Vacuum crushing production process and equipment for rapidly quenching neodymium-iron-boron magnetic powder

Abstract

The invention discloses a vacuum crushing production process and equipment for rapidly-quenched Nd-Fe-B magnetic powder, and relates to the technical field of vacuum crushing production, and the vacuum crushing production process comprises the following operation steps: S1, after roughly crushing a rapidly-quenched Nd-Fe-B thin strip, continuously feeding the thin strip into a crushing area; s2, performing multi-stage shearing and crushing on the material to reduce the particle size to 0.5-2 mm; s3, the crushed particles are subjected to online screening, fine powder smaller than or equal to 150 micrometers is separated and collected immediately, and coarse particles are automatically sent back to the crushing area to be circularly crushed till all the particles pass through a 100-mesh screen; and S4, no external gas enters the whole process, and the powder oxygen increment is smaller than or equal to 200 ppm. According to the vacuum crushing production process and equipment for the rapid quenching neodymium-iron-boron magnetic powder, the whole crushing, screening and returning process is completed in the same vacuum cavity, no external air invades, and the oxygen increment of the powder is stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vacuum crushing production, in particular to a vacuum crushing production process and equipment for rapidly quenched neodymium-iron-boron magnetic powder. BACKGROUND

[0002] Neodymium-iron-boron permanent magnet material is widely used in the fields of motor, sensor, medical device, etc. due to its high magnetic energy product and high coercive force. The isotropic bonded magnet takes rapidly quenched Nd-Fe-B magnetic powder as raw material, has the advantages of low forming pressure, high dimensional accuracy, and one-time injection molding with embedded parts. The rapidly quenched strip is brittle after rapid quenching of the melt, and needs to be crushed and sieved to obtain magnetic powder with appropriate particle size; however, the crushing process is accompanied by severe plastic deformation and local temperature rise, which easily causes oxidation and carbon increase, resulting in a decrease in Hcj of the magnetic powder and an increase in oxygen content.

[0003] Currently, the two-stage process of "atmospheric coarse crushing + inert gas protection screening" is generally used in industry, which has defects such as high oxygen increase (>1000 ppm), wide particle size distribution, and large loss of fine powder flying. Although there have been attempts to extract negative pressure from the crushing cavity, problems such as short service life of dynamic seal, dust pollution of vacuum system, and inability of coarse particles to return online have not been solved, making it difficult to produce continuously.

[0004] Therefore, it is necessary to provide a vacuum crushing production process and equipment for rapidly quenched neodymium-iron-boron magnetic powder to solve the above problems. SUMMARY

[0005] The present application aims to provide a vacuum crushing production process and equipment for rapidly quenched neodymium-iron-boron magnetic powder to solve the problems of high oxygen increase, wide particle size distribution, and large loss of fine powder flying. Although there have been attempts to extract negative pressure from the crushing cavity, problems such as short service life of dynamic seal, dust pollution of vacuum system, and inability of coarse particles to return online have not been solved, making it difficult to produce continuously.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a vacuum crushing production process for rapidly quenched neodymium-iron-boron magnetic powder, comprising the following operation steps:

[0007] S1, continuously feeding the rapidly quenched Nd-Fe-B thin strip after coarse crushing into the crushing zone;

[0008] S2, implementing multi-stage shearing crushing on the material to reduce the particle size to 0.5-2 mm;

[0009] S3, performing online screening on the crushed particles, the fine powder ≤150 μm is immediately separated and collected, and the coarse particles are automatically returned to the crushing zone for cyclic crushing until all pass through the 100 mesh screen;

[0010] S4, no external gas enters the whole process, and the oxygen increase of the powder is ≤200 ppm;

[0011] S5, after the crushing, argon is filled in the cavity to normal pressure and the magnetic powder D is discharged 50 = 60-90 μm.

[0012] Preferably, the multi-stage shearing crushing adopts a double-roller opposite rotation mode, the roller surface linear velocity is 5-15 m·s -1 , the gap between the two rollers is 0.3-1.0 mm, and the single-batch processing capacity is 20-100 kg·h -1 .

[0013] Preferably, the on-line screening and the coarse particle returning are completed in the same vacuum cavity, and the returning process is completed through intermittent air flow disturbance or mechanical vibration.

[0014] Preferably, before being sent into the crushing area, the coarse crushing material is vacuum degassed at 60-80 ℃ and under the condition of an absolute pressure of ≤500 Pa for 30-60 min.

[0015] Preferably, before being discharged, the powder is subjected to inert gas circulating air cooling in the vacuum cavity, so that the powder temperature is ≤40 ℃ and then the vacuum is broken.

