Magnet, manufacturing method thereof and segmented pressing die

Abstract

The invention provides a magnet, a manufacturing method thereof and a segmented pressing mold. The embodiment of the invention provides a method for manufacturing a magnet, and the method comprises the steps that a first pressing process is carried out based on a first magnet raw material to form a first annular body, the pressure direction of the first pressing process is along the axial direction of the first annular body, and the step of forming the first annular body comprises the steps that a connecting part is formed at the upper end of the first annular body; a second pressing process is carried out based on a second magnet raw material stacked on the first annular body to form a second annular body, the pressure direction of the second pressing process is in the axial direction of the first annular body, and the second magnet raw material and the first magnet raw material both comprise a magnetic material and a resin material; and the second annular body and the first annular body are connected through a connecting part. Sectional pressing is beneficial for increasing the density of the first annular body and the second annular body, and meanwhile, is beneficial for reducing the difference of sections of the first annular body and the second annular body. And through the connection of the connecting part, the magnet with a relatively high height can be better formed.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic material manufacturing, and particularly to a magnet, a manufacturing method thereof, and a segmented pressing die. Background Art

[0002] Bonded magnets have the characteristics of high forming accuracy and net-size forming, and have become indispensable important components in modern high-tech products. Bonded magnets have replaced ferrite and are widely used in small drive motors, such as the start-stop motor of the car trunk and the seat adjustment motor. With the development of bonded magnets towards miniaturization and light weight, it is required that the wall thickness of the bonded magnet is thinner and the height is higher.

[0003] The forming processes of bonded magnets can basically be divided into four types: calendering forming, injection molding, extrusion molding, and compression molding. Among them, the most commonly used are injection molding and compression molding. Compression molding refers to the process of loading metal powder or a mixture into a female mold cavity and applying pressure to the powder through a punch to press a blank with a certain shape, size, porosity, and strength.

[0004] Currently, a one-time forming process is used to press bonded magnets. However, when the magnet formed has a relatively high height and a relatively thin wall thickness, the density difference of each cross-section of the magnet is large and the overall density of the magnet is low. Summary of the Invention

[0005] In view of this, it is necessary to provide a method for manufacturing a magnet to solve the problems that when the magnet formed has a relatively high height and a relatively thin wall thickness, the density difference of each cross-section of the magnet is large and the overall density of the magnet is low.

[0006] An embodiment of the present disclosure provides a method for manufacturing a magnet, the method including: performing a first pressing process on a first magnet raw material to form a first annular body, the pressure direction of the first pressing process being along the axial direction of the first annular body, wherein the step of forming the first annular body includes: forming a connecting portion at the upper end of the first annular body; performing a second pressing process on a second magnet raw material stacked on the first annular body to form a second annular body, the pressure direction of the second pressing process being along the axial direction of the first annular body, and both the second magnet raw material and the first magnet raw material include a magnetic material and a resin material; and connecting the second annular body and the first annular body through the connecting portion.

[0007] In the method for manufacturing a magnet provided by the embodiment of the present disclosure, when forming a magnet with a relatively thin wall thickness, the first annular body and the second annular body are pressed in segments, which is beneficial to increasing the density of the first annular body and the second annular body, and at the same time is beneficial to reducing the cross-section difference of the first annular body and the second annular body. The second annular body is stacked on the first annular body and the first annular body and the second annular body are connected through the connecting portion, which can better form a magnet with a relatively high height.

[0008] In some embodiments, the step of forming the connecting portion includes: forming a groove with a groove depth ranging from 0.6 mm to 1.2 mm and a groove width greater than or equal to 1 mm.

[0009] With such a setting, the groove of the first annular body is relatively large, facilitating the natural meshing connection of the concave-convex type between the first annular body and the second annular body, and the connection method is simple and economical.

[0010] In some embodiments, the step of forming the connecting portion includes: forming an adhesive layer covering the upper surface of the first annular body.

[0011] With such a setting, the first annular body and the second annular body are connected through the adhesive layer, increasing the firmness of the connection part.

[0012] In some embodiments, the steps of forming the first annular body and the second annular body include: forming a first through hole penetrating the first annular body; the step of forming the second annular body includes: forming a second through hole penetrating the second annular body. The step of connecting the second annular body and the first annular body through the connecting portion includes: passing a connecting rod through the second through hole and the first through hole.

[0013] With such a setting, the connecting rod passes through the first through hole and the second through hole, facilitating the fixation of the first annular body and the second annular body.

[0014] In some embodiments, the method for manufacturing a magnet further includes: curing the first annular body and the second annular body; the curing temperature range is from 150 °C to 220 °C, and the curing time is greater than or equal to 60 minutes.

[0015] With such a setting, due to the presence of the resin, the first annular body and the second annular body expand during the curing process, which is beneficial to the connecting portion tightly connecting the first annular body and the second annular body, improving the fastening property of the magnet.

[0016] In some embodiments, the stacking height of the first magnet raw material is less than or equal to 10 mm, and the stacking height of the second magnet raw material is less than or equal to 10 mm. The pressure range of the first pressing process is 8 T / cm 2 to 12 T / cm 2 , and the pressing frequency is from ten pieces per minute to forty pieces per minute; the pressure range of the second pressing process is 8 T / cm 2 to 12 T / cm 2 , and the pressing frequency is from ten pieces per minute to forty pieces per minute.

