Permanent magnet

Abstract

This improves work efficiency by fixing permanent magnets to a core metal without using adhesive. [Solution] A method for manufacturing a permanent magnet includes at least a magnetized object forming step of forming a magnetized object by applying a predetermined pressure to magnet powder and thermosetting resin, and a heating step of magnetizing the magnet powder by heating it to a point above the Curie point while the permanent magnet of the field section is brought close to the magnetized object placed on a base member, and fixing the magnetized object to the base member by melting and hardening the thermosetting resin.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a permanent magnet and a permanent magnet.

Background Art

[0002] Conventionally, a magnetic encoder used for position detection of a rotating device is known. When using a compression-molded bonded magnet as the magnet for the magnetic encoder, first, after mixing magnet powder and a thermosetting resin, the magnet powder and the thermosetting resin are heated to a predetermined temperature to cure the thermosetting resin.

[0003] Next, the magnet powder is magnetized to produce a permanent magnet. After that, an adhesive of the thermosetting resin is applied to the permanent magnet or a holder serving as a core metal, and the adhesive is heated to fix the permanent magnet to the holder, thereby manufacturing the magnet for the magnetic encoder. That is, in this method for manufacturing the magnet for the magnetic encoder, two thermosetting steps are required.

[0004] For example, in Patent Document 1, a rare-earth bonded magnet in which magnet powder made of rare earth is bonded with a binder made of an epoxy resin is used, and it is described that after fitting the magnet into a holder, the two are joined with an adhesive of an epoxy resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The above-described method for manufacturing a permanent magnet requires two thermosetting steps. However, since the thermosetting step requires a lot of time, there is room for further improvement in the above manufacturing method from the viewpoint of improving work efficiency.

[0007] In view of the above problems, the present invention aims to provide a method for manufacturing permanent magnets that can improve work efficiency by fixing the permanent magnet to a core metal without using an adhesive. [Means for solving the problem]

[0008] To achieve the above objective, the method for manufacturing a permanent magnet according to the present invention includes at least a magnetized object forming step of forming a magnetized object by applying a predetermined pressure to magnet powder and thermosetting resin, and a heating step of magnetizing the magnet powder by heating it to a point above the Curie point while the permanent magnet of the field section is brought close to the magnetized object placed on a base member, and fixing the magnetized object to the base member by melting and curing the thermosetting resin. [Effects of the Invention]

[0009] The method for manufacturing permanent magnets according to the present invention can improve work efficiency by fixing the permanent magnet to a core metal without using an adhesive. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view showing a schematic configuration example of a magnetization device used in a method for manufacturing a permanent magnet according to the embodiment. [Figure 2] Figure 2 is a cross-sectional view showing a part of the process for forming a magnetized object according to the embodiment. [Figure 3] Figure 3 is a cross-sectional view showing a part of the process for forming a magnetized object according to the embodiment. [Figure 4] Figure 4 is a perspective view of the magnetized object formed by the magnetized object formation process according to the embodiment. [Figure 5] Figure 5 is a perspective view showing the state after the mounting process according to the embodiment, with the object to be magnetized placed on the base member. [Figure 6] Figure 6 is a cross-sectional view showing the state after the mounting process according to the embodiment, with the object to be magnetized placed on the base member. [Figure 7]Figure 7 is an exploded perspective view showing the relationship between the field section, the magnetized section, and the base member in the axial direction during the heating process according to the embodiment. [Figure 8] Figure 8 is a perspective view showing the field section, the section to be magnetized, and the base member in the heating process according to the embodiment. [Figure 9] Figure 9 is a cross-sectional view showing the heating process of the magnetization device according to the embodiment. [Figure 10] Figure 10 is a cross-sectional view showing the cooling process of the magnetization device according to the embodiment. [Figure 11] Figure 11 is a perspective view showing an object to be magnetized after being magnetized by the magnetization device according to the embodiment. [Modes for carrying out the invention]

[0011] The method for manufacturing a permanent magnet and the permanent magnet itself, according to the embodiment, will be described below with reference to the drawings. However, this embodiment does not limit the present invention. Furthermore, the dimensional relationships and ratios of the elements in the drawings may differ from reality. Even between drawings, there may be differences in dimensional relationships and ratios. Also, the contents described in one embodiment or modification generally apply to other embodiments and modifications.

