Small-angle neodymium iron boron magnetic steel phosphating method

Abstract

The invention discloses a small-angle neodymium-iron-boron magnetic steel phosphating method which comprises the following steps: S1, uniformly dispersing and flatly spreading products on a conveying belt, and carrying out a spraying procedure and an ultrasonic cleaning procedure along with the movement of the conveying belt; s2, the conveying belt conveys the product to enable the product to pass through a novel phosphating solution for a phosphating procedure; s3, the product is conveyed by the conveying belt to be subjected to the spraying procedure again and high-pressure wind shearing; s4, the product is conveyed by the conveying belt to be subjected to the ultrasonic cleaning procedure again and high-pressure wind shearing; and S5, the products are conveyed through the conveying belt to be subjected to the drying procedure and the cooling procedure, and the cooled products are collected and bagged through the conveying belt. According to the invention, the phosphating solution with a certain capability of removing an oxide layer through acid pickling is adopted, so that the conventional oil removal and acid pickling pretreatment procedures are removed in the production, the procedure flow is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of surface treatment of NdFeB, and in particular to a method for phosphating small-angle NdFeB magnetic steel. Background Art

[0002] Compared with nickel plating and zinc plating, phosphating has the advantages of low cost, simple operation and good adhesive properties. It has been widely used in the surface treatment industry of NdFeB magnets, especially in the use of new energy motors.

[0003] There are three common methods for phosphating, namely drum phosphating, manual mesh bag phosphating and hanger phosphating. Among them, drum phosphating and mesh bag phosphating are prone to collisions between products during loading and unloading and rolling and flipping, which can cause corner breakage. Therefore, the angle of the magnetic steel is generally increased to reduce the corner breakage. Hanger phosphating is generally used for large-sized products, which requires more personnel to install and hang, with low efficiency and high cost.

[0004] The traditional phosphating process of NdFeB magnets is: degreasing - water washing - nitric acid pickling - water washing - ultrasonic degreasing - water washing - phosphating - water washing - sealing - unloading. The phosphating process of the existing technology is relatively complicated. At present, with the increasing fluctuations in the price of raw materials for NdFeB, reducing costs is extremely important. Summary of the invention

[0005] In view of the above-mentioned shortcomings, the present invention proposes a method for phosphating small-angle NdFeB magnets. By adopting a phosphating solution with a certain pickling ability to remove the oxide layer, the conventional degreasing and pickling pre-treatment steps are eliminated in production, the process flow is reduced, and the production cost is reduced.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for phosphating small-angle NdFeB magnetic steel, comprising the following steps:

[0007] S1: The product is evenly dispersed and placed on the conveyor belt, and moves with the conveyor belt to the first spraying station for spraying process, and then enters the first ultrasonic cleaning station for ultrasonic cleaning process;

[0008] S2: The conveyor belt transports the product to the phosphating station and the phosphating solution is used for the phosphating process. The phosphating solution includes a solvent and a solute. The solvent is deionized water or distilled water. The solute includes 100-200 g / L phosphoric acid, 20-30 g / L manganese phosphate, 30-50 g / L zinc dihydrogen phosphate, 3-10 g / L cobalt nitrate, 3-9 g / L alkylphenol polyoxyethylene ether, 0.5-1.5 g / L sodium fluoride, 0.2-1.5 g / L tartaric acid, and 2-4 g / L benzotriazole.

[0009] S3: The conveyor belt transports the product to the second spraying station for spraying. After spraying, high-pressure air cutting is performed to blow away part of the phosphating residual liquid remaining on the surface of the product;

[0010] S4: The conveyor belt transports the product to the second ultrasonic cleaning station for ultrasonic cleaning to clean the other part of the phosphating residual liquid on the surface of the product. After the cleaning is completed, high-pressure air cutting is performed to blow away the residual moisture on the surface of the product;

[0011] S5: The conveyor belt transports the product to the drying station for drying process, and then enters the cooling station for cooling process. The cooled product is transported to the receiving and bagging station via the conveyor belt.

[0012] As an improvement, the spraying process of the first spraying station in step S1 uses tap water or pure water for spraying, the water temperature is room temperature, and the spraying time is 10-50 seconds.

