Method for sampling magnetic substance particles
By using magnetic pickup and transparent tape, the problem of magnetic particle detection in lithium-ion battery production is solved, and the rapid and accurate magnetic particle detection is achieved without shutdown, improving the quality of battery products.
Patent Information
- Application Number
- CN202510021961.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-05-09
AI Technical Summary
The prior art cannot identify and test magnetic particles on the surfaces of pole sheets, cores and other surfaces in the production process of lithium-ion batteries in a timely and efficient manner, resulting in the impact of battery product quality.
Magnetic pickups are used to flexibly absorb magnetic particles and transfer them to detect them with transparent tape. There is no need to shut down, and the magnetic particles at the time of product production can be obtained.
It can quickly and accurately obtain magnetic particles on the surface of the product without shutdown, shorten the testing time and resource costs, and provide timely feedback to guide on-site inspections and improvements.
Smart Images
Figure CN119958907A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of lithium ion battery production, and in particular relates to a magnetic particle sampling method. Background Art
[0002] During the production process of lithium-ion batteries, magnetic particles are generated due to excessive environmental dust or wear of moving parts of equipment. These magnetic particles are sputtered onto the surface of the pole piece. After winding to make the core, the magnetic particles will pierce the core membrane and cause internal short circuit failure; or after being assembled into a lithium-ion battery, the magnetic particles are oxidized at the positive electrode and then reduced and precipitated at the negative electrode during the battery charging and discharging process. The formed metal dendrites pierce the membrane and cause positive and negative short circuit failure, which may cause thermal runaway of the battery cell in severe cases. Therefore, timely identification of the presence of magnetic particles on the surface of pole pieces, cores, etc. is particularly important for the quality of battery products. At present, the industry sets magnetic bars through key processes to adsorb magnetic particles generated in the production process, and regularly samples and tests the magnetic substances on the surface of the magnetic bars. This sampling method has the following defects: on the one hand, sampling needs to be carried out when the production equipment is shut down, and the magnetic bars are disassembled; on the other hand, the adsorbents on the surface of the magnetic bars are accumulated over a long period of time, which cannot effectively reflect the severity of the magnetic particle contamination on the surface of the product at that time, and the number of adsorbents on the magnetic bars is large, the test cycle is long, and timely feedback cannot be given to guide on-site investigation and improvement. Therefore, it is necessary to develop a timely and effective method for testing magnetic particles on the surface of products. Summary of the invention
[0003] The present invention provides a magnetic particle sampling method. Under the premise of originally setting a magnetic rod, the magnetic particles are flexibly adsorbed by a magnetic picker and transferred for detection by a transparent tape, without stopping the machine, and the magnetic particle situation at the time of product production can be obtained.
[0004] The technical solution adopted by the present invention is: A magnetic particle sampling method, the steps are as follows, Prepare sampling tools: The sampling tools include a magnetic pickup, a transparent slide and transparent tape; the magnetic pickup is a telescopic magnetic pickup purchased on the market, such as SATA 11924, and the transparent slide can be made of transparent glass or transparent plastic plate, which is mainly used as a slide for subsequent microscope inspection. The high transparency does not affect the observation under the microscope; the transparent tape can stick and absorb magnetic particles on the one hand, and does not affect the observation under the microscope on the other hand.
[0005] Clean the magnetic pickup and transparent slide: In order to prevent the particles carried by the sampling tool from affecting the actual sampling, the sampling tool needs to be cleaned and kept clean to improve the sampling accuracy of magnetic particles; The magnetic pickup is surface cleaned and deep cleaned. After deep cleaning, protective tape is left on the magnetic suction part of the magnetic pickup. The protective tape is to ensure the cleanliness of the magnetic pickup and avoid residual magnetic particles in the magnetic suction part, which will affect subsequent sampling and testing. Clean the surface of the transparent slide, and then stick some transparent tape on the transparent slide to protect the position. When sampling, multi-point sampling or multiple sampling at one point is generally performed. In order to avoid the influence of external magnetic particles on the sampling results, the position where the sampling tape is subsequently pasted needs to be protected to keep the position clean; sampling: The magnetic picker attracts the magnetic particles; Tear off the protective tape of the magnetic part, and make the magnetic part of the magnetic pickup close to the sampling position to absorb the magnetic particles. The distance between the magnetic part and the sampling position is 5mm-15mm, and the sampling time is 20s-30s. After the sampling time is over, move the magnetic pickup away from the sampling position; Get the sampling tape from the magnetic pick-up; Cover the magnetic part of the magnetic pickup with clean transparent tape, and then use hands wearing nitrile gloves to compact the sample, and then draw lines on the transparent tape along the edge of the magnetic part to mark the effective sampling area to obtain the sampling tape; because the side end surface of the magnetic part may also absorb magnetic particles, but only the magnetic particles on the positive end surface of the magnetic part are studied, the transparent tape is marked on the front side of the magnetic part to ensure that the effective sampling area after each sampling is the same; The sampling tape is pasted onto a transparent slide; Tear off the transparent tape on the transparent slide, tear off the sampling tape from the magnetic picker and stick it to the position on the transparent slide where the transparent tape was removed; The magnetic pickup is clean and ready for use.