[0017] With such a setting, the first annular body and the second annular body formed by pressing have a high density, and it is beneficial to reduce the difference in the cross-sectional dimensions of the first annular body and the second annular body, making the difference in the cross-sectional dimensions less than 0.04 mm.

[0018] In some embodiments, the loose bulk density of the first magnet material and the loose bulk density of the second magnet material are both less than 3 g / cm 3 , and the density ranges of the first annular body and the second annular body are both 5.9 g / cm 3 to 6.1 g / cm 3 .

[0019] In the case where the loose bulk ratios of the magnet materials are the same, the densities of the first annular body and the second annular body formed by this method are greater than the density of the product formed by one-time pressing, and at the same time, the height of the magnet stacked by this method is also higher than that of the magnet formed by one-time molding.

[0020] Embodiments of the present disclosure provide a segmented pressing die for performing the above method. The segmented pressing die includes: an upper punch, a lower punch, a die, and a mandrel. The lower punch is sleeved on the outer wall of the mandrel, the die is sleeved on the outer wall of the lower punch, and the upper surface of the lower punch is lower than the upper surface of the die and lower than the upper surface of the mandrel to define a cavity; the upper punch is used to apply pressure. Exemplarily, a plurality of small protrusions are provided on the lower end surface of the lower punch.

[0021] The segmented pressing die provided by the embodiments of the present disclosure is conducive to multiple filling and multiple pressing and forming. The reduction of the height of the die is conducive to reducing the processing difficulty of the segmented pressing die. Under a fixed number of forming times, selecting the lowest die height can save the cost of the die.

[0022] Embodiments of the present disclosure provide a magnet, which is obtained by the steps of the above method for manufacturing a magnet. Alternatively, the magnet is pressed according to the above segmented pressing die.

[0023] The magnet provided by the embodiments of the present disclosure manufactured by the above method or the above die has a relatively high height, a relatively thin wall thickness, a small difference in cross-sectional dimensions, and a relatively large density.

[0024] In some embodiments, the height of the magnet is greater than 40 mm, the wall thickness is less than 3 mm, the difference in cross-sectional dimensions of the magnet is less than or equal to 0.02 mm, and the density range of the magnet is 5.9 g / cm 3 to 6.1 g / cm 3 .

[0025] Compared with the magnet formed by one-time pressing, the magnet formed by this segmented pressing method has greatly improved performance in all aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flowchart of the method for manufacturing a magnet in an embodiment of the present disclosure;

[0027] Figure 2 is a schematic cross-sectional dimension diagram of a magnet with one-way pressing by a one-time pressing method;

[0028] Figure 3 Schematic cross-sectional dimension diagram of a magnet with bidirectional pressing by a one-step pressing method;

[0029] Figure 4 Schematic cross-sectional dimension diagram of a magnet pressed by the method for manufacturing a magnet in an embodiment of the present disclosure;

[0030] Figure 5 Exploded structure schematic diagram of a segmented pressing die in an embodiment of the present disclosure;

[0031] Figure 6 Schematic cross-sectional view of the first filling and the first forming in the method steps for manufacturing a magnet in an embodiment of the present disclosure;

[0032] Figure 7 Schematic cross-sectional view of the second filling and the second forming in the method steps for manufacturing a magnet in an embodiment of the present disclosure;

[0033] Figure 8 Schematic cross-sectional view of the third filling and the third forming in the method steps for manufacturing a magnet in an embodiment of the present disclosure;

[0034] Figure 9 Schematic cross-sectional view of the final forming of the magnet in the method steps for manufacturing a magnet in an embodiment of the present disclosure;

[0035] Figure 10 Schematic structure diagram of a magnet in an embodiment of the present disclosure;

[0036] Figure 11 Schematic structure diagram of a magnet in another embodiment of the present disclosure.

[0037] Reference numerals: 10, segmented pressing die; 1, upper punch; 2, female die; 3, lower punch; 4, mandrel; 11, first magnet raw material; 12, second magnet raw material; 13, third magnet raw material; 20, magnet; 21, first annular body; 22, second annular body; 23, third annular body; 201, connecting portion; 2011, groove; 2012, first through hole. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

[0039] It should be noted that when a component is referred to as "installed on" another component, it can be directly on the other component or there can also be an intermediate component. When a component is considered to be "arranged on" another component, it can be directly arranged on the other component or there may be an intermediate component at the same time. When a component is considered to be "fixed to" another component, it can be directly fixed to the other component or there may be an intermediate component at the same time.

[0040] The structural dimensions shown in the drawings in this article do not represent the actual dimensions and may be adjusted according to needs during actual production. The orientation terms such as "upper", "lower", "left", and "right" used in this article refer to the orientation in the drawings and should not be regarded as a limitation on the product during actual use unless clearly stated.

[0041] The first, second, third, etc. in this article are only used to distinguish the same features. It can be understood that the third annular body in this article can also be called the second annular body, and the second annular body can also be called the first annular body.

