A forming method and device for a radiation-oriented sintered magnetic ring

Abstract

The present invention relates to a forming device and method for a radiation-oriented sintered magnetic ring, belonging to the technical field of magnetic ring processing. A forming device for sintering a radiation-oriented magnetic ring includes a forming unit composed of an inner magnetic pole, an annular die cavity, a die sleeve, and an outer magnetic pole arranged from the inside out; the number of forming units is more than 2, the annular die cavities of different forming units are arranged in parallel, and the pole heads of the outer magnetic poles close to one end of the annular die cavity around the same annular die cavity have the same polarity and are opposite to the polarity of the corresponding inner magnetic pole. When manufacturing a radiation-oriented magnetic ring according to the present invention, each orientation magnetic field is provided separately by a coil with current and a soft magnetic material, effectively suppressing the reduction of the magnetic field caused by the magnetic leakage problem in the single-coil plus yoke iron magnetic conduction mode; the pole heads of the outer magnetic poles around the same annular die cavity have the same polarity, improving the orientation degree of the magnetic ring and the orientation uniformity of the magnetic ring in the circumferential direction of the annular die cavity. At least 2 magnetic rings can be formed simultaneously, and the forming efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic ring processing, and in particular to a forming device and method for a radiation-oriented sintered magnetic ring. Background Art

[0002] Due to its advantages such as compact structure, no tangential magnetic flux component, and stable output waveform, the integral radial magnetic ring has wide applications in fields such as motors and magnetic encoders. The biggest technical difficulty in manufacturing sintered radial magnetic rings is the orientation and forming of magnetic powder.

[0003] At present, the preparation of radial magnetic rings generally adopts two methods. One is to generate a radiation-oriented magnetic field by using the principle of like poles repelling each other. This method can ensure a certain degree of uniformity of the magnetic ring in the circumferential direction. However, when the inner diameter of the radial ring is small, the intensity of the oriented magnetic field will be greatly reduced, resulting in incomplete orientation of the magnetic powder. At the same time, for magnetic rings with a large length-diameter ratio, the uniformity in the axial direction is poor. The other is to introduce the two poles of the magnetic field into the inner-outer poles or outer-outer poles respectively through a magnetic conduction device, and then obtain the magnetic ring through the rotational orientation of the magnetic powder and the magnetic field. Due to the long magnetic path, the leakage magnetic effect leads to a low intensity of the oriented magnetic field. In addition, the oriented magnetic field only occupies a very small part of the 360° angle of the circular ring. Therefore, the magnetic powder needs to complete a relative movement of more than 360° with the oriented field to achieve complete orientation of the entire magnetic ring. When using a single outer pole for orientation, there are differences in the difficulty of orientation at different positions on the circumference of the magnetic ring, resulting in non-uniform orientation of the magnetic ring in the circumferential direction. When using multiple outer poles for orientation, the polarities of different outer poles are opposite. During the relative rotational movement of the magnetic powder and the oriented magnetic field, the magnetic powder will be repeatedly subjected to the action of suction and repulsion forces, not only greatly reducing the orientation degree of the magnetic ring, but also greatly reducing the orientation uniformity of the magnetic ring in the circumferential direction. Therefore, there is an urgent need for a forming method for oriented magnetic rings to solve the problems of low orientation degree and poor orientation uniformity of existing magnetic ring forming methods. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a forming device and method for a radiation-oriented sintered magnetic ring to solve one of the problems of low orientation degree, poor orientation uniformity, and poor surface field consistency of magnetic rings prepared by existing magnetic ring forming methods.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A forming device for a sintered radiation-oriented magnetic ring includes a forming unit composed of an inner magnetic pole, an annular die cavity, a die sleeve, and an outer magnetic pole arranged from the inside to the outside;

[0007] The number of the forming units is more than 2. The annular die cavities of different forming units are arranged in parallel. The pole heads at one end of the outer magnetic poles surrounding the same annular die cavity have the same polarity and are opposite to the polarity of the corresponding inner magnetic pole.

[0008] Further, each inner magnetic pole is respectively composed of a current-carrying coil, a soft magnetic material, and a magnetic core rod. The polarities of adjacent inner magnetic poles are opposite, and adjacent inner magnetic poles share at least one outer magnetic pole.

[0009] Further, the number of the outer magnetic poles of the forming unit is N, where N≥4. Each outer magnetic pole is composed of a current-carrying coil, a soft magnetic material, and a pole head. The outer magnetic poles are distributed uniformly or non-uniformly on the 360° circumference around the annular cavity. The number of outer magnetic poles around each annular cavity is a, b, c…n respectively, and satisfies ∑(a, b, c…n) = N.

[0010] Further, the sum of the widths of the pole heads of the outer magnetic poles around the same annular cavity is W, and the diameter of the magnetic core rod of the corresponding inner magnetic pole is d, and satisfies W≤1 / 2(d*π), where the units of W and d are mm.

[0011] Further, the sum of the magnetic fluxes of the pole heads of the outer magnetic poles around the same annular cavity is Φ, the sum of the magnetic fluxes of the corresponding inner magnetic pole and the upper end face of the annular cavity is Φ 内上 , and the sum of the magnetic fluxes of the corresponding inner magnetic pole and the lower end face of the annular cavity is Φ 内下 , and satisfies Φ≤Φ 内上 +Φ 内下 .

[0012] Further, the device includes a first die sleeve, a second die sleeve, a first annular cavity, a second annular cavity, a first inner magnetic pole, a second inner magnetic pole, a first outer magnetic pole, a second outer magnetic pole, a third outer magnetic pole, and a fourth outer magnetic pole;

[0013] The first inner magnetic pole and the second inner magnetic pole are respectively composed of a current-carrying coil, a soft magnetic material, and a magnetic core rod, and the polarities of the first inner magnetic pole and the second inner magnetic pole are opposite;

[0014] The first outer magnetic pole, the second outer magnetic pole, the third outer magnetic pole, and the fourth outer magnetic pole are all composed of a current-carrying coil, a soft magnetic material, and a pole head, and the first inner magnetic pole and the second inner magnetic pole share the third outer magnetic pole;

[0015] The first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole are distributed uniformly on the 360° circumference around the first annular cavity, and the included angle between adjacent outer magnetic poles is 120°. The polarities of the pole heads of the three outer magnetic poles close to the first annular cavity are the same and opposite to the polarity of the first inner magnetic pole;

[0016] The third outer magnetic pole and the fourth outer magnetic pole are distributed non-uniformly on the 360° circumference around the second annular cavity. Along the counterclockwise direction of the third outer magnetic pole, the included angle between the third outer magnetic pole and the fourth outer magnetic pole is 160°. The polarities of the pole heads of the two outer magnetic poles close to the second annular cavity are the same and opposite to the polarity of the second inner magnetic pole.

