Magnetic ring hot extrusion forming device

Abstract

The utility model provides a hot extrusion forming device for a magnetic ring. The hot extrusion forming device for the magnetic ring comprises a die sleeve, the first pressing head and the second pressing head are movably arranged on the two sides of the green body in the extending direction of the cavity correspondingly, and the first pressing head and the second pressing head can provide opposite acting force for the green body correspondingly; the first extrusion part and the second extrusion part are movably arranged in the cavity in the extending direction of the cavity, and the first pressing head, the second pressing head, the first extrusion part, the second extrusion part and the inner side wall of the die sleeve are matched to form an extrusion cavity so as to carry out extrusion forming on a green body. According to the technical scheme provided by the utility model, the problems that the orientation degree and the magnetic performance of the obtained magnetic ring are not uniform and the produced magnetic ring is relatively low in performance due to the fact that the magnetic ring hot extrusion forming device in the prior art is generally in reverse extrusion when extruding a green body, and the magnetic ring is generally in gradient distribution which is gradually reduced along the extrusion direction can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to hot extrusion forming technical field, specifically, relate to a kind of magnetic ring hot extrusion forming device. BACKGROUND

[0002] Hot pressing / thermal deformation technology is widely used in the preparation of ceramic materials, bulk amorphous materials, composite materials, etc., in the late 1980s, this technology is widely used in magnetic materials. The preparation method of rare earth radiation permanent magnet ring is mostly in the form of magnetic tile splicing ring, but this way has high assembly difficulty, low splicing size precision, and the splicing seam has magnetic leakage phenomenon, and the sintered radiation oriented magnetic ring has the problems of low orientation and easy cracking, and the hot pressing / thermal deformation technology can solve this problem.

[0003] Hot pressing / thermal deformation neodymium-iron-boron magnet is a high-performance magnet with nanocrystalline structure and self-orientation anisotropy, and hot extrusion radiation permanent magnet ring is a kind of thermal deformation magnet. The neodymium-iron-boron grains are preferentially oriented along the c-axis parallel to the pressure direction under the action of low-melting-point rich-neodymium phase and axial pressure to obtain better anisotropy. Hot extrusion magnetic ring has the advantages of high magnetism and less processing. However, in the prior art, the magnetic ring is usually extruded in the opposite direction during processing, so the bottom of the magnetic ring is subjected to the maximum stress, has higher density, the grains are arranged in order, and the orientation degree is the highest. However, the orientation degree and magnetic properties of the magnetic ring gradually decrease from the bottom to the top, resulting in uneven density and magnetic properties of the longitudinal part of the magnetic ring, and low overall performance of the product. SUMMARY

[0004] The utility model provides a kind of magnetic ring hot extrusion forming device to solve the problem that the orientation degree and magnetic properties of the magnetic ring obtained by the magnetic ring hot extrusion forming device in the prior art are uneven when extruding blank, which usually presents a gradient distribution gradually decreasing along the extrusion direction, resulting in low performance of the produced magnetic ring.

[0005] The utility model provides a kind of magnetic ring hot extrusion forming device, and the magnetic ring hot extrusion forming device includes: a die sleeve having a cavity capable of holding a blank, a first and a second pressure head movably arranged on both sides of the blank along the extension direction of the cavity, the first and the second pressure head capable of providing a force in opposite directions to the blank, and the first and the second pressure head drivenly connected to a hot press, a first and a second extrusion member movably arranged in the cavity along the extension direction of the cavity, the first and the second extrusion member correspondingly arranged with the first and the second pressure head, the first extrusion member sleeved on the outer periphery of the first pressure head in the circumferential direction, and the second extrusion member sleeved on the outer periphery of the second pressure head in the circumferential direction, the first and the second pressure head, the first and the second extrusion member, and the inner side wall of the die sleeve cooperating to form an extrusion cavity for extruding and forming the blank, and the first and the second extrusion member drivenly connected to the hot press.

[0006] Further, the magnetic ring hot extrusion forming device further comprises: a first guide structure arranged between the first extrusion member and the die sleeve, the extension direction of the first guide structure being the same as the extension direction of the cavity, the first guide structure being used for guiding the moving direction of the first extrusion member; and a second guide structure arranged between the second extrusion member and the die sleeve, the extension direction of the second guide structure being the same as the extension direction of the cavity, the second guide structure being used for guiding the moving direction of the second extrusion member.

