properties of ceramic sleeves.

[0005] The objective of this invention can be achieved through the following technical solutions: A ceramic sleeve forming process includes the following steps: S1. Select clay material with a moisture content of 17.0%-17.5% to be molded, and age it for more than 120 hours before use; S2. The above-mentioned clay material is subjected to vacuum extrusion using a clay mixing machine. The vacuum degree during vacuum extrusion is ≥0.097Mpa, and a blank is obtained. The outer diameter of the blank is 840mm-1500mm; the inner diameter of the blank is 360mm-600mm; and the length is 2400mm-3500mm. S3. The blank is subjected to electro-drying treatment, and the moisture content of the blank after electro-drying is 16.0%-17.0%; S4. Trim and shape the blank after it has been air-dried by electric air. Then, place the blank on a tray and air-dry it naturally for 10-15 days. Then, send it into the drying room to dry. After drying, you will get the dry blank. S5. Use a hoisting tool to suspend the dry blank and immerse it in a glaze vat filled with brown glaze. The immersion time is 6-10 seconds. After glazing, the glazed blank is obtained. S6. After the glazed blanks are trimmed, sanded, loaded into the kiln vertically, and fired at high temperature, 10 sections of porcelain are obtained. The 10 sections of porcelain are then joined together by inorganic bonding, and then ground as a whole and cured by flange glue. After passing the inspection, they can be shipped out of the factory, completing the forming process of the porcelain sleeve.

[0006] Furthermore, the blank described in step S2 comprises 10 sections of clay of different sizes, specifically: Section 1: Outer diameter 840mm, inner diameter 360mm, length 3500mm; Section 2: Outer diameter 840mm, inner diameter 360mm, length 3400mm; Section 3: Outer diameter 915mm, inner diameter 360mm, length 2750mm; Section 4: Outer diameter 1100mm, inner diameter 480mm, length 2600mm; Section 5: Outer diameter 1200mm, inner diameter 480mm, length 2450mm; Section 6: ... Section 1: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 2: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 3: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 4: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 5: Outer diameter 1500mm, inner diameter 600mm, length 2400mm.

[0007] Furthermore, the electro-drying process described in step S3 includes horizontal electro-drying and vertical electro-drying, wherein the mud sections 1-4 are dried horizontally and the mud sections 5-10 are dried vertically. The horizontal electro-drying process is as follows: the two ends of the mud section are connected to the electrodes with copper wire mesh. After wiring, the mud section is horizontally dried for 6-8 hours. During the electro-drying period, the mud section is rotated 90° every 4 hours, rotated 360° in the same direction, and then rotated back. The vertical electro-drying process involves placing a mud cake ≥200mm high at the lower end of the mud section, and then laying a copper wire mesh on top of the mud section for electro-drying; the vertical drying time of the mud section is ≥144 hours, and the initial current density is 0.32-0.37mA / cm². 2 The termination current density is 1.8-2.2 mA / cm². 2 .

[0008] Furthermore, the drying room temperature in step S4 is set to 100°C and the drying time is 216 hours.

[0009] The beneficial effects of this invention are: 1. In the molding process of the present invention, the clay material to be molded with appropriate moisture content is first selected, and the uniformity of the internal structure, the stability of the structure, and the uniformity of the clay particles are ensured through aging and vacuum extrusion refining processes.

[0010] 2 In the molding process of the present invention, vertical electric anodizing is used to process large-diameter mud sections, which solves the problem of mud turning over in large-diameter mud sections. At the same time, vertical electric anodizing can promote the uniform distribution of moisture in large-diameter mud sections and can shrink synchronously, making the internal structure of the mud section more stable.

[0011] 3. In the molding process of this invention, the vertical dip glazing method is adopted, which solves the problem of difficulty in glazing large-sized dry blanks and greatly reduces the probability of breakage when the dry blanks lose water absorption strength. Compared with the traditional method of "horizontal hanging and oblique dipping for glazing", the vertical dip glazing method is less prone to breakage. At the same time, the vertical dip glazing method has stronger stability and reliability.