[0017] Furthermore, the first annular cavity and the second annular cavity are arranged in parallel. The first annular cavity is located between the first inner magnetic pole and the first die sleeve, and the second annular cavity is located between the second inner magnetic pole and the second die sleeve. Connecting the midpoints of the end faces of several outer magnetic pole heads around the same annular cavity with lines can form a circle, and the center of this circle coincides with the center of the surrounded annular cavity.

[0018] Furthermore, the first die sleeve and the second die sleeve are annular and are respectively arranged around the first annular cavity and the second annular cavity. The first die sleeve and the first annular cavity are in the same plane, and the second die sleeve and the second annular cavity are in the same plane.

[0019] The magnetic conduction core rods of the first die sleeve, the first annular cavity and the first inner magnetic pole are coaxial, and the magnetic conduction core rods of the second die sleeve, the second annular cavity and the second inner magnetic pole are coaxial.

[0020] The magnetic conduction core rod of the first inner magnetic pole is perpendicular to the plane where the first die sleeve and the first annular cavity are located. One end of the magnetic conduction core rod is coplanar with the lower end faces of the first die sleeve and the first annular cavity, and the other end of the magnetic conduction core rod is coplanar with the upper end faces of the first die sleeve and the first annular cavity or higher than the upper end face.

[0021] The magnetic conduction core rod of the second inner magnetic pole is perpendicular to the plane where the second die sleeve and the second annular cavity are located. One end of the magnetic conduction core rod is coplanar with the lower end faces of the second die sleeve and the second annular cavity, and the other end of the magnetic conduction core rod is coplanar with the upper end faces of the second die sleeve and the second annular cavity or higher than the upper end face.

[0022] A forming method for a sintered oriented magnetic ring, which is realized by the above-mentioned forming equipment, includes the following steps:

[0023] Step 1: Put magnetic powder into the annular cavity, and introduce the magnetic fields generated by the coils with current passing through and soft magnetic materials into multiple outer magnetic poles surrounding the annular cavity through the magnetic conduction pole heads respectively, and introduce them into the corresponding inner magnetic poles through the magnetic conduction core rods respectively, so as to form multiple orientation magnetic fields between the inner magnetic poles and the outer magnetic poles.

[0024] Step 2: Drive the die sleeve, the pressure head, the magnetic conduction core rod of the inner magnetic pole and the magnetic powder of a single forming unit to rotate coaxially simultaneously through the servo motor to complete the magnetization and orientation of the magnetic powder in the corresponding annular cavity. During the orientation process, the upper pressure head and the lower pressure head of the pressure head move towards each other or in the same direction while rotating, applying a gradually increasing pressure to the magnetic powder to complete the pressing and forming of the magnetic powder.

[0025] Furthermore, the intensity of the orientation magnetic field ≥ 1.2T, and / or the rotation speed of the servo motor is 50 - 500 r / min; and / or the speed of the upper pressure head and the lower pressure head of the pressure head moving towards each other or in the same direction while rotating is 30 m / s - 70 m / s.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] 1. When manufacturing a radially oriented magnetic ring by the forming method of the present invention, each orientation magnetic field is independently provided by a coil with current and soft magnetic material, effectively suppressing the reduction of the magnetic field caused by the magnetic leakage problem in the single-coil plus yoke iron magnetic conduction mode; at the same time, a high orientation magnetic field value can be ensured, thereby improving the orientation degree of the magnetic ring during the forming process; the polarities of the outer magnetic pole heads around the same annular cavity are the same, ensuring that during the relative rotational movement of the magnetic powder and the orientation magnetic field, the magnetic powder is always subjected to a suction force, improving the orientation degree of the magnetic ring and the orientation uniformity of the magnetic ring in the circumferential direction of the annular cavity, and avoiding the problem that in the prior art, when the polarities of the outer magnetic poles are opposite and the magnetic powder and the orientation magnetic field are in relative rotational movement, the magnetic powder will be repeatedly subjected to suction and repulsion forces, not only greatly reducing the orientation degree of the magnetic ring, but also greatly reducing the orientation uniformity of the magnetic ring in the circumferential direction.

[0028] 2. When manufacturing a radially oriented magnetic ring by the forming method of the present invention, multiple high-strength orientation magnetic fields are used to perform rotational orientation on the magnetic ring. Each time the magnetic powder in each annular cavity rotates one week, it obtains multiple magnetic field orientation pressings, improving the surface field consistency of the magnetic ring in the circumferential direction. The present invention simultaneously completes the orientation forming of the magnetic powder through at least two annular cavities arranged in parallel. Through the simultaneous orientation of multiple inner magnetic poles and outer magnetic poles, the efficiency of magnetic powder orientation forming is improved, and at least 2 magnetic rings can be formed simultaneously. Compared with the magnetic rings formed by the existing method, it has a higher surface field, a lower surface field peak deviation, and a higher surface field consistency.

[0029] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the content specifically pointed out in the description and the drawings. Description of the Drawings

[0030] The drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference signs denote the same components.

[0031] Figure 1 Schematic diagram of the forming of a radially oriented magnetic ring by magnetic field rotation orientation for an embodiment.

[0032] Reference Signs:

[0033] 1 - First outer magnetic pole; 2 - First inner magnetic pole; 3 - First die sleeve; 4 - Second outer magnetic pole; 5 - First annular cavity; 6 - Third outer magnetic pole; 7 - Second inner magnetic pole; 8 - Second die sleeve; 9 - Second annular cavity; 10 - Fourth outer magnetic pole. Detailed Embodiments

[0034] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0035] The present invention provides a forming device for a sintered radiation-oriented magnetic ring, including a forming unit composed of an inner magnetic pole, an annular mold cavity, a mold sleeve, and an outer magnetic pole arranged from the inside out.

