Injection molding magnetizing mold for sheet magnet

Abstract

The injection magnetizing mold comprises a body, the body comprises a mold cavity used for forming the sheet magnet, the mold cavity is formed by splicing an upper mold body arranged at the upper end of the mold cavity and a lower mold body arranged at the lower end of the mold cavity, and the lower mold body comprises a lower magnetic base and an ejector block; the ejection block is arranged under the mold cavity and used for ejecting out the formed sheet magnet, the ejection block is arranged in one magnetic pole of the lower magnetic base, the upper mold comprises an upper magnetic base and a shaping block, the shaping block is used for forming the upper end face of the sheet magnet, an annular magnetic field is formed between the upper magnetic base and the lower magnetic base, and the annular magnetic field is located between the upper magnetic base and the lower magnetic base. And an orientation magnetic field for performing magnetic orientation on the sheet magnet is formed between the top block and the shaping block through the annular magnetic field. According to the injection molding magnetizing mold for the sheet magnet, the distribution position of a magnetic field of oriented magnetic steel is changed, and the orientation efficiency of magnetic orientation is improved.

Description

Technical Field

[0001] The invention belongs to the field of magnet molding, and particularly relates to an injection molding magnetization mold for a thin-sheet magnet. Background Art

[0002] Magnets have been widely used in our lives. On some magnetic blackboards, thin sheet magnets are often used to adsorb paper or teaching aids on the blackboard. Because these thin sheet magnets have low requirements for magnetic attraction, magnetic powder is often mixed with other materials to form magnetic mud, and then produced by magnetic mud injection molding, thereby reducing the magnetic material content of the product and achieving the purpose of increasing the output of thin sheet magnets.

[0003] During the injection molding process of thin-film magnets, the magnetic mud during injection molding needs to be magnetically oriented to increase the maximum magnetic force upper limit of the thin-film magnets. In the conventional production process, magnetic steels are respectively provided on the two end faces used to mold the thin-film magnets to form a unidirectional magnetic field, which is used to realize the magnetic orientation work during the injection molding of the thin-film magnets. However, in order to ensure the consistency of the magnetic orientation direction, the area of ​​the magnetic steel used needs to be much larger than the area of ​​the thin-film magnets. If the area of ​​the magnetic steel is similar to the area of ​​the thin-film magnets, the magnetic orientation direction formed by the thin-film magnets will be diffuse and have poor parallelism. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the present invention proposes an injection molding magnetization mold for a thin-film magnet, which changes the magnetic field distribution position of an oriented magnetic steel and improves the orientation efficiency of the magnetic orientation.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: an injection molding magnetization mold for a thin film magnet, comprising a main body, the main body comprising a mold cavity for molding the thin film magnet, the mold cavity is formed by assembling an upper mold arranged at the upper end of the mold cavity and a lower mold arranged at the lower end of the mold cavity, the lower mold comprises a lower magnetic seat and a top block, the top block is arranged directly below the mold cavity and is used to eject the molded thin film magnet, the top block is arranged in a magnetic pole of the lower magnetic seat, the upper mold comprises an upper magnetic seat and a shaping block, the shaping block is used to shape the upper end surface of the thin film magnet, an annular magnetic field is formed between the upper magnetic seat and the lower magnetic seat, and an orientation magnetic field for magnetically orienting the thin film magnet is formed between the top block and the shaping block through the annular magnetic field.

[0006] Compared with the prior art, the advantages of the present invention are: the two end faces of the thin film magnet are formed by using a top block and a shaping block, and the magnetic orientation of the thin film magnet is completed by the annular magnetic field formed between the upper magnetic seat and the lower magnetic seat. Compared with the conventional magnetic orientation structure, the annular magnetic field has a stronger magnetic field convergence, is not easy to diffuse, and is not easy to cause the attenuation of the magnetic field strength, thereby improving the efficiency of the magnetic orientation. If you want to use the conventional upper and lower distributed magnetic steels to achieve the same magnetic field strength attenuation, the relative overlapping area of ​​the two magnetic steels needs to be much larger than the end face area of ​​the thin film magnet.

