A ball milling device for flaky copper powder for silver-coated copper and a method of use

Abstract

This invention relates to the field of ball milling equipment technology, specifically a ball milling device and method for processing flake copper powder for silver-plated copper. The device includes a ball milling cylinder, with ball milling components arranged both inside and outside the cylinder. A gradient guide cylinder is fixedly installed on the outer side of a mounting frame. The gradient guide cylinder has a structure that is wider at the top and narrower at the bottom, with a reduced diameter in the middle. An anti-sticking liner assembly is provided on the inner wall of the ball milling cylinder, and a floating scraper assembly is installed on the shaft wall of the drive shaft. The anti-sticking liner assembly of this invention, through its circumferential corrugated pattern, vertical guide grooves, and concave-convex dot matrix design, disrupts the stagnant layer on the cylinder wall, reducing powder adhesion. The floating scraper assembly, supported by springs, ensures that the scraper blade is in constant contact with the liner for scraping, and, in conjunction with a ball bearing, enhances the cleaning effect. This fundamentally prevents powder from sticking to the wall, clumping, and accumulating, ensuring uniform dispersion of copper powder particles. This allows for continuous and dense silver coating during subsequent silver plating, avoiding problems such as incomplete coating or uneven silver layer thickness.

Description

Technical Field

[0001] This invention relates to the field of ball milling equipment technology, specifically to a ball milling device and method for producing flake copper powder for silver-coated copper. Background Technology

[0002] Silver-coated copper powder, with its superior conductivity, lower cost than pure silver powder, and excellent oxidation resistance and electromagnetic shielding performance, is widely used in conductive pastes, electromagnetic shielding materials, electronic packaging, photovoltaic electrodes, and high-end electronic components. In the silver-coated copper powder preparation process, flake copper powder serves as the core substrate. Its flake shape regularity, aspect ratio, surface smoothness, and powder dispersion uniformity directly determine the uniformity, adhesion, conductivity stability, and oxidation and corrosion resistance of the subsequent electroless silver plating layer. Compared to spherical copper powder, flake copper powder has a larger specific surface area and better surface activity compatibility, making it easier to achieve continuous and dense silver plating. It is a key precursor material for preparing high-quality silver-coated copper powder.

[0003] Currently, the industry commonly uses ball milling equipment to roll and modify spherical electrolytic copper powder and atomized copper powder into flake copper powder. Existing mass production equipment mainly includes horizontal drum ball mills and conventional vertical stirred ball mills. Among them, conventional vertical stirred ball mills have gradually become the mainstream equipment for processing flake copper powder due to their advantages of compact structure, high grinding efficiency, and ease of pilot testing and mass production scaling.

[0004] However, in the actual ball milling production of silver-coated copper flakes, the existing traditional vertical stirred ball mills have a smooth straight cylindrical structure inside the cylinder. The slurry is prone to forming a static retention boundary layer on the wall surface, and the copper powder particles are very easy to stick to the wall. Long-term retention and accumulation will lead to powder agglomeration and clumping, and the flake morphology will be destroyed. Summary of the Invention

[0005] The purpose of this invention is to provide a ball milling device and a method for using flake copper powder for silver-coated copper, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a ball milling device for producing flake copper powder for silver-coated copper, comprising a ball milling cylinder, wherein a ball milling assembly is provided both inside and outside the ball milling cylinder, the ball milling assembly comprising a drive motor and a reducer fixedly installed at the middle position of the upper end of the ball milling cylinder, the output end of the drive motor being connected to a transmission shaft through the reducer and a coupling, wherein a first stirring and dispersing disc and a second stirring and dispersing disc are fixedly installed on the upper and lower outer walls of the transmission shaft, respectively, and inclined blades are fixedly installed on the upper and lower end faces of both the first stirring and dispersing disc and the second stirring and dispersing disc; A fixed frame is fixedly installed at the middle position of the drive shaft, and a gradient guide tube is fixedly installed on the outside of the fixed frame. The gradient guide tube has a structure that is wider at the top and narrower at the bottom, with a reduced diameter in the middle.

[0007] Preferably, a sealing rotating sleeve is fixedly installed at the connection between the drive shaft and the ball mill cylinder, and multiple staggered hollow openings are provided inside the first and second stirring and dispersing discs, with the staggered hollow openings on the first and second stirring and dispersing discs being staggered.

[0008] Preferably, an inverted conical stirring head is fixedly installed at the bottom end of the drive shaft, a plurality of vortex vanes are fixedly installed on the conical surface of the stirring head, and a paddle is fixedly installed on the bottom end surface of the stirring head.

