CN101786863A - Production method of large-size insulator of 95 % ceramics - Google Patents

Abstract

A kind of production method of 95 porcelain large porcelain sets, it is characterized in that it comprises the following steps: a, raw material preparation; b, ball milling; c, sieving; d, mixing and stirring; e, removing iron; ; h, grading; i, isostatic pressing; j, billet trimming; k, firing and l, grinding and polishing the porcelain sleeve obtained by firing. The invention solves the long-standing problem of low mechanical strength and easy damage caused by the use of only 50 porcelain insulators for electrostatic precipitators. The 95 porcelain large-size porcelain bushing manufactured by the invention has the advantages of high mechanical strength and large high-temperature resistance value.

Description

Production method of 95 large porcelain sets

technical field

The invention relates to a production process of a porcelain sleeve, in particular to a production method of a large size 95 porcelain sleeve, specifically a production method of a 95 porcelain large porcelain sleeve.

Background technique

As we all know, for a long time, most of the large porcelain sleeve insulators used for the insulation support of the cathode system of high-voltage electrostatic precipitators are processed and produced with 50 porcelain. After long-term practice, it is generally believed that the mechanical strength and high temperature resistance of 50 porcelain are poor. It is difficult to meet the needs of production, so it is urgent to find an upgraded replacement product. 95 porcelain has good high-temperature insulation and sufficient mechanical strength, but since the main raw material of 95 porcelain is Al ₂ O ₃ , alumina is a ridge material, and it is difficult to form; the firing temperature is high. Especially in the production of large-scale hollow thin-walled products, the process is very difficult, and deformation and bursting losses often occur.

Contents of the invention

The purpose of this invention is to solve the problem that 95 porcelain cannot be popularized and applied in large-scale porcelain sleeve insulators due to the lack of corresponding manufacturing methods, and to provide a production method of 95 porcelain large porcelain sleeves on the basis of successful trial production.

Technical scheme of the present invention is:

A kind of production method of 95 porcelain big porcelain sets, it is characterized in that it comprises the following steps:

a. Raw material preparation: the weight percentage of each component is: alumina 94-96%, calcium carbonate 1.5-2.5%, quartz sand 2-4%;

b, ball milling: put the above-mentioned ingredients in a ball mill to pulverize and ball mill to a powder whose particle size is less than 360 mesh;

c, sieving: the powder material that above-mentioned ball milling obtains is sieved with 360 mesh sieves, removes particle size greater than 360 mesh particles;

d. Mixing and stirring: add 5-6% by weight of the binder and an appropriate amount of water to the powder obtained by sieving the above to obtain a slurry;

e, iron removal: make the slurry obtained above pass through an iron absorber to remove iron components therein;

f. Granulation: Send the above-mentioned slurry from which iron components have been removed into a granulation tower to granulate by spray drying to obtain granular raw materials. Internal pressure -100～200Pa;

g. Classification: Segregate the granular raw materials obtained from the prilling tower. The classification standard is particle size ≥ 0.12mm (grade A), particle size ≤ 0.015mm (grade C) and particle size between 0.015-0.12mm (grade B) )between;

h. Grading: Mix 75-85% of A-grade granular raw materials, 7-13% of B-grade granular raw materials, and 7-13% of C-grade granular raw materials to obtain static pressure raw materials;

i, isostatic pressing forming: the static pressing raw material that above-mentioned gradation obtains is placed in the mold of isostatic pressing forming machine, and the control pressure is between 130MPa-150MPa, and hold the pressure for 3-10 minutes and then release the pressure and take out to obtain the blank;

j. Blank trimming: use the processing machine tool to machine the obtained blank to make the shape and size consistent with the design value;

k. Firing: Send the blanks after trimming above into a roasting furnace for firing, control the firing temperature between 1550-1700°C, control the temperature fluctuation value ±10°C, hold for 1-2 hours, and burn Natural cooling after completion;

l. Grinding and polishing the porcelain sleeve obtained from the above-mentioned firing.

