Rubber magnetic code disc, preparation method thereof and high-precision magnetic encoder

Abstract

The invention provides a rubber magnetic coded disc, a preparation method thereof and a high-precision magnetic encoder. The preparation method comprises the following steps: banburying and mixing rubber and magnetic powder to obtain rubber magnetic particles; the rubber magnetic particles are subjected to smashing and first rolling, then sheet layer stacking and magnetizing are conducted, and a magnetized rubber magnetic sheet is obtained; and carrying out magnetic direction rearrangement on the magnetized rubber magnetic sheet, then carrying out second rolling and cutting to reduce the width of a magnetic pole, and then assembling the cut sheet to obtain the rubber magnetic code disc. According to the method, a precise magnetizing process is not needed, rubber and magnetic powder are adopted as raw materials, calendaring, overlapping and magnetizing are firstly carried out, and then calendaring, cutting and assembling are carried out to obtain the rubber magnetic code disc. The rubber magnetic coded disc is high in magnetic performance, can stably realize precise magnetization with the unipolar magnetic field width of 0.1-0.5 mm, and has wide application prospects in the fields of robots, automatic driving, industrial machine tools, semiconductor processing equipment, medical instruments, military industry and the like.

Description

Technical Field

[0001] The invention belongs to the field of magnetic encoders and magnetic materials, and in particular relates to a rubber magnetic code disk and a preparation method thereof, and a high-precision magnetic encoder. Background Art

[0002] Magnetic encoders refer to sensors that convert changes in the magnetic properties of magnetic devices into electrical signals to detect corresponding physical quantities. They have been gradually used on a large scale in recent years. It is mainly to install a magnet on the motor shaft, which rotates with the motor shaft, and then install a circuit board on the rear end cover. There is a magnetic field sensing chip in the middle of the circuit board, which can measure the angular change of the magnetic field, thereby determining the rotation angle and angular velocity of the motor shaft. Usually, the magnetic encoder is mainly composed of three parts: the magnetic code disk, the Hall probe and the control software. The magnetic field signal provided by the magnetic code disk directly affects the accuracy of the magnetic sensor and is the core component. With the development of society, the fields of robots, autonomous driving, industrial machine tools, semiconductor processing equipment, medical instruments, military industry, etc. have higher and higher requirements for the accuracy of magnetic encoders, requiring the number of N and S poles on the magnetic code disk to increase and the width of the monopolar magnetic field to decrease. At the same time, the magnetic field strength needs to be kept within an appropriate range.

[0003] When the width of the unipolar magnetic field is more than 2mm, a special magnetizing fixture is often used for magnetization. When the width of the unipolar magnetic field is less than 2mm, a special magnetizing head is often used for magnetization, and it is usually impossible to magnetize to saturation. Germany and Japan are able to produce precision magnetic code disks with a unipolar magnetic field width of 0.1-0.5mm. The material of the code disk is a special alloy, and the magnetic field strength of the magnetic code disk is very small. It needs to be used with a high-precision magnetic field probe. The price is extremely expensive, and some precision magnetizing machines and high-precision magnetic encoders are restricted from export. The domestic method of precision magnetization is mainly to follow foreign countries, develop magnetizing heads with high magnetic field strength, and develop magnetic materials that are easy to magnetize for code disks. However, it is still impossible to stably achieve 0.1-0.5mm precision magnetization. The above methods have encountered bottlenecks and difficulties that are difficult to overcome in a short time.

[0004] Therefore, there is an urgent need to provide a method for preparing a magnetic code disk to solve the problem of magnetizing the magnetic code disk for a high-precision encoder. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a rubber magnetic code disk and a preparation method thereof and a high-precision magnetic encoder. The present invention does not require a precise magnetization process, but uses rubber and magnetic powder as raw materials, first calendering, stacking and magnetizing, and then calendering and cutting to assemble a rubber magnetic code disk. The rubber magnetic code disk prepared by this process has high magnetic properties and can stably achieve precise magnetization with a monopole magnetic field width of 0.1-0.5mm. The rubber magnetic code disk has broad application prospects in the fields of robots, autonomous driving, industrial machine tools, semiconductor processing equipment, medical instruments, military industry, etc.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a rubber magnetic code disk, the preparation method comprising the following steps:

[0008] The rubber and magnetic powder are mixed by kneading to obtain rubber magnetic particles.

