A method for producing a burr-free varistor ceramic green sheet

Abstract

The present invention relates to the field of special ceramic green sheets production, and in particular to a method for producing burr-free varistor ceramic green sheets, comprising: sequentially mixing and ball-milling the raw materials of the varistor ceramic green sheets to form mixed raw material powders; introducing the mixed raw material powders into a granulation molding machine to output test mixed particles; collecting the vertical moving rate of the test mixed particles; determining a granulation adjustment method according to the vertical moving rate of the test mixed particles; actually molding the mixed raw material powders according to the granulation adjustment method to output actual mixed particles; controlling a pressing device to press the actual mixed particles according to the granulation adjustment method to form a target green sheet of a corresponding shape; and cleaning the flash to output a burr-free finished varistor ceramic green sheet. The present invention improves the production quality and production efficiency of burr-free varistor ceramic green sheets.

Description

Technical Field

[0001] The invention relates to the field of special ceramic green sheets production, and in particular to a method for producing burr-free pressure-sensitive ceramic green sheets. Background Art

[0002] In the traditional production process of varistor ceramic green sheets, flash often appears on the green sheets after forming. This is because in processes such as dry pressing, there is a certain gap between the upper and lower punches of the mold and the mold cavity. When pressure is applied to the ceramic powder to form it, part of the ceramic powder will be squeezed into these gaps, forming flash on the edge of the green sheet. If the green sheet has flash, the flash will cause the cutting accuracy to decrease when it is cut into chips of a specific size. Because the presence of flash makes the edge of the green sheet uneven, it is easy to cause the cutting tool to deviate during the cutting process, so that the size deviation of the chip exceeds the allowable range. Flash may cause adhesion between green sheets during sintering. During high-temperature sintering, the flash of adjacent green sheets contact and bond together at high temperature, which can easily cause the green sheet to break and reduce the qualified rate of the product. When preparing electrodes for green sheets, flash will affect the quality of the electrode. The irregular shape and rough surface of the flash will cause the electrode material to be unevenly distributed at the edge of the green sheet, thereby affecting the electrical properties of the varistor ceramic. As the requirements for the performance and reliability of varistor ceramics in application fields such as new energy and new power systems continue to increase, traditional flash-edged blanks can no longer meet the demand.

[0003] Chinese patent publication number CN103011799B discloses a production method of zinc oxide-based varistor ceramics sintered at a low temperature within a range. The method is characterized in that a pre-prepared perovskite-type praseodymium-based composite oxide solid solution is added to the main raw material of zinc oxide as the main dopant, and a small amount of vanadium oxide, manganese oxide or manganese carbonate, bismuth oxide, niobium oxide and the like are added as dopants; the basic molecular formula of the praseodymium-based composite oxide solid solution involved is ABO3, the crystal structure is perovskite-type, the A position is a praseodymium atom, the O position is an oxygen atom; the B position is one or both of manganese or cobalt atoms; when the B position contains manganese and cobalt atoms at the same time, the content of one of them is less than 15%; when the B position contains manganese and cobalt atoms at the same time, the one with a smaller content at the B position is allowed to be further replaced by one or more atoms of magnesium, copper or iron, and the total amount of replacement of other atoms except the main element at the B position is less than 15%. It can be seen that the production method of zinc oxide-based varistor ceramics sintered at a low temperature within a certain range has the problem that the material density of the particles after particle forming becomes low due to excessive penetration of moisture in the air during the granulation molding process, and the movement rate of the particle powder decreases during the green sheet pressing process, thereby reducing the production quality of the ceramic green sheet. Summary of the invention

[0004] To this end, the present invention provides a method for producing burr-free varistor ceramic green sheets, so as to overcome the problems in the prior art that the material density of the particles becomes low after the particles are formed due to excessive penetration of moisture in the air during the granulation process, and the movement rate of the particle powder decreases due to the particle size distribution during the green sheet pressing process, thereby reducing the production quality of the ceramic green sheets.