[0016] The application further discloses a vacuum crushing production equipment for the rapidly-quenched neodymium-iron-boron magnetic powder.

[0017] The inner wall of the cylinder is fixedly connected with a partition block, one side of the partition block is vertical, and the other side is inclined, a plurality of partition blocks are evenly distributed around the axis of the cylinder, and a lifting chamber is formed between adjacent two partition blocks.

[0018] The inside of the cylinder is provided with a crushing hopper, and the inside of the crushing hopper is provided with a crushing roller.

[0019] Preferably, a plurality of circular holes are formed in the side wall of the cylinder, the plurality of circular holes are distributed in one-to-one correspondence with the plurality of lifting chambers, a sliding rod is slidably arranged in the circular hole, one end of the sliding rod in the cylinder is fixedly connected with an elastic telescopic rod, the other end of the elastic telescopic rod away from the sliding rod is fixedly connected to the inner wall of the cylinder, a scraper is arranged in the lifting chamber, the scraper is fixedly connected to the sliding rod, a plurality of convex blocks are fixedly connected to the inner wall of the vacuum box, the plurality of convex blocks are evenly distributed around the axis of the cylinder, and the sliding rod is in abutting connection with the convex blocks.

[0020] Preferably, a third circular groove is arranged on the side of the vacuum box away from the first circular groove, a fixed block is fixedly connected in the third circular groove, a second circular groove is arranged on the cylinder for the fixed block to pass through, the second circular groove has the same diameter as the third circular groove, the fixed block is fixedly connected to the outer wall of the crushing hopper, and a feeding seat is fixedly connected to the top end of the fixed block.

[0021] Preferably, two crushing rollers are arranged, the crushing rollers are arranged in cooperation with each other, a rotating shaft is fixedly connected to the crushing roller, and the rotating shaft is rotatably arranged on the fixed block and extends to the outside of the fixed block.

[0022] Preferably, a fixed frame is fixedly connected to the outer wall of the vacuum box, a motor is fixedly connected to the fixed frame, and the cylinder is fixedly connected to the driving shaft of the motor.

[0023] Technical effects and advantages of the present application:

[0024] 1. In the vacuum crushing production process of the rapidly quenched neodymium-iron-boron magnetic powder, the entire crushing, screening and returning process is completed in the same vacuum cavity, without external air intrusion, and the oxygen increment of the powder is stable.

[0025] 2. The crushing, screening and returning are integrated, the utilization rate of the equipment is high, the cooling, argon filling and discharging can be completed in the vacuum cavity, without repeated transfer, and the production rhythm is shortened.

[0026] 3. By arranging the partition block, the lifting chamber and the crushing hopper, the functions of screening, material turning, anti-accumulation and conveying are realized, and the use efficiency of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder is improved.

[0027] 4. By arranging the sliding rod and the scraper, the material in the lifting chamber is pushed and scraped, the screening is accelerated, and the speed of the large particle blocks sliding into the crushing hopper is accelerated, and the use efficiency of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a process flow chart of the vacuum crushing production process of the rapidly quenched neodymium-iron-boron magnetic powder.

[0029] Figure 2 It is a perspective structural schematic view of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder.

[0030] Figure 3 It is another perspective structural schematic view of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder.

[0031] Figure 4 It is a sectional structural schematic view of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder.

[0032] Figure 5 This is a schematic diagram of the vacuum box and cylindrical structure of the present invention.

[0033] Figure 6 For the present invention Figure 5 Enlarged schematic diagram of the structure at point A in the middle.

[0034] Figure 7 This is a schematic diagram of the cylindrical and second circular groove structures of the present invention.

[0035] Figure 8 This is a schematic diagram of the vacuum box and bump structure of the present invention.

[0036] Figure 9 This is a schematic diagram of the crushing bucket and block structure of the present invention.

[0037] In the diagram: 1. Vacuum box; 2. First circular groove; 3. Cylinder; 4. Second circular groove; 5. Filter hole; 6. Partition block; 7. Lifting chamber; 8. Crushing bucket; 9. Fixed block; 10. Rotating shaft; 11. Crushing roller; 12. Feed seat; 13. Feed channel; 14. Fixing frame; 15. Motor; 16. Circular hole; 17. Slide rod; 18. Scraper; 19. Protrusion; 20. Elastic telescopic rod; 21. Third circular groove. Detailed Implementation

[0038] This invention provides, for example Figures 1-9 The vacuum crushing process for rapidly quenched NdFeB magnetic powder shown includes the following steps:

[0039] S1. The rapidly quenched Nd-Fe-B thin strip is coarsely crushed and then continuously fed into the crushing zone;

[0040] S2. Perform multi-stage shearing and crushing on the material to reduce the particle size to 0.5-2mm;

[0041] S3. The crushed particles are screened online. Fine powder ≤150μm is immediately separated and collected, while coarse particles are automatically returned to the crushing zone for recycling until all of them pass through a 100-mesh screen.