[0009] Preferably, the ball mill cylinder is provided with a temperature control component inside. The temperature control component includes an assembly groove formed on the bottom end face of the ball mill cylinder. A temperature control box is fixedly installed inside the assembly groove, and a cooling plate is embedded in the inner wall of the temperature control box.

[0010] Preferably, a power supply is installed inside the assembly slot, a circulating pump is fixedly connected to the output end of the temperature control box, the output end of the circulating pump is connected to a refrigerant pipeline, and multiple connecting holes are opened on the bottom end face side wall of the ball mill cylinder.

[0011] Preferably, the inner wall of the ball mill cylinder is provided with an anti-sticking liner assembly. The anti-sticking liner assembly includes a liner fixedly installed on the inner wall of the ball mill cylinder. The inner wall of the liner is fixedly installed with a plurality of equidistant circumferential corrugations. The inner wall of the liner is also provided with a plurality of vertical guide grooves distributed at equal angles. The inner wall of the liner is also provided with a plurality of concave and convex dot arrays.

[0012] Preferably, a floating scraper assembly is installed on the shaft wall of the drive shaft. The floating scraper assembly includes a hollow support cylinder fixedly installed on the shaft wall of the drive shaft. A spring is installed inside the hollow support cylinder, and a support slide column is slidably installed at the front end of the hollow support cylinder.

[0013] Preferably, a scraper is fixedly installed at the other end of the supporting slide column, and multiple bouncing balls are installed on the scraper.

[0014] Preferably, the ball mill cylinder has multiple grinding balls distributed inside, the upper end of the ball mill cylinder is fixedly connected to a feed valve pipe, and the bottom side wall of the ball mill cylinder is fixedly connected to a discharge valve pipe.

[0015] Preferably, a method of using a ball milling device for producing flake copper powder for silver-coated copper includes the following steps: S1. Feeding preparation: Open the feed valve pipe at the top of the ball mill cylinder, and put spherical copper powder, wet grinding media and grinding balls into the ball mill cylinder according to the preset ratio. After feeding is completed, close the feed valve pipe to ensure that the cylinder is sealed.

[0016] S2. Equipment Start-up: The drive assembly and temperature control assembly are started simultaneously. The drive motor drives the transmission shaft and various stirring and scraping components to rotate via the reducer. The temperature control assembly starts the refrigeration and refrigerant circulation to regulate the temperature inside the cylinder to 30-40℃.

[0017] S3. Grinding operation: During equipment operation, the stirring and dispersing disc, the gradient guide cylinder, and the bottom stirring head work together to achieve forced circulation and uniform grinding of the slurry. The floating scraping component cleans the cylinder wall simultaneously to prevent powder from adhering to the wall and agglomerating. Grinding continues until the flaky copper powder reaches the preset diameter-to-thickness ratio requirement.

[0018] S4. Stop and discharge: After the preset grinding time is reached, turn off the drive motor and temperature control components. After the equipment stops and the pressure inside the cylinder returns to normal, open the discharge valve at the bottom of the cylinder to discharge the ground flaky copper powder slurry, thus completing one operation.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The anti-sticking liner component of this invention uses a design of circumferential wave pattern, vertical flow guide groove and concave-convex dot matrix to break the stagnant layer on the cylinder wall and reduce powder adhesion to the wall; the floating scraper component, with the elastic support of springs, allows the scraper to keep close to the liner in real time for scraping, and the ball enhances the cleaning effect, thus preventing powder from sticking to the wall, clumping, and accumulating at the source, ensuring that the copper powder particles are evenly dispersed, and achieving continuous and dense silver coating during subsequent silver plating, avoiding problems such as missed coating and uneven silver layer thickness.

[0020] The first and second stirring and dispersing discs of this invention feature inclined blades and staggered hollow openings, which enhance axial flow and circumferential shear force, break the laminar flow state of the slurry, and avoid local over-grinding or failure to form flakes. The gradient guide tube and the stirring assembly work together to form a forced double circulation flow with "inner lower and outer upper" to eliminate dead angles in the flow field, so that all copper powder can be subjected to uniform friction and rolling action, ensuring that the flake copper powder has a regular morphology and stable aspect ratio, and improving the conductivity and oxidation resistance of the silver-coated copper powder. The present invention features an inverted conical stirring head at the bottom of the drive shaft, which is equipped with a vortex and a paddle to forcibly disperse the grinding balls and copper powder accumulated at the bottom of the cylinder, preventing the powder from being compacted and forming hard agglomerates, further ensuring uniform powder dispersion and improving the flake rate.