[0007] As an improvement, the main body includes an injection port and an injection channel, the injection port is vertically arranged, and the injection channel is horizontally arranged between the injection port and the mold cavity. Through the improvement, the mold cavity is laterally injected to avoid affecting the orientation magnetic field strength. Compared with the conventional injection molding process, the injection port is not easy to interfere with the annular magnetic field and is easier to approach the mold cavity, so that the mold has a smaller structure while meeting the purposes of injection molding and magnetic orientation.

[0008] As an improvement, there are a plurality of mold cavities, and there is one injection port, and the plurality of mold cavities are arranged in a uniform array along the circumference of the injection port. Through the improvement, simultaneous injection molding of a plurality of thin-film magnets can be achieved.

[0009] As an improvement, the molding block is annular and sleeved on the outer wall of the injection port, the upper magnetic seat is annular and sleeved on the molding block, and the magnetic field of the upper magnetic seat is distributed radially. Through the improvement, the molding blocks used for upper end surface molding of multiple mold cavities are integrated, the molding structure is more unified, and the injection structure is more stable. The magnetic field distribution of the upper magnetic seat can more easily ensure the controllability of the magnetic field between the upper magnetic seat and the lower magnetic seat, so as to ensure the stability of the formation of the annular magnetic field, thereby ensuring the stability of the magnetic orientation of the thin film magnet.

[0010] As an improvement, the lower magnetic seat is provided with a plurality of ejector blocks corresponding to the mold cavity one by one, and the lower magnetic seat is also provided with an ejector column corresponding to the injection port, and the ejector column is used to eject the injection material at the connection between the injection port and the injection runner. Through the improvement, after the molding of the thin film magnet is completed, the thin film magnet needs to be ejected from the mold cavity by the ejector block, but because the structure of the thin film magnet is thin and the strength is weak, the thickness of the structure formed at the injection runner is thicker and the strength is higher than that of the thin film magnet. If the injection material at the injection runner is demolded by ejecting the thin film magnet, it is very easy to cause the thin film magnet to break, and the injection material in the injection runner will also be retained in the injection runner. Therefore, it is necessary to design an ejector column specifically for ejecting the injection material in the injection runner.

[0011] As an improvement, during injection molding, the top height of the ejector pin is lower than the height of the injection molding runner. Through the improvement, during the injection molding process, there is air. Normally, the air will be discharged along the distance between the ejector pin and the lower magnetic base and the gap between the ejector block and the lower magnetic base, and the injection molding material will use its own tension to close these gaps after the air is discharged. However, due to the design of one injection port and multiple mold cavities, the air flow in the mold becomes unstable during injection molding, that is, it cannot be guaranteed that the injection pressure is uniform when injecting into multiple mold cavities. By designing that the top height of the ejector pin is lower than the height of the injection molding runner, a buffer cavity can be formed at the connection between the injection port and the injection molding runner. The injection molding material is buffered by the buffer cavity and then injected into the injection molding runner, thereby better ensuring the uniformity of injection molding of each injection molding runner. At the same time, part of the air can be confined in the buffer cavity and discharged from the gap between the ejector pin and the lower magnetic base.

[0012] As an improvement, the magnetic field of the lower magnetic seat is also distributed radially and the direction of the magnetic field is opposite to that of the upper magnetic seat. Through the improvement, an annular magnetic field is formed between the lower magnetic seat and the upper magnetic seat.

[0013] As an improvement, an annular magnet is provided between the upper magnetic seat and the lower magnetic seat, and the magnet is provided on the outer ring of the lower magnetic seat. The two poles of the magnet are respectively provided at the upper and lower ends of the magnet, and the upper end of the mold cavity is not higher than the upper end of the magnet, and the lower end of the mold cavity is not lower than the lower end of the magnet. Through the improvement, the formation of an annular magnetic field is realized, and the axiality of the magnetic field at the mold cavity is guaranteed when the magnetic field is formed.

[0014] As an improvement, the main body also includes a magnetic beam layer, which is made of non-magnetic hard material. The magnetic beam layer is arranged on the outer ring of the upper mold, the lower mold and the magnetic steel and wraps the upper mold, the lower mold and the magnetic steel. Through the improvement, the magnetic field strength of the magnetic steel can be converged between the upper mold and the lower mold, increasing the magnetic field distribution density between the upper mold and the lower mold, thereby enhancing the orientation magnetic field.