[0007] Further, the first guide structure comprises: a first guide groove arranged on one of the first extrusion member and the die sleeve, the first guide groove extending along the moving direction of the first extrusion member; and a first guide part arranged on the other of the first extrusion member and the die sleeve, at least part of the first guide part being located in the first guide groove and guidingly matched with the first guide groove.

[0008] Further, the second guide structure comprises: a second guide groove arranged on one of the second extrusion member and the die sleeve, the second guide groove extending along the moving direction of the second extrusion member; and a second guide part arranged on the other of the second extrusion member and the die sleeve, at least part of the second guide part being located in the second guide groove and guidingly matched with the second guide groove.

[0009] Further, the magnetic ring hot extrusion forming device further comprises: a plug-in groove arranged on the end face of the first pressing head close to the blank; and a plug-in head arranged on the end face of the second pressing head close to the blank, the plug-in head being arranged correspondingly to the plug-in groove, and the plug-in head being capable of being plugged into the plug-in groove through the blank.

[0010] Further, the cross-sectional area of the plug-in head along the radial direction gradually decreases towards the direction close to the blank.

[0011] Further, the diameter of the first pressing head is greater than or smaller than the diameter of the second pressing head.

[0012] Further, the end of the second pressing head away from the blank has a necked section.

[0013] Further, the edge of the end face of the first pressing head and / or the second pressing head is a circular arc transition.

[0014] Further, the end face of the first pressing head and / or the second pressing head close to the blank is a plane.

[0015] The technical scheme is applied, and the blank body extends between the pressure head and the inner side wall of the die sleeve under the action force of the first pressure head and the second pressure head; the first extrusion piece and the second extrusion piece are driven to move towards the blank body; at this time, the first pressure head, the second pressure head, the first extrusion piece, the second extrusion piece and the inner side wall of the die sleeve cooperatively form an extrusion cavity, and the blank body is extruded and formed. In this way, the first pressure head, the second pressure head, the first extrusion piece and the second extrusion piece can simultaneously and respectively extrude the blank body by the driving of the hot press, so that the stress of the blank body in the extension direction of the extrusion cavity is increased, the uniformity of the stress of the blank body at different positions is improved, the case that the orientation degree and the magnetic property of the product gradually decrease in the extrusion direction due to the uneven stress of the product at two ends is avoided, the compactness of the product at different positions in the extrusion direction is more uniform after the blank body is extruded, the grain arrangement is more uniform, and the orientation degree, the anisotropy and the comprehensive magnetic property of the product are improved. Moreover, the above-mentioned arrangement can also realize forward extrusion, reverse extrusion or simultaneous forward and reverse extrusion of the blank body, and the practicability of the device is improved. Meanwhile, the first pressure head, the second pressure head, the first extrusion piece and the second extrusion piece are respectively driven, so that the shape of the extrusion cavity can be changed, different specifications of products can be obtained according to different requirements, and the flexibility and applicability of the device are improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application, serve to explain the present application. In the drawings:

[0017] Figure 1 A structure schematic view when extrusion starts is shown;

[0018] Figure 2 A structure schematic view when extrusion is completed is shown;

[0019] Figure 3 A structure schematic view when extrusion starts is shown;

[0020] Figure 4 A structure schematic view when extrusion is completed is shown;

[0021] Figure 5 A structure schematic view of a sampling position for testing the magnetic property of a magnetic ring is shown.

[0022] In the above drawings, the following reference signs are used:

[0023] 10, die sleeve; 101, cavity; 102, extrusion cavity;

[0024] 20, first pressing head; 30, second pressing head; 31, necked-down section;

[0025] 40, first extrusion; 50, second extrusion;

[0026] 61, first guide portion; 71, second guide portion;

[0027] 81, insertion slot; 91, insertion head;

[0028] 01, blank; 02, top position; 03, middle position; 04, bottom position. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but by no means as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of the present application.

