A method for preparing a mold and a magnet with surface magnet aggregation function

Abstract

The present invention provides a mold and a magnet with surface magnetic concentration function, belonging to the technical field of permanent magnet material preparation, including: a mold cavity, including a mold cavity opening and a mold cavity bottom; a first alloy block and a second alloy block, and both the first alloy block and the second alloy block can move up and down along the opening direction of the mold cavity opening; two orientation coils, arranged in the first alloy block and located on the same horizontal plane. Among them, when opposite-direction currents are passed through the two orientation coils, the two orientation coils respectively form two magnetic fields with concentrically distributed magnetic force lines, so that the distance between any two adjacent magnetic force lines on the side close to the orientation coil is less than the distance between the corresponding two adjacent magnetic force lines on the side far from the orientation coil. In the present invention, the two orientation coils are arranged on the same side, and after passing opposite-direction currents, the density of the magnetic force lines on the side of the formed magnet in the mold cavity close to the mold cavity opening is inconsistent with that on the side close to the mold cavity bottom.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet material preparation, and relates to a mold, in particular to a mold and a magnet for preparing a magnet with surface magnetic concentration function. Background Art

[0002] Permanent magnet materials are an important type of functional materials and are indispensable in modern industry and science and technology. Due to their high magnetic energy density, they have rapidly become extremely important basic functional materials in the global high-tech industries. They have been widely used in the computer industry, automotive industry, communication and information industry, medical industry, power electronics industry, smart home industry, etc. Permanent magnets mainly include neodymium iron boron magnets (NdFeB), samarium cobalt permanent magnet alloys (SmCo), aluminum nickel cobalt permanent magnet alloys (AlNiCo), and ferrites. Neodymium iron boron permanent magnet alloys are mainly composed of neodymium (Nd), iron (Fe), and boron (B), and have extremely high magnetic energy product and remanence, and are the one with the strongest magnetic properties among the currently commercialized permanent magnet materials; samarium cobalt permanent magnet alloys are mainly composed of samarium (Sm) and cobalt (Co), and have relatively high coercivity and good temperature stability, and can maintain strong magnetic properties in high-temperature environments; aluminum nickel cobalt permanent magnet alloys are mainly composed of aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe), and have good magnetic properties and temperature stability; ferrite magnets are a type of ceramic material composed of iron oxides and other metal oxides (such as oxides of barium (Ba) or strontium (Sr)), and have relatively low magnetic energy product and remanence, but have low cost and good corrosion resistance. Different types of permanent magnets are applied in different fields due to their unique magnetic properties and cost characteristics.

[0003] With the development of informatization, the market has an increasingly high demand for the performance improvement and convenience of electronic information devices. At present, during the forming process of the permanent magnet materials used, the magnetic field lines are arranged in parallel, resulting in the same magnetic force and the same performance on both sides of the formed magnet. However, generally during use, only the performance of one side can be utilized, and the performance of the other side cannot be used, causing waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems existing in the prior art and propose a mold for preparing a magnet with surface magnetic concentration function that can improve the utilization rate of the performance of permanent magnet materials and avoid waste of resources.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A mold for preparing a magnet with surface magnetic concentration function, comprising:

[0006] A mold cavity, including a mold cavity opening and a mold cavity bottom, and the mold cavity opening and the mold cavity bottom are arranged opposite to each other up and down;

[0007] A first alloy block and a second alloy block, both the first alloy block and the second alloy block can move up and down along the opening direction of the cavity opening of the mold cavity. Among them, the cavity opening of the mold cavity is closed or opened by the movement of the first alloy block, and the second alloy block is located at the bottom of the mold cavity, and the demolding of the formed magnet in the mold cavity is realized by the movement of the second alloy block;

[0008] Two orientation coils are arranged in the first alloy block or the second alloy block and are located on the same horizontal plane. Among them, when opposite-direction currents are passed through the two orientation coils, the first magnetic field and the second magnetic field formed by the two orientation coils are respectively distributed in concentric circles, and the magnetic force lines generated by the first magnetic field and the second magnetic field in the area between the two orientation coils repel each other and do not intersect, so that the distance between any two adjacent magnetic force lines on the side close to the orientation coil in the upper and lower sides of the formed magnet is less than the distance between the corresponding two adjacent magnetic force lines on the side far from the orientation coil.

[0009] In the above-mentioned mold for preparing a magnet with surface magnetic concentration function, when the two orientation coils are arranged in the first alloy block and opposite-direction currents are passed through, the density of the magnetic force lines on the side facing the cavity opening of the mold cavity is greater than the density of the magnetic force lines on the side facing the bottom of the mold cavity, so that the surface magnetic force on the side of the formed magnet in the mold cavity close to the cavity opening is greater than the surface magnetic force on the side close to the bottom of the mold cavity.

[0010] In the above-mentioned mold for preparing a magnet with surface magnetic concentration function, the magnetic force lines of the magnetic field formed by the two orientation coils enter the formed magnet from the side far from the orientation coil, leave the formed magnet from the side close to the orientation coil and return to the corresponding orientation coil.

[0011] In the above-mentioned mold for preparing a magnet with surface magnetic concentration function, the magnetic force lines in the magnetic field generated by the orientation coil enter from one side or multiple sides of the formed magnet in an arc curve manner, and leave from one side of the formed magnet and return to the corresponding orientation coil. Among them, the angle between the tangent line on the side where the magnetic force line enters the formed magnet on the arc curve and the vertical plane is greater than the angle between the tangent line on the side where the magnetic force line leaves the formed magnet on the corresponding arc curve and the vertical plane.