[0021] The multi-layer stirring and dispersing disc of this invention features an inclined blade design and staggered hollow openings. Combined with the forced circulation formed by the gradient guide tube, this significantly increases the contact frequency between the grinding balls and copper powder, resulting in more thorough shearing and crushing effects. Compared to traditional equipment, this effectively shortens the grinding cycle and improves production efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the three-dimensional structure in this invention; Figure 2This is a schematic diagram of the internal structure of the ball mill cylinder in this invention; Figure 3 This is a schematic diagram of the ball mill assembly structure in this invention; Figure 4 This is a schematic diagram of the temperature control component structure in this invention; Figure 5 This is a schematic diagram of the stirring and dispersing disc structure in this invention; Figure 6 This is a schematic diagram of the gradient guide tube structure in this invention; Figure 7 This is a schematic diagram of the anti-stick liner assembly structure in this invention; Figure 8 This is a schematic diagram of the floating wall scraping component structure in this invention.

[0023] In the diagram: 1. Ball mill cylinder; 2. Feed valve pipe; 3. Discharge valve pipe; 4. Ball mill assembly; 401. Drive motor; 402. Reducer; 403. Sealing rotating sleeve; 404. Drive shaft; 405. First stirring and dispersing disc; 406. Second stirring and dispersing disc; 407. Staggered hollow opening; 408. Inclined blade; 409. Fixing frame; 410. Gradient guide tube; 411. Stirring head; 412. Vortex; 413. Paddle; 5. Temperature control. Components; 501, Assembly slot; 502, Temperature control box; 503, Circulation pump; 504, Refrigerant pipe; 505, Connecting hole; 506, Cooling chip; 507, Power supply; 6, Anti-stick liner assembly; 601, Liner; 602, Corrugated pattern; 603, Flow guide channel; 604, Concave-convex dot matrix; 7, Floating scraper assembly; 701, Hollow support cylinder; 702, Spring; 703, Support slide column; 704, Scraper strip; 705, Ball; 8, Grinding ball. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0025] Please see Figures 1 to 8As shown, a ball milling device for producing flake copper powder for silver-coated copper includes a ball milling cylinder 1. Multiple grinding balls 8 are distributed inside the ball milling cylinder 1. A feed valve pipe 2 is fixedly connected to the upper end of the ball milling cylinder 1, and a discharge valve pipe 3 is fixedly connected to the bottom side wall of the ball milling cylinder 1. A ball milling assembly 4 is arranged both inside and outside the ball milling cylinder 1. The ball milling assembly 4 includes a drive motor 401 and a reducer 402 fixedly installed at the middle position of the upper end of the ball milling cylinder 1. The output end of the drive motor 401 is connected to a transmission shaft 404 through the reducer 402 and a coupling. A first stirring and dispersing disc 405 and a second stirring and dispersing disc 406 are fixedly installed on the upper and lower outer walls of the transmission shaft 404, respectively. Inclined... Leaf 408; A fixed bracket 409 is fixedly installed at the middle position of the drive shaft 404, and a gradient guide tube 410 is fixedly installed on the outside of the fixed bracket 409. The gradient guide tube 410 has a structure that is wider at the top and narrower at the bottom, with a reduced diameter in the middle. A sealing rotating sleeve 403 is fixedly installed at the connection between the drive shaft 404 and the ball mill cylinder 1. Multiple staggered hollow openings 407 are opened inside the first stirring and dispersing disc 405 and the second stirring and dispersing disc 406. The staggered hollow openings 407 on the first stirring and dispersing disc 405 and the second stirring and dispersing disc 406 are staggered. An inverted conical stirring head 411 is fixedly installed at the bottom end of the drive shaft 404. Multiple vortex blades 412 are fixedly installed on the conical surface of the stirring head 411, and a paddle 413 is fixedly installed on the bottom end surface of the stirring head 411.

[0026] By adopting the above technical solution, spherical copper powder, wet grinding media (solvent + dispersant), and grinding balls 8 are fed into the ball mill cylinder 1 in a preset ratio through the feed valve pipe 2 at the upper end of the ball mill cylinder 1. The feed valve pipe 2 is then closed to ensure the cylinder is sealed. At the same time, the ball mill assembly 4 is started to complete the power preparation of the equipment. The sealing rotating sleeve 403 works simultaneously to seal the connection between the drive shaft 404 and the ball mill cylinder 1, preventing slurry leakage and the entry of outside air, and avoiding oxidation of the copper powder.