[0042] S4. No external gas enters the entire process, and the oxygen increment of the powder is ≤200ppm;

[0043] S5. After crushing, the cavity is filled with argon to atmospheric pressure and the material is discharged, resulting in magnetic powder D. 50 =60–90μm.

[0044] Furthermore, the upper steps are completed sequentially within the same vacuum chamber with an absolute pressure ≤1000Pa.

[0045] Multi-stage shear crushing employs a double-roller counter-rotating mechanism with a roller surface linear velocity of 5–15 m / s. -1The two-roller gap is 0.3-1.0 mm, and the single-batch processing capacity is 20-100 kg / h -1 .

[0046] The on-line screening and coarse particle returning are completed in the same vacuum chamber, and the returning process is completed through intermittent air flow disturbance or mechanical vibration.

[0047] Before being fed into the crushing zone, the coarse broken material is vacuum degassed at 60-80 DEG C and under the condition of absolute pressure of less than or equal to 500 Pa for 30-60 min.

[0048] Before being discharged, the powder is subjected to inert gas circulating air cooling in the vacuum chamber, so that the powder temperature is less than or equal to 40 DEG C, and then the vacuum is broken.

[0049] The application further discloses a vacuum crushing production equipment for the rapidly-quenched neodymium-iron-boron magnetic powder, which is applied to the vacuum crushing production process for the rapidly-quenched neodymium-iron-boron magnetic powder and further comprises a vacuum box 1, the bottom end of the vacuum box 1 is connected with a vacuum powder receiving bin, and the vacuum box 1 is used for collecting the material after crushing; a first circular groove 2 is formed in the side wall of the vacuum box 1, a cylinder 3 is rotatably arranged in the first circular groove 2, in actual use, a ball bearing or the like is arranged between the first circular groove 2 and the cylinder 3, the smoothness of rotation of the cylinder 3 is ensured, and a vacuum system (including a vacuum pump and the like) is connected with the vacuum box 1, so that the crushing production is carried out in a vacuum environment.

[0050] A fixing frame 14 is fixedly connected to the outer wall of the vacuum box 1, a motor 15 is fixedly connected to the fixing frame 14, the cylinder 3 is fixedly connected to the driving shaft of the motor 15, and the motor 15 is connected with the power supply of a factory, so that the cylinder 3 is driven to rotate by the motor 15.

[0051] In consideration of the fact that part of large-particle material blocks will still remain after single crushing, a plurality of filter holes 5 are formed in the annular wall of the cylinder 3, and the inner diameter of the filter holes 5 is relatively small.

[0052] A crushing hopper 8 is arranged in the cylinder 3, a crushing roller 11 is arranged in the crushing hopper 8, a third circular groove 21 is formed in the side of the vacuum box 1 away from the first circular groove 2, a fixed block 9 is fixedly connected to the inside of the third circular groove 21, a second circular groove 4 is formed in the cylinder 3 and used for allowing the fixed block 9 to pass through, the second circular groove 4 and the third circular groove 21 have the same diameter, and the fixed block 9 is fixedly connected to the outer wall of the crushing hopper 8.

[0053] The two crushing rollers 11 are coaxially arranged on the shaft 10, the shaft 10 is rotationally arranged on the fixed block 9, and the shaft 10 extends to the outside of the fixed block 9. In actual use, the part of the shaft 10 extending to the outside of the fixed block 9 is provided with a gear, the two gears are meshed and connected, and the fixed block 9 is fixedly provided with a motor, and one of the shafts 10 is fixedly connected to the driving shaft of the motor (not shown in the figure); when running, the motor drives the shaft 10 fixedly connected to the driving shaft to rotate, so that the corresponding gear rotates, and because the two gears are meshed and connected, the two crushing rollers 11 rotate to crush the material.

[0054] The top end of the fixed block 9 is fixedly connected with a feeding seat 12, the feeding seat 12 is provided with a feeding channel 13 for feeding, and the feeding channel 13 is matched with the crushing hopper 8. Specifically, a screw feeder or the like is provided to cooperate with the feeding channel 13 to convey the material from the feeding channel 13 to the inside of the crushing hopper 8, and the two crushing rollers 11 rotate to crush the material.

[0055] The inner wall of the cylinder 3 is fixedly connected with a partition block 6, one side of the partition block 6 is vertical, and the other side is inclined.