[0012] In the above-mentioned mold for preparing a magnet with surface magnetic concentration function, when the two orientation coils are symmetrically distributed along the mold cavity, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil is located in the middle region of the formed magnet; when the two orientation coils are asymmetrically distributed along the mold cavity, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil is close to the side of the two orientation coils far from the mold cavity.

[0013] In the above-mentioned mold with surface magnetic focusing function, when two orientation coils are symmetrically distributed along the mold cavity and are located within the first alloy block, the outermost magnetic force lines of the first magnetic field and the second magnetic field formed by the two orientation coils are tangent to each other to form a tangent point. Among them, the tangent point is located outside the forming magnet, and the vertical symmetry axis of the forming magnet passes through the tangent point.

[0014] In the above-mentioned mold with surface magnetic focusing function, the mold cavity further includes a plurality of mold cavity walls located on the side of the mold cavity. Among them, when two orientation coils are located within the first alloy block along the mold cavity, the magnetic force lines of the magnetic field formed by the two orientation coils enter the forming magnet from the sides opposite to the mold cavity bottom and the mold cavity walls respectively, and leave the forming magnet from the side opposite to the mold cavity opening and then return to the corresponding orientation coils.

[0015] In the above-mentioned mold with surface magnetic focusing function, the pressing direction of the permanent magnetic material in the mold cavity is perpendicular to the demolding direction of the magnet formed after the permanent magnetic material is pressed and formed.

[0016] In the above-mentioned mold with surface magnetic focusing function, the number of the mold cavity walls on the mold cavity is four, and two of the four mold cavity walls that are oppositely arranged are movably arranged as movable mold cavity walls, and the other two oppositely arranged mold cavity walls are fixedly arranged as fixed mold cavity walls. Among them, the side where the movable mold cavity wall is located is the pressing direction of the permanent magnetic material, and the side where the mold cavity opening is located is the demolding direction of the magnet after the permanent magnetic material is formed.

[0017] In the above-mentioned mold with surface magnetic focusing function, the pressing direction of the permanent magnetic material in the mold cavity is parallel to the axis direction of the orientation coil, and the vertical plane where the orientation coil is located is parallel to the vertical plane where the corresponding fixed mold cavity wall is located.

[0018] In the above-mentioned mold with surface magnetic focusing function, the mold further includes a forming template, and the mold cavity is located within the forming template. Among them, the connecting line between the lowest point of the orientation coil and the highest point of the corresponding side wall on the forming template forms an angle α with the vertical plane where the corresponding side wall is located, and the angle α is between 0° and 90°.

[0019] In the above-mentioned mold with surface magnetic focusing function, the angle α is between 30° and 70°.

[0020] In the above-mentioned mold with surface magnetic focusing function, the mold further includes:

[0021] An operation panel, which has an upper surface and a lower surface respectively arranged along the demolding direction of the forming magnet, and the forming template is installed on the upper surface of the operation panel;

[0022] The moving die mechanism is mounted on the upper surface of the forming template or the operation panel through the first bracket, and a first alloy block is connected to the output end of the moving die mechanism. Among them, two orientation coils are arranged side by side in the first alloy block;

[0023] The demolding mechanism is mounted on the lower surface of the operation panel through the second bracket, and a second alloy block is connected to the output end of the demolding mechanism. Among them, when the permanent magnetic material is pressed, the surface of the second alloy block facing the mold cavity is flush with the bottom of the mold cavity. When the magnet is formed, the second alloy block extends into the mold cavity to realize the demolding of the formed magnet;

[0024] The first pressing mechanism and the second pressing mechanism are respectively mounted on the operation panel through the third bracket and the fourth bracket, and are respectively located on both sides of the forming template. Among them, the output ends of the first pressing mechanism and the second pressing mechanism are respectively provided with a first movable part and a second movable part, and the first movable part and the second movable part are respectively two relatively arranged movable mold cavity walls on the mold cavity.

[0025] In the above-mentioned mold for preparing a magnet with surface magnetic focusing function, the first bracket includes a first support plate parallel to the plane where the mold cavity opening is located, and support columns are arranged at each corner of the first support plate. Among them, one end of the support column is connected to the first support plate, the other end of the support column is connected to the upper surface of the forming template or the operation panel, and the power source of the moving die mechanism is installed on the first support plate; or the second bracket is C-shaped, and both sides of the open end of the second bracket are respectively connected to the lower surface of the operation panel. Among them, the power source of the demolding mechanism is connected to the closed end of the second bracket; or two slot holes are arranged on the operation panel along the demolding direction of the formed magnet, the slot holes penetrate the upper surface and the lower surface of the operation panel, and the third bracket and the fourth bracket are respectively located in the two slot holes. Among them, the power sources of the first pressing mechanism and the second pressing mechanism are embedded in the corresponding slot holes.

[0026] The present invention also provides a magnet using the above-mentioned mold, and the magnet is one of a neodymium iron boron permanent magnet, a samarium cobalt permanent magnet, an aluminum nickel cobalt permanent magnet, and a ferrite magnet.