[0013] As an improvement, the ultrasonic cleaning process of the first ultrasonic cleaning station in step S1 is performed using tap water or pure water, the water temperature is 40-60° C., and the cleaning time is 2-8 minutes.

[0014] As an improvement, when the phosphating process is performed by using a phosphating solution in step S2, the phosphating solution needs to be prepared first, which specifically includes the following steps:

[0015] S2.1: Prepare the solvent and solute according to the solute and solution ratio of the phosphating solution;

[0016] S2.2: Add 1 / 2 level of solvent into the preparation tank;

[0017] S2.3: Pour the prepared phosphoric acid into the preparation tank and stir to dissolve it completely;

[0018] S2.4: Add the prepared manganese phosphate, zinc dihydrogen phosphate, cobalt nitrate and sodium fluoride into the preparation tank in sequence, and stir to completely dissolve them;

[0019] S2.5: Add the prepared alkylphenol polyoxyethylene ether, tartaric acid and benzotriazole into the preparation tank in sequence, and stir to completely dissolve them;

[0020] S2.6: Pour the remaining solvent into the preparation tank, and then stir evenly to obtain the phosphating solution.

[0021] As an improvement, in the phosphating solution in step S2, alkylphenol polyoxyethylene ether is a surfactant, tartaric acid is a complexing agent, and sodium fluoride is a accelerator.

[0022] As an improvement, in the phosphating process in step S2, the concentration of the phosphating solution is 8 Vol%-20 Vol%, the pH value of the phosphating solution is 1.5-2.5, the phosphating solution phosphates the product at room temperature, and the phosphating time is 5-15 minutes.

[0023] As an improvement, the spraying process of the second spraying station in step S3 uses pure water for spraying, the water temperature is room temperature, and the spraying time is 10-50 seconds.

[0024] As an improvement, the ultrasonic cleaning process of the second ultrasonic cleaning station in step S4 uses pure water for cleaning, the water temperature is room temperature, and the cleaning time is 1-5 minutes.

[0025] As an improvement, the drying process in step S5 bakes the product surface at a temperature of 120-150° C. for 10-40 minutes.

[0026] As an improvement, the cooling process in step S5 cools the product by direct cooling with a fan, and the cooling time is 5-20 minutes.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] (1) The present invention adopts a novel phosphating solution, the main components of which include phosphoric acid, manganese phosphate, zinc dihydrogen phosphate, cobalt nitrate, alkylphenol polyoxyethylene ether, sodium fluoride, tartaric acid, and benzotriazole. The alkylphenol polyoxyethylene ether is a surfactant, tartaric acid is a complexing agent, and sodium fluoride is a promoter. The configuration concentration is 8Vol%-20Vol%, and the pH value is controlled at 1.5-2.5. The temperature of the phosphating solution phosphating product is room temperature, and the phosphating time is 5-15 minutes. The alkylphenol polyoxyethylene ether in the phosphating solution has a certain degreasing ability, and the acid phosphate has a certain pickling and oxide layer removal ability. At the same time, tartaric acid as a complexing agent has the effect of refining the phosphating film, improving the corrosion resistance and preventing patch printing. For this reason, the conventional degreasing and pickling pre-treatment processes are removed in the production, the process flow is reduced, the sewage discharge is reduced, and the loss of the pre-treatment to the size of the magnetic steel is reduced, thereby reducing the production cost;

[0029] (2) The present invention no longer uses the conventional drum and mesh bag mode for phosphating, but uses a conveyor belt to transport the products to the corresponding workstations for the corresponding processing steps, which can ensure stable transportation of the products, thereby reducing the chipping caused by collision between the products;

[0030] (3) The present invention can effectively remove dirt and phosphating residual liquid on the product surface through the arrangement of the first and second spraying stations and the first and second ultrasonic cleaning stations, thereby ensuring the cleanliness of the product surface. The duration of spraying and ultrasonic cleaning, water temperature and other parameters are also precisely controlled to achieve the best cleaning effect.