[0036] The number of forming units is more than 2. The annular mold cavities of different forming units are arranged in parallel. The pole heads at one end of the outer magnetic poles around the same annular mold cavity have the same polarity and are opposite to the polarity of the corresponding inner magnetic poles.

[0037] Each inner magnetic pole is respectively composed of a coil through which current passes, a soft magnetic material, and a magnetic core rod. The polarities of adjacent inner magnetic poles are opposite, and adjacent inner magnetic poles share at least one outer magnetic pole.

[0038] The number of outer magnetic poles of a single forming unit is N, N≥4. Each outer magnetic pole is respectively composed of a coil through which current passes, a soft magnetic material, and a pole head. The outer magnetic poles are evenly or unevenly distributed on the 360° circumference around the annular mold cavity. The number of outer magnetic poles around each annular mold cavity is a, b, c…n respectively, satisfying ∑(a, b, c…n) = N. Connecting the midpoints of the end faces of the pole heads of several outer magnetic poles around the same annular mold cavity with lines can form a circle, and the center of this circle overlaps with the center of the annular mold cavity it surrounds.

[0039] The sum of the widths of the pole heads of the outer magnetic poles around the same annular mold cavity is W, and the diameter of the magnetic core rod of the corresponding inner magnetic pole is d, satisfying W≤ 1 / 2(d*π), where the units of W and d are mm; it should be noted that there is an upper limit value for the magnetic flux of the inner magnetic pole, which limits the magnitude of the orientation magnetic field. When preparing a magnetic ring with a smaller inner diameter size, if the width of the pole head of the outer magnetic pole is too large, the formed orientation magnetic field is relatively dispersed. Satisfying W≤ 1 / 2(d*π) can make the formed orientation magnetic field sufficiently concentrated.

[0040] The sum of the magnetic fluxes of the pole heads of the outer magnetic poles around the same annular mold cavity is Φ, the sum of the magnetic fluxes of the corresponding inner magnetic pole and the upper end face of the annular mold cavity is Φ 内上 , and the sum of the magnetic fluxes of the corresponding inner magnetic pole and the lower end face of the annular mold cavity is Φ 内下 , satisfying Φ≤Φ 内上 +Φ 内下This is because the orientation magnetic fields are all closed. If this condition is not met, resulting in the total magnetic flux of all outer magnetic pole heads being greater than the total magnetic flux of the inner magnetic pole and the upper and lower planes of the annular cavity, a large amount of magnetic leakage will occur, which will not only reduce the orientation degree of magnetic powder in the annular cavity but also cause energy waste of the current forming the orientation magnetic field. The magnetic fluxes of the inner and outer magnetic poles can be achieved by adjusting the current magnitudes in the inner magnetic pole and / or each outer magnetic pole.

[0041] The die sleeves are annular and are respectively arranged around the corresponding annular cavities. The matching die sleeves and the corresponding annular cavities are in the same plane. The matching die sleeves, the corresponding annular cavities, and the magnetic conduction mandrels of the corresponding inner magnetic poles are coaxial. The magnetic conduction mandrels of the corresponding inner magnetic poles are perpendicular to the planes where the corresponding die sleeves and the corresponding annular cavities are located. One end of the magnetic conduction mandrel is coplanar with the lower end surface of the corresponding die sleeve and the annular cavity, and the other end of the magnetic conduction mandrel is coplanar with the upper end surface of the corresponding die sleeve and the annular cavity or higher than the upper end surface. The inner diameter of the die sleeve is the same as the outer diameter size of the magnetic ring to be prepared, and the wall thickness (outer diameter = inner diameter + wall thickness) is generally required to be ≥10 mm.

[0042] Preferably, the present invention provides a forming device for sintered radiation-oriented magnetic rings, including: a first die sleeve, a second die sleeve, a first annular cavity, a second annular cavity, a first inner magnetic pole, a second inner magnetic pole, a first outer magnetic pole, a second outer magnetic pole, a third outer magnetic pole, and a fourth outer magnetic pole;

[0043] The first inner magnetic pole and the second inner magnetic pole are respectively composed of a current-carrying coil, a soft magnetic material, and a magnetic conduction mandrel, and the first inner magnetic pole and the second inner magnetic pole have opposite polarities;

[0044] The first outer magnetic pole, the second outer magnetic pole, the third outer magnetic pole, and the fourth outer magnetic pole are all composed of a current-carrying coil, a soft magnetic material, and a pole head. The first inner magnetic pole and the second inner magnetic pole share the third outer magnetic pole; sharing the same outer magnetic pole can reduce the usage amount of the separately energized current plus the soft magnetic material;

[0045] The first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole are evenly distributed around the first annular cavity on a 360° circumference, and the included angle between adjacent outer magnetic poles is 120°. The polarities of the pole heads of the three outer magnetic poles close to the first annular cavity are the same and opposite to the polarity of the first inner magnetic pole;

[0046] The third outer magnetic pole and the fourth outer magnetic pole are unevenly distributed around the second annular cavity on a 360° circumference. Along the counterclockwise direction of the third outer magnetic pole, the included angle between the third outer magnetic pole and the fourth outer magnetic pole is 160°. The polarities of the pole heads of the two outer magnetic poles close to the second annular cavity are the same and opposite to the polarity of the second inner magnetic pole;

[0047] The widths of the first outer magnetic pole, the second outer magnetic pole, the third outer magnetic pole, and the fourth outer magnetic pole heads are W1, W2, W3, and W4 respectively, with the unit of mm; the diameters of the magnetic core rods of the first inner magnetic pole and the second inner magnetic pole are d1 and d2 respectively, with the unit of mm; and it satisfies ∑(W1, W2, W3) ≤ 1 / 2(d1*π), ∑(W3, W4) ≤ 1 / 2(d2*π); it should be noted that there is an upper limit for the magnetic flux of the inner magnetic pole, which limits the magnitude of the orientation magnetic field. When preparing a magnetic ring with a smaller inner diameter, if the width of the outer magnetic pole head is too large, the formed orientation magnetic field will be relatively dispersed. Satisfying ∑(W1, W2, W3) ≤ 1 / 2(d1*π), ∑(W3, W4) ≤ 1 / 2(d2*π) can make the formed orientation magnetic field sufficiently concentrated.