[0030] As Figure 1 and Figure 2As shown, the utility model embodiment one provides a kind of magnetic ring hot extrusion forming device, which includes: die sleeve 10, first pressure head 20, second pressure head 30, first extruding piece 40 and second extruding piece 50.Wherein, die sleeve 10 has cavity 101, cavity 101 can place blank 01.First pressure head 20 and second pressure head 30 are movably arranged in the extension direction of cavity 101 at the two sides of blank 01 respectively, and first pressure head 20 and second pressure head 30 can provide direction opposite force for blank 01 respectively, and first pressure head 20 and second pressure head 30 are drivenly connected with hot press, specifically, first pressure head 20 and second pressure head 30 can be driven by motor or hydraulic cylinder on hot press.First extruding piece 40 and second extruding piece 50 are movably arranged in cavity 101 along the extension direction of cavity 101 respectively, and first extruding piece 40 and second extruding piece 50 are correspondingly arranged with first pressure head 20 and second pressure head 30 respectively, first extruding piece 40 is sleeved on the outer periphery of first pressure head 20 along the circumferential direction, and second extruding piece 50 is sleeved on the outer periphery of second pressure head 30 along the circumferential direction, and the inner side wall of die sleeve 10 cooperates with first pressure head 20, second pressure head 30, first extruding piece 40, second extruding piece 50 to form extrusion cavity 102, to extrude and form blank 01, extrusion cavity 102 is located in cavity 101, and first extruding piece 40 and second extruding piece 50 are drivenly connected with hot press.Specifically, first extruding piece 40 and second extruding piece 50 can be driven by motor on hot press.

[0031] Wherein, blank 01 is specifically neodymium iron boron material, and the product formed by magnetic ring hot extrusion forming device is neodymium iron boron magnetic ring.

[0032] Specifically, die sleeve 10 needs to bear the extrusion force of blank 01, and needs to be used in high temperature environment, so die sleeve 10 adopts high-temperature alloy material.The material of first pressure head 20, second pressure head 30, first extruding piece 40 and second extruding piece 50 is same, and is high-speed steel or hard alloy material with wear resistance, high strength and high hardness.

[0033] The technical scheme is applied, the blank 01 extends between the pressure head and the inner side wall of the die sleeve 10 under the force of the first pressure head 20 and the second pressure head 30, the first extruding piece 40 and the second extruding piece 50 are driven to move towards the blank 01, at this time, the first pressure head 20, the second pressure head 30, the first extruding piece 40, the second extruding piece 50 and the inner side wall of the die sleeve 10 cooperate to form an extrusion cavity 102, and the blank 01 is extruded and formed. In this way, the first pressure head 20, the second pressure head 30, the first extruding piece 40 and the second extruding piece 50 can simultaneously and respectively extrude the blank 01 by the driving of the hot press, so that the stress of the blank 01 along the extension direction of the extrusion cavity 102 can be increased, the uniformity of the stress of the blank 01 at different positions can be improved, the case that the orientation degree and the magnetic property of the product gradually decrease along the extrusion direction due to the uneven stress of the two ends of the product can be avoided, the density of the product obtained after the blank 01 is extruded is more uniform at different positions along the extrusion direction, the grain arrangement is more orderly, and then the orientation degree, the anisotropy and the comprehensive magnetic property of the product are improved. And the above-mentioned setting can also realize forward extrusion, reverse extrusion or simultaneous forward and reverse extrusion of the blank 01, and the practicability of the device is improved. At the same time, the first pressure head 20, the second pressure head 30, the first extruding piece 40 or the second extruding piece 50 are respectively driven, and the shape of the extrusion cavity 102 can be changed, so that different specifications of products can be obtained according to different requirements, and the flexibility and applicability of the device are improved.

[0034] Preferably, the first extruding piece 40 and the second extruding piece 50 are arranged in parallel with the blank 01, so that the uniformity and consistency of extrusion at different positions of the blank 01 can be increased.

[0035] In the present application, the extension direction of the cavity 101 and the specific side of the blank 01 where the first pressure head 20 and the second pressure head 30 are arranged are not limited. In the present embodiment, the extension direction of the cavity 101 extends along the vertical direction, the first pressure head 20 and the second pressure head 30 move along the vertical direction, the first pressure head 20 is arranged above the blank 01, and the second pressure head 30 is arranged below the blank 01.

[0036] The magnetic ring hot extrusion forming device further comprises a first guide structure and a second guide structure. The first guide structure is arranged between the first extrusion member 40 and the die sleeve 10, the extension direction of the first guide structure is the same as the extension direction of the cavity 101, and the first guide structure is used for guiding the movement direction of the first extrusion member 40. The second guide structure is arranged between the second extrusion member 50 and the die sleeve 10, the extension direction of the second guide structure is the same as the extension direction of the cavity 101, and the second guide structure is used for guiding the movement direction of the second extrusion member 50. The arrangement of the guide structure can make the first extrusion member 40 and the second extrusion member 50 keep stable movement tracks during the extrusion process, ensure the accurate movement of the first extrusion member 40 and the second extrusion member 50 during the extrusion process, avoid the possible deviation of the extrusion member in the high-temperature and high-pressure environment, and improve the controllability of the extrusion process and the size precision of the product.