[0006] As a preferred solution of the present invention, the transparent tape is a 3M high-transparency tape, such as Scotch 600-CQ33.
[0007] As a preferred solution of the present invention, the magnetic flux of the magnetic pickup is not less than 5000Gs; the thickness of the transparent slide is 0.2mm-0.5mm, and the size of the transparent slide can be the size of A4 paper.
[0008] As a preferred solution of the present invention, the cleaning process of the magnetic pickup is: firstly, the magnetic pickup is fully cleaned with dust-free paper and alcohol; Then use a piece of transparent tape to stick and remove the magnetic part of the magnetic pickup to complete a deep cleaning; Repeat deep cleaning 2-3 times, and do not remove the transparent tape from the last deep cleaning as a protective tape for the magnetic part. The purpose of deep cleaning is to remove as much residual particles as possible on the surface of the magnetic part.
[0009] As a preferred solution of the present invention, the position protection of the transparent slide is to stick several sections of transparent tape on the surface of the transparent slide; the length of each section of transparent tape can completely cover the magnetic suction part; and the number of transparent tapes is not less than the sampling points, and the transparent slide is cleaned by wiping with dust-free paper and alcohol.
[0010] As a preferred solution of the present invention, the transparent slide is a transparent PVC soft rubber board. The higher the transparency of the transparent PVC soft rubber board, the better. It can be directly purchased and used.
[0011] As a preferred embodiment of the present invention, when tearing off the protective tape of the magnetic attraction part, wear nitrile gloves, and after tearing off the protective tape, avoid the magnetic attraction part from contacting hands and other objects to keep it clean and avoid contamination of the magnetic attraction part.
[0012] As a preferred solution of the present invention, after the sampling tape is attached to the transparent slide, a mark is made on the transparent slide to record the sampling information.
[0013] As a preferred embodiment of the present invention, the transparent slide with the sampling tape is tested under a microscope, and the microscope analyzes the magnetic particles in the effective sampling area of each sampling tape. The detection process is to place the sample identification area under a microscope and first use 200 times to find metallic luster particles (metallic luster is determined to be metal) or other granular foreign matter, then magnify it to 500 times, measure the particle size with a ruler and mark and save it, and summarize the number of particles <50um, 50um≤particles <100um, 100um≤particles <150, 150um≤particles, summarize and record the test results, and divide them into three grades according to the test results: Grade 3: There are obvious metal or large foreign matter (>100um); Grade 2: There are multiple small foreign matter or it cannot be clearly distinguished whether it is metal; Grade 1: There are three or less non-metallic foreign matter.
[0014] Compared with the traditional magnetic rod sampling method, the present invention is simple and convenient to operate, does not require downtime, greatly shortens the time and resource costs, and is versatile and highly accurate. Sampling and analysis can be performed at any time without being restricted by time and space, and does not affect the normal production of the production line. It can also be used as a supplement to inspect whether the magnetic rods of on-site equipment have failed. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0016] Figure 1 This is a microscope photo of the sampling tape of magnetic particles on the surface of aluminum foil before positive electrode coating.