[0048] The first annular cavity and the second annular cavity are arranged in parallel for filling magnetic powder. The first annular cavity is located between the first inner magnetic pole and the first mold sleeve, and the second annular cavity is located between the second inner magnetic pole and the second mold sleeve; connecting the midpoints of the end faces of several outer magnetic pole heads around the same annular cavity with a line can form a circle, and the center of this circle coincides with the center of the surrounded annular cavity;

[0049] The first inner magnetic pole and the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole surrounding the first annular cavity satisfy: ∑(Φ1, Φ2, Φ3) ≤ Φ 内1上 +Φ 内1下 ; where Φ1, Φ2, and Φ3 are the magnetic fluxes of the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole heads respectively; Φ 内1上 is the magnetic flux between the first inner magnetic pole and the upper end face of the first annular cavity, and Φ 内1下 is the magnetic flux between the first inner magnetic pole and the lower end face of the first annular cavity. The second inner magnetic pole and the third outer magnetic pole and the fourth outer magnetic pole surrounding the second annular cavity satisfy: ∑(Φ3, Φ4) ≤ Φ 内2上 +Φ 内2下 ; where Φ3 and Φ4 are the magnetic fluxes of the third outer magnetic pole and the fourth outer magnetic pole heads respectively; Φ 内2上 is the magnetic flux between the second inner magnetic pole and the upper end face of the second annular cavity, and Φ 内2下 is the magnetic flux between the first inner magnetic pole and the lower end face of the first annular cavity. This is because the orientation magnetic field is closed. If this condition is not satisfied, resulting in the total magnetic flux of all outer magnetic pole heads being greater than the total magnetic flux between the inner magnetic pole and the upper and lower planes of the annular cavity, it will cause a large amount of magnetic leakage, which will not only reduce the orientation degree of the magnetic powder in the annular cavity but also cause energy waste of the current forming the orientation magnetic field. The magnetic fluxes of the inner and outer magnetic poles can be adjusted by changing the current magnitudes in the inner magnetic pole and / or each outer magnetic pole.

[0050] The first die sleeve and the second die sleeve are annular and are respectively arranged around the first annular die cavity and the second annular die cavity. The first die sleeve and the first annular die cavity are in the same plane, and the second die sleeve and the second annular die cavity are in the same plane. The first die sleeve, the first annular die cavity and the magnetic conduction core rod of the first inner magnetic pole are coaxial, and the second die sleeve, the second annular die cavity and the magnetic conduction core rod of the second inner magnetic pole are coaxial. The magnetic conduction core rod of the first inner magnetic pole is perpendicular to the plane where the first die sleeve and the first annular die cavity are located. One end of the magnetic conduction core rod is coplanar with the lower end surfaces of the first die sleeve and the first annular die cavity, and the other end of the magnetic conduction core rod is coplanar with the upper end surfaces of the first die sleeve and the first annular die cavity or higher than the upper end surface. The magnetic conduction core rod of the second inner magnetic pole is perpendicular to the plane where the second die sleeve and the second annular die cavity are located. One end of the magnetic conduction core rod is coplanar with the lower end surfaces of the second die sleeve and the second annular die cavity, and the other end of the magnetic conduction core rod is coplanar with the upper end surfaces of the second die sleeve and the second annular die cavity or higher than the upper end surface. The inner diameter of the die sleeve is the same as the outer diameter of the magnetic ring to be prepared, and the wall thickness (outer diameter = inner diameter + wall thickness) is generally required to be ≥10 mm.

[0051] The present invention provides a forming method for a sintered oriented magnetic ring, which is realized by the above-mentioned forming equipment for a sintered oriented magnetic ring and includes the following steps:

[0052] Step 1: Put magnetic powder into the annular die cavity, and introduce the magnetic fields generated by the coils with current passing through and soft magnetic materials into multiple outer magnetic poles surrounding the annular die cavity respectively through magnetic conduction pole heads, and introduce them into the corresponding inner magnetic poles respectively through magnetic conduction core rods, so as to form multiple orientation magnetic fields between the inner magnetic poles and the outer magnetic poles.

[0053] Step 2: Drive the die sleeve, the pressing head, the magnetic conduction core rod of the inner magnetic pole and the magnetic powder of a single forming unit to rotate coaxially simultaneously through a servo motor respectively to complete the magnetization and orientation of the magnetic powder in the corresponding annular die cavity. During the orientation process, the upper pressing head and the lower pressing head of the pressing head move towards each other or in the same direction while rotating, and apply a gradually increasing pressure to the magnetic powder to complete the pressing and forming of the magnetic powder.

[0054] Currently, the preparation of radially magnetized rings generally adopts two methods. One is to generate a radiation orientation magnetic field by using the principle of like poles repelling each other. When the inner diameter of the radially magnetized ring is small, the intensity of the orientation magnetic field obtained by this method is low, and the magnetic powder orientation is incomplete. At the same time, for magnetized rings with a large length-diameter ratio, the uniformity in the axial direction is poor. The other is to introduce the two poles of the magnetic field into the inner-outer poles or outer-outer poles respectively through a magnetic conduction device, and then obtain the magnetized ring through the rotational orientation of the magnetic powder and the magnetic field. Due to the long magnetic path, the leakage magnetic effect results in a low intensity of the orientation magnetic field. In addition, the orientation magnetic field only occupies a very small part of the 360° angle of the circular ring. Therefore, the magnetic powder needs to complete a relative movement of more than 360° with the orientation field to achieve the complete orientation of the entire magnetized ring. When using a single outer pole for orientation, there are differences in the orientation difficulty at different positions on the circumference of the magnetized ring, which further makes the orientation of the magnetized ring uneven in the circumferential direction. When using multiple outer poles for orientation, the polarities of different outer poles are opposite. During the relative rotational movement of the magnetic powder and the orientation magnetic field, the magnetic powder will be repeatedly subjected to the action of suction and repulsion forces, not only greatly reducing the orientation degree of the magnetized ring, but also significantly reducing the orientation uniformity of the magnetized ring in the circumferential direction.