[0015] As an improvement, the inner circle of the upper magnetic seat is offset against the lower magnetic seat. Through the improvement, not only can the upper magnetic seat and the shaping block be kept at the same level, the magnetic field formed can be more stably converged, but also the magnetic inductance break between the upper magnetic seat and the lower magnetic seat can be avoided, resulting in the problem of magnetic field strength attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall cross-sectional structure of the present invention.

[0017] Figure 2 It is an enlarged schematic diagram of the mold cavity connection structure of the present invention.

[0018] Figure 3 It is a schematic diagram of the cross-sectional structure of the beam magnetic layer of the present invention.

[0019] Figure 4 It is a schematic diagram of the annular magnetic field distribution structure of the present invention.

[0020] Figure 5 It is a schematic diagram of the structure of the injection molding material of the present invention after being shaped in a mold.

[0021] Figure 6 It is a schematic diagram of the conventional thin-film magnet injection molding structure of the present invention.

[0022] As shown in the figure: 1. mold cavity, 2. upper mold, 2.1. upper magnetic seat, 2.2. shaping block, 3. lower mold, 3.1. lower magnetic seat, 3.2. top block, 4. injection port, 5. injection runner, 6. top column, 7. buffer cavity, 8. magnetic steel, 9. magnetic beam layer. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0024] like Figure 1-4 As shown, an injection molding magnetization mold for a thin-film magnet comprises a body, the body comprises a mold cavity 1 for molding the thin-film magnet, the mold cavity 1 is formed by assembling an upper mold 2 arranged at the upper end of the mold cavity 1 and a lower mold 3 arranged at the lower end of the mold cavity 1, the lower mold 3 comprises a lower magnetic seat 3.1 and a top block 3.2, the top block 3.2 is arranged directly below the mold cavity 1 and is used to eject the molded thin-film magnet, the top block 3.2 is arranged in a magnetic pole of the lower magnetic seat 3.1, the upper mold 2 comprises an upper magnetic seat 2.1 and a shaping block 2.2, the shaping block 2.2 is used to shape the upper end surface of the thin-film magnet, an annular magnetic field is formed between the upper magnetic seat 2.1 and the lower magnetic seat 3.1, and an orientation magnetic field for magnetically orienting the thin-film magnet is formed between the top block 3.2 and the shaping block 2.2 through the annular magnetic field.

[0025] The materials of the upper magnetic base 2.1, the lower magnetic base 3.1, the shaping block 2.2 and the top block 3.2 are all magnetic conductive materials of H13 mold steel. The magnetic field at the top block 3.2 is constrained by the action of the lower magnetic base 3.1 and can only form a unidirectional magnetic field.

[0026] like Figure 1 , Figure 2 , Figure 5 As shown, the main body includes an injection port 4 and an injection channel 5, the injection port 4 is vertically arranged, and the injection channel 5 is horizontally arranged between the injection port 4 and the mold cavity 1. There are four mold cavities 1 in total, and the injection port 4 is provided with one, and the four mold cavities 1 are arranged in a uniform array along the circumference of the injection port 4.

[0027] like Figure 2 , Figure 4As shown, the shaping block 2.2 is annular and sleeved on the outer wall of the injection port 4, the upper magnetic base 2.1 is annular and sleeved on the shaping block 2.2, the magnetic field of the upper magnetic base 2.1 is distributed radially, and the magnetic field of the lower magnetic base 3.1 is also distributed radially and the direction of the magnetic field is opposite to that of the upper magnetic base 2.1.

[0028] The lower magnetic base 3.1 is provided with a plurality of top blocks 3.2 corresponding to the mold cavity 1 one by one. The lower magnetic base 3.1 is also provided with a top column 6 corresponding to the injection port 4. The top column 6 is used to eject the injection material at the connection between the injection port 4 and the injection channel 5. The top height of the top column 6 is lower than the height of the injection channel 5. A buffer cavity 7 is formed at the connection between the injection port 4 and the injection channel 5. The injection material is buffered by the buffer cavity 7 and then injected into the injection channel 5, so as to better ensure the uniformity of injection of each injection channel 5. At the same time, part of the air can be confined in the buffer cavity 7 and discharged from the gap between the top column 6 and the lower magnetic base 3.1.