[0031] (4) The drying process of the present invention adopts appropriate temperature and duration to ensure that the moisture on the surface of the product is completely removed while avoiding overheating damage to the product. The cooling process uses direct cooling by a fan to quickly reduce the product temperature, preparing for subsequent packaging and storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0033] Figure 1 A schematic diagram of a simplified process for phosphating a small-angle NdFeB magnetic steel;

[0034] Figure 2 This is a schematic diagram of the surface electron microscope of the product of Example 1;

[0035] Figure 3 This is the appearance diagram of the phosphating of NdFeB magnetic steel in Example 1;

[0036] Figure 4 This is the appearance diagram of the phosphating NdFeB magnetic steel of Example 2;

[0037] Figure 5 This is the appearance diagram of the phosphating NdFeB magnet of Example 3. DETAILED DESCRIPTION

[0038] Embodiment 1

[0039] like Figures 1 to 3 As shown, a method for phosphating a small-angle NdFeB magnetic steel comprises the following steps:

[0040] S1.1: Evenly spread the NdFeB magnets on the conveyor belt;

[0041] S1.2: The transmission wheel drives the conveyor belt to move the NdFeB magnet to the first spraying station for spraying. The spraying process of the first spraying station uses tap water or pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0042] S1.3: After the spraying is completed, the transmission wheel drives the conveyor belt to move the NdFeB magnet to the first ultrasonic cleaning station for ultrasonic cleaning. The ultrasonic cleaning process of the first ultrasonic cleaning station uses tap water or pure water for cleaning. The water temperature is 50°C and the cleaning time is 6 minutes.

[0043] S2.1: preparing a phosphating solution, wherein the solute and solution of the phosphating solution are respectively prepared in a solvent and a solute, and the solvent is deionized water or distilled water;

[0044] S2.2: Add 1 / 2 level of solvent into the preparation tank;

[0045] S2.3: Pour the prepared 100 g / L phosphoric acid into the preparation tank as shown in Table 1 and stir to completely dissolve it;

[0046] S2.4: Add the prepared 25 g / L manganese phosphate, 30 g / L zinc dihydrogen phosphate, 3 g / L cobalt nitrate, and 1 g / L sodium fluoride into the preparation tank in sequence, and stir to completely dissolve;

[0047] S2.5: Add the prepared 9 g / L alkylphenol polyoxyethylene ether, 0.4 g / L tartaric acid, and 3 g / L benzotriazole into the preparation tank in sequence, and stir to completely dissolve them;

[0048] S2.6: Pour the remaining solvent into the preparation tank, and then stir evenly to obtain the phosphating solution;

[0049] S2.7: The conveyor belt transports the NdFeB magnet to the phosphating station and performs the phosphating process through the phosphating solution, wherein the concentration of the phosphating solution is 10 Vol%, the pH value of the phosphating solution is 2.5, and the phosphating solution phosphates the NdFeB magnet at room temperature for 10 minutes;

[0050] S3.1: The conveyor belt transports the NdFeB magnet to the second spraying station for spraying. The spraying process of the second spraying station uses pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0051] S3.2: After spraying, high-pressure wind shearing is performed to blow away part of the phosphating residual liquid remaining on the surface of the NdFeB magnet;

[0052] S4.1: The conveyor belt transports the NdFeB magnet to the second ultrasonic cleaning station for ultrasonic cleaning to clean the other part of the phosphating residual liquid on the surface of the NdFeB magnet. The ultrasonic cleaning process of the second ultrasonic cleaning station uses pure water for cleaning, the water temperature is room temperature, and the cleaning time is 3 minutes;

[0053] S4.2: After cleaning, high-pressure air cutting is performed to blow away the residual moisture on the surface of the NdFeB magnet;

[0054] S5.1: The conveyor belt transports the NdFeB magnet to the drying station for the drying process. The drying process uses a temperature of 130°C to bake the surface of the NdFeB magnet for 30 minutes;

[0055] S5.2: After drying, the conveyor belt transports the NdFeB magnet to the cooling station for cooling process. The cooling process cools the NdFeB magnet by direct cooling with a fan, and the cooling time is 15 minutes.

[0056] S5.3: The cooled NdFeB magnets are transported to the bagging station via a conveyor belt.

[0057] As shown in Table 2, the NdFeB magnet obtained by the method for phosphating the small-angle NdFeB magnet of the present invention is subjected to a salt water immersion test. The test is performed in accordance with the provisions of the national standard GB / T6807. The salt water immersion test can reach a qualified level after 8 hours. The phosphating appearance of the small-angle NdFeB magnet in Example 1 is dust-free and rust-free, and its color is yellow-brown.