[0055] The forming method of the present invention can simultaneously form at least two radially oriented magnetized rings. Multiple high-intensity orientation magnetic fields are used to rotate and orient the magnetized rings. When the magnetized ring rotates one week, the magnetized ring in each annular film cavity completes multiple magnetic field orientations, and each orientation magnetic field is independently provided by a coil with current passing through and a soft magnetic material, effectively suppressing the reduction of the magnetic field caused by the leakage magnetic problem in the single-coil plus yoke iron magnetic conduction mode. In the method of the present invention, the magnetic powder is magnetized by multiple orientation magnetic fields during the rotational orientation process, effectively reducing the state difference of the magnetic powder in the circumferential direction during the orientation forming process, and ensuring a high value of the orientation magnetic field, greatly improving the orientation degree of the magnetic powder in the circumferential direction, enhancing the orientation uniformity, and also significantly improving the surface field consistency at different positions in the circumferential direction of the magnetized ring. Exemplarily, when the present invention simultaneously manufactures two radially oriented magnetized rings, 5 high-intensity orientation magnetic fields are used to rotate and orient the magnetized rings. When the magnetized ring rotates one week, the magnetized ring in the first annular film cavity completes 3 magnetic field orientations, and the magnetized ring in the second annular film cavity completes 2 magnetic field orientations.

[0056] During the forming process, corresponding inner magnetic poles and outer magnetic poles form multiple orientation magnetic fields. The intensity of each orientation magnetic field can be the same or different, but all must be ≥ 1.2 T to ensure the orientation degree of the magnetic field and enable the magnetic ring to be fully oriented. Exemplarily, during the forming process of simultaneously manufacturing 2 radially oriented magnetic rings, 5 orientation magnetic fields are formed by 2 inner magnetic poles and 4 outer magnetic poles. In the present invention, the orientation magnetic field is generated by an energized coil and soft magnetic material. The orientation magnetic field does not exist all the time, but is turned on by controlling the switch of the current. The intensity of each orientation magnetic field remains unchanged during the forming process of the magnetic ring and is controlled by the magnitude of the passing current. The polarities of multiple outer magnetic poles around the same annular cavity are the same. During the relative rotational movement of the magnetic powder and the orientation magnetic field, the magnetic powder will not be repeatedly affected by suction and repulsion forces, and the magnetic ring can be oriented 360°. The orientation uniformity of the magnetic ring in the circumferential direction is greatly increased.

[0057] During the forming process, the lower punch of the punch that is matched with a single forming unit is flush with the lower end face of the corresponding die sleeve. Magnetic powder is added into each annular cavity. The amount of magnetic powder added is related to the size requirements of the magnetic ring. Generally, it is about the volume of the finished magnetic ring * 7.5 (density). The upper punch of the corresponding punch is pressed down a certain distance to the top of the corresponding magnetic powder. The orientation magnetic field and the corresponding servo motor are turned on. The servo motor simultaneously drives the corresponding die sleeve, punch, magnetic conduction core rod of the inner magnetic pole, and magnetic powder to rotate coaxially to complete the magnetization and orientation of the magnetic powder in the corresponding annular cavity; the magnetic powder in the annular cavity sequentially enters multiple orientation magnetic fields for magnetic field orientation forming. Each time the magnetic powder in the corresponding annular cavity rotates one week, it obtains multiple orientation pressings of the magnetic field. During the orientation process, the upper punch and the lower punch of the punch move towards each other or in the same direction while rotating, applying a gradually increasing pressure to the magnetic powder until the expected density is reached, and the forming process is completed. The rotational speed range of the servo motor is 50 - 500 r / min. During the pressing and forming process, the speed of the upper and lower punches moving towards each other or in the same direction is 30 m / s - 70 m / s. As the density of the magnetic powder gradually increases, the frictional force between the magnetic powders gradually increases, and the pressure applied by the upper and lower punches to the magnetic powder gradually increases.

[0058] The device of the present invention has at least two inner magnetic poles and four outer magnetic poles. Each orientation magnetic pole is individually provided by an energized coil and soft magnetic material, which can ensure a high value of the orientation magnetic field, thereby improving the orientation degree of the magnetic ring during the forming process; the polar heads of the outer magnetic poles around the same annular cavity have the same polarity, ensuring that during the relative rotational movement of the magnetic powder and the orientation magnetic field, the magnetic powder is always affected by the suction force, improving the orientation degree of the magnetic ring and the orientation uniformity of the magnetic ring in the circumferential direction of the annular cavity, and avoiding the problem in the prior art that when the polarities of the outer magnetic poles are opposite and the magnetic powder and the orientation magnetic field rotate relative to each other, the magnetic powder will be repeatedly affected by suction and repulsion forces, not only greatly reducing the orientation degree of the magnetic ring, but also greatly reducing the orientation uniformity of the magnetic ring in the circumferential direction.

[0059] When manufacturing a radially oriented magnetic ring using the forming method of the present invention, multiple high-intensity orientation magnetic fields are used to rotate and orient the magnetic ring. For every rotation of the magnetic powder in the first annular mold cavity, it undergoes orientation pressing by the magnetic field three times, and for every rotation of the magnetic powder in the second annular mold cavity, it undergoes orientation pressing by the magnetic field twice. Moreover, each orientation magnetic field is independently provided by a coil with current passing through and a soft magnetic material, effectively suppressing the reduction of the magnetic field caused by the magnetic leakage problem in the single-coil plus yoke iron magnetic conduction mode. The present invention simultaneously completes the orientation forming of the magnetic powder through two parallel annular mold cavities, and improves the efficiency of the magnetic powder orientation forming through the simultaneous orientation of multiple inner magnetic poles and outer magnetic poles. Two magnetic rings can be formed simultaneously. Compared with the magnetic rings formed by the existing method, it has a higher surface field, a lower surface field peak deviation, indicating a higher surface field consistency.