In order to prevent conductive breakdown caused by the iron component in the raw material, the iron removal operation can be continuously performed twice during the iron removal process, even if the slurry circulates through the iron remover twice.

Beneficial effects of the present invention:

After a large number of experiments, the present invention has explored a set of production technology of 95 porcelain large-scale hollow porcelain bushings, which has solved the problems of low mechanical strength and easy damage that have existed for a long time since electrostatic precipitators can only use 50 porcelain insulators. The 95-porcelain large-size porcelain sleeve invented and manufactured has the advantages of high mechanical strength and large high-temperature resistance value.

Description of drawings

Fig. 1 is a specific process flow diagram of an advantageous embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1.

A production method of 95 porcelain large porcelain sets, it comprises the following steps:.

a. Raw material preparation: the weight percentage of each component is: alumina 94-96%, calcium carbonate 1.5-2.5%, quartz sand 2-4%; the specific ingredients are:

(1) 94 kg of alumina, 1.5 kg of calcium carbonate, and 2 kg of quartz sand;

(2) 96 kilograms of alumina, 2.5 kilograms of calcium carbonate, 4 kilograms of quartz sand;

(3) 95 kg of alumina, 2 kg of calcium carbonate, and 3 kg of quartz sand;

Any one of the above three can be selected;

b, ball milling: put the above-mentioned ingredients in a ball mill to pulverize and ball mill to a powder whose particle size is less than 360 mesh;

c, sieving: the powder material that above-mentioned ball milling obtains is sieved with 360 mesh sieves, removes particle size greater than 360 mesh particles;

d. Mixing and stirring: the above-mentioned sieved powder is added with a binder (polyvinyl alcohol can be used) of 5-6% by weight and an appropriate amount of water for stirring to obtain a slurry. The viscosity of the slurry can be passed through Subsequent iron suction machine is appropriate;

E, iron removal: make the above-mentioned obtained slurry remove the iron content therein through an iron absorber (can adopt the same iron absorber as the prior art);

f, granulation: send the above-mentioned slurry from which the iron content has been removed into a granulation tower (similar to the granulation tower used in the chemical fertilizer industry) and use the spray drying method to granulate to obtain granular raw materials. The temperature in the prilling tower is not less than 400°C, and the pressure inside the tower: -100～200Pa;

g. Classification: The granular raw materials obtained from the prilling tower are stored in poles. The classification standard is particle size ≥ 0.12mm (grade A), particle size ≤ 0.015mm (grade C) and particle size between 0.015-0.12mm (grade B) between levels);

h, grading: get A-grade granular raw material 75-85% (weight percentage, the same below), B-grade granular raw material 7-13%, C-grade granular raw material 7-13% and mix to obtain static pressure raw material; The total weight can be calculated according to the size of the final formed product, plus an appropriate amount of trimming allowance as the basis for grading calculation weight;

i, isostatic pressing forming: the static pressing raw material that above-mentioned grading obtains is placed in the mold of isostatic pressing forming machine, and the control pressure is between 130MPa-150MPa, and pressure-holding 3-10 minutes is released and taken out to obtain blank, The pressure relief operation should be carried out according to the manual of the isostatic pressing machine;

j. Blank trimming: use the processing machine tool to machine the obtained blank to make the shape and size consistent with the design value;

k. Firing: Send the blanks after trimming above into a roasting furnace for firing, control the firing temperature between 1550-1700°C, control the temperature fluctuation value ±10°C, hold for 1-2 hours, and burn Cool naturally after firing; the specific firing time can be selected and determined by referring to the relevant design manual.

l. Grinding (including cutting) and polishing the porcelain sleeves obtained from the above-mentioned firing, after passing the final inspection, they can be packaged and put into storage, waiting for shipment.

The isostatic pressing forming technology used in the present invention is a new technology developed in the 1990s. Generally, the isostatic pressing technology is more suitable for pressing cylindrical or cylindrical blanks, while defects such as damage and cracking are prone to occur when pressing conical blanks. In order to overcome this problem, when pressing the mold core of the conical large porcelain sleeve, it should be processed according to the taper required by the product. The outer mold should be as conical as possible to avoid axial slippage of the powder when pressing, which can effectively prevent cracks. .