[0027] After the drive motor 401 starts, the output power is reduced in speed and increased in torque by the reducer 402, and then transmitted to the transmission shaft 404 through the coupling, which drives the transmission shaft 404 to rotate stably, thereby driving the first stirring and dispersing disc 405, the second stirring and dispersing disc 406, the fixed frame 409, the stirring head 411 and the floating scraper assembly 7 fixed on it to rotate synchronously.

[0028] When the first mixing and dispersing disc 405 and the second mixing and dispersing disc 406 rotate, the inclined blades 408 on their upper and lower end faces generate axial thrust and circumferential shear force. On the one hand, this drives the grinding balls 8 and the slurry to make high-speed circular motion. By utilizing the friction and crushing action between the grinding balls 8 and between the grinding balls 8 and the slurry, the spherical copper powder is gradually crushed into flakes. On the other hand, the axial thrust of the inclined blades 408, combined with the staggered hollow openings 407 inside the dispersing disc, breaks the laminar flow state of the slurry and prevents the powder from clumping together between the discs. The staggered hollow openings 407 can reduce the inertia of the slurry moving synchronously with the dispersing disc, while realizing the vertical connection of the slurry, enhancing the dispersion effect, and improving the consistency of the aspect ratio of the flake copper powder.

[0029] The fixed bracket 409 at the middle position of the drive shaft 404 drives the gradual guide tube 410 to be fixed synchronously. The gradual guide tube 410 divides the inside of the ball mill cylinder 1 into the inner part of the central flow channel and the outer ring flow channel (between the guide tube and the inner wall of the cylinder). The centrifugal inertial force generated by the rotation of the first stirring and dispersing disc 405 and the second stirring and dispersing disc 406 throws the slurry to the outer ring flow channel, causing the pressure in the outer ring flow channel to increase. At the same time, the axial thrust of the inclined blade 408 pushes the slurry in the central area inside the guide tube downward, making the pressure on the inside lower, forming a pressure difference driving force of "high pressure on the outside and low pressure on the inside". Under the combined action of centrifugal force, axial thrust, and pressure difference, the slurry flows downward along the inside of the gradually changing guide cylinder 410. After reaching the bottom of the cylinder, it is dispersed by the stirring head 411 and diffuses to the surroundings, entering the outer ring channel. Then, it rises back along the outer ring and flows back into the center of the guide cylinder, forming a stable double-circulation forced circulation of "inner lower and outer upper". This completely eliminates dead angles in the flow field inside the cylinder, ensuring that all copper powder can be ground evenly and avoiding local over-grinding or failure to form flakes.

[0030] The inverted conical stirring head 411 at the bottom of the drive shaft 404 rotates synchronously, and the vortex plate 412 on its conical surface generates a strong shearing force, which forcibly disperses and lifts the grinding balls 8 and the settled copper powder at the bottom of the cylinder, preventing the powder from being compacted and forming hard agglomerates; the paddle plate 413 on the bottom end face of the stirring head 411 further scrapes the bottom of the cylinder to prevent the powder from sticking to the bottom wall and accumulating material, ensuring that the material at the bottom fully participates in the grinding cycle.

[0031] Specifically, such as Figures 6 to 8As shown, an anti-sticking liner assembly 6 is provided on the inner wall of the ball mill cylinder 1. The anti-sticking liner assembly 6 includes a liner 601 fixedly installed on the inner wall of the ball mill cylinder 1. Multiple circumferentially distributed wavy lines 602 are fixedly installed on the inner wall of the liner 601. Multiple vertically distributed guide grooves 603 are also distributed on the inner wall of the liner 601 at equal angles. Multiple concave-convex dot matrix 604 is also provided on the inner wall of the liner 601. A floating scraper assembly 7 is installed on the shaft wall of the drive shaft 404. The floating scraper assembly 7 includes a hollow support cylinder 701 fixedly installed on the shaft wall of the drive shaft 404. A spring 702 is installed inside the hollow support cylinder 701. A support slide column 703 is slidably installed at the front end of the hollow support cylinder 701. A scraper 704 is fixedly installed at the other end of the support slide column 703. Multiple bouncing balls 705 are installed on the scraper 704.

[0032] By adopting the above technical solution, the anti-sticking liner component 6 on the inner wall of the ball mill cylinder 1 plays a core anti-sticking role. The circumferential wave pattern 602, vertical guide groove 603, and concave-convex dot matrix 604 on the inner wall of the liner 601 break the static retention boundary layer of the slurry on the cylinder wall and reduce powder adhesion to the wall. At the same time, the floating scraper component 7 rotates synchronously with the drive shaft 404. The spring 702 inside the hollow support cylinder 701 provides elastic support, pushing the support slide column 703 to drive the scraper 704 to stick tightly to the inner wall of the liner 601 and scrape the slurry and powder adhering to the wall surface in real time. The ball 705 on the scraper 704 can enhance the scraping effect and at the same time avoid the scraper 704 from scratching the liner 601, realizing the self-cleaning of the cylinder wall and solving the problem of powder sticking and agglomeration from the root.