[0060] Embodiment

[0061] The size of the magnetic ring 1 to be formed in this embodiment is Ф40*Ф10*30mm; the size of the magnetic ring 2 is Ф50*Ф8*20mm. Figure 1 The following shows the schematic diagram of the forming of a dual-mold cavity magnetic field rotationally oriented radiation magnetic ring in this embodiment. The forming process includes the following steps:

[0062] Put 265g and 287g of magnetic powder into the first annular mold cavity and the second annular mold cavity respectively;

[0063] Set a first inner magnetic pole at the center of the first annular mold cavity. The diameter d1 of the magnetic conduction core rod of the first inner magnetic pole is 11.5mm; set 3 outer magnetic poles on the circumference, namely the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole. The 3 outer magnetic poles are evenly distributed along the circumferential direction of the mold sleeve, and the included angle between each two outer magnetic poles is 120°. The widths W1, W2, and W3 of the pole heads of the three outer magnetic poles are all 1mm, forming 3 orientation magnetic fields with intensities of 1.3T, 1.5T, and 1.0T respectively; the sum of the widths of the pole heads of the outer magnetic poles is 3mm, satisfying ∑(W1, W2, W3) ≤ 1 / 2(d1*π). The magnetic fluxes Φ1, Φ2, and Φ3 of the pole heads of the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole are respectively: 45.5μWb, 52.5μWb, and 36μWb. The magnetic flux Φ between the first inner magnetic pole and the upper end face of the first annular mold cavity 内1上 is 103.8μWb, and the magnetic flux Φ between the first inner magnetic pole and the lower end face of the first annular mold cavity 内1下 is 103.8μWb, satisfying ∑(Φ1, Φ2, Φ3) ≤ Φ 内1上 +Φ 内1下 .

[0064] A second inner magnetic pole is set at the center of the second annular cavity. The diameter d2 of the magnetic core rod of the second inner magnetic pole is 9.2 mm. There are 2 outer magnetic poles arranged on the circumference, namely the first outer magnetic pole and the fourth outer magnetic pole. The pole head width of the first outer magnetic pole is 1 mm, and the pole head width of the fourth outer magnetic pole is 2 mm. Along the counterclockwise direction of the first outer magnetic pole, the included angle between the first outer magnetic pole and the fourth outer magnetic pole is 160°, forming 2 orientation magnetic fields with an intensity of 1.8 T each. The sum of the pole head widths of the outer magnetic poles is 3 mm, satisfying ∑(W3, W4) ≤ 1 / 2(d2*π). The magnetic flux Φ3 of the pole head of the third outer magnetic pole is 36 μWb, and the magnetic flux Φ4 of the pole head of the fourth outer magnetic pole is 72 μWb. The magnetic flux Φ 内2上 between the second inner magnetic pole and the upper end face of the second annular cavity is 66.5 μWb, and the magnetic flux Φ 内2下 between the first inner magnetic pole and the lower end face of the first annular cavity is 66.5 μWb, satisfying ∑(Φ3, Φ4) ≤ Φ 内2上 +Φ 内2下 .

[0065] During the orientation process, the current switch is turned on. The magnetic field generated by the current-carrying coil and the soft magnetic material is introduced into the 4 outer magnetic poles and 2 inner magnetic poles through the pole heads of the magnetic conductors and the magnetic core rods. Among them, the pole heads of the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole on the circumference of the first annular cavity are all S poles, and the pole head of the first inner magnetic pole is an N pole. The pole heads of the first outer magnetic pole and the fourth outer magnetic pole on the circumference of the second annular cavity are both N poles, and the pole head of the second inner magnetic pole is an S pole.

[0066] The magnetic powder in the first annular cavity passes through 3 orientation magnetic fields, and the magnetic powder in the second annular cavity passes through 2 orientation magnetic fields, obtaining sufficient pre-magnetization and orientation first. Then, the first servo motor and the second servo motor are started, and the servo motors drive the mold, the pressure head, the magnetic core rod, and the magnetic powder to rotate coaxially to complete the full magnetization and orientation of the magnetic powder in the cavity. The rotation speeds of the first servo motor and the second servo motor are 100 r / min and 200 r / min respectively.

[0067] During the orientation process, through the opposite or same-direction movement of the upper and lower pressure heads with a speed of 30 m / s - 70 m / s, pressure is applied to the magnetic powder, and the applied pressure gradually increases until the expected density is reached to complete the forming process.

[0068] Comparative Example 1

[0069] The sizes of the magnetic rings 1 to be formed in this embodiment are Ф40*Ф10*30 mm; the sizes of the magnetic rings 2 are Ф50*Ф8*20 mm. Figure 1 The following shows the schematic diagram of the magnetic ring forming by the magnetic field rotation orientation of the double cavity in this embodiment. The forming process includes the following steps:

[0070] Put 265 g and 287 g of magnetic powder into the first annular cavity and the second annular cavity respectively;

[0071] A first inner magnetic pole is arranged at the center of the first annular cavity. The diameter d1 of the magnetic conduction core rod of the first inner magnetic pole is 11.5 mm. Three outer magnetic poles are arranged on the circumference, namely the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole. The three outer magnetic poles are evenly distributed along the circumferential direction of the die sleeve, and the included angle between each two outer magnetic poles is 120°. The widths W1, W2, and W3 of the pole heads of the three outer magnetic poles are all 6.5 mm, forming three orientation magnetic fields with intensities of 0.8 T, 0.8 T, and 0.62 T respectively. The sum of the widths of the pole heads of the outer magnetic poles is 19.5 mm, which does not satisfy ∑(W1, W2, W3) ≤ 1 / 2(d1*π). The magnetic fluxes Φ1, Φ2, and Φ3 of the pole heads of the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole are respectively: 182 μWb, 182 μWb, and 141 μWb. The magnetic flux Φ 内1上 between the first inner magnetic pole and the upper end face of the first annular cavity is 103.8 μWb, and the magnetic flux Φ 内1下 between the first inner magnetic pole and the lower end face of the first annular cavity is 103.8 μWb, which does not satisfy ∑(Φ1, Φ2, Φ3) ≤ Φ 内1上 +Φ 内1下 .