[0029] An annular magnet 8 is provided between the upper magnetic seat 2.1 and the lower magnetic seat 3.1. The magnet 8 is a neodymium iron boron high temperature resistant permanent magnet. The magnet 8 is provided on the outer ring of the lower magnetic seat 3.1. The two poles of the magnet 8 are respectively provided on the upper and lower ends of the magnet 8. The upper end of the mold cavity 1 is not higher than the upper end of the magnet 8, and the lower end of the mold cavity 1 is not lower than the lower end of the magnet 8. The body also includes a beam magnetic layer 9, and the beam magnetic layer 9 is made of non-magnetic hard material. The beam magnetic layer 9 is provided on the outer ring of the upper mold 2, the lower mold 3 and the magnet 8 and wraps the upper mold 2, the lower mold 3 and the magnet 8. The inner ring of the upper magnetic seat 2.1 is against the lower magnetic seat 3.1.

[0030] The magnetic beam layer 9 can be made of SUS316 stainless steel material, which ensures the overall strength of the mold without having magnetic conductivity.

[0031] During the injection molding and magnetic orientation process of the thin-film magnet, a closed magnetic field is formed by using the annular magnetic steel 8, and a stable unidirectional magnetic field is formed at the mold cavity 1, thereby ensuring the unidirectionality of the magnetic orientation of the mold cavity 1, and then the upper magnetic seat 2.1, the shaping block 2.2 and the lower magnetic seat 3.1 are used to guide and converge the magnetic field, reduce the outward diffusion of the magnetic field intensity, and ensure the high intensity of the formed annular magnetic field. In the distribution of magnetic field intensity, if there is no stable magnetic conductive material for guidance, the magnetic field intensity will decay in stages with the distance from the magnetic steel 8, because the mold cavity 1 forms a magnetic conductive ring through the upper magnetic seat 2.1, the lower magnetic seat 3.1, and the shaping block 2.2, and the magnetic field attenuation of the beam magnetic layer 9 forms a magnetic conductive ring that attracts the magnetic field that should have been formed in the beam magnetic layer, making the magnetic field intensity of the magnetic conductive ring stronger, and the orientation magnetic field of the thin-film magnet is stronger. However, after the thin-film magnet is formed, it is necessary to perform a demolding operation. At this time, the shaping block 2.2 will be separated from the lower magnetic base 3.1. If the shaping block 2.2 and the upper magnetic base 2.1 are designed as an integral whole, the upper magnetic base 2.1 will also be separated from the lower magnetic base 3.1. When the mold is closed again next time, they will be offset against each other. At the same time, the upper end surface of the magnetic steel 8 is also exposed due to the separation of the upper magnetic base 2.1. Repeating this process may lead to repeated collisions between the upper magnetic base 2.1 and the magnetic steel 8, causing damage to the magnetic steel 8. If impurities are adsorbed on the magnetic steel 8, it is also easy to cause a gap to form between the upper magnetic base 2.1 and the lower magnetic base 3.1 when the mold is closed, resulting in a significant decrease in the magnetic field capacity of the attraction beam magnetic layer 9.

[0032] like Figure 1 As shown, the upper magnetic base 2.1 is ring-shaped. During the fixing process of the upper magnetic base 2.1, the magnetic beam layer adopts an upper and lower split design, and the upper magnetic base 2.1 is fixedly installed by using the fixed connection between the upper and lower parts of the magnetic beam layer 9, thereby ensuring the integrity of the upper magnetic base 2.1 structure and making the magnetic conductive ring structure more stable.

[0033] like Figure 6 As shown, using the conventional magnetic orientation process and the orientation process of this mold with the same magnetic field strength, the conventional magnetic orientation can only form a magnetic induction intensity of 0.5T, while the magnetic orientation formed by this mold can form a magnetic induction intensity of 0.8T. One of the main reasons is that in the process of ensuring the magnetic orientation, the conventional process expands the area of ​​the magnetic field to ensure the unidirectionality of the magnetic field strength, and does not converge the magnetic field, resulting in a waste of magnetic field strength. At the same time, compared with the conventional process, the structure of this mold is more compact, occupies less space, and the injection runner 5 will also extend between the upper magnetic seat 2.1 and the lower magnetic seat 3.1, affecting the stability of the magnetic field between the upper magnetic seat 2.1 and the lower magnetic seat 3.1.