[0027] In the above-mentioned magnet, the preparation method of the magnet successively includes melting, powder making, orientation, forming, sintering and aging. During the orientation process, the fine powder obtained by powder making is put into the mold, and then the pulse power supply is started to turn on the pulse magnetic field orientation. The magnetic force lines of the two electric fields enter the magnet in an arc shape from the side opposite to the bottom of the mold cavity and the side opposite to the fixed mold cavity wall, and leave from the side opposite to the mold cavity opening and return to the corresponding orientation coil. Among them, the magnetic force lines on the surface of the formed magnet on the same side as the mold cavity opening are denser.

[0028] Compared with the prior art, the beneficial effects of the present invention:

[0029] (1). A mold with surface magnetic concentration function provided by the present invention has two orientation coils on the same side of the mold cavity and in the same horizontal plane. When opposite-direction currents are passed through the two orientation coils, two mutually repulsive magnetic fields are formed, making the density of magnetic field lines on the side of the formed magnet in the mold cavity near the cavity opening different from that near the cavity bottom. Among them, the higher the density, the better the magnetic concentration effect and performance, thereby improving the utilization rate of the performance of permanent magnet materials.

[0030] (2). The user can move one or both of the two orientation coils horizontally to change the position of the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil, so as to achieve the corresponding performance of the required formed magnet, and thus improve the flexibility of mold use.

[0031] (3). The pressing direction of the magnet is perpendicular to the demolding direction, and a set of relatively arranged mold cavity walls among the four mold cavity walls are set to be movable. When the formed magnet is demolded, the formed magnet only contacts two fixed mold cavity walls and does not contact the two movable mold cavity walls, changing the contact surface from the original four to two, which is convenient for demolding the formed magnet and reduces the probability of deformation of the formed magnet during demolding, thereby improving the qualified rate of the finished product.

[0032] (4). By deepening the depth of the mold cavity, a "one-out-many" working mode is realized, that is, a larger-sized formed magnet can be formed in one molding, and then the larger-sized formed magnet is cut into formed magnets of the required size by cutting. Thereby improving the forming efficiency of the magnet.

[0033] (5). By changing the angle of the included angle α, the radian of the magnetic field lines when the magnetic field lines generated by the orientation coil enter the formed magnet is realized. When the angle of the included angle α is too large, the radian of the magnetic field lines is synchronously too large, resulting in cracking of the formed magnet during sintering to densification. When the angle of the included angle α is too small, the radian of the magnetic field lines is too gentle, resulting in a small increase in the performance of the product and an inability to form an anisotropic product. Therefore, the angle of the included angle α is preferably between 30° and 70°. Description of the Drawings

[0034] Figure 1 is the schematic diagram of the magnetic field formed after the two orientation coils of the present invention are energized.

[0035] Figure 2 is the structural schematic diagram of a mold with surface magnetic concentration function of the present invention.

[0036] Figure 3 is the partial structural schematic diagram of a mold with surface magnetic concentration function of the present invention.

[0037] Figure 4 It is a partial cross-sectional view of a mold with a surface magnetoconcentration function prepared by the present invention.

[0038] Figure 5 It is a schematic structural diagram of a forming template in a preferred embodiment of the present invention.

[0039] Figure 6 It is a schematic structural diagram of an operation panel in a preferred embodiment of the present invention.

[0040] Figure 7 It is a schematic structural diagram of a guiding structure in a preferred embodiment of the present invention.

[0041] In the figure,

[0042] 100, forming template; 110, mold cavity; 111, mold cavity opening; 112, mold cavity bottom; 113, mold cavity wall;

[0043] 200, operation panel; 210, upper surface; 220, lower surface; 230, slot hole; 240, third bracket; 250, fourth bracket;

[0044] 300, moving die mechanism; 310, first bracket; 311, first support plate; 312, support column; 313, fixing plate; 314, sleeve; 315, guiding rod; 320, first alloy block; 330, orientation coil;

[0045] 400, demoulding mechanism; 410, second bracket; 420, second alloy block;

[0046] 500, first pressing mechanism; 510, first moving part;

[0047] 600, second pressing mechanism; 610, second moving part;

[0048] 700, box body. Detailed implementation manners

[0049] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0050] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0051] As Figures 1 to 7 shown, a mold with a surface magnetoconcentration function provided by the present invention includes:

[0052] The mold cavity 110 is a sunken cavity, including a mold cavity opening 111 and a mold cavity bottom 112, and the mold cavity opening 111 and the mold cavity bottom 112 are arranged opposite to each other vertically.

[0053] The first alloy block 320 and the second alloy block 420, and both the first alloy block 320 and the second alloy block 420 can move up and down along the opening direction of the mold cavity opening 111. Among them, the mold cavity opening 111 is closed or opened by the movement of the first alloy block 320, and the second alloy block 420 is located at the mold cavity bottom 112, and demolding of the formed magnet in the mold cavity 110 is achieved by the movement of the second alloy block 420.

[0054] Two orientation coils 330 are arranged in the first alloy block 320 or the second alloy block 420 and are located on the same horizontal plane. Among them, when opposite-direction currents are passed through the two orientation coils 330, the first magnetic field and the second magnetic field with concentrically distributed magnetic force lines are respectively formed by the two orientation coils 330, and the magnetic force lines generated by the first magnetic field and the second magnetic field repel each other and do not intersect in the area between the two orientation coils 330, so that the distance between any two adjacent magnetic force lines on the side close to the orientation coils 330 in the upper and lower sides of the formed magnet is smaller than the distance between the corresponding adjacent two magnetic force lines on the side far from the orientation coils 330.