[0056] The partition block 6 is provided with a plurality of partition blocks 6, the plurality of partition blocks 6 are uniformly distributed around the axis of the cylinder 3, and the adjacent two partition blocks 6 form a lifting chamber 7.

[0057] In actual use, the motor 15 drives the cylinder 3 to rotate, so that one of the lifting chambers 7 is located below the crushing hopper 8, the material is conveyed from the feeding channel 13 to the inside of the crushing hopper 8, and the two crushing rollers 11 rotate to crush the material, the powdery material slides downward through the filter hole 5, and the remaining part of the large particle block falls into the lifting chamber 7, realizing the function of screening.

[0058] At the same time, the cylinder 3 can be controlled to switch between forward rotation and reverse rotation, the material is turned over, the speed of the powdery material passing through the filter hole 5 is accelerated, and the function of turning over the material is realized.

[0059] If there are too many large particle blocks remaining in the lifting chamber 7, the cylinder 3 is controlled to continue to rotate, and the inclined side of the partition block 6 is located at the front end of the rotation direction of the cylinder 3, so that the next lifting chamber 7 is located below the crushing hopper 8, and the plurality of lifting chambers 7 are switched for use, so that the single lifting chamber 7 does not accumulate too much to affect the speed of the material passing through the filter hole 5 and sliding downward.

[0060] If it is needed to pour the residual large particle lumps in the lifting chamber 7 into the inside of the crushing hopper 8 again, the control cylinder 3 continues to rotate, and the inclined side of the partition block 6 is at the front end of the rotating direction of the cylinder 3, and when the lifting chamber 7 rotates to the upper side of the crushing hopper 8, the residual large particle lumps slide into the inside of the crushing hopper 8, realizing the conveying function and crushing again; in the process of rotating the lifting chamber 7 to the upper side of the crushing hopper 8, the large particle lumps are accumulated close to the inclined side of the partition block 6, and only when it is at the upper side of the crushing hopper 8, it will slide down.

[0061] By setting the partition block 6, the lifting chamber 7 and the crushing hopper 8 and other structures, the functions of screening, material stirring, anti-accumulation and conveying are realized, and the use efficiency of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder is improved.

[0062] In order to further speed up the screening efficiency, a plurality of circular holes 16 are formed on the side wall of the cylinder 3, the plurality of circular holes 16 are distributed one by one corresponding to the plurality of lifting chambers 7, a sliding rod 17 is slidably arranged in the inside of the circular hole 16, one end of the sliding rod 17 located in the inside of the cylinder 3 is fixedly connected with an elastic telescopic rod 20, and the other end of the elastic telescopic rod 20 away from the sliding rod 17 is fixedly connected to the inner wall of the cylinder 3; a scraper 18 is arranged in the lifting chamber 7, the scraper 18 is fixedly connected to the sliding rod 17, a plurality of protrusions 19 are fixedly connected to the inner wall of the vacuum box 1, the plurality of protrusions 19 are uniformly distributed around the axis of the cylinder 3, and the sliding rod 17 is in abutting cooperation with the protrusions 19.

[0063] In use, the motor 15 drives the cylinder 3 to rotate, when the sliding rod 17 contacts the protrusion 19, the sliding rod 17 will move towards the elastic telescopic rod 20 and extrude the elastic telescopic rod 20 to contract; when the sliding rod 17 is staggered with the protrusion 19, the reset elastic force of the elastic telescopic rod 20 makes the sliding rod 17 reset, and the cylinder 3 rotates forward and reversely for several times, so that the sliding rod 17 reciprocally moves, the scraper 18 pushes and scrapes the material in the lifting chamber 7 to speed up the screening; at the same time, when the residual large particle lumps slide into the inside of the crushing hopper 8, the scraping of the scraper 18 can speed up the sliding speed.

[0064] By setting the sliding rod 17, the scraper 18 and other structures, the material in the lifting chamber 7 is pushed and scraped to speed up the screening, and the speed of the large particle lumps sliding into the inside of the crushing hopper 8 can be speeded up, and the use efficiency of the vacuum crushing production equipment of the rapidly quenched neodymium-iron-boron magnetic powder is further improved.

Claims

1. A vacuum crushing process for rapidly quenched NdFeB magnetic powder, characterized in that: The following steps are included: S1. The rapidly quenched Nd-Fe-B thin strip is coarsely crushed and then continuously fed into the crushing zone; S2. Perform multi-stage shearing and crushing on the material to reduce the particle size to 0.5-2mm; S3. The crushed particles are screened online. Fine powder ≤150μm is immediately separated and collected, while coarse particles are automatically returned to the crushing zone for recycling until all of them pass through a 100-mesh screen. S4. No external gas enters the entire process, and the oxygen increment of the powder is ≤200ppm; S5. After crushing, the cavity is filled with argon to atmospheric pressure and the material is discharged, resulting in magnetic powder D. 50 =60–90μm.