[0005] To achieve the above object, the present invention provides a method for producing a burr-free varistor ceramic green sheet, comprising:

[0006] The raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form a mixed raw material powder;

[0007] The mixed raw material powder is introduced into a granulation molding machine to output test mixed particles;

[0008] Collecting the vertical movement rate of the test mixed particles;

[0009] Determining the granulation adjustment mode according to the vertical moving speed of the tested mixed particles, including adjusting the feeding speed of the mixed raw material powder of the granulation molding machine,

[0010] Or, the interval between the granulation forming time and the start pressing time of the mixed granules is determined according to the packing density of the tested mixed granules in a standard container;

[0011] Performing actual shaping of the mixed raw material powder according to the granulation adjustment method to output actual mixed particles;

[0012] Controlling a pressing device to press the actual mixed particles according to the granulation adjustment method to form a target green sheet of a corresponding shape;

[0013] Determining the cleaning rate of the flash according to the flash error of the target blank;

[0014] The flash is cleaned according to the cleaning rate to output a burr-free finished pressure-sensitive ceramic green sheet.

[0015] Furthermore, the raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form mixed raw material powder, including:

[0016] Using an electronic balance to weigh the raw materials of the varistor ceramic green sheet according to a preset formula;

[0017] Pour the weighed raw materials into a fluidized bed mixing device for mixing to form a mixed raw material;

[0018] The mixed raw material is ball milled and screened in sequence to output the mixed raw material powder.

[0019] Further, the adjusting the feeding speed of the mixed raw material powder of the granulation molding machine includes:

[0020] Detecting the vertical movement speed of the test mixed particles by a laser Doppler velocimeter;

[0021] Comparing the vertical movement rate of the test mixed particles with a preset first movement rate;

[0022] If the vertical moving speed of the mixed particles is less than the preset first moving speed, increasing the feeding speed of the mixed raw material powder;

[0023] The feed rate is the minimum speed of the test mixed particles in the feed hopper of the granulation machine.

[0024] Furthermore, the feeding speed of the mixed raw material powder is negatively correlated with the vertical moving speed of the mixed particles.

[0025] Furthermore, the step of determining the interval between the granulation forming time and the start pressing time of the mixed particles according to the packing density of the tested mixed particles in the standard container comprises:

[0026] Continuously comparing the vertical moving rate of the test mixed particles with a preset second moving rate;

[0027] If the vertical moving speed of the test mixed particles is greater than or equal to the preset first moving speed and less than the preset second moving speed, then obtaining the packing density of the test mixed particles in the standard container;

[0028] comparing the bulk density with a preset bulk density;

[0029] If the packing density is greater than the preset packing density, it is determined that the particle size distribution of the test mixed particles does not meet the requirements, and the interval between the granulation molding time and the start pressing time of the mixed particles is increased.

[0030] Furthermore, the interval duration is positively correlated with the stacking density.

[0031] Further, controlling a pressing device to press the actual mixed particles according to the granulation adjustment mode to form a target green sheet of a corresponding shape comprises:

[0032] injecting the mixed particles into a pressing die of a pressing device;

[0033] After standing for the interval time / standard interval time, the mixed particles are pressed to output a target green sheet.

[0034] Further, determining the cleaning rate of the flash according to the flash error of the target blank includes:

[0035] Using a three-dimensional profilometer to obtain the thickness of the flash edges of a plurality of target blanks;

[0036] Calculating an average thickness of the flash according to the thickness of the flash of a plurality of target blanks;

[0037] Calculating the error amount of the flash edge according to the difference between the average thickness of the flash edge and the edge thickness of the standard finished blank;

[0038] If the burr error is less than a preset error, the burr cleaning rate is reduced.

[0039] Furthermore, the error amount of the flash of the target blank is the absolute value of the difference between the average thickness of the flash of the target blank and the edge thickness of the standard finished blank.

[0040] Furthermore, the average thickness of the burrs is the ratio of the sum of the thicknesses of a plurality of burrs on a single target blank to the total number of burrs on the single target blank.

[0041] Compared with the prior art, the beneficial effects of the present invention are that the production method of the present invention can determine whether there are errors or problems in the granulation molding process by setting up a test process for the vertical movement rate of the mixed particles, and by adjusting the feeding speed of the mixed raw material powder of the granulation molding machine, the moisture in the air is more easily introduced into the raw materials due to insufficient feeding speed in the molding feeding process, thereby causing the particle density of the raw materials after granulation molding to become smaller, thereby causing the influence of inaccurate granulation size; by determining the interval between the granulation molding time and the start pressing time of the mixed particles according to the stacking density of the tested mixed particles in the standard container, the mixed particles formed in the granulation molding process can be accurately measured. Static electricity may occur between the mixed particles, which may lead to agglomeration and aggregation between the mixed particles. Therefore, the stacking density of the mixed particles in the standard container is detected to reflect the degree of static electricity between the mixed particles. Increasing the interval time can reduce the influence of static electricity between the mixed particles on the pressing uniformity during the pressing process. The principle is to increase the interval time to reduce the probability of static electricity. By determining the flash cleaning rate according to the flash error of the target blank, the influence of structural damage to the target blank during the cleaning process caused by excessive structural consistency between the target blank and the flash is reduced, thereby improving the production quality of burr-free varistor ceramic blanks.

