Radiation ring magnetic field compression molding method

Abstract

The invention discloses a radiation ring magnetic field compression molding method which comprises the following steps: S1, moving a core rod to a position where the core rod is 10-20mm lower than a mold, and spraying a mold release agent to a mold cavity by a mold release agent spraying device; s2, the feeding device fills the quantitative neodymium iron boron powder into the die cavity, then the lower driving part gradually drives the lower die punch to move downwards by the stroke of L1 mm, and after the lower die punch moves downwards by the stroke of L1 mm every time, the feeding device gradually fills the quantitative neodymium iron boron powder into the die cavity; s3, the upper punch moves downwards into the die cavity to pre-press the neodymium iron boron powder; s4, an upper electromagnet assembly fixed to the upper guide plate and a lower electromagnet assembly fixed to the lower guide plate are powered on for T1 min; then the upper punch moves downwards, the core pulling electric cylinder drives the core rod to move downwards synchronously along with the upper punch, and the lower driving piece drives the lower punch to move upwards until pressing is completed; s5, the upward moving distance of the upper punch is L2 mm, and the set duration is kept; and S6, compression molding is conducted, and therefore it is guaranteed that the density of the neodymium iron boron powder is

Description

Technical Field

[0001] The invention relates to the technical field of NdFeB processing, and in particular to a radiation ring magnetic field pressing and forming method. Background Art

[0002] The magnetic field forming press mainly includes a sealed frame, in which a powder weighing device, a feeding device and a forming device are installed. The NdFeB powder first enters the powder weighing device through a barrel, and the powder weighing device weighs a certain amount of NdFeB powder and then loads it into the feeding device. Finally, the feeding device pushes it to the forming device, and the NdFeB powder is loaded into a forming mold, and then the NdFeB powder is pressed and formed.

[0003] The powder weighing device is an important component of the NdFeB powder magnetic field forming press. The feeding process of the NdFeB forming press includes: the NdFeB powder first enters the weighing device through the barrel, the weighing device weighs a certain amount of NdFeB powder and then loads it into the powder adding device, and finally the feeding device pushes the powder adding device to the forming mold and loads the NdFeB powder into the forming mold.

[0004] The existing magnetic field forming press uses a powder adding device to fill the NdFeB powder into the mold cavity at one time. However, due to the small gap of the annular cavity of the mold cavity, the NdFeB powder will adhere to the peripheral wall of the annular cavity and affect its uniform sinking in the mold cavity, which will cause the density distribution of the NdFeB powder in the mold cavity to be uneven, thereby affecting the yield of the NdFeB magnet. In addition, the NdFeB powder has poor fluidity in the narrow annular cavity and bridging will occur, resulting in excessive density in some areas of the mold cavity and low density in some areas. Therefore, the density distribution of the NdFeB powder in the mold cavity is uneven, affecting the yield of the NdFeB magnet. Summary of the invention

[0005] The purpose of the present invention is to provide a radiation ring magnetic field pressing molding method, which can ensure the uniform density of the NdFeB powder in the mold cavity by discontinuously moving the lower die punch downward and coordinating the batch feeding of NdFeB powder, thereby ensuring the finished product rate of NdFeB magnets.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A method for forming a radiation ring magnetic field, comprising the following steps: S1: Spraying release agent: The core-pulling electric cylinder drives the core rod to move to a position where the upper end surface of the core rod is 10mm-20mm lower than the upper end surface of the mold, and the release agent spraying device sprays the release agent into the mold cavity; S2: Filling NdFeB powder: First, the core-pulling electric cylinder drives the core rod to move up to a position where the upper end surface of the core rod is not lower than the upper end surface of the mold. Then, the lower driving member drives the lower die punch to move to a position where the upper end surface of the lower die punch is lower than the upper end surface of the mold by L1mm. The feeding device fills a certain amount of NdFeB powder into the mold cavity. Then, the lower driving member gradually drives the lower die punch to move down by L1mm. After each downward movement of the lower die punch by L1mm, the feeding device gradually fills a certain amount of NdFeB powder into the mold cavity until the filling of NdFeB powder is completed. S3: Upper punch pre-pressing: The core rod and the lower punch remain stationary, and the upper driving member drives the upper punch to move downward into the die cavity to pre-press the NdFeB powder; S4: Compression molding: First, the upper punch, the lower punch and the core rod are kept stationary, and the upper electromagnet assembly fixed to the upper guide plate and the lower electromagnet assembly fixed to the lower guide plate are energized for T1min; then, the upper driving member drives the upper punch to move downward, the core-pulling electric cylinder drives the core rod to move downward synchronously with the upper punch, and the lower driving member drives the lower punch to move upward, thereby pressing the NdFeB powder in the die cavity for T2min until the pressing is completed; S5: Stress release: The lower punch and the core rod remain stationary, and the upper driving member drives the upper punch to move up a distance of L2mm and maintain the set time to release the stress of the formed NdFeB magnetic ring; S6: Demolding: The upper driving member drives the upper punch to move upward, the lower driving member drives the lower punch to move upward, and the core-pulling electric cylinder drives the core rod to move upward, thereby demolding the formed NdFeB magnetic ring.