[0033] Specifically, such as Figures 1 to 6 As shown, a temperature control component 5 is provided inside the ball mill cylinder 1. The temperature control component 5 includes an assembly groove 501 opened on the bottom end face of the ball mill cylinder 1. A temperature control box 502 is fixedly installed inside the assembly groove 501. A cooling plate 506 is embedded in the inner wall of the temperature control box 502. A power supply 507 is also installed inside the assembly groove 501. The output end of the temperature control box 502 is fixedly connected to a circulation pump 503. The output end of the circulation pump 503 is connected to a refrigerant pipe 504. Multiple connecting holes 505 are opened on the side wall of the bottom end face of the ball mill cylinder 1.

[0034] By adopting the above technical solution, during the grinding process, the frictional heat generated by stirring and grinding will cause the temperature inside the cylinder to rise, which can easily lead to copper powder oxidation, dispersant failure, and powder agglomeration. At this time, the temperature control component 5 is activated, the power supply 507 supplies power to the cooling chip 506, the cooling chip 506 cools the refrigerant in the temperature control box 502, and the circulation pump 503 works to extract the refrigerant inside the temperature control box 502 and transport it to the refrigerant pipeline 504 for circulation. The refrigerant pipeline 504 is S-shaped and embedded in the inner wall of the ball mill cylinder 1, which allows the temperature inside the refrigerant pipeline 504 to be transferred to the ball mill cylinder 1, thereby controlling the temperature of the raw material in the refrigerant pipeline 504. The annular and S-shaped distribution design of the refrigerant pipeline 504 can improve the uniform cooling effect of the device. The end of the refrigerant pipeline 504 is connected to the temperature control box 502. The refrigerant circulates between the cylinder wall and the temperature control box 502, quickly removing the heat generated during grinding and controlling the temperature inside the cylinder within a reasonable range (30-40℃) suitable for the formation of copper powder flakes. This ensures the stability of the quality of the flake copper powder and prevents oxidation. After the copper powder has been ground for a preset time and meets the aspect ratio and morphology requirements for silver-coated copper flakes, the drive motor 401 and the temperature control component 5 are turned off. Once the equipment has completely stopped and the pressure inside the cylinder has returned to normal, the discharge valve pipe 3 on the bottom side wall of the ball mill cylinder 1 is opened to discharge the ground flake copper powder slurry, completing one grinding operation. If continuous production is required, the above feeding, grinding, and discharging process can be repeated.

[0035] It should be noted that this equipment requires a dedicated control system and matching sensors to achieve precise control, status monitoring, and safety protection during the grinding process. The specific configuration and functions are as follows: 1. Control System: Utilizing a frequency converter control cabinet, it can preset and adjust the drive motor speed (30-50 rpm), grinding time (15-17 hours), and temperature range (30-40℃). It also features overload protection, emergency stop control, and operating status display functions. It can receive sensor feedback signals in real time and automatically adjust equipment operating parameters; 2. Core sensors: Equipped with a temperature sensor embedded in the inner wall of the ball mill cylinder 1, the temperature sensor monitors the temperature of the slurry inside the cylinder in real time and transmits the signal to the control system. When the temperature exceeds the range of 30-40℃, the control system automatically adjusts the cooling power of the temperature control component 5 to ensure temperature stability. Equipped with a pressure sensor installed at the upper end of the ball mill cylinder 1, the pressure sensor monitors the pressure inside the cylinder to prevent abnormal pressure from causing leakage. Equipped with a speed sensor installed on the drive shaft 404, the speed of the drive shaft 404 is fed back in real time to ensure stable grinding speed. Optional particle size sensor is available to monitor the aspect ratio of copper powder in the slurry in real time. When the preset requirement of 10-50 is reached, the sensor automatically reminds the machine to stop, accurately controlling the grinding endpoint.

[0036] A method for using a ball milling device for producing flake copper powder for silver-coated copper includes the following steps: S1. Feeding preparation: Open the feed valve pipe 2 at the upper end of the ball mill cylinder 1, and put the spherical copper powder, wet grinding media and grinding balls 8 into the ball mill cylinder 1 according to the preset ratio. After feeding is completed, close the feed valve pipe 2 to ensure that the cylinder is sealed.