2. The vacuum crushing production process for rapidly quenched NdFeB magnetic powder according to claim 1, characterized in that: Multi-stage shear crushing employs a double-roller counter-rotating mechanism with a roller surface linear velocity of 5–15 m / s. -1 The gap between the two rollers is 0.3–1.0 mm, and the single batch processing capacity is 20–100 kg·h. -1 .

3. The vacuum crushing production process for rapidly quenched NdFeB magnetic powder according to claim 1, characterized in that: Online screening and coarse particle return are completed in the same vacuum chamber, with the return process achieved through intermittent airflow disturbance or mechanical vibration.

4. The vacuum crushing production process for rapidly quenched NdFeB magnetic powder according to claim 1, characterized in that: Before being fed into the crushing zone, the coarsely crushed material is first degassed under vacuum at 60-80℃ and absolute pressure ≤500Pa for 30-60 minutes.

5. The vacuum crushing production process for rapidly quenched NdFeB magnetic powder according to claim 1, characterized in that: Before discharge, the powder is cooled by circulating inert gas in the vacuum chamber until the powder temperature is ≤40℃ before the vacuum is broken.

6. A vacuum crushing production equipment for rapidly quenched NdFeB magnetic powder, characterized in that: The vacuum crushing production process for rapidly quenched NdFeB magnetic powder as described in any one of claims 1 to 5 further includes a vacuum chamber (1), a first circular groove (2) is provided on the side wall of the vacuum chamber (1), a cylinder (3) is rotatably arranged inside the first circular groove (2), and a plurality of filter holes (5) are provided on the annular wall of the cylinder (3). A partition (6) is fixedly connected to the inner wall of the cylinder (3). One side of the partition (6) is vertical and the other side is inclined. Multiple partitions (6) are provided and are evenly distributed around the axis of the cylinder (3). A lifting chamber (7) is formed between two adjacent partitions (6). The cylinder (3) is provided with a crushing bucket (8) inside, and the crushing bucket (8) is provided with a crushing roller (11) inside.

7. The vacuum crushing production equipment for rapidly quenched NdFeB magnetic powder according to claim 6, characterized in that: The cylinder (3) has a circular hole (16) on its side wall. There are multiple circular holes (16), and each circular hole (16) corresponds to a multiple lifting chamber (7). A sliding rod (17) is slidably installed inside the circular hole (16). One end of the sliding rod (17) inside the cylinder (3) is fixedly connected to an elastic telescopic rod (20). The end of the elastic telescopic rod (20) away from the sliding rod (17) is fixedly connected to the inner wall of the cylinder (3). A scraper (18) is installed in the lifting chamber (7). The scraper (18) is fixedly connected to the sliding rod (17). A protrusion (19) is fixedly connected to the inner wall of the vacuum box (1). There are multiple protrusions (19), and the multiple protrusions (19) are evenly distributed around the axis of the cylinder (3). The sliding rod (17) and the protrusion (19) abut against each other.

8. The vacuum crushing production equipment for rapidly quenched NdFeB magnetic powder according to claim 7, characterized in that: A third circular groove (21) is provided on the side of the vacuum box (1) away from the first circular groove (2). A fixed block (9) is fixedly connected inside the third circular groove (21). A second circular groove (4) is provided on the cylinder (3) for the fixed block (9) to pass through. The diameter of the second circular groove (4) is the same as that of the third circular groove (21). The fixed block (9) is fixedly connected to the outer wall of the crushing bucket (8). A feed seat (12) is fixedly connected to the top of the fixed block (9). A feed channel (13) for feeding is provided on the feed seat (12), and the feed channel (13) cooperates with the crushing bucket (8).

9. The vacuum crushing production equipment for rapidly quenched NdFeB magnetic powder according to claim 6, characterized in that: Two crushing rollers (11) are provided, and the two crushing rollers (11) cooperate with each other. A rotating shaft (10) is fixedly connected to the crushing roller (11). The rotating shaft (10) is rotatably mounted on the fixed block (9) and extends to the outside of the fixed block (9).

10. The vacuum crushing production equipment for rapidly quenched NdFeB magnetic powder according to claim 6, characterized in that: A fixed frame (14) is fixedly connected to the outer wall of the vacuum chamber (1), and a motor (15) is fixedly connected to the fixed frame (14). The cylinder (3) is fixedly connected to the drive shaft of the motor (15).

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