[0058] Embodiment 2

[0059] like Figure 1 , Figure 4 As shown, a method for phosphating a small-angle NdFeB magnetic steel comprises the following steps:

[0060] S1.1: Evenly spread the NdFeB magnets on the conveyor belt;

[0061] S1.2: The transmission wheel drives the conveyor belt to move the NdFeB magnet to the first spraying station for spraying. The spraying process of the first spraying station uses tap water or pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0062] S1.3: After the spraying is completed, the transmission wheel drives the conveyor belt to move the NdFeB magnet to the first ultrasonic cleaning station for ultrasonic cleaning. The ultrasonic cleaning process of the first ultrasonic cleaning station uses tap water or pure water for cleaning. The water temperature is 50°C and the cleaning time is 6 minutes.

[0063] S2.1: preparing a phosphating solution, wherein the solute and solution of the phosphating solution are respectively prepared in a solvent and a solute, and the solvent is deionized water or distilled water;

[0064] S2.2: Add 1 / 2 level of solvent into the preparation tank;

[0065] S2.3: Pour the prepared 150 g / L phosphoric acid into the preparation tank as shown in Table 1 and stir to completely dissolve it;

[0066] S2.4: Add the prepared 25 g / L manganese phosphate, 40 g / L zinc dihydrogen phosphate, 6 g / L cobalt nitrate, and 1 g / L sodium fluoride into the preparation tank in sequence, and stir to completely dissolve them;

[0067] S2.5: Add the prepared 6 g / L alkylphenol polyoxyethylene ether, 0.5 g / L tartaric acid, and 3 g / L benzotriazole into the preparation tank in sequence, and stir to completely dissolve them;

[0068] S2.6: Pour the remaining solvent into the preparation tank, and then stir evenly to obtain the phosphating solution;

[0069] S2.7: The conveyor belt transports the NdFeB magnet to the phosphating station and performs the phosphating process through the phosphating solution, wherein the concentration of the phosphating solution is 10 Vol%, the pH value of the phosphating solution is 2, and the phosphating solution phosphates the NdFeB magnet at room temperature for 8 minutes;

[0070] S3.1: The conveyor belt transports the NdFeB magnet to the second spraying station for spraying. The spraying process of the second spraying station uses pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0071] S3.2: After spraying, high-pressure wind shearing is performed to blow away part of the phosphating residual liquid remaining on the surface of the NdFeB magnet;

[0072] S4.1: The conveyor belt transports the NdFeB magnet to the second ultrasonic cleaning station for ultrasonic cleaning to clean the other part of the phosphating residual liquid on the surface of the NdFeB magnet. The ultrasonic cleaning process of the second ultrasonic cleaning station uses pure water for cleaning, the water temperature is room temperature, and the cleaning time is 3 minutes;

[0073] S4.2: After cleaning, high-pressure air cutting is performed to blow away the residual moisture on the surface of the NdFeB magnet;

[0074] S5.1: The conveyor belt transports the NdFeB magnet to the drying station for the drying process. The drying process uses a temperature of 130°C to bake the surface of the NdFeB magnet for 30 minutes;

[0075] S5.2: After drying, the conveyor belt transports the NdFeB magnet to the cooling station for cooling process. The cooling process cools the NdFeB magnet by direct cooling with a fan, and the cooling time is 15 minutes.

[0076] S5.3: The cooled NdFeB magnets are transported to the bagging station via a conveyor belt.

[0077] As shown in Table 2, the NdFeB magnets obtained by the method for phosphating small-angle NdFeB magnets of the present invention were subjected to a salt water immersion test. The test was performed in accordance with the provisions of the national standard GB / T6807. The salt water immersion test can reach a qualified level after 16 hours. The phosphating small-angle NdFeB magnets in Example 2 have no dust or rust spots on their appearance, and their color is bluish-gray.

[0078] Embodiment 3

[0079] like Figure 1 , Figure 5 As shown, a method for phosphating a small-angle NdFeB magnetic steel comprises the following steps:

[0080] S1.1: Evenly spread the NdFeB magnets on the conveyor belt;

[0081] S1.2: The transmission wheel drives the conveyor belt to move the NdFeB magnet to the first spraying station for spraying. The spraying process of the first spraying station uses tap water or pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0082] S1.3: After the spraying is completed, the transmission wheel drives the conveyor belt to move the NdFeB magnet to the first ultrasonic cleaning station for ultrasonic cleaning. The ultrasonic cleaning process of the first ultrasonic cleaning station uses tap water or pure water for cleaning. The water temperature is 50°C and the cleaning time is 6 minutes.