[0055] It is worth mentioning that when the two orientation coils 330 are arranged in the first alloy block 320 and opposite-direction currents are passed through, the distance between any two adjacent magnetic force lines on the side facing the mold cavity opening 111 is smaller than the distance between the corresponding adjacent two magnetic force lines on the side facing the mold cavity bottom 112, that is, the density of the magnetic force lines on the side facing the mold cavity opening 111 is greater than the density of the magnetic force lines on the side facing the mold cavity bottom 112, so that the surface magnetic force of the formed magnet in the mold cavity 110 on the side close to the mold cavity opening 111 is greater than the surface magnetic force on the side close to the mold cavity bottom 112; when the two orientation coils 330 are arranged in the second alloy block 420 and opposite-direction currents are passed through, the distance between any two adjacent magnetic force lines on the side facing the mold cavity opening 111 is greater than the distance between the corresponding adjacent two magnetic force lines on the side facing the mold cavity bottom 112, that is, the density of the magnetic force lines on the side facing the mold cavity bottom 112 is greater than the density of the magnetic force lines on the side facing the mold cavity opening 111, so that the surface magnetic force of the formed magnet in the mold cavity 110 on the side close to the mold cavity opening 111 is smaller than the surface magnetic force on the side close to the mold cavity bottom 112.

[0056] It is worth mentioning that the surface magnetic force in the magnet refers to the magnetic field strength or magnetic flux density measured on the surface of the magnet, which describes the magnetic field strength at a certain point on the surface of the magnet.

[0057] The present invention provides a mold with a surface magnetic concentration function. Two orientation coils 330 are on the same side and in the same horizontal plane. When opposite-direction currents are passed through the two orientation coils 330, two mutually repulsive magnetic fields are formed, making the magnetic flux density inconsistent between the side of the formed magnet in the mold cavity 110 near the cavity opening 111 and the side near the cavity bottom 112. Among them, the higher the density, the better the magnetic concentration effect and performance, thereby improving the utilization rate of the performance of the permanent magnetic material.

[0058] It is further pointed out that the magnetic field lines in the magnetic field generated by the orientation coil 330 enter from one side or multiple sides of the formed magnet in the form of an arc curve and leave from one side of the formed magnet and return to the corresponding orientation coil 330. Among them, the radian of the arc curve entering one side of the formed magnet is smaller than the radian of the arc curve leaving one side of the formed magnet. That is, the arc of the arc curve entering one side of the formed magnet is relatively gentle, and the arc of the arc curve leaving one side of the formed magnet is steep.

[0059] It is worth mentioning that the angle between the tangent of the arc curve entering one side of the formed magnet and the vertical plane is greater than the angle between the tangent of the corresponding arc curve leaving one side of the formed magnet and the vertical plane.

[0060] It is further pointed out that the magnetic field lines of the magnetic field formed by the two orientation coils 330 enter the formed magnet from the side far from the orientation coils 330 and leave the formed magnet from the side close to the orientation coils 330 and return to the corresponding orientation coils 330.

[0061] It is worth mentioning that the mold cavity 110 further includes a plurality of mold cavity walls 113 located on the side of the mold cavity 110. Among them, when the two orientation coils 330 are symmetrically distributed along the mold cavity 110 and located in the first alloy block 320, the magnetic field lines of the magnetic field formed by the two orientation coils 330 enter the formed magnet from the sides opposite to the mold cavity bottom 112 and the mold cavity walls 113 respectively, and leave the formed magnet from the side opposite to the mold cavity opening 111 and then return to the corresponding orientation coils 330; when the two orientation coils 330 are symmetrically distributed along the mold cavity 110 and located in the second alloy block 420, the magnetic field lines of the magnetic field formed by the two orientation coils 330 enter the formed magnet from the sides corresponding to the mold cavity opening 111 and the mold cavity walls 113 respectively, and leave the formed magnet from the side opposite to the mold cavity bottom 112 and then return to the corresponding orientation coils 330.

[0062] It is further pointed out that when the two orientation coils 330 are symmetrically distributed along the mold cavity 110 and located in the first alloy block 320, the outermost magnetic field lines of the first magnetic field and the second magnetic field formed by the two orientation coils 330 are tangent to each other to form a tangent point. Among them, the tangent point is outside the formed magnet, and the vertical symmetry axis of the formed magnet passes through the tangent point.

[0063] It is further pointed out that when one or both of the two orientation coils 330 move horizontally, such that the horizontal distances between the two orientation coils 330 and the mold cavity 110 are unequal respectively, the region with the strongest surface magnetic force on the formed magnet on the side facing the orientation coil 330 will shift.

[0064] It is worth mentioning that when the two orientation coils 330 are symmetrically distributed along the mold cavity 110, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil 330 is located in the middle region of the formed magnet; when the two orientation coils 330 are asymmetrically distributed along the mold cavity 110, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil 330 is close to the side of the two orientation coils 330 that is far from the mold cavity 110.

[0065] In this embodiment, the user can move one or both of the two orientation coils 330 horizontally, thereby changing the position of the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coil 330, so as to achieve the corresponding performance of the required formed magnet, and further improve the flexibility of mold use.

[0066] Preferably, the pressing direction of the permanent magnetic material in the mold cavity 110 is perpendicular to the demolding direction of the magnet formed after the permanent magnetic material is pressed and formed.