[0037] As shown in Figure 1 and Figure 2 , the first guide structure comprises a first guide groove and a first guide portion 61. The first guide groove is arranged on one of the first extrusion member 40 and the die sleeve 10, and extends along the movement direction of the first extrusion member 40. The first guide portion 61 is arranged on the other one of the first extrusion member 40 and the die sleeve 10, at least part of the first guide portion 61 is located in the first guide groove, and the first guide portion 61 is guided and matched with the first guide groove. In this way, the first guide portion 61 can move in the first guide groove, ensuring that the movement direction of the first extrusion member 40 is consistent with the extension direction of the cavity 101, realizing the stable guidance of the first extrusion member 40 during the extrusion process, avoiding the uneven extrusion of the blank 01 due to the deviation of the position of the first extrusion member 40 during the extrusion of the blank 01, and improving the stability and consistency of the performance of the magnetic ring. At the same time, the first guide structure is arranged as the mutual cooperation of the first guide groove and the first guide portion 61, which is simple in structure and convenient for processing and assembly.

[0038] In the embodiment, the first guide portion 61 and the first guide groove each have two and are arranged one by one, the two first guide portions 61 are arranged at the two ends of the first extrusion member 40 along the radial direction, and the two first guide grooves are arranged on the inner side wall of the die sleeve 10 correspondingly. Further, the second guide structure comprises a second guide groove and a second guide portion 71. The second guide groove is arranged on one of the second extrusion member 50 and the die sleeve 10, and extends along the movement direction of the second extrusion member 50. The second guide portion 71 is arranged on the other one of the second extrusion member 50 and the die sleeve 10, at least part of the second guide portion 71 is located in the second guide groove, and the second guide portion 71 is guided and matched with the second guide groove. Through the cooperation of the second guide groove and the second guide portion 71, the stable guidance of the second extrusion member 50 during the extrusion process is realized, and the possible deviation of the extrusion member in the high-temperature and high-pressure environment is avoided.

[0039] In some embodiments, the first guide groove and the second guide groove may be configured as a through groove that is interconnected.

[0040] Specifically, there are two second guide portions 71 and two guide grooves, which are arranged in a one-to-one correspondence. The two second guide portions 71 are respectively arranged at both ends of the second extruder 50 in the circumferential direction, and the two second guide grooves are respectively arranged on the inner side wall of the mold sleeve 10.

[0041] The first guide portion 61 and the second guide portion 71 can be configured as sliders, protrusions, or other structures. In this embodiment, the first guide portion 61 and the second guide portion 71 are configured as guide sliders extending along the cavity 101. This not only increases the contact area between the first guide portion 61 and the first guide groove, and the contact area between the second guide portion 71 and the second guide groove, but also, when necessary, limits the movement of the first extruder 40 and the second extruder 50.

[0042] In some embodiments, the diameter of the first pressure head 20 is greater than or less than the diameter of the second pressure head 30. This configuration allows for the production of two magnetic rings with different inner diameters in a single extrusion process, reducing operational steps and energy consumption, while also shortening the production cycle, thereby improving the production efficiency and economic benefits of the apparatus.

[0043] In other embodiments, the diameter of the first pressure head 20 is equal to the diameter of the second pressure head 30.

[0044] like Figure 2 As shown, the end of the second pressure head 30 furthest from the blank 01 has a constricted section 31. Thus, when demolding occurs on one side of the second pressure head 30, the presence of the constricted section 31 gradually reduces the contact area between the second pressure head 30 and the magnetic ring during demolding, thereby reducing the friction and adhesion between the magnetic ring and the second pressure head 30, making the demolding process easier and safer. Compared to a right-angled or straight contact surface between the pressure head and the magnetic ring, which is prone to scratches or cracks on the inner wall of the magnetic ring during demolding, the constricted section 31 design of this application provides a smooth transition, reducing damage to the surface of the magnetic ring and ensuring the surface quality and integrity of the product.

[0045] Specifically, the edge of the end face of the first pressing head 20 and / or the second pressing head 30 is a circular arc transition. Specifically, the end of the first pressing head 20 connected to the hot press is a connecting end, the end of the first pressing head 20 in contact with the blank 01 is an extrusion end, and the connection between the extrusion end and the connecting end is a circular arc transition. Through the above arrangement, the first pressing head 20 and the second pressing head 30 can stably contact the blank 01 during extrusion, avoiding stress concentration in the blank 01 caused by sharp edges, reducing cracks and defects in the blank 01, and improving the stability of the extrusion process and the surface quality and magnetic properties of the product. And the above structure can reduce the adhesion of the pressing head to the blank 01, ensuring the integrity of the product.