[0017] Figure 2 This is a microscope photo of the sampling tape of magnetic particles on the surface of the pole piece after positive electrode coating. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] Example: A magnetic particle sampling method, the steps are as follows, Prepare sampling tools: The sampling tools include a magnetic pickup, a transparent slide and a transparent tape; the magnetic pickup is a telescopic magnetic pickup purchased from the market, and the magnetic flux of the magnetic pickup is not less than 5000Gs, such as Star 11924. The transparent slide can use transparent glass or transparent plastic plate. This embodiment uses a transparent PVC soft rubber board. The higher the transparency of the transparent PVC soft rubber board, the better. You can directly buy and use it, such as Dongling high-transparency PVC board. And the thickness of the transparent slide is 0.2mm-0.5mm, and the size of the transparent slide can be the size of A4 paper. The transparent slide is mainly used as a slide for subsequent microscopic detection, and the high transparency does not affect the observation of the microscope; the transparent tape can stick and adsorb magnetic particles on the one hand, and does not affect the observation of the microscope on the other hand. The transparent tape uses 3M high-transparency tape, such as Scotch 600-CQ33.
[0020] In order to prevent the particles carried by the sampling tool from affecting the actual sampling, the sampling tool needs to be cleaned and kept clean to improve the sampling accuracy of magnetic particles. Therefore, the magnetic pickup and transparent slide are cleaned separately: The magnetic pickup is surface cleaned and deep cleaned. After deep cleaning, protective tape is left on the magnetic suction part of the magnetic pickup. The protective tape is to ensure the cleanliness of the magnetic pickup and avoid residual magnetic particles in the magnetic suction part, which will affect subsequent sampling and testing. Specifically, the cleaning process of the magnetic pickup is as follows: first, clean the magnetic pickup thoroughly with dust-free paper and alcohol; Then use a piece of transparent tape to stick and remove the magnetic part of the magnetic pickup to complete a deep cleaning; Repeat deep cleaning 2-3 times, and do not remove the transparent tape from the last deep cleaning as a protective tape for the magnetic part. The purpose of deep cleaning is to remove as much residual particles as possible on the surface of the magnetic part.
[0021] Wipe the transparent slide with dust-free paper and alcohol to clean the surface. After cleaning, stick several pieces of transparent tape on the transparent slide for position protection. The position protection of the transparent slide is to stick several pieces of transparent tape on the surface of the transparent slide; the length of each piece of transparent tape can completely cover the magnetic suction part, because the transparent tape at this position is occupied by the sampling tape, ensuring that the position where the sampling tape is to be pasted is clean; the number of transparent tapes is not less than the sampling points, because sampling is generally multi-point sampling or multiple sampling at one point, in order to avoid the influence of external magnetic particles on the sampling results, the position where the sampling tape is subsequently pasted needs to be protected to keep the position clean.
[0022] After cleaning, take samples: The magnetic picker attracts the magnetic particles; The operator puts on a nitrile mobile phone in both hands and tears off the protective tape of the magnetic part. During the tearing process, avoid contact between hands and other objects and contamination of the surface of the magnetic part. Make the magnetic part of the magnetic pickup close to the sampling position to absorb magnetic particles. The distance between the magnetic part and the sampling position is 5mm-15mm. The sampling time is 20s-30s. After the sampling time is over, move the magnetic pickup away from the sampling position. Get the sampling tape from the magnetic pick-up; Cover the magnetic part of the magnetic pickup with clean transparent tape, and then use hands wearing nitrile gloves to compact the sample, and then draw lines on the transparent tape along the edge of the magnetic part to mark the effective sampling area to obtain the sampling tape; because the side end surface of the magnetic part may also absorb magnetic particles, but only the magnetic particles on the positive end surface of the magnetic part are studied, the transparent tape is marked on the front side of the magnetic part to ensure that the effective sampling area after each sampling is the same; The sampling tape is pasted onto a transparent slide; Tear off the transparent tape on the transparent slide, tear off the sampling tape from the magnetic pickup and stick it to the transparent slide at the position where the transparent tape was removed, and mark on the transparent slide to record the sampling information.
[0023] The magnetic pickup is cleaned and ready for use. The cleaning process of the magnetic pickup is the same. First, use dust-free paper and alcohol to thoroughly clean the magnetic pickup; Then use a piece of transparent tape to stick and remove the magnetic part of the magnetic pickup to complete a deep cleaning; Repeat deep cleaning 2-3 times, and do not remove the transparent tape from the last deep cleaning as a protective tape for the magnetic part. The purpose of deep cleaning is to remove as much residual particles as possible on the surface of the magnetic part.
[0024] The sampling process is circulated according to the sampling points or the sampling times until the sampling is completed, and the magnetic particles to be detected are obtained by sampling.