In addition, the present invention strictly controls parameters such as the shape, particle gradation, loose bulk density, and fluidity of the granulated powder through spray drying, which also helps to improve the quality of isostatic pressing.

High-temperature firing is a key process that determines product quality, and various defects of ceramic products are often reflected through this process. When firing 95 porcelain large porcelain sleeves, the kiln temperature must be uniform. The so-called uniform kiln temperature requires that the temperature change in the kiln should be uniform in terms of time, and cannot rise and fall suddenly; in terms of space, it requires that the temperature in all parts of the kiln should be basically consistent. In other words, the heating of each part of the product must be uniform, otherwise, there will be defects such as bursting and deformation. Usually, when firing a product with a relatively small size, due to its small size, the entire product is shrouded in flames, there is no large temperature gradient in each part of the product, and the heating of each part is basically uniform, and generally there will be no quality problems. However, if the product is relatively large, it can block and shield the transmission of flame or temperature, and there will be a large temperature difference between the flame-facing surface and the back-flame surface, especially in the high-temperature shrinkage or high-temperature softening stage. , It is bound to produce deformation and cracking loss of the product. In order to avoid the loss of deformation and cracking of large porcelain sleeves, high-speed burners can be used to strengthen the agitation of the flame in the kiln, reasonably arrange the density of the kiln, and leave a suitable gap between the products to facilitate the flow of the flame and the roasting of the product. Slots are slotted on the seat to facilitate the flow of flame from the inside of the product and other measures to solve the problem.

The parts not involved in the present invention, such as the specific structure of the roasting furnace, the specific structure of the isostatic pressing machine, etc., are the same as the prior art or can be realized by using the prior art.

Claims (2)

1. A production method of 95 porcelain large porcelain sleeves is characterized in that it comprises the following steps: a. Raw material preparation: the weight percentage of each component is: alumina 94-96%, calcium carbonate 1.5-2.5%, quartz sand 2-4%; b, ball milling: put the above-mentioned ingredients in a ball mill to pulverize and ball mill to a powder whose particle size is less than 360 mesh; c, sieving: the powder material that above-mentioned ball milling obtains is sieved with 360 mesh sieves, removes particle size greater than 360 mesh particles; d. Mixing and stirring: add 5-6% by weight of the binder and an appropriate amount of water to the powder obtained by sieving the above to obtain a slurry; e, iron removal: make the slurry obtained above pass through an iron absorber to remove iron components therein; f. Granulation: Send the above-mentioned slurry from which iron components have been removed into a granulation tower to granulate by spray drying to obtain granular raw materials. Internal pressure -100～200Pa; g. Classification: Segregate the granular raw materials obtained from the prilling tower. The classification standard is particle size ≥ 0.12mm (grade A), particle size ≤ 0.015mm (grade C) and particle size between 0.015-0.12mm (grade B) )between; h. Grading: Mix 75-85% of A-grade granular raw materials, 7-13% of B-grade granular raw materials, and 7-13% of C-grade granular raw materials to obtain static pressure raw materials; i, isostatic pressing forming: the static pressing raw material that above-mentioned gradation obtains is placed in the mold of isostatic pressing forming machine, and the control pressure is between 130MPa-150MPa, and hold the pressure for 3-10 minutes and then release the pressure and take out to obtain the blank; j. Blank trimming: use the processing machine tool to machine the obtained blank to make the shape and size consistent with the design value; k. Firing: Send the blanks after trimming above into a roasting furnace for firing, control the firing temperature between 1550-1700°C, control the temperature fluctuation value ±10°C, hold for 1-2 hours, and burn Natural cooling after completion; l. Grinding and polishing the porcelain sleeve obtained from the above-mentioned firing. 2. The production method of 95 porcelain large porcelain sleeves according to claim 1, characterized in that the iron removal is carried out twice continuously.

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