[0046] Further, the end face of the first pressing head 20 and / or the second pressing head 30 close to the blank 01 is a plane. This can further optimize the pressure distribution, ensure uniform pressure on the blank 01, and avoid uneven stress distribution in the blank 01 caused by irregular end face shape, improving the surface quality of the product.

[0047] When using the magnetic ring hot extrusion forming device provided by the first embodiment of the present application to process the blank 01, the specific steps are as follows: the inner wall of the die sleeve 10, the surface of the first pressing head 20 and the second pressing head 30, and the surface of the first extrusion piece 40 and the second extrusion piece 50 are all sprayed with graphite release agent; a blank 01 with a weight of 200g, a diameter of 30mm and a height of 20mm is placed in the cavity 101, on the second pressing head 30, and the second extrusion piece 50 is 30mm away from the lower end of the blank 01; adjust the lower end of the first pressing head 20 to be flush with the upper end of the blank 01, and the first extrusion piece 40 is placed 30mm away from the upper end of the blank; after vacuumizing by the hot press, the inductive coil outside the die sleeve 10 is heated to 800℃, and after 2min of heat preservation, the first pressing head 20 and the second pressing head 30 move towards the blank 01 at a speed of 0.01mm / s-0.03mm / s, stop moving when the deformation of the blank 01 is 63%, and the first extrusion piece 40 and the second extrusion piece 50 start to move towards the blank 01 at a speed of 0.005mm / s-0.01mm / s, the contact with the blank 01 is calculated, and the movement is stopped after 3mm; then cool down, and get an H-shaped magnetic ring with a height of 36.8mm after demolding, and two anisotropic neodymium-iron-boron magnetic rings with an inner diameter of 24.5mm and 22.3mm, an outer diameter of 30mm, and a height of 16mm are obtained after cutting.

[0048] Specifically, the moving speed of the first and second pressing heads 20 and 30 is limited to 0.01-0.03 mm / s. If the moving speed of the first and second pressing heads 20 and 30 is lower than 0.01 mm / s, the moving speed of the pressing heads is too slow, which can cause the heating time of the blank 01 in the die set 10 to be too long, and can easily cause the grain size of the blank 01 to be too large, and reduce the magnetic performance of the magnetic ring. If the moving speed of the first and second pressing heads 20 and 30 is higher than 0.03 mm / s, the moving speed of the pressing heads is too fast, which can easily cause the blank 01 to crack during extrusion, and affect the product quality. Therefore, in the present application, the moving speed of the first and second pressing heads 20 and 30 is limited to 0.01-0.03 mm / s, which can avoid the moving speed of the pressing heads being too fast to cause the blank 01 to crack, and can also avoid the heating time of the blank 01 being too long to affect the magnetic performance of the magnetic ring, and improve the comprehensive performance of the magnetic ring. Specifically, the moving speed of the first and second pressing heads 20 and 30 can be set to 0.01, 0.02 or 0.03 mm / s, etc.

[0049] The moving speed of the first and second extruding members 40 and 50 is limited to 0.005-0.01 mm / s, which is lower than the moving speed of the first and second pressing heads 20 and 30. This is to more accurately control the moving precision of the first and second extruding members 40 and 50, and to make the moving distance more accurate. If the moving speed of the first and second extruding members 40 and 50 is lower than 0.005 mm / s, the moving speed of the extruding members is too slow, which can cause the heating time of the blank 01 in the die set 10 to be too long, and can easily cause the grain size of the blank 01 to be too large, and reduce the magnetic performance of the magnetic ring. If the moving speed of the first and second extruding members 40 and 50 is higher than 0.01 mm / s, the moving speed of the extruding heads is too fast, which can easily cause the blank 01 to crack during extrusion, and affect the product quality. Therefore, in the present application, the moving speed of the first and second extruding members 40 and 50 is limited to 0.005-0.01 mm / s, which can avoid the moving speed of the extruding heads being too fast to cause the blank 01 to crack, and can also avoid the heating time of the blank 01 being too long to affect the magnetic performance of the magnetic ring, and improve the comprehensive performance of the magnetic ring. Specifically, the moving speed of the first and second extruding members 40 and 50 can be set to 0.005, 0.008 or 0.01 mm / s, etc.