[0007] Further, in step S2, the upper end surface of the lower die punch is lower than the upper end surface of the die by L1 mm, wherein 10≤L1≤20.

[0008] Further, in step S3, during pre-pressing, the lower end surface of the upper punch extends into the die cavity by 4 mm to 6 mm.

[0009] Further, in step S5, the upper driving member drives the upper punch to move upward a distance L2mm, wherein 0.5≤L2≤2.

[0010] Further, in step S5, the upper driving member drives the upper punch to move up by L2 mm and lasts for 1-2 seconds.

[0011] Further, in step S6, after the lower punch moves up until its upper end surface is flush with the upper end surface of the mold, the core-pulling electric cylinder drives the core rod to move down into the mold cavity.

[0012] Furthermore, in step S2, the core-pulling electric cylinder drives the core rod to move up to a position where the upper end surface of the core rod is flush with the upper end surface of the mold, so that the feeding device can reciprocate along the mold, and each time the feeding device moves, it fills a certain amount of NdFeB powder into the mold cavity.

[0013] In summary, the present invention has the following beneficial effects: 1. The present invention can ensure uniform density of NdFeB powder in the die cavity by discontinuous downward movement of the lower die punch and batch feeding of NdFeB powder, thereby ensuring the yield of NdFeB magnets; 2. Before pressing the NdFeB powder, the present invention first sets the duration of powering on the upper electromagnet assembly and the lower electromagnet assembly, that is, after the upper electromagnet assembly and the lower electromagnet assembly are powered on, the upper pole and the lower pole are delayed for a certain period of time for pressing, thereby ensuring more uniform magnetization and better magnetization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention.

[0015] Figure 2 It is a schematic diagram of the internal structure of the mold cavity of the present invention.

[0016] Figure 3 The present invention Figure 2 Enlarged view of point A.

[0017] In the figure: 10, frame; 20, upper driving member; 21, upper guide plate; 22, upper electromagnet assembly; 221, upper electromagnetic coil; 222, upper pole; 223, upper pole head; 23, upper die punch; 231, blind groove; 30, lower driving member; 31, lower guide plate; 311, avoidance channel; 32, lower electromagnet assembly; 321, lower electromagnetic coil; 322, lower pole; 323, lower pole head; 33, lower die punch; 40, core-pulling cylinder; 41, core rod; 50, magnetic plate; 51, mold; 60, feeding device. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings.