[0042] Furthermore, the present invention overcomes the problem of low density of mixed particle material after molding due to excessive penetration of moisture in the air during the molding of mixed particles by the granulation molding machine by setting a preset first movement rate interval and increasing the feed rate of the mixed raw material according to the preset first movement rate interval. The feed rate is increased to reduce the chance of air entering the raw material, thereby improving the quality of the mixed particles.

[0043] Furthermore, the present invention overcomes the problem of increased aggregation of the mixed powders due to increased static electricity between the mixed powders, resulting in a decrease in the movement rate of the mixed powders and a decrease in the pressing uniformity during the pressing process, by setting a preset second moving rate and a preset stacking density and increasing the interval time of the pressing process of the mixed particles according to the preset stacking density, thereby improving the pressing effect of the green sheet.

[0044] Furthermore, the method of the present invention sets a preset error amount. When the error amount of the flash of the target blank is too small, it indicates that the consistency between the flash and the blank is better. When the consistency between the flash and the blank is higher, the flash cleaning rate is too high, which will cause the blank to be more prone to associated structural damage. This is because the structural consistency and correlation between the blank and the flash are too great, so the damage to one structure may lead to the damage of another structure. Therefore, the flash cleaning rate is reduced to overcome the problem of damage to the blank during the flash cleaning process. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is an overall flow chart of the method for producing a burr-free varistor ceramic green sheet according to an embodiment of the present invention;

[0046] Figure 2 A flow chart of adjusting the feed rate of the mixed raw material powder of the granulation molding machine in the method for producing the burr-free varistor ceramic green sheet according to an embodiment of the present invention;

[0047] Figure 3 The present invention is a flow chart of a method for producing a burr-free varistor ceramic green sheet according to an embodiment of the present invention, in which the burr cleaning rate is determined according to the burr error amount of the target green sheet. DETAILED DESCRIPTION

[0048] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0050] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a", "an" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in this specification refers to the presence of features, integers, steps, operations, elements / components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements / components. It should be understood that when we refer to a module as being "connected" or "coupled" to another module, it may be directly connected or coupled to the other module, or there may be an intermediate unit. In addition, "connected" or "coupled" used herein may include wireless connection or wireless coupling.

[0051] See also Figure 1 , Figure 2 as well as Figure 3 As shown, they are respectively an overall flow chart of the method for producing a burr-free varistor ceramic green sheet according to an embodiment of the present invention, a flow chart for adjusting the feed rate of the mixed raw material powder of the granulation molding machine, and a flow chart for determining the cleaning rate of the burr according to the burr error of the target green sheet. The method for producing a burr-free varistor ceramic green sheet according to an embodiment of the present invention comprises:

[0052] The raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form a mixed raw material powder;

[0053] The mixed raw material powder is introduced into a granulation molding machine to output test mixed particles;

[0054] collecting the vertical movement rate of the test mixed particles;

[0055] Determining the granulation adjustment mode according to the vertical moving speed of the tested mixed particles, including adjusting the feeding speed of the mixed raw material powder of the granulation molding machine,

[0056] Or, the interval between the granulation forming time and the start pressing time of the mixed granules is determined according to the packing density of the tested mixed granules in a standard container;

[0057] Performing actual shaping of the mixed raw material powder according to the granulation adjustment method to output actual mixed particles;

[0058] Controlling a pressing device to press the actual mixed particles according to the granulation adjustment method to form a target green sheet of a corresponding shape;

[0059] Determining the cleaning rate of the flash according to the flash error of the target blank;

[0060] The flash is cleaned according to the cleaning rate to output a burr-free finished pressure-sensitive ceramic green sheet.

[0061] Specifically, the horizontal plane is the plane where the output end of the granulation molding machine is located, and this plane is the plane of the platform, and the particles formed by the granulation molding machine roll to the target position on the platform.