[0037] S2. Equipment Start-up: The drive assembly and temperature control assembly are started synchronously. The drive motor 401 drives the transmission shaft 404 and various stirring and scraping components to rotate via the reducer 402. The temperature control assembly starts the refrigeration and refrigerant circulation to regulate the temperature inside the cylinder to 30-40℃.

[0038] S3. Grinding operation: During equipment operation, the stirring and dispersing disc, the gradient guide cylinder 410, and the bottom stirring head 411 work together to achieve forced circulation and uniform grinding of the slurry. The floating scraper component 7 cleans the cylinder wall simultaneously to prevent powder from adhering to the wall and agglomerating. Grinding continues until the flaky copper powder reaches the preset diameter-to-thickness ratio requirement.

[0039] S4. Stop and discharge: After the preset grinding time is reached, turn off the drive motor 401 and the temperature control component. After the equipment stops and the pressure inside the cylinder returns to normal, open the discharge valve pipe 3 at the bottom of the cylinder to discharge the ground flaky copper powder slurry, thus completing one operation.

[0040] Working principle: Before starting the equipment, spherical copper powder, wet grinding media (solvent + dispersant), and grinding balls 8 are fed into the ball mill cylinder 1 through the feed valve pipe 2 at the upper end of the ball mill cylinder 1 in a preset ratio (ball-to-material ratio 20:1, slurry solid content 10-20%, solvent is propylene glycol / diethylene glycol ethyl ether, dispersant is tartaric acid / oleic acid, grinding balls are φ0.5-2mm zirconia balls or stainless steel beads). The feed valve pipe 2 is then closed to ensure the cylinder is sealed. Simultaneously, the ball mill assembly 4 is started to complete the power preparation. The connection between the transmission shaft 404 and the ball mill cylinder 1 is sealed to prevent slurry leakage and the entry of outside air, thus avoiding oxidation of the copper powder. After the drive motor 401 starts, the output power is reduced in speed and increased in torque by the reducer 402 (speed is adjusted to 30-50 rpm), and then transmitted to the transmission shaft 404 through the coupling, driving the transmission shaft 404 to rotate stably. This, in turn, drives the first stirring and dispersing disc 405, the second stirring and dispersing disc 406, the fixing frame 409, the stirring head 411, and the floating scraper assembly 7 fixed on it to rotate synchronously. The speed sensor monitors the speed of the transmission shaft 404 in real time and feeds it back to the control system to ensure stable speed. When the first stirring and dispersing disc 405 and the second stirring and dispersing disc 406 rotate, the inclined blades 408 on their upper and lower end faces generate axial thrust and circumferential shear force. On the one hand, the grinding balls 8 and the slurry move in a high-speed circular motion, and the friction and crushing action between the grinding balls 8 and between the grinding balls 8 and the slurry gradually crushes the spherical copper powder into flakes. On the other hand, the axial thrust of the inclined blade 408, combined with the staggered hollow openings 407 inside the dispersion disc, breaks the laminar flow state of the slurry and prevents the powder from clumping together between the discs. The staggered hollow openings 407 can reduce the inertia of the slurry moving in a synchronous circular motion with the dispersion disc, and at the same time realize the vertical connection of the slurry, enhance the dispersion effect, and improve the consistency of the aspect ratio of the flake copper powder. If equipped with a particle size sensor, the aspect ratio of the flake copper powder can be monitored in real time and fed back to the control system synchronously.

[0041] The fixed bracket 409 at the middle position of the drive shaft 404 drives the gradual guide tube 410 to be fixed synchronously. The gradual guide tube 410 has a gradual structure that is wider at the top and narrower at the bottom (gradient angle 5-10°), which divides the inside of the ball mill cylinder 1 into a central flow channel (inside the guide tube) and an outer ring flow channel (between the guide tube and the inner wall of the cylinder). The centrifugal inertial force generated by the rotation of the first stirring and dispersing disc 405 and the second stirring and dispersing disc 406 throws the slurry to the outer ring flow channel, increasing the pressure in the outer ring flow channel; at the same time, the axial thrust of the inclined blade 408 pushes the slurry in the central area inside the guide tube downward, making the inner pressure lower, forming a pressure difference driving force of "high pressure on the outside and low pressure on the inside". Under the combined action of centrifugal force, axial thrust, and pressure difference, the slurry flows downward along the inside of the gradually changing guide cylinder 410. After reaching the bottom of the cylinder, it is dispersed by the stirring head 411 and diffuses to the surroundings, entering the outer ring channel. Then, it rises back along the outer ring and flows back into the center of the guide cylinder, forming a stable double-circulation forced circulation of "inner lower and outer upper". This completely eliminates dead angles in the flow field inside the cylinder, ensuring that all copper powder can be ground evenly and avoiding local over-grinding or failure to form flakes.