[0009] The rubber magnetic particles are crushed and first calendered, and then the sheets are stacked and magnetized to obtain the magnetized rubber magnetic sheet.

[0010] The magnetized rubber magnetic sheet is subjected to magnetic rearrangement, and then subjected to a second calendering and cutting, and then the cut sheets are assembled to obtain the rubber magnetic code disk.

[0011] The present invention does not require a precise magnetization process, but uses rubber and magnetic powder as raw materials, first calendering, stacking and magnetizing, and then calendering and cutting to assemble a rubber magnetic code disk. The rubber magnetic code disk prepared by this process has high magnetic properties and can stably achieve precise magnetization with a monopole magnetic field width of 0.1-0.5mm. The rubber magnetic code disk has broad application prospects in the fields of robots, autonomous driving, industrial machine tools, semiconductor processing equipment, medical instruments, military industry, etc.

[0012] It should be noted that the purpose of the second calendering and cutting is to reduce the thickness (also the magnetic pole width) of the rubber magnetic sheet.

[0013] Preferably, an auxiliary agent is added during the kneading and mixing of the rubber and the magnetic powder.

[0014] In the present invention, the role of introducing the auxiliary agent is to improve the processability, uniformity and aging resistance of the material.

[0015] Preferably, the rubber includes any one of polyvinyl chloride, chlorinated polyethylene, nitrile rubber or ethylene-vinyl acetate copolymer, or a combination of at least two thereof.

[0016] Preferably, the magnetic powder includes any one of strontium ferrite magnetic powder, barium ferrite magnetic powder, neodymium iron boron magnetic powder or samarium iron nitrogen magnetic powder, or a combination of at least two of them.

[0017] Preferably, the auxiliary agent includes any one or a combination of at least two of stearic acid, stearic acid derivatives, plasticizers, antioxidants, coupling agents or vulcanizing agents. Exemplarily, the plasticizers may be phthalates, epoxy soybean oil, citrates, etc., the antioxidants may be antioxidants RD, antioxidants 4010, antioxidants ODA, etc., the coupling agents may be titanates, aluminates, silane coupling agents, etc., and the vulcanizing agents may be sulfur, DCP, BIPB, etc.

[0018] Preferably, based on the total mass of the rubber, magnetic powder and additives, the mass fraction of the magnetic powder is 80-95%, for example, 80%, 85%, 90% or 95%, the mass fraction of the rubber is 5-20%, for example, 5%, 10%, 15% or 20%, and the mass fraction of the additive is 0-5%, for example, 1%, 2%, 3%, 4% or 5%.

[0019] In the present invention, a suitable content of rubber, a suitable content of auxiliary agent and a certain mass fraction of magnetic powder can more effectively exert the synergistic effect of the three, promote the uniform distribution of the magnetic powder and improve the mechanical properties of the rubber.

[0020] Preferably, the temperature of the banburying and mixing is 100-150°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

[0021] In the present invention, the internal mixing process at an appropriate temperature is helpful to improve the processing performance of the rubber and prevent the premature vulcanization of the rubber.

[0022] Preferably, the mixing time is 20-80 min, for example, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min or 80 min.

[0023] Preferably, the particle size of the rubber magnetic powder obtained after the pulverization is ≤0.3 mm, for example, it can be 0.3 mm, 0.2 mm, 0.1 mm or 0.05 mm.

[0024] In the present invention, the particle size of the rubber magnetic powder obtained after pulverization is controlled to be ≤0.3 mm, which helps to prevent the magnetic powder from agglomerating and improve the uniformity of the magnetic powder distribution.

[0025] Preferably, the thickness of the sheet after the first calendering is 0.1-1 mm, for example, it can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm or 1 mm.

[0026] Preferably, before the sheets are stacked, an adhesive layer is first coated on the surface of each sheet.

[0027] In the present invention, the purpose of coating the adhesive layer is to improve the uniformity of the secondary calendering and prevent the magnetic sheet from being delaminated.