[0042] Unless otherwise defined, all technical and scientific terms used in this article have the same meaning as those commonly understood by those skilled in the technical field to which this disclosure belongs. The terms used in the description of this disclosure in this article are only for the purpose of describing specific embodiments and are not intended to limit this disclosure. The term "or / and" used in this article includes any and all combinations of one or more related listed items.

[0043] With the development of bonded magnets towards miniaturization and light weight, it is required that the wall thickness of the bonded magnets be thinner and the height be higher. Currently, a one-step forming process is used to press bonded magnets. Refer to Figure 2 For the magnet pressed by the one-step forming process with unidirectional pressing, the cross-sectional shape is conical. Refer to Figure 3 For the magnet pressed by the one-time forming process with bidirectional pressing, the cross-sectional shape is flared. This is because during forming, the pressure applied externally results in different pressures on each cross-section of the magnet due to the presence of sidewall friction, making the density of each cross-section different; further causing different elastic aftereffect effects on each cross-section; and further resulting in different dimensions of each cross-section. Therefore, when the height of the magnet formed by pressing is higher and the wall thickness is thinner, the size difference of each cross-section of the magnet is more obvious, and the overall density of the magnet is lower and more uneven.

[0044] Based on this, in view of the above problems, a method 1000 for manufacturing a magnet is provided.

[0045] Refer to Figure 1 , Figure 1 shows the flow of the method 1000 for manufacturing a magnet in the embodiments of this disclosure. The method 1000 for manufacturing a magnet provided by the embodiments of this disclosure includes the following steps S101 to step S103. The following combinesFigures 5 to 9 Describe method 1000 for manufacturing a magnet according to an embodiment of the present disclosure.

[0046] Step S101: Perform a first pressing process on the first magnet raw material 11 to form a first annular body 21. The pressure direction of the first pressing process is along the axial direction of the first annular body 21. Exemplarily, a connecting portion 201 is formed at the upper end of the first annular body 21 during the first pressing process.

[0047] Step S102: Perform a second pressing process on the second magnet raw material 12 stacked on the first annular body 21 to form a second annular body 22. The pressure direction of the second pressing process is along the axial direction of the first annular body 21. Exemplarily, both the second magnet raw material 12 and the first magnet raw material 11 include a magnetic material and a resin material; the second annular body 22 is formed at the upper end of the first annular body 21.

[0048] Step S103: Connect the second annular body 22 and the first annular body 21 through the connecting portion 201.

[0049] In the method 1000 for manufacturing a magnet provided by the embodiment of the present disclosure, a certain height of the first magnet raw material 11 is stacked, and the first magnet raw material 11 is pressed along the axial direction of the to-be-formed first annular body 21 by the first pressing process to form the first annular body 21, and at the same time, the connecting portion 201 is formed at the upper end of the first annular body 21. Since the stacking height of the first magnet raw material 11 is relatively low, the friction force generated by the externally applied pressure on the side wall is relatively uniform, and the pressure received by each cross-section of the first annular body 21 is relatively uniform, so that the density of each cross-section is relatively uniform; furthermore, the elastic aftereffect of each cross-section is relatively the same; furthermore, the size difference of each cross-section is relatively small, and the first annular body 21 has a high density and a uniform density.

[0050] Then, a certain height of the second magnet raw material 12 is stacked on the upper end of the first annular body 21, and the second magnet raw material 12 is pressed along the axial direction of the first annular body 21 by the second pressing process to form the second annular body 22. Since the stacking height of the second magnet raw material 12 is relatively low, the friction force generated by the externally applied pressure on the side wall is relatively uniform, and the pressure received by each cross-section of the second annular body 22 is relatively uniform, so that the density of each cross-section is relatively uniform; furthermore, the elastic aftereffect of each cross-section is relatively the same; furthermore, the size difference of each cross-section is relatively small, and the second annular body 22 has a high density and a uniform density.

[0051] Connect the first annular body 21 and the second annular body 22 through the connecting portion 201. Among them, both the first magnet raw material 11 and the second magnet raw material 12 include a magnetic material and a resin material.

[0052] The method for manufacturing a magnet provided by the embodiments of the present disclosure is easy to implement, and the manufactured product has good performance and reliable quality. In addition, a magnetic ring with a relatively high height and high precision can be realized by means of a mold with a non-compliant height dimension.

[0053] Refer to Figure 4 , when forming the magnet 20 with a relatively thin wall thickness, the first annular body 21 and the second annular body 22 are pressed in sections, which is beneficial to increasing the density of the first annular body 21 and the second annular body 22, and at the same time is beneficial to reducing the sectional differences of the first annular body 21 and the second annular body 22. The second annular body 22 is stacked on the first annular body 21, and the first annular body 21 and the second annular body 22 are connected through the connecting portion 201, so that a magnet 20 with a relatively high height can be better formed.

[0054] Exemplarily, the method 1000 for manufacturing a magnet provided by the embodiments of the present disclosure further includes performing a third pressing process on the third magnet raw material 13 stacked on the second annular body 22 to form a third annular body 23. The second pressing process forms a connecting portion 201 at the upper end of the second annular body 22, and the third annular body 23 and the second annular body 22 are connected through the connecting portion 201. It can be understood that when the height requirement of the magnet 20 is relatively high. A magnetic raw material can be stacked on the formed annular body to press and form the next annular body, and this step can be repeated multiple times to obtain the target magnet 20.