[0050] When the first and second extruding members 40 and 50 move towards the blank 01 at a speed of 0.01 mm / s, the moving speed is calculated from the time when the first and second extruding members 40 and 50 contact the blank 01, and stops moving after moving 5 mm. After demolding, an H-shaped magnetic ring with a height of 32.5 mm can be obtained, and two anisotropic neodymium-iron-boron magnetic rings with an inner diameter of 24.5 mm and 22.3 mm, an outer diameter of 30 mm, and a height of 14 mm can be obtained after cutting.

[0051] The size of the blank 01, the initial distance between the first extrusion 40 and the second extrusion 50 and the blank 01, the moving speed of the first pressure head 20, the second pressure head 30, the first extrusion 40 and the second extrusion 50, the extrusion degree of the blank 01, temperature and other parameters can be adjusted according to actual needs.

[0052] As shown in Figure 3 and Figure 4 The second embodiment of the present application provides a magnetic ring hot extrusion forming device, which is different from the first embodiment in that the magnetic ring hot extrusion forming device further comprises a plug-in slot 81 and a plug-in head 91. The plug-in slot 81 is arranged on the end face of the first pressure head 20 close to the blank 01. The plug-in head 91 is arranged on the end face of the second pressure head 30 close to the blank 01, and the plug-in head 91 is arranged correspondingly with the plug-in slot 81, and the plug-in head 91 can be plugged into the plug-in slot 81 through the blank 01. Thus, the blank 01 can be penetrated through by the mutual cooperation of the plug-in slot 81 and the plug-in head 91, and a complete magnetic ring can be directly obtained, and then two or more magnetic rings can be obtained by subsequent cutting. Compared with the first embodiment in which the first pressure head 20 and the second pressure head 30 do not contact, there is excess material in the middle of the cut product, the processing and cutting of the material are small, the setting of the second embodiment can reduce unnecessary material waste and reduce the processing and post-processing cost.

[0053] By simply changing the structure or size of the first pressure head 20, magnetic rings with different inner diameters can be obtained, which is very convenient to operate.

[0054] Preferably, the plug-in slot 81 and the plug-in head 91 are coaxially arranged, which can improve the plugging precision of the two.

[0055] The radial cross-sectional area of the plug-in head 91 gradually decreases towards the blank 01. In this way, the contact area between the plug-in head 91 and the blank 01 is smaller, and the friction and resistance to be overcome are also relatively smaller, which simplifies the plugging operation, and the hot press can more easily insert it into the blank 01, reducing the operation difficulty and time. And the above structure makes the contact area of the second pressure head 30 gradually increase during the plugging into the blank 01, and this gradual contact makes the material of the blank 01 gradually adapt to the plugging of the plug-in head, significantly reducing the resistance during plugging, avoiding the local stress concentration and possible crack formation caused by the sudden change of the contact area, thereby improving the integrity of the blank 01 and the yield of the finished product after demolding.

[0056] In the process of using the magnetic ring hot extrusion forming device provided in Embodiment Two of the present application to process the blank 01, the specific steps are as follows: the magnetic powder used in this embodiment is the same as that used in Embodiment One. When the temperature reaches 700-900℃, the first pressing head 20 and the first extruding piece 40 are flush with the end of the blank 01, the first pressing head 20 and the first extruding piece 40 move towards the blank 01 at the same speed of 0.02mm / s, the second extruding piece 50 and the second pressing head 30 are flush with the end of the blank 01, and the moving speed is 0.01mm / s. When the distance from the bottom of the die set 10 reaches 830mm, the position of the second extruding piece 50 is fixed and the movement is stopped, and the second pressing head 30 continues to move upwards, slowly passing through the heated blank 01 through the adapter 91 and entering the adapter slot 81 of the first pressing head 20. At this time, the blank 01 forms a ring shape. When the set position is reached, the blank 01 is compressed, and then cooled. After demolding, a magnetic ring with an inner diameter of 22.3mm, an outer diameter of 30mm, and a height of 25mm is obtained.

[0057] Among them, the size of the blank 01, the initial distance of the first extruding piece 40 and the second extruding piece 50 from the blank 01, the moving speed of the first pressing head 20, the second pressing head 30, the first extruding piece 40 and the second extruding piece 50, the extrusion degree of the blank 01, the temperature and other parameters can be adjusted according to actual needs.