[0028] Preferably, the thickness of the adhesive layer is 0.001-0.05 mm, for example, it may be 0.001 mm, 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm or 0.05 mm.

[0029] In the present invention, an appropriate thickness of the bonding layer helps to maintain good bonding between the magnetic sheets. If the thickness is too large, it is not conducive to the control of the magnetic pole width and is also prone to glue flow.

[0030] Preferably, the material of the adhesive layer includes any one of polyvinyl chloride, chlorinated polyethylene, nitrile rubber, toughened epoxy resin or acrylic pressure-sensitive adhesive, or a combination of at least two thereof.

[0031] Preferably, the magnetization direction is plane penetration magnetization or side penetration magnetization.

[0032] Preferably, the specific method of magnetic rearrangement includes:

[0033] According to the target requirements, the N pole of each magnetic sheet is arranged to attract the S pole of the adjacent magnetic sheet, or the N pole of each magnetic sheet is arranged to repel the N pole of the adjacent magnetic sheet. For example, it is in the form of NSNSNS, or NSSNNSSN (a single magnetic sheet is NS pole).

[0034] Preferably, the assembled shape is a hollow cylinder.

[0035] Preferably, the thickness of the sheet after the second calendering is 0.1-100 mm, for example, 0.1 mm, 1 mm, 10 mm, 30 mm, 50 mm, 70 mm or 90 mm, etc., and the length and width of the sheet after cutting are independently 2-200 mm, for example, 2 mm, 10 mm, 50 mm, 100 mm, 150 mm or 120 mm, etc. Preferably, the sheet thickness surface formed after the second calendering has a trapezoidal structure.

[0036] Preferably, the preparation method comprises the following steps:

[0037] (1) Rubber, magnetic powder and additives are mixed at 100-150° C. for 20-80 minutes to obtain rubber magnetic particles.

[0038] Wherein, based on the total mass of the rubber, magnetic powder and additives, the mass fraction of the magnetic powder is 80-95%, the mass fraction of the rubber is 5-20%, and the mass fraction of the additive is 0-5%.

[0039] (2) The rubber magnetic particles are crushed into rubber magnetic powder with a particle size of ≤0.3 mm, and then first calendered to a sheet thickness of 0.1-1 mm, and then glue is coated on the surface of the calendered sheet to form a bonding layer with a thickness of 0.001-0.05 mm, and then cut to obtain 2-2000 pieces (for example, 2 pieces, 10 pieces, 100 pieces, 500 pieces, 1000 pieces, 1500 pieces or 2000 pieces, etc.) of rubber magnetic sheets, and then the sheets are stacked and magnetized in the direction of plane penetration magnetization or side penetration magnetization to obtain magnetized rubber magnetic sheets.

[0040] (3) The magnetized rubber magnetic sheets are magnetically rearranged, that is, the N-end of each magnetic sheet is arranged to attract the S-end of the adjacent magnetic sheet, or the N-end of each magnetic sheet is arranged to repel the N-end of the adjacent magnetic sheet, so as to obtain a rubber magnetic sheet with a specific magnetic field.

[0041] Then, a second calendering is performed to a sheet thickness of 0.1-100 mm, and the sheet is cut to a length and a width of 2-200 mm independently, and then the cut sheets are assembled into a hollow cylinder, and the rubber magnetic code disk of a specific thickness is cut.

[0042] In a second aspect, the present invention provides a rubber magnetic code disk, which is prepared by the preparation method described in the first aspect.

[0043] The monopole magnetic field width of the rubber magnetic code disk is 0.1-0.5 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0044] In a third aspect, the present invention provides a high-precision magnetic encoder, wherein the high-precision magnetic encoder comprises the rubber magnetic code disk as described in the second aspect.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention does not require a precise magnetization process, but uses rubber and magnetic powder as raw materials, first calendering, stacking and magnetizing, and then calendering and cutting to assemble a rubber magnetic code disk. The rubber magnetic code disk prepared by this process has high magnetic properties and can stably achieve precise magnetization with a monopole magnetic field width of 0.1-0.5mm. The rubber magnetic code disk has broad application prospects in the fields of robots, autonomous driving, industrial machine tools, semiconductor processing equipment, medical instruments, military industry, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of the method for preparing the rubber magnetic code disk provided in Example 1 of the present invention.