[0055] In other embodiments, the step of forming the second annular body 22 includes: forming a matching portion for the connecting portion 201 at the lower end of the second annular body 22 while forming the connecting portion 201 at the upper end of the second annular body 22.

[0056] Exemplarily, the first pressing process is the same as the second pressing process, and the first annular body 21 is the same as the second annular body 22. In other embodiments, the second annular body 22 can be different from the first annular body 21.

[0057] In the method 1000 for manufacturing a magnet provided by the embodiments of the present disclosure, step S102 and step S103 can be executed simultaneously. In other embodiments, step S102 can be executed first, and then step S103 can be executed.

[0058] Exemplarily, the magnetic material can be at least one of neodymium iron boron magnetic powder, ferrite powder, samarium iron nitride powder or composite magnetic powder.

[0059] Exemplarily, the resin material is a thermosetting resin, which can be supplemented with a small amount of curing agent and coupling agent. Exemplarily, the resin material is an epoxy resin.

[0060] In some embodiments, the step of forming the connecting portion 201 includes: forming a groove 2011 with a groove depth ranging from 0.6 mm to 1.2 mm and a groove width greater than or equal to 1 mm.

[0061] With such a setting, the groove 2011 of the first annular body 21 is relatively large, facilitating the natural meshing connection of the concave-convex type between the first annular body 21 and the second annular body 22, and the connection method is simple and economical.

[0062] Exemplarily, two grooves 2011 may be formed on the upper part of the first annular body 21. In other embodiments, there may be multiple grooves 2011, and the number of grooves 2011 is not limited.

[0063] Exemplarily, the groove 2011 penetrates through the first annular body 21 in a direction perpendicular to the axial direction of the first annular body 21. In other embodiments, the groove 2011 does not penetrate through the first annular body 21 in a direction perpendicular to the axial direction of the first annular body 21.

[0064] It can be understood that the shape and size of the groove 2011 are determined according to the shape and size of the annular body, and the groove 2011 needs to avoid the functional area of the magnet 20.

[0065] In other embodiments, the step of forming the connecting portion 201 further includes: forming a protrusion matching the groove 2011 at the lower end of the second annular body 22 while forming a groove 2011 at the upper end of the second annular body 22.

[0066] In some embodiments, the step of forming the connecting portion 201 includes: forming an adhesive layer covering the upper surface of the first annular body 21.

[0067] With such a setting, the first annular body 21 and the second annular body 22 are connected through the adhesive layer, increasing the firmness of the connection part.

[0068] In some embodiments, the steps of forming the first annular body 21 and the second annular body 22 include: forming a first through hole 2012 penetrating through the first annular body 21, and forming a second through hole penetrating through the second annular body 22. The step of connecting the second annular body 22 and the first annular body 21 through the connecting portion 201 includes: inserting a connecting rod through the second through hole and the first through hole 2012.

[0069] With such a setting, the connecting rod is inserted through the first through hole 2012 and the second through hole, facilitating the fixation of the first annular body 21 and the second annular body 22.

[0070] Exemplarily, there are two first through holes 2012, symmetrically distributed on the first annular body 21. There are two second through holes, symmetrically distributed on the second annular body 22.

[0071] Exemplarily, the shape of the first through hole 2012 and the shape of the second through hole are both circular. In other embodiments, the shape of the first through hole 2012 and the shape of the second through hole are both square or other shapes.

[0072] It can be understood that the number of the first through holes 2012 is the same as that of the second through holes, and the shape and position of the second through holes are correspondingly arranged with those of the first through holes 2012.

[0073] Refer to again Figure 1 , in some embodiments, the method 1000 for manufacturing a magnet further includes step S104: curing the first annular body 21 and the second annular body 22; the curing temperature range is 150 °C to 220 °C, and the curing time is greater than or equal to 60 minutes.

[0074] With such an arrangement, due to the presence of the resin, the first annular body 21 and the second annular body 22 expand during the curing process, which is beneficial to the connecting portion 201 tightly connecting the first annular body 21 and the second annular body 22, and improves the fastening property of the magnet 20.

[0075] Exemplarily, the protrusion of the second annular body 22 expands through a curing reaction and is more tightly fixedly connected to the groove 2011 of the first annular body 21.

[0076] In the method 1000 for manufacturing a magnet provided by the embodiments of the present disclosure, step S102 and step S103 can be executed simultaneously, and then step S104 is executed. In other embodiments, step S103 can be executed after executing step S102 and step S104. In still other embodiments, step S102 and step S103 can be executed first, and then step S104 is executed.

[0077] In some embodiments, the stacking height of the first magnet raw material 11 is less than or equal to 10 mm, and the stacking height of the second magnet raw material 12 is less than or equal to 10 mm;

[0078] The pressure range of the first pressing process is 8 T / cm 2 -12 T / cm 2 , and the pressing frequency range is from ten pieces per minute to forty pieces per minute; the pressure range of the second pressing process is 8 T / cm 2 -12 T / cm 2 , and the pressing frequency range is from ten pieces per minute to forty pieces per minute.