[0067] It is further pointed out that the number of the mold cavity walls 113 on the mold cavity 110 is four, and two of the four mold cavity walls 113 that are oppositely arranged are movably arranged, serving as movable mold cavity walls, and the other two oppositely arranged mold cavity walls 113 are fixedly arranged, serving as fixed mold cavity walls. Among them, the side where the movable mold cavity wall is located is the pressing direction of the permanent magnetic material, and the side where the mold cavity opening 111 is located is the demolding direction of the magnet after the permanent magnetic material is formed.

[0068] It is worth mentioning that in the prior art, the pressing direction and the demolding direction of the formed magnet are the same, and all four mold cavity walls 113 of the mold cavity 110 are fixed mold cavity walls, resulting in that each side of the formed magnet contacts the corresponding fixed mold cavity wall during demolding, that is, the contact surface between the formed magnet and the fixed mold cavity wall is four. On the one hand, it increases the demolding difficulty of the formed magnet, and on the other hand, due to the large number of contact surfaces and the thin thickness of the formed magnet, the formed magnet is prone to deformation during demolding, corresponding to the final qualified rate of the product.

[0069] In this embodiment, the pressing direction of the magnet is perpendicular to the demolding direction, and a set of relatively arranged cavity walls 113 among the four cavity walls 113 are set to be movable. When the formed magnet is demolded, the formed magnet only contacts two fixed cavity walls and does not contact the two movable cavity walls, reducing the contact surfaces from the original four to two. This facilitates the demolding of the formed magnet, reduces the probability of deformation of the formed magnet during demolding, and thus improves the qualified rate of the finished product.

[0070] It is further pointed out that in the prior art, since the pressing direction of the formed magnet is the same as the demolding direction, in order to control the deformation amount of the formed magnet during demolding, a "one-out-one" working mode is generally adopted, that is, only one formed magnet is formed at a time. In this embodiment, since the pressing direction of the formed magnet is perpendicular to the demolding direction, the "one-out-many" working mode can be realized by deepening the depth of the cavity 110, that is, a formed magnet with a larger size can be formed at a time, and then the formed magnet with a larger size can be cut into formed magnets with the required sizes by cutting. This improves the forming efficiency of the magnet.

[0071] Further preferably, the pressing direction of the permanent magnetic material in the cavity 110 is parallel to the axis direction of the orientation coil 330, and the vertical plane where the orientation coil 330 is located is parallel to the vertical plane where the corresponding fixed cavity wall is located.

[0072] Preferably, the mold further includes a forming template 100, and the cavity 110 is located in the forming template 100. Among them, the included angle α is formed between the connection line between the lowest point of the orientation coil 330 and the highest point of the corresponding side wall on the forming template 100 and the vertical plane where the corresponding side wall is located, and the angle of the included angle α is between 0° and 90°.

[0073] It is further pointed out that when the two orientation coils 330 approach each other, the angle of the included angle α gradually decreases; when the two orientation coils 330 move away from each other, the angle of the included angle α gradually increases; when the two orientation coils 330 approach each other and the vertical plane where the axis of the orientation coil 330 is located is collinear with the vertical plane where the corresponding side wall on the forming template 100 is located, the angle of the included angle α is 0°; when the two orientation coils 330 move away from each other and are far enough apart, the angle of the included angle α approaches 90° infinitely.

[0074] In this embodiment, by changing the angle of the included angle α, the magnetic line radian when the magnetic lines of the magnetic field generated by the orientation coil 330 enter the formed magnet is achieved. When the angle of the included angle α is too large, the magnetic line radian is synchronously too large, which may cause cracking of the formed magnet during sintering to densification. When the angle of the included angle α is too small, the magnetic line radian is too gentle, resulting in a small improvement in product performance and an inability to form an anisotropic product.

[0075] It is further pointed out that the angle of the included angle α is preferably between 30° and 70°.

[0076] Preferably, the mold further includes:

[0077] An operation panel 200, with an upper surface 210 and a lower surface 220 respectively arranged along the demolding direction of the formed magnet, and the forming template 100 is installed on the upper surface 210 of the operation panel 200;

[0078] A moving die mechanism 300, which is installed on the upper surface 210 of the forming template 100 or the operation panel 200 through a first bracket 310, and the output end of the moving die mechanism 300 is connected with a first alloy block 320. Among them, two orientation coils 330 are arranged side by side in the first alloy block 320;

[0079] A demolding mechanism 400, which is installed on the lower surface 220 of the operation panel 200 through a second bracket 410, and the output end of the demolding mechanism 400 is connected with a second alloy block 420. Among them, when the permanent magnetic material is pressed, the surface of the second alloy block 420 facing the mold cavity 110 is flush with the bottom 112 of the mold cavity. When the magnet is formed, the second alloy block 420 extends into the mold cavity 110 to realize demolding of the formed magnet;

[0080] A first pressing mechanism 500 and a second pressing mechanism 600, which are respectively installed on the operation panel 200 through a third bracket 240 and a fourth bracket 250, and are respectively located on both sides of the forming template 100. Among them, the output ends of the first pressing mechanism 500 and the second pressing mechanism 600 are respectively provided with a first movable part 510 and a second movable part 610, and the first movable part 510 and the second movable part 610 are respectively two relatively arranged movable mold cavity walls on the mold cavity 110.