[0058] In order to better understand the technical solutions of the present application, the two groups of size magnetic rings obtained in Embodiment One of the present application are respectively taken as Embodiment 1.1 and Embodiment 1.2, and the magnetic ring obtained in Embodiment Two of the present application is taken as Embodiment 2. Then, the magnetic ring obtained by using the magnetic ring hot extrusion forming device in the prior art is taken as Comparative Example 1 and Comparative Example 2. The specific data of the comparative examples are as follows:

[0059] Comparative Example 1:

[0060] The blank used in this comparative example is the same as that used in the embodiments. The hot extrusion magnetic ring preparation device used in this comparative example is a general back extrusion magnetic ring device, which includes a hot extrusion pressing head, a hot extrusion ring mold, and a resistance wire furnace body heating. One hot deformation magnetic ring is prepared by one-time furnace body heating. The specific implementation steps are as follows: the inner wall of the hot extrusion ring mold and the surface of the hot extrusion pressing head are sprayed with a release agent; a blank with a weight of 200g, a diameter of 30mm, and a height of 20mm is placed in the hot extrusion ring mold, and the lower end of the hot extrusion pressing head is adjusted to be flush with the upper end of the hot pressing magnet blank; after vacuumizing, heating is carried out to 800℃, and after 2min of heat preservation, the hot extrusion pressing head moves downward at a speed of 0.03mm / s to a deformation of 70%, and then the pressing head movement is stopped; cooling, and after demolding, a cup-shaped magnet with a height of 35.7mm is obtained. After cutting, one anisotropic neodymium-iron-boron magnetic ring with an inner diameter of 24.5mm, an outer diameter of 30mm, and a height of 28mm is obtained.

[0061] Comparative Example 2:

[0062] The blank used in this comparative example is the same as that used in the example. The difference between this comparative example and Example 1.1 is that the hot extrusion temperature is 750℃, and after holding at that temperature for 2 minutes, the hot extrusion head moves downward at a rate of 0.02 mm / s until the deformation is 68%, at which point the head movement is stopped; after cooling and demolding, a cup-shaped magnet with a height of 33.5 mm is obtained, which is then cut to obtain an anisotropic neodymium iron boron magnetic ring with an inner diameter of 24.5 mm, an outer diameter of 30 mm, and a height of 27 mm.

[0063] Performance tests were conducted on the hot-extruded NdFeB permanent magnet rings prepared in the various embodiments and comparative examples of this application, such as... Figure 5 As shown, cylinders with a diameter of 2 mm were cut out at three positions: top position 02, middle position 03, and bottom position 04 of a magnetic ring. A vibrating sample magnetometer (VSM) was used to test the remanence (Br), intrinsic coercivity (Hcj), and maximum energy product ((BH)max). The test results are shown in the table below.

[0064]

[0065]

[0066] As can be seen from the table above, the magnetic properties of the magnetic rings prepared in the three sets of examples are all higher than those in Comparative Examples 1 and 2. In addition, the grain orientation degree of the top and middle parts of the examples is improved, the difference in magnetic properties between the top, middle and bottom positions is reduced, and the problem of magnetic inhomogeneity is improved.

[0067] The technical solution provided in this application has the following advantages:

[0068] 1. At high temperatures of 700℃~900℃, the billet is in a rheological state due to the presence of a low-melting-point neodymium-rich phase. Under the force of the indenter, the billet extends along the space between the indenter and the inner wall of the die. The greater the pressure, the smaller the difference in density, orientation, and magnetic properties of the magnetic ring from bottom to top. By adding movable extrusion parts above and below the billet, when the deformation of the billet reaches 50%~70%, the two extrusion parts and two indenters move towards the billet, enhancing the density and grain orientation of the top of the magnetic ring, improving the anisotropy of the magnet, and enhancing the overall magnetic properties. Furthermore, the rounded transition at the end of the indenter reduces the problem of cracking on the inner wall of the magnetic ring.

[0069] 2. Existing magnetic ring hot extrusion forming equipment uses a set of molds to prepare magnetic rings of a single size. This application utilizes the diversity of diameters of two pressure heads to prepare magnetic rings of two different inner diameter sizes at one time, producing H-shaped magnets with a longitudinal section. Multiple high-performance magnetic rings can be cut out, and magnetic rings of different weight specifications can be obtained by simply changing the pressure heads. The operation is flexible and convenient.

[0070] 3. Only one additional first pressure head with a plug slot is needed to obtain three different sizes of magnetic rings, and the amount of material removed during processing is small, reducing the cost of mold processing and post-processing.

[0071] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0072] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0073] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0074] For purposes of the description hereinafter, spatial relative terms, such as "above", "below", "upper", "lower", and the like, can be used to describe the relative position of one element or feature to another as illustrated in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0075] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not connote any meaning of importance, but are used solely to differentiate one element from another, and are used in the context of this application without implying any specific order, or order of precedence. Accordingly, a first element that follows an operation can be performed before, after, or at the same time as a second element that precedes the operation.