[0062] The production method of the present invention can determine whether there are errors or problems in the granulation molding process by setting up a test process for the vertical movement rate of the mixed particles, and by adjusting the feeding speed of the mixed raw material powder of the granulation molding machine, the moisture in the air is more easily introduced into the raw materials due to insufficient feeding speed during the molding feeding process, thereby causing the particle density of the raw materials after granulation molding to become smaller, thereby causing the inaccurate granulation size to be affected; by determining the interval between the granulation molding time and the start pressing time of the mixed particles according to the stacking density of the tested mixed particles in the standard container, static electricity may occur between the mixed particles formed during the granulation molding process. Phenomenon, which leads to the phenomenon of agglomeration and aggregation between the mixed particles. Therefore, the stacking density of the mixed particles in the standard container is detected to reflect the degree of static electricity between the mixed particles. Increasing the interval time can reduce the influence of the static electricity between the mixed particles on the pressing uniformity during the pressing process. The principle is to increase the interval time to reduce the probability of static electricity. By determining the flash cleaning rate according to the flash error of the target blank, the influence of structural damage to the target blank during the cleaning process caused by the excessive structural consistency between the target blank and the flash is reduced, thereby achieving an improvement in the production quality of burr-free varistor ceramic blanks.

[0063] In practice, the present invention overcomes the local performance differences caused by uneven mixing of raw materials by sequentially mixing and ball-milling the raw materials of varistor ceramic green sheets to form a mixed raw material; determines the molding method of the raw materials and the particle pressing method according to the movement rate of the mixed raw materials during the introduction into the granulation molding machine, overcomes the problem of uneven molding particles caused by too fast or too slow feeding, and improves the uniformity and stability of the pressing effect; determines the flash cleaning rate according to the flash error amount of the target green sheet, overcomes the problem of green sheets, sintering adhesion or electrode preparation quality affected by flash, and improves the green sheet molding quality.

[0064] Specifically, the raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form a mixed raw material powder, including:

[0065] Using an electronic balance to weigh the raw materials of the varistor ceramic green sheet according to a preset formula;

[0066] Pour the weighed raw materials into a fluidized bed mixing device for mixing to form a mixed raw material;

[0067] The mixed raw material is ball milled and screened in sequence to output the mixed raw material powder.

[0068] Specifically, the mass ratio of the raw materials of the varistor ceramic green sheet is zinc oxide: bismuth: cobalt: manganese = 90:5:3:2, and a 200-mesh sieve is used to screen the mixed raw materials to output the mixed raw material powder.

[0069] Specifically, the adjusting the feeding speed of the mixed raw material powder of the granulation molding machine includes:

[0070] Detecting the vertical movement speed of the test mixed particles by a laser Doppler velocimeter;

[0071] Comparing the vertical movement rate of the test mixed particles with a preset first movement rate;

[0072] If the vertical moving speed of the mixed particles is less than the preset first moving speed, increasing the feeding speed of the mixed raw material powder;

[0073] The feeding speed is the minimum speed of the test mixed particles in the feeding device of the granulation molding machine.

[0074] In practice, it is understood by those skilled in the art that when the actual speed of the mixed raw material powder in the feeding device of the granulating machine is lower than the minimum speed, the moisture in the air penetrates too much into the mixed raw material powder.

[0075] Specifically, the feed rate of the mixed raw material powder is negatively correlated with the vertical moving speed of the mixed particles.

[0076] Specifically, the laser Doppler velocimeter is arranged at the outlet of the granulation molding machine.

[0077] Optionally, the preset first moving speed may be in a range of [0.2 m / s, 0.5 m / s], and the preset second moving speed may be in a range of [0.6 m / s, 1 m / s];

[0078] Preferably, the preferred embodiment of the preset first moving speed is 0.3 m / s, and the preferred embodiment of the preset second moving speed is 0.8 m / s.

[0079] In implementation, for every 0.05 m / s that the vertical movement rate of the test mixed particles is less than the preset first movement rate, 0.01 kg / min is added to the current feeding rate of the mixed raw material powder. For example, if the current feeding rate of the mixed raw material powder is 2.5 kg / min and the vertical movement rate of the test mixed particles is 0.2 m / s, the increased feeding rate of the mixed raw material powder is 2.5 kg / min + 0.01 kg / min × (0.3 m / s - 0.2 m / s) / 0.05 m / s = 2.52 kg / min.

[0080] In implementation, the present invention overcomes the problem of low density of mixed particle material after molding due to excessive penetration of moisture in the air during molding of mixed particles by the granulation molding machine by setting a preset first movement rate interval and increasing the feed rate of the mixed raw material according to the preset first movement rate interval. The feed rate is increased to reduce the chance of air entering the raw material, thereby improving the quality of the mixed particles.