[0042] The inverted conical stirring head 411 at the bottom of the drive shaft 404 rotates synchronously, and the vortex 412 on its conical surface generates strong shearing force, which forcibly disperses and lifts the grinding balls 8 and the settled copper powder at the bottom of the cylinder, preventing the powder from being compacted and forming hard agglomerates. The paddle 413 at the bottom of the stirring head 411 further scrapes the bottom of the cylinder to prevent the powder from sticking to the bottom wall and accumulating material, ensuring that the material at the bottom fully participates in the grinding cycle. The paddle 413 can also better discharge the slurry from the discharge valve pipe 3 by moving the slurry.

[0043] The anti-sticking liner assembly 6 on the inner wall of the ball mill cylinder 1 plays a core anti-sticking role. The circumferential wave pattern 602, vertical guide groove 603, and concave-convex dot matrix 604 on the inner wall of the liner 601 break the static retention boundary layer of the slurry on the cylinder wall and reduce powder adhesion to the wall. At the same time, the floating scraper assembly 7 rotates synchronously with the drive shaft 404. The spring 702 (elastic coefficient 5-8N / mm) inside the hollow support cylinder 701 provides elastic support, pushing the support slide column 703 to drive the scraper 704 to stick tightly to the inner wall of the liner 601 and scrape the slurry and powder adhering to the wall surface in real time. The ball 705 on the scraper 704 can enhance the scraping effect and at the same time prevent the scraper 704 from scratching the liner 601, realizing the self-cleaning of the cylinder wall and solving the problem of powder sticking and agglomeration from the root.

[0044] During the grinding process, the frictional heat generated by stirring and grinding can cause the temperature inside the mill cylinder to rise, which can easily lead to copper powder oxidation, dispersant failure, and powder agglomeration. A temperature sensor monitors the temperature inside the mill cylinder in real time and transmits the signal to the control system. When the temperature exceeds the range of 30-40℃, the temperature control component 5 automatically starts, and the power supply 507 supplies power to the cooling element 506. The cooling element 506 cools the refrigerant (using ethylene glycol aqueous solution) in the temperature control chamber 502. The circulating pump 503 delivers the cooled refrigerant through the refrigerant pipe 504 to the inner wall of the ball mill cylinder 1. After circulating along the cylinder wall interlayer, the refrigerant returns to the temperature control chamber 502 for further cooling, forming a complete cycle. This quickly removes the heat generated during grinding, stabilizing the temperature inside the mill cylinder at 30-40℃, ensuring stable quality of the flake copper powder and preventing oxidation. A pressure sensor monitors the pressure inside the mill cylinder in real time. If an abnormal pressure occurs (above atmospheric pressure by 0.1 MPa or below atmospheric pressure), the control system immediately issues an alarm and shuts down the machine to prevent equipment damage or copper powder oxidation.

[0045] When the copper powder has been ground for a preset time (15-17 hours), or when the particle size sensor detects that the copper powder diameter-to-thickness ratio reaches 10-50 and the preset morphology requirements, the control system automatically prompts for shutdown. The operator shuts off the drive motor 401 and the temperature control component 5. After the equipment has completely stopped and the pressure inside the cylinder (confirmed by the pressure sensor) has returned to normal pressure, the discharge valve pipe 3 on the bottom side wall of the ball mill cylinder 1 is opened to discharge the ground flake copper powder slurry, completing one operation. If continuous production is required, the above feeding, grinding, and discharging process can be repeated. Throughout the entire operation, the various components, control system, and sensors work together to achieve efficient and uniform rolling of spherical copper powder into flake copper powder. Through mechanical structure optimization and precise control, the problems of powder agglomeration, wall adhesion, dead zones in the flow field, and temperature rise oxidation existing in traditional equipment are fundamentally solved, ensuring that the produced flake copper powder meets the requirements of the subsequent silver plating process for silver-coated copper, and ensuring the uniformity of the coating and conductivity of the silver-coated copper powder.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A ball milling apparatus for producing flake copper powder for silver-coated copper, comprising a ball milling cylinder, characterized in that, The ball mill cylinder is equipped with a ball mill assembly both inside and outside. The ball mill assembly includes a drive motor and a reducer fixedly installed at the middle position of the upper end of the ball mill cylinder. The output end of the drive motor is connected to a transmission shaft through the reducer and a coupling. A first stirring and dispersing disc and a second stirring and dispersing disc are fixedly installed on the upper and lower outer walls of the transmission shaft, respectively. Inclined blades are fixedly installed on the upper and lower end faces of both the first stirring and dispersing disc and the second stirring and dispersing disc. A fixed frame is fixedly installed at the middle position of the drive shaft, and a gradient guide tube is fixedly installed on the outside of the fixed frame. The gradient guide tube has a structure that is wider at the top and narrower at the bottom, with a reduced diameter in the middle. An anti-sticking liner assembly is provided on the inner wall of the ball mill cylinder, and a floating scraper assembly is installed on the shaft wall of the drive shaft.