[0079] With such an arrangement, the first annular body 21 and the second annular body 22 formed by pressing have a high density, and it is beneficial to reduce the difference in the cross-sectional dimensions of the first annular body 21 and the second annular body 22, so that the difference in the cross-sectional dimensions is less than 0.04 mm.

[0080] Exemplarily, the stacking height of the first magnet raw material 11 is 10 mm, and the stacking height of the second magnet raw material 12 is also 10 mm. In other embodiments, the stacking height of the first magnet raw material 11 and the stacking height of the second magnet raw material 12 can be different.

[0081] Generally, when the density Σ1 of the magnet 20 is 6, the upper limit hm of the stacking height of the raw material of the magnet 20, the density Σ1 of the magnet 20, the height h1 of the female mold 2, and the loose bulk density Σ2 of the raw material of the magnet 20 satisfy: hm ≥ 6×(h1 - 10 mm) / Σ2, and the loose bulk ratio of the raw material of the magnet 20 is 2.9 g / cm 3 to 3.1 g / cm 3 , and the stacking height of the raw material of the magnet 20 each time can be confirmed according to the actual use.

[0082] The pressing time using mechanical pressing is relatively short. Exemplarily, the pressing frequency is 15 pieces / minute. In other embodiments, a hydraulic press can also be used for pressing, and the pressing frequency is 10 pieces / minute.

[0083] Exemplarily, the dimensional difference of each cross-section is less than or equal to 0.01 mm. In other embodiments, the dimensional difference of each cross-section can be less than or equal to 0.02 mm.

[0084] It can be understood that the function of the pressing pressure is to compact the raw material of the magnet 20. As the pressure increases, the density of the formed annular body will also increase, but after reaching a certain pressure, the density of the formed annular body will basically not change.

[0085] It can be understood that the index of the pressing speed is also the time required to compact the raw material of the magnet 20. The higher the height of the annular body formed by one-time pressing, the more time is required.

[0086] Exemplarily, the temperature of the mold and the temperature of the raw material of the magnet 20 will also affect the density of the formed magnet 20. The pressing temperature can be normal temperature, or warm pressing. The temperature of the mold and the raw material of the magnet 20 under constant pressure is 100°C to 130°C, and warm pressing can increase the density of the formed magnet 20, and the increased density range is 0.1 g / cm 3 to 0.3 g / cm 3 .

[0087] In some embodiments, the loose bulk density of the first magnet raw material 11 and the loose bulk density of the second magnet raw material 12 are based on the actual situation of the raw materials, for example, 2.8 g / cm 3 . The density range of the first annular body 21 and the second annular body 22 is 5.9 g / cm 3 to 6.1 g / cm 3 .

[0088] In the case where the loose bulk ratio of the raw material of the magnet 20 is the same, the density of the first annular body 21 and the second annular body 22 formed by this method is greater than the density of the product formed by one-time pressing, and at the same time, the height of the magnet 20 stacked by this method is also higher than that of the magnet 20 formed by one-time pressing.

[0089] Exemplarily, the loose bulk density of the first magnet raw material 11 is 2.8 g / cm 3 , the stacking height of the first magnet raw material 11 is 10 mm, and the pressure of the first pressing process is 8 T / cm 2 , the pressing frequency is ten pieces per minute, and at room temperature, a first annular body 21 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained. A groove 2011 with a groove depth of 0.6 mm and a groove width equal to 1 mm is formed at the upper end of the first annular body 21. On the first annular body 21, a second magnet raw material 12 with a stacking height of 10 mm and a loose bulk density of 2.8 g / cm 3 is stacked. The pressure of the second pressing process is 8 T / cm 2 , the pressing frequency is ten pieces per minute, and at room temperature, a second annular body 22 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained. A protrusion matching the groove 2011 is formed at the lower end of the second annular body 22, and a groove 2011 is formed at the upper end of the second annular body 22. The cooperation between the protrusion and the groove 2011 of the first annular body 21 connects the first annular body 21 and the second annular body 22. The first annular body 21 and the second annular body 22 are cured; the curing temperature is 150 °C and the curing time is 60 minutes, and finally the magnet 20 is formed.

[0090] Exemplarily, the loose bulk density of the first magnet raw material 11 is 2.8 g / cm 3 , the stacking height of the first magnet raw material 11 is 10 mm, and the pressure of the first pressing process is 10 T / cm 2 , the pressing frequency is thirty pieces per minute, and at room temperature, a first annular body 21 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained. Then, an adhesive layer covering the upper surface of the first annular body 21 is formed; on the adhesive layer on the upper surface of the first annular body 21, a second magnet raw material 12 with a stacking height of 10 mm and a loose bulk density of 2.8 g / cm 3 is stacked. The pressure of the second pressing process is 10 T / cm 2 , the pressing frequency is thirty pieces per minute, and at room temperature, a second annular body 22 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained; the first annular body 21 and the second annular body 22 are cured; the curing temperature is 180 °C and the curing time is 60 minutes, and finally the magnet 20 is formed.