[0076] The preferred embodiments of the present application have been described above with the purpose of enabling not only the best modes of practicing the application known to the inventors at this time, but also of enabling others skilled in the art to utilize the application in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, the above description is intended to be illustrative, but not restrictive, of the scope of the present application. All patents and patent applications mentioned herein are incorporated by reference in their entirety.

Claims

1. A magnetic ring hot extrusion forming apparatus characterized by comprising: The magnetic ring hot extrusion forming device comprises: a die sleeve (10) having a cavity (101) capable of placing a blank (01); a first pressure head (20) and a second pressure head (30) movably arranged on both sides of the blank (01) along the extension direction of the cavity (101), the first pressure head (20) and the second pressure head (30) being capable of providing the blank (01) with forces in opposite directions, the first pressure head (20) and the second pressure head (30) being respectively connected with a hot press; a first extrusion piece (40) and a second extrusion piece (50) movably arranged in the cavity (101) along the extension direction of the cavity (101), the first extrusion piece (40) and the second extrusion piece (50) being respectively arranged in one-to-one correspondence with the first pressure head (20) and the second pressure head (30), the first extrusion piece (40) being sleeved on the circumferential outer periphery of the first pressure head (20), the second extrusion piece (50) being sleeved on the circumferential outer periphery of the second pressure head (30), the first pressure head (20), the second pressure head (30), the first extrusion piece (40), the second extrusion piece (50) and the inner side wall of the die sleeve (10) cooperating to form an extrusion cavity (102) for extrusion forming the blank (01), the first extrusion piece (40) and the second extrusion piece (50) being respectively connected with the hot press.

2. The magnetic ring hot extrusion forming apparatus according to claim 1, wherein The magnetic ring hot extrusion forming device further comprises: a first guide structure arranged between the first extrusion piece (40) and the die sleeve (10), the extension direction of the first guide structure being the same as the extension direction of the cavity (101), the first guide structure being used for guiding the moving direction of the first extrusion piece (40); a second guide structure arranged between the second extrusion piece (50) and the die sleeve (10), the extension direction of the second guide structure being the same as the extension direction of the cavity (101), the second guide structure being used for guiding the moving direction of the second extrusion piece (50).

3. The magnetic ring hot extrusion forming apparatus according to claim 2, wherein The first guide structure comprises: a first guide groove arranged on one of the first extrusion piece (40) and the die sleeve (10), the first guide groove extending along the moving direction of the first extrusion piece (40); a first guide part (61) arranged on the other of the first extrusion piece (40) and the die sleeve (10), at least part of the first guide part (61) being located in the first guide groove and guidingly cooperating with the first guide groove.

4. The magnetic ring hot extrusion forming apparatus according to claim 2, wherein The second guide structure comprises: a second guide groove arranged on one of the second extrusion piece (50) and the die sleeve (10), the second guide groove extending along the moving direction of the second extrusion piece (50); a second guide part (71) arranged on the other of the second extrusion piece (50) and the die sleeve (10), at least part of the second guide part (71) being located in the second guide groove and guidingly cooperating with the second guide groove.

5. The magnetic ring hot extrusion forming apparatus according to claim 1, wherein The magnetic ring hot extrusion forming device further comprises: A plug-in slot (81) arranged on the end face of the first pressing head (20) close to the blank (01); A plug-in head (91) arranged on the end face of the second pressing head (30) close to the blank (01), the plug-in head (91) is correspondingly arranged with the plug-in slot (81), and the plug-in head (91) can be plugged into the plug-in slot (81) through the blank (01).

6. The magnetic ring hot extrusion forming device according to claim 5, wherein, The radial cross-sectional area of the plug-in head (91) gradually decreases in the direction close to the blank (01).

7. The magnetic ring hot extrusion forming device according to claim 1, wherein, The diameter of the first pressing head (20) is greater than or less than the diameter of the second pressing head (30).

8. The magnetic ring hot extrusion forming device according to claim 1, wherein, The end of the second pressing head (30) away from the blank (01) has a necked section (31).

9. The magnetic ring hot extrusion forming device according to claim 1, wherein, The edge of the end face of the first pressing head (20) and / or the second pressing head (30) is a circular arc transition.

10. The magnetic ring hot extrusion forming device according to claim 1, wherein, The end face of the first pressing head (20) and / or the second pressing head (30) close to the blank (01) is a plane.

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