[0081] It is worth mentioning the forming principle of the formed magnet: In the initial state, the first movable parts 510 of the first pressing mechanism 500 and the second movable parts 610 of the second pressing mechanism 600 respectively seal the left and right sides of the cavity 110 as the cavity walls of the movable cavity. The side of the second alloy block 420 facing the cavity 110 at the output end of the demoulding mechanism 400 is flush with the plane where the cavity bottom 112 is located, so that the bottom and side parts of the whole cavity 110 are in a closed state. At this time, the permanent magnetic material is filled into the cavity 110 and fills the whole cavity 110; then the moving die mechanism 300 drives the first alloy block 320 to move in the direction close to the cavity 110 and closes the cavity opening 111; then the pulse power supply is started to turn on the pulse magnetic field orientation, the number of pulse orientations is 3-6 times, and the pulse magnetic field is not less than 1T, so that there is a difference in the surface magnetic force on the side of the permanent magnetic material in the cavity 110 facing the cavity opening 111 and the side facing the cavity bottom 112, that is, the surface magnetic force on the side of the permanent magnetic material facing the cavity opening 111 is greater than the surface magnetic force on the side facing the cavity bottom 112; then the first pressing mechanism 500 and the second pressing mechanism 600 respectively drive the first movable part 510 and the second movable part 610 to move towards each other to press the permanent magnetic material to form a magnet. Among them, the density of the formed magnet is controlled at 3.8-4.5g / cm 3 , the pressure is not less than 5 tons, preferably 8-15 tons (since the size of the product is too small, too much pressure is likely to crush the formed magnet); finally, after the pressing is completed, the first pressing mechanism 500 and the second pressing mechanism 600 respectively drive the first movable part 510 and the second movable part 610 to move in the direction away from the cavity 110 again, open the movable cavity walls of the cavity 110, and drive the second alloy block 420 to move towards the cavity opening 111 through the demoulding mechanism 400 to realize the demoulding of the formed magnet.

[0082] Furthermore, it is worth mentioning that the power sources of the moving die mechanism 300, the demoulding mechanism 400, the first pressing mechanism 500 and the second pressing mechanism 600 can be cylinders or oil cylinders or linear motors, but are not limited to cylinders or oil cylinders or linear motors.

[0083] Preferably, the first bracket 310 includes a first support plate 311 parallel to the plane where the cavity opening 111 is located, and support columns 312 are arranged at each corner of the first support plate 311. One end of the support column 312 is connected to the first support plate 311, the other end of the support column 312 is connected to the upper surface 210 of the forming template 100 or the operation panel 200, and the power source of the moving die mechanism 300 is installed on the first support plate 311.

[0084] Further preferably, a guiding structure is further provided between the power source of the moving die mechanism 300 and the first alloy block 320, and the guiding structure includes a fixing plate 313 clamped between the first support plate 311 and the power source of the moving die mechanism 300. Wherein, a sleeve 314 is provided on the fixing plate 313, and a guiding rod 315 connected to the first alloy block 320 is nested in the sleeve 314.

[0085] Preferably, the second bracket 410 is arranged in a C shape, and both sides of the open end of the second bracket 410 are respectively connected to the lower surface 220 of the operation panel 200. Wherein, the power source of the demolding mechanism 400 is connected to the closed end of the second bracket 410.

[0086] Preferably, two slot holes 230 are arranged on the operation panel 200 along the demolding direction of the forming magnet. The slot holes 230 penetrate through the upper surface 210 and the lower surface 220 of the operation panel 200, and the third bracket 240 and the fourth bracket 250 are respectively located in the two slot holes 230. Wherein, the power sources of the first pressing mechanism 500 and the second pressing mechanism 600 are embedded in the corresponding slot holes 230.

[0087] Preferably, the mold further includes a box body 700, and the operation panel 200 is installed on the box body 700. Wherein, the forming template 100 and the moving die mechanism 300 are located outside the box body 700, the demolding mechanism 400 is located inside the box body 700, and a part of the structures of the first pressing mechanism 500 and the second pressing mechanism 600 are located outside the box body 700, and another part of the structures are located inside the box body 700.

[0088] The present invention also provides a magnet, and the magnet can be a neodymium iron boron permanent magnet, a samarium cobalt permanent magnet, an alnico permanent magnet, or a ferrite magnet.

[0089] It is further pointed out that the neodymium iron boron permanent magnet is a permanent magnetic material made of an alloy based on neodymium, iron, and boron, and the grades include N series (such as N30, N33, N35, N38, N40, N42, N45, N48, N50, N52, etc.), M series (such as M28, M35, M38, M45, M50, M55, M60, M70, M80, etc.), H series (such as 35H, 38H, 45H, 48H, etc.), SH series (42SH), UH series (35UH, etc.), EH series, etc.

[0090] The samarium cobalt permanent magnet is a permanent magnetic material made of an alloy based on samarium and cobalt, mainly including 1:5 type and 2:17 type.

[0091] Alnico permanent magnets are mainly composed of aluminum, nickel, cobalt, and iron elements. In addition, other alloy elements can be included, and other alloy elements can be listed as copper, titanium, zirconium, silicon, manganese, etc. The grades include AlNiCo1, AlNiCo2, AlNiCo3, AlNiCo4, AlNiCo5, AlNiCo6, AlNiCo7, AlNiCo8, AlNiCo9, etc.

[0092] Ferrite magnets are a composite material based on iron oxides and other metal oxides. Other metal oxides can be listed as barium oxide, strontium oxide, cobalt oxide, manganese oxide, nickel oxide, zinc oxide, magnesium oxide, etc. The grades mainly include Y10T, Y20, Y25, Y30, Y30BH, Y33, Y35, etc.