[0012] [Embodiment] First, an example of the magnetization device 1 used in the method for manufacturing a permanent magnet according to an embodiment will be described. FIG. 1 is a cross-sectional view showing a schematic configuration example of the magnetization device 1 used in the method for manufacturing a permanent magnet according to an embodiment. FIG. 2 is a cross-sectional view showing a part of the magnetized object forming step according to the embodiment. FIG. 3 is a cross-sectional view showing a part of the magnetized object forming step according to the embodiment. FIG. 4 is a perspective view of the magnetized object 100 formed by the magnetized object forming step according to the embodiment. FIG. 5 is a perspective view showing a state in which the magnetized object 100 is disposed on the base member 110 after the placing step according to the embodiment. FIG. 6 is a cross-sectional view showing a state in which the magnetized object 100 is disposed on the base member 110 after the placing step according to the embodiment. FIG. 7 is an exploded perspective view showing the relationship among the excitation magnetic field portion 6, the magnetized object 100, and the base member 110 in the axial direction in the heating step according to the embodiment. FIG. 8 is a perspective view showing the excitation magnetic field portion 6, the magnetized object 100, and the base member 110 in the heating step according to the embodiment. FIG. 9 is a cross-sectional view showing the heating step of the magnetization device 1 according to the embodiment. FIG. 10 is a cross-sectional view showing the cooling step of the magnetization device 1 according to the embodiment. FIG. 11 is a perspective view showing the magnetized object 100 after magnetization formed by the magnetization device 1 according to the embodiment. Here, the X direction in each figure is the radial direction of the magnetized object 100 in the present embodiment. The Z direction is the axial direction of the magnetized object 100, which is the vertical direction, the Z1 direction is the upward direction, and the Z2 direction is the downward direction.

[0013] As shown in FIG. 1, the magnetization device 1 used in the method for manufacturing a permanent magnet according to the embodiment magnetizes the magnetized object 100 to manufacture the magnetized object 100' after magnetization. The magnetization device 1 includes a gantry portion 2, a moving portion 3, a heating portion 4, a preheating portion 5, an excitation magnetic field portion 6, a positioning pin 7, a cooling portion 8, and a control portion 10.

[0014] The gantry portion 2 is the base of the magnetization device 1, and at least the moving portion 3, the heating portion 4, the preheating portion 5, the excitation magnetic field portion 6, the positioning pin 7, the cooling portion 8, and the control portion 10 are mounted thereon.

[0015] The moving part 3 relatively moves the adherent magnet 100 and the heating part 4 between a non-heating position and a heating position in the axial direction. The moving part 3 shown in FIG. 1 includes a ceiling plate 31, an actuator 32, and a heating part mounting base 33. The ceiling plate 31 is arranged at a distance from the gantry part 2 in the axial direction, and the actuator 32 and the heating part mounting base 33 are fixed thereto. The actuator 32 relatively moves the ceiling plate 31 in the axial direction with respect to the gantry part 2. The actuator 32 is a linear motion mechanism such as a hydraulic cylinder, for example, and is supplied with power by external power (not shown) and is driven and controlled by the control part 10. A plurality of actuators 32 are arranged between the gantry part 2 and the ceiling plate 31, and for example, four actuators are arranged. The heating part mounting base 33 is for fixing the heating part 4 and is fixed to the downward side surface of the ceiling plate 31.

[0016] The heating part 4 performs magnetization heating on the adherent magnet 100. The heating part 4 is made of a non-magnetic metal material, such as non-magnetic stainless steel, etc., and heats the adherent magnet 100 to a temperature above the Curie point of the magnetic powder constituting the adherent magnet 100. The heating part 4 in the present embodiment is formed in a disc shape, and of the two surfaces in the vertical direction, the upward side surface is fixed to the heating part mounting base 33 of the moving part 3, and the downward side surface is the heating surface 4a. The heating surface 4a is formed with an outer diameter larger than the outer shape of the exciting part 6, and the outer shape is formed larger than the outer diameter of the adherent magnet 100. Also, the heating surface 4a always faces and contacts the upward side surface of the exciting part 6 in the vertical direction (axial direction). The heating part 4 has one or more heaters, and is supplied with power by external power (not shown) and is temperature-controlled by the control part 10.

[0017] The preheating part 5 performs preliminary heating on the adherent magnet 100. The preheating part 5 is made of a non-magnetic metal material, and heats the adherent magnet 100 to a temperature below the Curie point (a temperature higher than room temperature) of the magnetic powder constituting the adherent magnet 100 before the heating part 4 reaches the heating position described later. The preheating part 5 in the present embodiment is formed in a columnar shape.

[0018] The preheating unit 5 heats the object to be magnetized 100 placed on the base member 110 via the base member 110. Of the two sides of the preheating unit 5 in the vertical direction, the lower side is fixed to the frame 2, and the upper side is the heating surface 5a. The heating surface 5a is formed to be larger than the outer diameter of the field section 6 and is in contact with the base member 110. The preheating unit 5 is powered by an external power source (not shown) and has one or more heaters, and its temperature is controlled by the control unit 10.