[0091] Exemplarily, the loose bulk density of the first magnet raw material 11 is 2.8 g / cm 3, the stacking height of the first magnet raw material 11 is 10 mm, and the pressure of the first pressing process is 12 T / cm 2 , the pressing frequency is forty pieces per minute. At room temperature, a first annular body 21 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained, and a first through hole 2012 penetrating the first annular body 21 is formed; on the first annular body 21, the stacking height is 10 mm and the loose density is 2.8 g / cm 3 of the second magnet raw material 12. The pressure of the second pressing process is 12 T / cm 2 , the pressing frequency is forty pieces per minute. At room temperature, a second annular body 22 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained, and a second through hole penetrating the second annular body 22 is formed; the first annular body 21 and the second annular body 22 are cured; the curing temperature is 220 °C and the curing time is 60 minutes. Then, a connecting rod is inserted through the second through hole and the first through hole 2012, and finally the magnet 20 is formed.

[0092] In other embodiments, a third magnet raw material 13 with a stacking height of 10 mm and a loose density of 2.8 g / cm 3 can also be stacked on the second annular body 22. The pressure range of the third pressing process is 8 T / cm 2 to 12 T / cm 2 , the pressing frequency range is ten pieces per minute to forty pieces per minute. At room temperature, a third annular body 23 with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained... until the Nth magnet 20 raw material with a stacking height of 10 mm and a loose density of 2.8 g / cm 3 is stacked on the (N - 1)th annular body. The pressure range of the Nth pressing process is 8 T / cm 2 to 12 T / cm 2 , the pressing time range is 10 minutes to 40 minutes. At room temperature, an Nth annular body with a density range of 5.9 g / cm 3 to 6.1 g / cm 3 is obtained, and the magnet 20 is formed by curing N annular bodies.

[0093] Refer to Figure 5 , the present disclosure provides a segmented pressing die 10 for performing the above method. The segmented pressing die 10 includes: an upper punch 1, a lower punch 3, a die 2, and a mandrel 4. The lower punch 3 is sleeved on the outer wall of the mandrel 4, the die 2 is sleeved on the outer wall of the lower punch 3, and the upper surface of the lower punch 3 is lower than the upper surface of the die 2 and lower than the upper surface of the mandrel 4 to define a cavity; the upper punch 1 is used to apply pressure.

[0094] In the one-step forming process, the height h1 of the female mold 2, the height h2 of the magnet 20, the density Σ1 of the magnet 20, and the loose packing density Σ2 of the raw material of the magnet 20 satisfy: h1 ≥ h2 * Σ1 / Σ2 + 20 mm. Exemplarily, the density of the magnet 20 is 6.0 g / cm 3 , and the loose packing density of the raw material of the magnet 20 is 2.8 g / cm 3 . When the height of the magnet 20 is above 50 mm, the height of the female mold 2 should be above 108 mm. The dimensional accuracy requirement of the cavity of the female mold 2 is within 0.006 mm. The higher the height of the female mold 2, the greater the processing difficulty and the higher the processing cost. Even based on the existing processing technology, the designed mold cannot be processed.

[0095] The segmented pressing mold 10 provided by the embodiments of the present disclosure can be used to execute the foregoing method 1000, which is beneficial to multiple fillings and multiple pressing and forming. The reduction of the height of the female mold 2 is beneficial to reducing the processing difficulty of the segmented pressing mold 10. Under a fixed number of forming times, selecting the lowest height of the female mold 2 can save the cost of the mold.

[0096] Exemplarily, a plurality of small protrusions are provided on the lower end surface of the lower punch 3.

[0097] Referring to Figures 6 to 9 , exemplarily, the lower punch 3 is sleeved on the outer wall of the mandrel 4, the female mold 2 is sleeved on the outer wall of the lower punch 3, the upper surface of the mandrel 4 is flush with the upper surface of the female mold 2, and the upper surface of the lower punch 3 is 10 mm lower than the upper surface of the female mold 2, forming a cavity of 10 mm; the first magnet raw material 11 with a loose packing density of 2.8 g / cm 3 is stacked inside the cavity. At room temperature, the upper punch 1 of the first pressing process with a pressure of 8 T / cm 2 and a pressing frequency of ten per minute moves downward, and the end of the upper punch 1 gradually enters the inside of the female mold 2, obtaining a first ring body 21 with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3 ; the upper punch 1 is taken out from the upper part of the female mold 2. After covering an adhesive layer (not shown) on the upper surface of the formed first ring body 21, the lower punch 3 moves downward until the upper end of the first ring body 21 is 10 mm away from the upper end of the female mold 2 and stops. Then, the second magnet raw material 12 with a loose packing density of 2.8 g / cm 3 is continuously stacked inside the 10-mm cavity. At room temperature, the upper punch 1 of the second pressing process with a pressure of 8 T / cm 2 and a pressing frequency of ten per minute moves downward, and the end of the upper punch 1 gradually enters the inside of the female mold 2, obtaining a second ring body with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3The second annular body 22 is taken out from the upper part of the female die 2, and the upper punch 1 is taken out. A glue layer is covered on the upper surface of the formed second annular body 22; and so on, the third annular body 23 to the thirteenth annular body are formed. Then, the upper punch 1 remains stationary, and the first annular body 21 to the thirteenth annular body stacked and connected in sequence are cured; the curing temperature is 150 °C, and the curing time is 60 minutes, and finally the magnet 20 is formed.