[0072] A second inner magnetic pole is arranged at the center of the second annular cavity. The diameter d2 of the magnetic conduction core rod of the second inner magnetic pole is 9.2 mm. Two outer magnetic poles are arranged on the circumference, namely the first outer magnetic pole and the fourth outer magnetic pole. The width of the pole head of the first outer magnetic pole is 7 mm, and the width of the pole head of the fourth outer magnetic pole is 8 mm. Along the counterclockwise direction of the first outer magnetic pole, the included angle between the first outer magnetic pole and the fourth outer magnetic pole is 160°, forming two orientation magnetic fields with intensities of 1 T each. The sum of the widths of the pole heads of the outer magnetic poles is 15 mm, which does not satisfy ∑(W3, W4) ≤ 1 / 2(d2*π). The magnetic flux Φ3 of the pole head of the third outer magnetic pole is 141 μWb, and the magnetic flux Φ4 of the pole head of the fourth outer magnetic pole is 160 μWb. The magnetic flux Φ 内2上 between the second inner magnetic pole and the upper end face of the second annular cavity is 132.9 μWb, and the magnetic flux Φ 内2下 between the first inner magnetic pole and the lower end face of the first annular cavity is 132.9 μWb, which does not satisfy ∑(Φ3, Φ4) ≤ Φ 内2上 +Φ 内2下 .

[0073] During the orientation process, the current switch is turned on, and the magnetic field generated by the current-carrying coil and the soft magnetic material is introduced into the four outer magnetic poles and the two inner magnetic poles through the magnetic pole heads and the magnetic conduction core rods. Among them, the pole heads of the first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole on the circumference of the first annular cavity are all S poles, and the pole head of the first inner magnetic pole is an N pole. The pole heads of the first outer magnetic pole and the fourth outer magnetic pole on the circumference of the second annular cavity are both N poles, and the pole head of the second inner magnetic pole is an S pole.

[0074] In the first annular film cavity, the magnetic powder passes through three orientation magnetic fields, and in the second annular film cavity, the magnetic powder passes through two orientation magnetic fields. First, sufficient pre-magnetization and orientation are obtained. Then, the first servo motor and the second servo motor are started, and the servo motors drive the mold, the pressure head, the magnetic core rod, and the magnetic powder to rotate coaxially to complete the sufficient magnetization and orientation of the magnetic powder in the film cavity. The rotational speeds of the first servo motor and the second servo motor are 100 r / min and 200 r / min respectively.

[0075] During the orientation process, through the opposite or same-direction movement of the upper and lower pressure heads at a speed of 30 m / s - 70 m / s, pressure is applied to the magnetic powder, and the applied pressure gradually increases until the expected density is reached to complete the forming process.

[0076] Comparative Example 2

[0077] The size of the magnetic ring to be formed in the comparative example is Ф50*Ф8*20 mm. The forming process includes the following steps:

[0078] Put 287 g of magnetic powder into the annular mold cavity;

[0079] The inner magnetic pole has a diameter of 9.2 mm at the center of the annular mold cavity, and two outer magnetic poles are arranged on the circumference, namely the first outer magnetic pole and the second outer magnetic pole. The first outer magnetic pole is an N pole with a pole head width of 1 mm, and the second outer magnetic pole is an S pole with a pole head width of 2 mm. Along the counterclockwise direction of the first outer magnetic pole, the included angle between the first outer magnetic pole and the second outer magnetic pole is 160°, forming two orientation magnetic fields with intensities of 1.8 T and 1.6 T respectively.

[0080] During the orientation process, the current switch is turned on, and the magnetic field generated by the current-carrying coil and the soft magnetic material is introduced into the outer magnetic poles through the magnetic pole head and the magnetic core rod. Among them, a magnetic field with an inward magnetic field direction and a magnetic field intensity of 1.8 T is generated between the first outer magnetic pole and the inner magnetic pole, and a magnetic field with an outward magnetic field direction and a magnetic field intensity of 1.6 T is generated between the second outer magnetic pole and the inner magnetic pole.

[0081] Sufficient pre-magnetization and orientation are obtained. Then, the servo motor is started, and the servo motor drives the mold, the pressure head, the magnetic core rod, and the magnetic powder to rotate coaxially to complete the sufficient magnetization and orientation of the magnetic powder in the film cavity. The rotational speed of the servo motor is 200 r / min.

[0082] During the orientation process, through the opposite or same-direction movement of the upper and lower pressure heads at a speed of 30 m / s - 70 m / s, pressure is applied to the magnetic powder, and the applied pressure gradually increases until the expected density is reached to complete the forming process.

[0083] After overall magnetization, the surface field performance test of the magnetic ring is shown in Table 1. It can be found that by using the device and method of the present invention, two magnetic rings with different sizes and different performances can be prepared at one time, the preparation efficiency is greatly improved, and the prepared magnetic rings have a higher surface field and a lower surface field peak deviation, indicating that the surface field consistency of the method of the present invention is relatively high. When preparing magnetic rings of the same size (Ф50*Ф8*20mm), since the polarities of the two outer magnetic poles at the ends close to the annular cavity are opposite in Comparative Example 2, during the relative rotational movement of the magnetic powder and the orientation magnetic field, the magnetic powder is repeatedly affected by the suction and repulsion forces, and the orientation degree of the magnetic ring is greatly reduced, resulting in the surface field peak of the magnetic ring being much lower than that of the magnetic ring prepared by the present invention. In Comparative Example 1, since the size and magnetic flux of the outer magnetic pole head do not meet the requirements of the present invention, the orientation magnetic field is dispersed and magnetic leakage occurs, and the orientation degree of the magnetic ring is low, resulting in a low surface field peak of the magnetic ring.