[0081] Specifically, the method of determining the interval between the granulation forming time and the start pressing time of the mixed particles according to the packing density of the tested mixed particles in the standard container includes:

[0082] Continuously comparing the vertical moving rate of the test mixed particles with a preset second moving rate;

[0083] If the vertical moving speed of the test mixed particles is greater than or equal to the preset first moving speed and less than the preset second moving speed, then obtaining the packing density of the test mixed particles in the standard container;

[0084] comparing the bulk density with a preset bulk density;

[0085] If the packing density is greater than the preset packing density, it is determined that the particle size distribution of the test mixed particles does not meet the requirements, and the interval between the granulation molding time and the start pressing time of the mixed particles is increased.

[0086] Specifically, the interval duration is positively correlated with the stacking density.

[0087] Specifically, the bulk density of the test mixed particles in the standard container is the ratio of the total weight of the test mixed particles to the volume occupied by the test mixed particles in the standard container.

[0088] Specifically, the occupied volume of the test mixed particles in the standard container is measured by a distance sensor. Those skilled in the art will understand that the occupied volume of the test mixed particles in the standard container is calculated by collecting the distance sensor between the distance sensor and the surface of the test mixed particles in the standard container and the total volume of the standard container.

[0089] Specifically, the shape of the standard container can be a cuboid or a cylinder, preferably a cylinder.

[0090] Optionally, the preset bulk density may be in the range of [1.31 g / cm 3 , 1.39g / cm 3 ].

[0091] Preferably, the preferred embodiment of the preset bulk density is 1.35 g / cm³.

[0092] In implementation, for every 0.01 g / cm³ that the packing density of the tested mixed particles in the standard container is greater than the preset packing density, the interval duration of the pressing process of the mixed particles is increased by 1 s compared with the interval duration of the pressing process of the current mixed particles. For example, in one possible embodiment, the packing density of the tested mixed particles in the standard container is 1.38 g / cm³, the interval duration of the pressing process of the current mixed particles is 30 s, and the interval duration of the pressing process of the increased mixed particles is 30 s + (1.38 g / cm³ - 1.35 g / cm³) / 0.01 g / cm³ × 1s = 33 s.

[0093] In implementation, the present invention overcomes the problem of increased aggregation of the mixed powders due to increased static electricity between the mixed powders, resulting in a decrease in the movement rate of the mixed powders and a decrease in the pressing uniformity during the pressing process, by setting a preset second moving rate and a preset stacking density, and increasing the interval time of the pressing process of the mixed particles according to the preset stacking density, thereby improving the pressing effect of the green sheet.

[0094] Specifically, the pressing equipment is a tablet press.

[0095] Specifically, controlling the pressing device to press the actual mixed particles according to the granulation adjustment method to form a target green sheet of a corresponding shape includes:

[0096] injecting the mixed particles into a pressing die of a pressing device;

[0097] After standing for the interval time / standard interval time, the mixed particles are pressed to output a target green sheet.

[0098] Specifically, determining the cleaning rate of the flash according to the flash error of the target blank includes:

[0099] Using a three-dimensional profilometer to obtain the thickness of the flash edges of a plurality of target blanks;

[0100] Calculating an average thickness of the flash according to the thickness of the flash of a plurality of target blanks;

[0101] Calculating the error amount of the flash edge according to the difference between the average thickness of the flash edge and the edge thickness of the standard finished blank;

[0102] If the burr error is less than a preset error, the burr cleaning rate is reduced.

[0103] Specifically, the error amount of the burr of the target blank is the absolute value of the difference between the average thickness of the burr of the target blank and the edge thickness of the standard finished blank.

[0104] Specifically, the average thickness of the flash is the ratio of the sum of the thicknesses of several flashes on a single target blank to the total number of flashes on the single target blank.

[0105] Optionally, the preset error value range is [0.6mm, 0.8mm].

[0106] Preferably, a preferred embodiment of the preset error amount is 0.7 mm.

[0107] In practice, for every 0.1 mm below the preset error, the cleaning rate of the burrs is reduced by 1 cm compared to the current cleaning rate of the burrs. 2 / min, for example, the flash error is 0.6mm, and the current flash cleaning rate is 20cm 2 / min, the cleaning rate of the reduced flash is 20-(0.7-0.6) / 0.1×1=19cm 2 / min.