[0098] Refer to Figures 6 to 10 , exemplarily, the lower punch 3 is sleeved on the outer wall of the mandrel 4, the female die 2 is sleeved on the outer wall of the lower punch 3, the upper surface of the mandrel 4 is flush with the upper surface of the female die 2, and the upper surface of the lower punch 3 is 10 mm lower than the upper surface of the female die 2, forming a cavity of 10 mm; the first magnet raw material 11 with a loose packing density of 2.8 g / cm 3 is stacked inside the cavity. At room temperature, the upper punch 1 of the first pressing process with a pressure of 12 T / cm 2 and a pressing frequency of forty per minute moves downward, and the end of the upper punch 1 gradually enters the inside of the female die 2, obtaining the first annular body 21 with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3 , and a groove 2011 with a groove depth of 1 mm and a groove width of 1 mm is formed at the upper end of the first annular body 21; after the upper punch 1 is taken out from the upper part of the female die 2, the lower punch 3 moves downward until it stops when the upper end of the first annular body 21 is 10 mm away from the upper end of the female die 2. Then, the second magnet raw material 12 with a loose packing density of 2.8 g / cm 3 is continuously stacked inside the 10 mm cavity. At room temperature, the upper punch 1 of the second pressing process with a pressure of 12 T / cm 2 and a pressing frequency of forty per minute moves downward, and the end of the upper punch 1 gradually enters the inside of the female die 2, obtaining the second annular body 22 with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3 , and a protrusion matching the groove 2011 is formed at the lower end of the second annular body 22, and at the same time, a groove 2011 is formed at the upper end of the second annular body 22. The cooperation between the protrusion and the groove 2011 of the first annular body 21 connects the first annular body 21 and the second annular body 22; and so on, the third annular body 23 to the thirteenth annular body are formed. Then, the upper punch 1 remains stationary, and the first annular body 21 to the thirteenth annular body stacked and connected in sequence are cured; the curing temperature is 220 °C, and the curing time is 60 minutes, and finally the magnet 20 is formed. The method of using the cooperation of the groove 2011 is the most natural and economical.

[0099] Refer to Figures 6 to 9 and Figure 11, Exemplarily, the lower punch 3 is sleeved on the outer wall of the mandrel 4, and the die 2 is sleeved on the outer wall of the lower punch 3. The upper surface of the mandrel 4 is flush with the upper surface of the die 2, and the upper surface of the lower punch 3 is 10 mm lower than the upper surface of the die 2, forming a cavity of 10 mm; the first magnet raw material 11 with a loose packing density of 2.8 g / cm 3 is stacked inside the cavity. At room temperature, the upper punch 1 of the first pressing process with a pressure of 10 T / cm 2 and a pressing frequency of thirty per minute moves downward, and the end of the upper punch 1 gradually enters the die 2, obtaining a first annular body 21 with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3 , and a first through hole 2012 penetrating the first annular body 21 is formed; after the upper punch 1 is taken out from the upper part of the die 2, the lower punch 3 moves downward until the upper end of the first annular body 21 is 10 mm away from the upper end of the die 2 and stops. Then, the second magnet raw material 12 with a loose packing density of 2.8 g / cm 3 is continuously stacked inside the 10-mm cavity. At room temperature, the upper punch 1 of the second pressing process with a pressure of 10 T / cm 2 and a pressing frequency of thirty per minute moves downward, and the end of the upper punch 1 gradually enters the die 2, obtaining a second annular body 22 with a height of 4.67 mm and a density range of 5.9 g / cm 3 to 6.1 g / cm 3 , and a first through hole 2012 penetrating the first annular body 21 is formed; and so on, a third annular body 23 to a thirteenth annular body are formed. Then, the upper punch 1 remains stationary, and the first annular body 21 to the thirteenth annular body stacked and connected in sequence are cured; the curing temperature is 180 °C, and the curing time is 60 minutes. Then, the connecting rod is inserted through the first through hole 2012 to the thirteenth through hole, and finally the magnet 20 is formed. The method uses a connecting rod for convenient connection operation.

[0100] In other embodiments, the stacking height of the magnet 20 raw material each time can be different, the pressing process is the same, and the heights of the annular bodies obtained after pressing are different but the densities are the same.

[0101] It can be understood that the height of the die 2 and the stacking height of the magnet 20 raw material each time can be actively adjusted. On the premise of meeting the dimensional accuracy of the formed magnet 20, the minimum number of forming times can be selected. Or, under the condition of a fixed number of forming times, the lowest height of the die 2 can be selected.

[0102] The present disclosure provides a magnet 20, which is obtained by the steps of the method 1000 for manufacturing a magnet described above. Or, the magnet 20 is obtained by pressing according to the segmented pressing die 10 described above.

[0103] The magnet 20 manufactured by the above method or the above mold provided by the embodiments of the present disclosure has a relatively high height, a relatively thin wall thickness, small differences in cross-sectional dimensions, and a relatively high density.