[0083] S2.1: preparing a phosphating solution, wherein the solute and solution of the phosphating solution are respectively prepared in a solvent and a solute, and the solvent is deionized water or distilled water;

[0084] S2.2: Add 1 / 2 level of solvent into the preparation tank;

[0085] S2.3: Pour the prepared 200 g / L phosphoric acid into the preparation tank as shown in Table 1 and stir to completely dissolve it;

[0086] S2.4: Add the prepared 30 g / L manganese phosphate, 50 g / L zinc dihydrogen phosphate, 10 g / L cobalt nitrate, and 1.5 g / L sodium fluoride into the preparation tank in sequence, and stir to completely dissolve them;

[0087] S2.5: Add the prepared 9 g / L alkylphenol polyoxyethylene ether, 0.8 g / L tartaric acid, and 4 g / L benzotriazole into the preparation tank in sequence, and stir to completely dissolve them;

[0088] S2.6: Pour the remaining solvent into the preparation tank, and then stir evenly to obtain the phosphating solution;

[0089] S2.7: The conveyor belt transports the NdFeB magnet to the phosphating station and performs the phosphating process through the phosphating solution, wherein the concentration of the phosphating solution is 10 Vol%, the pH value of the phosphating solution is 1.5, and the phosphating solution phosphates the NdFeB magnet at room temperature for 8 minutes;

[0090] S3.1: The conveyor belt transports the NdFeB magnet to the second spraying station for spraying. The spraying process of the second spraying station uses pure water for spraying. The water temperature is room temperature and the spraying time is 30 seconds.

[0091] S3.2: After spraying, high-pressure wind shearing is performed to blow away part of the phosphating residual liquid remaining on the surface of the NdFeB magnet;

[0092] S4.1: The conveyor belt transports the NdFeB magnet to the second ultrasonic cleaning station for ultrasonic cleaning to clean the other part of the phosphating residual liquid on the surface of the NdFeB magnet. The ultrasonic cleaning process of the second ultrasonic cleaning station uses pure water for cleaning, the water temperature is room temperature, and the cleaning time is 3 minutes;

[0093] S4.2: After cleaning, high-pressure air cutting is performed to blow away the residual moisture on the surface of the NdFeB magnet;

[0094] S5.1: The conveyor belt transports the NdFeB magnet to the drying station for the drying process. The drying process uses a temperature of 130°C to bake the surface of the NdFeB magnet for 30 minutes;

[0095] S5.2: After drying, the conveyor belt transports the NdFeB magnet to the cooling station for cooling process. The cooling process cools the NdFeB magnet by direct cooling with a fan, and the cooling time is 15 minutes.

[0096] S5.3: The cooled NdFeB magnets are transported to the bagging station via a conveyor belt.

[0097] As shown in Table 2, the NdFeB magnets obtained by the method for phosphating small-angle NdFeB magnets of the present invention were subjected to a salt water immersion test, and the test was carried out in accordance with the provisions of the national standard GB / T6807. The salt water immersion test can reach a qualified level for 24 hours. The phosphating small-angle NdFeB magnets in Example 2 have no dust or rust spots on their appearance, and their color is gray-black.

[0098] Table 1 Composition of each component in the phosphating solution in Examples 1 to 3

[0099]

[0100] Table 2 Test results of NdFeB magnets in Examples 1 to 3

[0101] project Phosphate appearance Salt water soak Embodiment 1 No dust, no rust spots; brown in color 8h Embodiment 2 No dust, no rust spots; blue-gray color 16h Embodiment 3 No dust, no rust spots; gray-black color 24h

[0102] It can be seen from the test results in the above table that: the higher the concentration of each component in the new phosphating solution, the longer the brine immersion time, the acidity of Example 1 is relatively weak, suitable for treating NdFeB magnets with relatively shallow oxide layers, and the oil removal ability is relatively strong, and the appearance of the product after treatment is brown-yellow; the components of Example 2 are prepared in a medium proportion, the pickling, oil removal and rust prevention abilities are relatively average, and the product appearance is bluish-gray; Example 3 is prepared in a high concentration, has a strong acidity, a relatively thick phosphating film layer, has higher corrosion resistance, and the product appearance is gray-black.