[0084] Table 1 Surface Field Performance Test of Magnetic Rings in Examples and Comparative Examples

[0085] Sample Magnetic Field Peak (Gs) Peak Deviation (%) Magnetic Ring of Example 1 3120 1.7 Magnetic Ring of Example 2 3650 2.5 Magnetic Ring 1 of Comparative Example 1 2651 2.7 Magnetic Ring 2 of Comparative Example 1 2700 3.6 Magnetic Ring of Comparative Example 2 2760 22

[0086] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A forming device for a sintered radiation-oriented magnetic ring, characterized in that, It includes a forming unit composed of an inner magnetic pole, an annular cavity, a die sleeve, and an outer magnetic pole arranged from the inside out; The number of the forming units is more than 2. The annular cavities of different forming units are arranged in parallel. The pole heads at one end of the outer magnetic poles surrounding the same annular cavity have the same polarity and are opposite to the polarity of the corresponding inner magnetic poles; The device includes a first die sleeve, a second die sleeve, a first annular cavity, a second annular cavity, a first inner magnetic pole, a second inner magnetic pole, a first outer magnetic pole, a second outer magnetic pole, a third outer magnetic pole, and a fourth outer magnetic pole; The first inner magnetic pole and the second inner magnetic pole are respectively composed of a coil through which current passes, soft magnetic material, and a magnetic conduction mandrel. The first inner magnetic pole and the second inner magnetic pole have opposite polarities; The first outer magnetic pole, the second outer magnetic pole, the third outer magnetic pole, and the fourth outer magnetic pole are all composed of a coil through which current passes, soft magnetic material, and a pole head. The first inner magnetic pole and the second inner magnetic pole share the third outer magnetic pole; The first outer magnetic pole, the second outer magnetic pole, and the third outer magnetic pole are evenly distributed on the 360° circumference around the first annular cavity. The included angle between adjacent outer magnetic poles is 120°. The pole heads of the three outer magnetic poles close to the first annular cavity have the same polarity and are opposite to the polarity of the first inner magnetic pole; The third outer magnetic pole and the fourth outer magnetic pole are unevenly distributed on the 360° circumference around the second annular cavity. Along the counterclockwise direction of the third outer magnetic pole, the included angle between the third outer magnetic pole and the fourth outer magnetic pole is 160°. The pole heads of the two outer magnetic poles close to the second annular cavity have the same polarity and are opposite to the polarity of the second inner magnetic pole.

2. The molding device according to claim 1, wherein Each inner magnetic pole is respectively composed of a coil through which current passes, soft magnetic material, and a magnetic conduction mandrel. The adjacent inner magnetic poles have opposite polarities, and the adjacent inner magnetic poles share at least one outer magnetic pole.

3. The molding device according to claim 1, characterized in that, The number of the outer magnetic poles of the forming unit is N, N≥4. Each outer magnetic pole is composed of a coil through which current passes, soft magnetic material, and a pole head. The outer magnetic poles are evenly or unevenly distributed on the 360° circumference around the annular cavity. The number of outer magnetic poles around each annular cavity is a, b, c…n respectively, satisfying ∑(a, b, c…n)=N.

4. The molding device according to claim 1, characterized in that, The sum of the widths of the pole tips of the outer magnetic poles around the same annular cavity is W, and the diameter of the magnetic core rod of the corresponding inner magnetic pole is d, satisfying W ≤ ½ , where the units of W and d are mm.

5. The shaping device according to claim 1, characterized in that, The sum of the pole head magnetic fluxes of the outer magnetic poles around the same annular cavity is , and the sum of the magnetic fluxes of the corresponding inner magnetic poles and the upper end face of the annular cavity is , and the sum of the magnetic fluxes of the corresponding inner magnetic poles and the lower end face of the annular cavity is , satisfying .

6. The molding device according to claim 1, characterized in that The first annular cavity and the second annular cavity are arranged in parallel. The first annular cavity is located between the first inner magnetic pole and the first die sleeve. The second annular cavity is located between the second inner magnetic pole and the second die sleeve; Connecting the midpoints of the end faces of the pole heads of several outer magnetic poles surrounding the same annular cavity with lines can form a circle, and the center of this circle coincides with the center of the annular cavity it surrounds.

7. The molding device according to claim 1, wherein, The first die sleeve and the second die sleeve are annular and are respectively arranged around the first annular cavity and the second annular cavity. The first die sleeve and the first annular cavity are in the same plane, and the second die sleeve and the second annular cavity are in the same plane; The magnetic conduction mandrels of the first die sleeve, the first annular cavity, and the first inner magnetic pole are coaxial. The magnetic conduction mandrels of the second die sleeve, the second annular cavity, and the second inner magnetic pole are coaxial; The magnetic conduction mandrel of the first inner magnetic pole is perpendicular to the plane where the first die sleeve and the first annular cavity are located. One end of the magnetic conduction mandrel is coplanar with the lower end faces of the first die sleeve and the first annular cavity, and the other end of the magnetic conduction mandrel is coplanar with the upper end faces of the first die sleeve and the first annular cavity or higher than the upper end face; The magnetic conduction mandrel of the second inner magnetic pole is perpendicular to the plane where the second die sleeve and the second annular die cavity are located. One end of the magnetic conduction mandrel is coplanar with the lower end surface of the second die sleeve and the second annular die cavity, and the other end of the magnetic conduction mandrel is coplanar with the upper end surface of the second die sleeve and the second annular die cavity or higher than the upper end surface.

8. A forming method of a sintered oriented magnetic ring, realized by the forming device according to any one of claims 1 to 7, comprising the following steps: Step 1: Put magnetic powder into the annular die cavity, and introduce the magnetic fields generated by the coils with current passing through and soft magnetic materials into multiple outer magnetic poles surrounding the annular die cavity through magnetic conduction pole heads respectively, and introduce them into the corresponding inner magnetic poles through magnetic conduction mandrels respectively, so as to form multiple orientation magnetic fields between the inner magnetic poles and the outer magnetic poles; Step 2: Drive the die sleeve, the pressure head, the magnetic conduction mandrel of the inner magnetic pole and the magnetic powder of a single forming unit to rotate coaxially simultaneously through a servo motor, so as to complete the magnetization and orientation of the magnetic powder in the corresponding annular die cavity; during the orientation process, the upper pressure head and the lower pressure head of the pressure head move towards each other or in the same direction while rotating, and apply gradually increasing pressure to the magnetic powder to complete the pressing and forming of the magnetic powder.

9. The molding method according to claim 8, wherein The intensity of the orientation magnetic field ≥ 1.2T, and / or the rotation speed of the servo motor is 50 - 500 r / min.

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