[0093] The present invention also provides a method for preparing a magnet, which sequentially includes the following steps: melting, powder making, orientation, forming, sintering, and aging; during orientation, first put the fine powder obtained from powder making into a mold, and then start a pulse power supply to turn on a pulsed magnetic field for orientation. The number of pulsed orientations is 3 - 6 times, and the pulsed magnetic field is not less than 1T. The magnetic field lines of the two electric fields enter the magnet in an arc from the side opposite to the bottom 112 of the mold cavity and the side opposite to the fixed mold cavity wall, and leave from the side opposite to the mold cavity opening 111 and return to the corresponding orientation coil 330. Among them, the magnetic field lines on the surface of the formed magnet on the same side as the mold cavity opening 111 are denser, thereby improving the performance of this side surface.

[0094] Further regarding the melting, powder making, orientation, forming, sintering solution and aging treatment steps involved in the preparation method, of course, these descriptions are only exemplary, and the disclosure of the present invention is not limited thereto.

[0095] Melting step: Put raw materials such as PrNd (rare earth elements), BFe (ferroboron), pure Fe, and doping elements pure Cu, Al, Ga, Zr, etc. into a melting furnace for melting, and then cast to obtain alloy cast sheets or alloy ingots; weigh each raw material according to the magnet grade formula (different grades have different raw material ratios) for batching, put the raw materials into a vacuum melting furnace, evacuate the vacuum in the furnace to <1×10 -1 Pa, fill with an inert gas, and heat up to 1400 - 1700 °C for melting, keep warm for 5 - 30 min. After melting, pour the high-temperature alloy solution for casting and spinning to obtain alloy cast sheets, or pour the high-temperature alloy solution into a water-cooled copper mold and cool to form alloy ingots.

[0096] Powder making step: Coarse crush the alloy cast sheets or alloy ingots to obtain coarse powder, and then perform fine crushing to obtain fine powder; Coarse crushing can be listed as hydrogen crushing, and fine crushing can be listed as jet mill crushing.

[0097] Hydrogen Crushing: Place the alloy cast sheet or alloy ingot in a hydrogen crushing furnace. Evacuate the hydrogen crushing furnace to < 1×10 -1 Pa at room temperature, and then introduce hydrogen with a purity of 99.9% into the hydrogen crushing furnace. Under the hydrogen absorption temperature and hydrogen absorption pressure, allow the alloy to fully absorb hydrogen; then, while evacuating, raise the temperature to the dehydrogenation temperature to allow the alloy to fully dehydrogenate; afterwards, perform a cooling treatment to obtain coarse powder with a particle size range of 10 - 700 μm. The hydrogen absorption temperature can be exemplified as 20 - 300 °C. The hydrogen absorption pressure can be exemplified as 50 - 600 kPa. The dehydrogenation temperature can be exemplified as 400 - 700 °C, and more preferably 500 - 600 °C.

[0098] Jet Mill Crushing: Place the coarse powder in a jet mill and perform jet milling under an inert gas at a pressure of 0.1 - 2 MPa to obtain fine powder with an average particle size of 2 - 5 μm.

[0099] Sintering Step: The green compact after orientation pressing is subjected to vacuum sintering. The vacuum degree ≤ 1*10-1 Pa, the sintering temperature is 1000 - 1100 °C, and the sintering time is 2 - 8 h;

[0100] Aging Treatment Step: The sintered magnet is subjected to aging treatment in a vacuum environment at a temperature of 300 - 600 °C for a treatment time of 1 - 5 h, or it can also be a two-stage aging treatment. First, treat at 600 - 1000 °C for 1 - 3 h, and then cool down to 400 - 600 °C for 1 - 5 h.

[0101] In this embodiment, the sintered magnet is subjected to magnetization treatment after grinding. A typical magnetic concentrating surface is formed on the surface of the product on the side that originally faced the orientation coil 330 after magnetization.

[0102] It should be noted that in the present invention, descriptions such as "first", "second", "one", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. Terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0103] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0104] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A mold for preparing a magnet with surface poly-magnetic function, characterized in that, Comprising: A mold cavity, including a mold cavity opening and a mold cavity bottom, and the mold cavity opening and the mold cavity bottom are arranged opposite to each other vertically; A first alloy block and a second alloy block, and both the first alloy block and the second alloy block can move up and down along the opening direction of the mold cavity opening. Among them, the mold cavity opening is closed or opened by the movement of the first alloy block, the second alloy block is located at the mold cavity bottom, and the demolding of the formed magnet in the mold cavity is realized by the movement of the second alloy block; Two orientation coils, arranged in the first alloy block or the second alloy block and located on the same horizontal plane. Among them, when opposite-direction currents are passed through the two orientation coils, the first magnetic field and the second magnetic field with magnetic force lines distributed in concentric circles are respectively formed by the two orientation coils, and the magnetic force lines generated by the first magnetic field and the second magnetic field repel each other and do not intersect in the area between the two orientation coils, so that the distance between any two adjacent magnetic force lines on the side close to the orientation coils in the upper and lower sides of the formed magnet is smaller than the distance between the corresponding two adjacent magnetic force lines on the side far from the orientation coils; When the two orientation coils are arranged in the first alloy block and opposite-direction currents are passed through them, the density of the magnetic force lines on the side facing the mold cavity opening is greater than the density of the magnetic force lines on the side facing the mold cavity bottom, so that the surface magnetic force on the side of the formed magnet in the mold cavity close to the mold cavity opening is greater than the surface magnetic force on the side close to the mold cavity bottom.

2. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 1, characterized in that, The magnetic force lines of the magnetic fields formed by the two orientation coils enter the formed magnet from the side far from the orientation coils, leave the formed magnet from the side close to the orientation coils and return to the corresponding orientation coils.

3. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 2, characterized in that The magnetic force lines in the magnetic field generated by the orientation coil enter the formed magnet from one side or multiple sides of the formed magnet in an arc-shaped curve manner, and leave the formed magnet from one side of the formed magnet and return to the corresponding orientation coil. Among them, the angle between the tangent line on the side where the arc-shaped curve enters the formed magnet and the vertical plane is greater than the angle between the tangent line on the side where the arc-shaped curve leaves the formed magnet and the vertical plane.

4. The mold for preparing a magnet with a surface poly-magnetic function according to claim 1, characterized in that, When the two orientation coils are symmetrically distributed along the mold cavity, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coils is located in the middle region of the formed magnet; when the two orientation coils are asymmetrically distributed along the mold cavity, the region with the strongest surface magnetic force on the side of the formed magnet facing the orientation coils is close to the side of the two orientation coils far from the mold cavity.

5. The mold for preparing a magnet with a surface poly-magnetic function according to claim 4, characterized in that, When the two orientation coils are symmetrically distributed along the mold cavity and are located in the first alloy block, the outermost magnetic force lines of the first magnetic field and the second magnetic field formed by the two orientation coils are tangent to each other to form a tangent point. Among them, the tangent point is located outside the formed magnet, and the vertical symmetry axis of the formed magnet passes through the tangent point.

6. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 3, characterized in that, The mold cavity further includes a plurality of mold cavity walls, located on the side of the mold cavity. Among them, when the two orientation coils are located in the first alloy block along the mold cavity, the magnetic force lines of the magnetic fields formed by the two orientation coils enter the formed magnet from the sides opposite to the mold cavity bottom and the mold cavity walls respectively, and leave the formed magnet from the side opposite to the mold cavity opening and then return to the corresponding orientation coils.

7. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 6, characterized in that, The pressing direction of the permanent magnet material in the mold cavity is perpendicular to the demolding direction of the magnet formed after the permanent magnet material is pressed and formed.

8. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 7, characterized in that, The number of cavity walls on the mold cavity is four, and two of the four cavity walls, which are oppositely arranged, are movably arranged and are movable cavity walls, while the other two oppositely arranged cavity walls are fixedly arranged and are fixed cavity walls. Among them, the side where the movable cavity wall is located is the pressing direction of the permanent magnet material, and the side where the mold cavity opening is located is the demolding direction of the magnet after the permanent magnet material is formed.

9. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 8, characterized in that, The pressing direction of the permanent magnet material in the mold cavity is parallel to the axial direction of the orientation coil, and the vertical plane where the orientation coil is located is parallel to the vertical plane where the corresponding fixed cavity wall is located.

10. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 1, characterized in that, The mold further includes a forming template, and the mold cavity is located within the forming template. Among them, the angle α is formed between the connecting line between the lowest point of the orientation coil and the highest point of the corresponding side wall on the forming template and the vertical plane where the corresponding side wall is located, and the angle α is between 0° and 90°.

11. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 10, characterized in that, The angle α is between 30° and 70°.

12. The mold for preparing a magnet with a surface magnetic aggregation function according to claim 8, characterized in that, The mold further includes: An operation panel, which has an upper surface and a lower surface respectively arranged along the demolding direction of the formed magnet, and the forming template is installed on the upper surface of the operation panel; A moving mold mechanism, which is installed on the upper surface of the forming template or the operation panel through a first bracket, and the output end of the moving mold mechanism is connected with a first alloy block. Among them, two orientation coils are arranged side by side within the first alloy block; A demolding mechanism, which is installed on the lower surface of the operation panel through a second bracket, and the output end of the demolding mechanism is connected with a second alloy block. Among them, when the permanent magnet material is pressed, the surface of the second alloy block facing the mold cavity is flush with the bottom of the mold cavity. When the magnet is formed, the second alloy block extends into the mold cavity to realize the demolding of the formed magnet; A first pressing mechanism, which is installed on the operation panel through a third bracket, and a second pressing mechanism is installed on the operation panel through a fourth bracket. The first pressing mechanism and the second pressing mechanism are respectively located on both sides of the forming template. Among them, the output end of the first pressing mechanism is provided with a first movable part, and the output end of the second pressing mechanism is provided with a second movable part, and the first movable part and the second movable part are respectively two oppositely arranged movable cavity walls on the mold cavity.

13. The mold for preparing a magnet with a surface magnet aggregation function according to claim 12, characterized in that, The first bracket includes a first support plate parallel to the plane where the mold cavity opening is located, and support columns are arranged at each corner of the first support plate. Among them, one end of the support column is connected to the first support plate, the other end of the support column is connected to the upper surface of the forming template or the operation panel, and the power source of the moving mold mechanism is installed on the first support plate; or the second bracket is in a C shape, and both sides of the open end of the second bracket are respectively connected to the lower surface of the operation panel. Among them, the power source of the demolding mechanism is connected to the closed end of the second bracket; or two slot holes are arranged on the operation panel along the demolding direction of the formed magnet, and the slot holes penetrate through the upper surface and the lower surface of the operation panel, and the third bracket and the fourth bracket are respectively located within the two slot holes. Among them, the power sources of the first pressing mechanism and the second pressing mechanism are embedded within the corresponding slot holes.

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