[0108] In implementation, the method of the present invention sets a preset error amount. When the error amount of the flash of the target blank is too small, it indicates that the consistency between the flash and the blank is better. When the consistency between the flash and the blank is higher, the flash cleaning rate is too high, which will cause the blank to be more prone to associated structural damage. This is because the structural consistency and correlation between the blank and the flash are too great, so the damage to one structure may lead to the damage of another structure. Therefore, the flash cleaning rate is reduced to overcome the problem of damage to the blank during the flash cleaning process.

[0109] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for producing a burr-free varistor ceramic green sheet, characterized in that: include: The raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form a mixed raw material powder; The mixed raw material powder is introduced into a granulation molding machine to output test mixed particles; collecting the vertical movement rate of the test mixed particles; Determining the granulation adjustment mode according to the vertical moving speed of the tested mixed particles, including adjusting the feeding speed of the mixed raw material powder of the granulation molding machine, Or, the interval between the granulation forming time and the start pressing time of the mixed granules is determined according to the packing density of the tested mixed granules in a standard container; Performing actual shaping of the mixed raw material powder according to the granulation adjustment method to output actual mixed particles; Controlling a pressing device to press the actual mixed particles according to the granulation adjustment method to form a target green sheet of a corresponding shape; Determining the cleaning rate of the flash according to the flash error of the target blank; Cleaning the flash edge at the cleaning rate to output a burr-free finished piezoceramic green sheet; The step of adjusting the feeding speed of the mixed raw material powder of the granulation molding machine comprises: Detecting the vertical movement speed of the test mixed particles by a laser Doppler velocimeter; Comparing the vertical movement rate of the test mixed particles with a preset first movement rate; If the vertical moving speed of the mixed particles is less than the preset first moving speed, increasing the feeding speed of the mixed raw material powder; Wherein, the feeding speed is the minimum speed of the test mixed particles in the feeding hopper of the granulation molding machine; The feed rate of the mixed raw material powder is negatively correlated with the vertical movement rate of the mixed particles; The method of determining the interval between the granulation forming time and the start pressing time of the mixed particles according to the packing density of the tested mixed particles in the standard container comprises: Continuously comparing the vertical moving rate of the test mixed particles with a preset second moving rate; If the vertical moving speed of the test mixed particles is greater than or equal to the preset first moving speed and less than the preset second moving speed, then obtaining the packing density of the test mixed particles in the standard container; comparing the bulk density with a preset bulk density; If the bulk density is greater than the preset bulk density, it is determined that the particle size distribution of the test mixed particles does not meet the requirements, and the interval between the granulation molding time and the start pressing time of the mixed particles is increased; The interval duration is positively correlated with the packing density.

2. The method for producing a burr-free varistor ceramic green sheet according to claim 1, characterized in that: The raw materials of the varistor ceramic green sheet are sequentially mixed and ball-milled to form mixed raw material powder, comprising: Using an electronic balance to weigh the raw materials of the varistor ceramic green sheet according to a preset formula; Pour the weighed raw materials into a fluidized bed mixing device for mixing to form a mixed raw material; The mixed raw materials are successively ball milled and screened to output the mixed raw material powder.

3. The method for producing a burr-free varistor ceramic green sheet according to claim 2, characterized in that: Controlling a pressing device to press the actual mixed particles according to the granulation adjustment mode to form a target green sheet of a corresponding shape, comprising: injecting the mixed particles into a pressing die of a pressing device; After standing for the interval time / standard interval time, the mixed particles are pressed to output a target green sheet.

4. The method for producing a burr-free varistor ceramic green sheet according to claim 3, characterized in that: Determining the cleaning rate of the flash according to the flash error of the target blank includes: Using a three-dimensional profilometer to obtain the thickness of the flash edges of a plurality of target blanks; Calculating an average thickness of the flash according to the thickness of the flash of a plurality of target blanks; Calculating the error amount of the flash edge according to the difference between the average thickness of the flash edge and the edge thickness of the standard finished blank; If the burr error is less than a preset error, the burr cleaning rate is reduced.

5. The method for producing a burr-free varistor ceramic green sheet according to claim 4, characterized in that: The error amount of the flash edge of the target blank is the absolute value of the difference between the average thickness of the flash edge of the target blank and the edge thickness of the standard finished blank.

6. The method for producing a burr-free varistor ceramic green sheet according to claim 5, characterized in that: The average thickness of the flash is the ratio of the sum of the thicknesses of several flashes on a single target blank to the total number of flashes on the single target blank.

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