[0049] Figure 2 This is a schematic diagram of a rubber magnetic code disk provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing a rubber magnetic code disk, and its flow chart is as follows: Figure 1 As shown, the preparation method comprises the following steps:

[0053] (1) 9 kg of chlorinated polyethylene, 90 kg of strontium ferrite magnetic powder, 0.5 kg of plasticizer, 0.25 kg of coupling agent and 0.25 kg of calcium stearate were added to an internal mixer and mixed at 145° C. for 30 minutes to obtain rubber magnetic particles.

[0054] Among them, based on the total mass of the chlorinated polyethylene, strontium ferrite magnetic powder, plasticizer, coupling agent and calcium stearate, the mass fraction of the strontium ferrite magnetic powder is 90%, the mass fraction of the chlorinated polyethylene is 9%, the total mass fraction of the plasticizer, coupling agent and calcium stearate is 1%, the plasticizer is diisononyl phthalate, and the coupling agent is a titanate coupling agent.

[0055] (2) The rubber magnetic particles are crushed into rubber magnetic powder with a particle size of less than 0.15 mm, and then a calender is used to perform a first calendering to a sheet thickness of 0.4 mm. An acrylic pressure-sensitive adhesive is then coated on the surface of the calendered sheet to form a bonding layer with a thickness of 0.005 mm. The sheet is then cut into 10 rubber magnetic sheets with a size of 130 mm × 30 mm × 0.405 mm. The sheets are then stacked and magnetized in the direction of plane penetration magnetization to obtain magnetized rubber magnetic sheets.

[0056] (3) The magnetized rubber magnetic sheets are magnetically rearranged to form rubber magnetic sheets with a magnetic field in the form of NSSNNSSN (the magnetic sheets repel each other).

[0057] Then a calender is used for the second calendering to the rubber magnetic sheet thickness of 1mm (the thickness of a single magnetic sheet is thinned to 0.1mm), and it is cut to a size of 70mm×6mm×1mm. Subsequently, the 314 cut sheets are assembled into a hollow cylinder with a height of 70mm, an inner circle radius of 50mm, and an outer diameter of 56mm. After being firmly fixed, the rubber magnetic code disk ring with a thickness of 3mm is cut.

[0058] Example 2

[0059] This embodiment provides a method for preparing a rubber magnetic code disk, and the preparation method comprises the following steps:

[0060] (1) 11 kg of chlorinated polyethylene, 88 kg of strontium ferrite magnetic powder, 0.5 kg of plasticizer, 0.25 kg of coupling agent and 0.25 kg of calcium stearate were added to an internal mixer and mixed at 145° C. for 30 minutes to obtain rubber magnetic particles.

[0061] Among them, based on the total mass of the chlorinated polyethylene, strontium ferrite magnetic powder, plasticizer, coupling agent and calcium stearate, the mass fraction of the strontium ferrite magnetic powder is 88%, the mass fraction of the chlorinated polyethylene is 11%, the total mass fraction of the plasticizer, coupling agent and calcium stearate is 1%, the plasticizer is epoxidized soybean oil, and the coupling agent is a silane coupling agent.

[0062] (2) The rubber magnetic particles are crushed into rubber magnetic powder with a particle size of less than 0.15 mm, and then a calender is used to perform a first calendering to a sheet thickness of 0.2 mm. Chlorinated polyethylene glue is then coated on the surface of the calendered sheet to form a bonding layer with a thickness of 0.005 mm. The sheet is then cut into 100 rubber magnetic sheets with a size of 130 mm × 30 mm × 0.205 mm. The sheets are then stacked and magnetized in the direction of plane penetration magnetization to obtain magnetized rubber magnetic sheets.

[0063] (3) The magnetized rubber magnetic sheets are magnetically rearranged to form rubber magnetic sheets with a magnetic field in the form of NSSNNSSN (the magnetic sheets repel each other).