[0104] In some embodiments, the height of the magnet 20 is greater than 40 mm, the wall thickness is less than 3 mm, the difference in cross-sectional dimensions of the magnet 20 is less than or equal to 0.02 mm, and the density range of the magnet 20 is 5.9 g / cm 3 to 6.1 g / cm 3 .

[0105] In some comparative examples, when the loose packing ratio of the raw material of the magnet 20 is 2.8 g / cm 3 , and the height of the female mold 2 is 80 mm, the maximum height of the magnet 20 formed by one-time pressing is 32.7 mm, the density of the magnet 20 is 5.8 g / cm 3 , the inner and outer diameters at both axial ends of the magnet 20 are large, and the inner and outer diameters in the middle are small, and the dimensional difference reaches 0.88 mm.

[0106] In the embodiments of the present disclosure, when the loose packing ratio of the raw material of the magnet 20 is 2.8 g / cm 3 , and the height of the female mold 2 is 80 mm, the maximum height of the magnet 20 formed by multiple fillings and multiple pressings is 60.71 mm, the density of the magnet 20 is 5.95 - 6.15 g / cm3, and the dimensional difference of the inner and outer diameters is within 0.04 mm.

[0107] Compared with the magnet 20 formed by one-time pressing, the magnet 20 provided by the embodiments of the present disclosure has a more uniform density, and there are greater improvements in the dimensional differences of the cross-sections of the magnet 20, the density of the magnet 20, and the height of the magnet 20.

[0108] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0109] The above various forms of processes can be used, and steps can also be reordered, added, or deleted. The steps recorded in the embodiments of the present disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solutions provided by the embodiments of the present disclosure can be achieved. This is not limited herein.

[0110] The above-described embodiments merely represent several implementation manners of the present disclosure. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the disclosed patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several variations and improvements can still be made, and these all fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure patent shall be subject to the appended claims.

Claims

1. A method for producing a magnet, characterized in that include: A first pressing process is performed based on a first magnet raw material to form a first annular body, wherein a pressure direction of the first pressing process is along an axial direction of the first annular body, wherein the step of forming the first annular body comprises: forming a connecting portion at an upper end of the first annular body; Performing a second pressing process on a second magnet raw material stacked on the first ring body to form a second ring body, wherein a pressure direction of the second pressing process is along an axial direction of the first ring body, and both the second magnet raw material and the first magnet raw material include a magnetic material and a resin material; and The second annular body and the first annular body are connected via the connecting portion.

2. The method for manufacturing a magnet according to claim 1, wherein: The step of forming the connecting portion includes: forming a groove with a groove depth ranging from 0.6 mm to 1.2 mm and a groove width greater than or equal to 1 mm.

3. The method for manufacturing a magnet according to claim 1, wherein: The step of forming the connecting portion includes: forming a glue layer covering the upper surface of the first annular body.

4. The method for manufacturing a magnet according to claim 1, wherein: The step of forming the first annular body includes: forming a first through hole penetrating the first annular body; the step of forming the second annular body includes: forming a second through hole penetrating the second annular body; The step of connecting the second annular body and the first annular body through the connecting portion includes: inserting a connecting rod through the second through hole and the first through hole.

5. The method for manufacturing a magnet according to claim 2, wherein: The method further includes: curing the first annular body and the second annular body; the curing temperature range is 150° C. to 220° C., and the curing time is greater than or equal to 60 minutes.

6. The method for manufacturing a magnet according to claim 1, wherein: The stacking height of the first magnet material is less than or equal to 10 mm, and the stacking height of the second magnet material is less than or equal to 10 mm; The pressure range of the first pressing process is 8T / cm 2 Up to 12T / cm 2 The pressing frequency ranges from ten to forty pieces per minute; the pressure range of the second pressing process is 8T / cm 2 Up to 12T / cm 2 The pressing frequency ranges from ten to forty pieces per minute.

7. The method for manufacturing a magnet according to claim 1, wherein: The bulk density of the first magnet raw material and the bulk density of the second magnet raw material are both less than 3g / cm 3 The density of the first annular body and the density of the second annular body are both in the range of 5.9 g / cm 3 Up to 6.1g / cm 3 .

8. A segmented pressing die for carrying out the method according to claims 1 to 7, characterized in that: The segmented pressing die comprises: an upper punch, a lower punch, a concave die and a core rod; The lower punch is sleeved on the outer wall of the core rod, the die is sleeved on the outer wall of the lower punch, the upper surface of the lower punch is lower than the upper surface of the die and lower than the upper surface of the core rod to define the cavity; the upper punch is used to apply pressure.

9. A magnet, characterized in that The magnet is manufactured by the steps of the method for manufacturing a magnet according to any one of claims 1 to 7 , or the magnet is pressed according to the segmented pressing mold according to claim 8 .

10. The magnet according to claim 9, wherein The height of the magnet is greater than 40 mm, the wall thickness is less than 3 mm, the difference in the cross-sectional dimensions of the magnet is less than or equal to 0.02 mm, and the density range of the magnet is 5.9 g / cm 3 Up to 6.1g / cm 3 .

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