[0103] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for phosphating small-angle NdFeB magnets, characterized in that: The following steps are involved: S1: The product is evenly dispersed and placed on the conveyor belt, and moves with the conveyor belt to the first spraying station for spraying process, and then enters the first ultrasonic cleaning station for ultrasonic cleaning process; S2: The conveyor belt transports the product to the phosphating station and performs the phosphating process through the phosphating solution, wherein the phosphating solution includes a solvent and a solute, wherein the solvent is deionized water or distilled water, and the solute includes 100-200 g / L phosphoric acid, 20-30 g / L manganese phosphate, 30-50 g / L zinc dihydrogen phosphate, 3-10 g / L cobalt nitrate, 3-9 g / L alkylphenol polyoxyethylene ether, 0.5-1.5 g / L sodium fluoride, 0.2-1.5 g / L tartaric acid, and 2-4 g / L benzotriazole; S3: The conveyor belt transports the product to the second spraying station for spraying. After spraying, high-pressure air shearing is performed to blow away part of the phosphating residual liquid remaining on the surface of the product; S4: The conveyor belt transports the product to the second ultrasonic cleaning station for ultrasonic cleaning to clean the other part of the phosphating residual liquid on the surface of the product. After the cleaning is completed, high-pressure air shearing is performed to blow away the residual moisture on the surface of the product; S5: The conveyor belt transports the product to the drying station for drying process, and then enters the cooling station for cooling process, and the cooled product is transported to the material receiving and bagging station through the conveyor belt.

2. The method for phosphating a small-angle NdFeB magnetic steel according to claim 1, characterized in that: The spraying process of the first spraying station in step S1 uses tap water or pure water for spraying, the water temperature is room temperature, and the spraying time is 10-50 seconds.

3. The method for phosphating a small-angle NdFeB magnetic steel according to claim 1, characterized in that: The ultrasonic cleaning process of the first ultrasonic cleaning station in step S1 is performed using tap water or pure water, the water temperature is 40-60° C., and the cleaning time is 2-8 minutes.

4. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: When the phosphating process is performed by using a phosphating solution in step S2, the phosphating solution needs to be prepared first, which specifically includes the following steps: S2.1: preparing the solvent and the solute respectively according to the solute and solution ratio of the phosphating solution; S2.2: Add 1 / 2 level of solvent into the preparation tank; S2.3: Pour the prepared phosphoric acid into the preparation tank and stir to dissolve it completely; S2.4: Add the prepared manganese phosphate, zinc dihydrogen phosphate, cobalt nitrate and sodium fluoride into the preparation tank in sequence, and stir to completely dissolve them; S2.5: Add the prepared alkylphenol polyoxyethylene ether, tartaric acid and benzotriazole into the preparation tank in sequence, and stir to completely dissolve them; S2.6: Pour the remaining solvent into the preparation tank, and then stir evenly to obtain the phosphating solution.

5. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: In the phosphating solution in step S2, alkylphenol polyoxyethylene ether is a surfactant, tartaric acid is a complexing agent, and sodium fluoride is a accelerator.

6. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: The concentration of the phosphating solution in the phosphating process in step S2 is 8 Vol%-20 Vol%, the pH value of the phosphating solution is 1.5-2.5, and the phosphating solution phosphates the product at room temperature for 5-15 minutes.

7. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: The spraying process of the second spraying station in step S3 uses pure water for spraying, the water temperature is room temperature, and the spraying time is 10-50 seconds.

8. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: The ultrasonic cleaning process of the second ultrasonic cleaning station in step S4 uses pure water for cleaning, the water temperature is room temperature, and the cleaning time is 1-5 minutes.

9. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: The drying process in step S5 bakes the product surface at a temperature of 120-150° C. for 10-40 minutes.

10. The method for phosphating small-angle NdFeB magnetic steel according to claim 1, characterized in that: The cooling process in step S5 cools the product by direct cooling with a fan, and the cooling time is 5-20 minutes.

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