[0025] Subsequent detection can be performed using conventional magnetic particle detection methods or using a microscope.
[0026] The detection process is as follows: put the marked area of the sample under a microscope and first use 200 times to look for metallic luster particles (metallic luster is determined to be metal) or other granular foreign matter, then magnify it to 500 times, measure the particle size with a ruler and mark and save it, and summarize the number of particles <50um, 50um≤particles <100um, 100um≤particles <150, 150um≤particles, summarize and record the test results, and divide them into three grades according to the test results: Grade 3: There are obvious metal or large foreign matter (>100um); Grade 2: There are multiple small foreign matter or it cannot be clearly distinguished whether it is metal; Grade 1: There are three or less non-metallic foreign matter.
[0027] After the test, the test result can also be compared with the test result of the magnetic rod to check whether the magnetic rod of the on-site equipment has failed.
[0028] Taking the positive electrode coating workshop as an example, the results of sampling and testing the magnetic particles on the surface of the foil before coating and the pole piece after coating according to the method of the present invention are as follows: Figure 1 As shown, the grade is Grade 3; the sampling tape microscope image of the magnetic particles on the surface of the pole piece after positive electrode coating is as follows Figure 2 As shown, the level is Grade 1.
[0029] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0030] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A magnetic particle sampling method, characterized in that: The steps are as follows, Prepare sampling tools: the sampling tools include a magnetic pick-up, a transparent slide and a transparent tape; Cleaning the magnetic pick-up and transparent slides: The magnetic pickup performs surface cleaning and deep cleaning, and after deep cleaning, protective tape remains on the magnetic suction part of the magnetic pickup; Clean the surface of the transparent slide, and after cleaning, stick some transparent tape on the transparent slide to protect the position; sampling: The magnetic picker attracts magnetic particles; Tear off the protective tape of the magnetic part, and make the magnetic part of the magnetic pickup close to the sampling position to absorb the magnetic particles. The distance between the magnetic part and the sampling position is 5 mm -15 mm, and the sampling time is 20 s -30 s. After the sampling time is over, move the magnetic pickup away from the sampling position. Get the sampling tape from the magnetic pick-up; Cover the magnetic part of the magnetic pickup with clean transparent tape and compact the sample, then draw a line on the transparent tape along the edge of the magnetic part to mark the effective sampling area to obtain the sampling tape; The sampling tape is pasted onto a transparent slide; Tear off the transparent tape on the transparent slide, tear off the sampling tape from the magnetic picker and stick it to the position on the transparent slide where the transparent tape was removed; The magnetic pickup is clean and ready for use.
2. The magnetic particle sampling method according to claim 1, characterized in that: The transparent tape is 3M tape.
3. The magnetic particle sampling method according to claim 1 or 2, characterized in that: The magnetic flux of the magnetic pickup is not less than 5000Gs; the thickness of the transparent slide is 0.2mm-0.5mm.
4. The magnetic particle sampling method according to claim 3, characterized in that: The cleaning process of the magnetic pickup is as follows: first, clean the magnetic pickup thoroughly with dust-free paper and alcohol; Then use a piece of transparent tape to stick and remove the magnetic part of the magnetic pickup to complete a deep cleaning; Repeat 2-3 deep cleanings, and do not remove the transparent tape from the last deep cleaning as a protective tape for the magnetic attraction.
5. The magnetic particle sampling method according to claim 4, characterized in that: The position protection of the transparent slide is to stick several sections of transparent tape on the surface of the transparent slide; the length of each section of transparent tape can completely cover the magnetic attraction part; and the number of transparent tapes is not less than the sampling points.
6. The magnetic particle sampling method according to claim 5, characterized in that: The transparent slide is a transparent PVC soft rubber plate.
7. The magnetic particle sampling method according to claim 3, characterized in that: When tearing off the protective tape on the magnetic part, wear nitrile gloves, and keep the magnetic part clean by avoiding contact with hands and other objects after tearing off the protective tape.
8. The magnetic particle sampling method according to claim 7, characterized in that: After the sampling tape is pasted onto the transparent slide, mark the transparent slide to record the sampling information.
9. The magnetic particle sampling method according to claim 8, characterized in that: The transparent slide to which the sampling tape is attached is inspected under a microscope, and the microscope analyzes the magnetic particles within the effective sampling area of each sampling tape.