[0019] The field section 6 generates a magnetic field for the object to be magnetized 100. In this embodiment, the field section 6 magnetizes the object to be magnetized 100 in the axial direction and has a main body 61 and a field section permanent magnet (permanent magnet) 63 which is a permanent magnet for magnetization. In this embodiment, for example, the field section 6 has two rows of field section permanent magnets 63 arranged radially, forming a track formed by two rows of magnetization regions 102, which will be described later.

[0020] The main body 61 is made of a non-magnetic metal material and is formed in a cylindrical shape. Of the two sides of the main body 61 in the vertical direction, the upper side is fixed to the heating surface 4a, and as will be described later, when the heating unit 4 is moved to the heating position, the lower side 6a comes into contact with the object to be magnetized 100. In other words, in the magnetization device 1 according to this embodiment, when the heating unit 4 is moved to the heating position, the lower side 6a of the field unit 6 comes into contact with the upper side 100a of the object to be magnetized 100. A positioning pin 7 is attached to the center of the main body 61, projecting downwards.

[0021] The main body 61 has rectangular parallelepiped-shaped field permanent magnets 63 arranged at equal pitches along the circumferential direction. For example, SmCo sintered magnets can be used for the field permanent magnets 63.

[0022] The field permanent magnets 63 are embedded in the lower end of the main body 61 and generate a magnetic field for the object to be magnetized 100, and are formed, for example, in a rectangular parallelepiped shape. When viewed from above, multiple field permanent magnets 63 are arranged at equal intervals in the circumferential direction of concentric circles centered on the center of the main body 61. Multiple recesses are formed radially along the circumferential direction at predetermined intervals in the main body 61, and each of the multiple field permanent magnets 63 is placed in each of the multiple recesses. The field permanent magnets 63 have two magnetic poles (S pole and N pole) on the upper and lower sides, and are embedded in the main body 61 so that the magnetic poles alternate in the circumferential direction. Here, the magnetic pole of the field permanent magnet 63 on the upper side (e.g., S pole) is different from the magnetic pole of the adjacent field permanent magnet 63 on the upper side in the circumferential direction (e.g., N pole), and the magnetic pole on the lower side (e.g., N pole) is different from the magnetic pole of the adjacent field permanent magnet 63 on the lower side in the circumferential direction (e.g., S pole). In Figure 7, the field permanent magnet 63 is embedded in the main body 61 with the lower side surface 6a exposed, but it may also be embedded inside the main body 61 without being exposed on the lower side surface 6a.

[0023] Furthermore, the shape of the field permanent magnet 63 is not limited to a rectangular parallelepiped shape, but can be any shape as long as it can be embedded in the main body 61. For example, the shape of the field permanent magnet 63 may be a sector shape when viewed from above. Also, although the field section 6 shown in Figure 7 is an example in which the field permanent magnet 63 is arranged on each of two concentric circles of different diameters, this embodiment is not limited to this. For example, in this embodiment, a single row of field permanent magnets 63 may be arranged on a circle centered on the axis of the main body 61.

[0024] The positioning pin 7 determines the position of the object to be magnetized 100 relative to the field section 6 in the radial direction, and is inserted into the through hole 100c of the object to be magnetized 100, which will be described later. The positioning pin 7 is fixed to the field section 6.

[0025] The cooling unit 8 cools the object to be magnetized 100, which has been heated by the heating unit 4. In this embodiment, the cooling unit 8 is fixed to the frame unit 2 by a fixing member (not shown) and outputs air towards the object to be magnetized 100. The cooling unit 8 is, for example, an air-cooling fan or a compressor that supplies compressed air, and cools the object to be magnetized 100 after heating by forced air cooling, which has high cooling efficiency, rather than natural air cooling. The cooling unit 8 is powered by an external power source (not shown), and the airflow is controlled by the control unit 10.

[0026] The control unit 10 comprehensively controls each part of the magnetization device 1 and controls the magnetization device 1 in order to magnetize the object to be magnetized 100. More specifically, the control unit 10 controls the moving unit 3, the heating unit 4, the preheating unit 5, and the cooling unit 8.