[0019] like Figure 1-Figure 3 As shown, a radiation ring magnetic field pressing molding method includes a frame 10, a mold 51 arranged in the middle of the frame 10, an upper guide plate 21 arranged at the upper end of the mold 51, an upper punch 23 and an upper electromagnet assembly 22 fixed to the lower end of the upper guide plate 21, an upper driving member 20 for driving the upper guide plate 21 to rise and fall, a lower guide plate 31 arranged at the lower end of the mold 51, a lower punch 33 and a lower electromagnet assembly 32 fixed to the upper end of the lower guide plate 31, a lower driving member 30 for driving the lower guide plate 31 to rise and fall, a core pulling cylinder 40 arranged at the bottom of the frame 10, a core rod 41 connected to the core pulling cylinder 40, a feeding device 60 that can be slidably arranged along the frame 10, and a demoulding agent spraying device arranged at the front end of the feeding device 60, a mold cavity is provided in the mold 51, The radiation ring magnetic field pressing molding method comprises the following steps: S1: Spraying the release agent: The core-pulling electric cylinder 40 drives the core rod 41 to move to a position where the upper end surface of the core rod 41 is 10 mm-20 mm lower than the upper end surface of the mold 51, and the release agent spraying device sprays the release agent into the mold cavity; S2: Filling NdFeB powder: First, the core-pulling electric cylinder 40 drives the core rod 41 to move up to a position where the upper end surface of the core rod 41 is not lower than the upper end surface of the mold 51, then the lower driving member 30 drives the lower die punch 33 to move to a position where the upper end surface of the lower die punch 33 is lower than the upper end surface of the mold 51 by L1mm, and the feeding device 60 fills a certain amount of NdFeB powder into the mold cavity. Then, the lower driving member 30 gradually drives the lower die punch 33 to move down by a stroke of L1mm. After each downward movement of the lower die punch 33 by L1mm, the feeding device 60 gradually fills a certain amount of NdFeB powder into the mold cavity until the filling of the NdFeB powder is completed; S3: Pre-pressing the upper punch 23: The core rod 41 and the lower punch 33 remain stationary, and the upper driving member 20 drives the upper punch 23 to move downward into the die cavity to pre-press the NdFeB powder; S4: Compression molding: First, the upper punch 23, the lower punch 33 and the core rod 41 remain stationary, and the upper electromagnet assembly 22 fixed to the upper guide plate 21 and the lower electromagnet assembly 32 fixed to the lower guide plate 31 are energized for T1min; then, the upper driving member 20 drives the upper punch 23 to move downward, the core-pulling electric cylinder 40 drives the core rod 41 to move downward synchronously with the upper punch 23, and the lower driving member 30 drives the lower punch 33 to move upward, thereby pressing the NdFeB powder in the mold cavity for T2min until the pressing is completed; S5: stress release: the lower punch 33 and the core rod 41 remain stationary, and the upper driving member 20 drives the upper punch 23 to move up a distance of L2 mm and maintain the set time to release the stress of the formed NdFeB magnetic ring; S6: Demolding: The upper driving member 20 drives the upper punch 23 to move upward, the lower driving member 30 drives the lower punch 33 to move upward, and the core-pulling electric cylinder 40 drives the core rod 41 to move upward, thereby demolding the molded NdFeB magnetic ring.

[0020] Before step S1 or during step S1 , a set amount of NdFeB powder is weighed by a powder weighing device, and after weighing, the powder weighing device transfers the NdFeB powder to a powder box of the feeding device 60 .

[0021] The mold 51 is a female mold, which is fixedly installed in the middle of the molding press through a magnetic conductive plate 50. The magnetic conductive plate 50 has the following functions: 1. It forms a magnetic circuit during magnetization, reduces magnetic leakage, and improves the magnetic field strength of the mold cavity; 2. It is used to fix the female mold and improve the pressing accuracy.

[0022] In step S1 , the core-pulling electric cylinder 40 drives the core rod 41 to sink to a position 10 mm to 20 mm below the upper end surface of the mold 51 , so that the release agent falls more evenly.

[0023] In some embodiments, in step S2 , the upper end surface of the lower punch 33 is lower than the upper end surface of the die 51 by L1 mm, where 10≤L1≤20.

[0024] In some embodiments, in step S2, the feeding device 60 reciprocates along the mold 51 to discharge the NdFeB powder. Specifically, the feeding device 60 moves once and discharges a certain amount of NdFeB powder, that is, the lower driving member 30 drives the lower punch 33 to move down by L1mm, and the feeding device 60 moves once and pours a certain amount of NdFeB powder. The lower punch 33 moves downward intermittently and the NdFeB powder is discharged in batches. The NdFeB powder in the powder box of the feeding device 60 after being weighed by the powder weighing device will be discharged in batches during the above process, which can ensure that the density of the NdFeB powder in the mold cavity is uniform, thereby ensuring the yield of the NdFeB magnet.

[0025] In some embodiments, in step S3, when the upper punch 23 is pre-pressed, the lower end surface of the upper punch 23 extends into the die cavity by 4 mm-6 mm, preferably, the lower end surface of the upper punch 23 extends into the die cavity by 5 mm.

[0026] In some embodiments, in step S4 , while the upper driving member 20 drives the upper punch 23 to pre-press, the core rod 41 and the lower punch 33 remain stationary.

[0027] The pre-pressing step before pressing can make the density of the NdFeB powder in the mold cavity more uniform, thereby improving the yield rate of the NdFeB magnetic ring.