[0064] Then, a calender is used to calender the rearranged 100 rubber magnetic sheets into a trapezoidal structure with one side thick and the other side thin (the thickness of the sheet formed after the second calendering), with an average thickness of 10 mm in the middle, and then cut to obtain 36 trapezoidal structures with a bottom side length of 11.74 mm, a top side length of 8.25 mm, a waist height of 20 mm, and a length of 30 mm. Subsequently, the 36 trapezoidal structures are assembled into a circular ring with an inner diameter of 47.3 mm and an outer diameter of 67.3 mm. After being firmly fixed, the rubber magnetic code disk with a thickness of 3 mm is cut. Figure 2 A schematic diagram of the rubber magnetic code disk is shown.

[0065] Example 3

[0066] This embodiment provides a method for preparing a rubber magnetic code disk, and the preparation method comprises the following steps:

[0067] (1) 7.5 kg of nitrile rubber, 92 kg of NdFeB magnetic powder, 0.25 kg of plasticizer and 0.25 kg of calcium stearate were added to an internal mixer and mixed at 145° C. for 30 min to obtain rubber magnetic particles.

[0068] Among them, based on the total mass of the nitrile rubber, NdFeB magnetic powder, plasticizer, coupling agent and calcium stearate, the mass fraction of the NdFeB magnetic powder is 90%, the mass fraction of the nitrile rubber is 9%, the total mass fraction of the plasticizer, coupling agent and calcium stearate is 1%, the plasticizer is acetyl tri-n-butyl citrate, and the coupling agent is aluminate.

[0069] (2) The rubber magnetic particles are crushed into rubber magnetic powder with a particle size of ≤0.3 mm, and then a calender is used to perform a first calendering to a sheet thickness of 1 mm, and then liquid nitrile rubber is coated on the surface of the calendered sheet to form a bonding layer with a thickness of 0.01 mm, and then the sheet is cut into 10 rubber magnetic sheets with a size of 130 mm×30 mm×1.01 mm, and then the sheets are stacked and magnetized in the direction of side penetration magnetization to obtain a magnetized rubber magnetic sheet.

[0070] (3) The magnetized rubber magnetic sheets are magnetically rearranged to form rubber magnetic sheets with NSNS magnetic field (the magnetic sheets attract each other).

[0071] Then a calender is used for the second calendering until the rubber magnetic sheet has a thickness of 1 mm, and then it is cut into sheets with a size of 70 mm × 6 mm × 1 mm. Subsequently, 314 cut sheets are assembled into a hollow cylinder with a height of 70 mm, an inner circle radius of 50 mm, and an outer diameter of 56 mm. After being firmly fixed, a rubber magnetic code disk with a thickness of 2 mm is cut.

[0072] Example 4

[0073] The difference between this embodiment and embodiment 1 is that in step (1), the amount of plasticizer added is 2.5 kg, the amount of coupling agent added is 1.5 kg, the amount of calcium stearate added is 1.5 kg, and the amount of strontium ferrite magnetic powder added is adaptively adjusted to 85.5 kg, so that the total mass of chlorinated polyethylene, strontium ferrite magnetic powder, plasticizer, coupling agent and calcium stearate is 100 kg.

[0074] The rest of the preparation methods and parameters were the same as those in Example 1.

[0075] Example 5

[0076] The difference between this embodiment and embodiment 1 is that in step (1), the amount of chlorinated polyethylene added is 25 kg, and the amount of strontium ferrite magnetic powder added is adaptively adjusted to 74 kg.

[0077] The rest of the preparation methods and parameters were the same as those in Example 1.

[0078] Example 6

[0079] The difference between this embodiment and embodiment 1 is that the chlorinated polyethylene in step (1) is replaced by polyethylene.

[0080] The rest of the preparation methods and parameters were the same as those in Example 1.

[0081] Example 7

[0082] The difference between this embodiment and embodiment 1 is that the adhesive layer is not applied in step (2).

[0083] The rest of the preparation methods and parameters were the same as those in Example 1.

[0084] Example 8

[0085] The difference between this embodiment and embodiment 1 is that no magnetic rearrangement is performed in step (3).

[0086] The rest of the preparation methods and parameters were the same as those in Example 1.