[0027] The control unit 10 drives and controls the moving unit 3 to move the heating unit 4 and the field unit 6 relative to the object to be magnetized 100 placed on the base member 110 between a non-heated position and a heated position. Here, the non-heated position is a position in the axial direction where the lower side surface 6a of the field unit 6 is separated from the object to be magnetized 100 (non-contact), and where the object to be magnetized 100 is not heated by the heating unit 4 (see Figure 1). On the other hand, the heated position is a position in the axial direction where the field unit 6 is close to the object to be magnetized 100 (in this embodiment, the lower side surface 6a of the field unit 6 is in contact with the object to be magnetized 100), and the object to be magnetized 100 is heated by the heating unit 4 (see Figure 9).

[0028] The control unit 10 controls the temperature of the heating unit 4 to heat it so that the heating temperature is above the Curie point of the magnetic powder constituting the object to be magnetized 100. In this embodiment, the heating unit 4 is heated by the control unit 10 so that the heating temperature at the heating position is above the Curie point of the magnetic powder and below 350°C. The heating temperature is such that deterioration of the magnetic properties of the magnetic powder constituting the object to be magnetized 100 and deterioration of the thermosetting resin, which will be described later, can be suppressed. The heating temperature is below the Curie point of the permanent magnet 63 of the field section. In the magnetization device 1 according to this embodiment, the control unit 10 presses the field section 6 against the object to be magnetized 100 when the field section 6 comes into contact with the object to be magnetized 100 (pressing the field section 6 against the object to be magnetized 100 in the direction of arrow C shown in Figure 8). More specifically, the control unit 10 drives the moving unit 3 so that when the field unit 6 contacts the object to be magnetized 100, the pressing force is such that damage to the object to be magnetized 100 is suppressed. This suppresses damage to the object to be magnetized 100 and ensures uniformity of the contact state between the object to be magnetized 100 and the field unit 6. The control unit 10 also controls the temperature of the preheating unit 5 so that the preheating unit 5 reaches a preheating temperature below the Curie point of the magnetic powder constituting the object to be magnetized 100 before the heating unit 4 reaches the heating position. In this embodiment, the control unit 10 heats the preheating unit 5 so that the temperature is 30°C or less below the Curie point and 150°C or higher before reaching the heating position.

[0029] The control unit 10 then performs a heating process by heating the heating unit 4 to heat the magnet powder to a level above the Curie point of the magnetized object 100. The heating process takes approximately 1 minute. This heating process simultaneously magnetizes the object 100, hardens the object 100, and fixes the object 100 to the base member 110. In other words, the heating process magnetizes the object 100 with the field permanent magnet 63, and the thermosetting resin contained in the object 100 melts and then hardens, fixing the object 100 to the base member 110, and the object 100 becomes a permanent magnet. In particular, during the heating process, the thermosetting resin contained in the object 100 melts and seeps into the base member 110, thus fixing the object 100 to the base member 110. More specifically, in this embodiment, the object to be magnetized 100 is fixed to the base member 110 solely by a hardened thermosetting resin. Subsequently, the control unit 10 moves the heating unit 4 and the field unit 6 upward (in the direction of arrow D shown in Figure 9). Then, the heated object to be magnetized 100 is cooled by controlling the temperature of the cooling unit 8 (see Figure 9).

[0030] Here, the object to be magnetized 100 is formed in a ring shape, as shown in Figure 4, and has an upper side surface 100a and a lower side surface 100b, which are both sides in the vertical direction (axial direction), and a through hole 100c.

[0031] The object to be magnetized 100 is a rare-earth iron-based magnet before magnetization. In this embodiment, for example, it is formed by mixing magnetic powder containing neodymium (Nd-Fe-B), which is a magnetically isotropic rare-earth iron-based magnet, with a thermosetting resin, such as epoxy resin, in a predetermined ratio. The object to be magnetized 100 is not a small object to be magnetized 100, but a so-called large object to be magnetized 100. For example, it is formed in the shape of a ring with an outer diameter of 10 mm or more, preferably with an outer diameter of 15 mm or more to 50 mm or less.

[0032] In this embodiment, the radial size of the through-hole 100c in the object to be magnetized 100 is larger than the radial size of the positioning pin 7. When the heating unit 4 is positioned in the heating position, a gap s1 is formed radially between the inner circumferential surface of the through-hole 100c in the object to be magnetized 100 and the outer circumferential surface of the positioning pin 7 (see Figure 9). Furthermore, in this embodiment, the radial size of the through-hole 100c in the object to be magnetized 100 is larger than the radial size of the positioning hole 110c of the base member 110, which will be described later.