2. The ball milling equipment for producing flake copper powder for silver-coated copper as described in claim 1, characterized in that: A sealing rotating sleeve is fixedly installed at the connection between the drive shaft and the ball mill cylinder. The interior of both the first and second stirring and dispersing discs is provided with multiple staggered hollow openings. The staggered hollow openings on the first and second stirring and dispersing discs are staggered.

3. The ball milling equipment for producing flake copper powder for silver-coated copper according to claim 2, characterized in that: An inverted conical stirring head is fixedly installed at the bottom end of the drive shaft. Multiple vortex vanes are fixedly installed on the conical surface of the stirring head, and a paddle is fixedly installed on the bottom end surface of the stirring head.

4. The ball milling equipment for producing flake copper powder for silver-coated copper as described in claim 3, characterized in that: The ball mill cylinder is equipped with a temperature control component. The temperature control component includes an assembly groove formed on the bottom end face of the ball mill cylinder. A temperature control box is fixedly installed inside the assembly groove, and a cooling plate is embedded in the inner wall of the temperature control box.

5. The ball milling equipment for producing flake copper powder for silver-coated copper according to claim 4, characterized in that: The assembly slot is also equipped with a power supply. The output end of the temperature control box is fixedly connected to a circulation pump. The output end of the circulation pump is connected to a refrigerant pipeline. Multiple connecting holes are opened on the bottom end face side wall of the ball mill cylinder.

6. The ball milling equipment for producing flake copper powder for silver-coated copper as described in claim 5, characterized in that: The anti-sticking liner assembly includes a liner fixedly installed on the inner wall of the ball mill cylinder. Multiple circumferentially wavy patterns are fixedly installed on the inner wall of the liner. Multiple vertical guide grooves are also distributed at equal angles on the inner wall of the liner. Multiple concave-convex dot arrays are also provided on the inner wall of the liner.

7. The ball milling equipment for producing flake copper powder for silver-coated copper as described in claim 6, characterized in that: The floating scraper assembly includes a hollow support cylinder fixedly installed on the drive shaft wall, a spring installed inside the hollow support cylinder, and a support column slidably installed at the front end inside the hollow support cylinder.

8. The ball milling equipment for producing flake copper powder for silver-coated copper according to claim 7, characterized in that: A scraper is fixedly installed at the other end of the supporting slide column, and multiple bouncing balls are installed on the scraper.

9. A ball milling apparatus for producing flake copper powder for silver-coated copper as described in claim 8, characterized in that: The ball mill cylinder contains multiple grinding balls. The upper end of the ball mill cylinder is fixedly connected to a feed valve pipe, and the bottom side wall of the ball mill cylinder is fixedly connected to a discharge valve pipe.

10. A method of using a ball milling apparatus for producing flake copper powder for silver-coated copper as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Feeding preparation: Open the feed valve pipe at the top of the ball mill cylinder, and put spherical copper powder, wet grinding media and grinding balls into the ball mill cylinder according to the preset ratio. After feeding is completed, close the feed valve pipe to ensure that the cylinder is sealed. S2. Equipment Start-up: The drive assembly and temperature control assembly are started simultaneously. The drive motor drives the transmission shaft and various stirring and scraping components to rotate via the reducer. The temperature control assembly starts the refrigeration and refrigerant circulation to regulate the temperature inside the cylinder to 30-40℃. S3. Grinding operation: During equipment operation, the stirring and dispersing disc, the gradient guide cylinder, and the bottom stirring head work together to achieve forced circulation and uniform grinding of the slurry. The floating scraping component cleans the cylinder wall simultaneously to prevent powder from adhering to the wall and agglomerating. Grinding continues until the flaky copper powder reaches the preset diameter-to-thickness ratio requirement. S4. Stop and discharge: After the preset grinding time is reached, turn off the drive motor and temperature control components. After the equipment stops and the pressure inside the cylinder returns to normal, open the discharge valve at the bottom of the cylinder to discharge the ground flaky copper powder slurry, thus completing one operation.

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