[0087] Example 9

[0088] The difference between this embodiment and embodiment 1 is that the thickness of the first calendering layer in step (2) is changed to 1 mm, and the number of stacked layers is changed to 5.

[0089] The rest of the preparation methods and parameters were the same as those in Example 1.

[0090] Comparative Example 1

[0091] This comparative example provides a method for preparing a rubber magnetic code disk, and the preparation method comprises the following steps:

[0092] (1) 9 kg of chlorinated polyethylene, 90 kg of strontium ferrite magnetic powder, and 1 kg of stearic acid were added to an internal mixer and mixed at 120° C. for 30 min to obtain rubber magnetic particles.

[0093] (2) The rubber magnetic particles are crushed into rubber magnetic particles with a particle size of 1 mm, and then rolled using a calender to obtain a rubber magnetic sheet with a thickness of 3 mm. The rubber magnetic sheet is then cut into rings with an inner diameter of 50 mm and an outer diameter of 56 mm.

[0094] (3) Use double-sided tape to stick the rubber magnetic code disk prepared in step (2) on an iron ring (bottom plate) of the same size, ensure that the magnetic ring is flat, and then place it on the magnetizer, set the magnetization spacing to 0.8mm (currently the magnetizer cannot achieve a narrower spacing), and rotate it for one circle to obtain the rubber magnetic code disk. Performance test

[0095] The rubber magnetic code disks provided in the above embodiments and comparative examples were tested for average pole width and average magnetic field strength.

[0096] The test conditions are as follows: Use double-sided tape to stick the rubber magnetic code disk on an iron ring (bottom plate) of the same size, ensure that the magnetic ring is flat, and then place it on a surface magnetic tester to test the surface magnetic properties of the rubber magnetic code disk in a circle at the center of the code track. The height of the test probe from the rubber magnetic code disk is 0.01mm.

[0097] The test results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] analyze:

[0102] As can be seen from the above table, the present invention does not require a precise magnetization process, but uses rubber and magnetic powder as raw materials, first calendering, stacking and magnetizing, and then calendering and cutting to assemble a rubber magnetic code disk. The rubber magnetic code disk prepared by this process has high magnetic properties and can stably achieve precise magnetization with a monopole magnetic field width of 0.1-0.5mm.

[0103] It can be seen from Examples 1 and 4 that if an excessive amount of additives is added, the magnetic sheet will be too soft and the magnetic properties will be reduced.

[0104] It can be seen from Examples 1 and 5 that if the amount of rubber used is too high, the magnetic sheet will be soft and the magnetic properties will decrease.

[0105] It can be seen from Example 1 and Example 6 that if the chlorinated polyethylene rubber is replaced by polyethylene plastic, the polyethylene is too hard, the adhesion between the magnetic powders is poor, and the calendering process cannot be performed at room temperature.

[0106] It can be seen from Example 1 and Example 7 that if the adhesive layer is not coated, the magnetic properties of the magnetic ring surface are improved, but the bonding between the magnetic sheets is not tight, and there is a risk of cracking.

[0107] It can be seen from Example 1 and Example 8 that if magnetic direction rearrangement is not performed, the required precise magnetic field cannot be formed.

[0108] It can be seen from Example 1 and Example 9 that if the thickness of a single magnetic sheet and the number of stacked layers are changed, rubber magnetic code disks with different magnetic pole widths and magnetic field strengths can be formed.

[0109] It can be seen from Example 1 and Comparative Example 1 that the current domestic magnetizers cannot achieve precise magnetization with a pole width of 0.1-0.5 mm, and the magnetization magnetic field intensity is low and cannot be magnetized to saturation. Compared with the preparation method provided in Comparative Example 1, the present application is simpler, does not require a precise magnetizer, and can prepare rubber magnetic code disks with higher precision and higher magnetic field intensity.

[0110] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a rubber magnetic code disk, characterized in that: The preparation method comprises the following steps: The rubber and magnetic powder are mixed by kneading to obtain rubber magnetic particles; The rubber magnetic particles are crushed and first calendered, and then the sheets are stacked and magnetized to obtain a magnetized rubber magnetic sheet; The magnetized rubber magnetic sheet is subjected to magnetic rearrangement, and then subjected to a second calendering and cutting, and then the cut sheets are assembled to obtain the rubber magnetic code disk.