[0012] 4. In the molding process of the present invention, the final ceramic sleeve produced has excellent mechanical properties (no cracking or other phenomena occur under internal pressure of 4MPa; the maximum bending strength is 21.26MPa). Detailed Implementation

[0013] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] This invention relates to a ceramic sleeve forming process, comprising the following steps: S1. The electric porcelain production formula adopts a pure porcelain test rod with a bending strength of over 200MPa, which is more than 15% higher than the current 500kV GIS porcelain bushing electric porcelain formula. S2. The raw materials of the above formula are ball-milled using a two-stage ball milling process to obtain mud with the best particle size distribution. S3. Select clay materials with a moisture content of 17.0%-17.5% and allow them to age for more than 120 hours; S4. The above-mentioned mud material is vacuum extruded using a specially designed mud-extrusion sleeve on a φ1000mm all-stainless steel mud-mixing machine with automatic cooling. The vacuum degree during vacuum extrusion is ≥0.097Mpa, resulting in a blank. The outer diameter of the blank is 840mm-1500mm; the inner diameter is 360mm-600mm; and the length is 2400mm-3500mm. The blank consists of 10 mud sections of different sizes. Specifically, the first mud section has an outer diameter of 840mm, an inner diameter of 360mm, and a length of 3500mm; the second mud section has an outer diameter of 840mm, an inner diameter of 360mm, and a length of 3400mm; the third mud section has an outer diameter of 915mm, an inner diameter of 360mm, and a length of 275mm. 0mm; Section 4: Outer diameter 1100mm, inner diameter 480mm, length 2600mm; Section 5: Outer diameter 1200mm, inner diameter 480mm, length 2450mm; Section 6: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 7: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 8: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 9: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 10: Outer diameter 1500mm, inner diameter 600mm, length 2400mm; S5. All 10 clay sections are electro-dried. Sections 1-4 are dried horizontally, with copper wire mesh connected to electrodes at both ends. After wiring, the sections are dried horizontally for 6-8 hours. During electro-driing, the sections are rotated 90° every 4 hours (after power is cut off), rotated 360° in the same direction, and then rotated back to ensure more even moisture distribution. Sections 5-10 are dried vertically (weighing 6632kg-7834kg). For vertical electro-driing, a clay cake ≥200mm high is placed under the bottom of each section, and a copper wire mesh is laid on top. Vertical electro-driing is superior to horizontal electro-driing because it saves manpower, reduces weight, eliminates the need for rotating sections, and ensures more even moisture distribution. The vertical drying time is ≥144 hours, with an initial current density of 0.32-0.37mA / cm². 2 The termination current density is 1.8-2.2 mA / cm². 2， After electro-drying, the moisture content of the blank is 16.0%-17.0%, and the pass rate of the dried blank is over 80%. S6. A fully automatic internal and external CNC blank trimming machine with a working height of 4.2m, capable of trimming outer diameters of 0.84-1.550m, inner diameters of 0.30m-1.0m, and a load capacity of 10t, is used to trim and shape blanks that have been dried by electric drying. S7. Because the umbrella of this product has a wet extension of 144mm and a large blank (maximum umbrella diameter of 1368mm), the normal drying curve will cause uneven moisture shrinkage during drying, resulting in defects such as umbrella falling off. Therefore, a special blank air drying process is formulated. After the blank is repaired, it is placed on a tray for natural air drying for 10-15 days, and then sent into an automatic hot air circulating drying room for drying. After drying, the dry blank is obtained. The drying room temperature is set at 100℃ and the drying time is 216h. S8. Dry-repair the blanks and use lifting fixtures to stand them upright. Use lifting fixtures of different sizes to insert into the inner holes of various types of blanks. Then wrap the lifting heads at both ends and the tail of the base with sponge and put them into the fixtures. Place lifting rings at the upper end of the iron pipe and use a crane and ropes to lift the iron pipe so that the blank is suspended in the air. Then immerse the lifted blank into a glaze vat filled with brown glaze for 6-10 seconds. When the blank is put into the vat, gently shake it by hand. After the glazing is completed, the glazed blank is obtained. S9. After finishing the surface of the glazed blank, a sanding process is performed. Then, the blank is loaded into the kiln vertically and fired at high temperature to obtain 10 sections of porcelain. After each section is removed from the kiln, the qualified sections are cut, ground, and matched. Then, the 10 sections are joined together by inorganic bonding, followed by overall grinding, flange gluing, and curing. After passing inspection, the blank is ready to be shipped out, completing the forming process of the porcelain sleeve.