[0028] In some embodiments, in step S5, the upper driving member 20 drives the upper punch 23 to move up a distance of L2mm, where 0.5≤L2≤2. In step S5, the upper driving member 20 drives the upper punch 23 to move up L2mm and lasts for 1-2 seconds. Through the above arrangement, the stress of the pressed NdFeB magnetic ring can be effectively released.

[0029] In some embodiments, in step S6, the upper driving member 20, the lower driving member 30 and the core-pulling electric cylinder 40 synchronously drive the corresponding upper punch 23, the lower punch 33 and the core rod 41 to move upward. In step S6, after the lower punch 33 moves up until its upper end surface is flush with the upper end surface of the mold 51, the core-pulling electric cylinder 40 drives the core rod 41 to move down into the mold cavity.

[0030] In some embodiments, in step S2, the core-pulling electric cylinder 40 drives the core rod 41 to move upward to a position where the upper end surface of the core rod 41 is flush with the upper end surface of the mold 51, so that the feeding device 60 can reciprocate along the mold 51, and each time the feeding device 60 moves, it fills a certain amount of neodymium iron boron powder into the mold cavity.

[0031] In some embodiments, the upper electromagnet assembly 22 includes an upper pole 222 fixed to the upper guide plate 21, an upper pole head 223 fixed to the lower end of the upper pole 222, and an upper electromagnetic coil 221 fixed to the outer periphery of the upper pole 222, the upper punch 23 is fixed to the lower end of the upper pole head 223, the upper drive member 20 is fixedly connected to the upper guide plate 21, the lower electromagnet assembly 32 includes a lower pole 322 fixed to the lower guide plate 31, a lower pole head 323 fixed to the upper end of the lower pole 322, and a lower electromagnetic coil 321 fixed to the outer periphery of the lower pole 322, the lower punch 33 is fixed to the upper end of the lower pole head 323, the lower drive member 30 is fixedly connected to the lower guide plate 31, and the lower guide plate 31, the lower pole 322, the lower pole head 323 and the lower punch 33 are provided with an avoidance channel for the core rod 41 to pass through.

[0032] In some embodiments, the lower end surface of the upper pole head 223 is provided with a blind groove 231 adapted to the core rod 41, and the depth of the blind groove 231 is 5-6 mm. Specifically, the depth of the blind groove 231 is slightly greater than 5 mm. Through the setting of the blind groove 231, it can not only play a positioning role, but also play a role in guiding magnetic lines of force.

[0033] In some embodiments, the upper driving member 20 and the lower driving member 30 are electric cylinders, the lower guide plate 31 is provided with a guide hole that slides with the guide post, and the lower electromagnet assembly 32 is fixedly installed on the upper end of the lower guide plate 31. Specifically, the upper driving member 20 is fixedly installed on the top of the frame 10, the output end of the upper driving member 20 is fixedly connected to the upper guide plate 21, the frame 10 is provided with guide posts around, the upper guide plate 21 is provided with a guide hole that slides with the guide post, and the upper electromagnet assembly 22 is fixedly installed on the lower end of the upper guide plate 21. The lower driving member 30 is a lower left electric cylinder and a lower right electric cylinder fixedly arranged at the bottom of the frame 10. By setting two groups of electric cylinders, under the premise of avoiding the core-pulling electric cylinder 40, the two groups of electric cylinders can improve the stability of driving the lower guide plate 31 to move.

[0034] The core-pulling electric cylinder 40 is fixedly arranged at the middle of the lower end of the frame 10 , and the output end of the core-pulling electric cylinder 40 is fixedly connected to the core rod 41 .

[0035] Before pressing the NdFeB powder, the present invention first sets the duration of powering on the upper electromagnet assembly 22 and the lower electromagnet assembly 32, that is, after the upper electromagnet assembly 22 and the lower electromagnet assembly 32 are powered on, the upper pole 222 and the lower pole 322 are delayed for a certain period of time for pressing, thereby ensuring more uniform magnetization and better magnetization effect.

[0036] When the upper electromagnetic coil 221 and the lower electromagnetic coil 321 are energized, the upper electromagnetic coil 221 and the lower electromagnetic coil 321 are set to repel each other. For example, when the upper end of the upper electromagnetic coil 221 is the N pole and the lower end is the S pole, the upper end of the lower electromagnetic coil 321 is the S pole and the lower end is the N pole; similarly, when the upper end of the upper electromagnetic coil 221 is the S pole and the lower end is the N pole, the upper end of the lower electromagnetic coil 321 is the N pole and the lower end is the S pole, and the magnetic lines of force of the upper electromagnetic coil 221 and the lower electromagnetic coil 321 form a repelling radiation field in the middle of the mold 51.