2. The preparation method according to claim 1, characterized in that: During the mixing of the rubber and the magnetic powder, an auxiliary agent is added; Preferably, the rubber includes any one of polyvinyl chloride, chlorinated polyethylene, nitrile rubber or ethylene-vinyl acetate copolymer or a combination of at least two thereof; Preferably, the magnetic powder includes any one of strontium ferrite magnetic powder, barium ferrite magnetic powder, neodymium iron boron magnetic powder or samarium iron nitrogen magnetic powder, or a combination of at least two thereof; Preferably, the auxiliary agent includes any one or a combination of at least two of stearic acid, stearic acid derivatives, plasticizers, anti-aging agents, coupling agents or vulcanizing agents; Preferably, based on the total mass of the rubber, magnetic powder and additives, the mass fraction of the magnetic powder is 80-95%, the mass fraction of the rubber is 5-20%, and the mass fraction of the additive is 0-5%.

3. The preparation method according to claim 1 or 2, characterized in that: The mixing temperature is 100-150°C; Preferably, the mixing time is 20-80 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that The particle size of the rubber magnetic powder obtained after the pulverization is ≤0.3mm; Preferably, the thickness of the sheet after the first calendering is 0.1-1 mm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: Before the sheets are stacked, a bonding layer is first applied on the surface of each sheet; Preferably, the thickness of the adhesive layer is 0.001-0.05 mm; Preferably, the material of the adhesive layer includes any one or a combination of at least two of polyvinyl chloride, chlorinated polyethylene, nitrile rubber, toughened epoxy resin or acrylic pressure-sensitive adhesive; Preferably, the magnetization direction is plane penetration magnetization or side penetration magnetization.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The specific method of magnetic rearrangement includes: According to target requirements, the N-end of each magnetic sheet is arranged to attract the S-end of the adjacent magnetic sheet, or the N-end of each magnetic sheet is arranged to repel the N-end of the adjacent magnetic sheet.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The shape after assembly is a hollow cylinder; Preferably, the thickness of the sheet after the second calendering is 0.1-100 mm, and the length and width of the sheet after cutting are independently 2-200 mm.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) kneading and mixing the rubber, magnetic powder and additives at 100-150° C. for 20-80 min to obtain rubber magnetic particles; Wherein, based on the total mass of the rubber, magnetic powder and additives, the mass fraction of the magnetic powder is 80-95%, the mass fraction of the rubber is 5-20%, and the mass fraction of the additive is 0-5%; (2) crushing the rubber magnetic particles into rubber magnetic powder with a particle size of ≤0.3 mm, and then first calendering the sheet to a thickness of 0.1-1 mm, and then coating the surface of the calendered sheet with glue to form a bonding layer with a thickness of 0.001-0.05 mm, and then cutting to obtain 2-2000 rubber magnetic sheets, and then stacking the sheets and magnetizing them in the direction of plane penetration magnetization or side penetration magnetization to obtain magnetized rubber magnetic sheets; (3) magnetically rearranging the magnetized rubber magnetic sheets, that is, arranging the N-end of each magnetic sheet to attract the S-end of the adjacent magnetic sheet, or arranging the N-end of each magnetic sheet to repel the N-end of the adjacent magnetic sheet, to obtain a rubber magnetic sheet with a specific magnetic field; Then, a second calendering is performed to a sheet thickness of 0.1-100 mm, and the sheet is cut to a length and a width of 2-200 mm independently, and then the cut sheets are assembled into a hollow cylinder, and the rubber magnetic code disk of a specific thickness is cut.

9. A rubber magnetic code disk, characterized in that: The rubber magnetic code disk is prepared by the preparation method according to any one of claims 1 to 8; The monopole magnetic field width of the rubber magnetic code disk is 0.1-0.5 mm.

10. A high-precision magnetic encoder, characterized in that: The high-precision magnetic encoder comprises the rubber magnetic code disk as claimed in claim 9.

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