[0034] The above description is only for the best embodiment of the present invention, but it should not be interpreted as a limitation of the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. All changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

Claims

1. An injection molding magnetization mold for a thin sheet magnet, comprising a body, characterized in that: The main body comprises a mold cavity (1) for molding a thin-film magnet. The mold cavity (1) is formed by assembling an upper mold (2) arranged at the upper end of the mold cavity (1) and a lower mold (3) arranged at the lower end of the mold cavity (1). The lower mold (3) comprises a lower magnetic seat (3.1) and a top block (3.2). The top block (3.2) is arranged directly below the mold cavity (1) and is used to eject the molded thin-film magnet. The top block (3.2) is arranged in a magnetic pole of the lower magnetic seat (3.1). The upper mold (2) comprises an upper magnetic seat (2.1) and a shaping block (2.2). The shaping block (2.2) is used to shape the upper end surface of the thin-film magnet. An annular magnetic field is formed between the upper magnetic seat (2.1) and the lower magnetic seat (3.1). The annular magnetic field forms an orientation magnetic field between the top block (3.2) and the shaping block (2.2) for magnetically orienting the thin-film magnet.

2. The magnetizing mold for injection molding of a thin sheet magnet according to claim 1, characterized in that: The main body comprises an injection port (4) and an injection channel (5); the injection port (4) is arranged vertically, and the injection channel (5) is arranged horizontally between the injection port (4) and the mold cavity (1).

3. The magnetizing mold for injection molding of a thin sheet magnet according to claim 2, characterized in that: There are a plurality of the mold cavities (1), there is only one injection port (4), and the plurality of mold cavities (1) are arranged in a uniform array along the circumference of the injection port (4).

4. The magnetizing mold for injection molding of a thin sheet magnet according to claim 3, characterized in that: The shaping block (2.2) is annular and sleeved on the outer wall of the injection port (4); the upper magnetic seat (2.1) is annular and sleeved on the shaping block (2.2); and the magnetic field of the upper magnetic seat (2.1) is distributed along the radial direction.

5. The magnetizing mold for injection molding of a thin sheet magnet according to claim 4, characterized in that: The lower magnetic seat (3.1) is provided with a plurality of ejector blocks (3.2) corresponding one to one with the mold cavity (1), and the lower magnetic seat (3.1) is also provided with an ejector column (6) corresponding to the injection port (4), and the ejector column (6) is used to eject the injection material at the connection between the injection port (4) and the injection runner (5).

6. The magnetizing mold for injection molding of a thin sheet magnet according to claim 5, characterized in that: During injection molding, the top end height of the ejector column (6) is lower than the height of the injection molding runner (5).

7. The magnetizing mold for injection molding of a thin sheet magnet according to claim 4, characterized in that: The magnetic field of the lower magnetic seat (3.1) is also distributed in the radial direction, and the direction of the magnetic field is opposite to the direction of the magnetic field of the upper magnetic seat (2.1).

8. The magnetizing mold for injection molding of a thin sheet magnet according to claim 7, characterized in that: An annular magnetic steel (8) is provided between the upper magnetic seat (2.1) and the lower magnetic seat (3.1); the magnetic steel (8) is provided on the outer ring of the lower magnetic seat (3.1); the two poles of the magnetic steel (8) are respectively provided at the upper and lower ends of the magnetic steel (8); and the upper end of the mold cavity (1) is not higher than the upper end of the magnetic steel (8), and the lower end of the mold cavity (1) is not lower than the lower end of the magnetic steel (8).

9. The magnetizing mold for injection molding of a thin sheet magnet according to claim 8, characterized in that: The body further comprises a magnetic beam layer (9), the magnetic beam layer (9) being made of a non-magnetic hard material, and the magnetic beam layer (9) being arranged on the outer ring of the upper mold (2), the lower mold (3) and the magnetic steel (8) and wrapping the upper mold (2), the lower mold (3) and the magnetic steel (8).

10. The magnetizing mold for injection molding of a thin sheet magnet according to claim 8, characterized in that: The inner ring of the upper magnetic seat (2.1) abuts against the lower magnetic seat (3.1).

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