[0037] The above description is only a preferred embodiment of the present invention, so all equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A method for pressing and forming a radiation ring magnetic field, characterized in that: The following steps are involved: S1: Spraying a demoulding agent: The core-pulling electric cylinder (40) drives the core rod (41) to move to a position where the upper end surface of the core rod (41) is 10 mm to 20 mm lower than the upper end surface of the mold (51), and the demoulding agent spraying device sprays the demoulding agent into the mold cavity; S2: Filling NdFeB powder: First, the core-pulling electric cylinder (40) drives the core rod (41) to move up to a position where the upper end surface of the core rod (41) is not lower than the upper end surface of the mold (51), then the lower driving member (30) drives the lower die punch (33) to move to a position where the upper end surface of the lower die punch (33) is lower than the upper end surface of the mold (51) by L1 mm, and the feeding device (60) fills a certain amount of NdFeB powder into the mold cavity, then, the lower driving member (30) gradually drives the lower die punch (33) to move down by a stroke of L1 mm, and after each downward movement of the lower die punch (33) by a stroke of L1 mm, the feeding device (60) gradually fills a certain amount of NdFeB powder into the mold cavity until the filling of the NdFeB powder is completed; S3: pre-pressing the upper die punch (23): the core rod (41) and the lower die punch (33) remain stationary, and the upper driving member (20) drives the upper die punch (23) to move downward into the die cavity to pre-press the NdFeB powder; S4: Compression molding: First, the upper die punch (23), the lower die punch (33) and the core rod (41) remain stationary, and the upper electromagnet assembly (22) fixed to the upper guide plate (21) and the lower electromagnet assembly (32) fixed to the lower guide plate (31) are energized for T1min; then, the upper driving member (20) drives the upper die punch (23) to move downward, the core pulling electric cylinder (40) drives the core rod (41) to move downward synchronously with the upper die punch (23), and the lower driving member (30) drives the lower die punch (33) to move upward, thereby pressing the NdFeB powder in the die cavity for T2min until the pressing is completed; S5: stress release: the lower punch (33) and the core rod (41) remain stationary, and the upper driving member (20) drives the upper punch (23) to move up a distance of L2 mm and maintain the movement for a set time to release the stress of the molded NdFeB magnetic ring; S6: Demolding: The upper driving member (20) drives the upper die punch (23) to move upward, the lower driving member (30) drives the lower die punch (33) to move upward, and the core-pulling electric cylinder (40) drives the core rod (41) to move upward, thereby demolding the molded NdFeB magnetic ring.

2. The method for forming a radiation ring magnetic field according to claim 1, characterized in that: In step S2, the upper end surface of the lower punch (33) is lower than the upper end surface of the mold (51) by L1 mm, where 10≤L1≤20.

3. The method for forming a radial ring magnetic field according to claim 2, characterized in that: In step S3, when the upper die punch (23) is pre-pressed, the lower end surface of the upper die punch (23) extends into the die cavity by 4mm-6mm.

4. The method for forming a radiation ring magnetic field according to claim 1, characterized in that: In step S5, the upper driving member (20) drives the upper punch (23) to move upward by a distance L2mm, wherein 0.5≤L2≤2.

5. The method for forming a radiation ring magnetic field according to claim 4, characterized in that: In step S5, the upper driving member (20) drives the upper punch (23) to move up by L2 mm and lasts for 1-2 seconds.

6. The method for forming a radiation ring magnetic field according to claim 1, characterized in that: In step S6, when the lower punch (33) moves up until its upper end surface is flush with the upper end surface of the mold (51), the core-pulling electric cylinder (40) drives the core rod (41) to move down into the mold cavity.

7. The method for forming a radiation ring magnetic field according to claim 1, characterized in that: In step S2, the core-pulling electric cylinder (40) drives the core rod (41) to move upward to a position where the upper end surface of the core rod (41) is flush with the upper end surface of the mold (51), so that the feeding device (60) can reciprocate along the mold (51), and each time the feeding device (60) moves, a fixed amount of neodymium iron boron powder is filled into the mold cavity.

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