[0015] Examples 1, 2, and 3 are specific embodiments of the above content.

[0016] Table 1 below details the specific process parameters for Examples 1, 2, and 3. The mechanical properties of the ceramic sleeves produced in Examples 1-3 were also tested. The testing process is as follows, and the test results are shown in Table 1 below. Pressure resistance test: Take the porcelain sleeves produced in Examples 1, 2 and 3, fill the porcelain sleeves with water, connect both ends of the porcelain sleeves to the hydraulic pump, start the hydraulic pump, and increase the liquid pressure inside the porcelain sleeves to 4MPa at a constant pressure increase rate of 2MPa / min. Maintain the constant pressure for 1min, and record whether the porcelain sleeves produced in each example crack or other phenomena occur.

[0017] Bending strength: The porcelain sleeves produced in Examples 1, 2 and 3 were tested for bending strength using a testing machine. The test was repeated for three groups, and the average value was taken.

[0018] Table 1

[0019] As can be seen from Table 1, the ceramic sleeves produced in Examples 1-3 have excellent mechanical properties. It should be noted that, in this document, terms such as “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 process, method, article, or apparatus.

[0020] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A ceramic sleeve forming process, characterized in that, Includes the following steps: S1. Select clay material with a moisture content of 17.0%-17.5% to be molded, and age it for more than 120 hours before use; S2. The above-mentioned clay material is subjected to vacuum extrusion using a clay mixing machine. The vacuum degree during vacuum extrusion is ≥0.097Mpa, and a blank is obtained. The outer diameter of the blank is 840mm-1500mm; the inner diameter of the blank is 360mm-600mm; and the length is 2400mm-3500mm. S3. The blank is subjected to electro-drying treatment, and the moisture content of the blank after electro-drying is 16.0%-17.0%; S4. Trim and shape the blank after it has been air-dried by electric air. Then, place the blank on a tray and air-dry it naturally for 10-15 days. Then, send it into the drying room to dry. After drying, you will get the dry blank. S5. Use a hoisting tool to suspend the dry blank and immerse it in a glaze vat filled with brown glaze. The immersion time is 6-10 seconds. After glazing, the glazed blank is obtained. S6. After the glazed blanks are trimmed, sanded, loaded into the kiln vertically, and fired at high temperature, 10 sections of porcelain are obtained. The 10 sections of porcelain are then joined together by inorganic bonding, and then ground as a whole and cured by flange glue. After passing the inspection, they can be shipped out of the factory, completing the forming process of the porcelain sleeve. The blank mentioned in step S2 includes 10 sections of clay of different sizes, specifically: Section 1: Outer diameter 840mm, inner diameter 360mm, length 3500mm; Section 2: Outer diameter 840mm, inner diameter 360mm, length 3400mm; Section 3: Outer diameter 915mm, inner diameter 360mm, length 2750mm; Section 4: Outer diameter 1100mm, inner diameter 480mm, length 2600mm; Section 5: Outer diameter 1200mm, inner diameter 480mm, length 2450mm; Section 6: ... Section 1: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 2: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 3: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 4: Outer diameter 1400mm, inner diameter 600mm, length 2400mm; Section 5: Outer diameter 1500mm, inner diameter 600mm, length 2400mm; The electro-drying process described in step S3 includes horizontal electro-drying and vertical electro-drying. Specifically, the first to fourth mud sections are dried horizontally, while the fifth to tenth mud sections are dried vertically. The horizontal electro-drying process is as follows: the two ends of the mud section are connected to the electrodes with copper wire mesh. After the connection is made, the mud section is horizontally dried for 6-8 hours. During the electro-drying period, the mud section is rotated 90° every 4 hours, rotated 360° in the same direction, and then rotated back. The vertical electro-drying process involves placing a mud cake ≥200mm high at the lower end of the mud section, and then laying a copper wire mesh on top of the mud section for electro-drying; the vertical drying time of the mud section is ≥144 hours, and the initial current density is 0.32-0.37mA / cm². 2 The termination current density is 1.8-2.2 mA / cm². 2 .

2. The ceramic sleeve forming process according to claim 1, characterized in that, In step S4, the drying room temperature is set to 100℃ and the drying time is 216h.

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