[0033] As shown in Figure 6, the base member 110 has a base member lower portion 110a, a base member flange portion 110b, and a positioning hole portion 110c. The base member 110 is formed of, for example, a non-magnetic metal material and is a so-called core or holder. For example, the base member 110 is made of stainless steel such as SUS304. The base member lower portion 110a is formed in a ring shape with a smaller radial size than the base member flange portion 110b. The base member flange portion 110b is formed projecting radially outward from the upper end of the base member lower portion 110a. The base member flange portion 110b has an upper end portion 110b1 on which the object to be magnetized 100 is placed. The upper end portion 110b1 is located on one side in the vertical direction (axial direction). The upper end portion 110b1 does not project in either the vertical direction. Furthermore, the contact surface of the base member 110 with the object to be magnetized 100 (i.e., the upper end portion 110b1) is preferably rougher in order to improve adhesive strength. For example, the upper end portion 110b1 may be processed to create an anchoring effect, such as knurling.

[0034] Next, the magnetization method for the object to be magnetized 100 by the magnetization device 1 in this embodiment will be described. The control unit 10 first applies a release agent to at least one of the lower side surface 6a of the field section 6 or the upper side surface 100a of the object to be magnetized 100 (application step). The release agent can be, for example, boron nitride or a heat-resistant fluorine-based release agent.

[0035] First, the control unit 10 prepares a mixture 101 containing magnetic powder (for example, rare earth magnetic powder) adjusted to a predetermined particle size and a thermosetting resin (for example, epoxy resin) (mixture formation step). More specifically, the control unit 10 mixes the magnetic powder and the thermosetting resin in a predetermined ratio. For example, Nd-Fe-B type magnetic powder can be used as the rare earth magnetic powder.

[0036] The method for manufacturing a permanent magnet according to this embodiment uses, for example, Nd-Fe-B magnetic powder, which is obtained by melting an Nd-Fe-B magnetic alloy and crushing a thin strip of the Nd-Fe-B magnetic alloy, prepared by an ultra-rapid cooling method, to adjust the particle size to a predetermined size, and an epoxy-based thermosetting resin. For example, the composition involves adding a thermosetting resin at a concentration of 2.5 weight percent of the weight of the magnetic powder to the magnetic powder. Then, as shown in Figure 2, the control unit 10 places the mixture 101 into the cavity 120c of a mold 120, which includes a mold body 121 and a mold moving part 122.

[0037] Next, as shown in Figure 3, the control unit 10 moves the upper mold downward, thereby applying pressure to the mixture 101, which is a mixture of magnetic powder and thermosetting resin in a predetermined ratio, in the upper and lower molds, and forming a magnetized object 100 made of magnetic powder and thermosetting resin, as shown in Figure 3 (magnetized object formation process).

[0038] The method for manufacturing a permanent magnet according to this embodiment involves placing a mixture 101 into the cavity 120c of a mold 120 and applying a predetermined pressure (molding surface pressure of 5 to 10 tons / cm²). 2 The magnetized object 100 is formed by applying pressure to it in a ring shape (in other words, a donut shape). The formed magnetized object 100 is what is known as a green body.

[0039] In this embodiment, the method for manufacturing a permanent magnet, as shown in Figure 2, involves mixing magnetic powder and thermosetting resin in a predetermined ratio to form a mixture 101, which has a thickness T1 in the vertical direction (axial direction) of, for example, 5 mm before applying pressure. On the other hand, the thickness T2 in the vertical direction (axial direction) of the magnetized object 100, shown in Figures 3 and 4, formed by applying pressure, is, for example, 1 to 2 mm.

[0040] Next, as shown in Figures 5, 6, and 7, the control unit 10 places the object to be magnetized 100 on the upper end portion 110b1 of the base member 110. At this time, a guide member (not shown) is used to align the radial position of the object to be magnetized 100 with the base member 110, and the through hole 100c of the object to be magnetized 100 is aligned with the positioning hole portion 110c of the base member 110.

[0041] Next, the control unit 10 places the base member 110, which is placed on the upper end portion 110b1 of the object to be magnetized 100, onto the heating surface 5a. At this time, a guide member (not shown) is used to position the positioning hole portion 110c of the base member 110 and the positioning pin 7, so that the positioning hole portion 110c and the positioning pin 7 face each other in the vertical direction (axial direction).

[0042] Next, the control unit 10 starts heating the heating unit 4 and the preheating unit 5. Here, the control unit 10 heats the heating unit 4 to the heating temperature and the preheating unit 5 to the preheating temperature. Next, the worker moves the heating unit 4 and the field unit 6 shown in Figure 1 downwards (arrow A in the figure) with the through hole 100c of the object to be magnetized 100 facing the positioning pin 7 in the axial direction.

[0043] Next, the control unit 10 drives the moving unit 3 to move the heating unit 4 shown in Figure 7 (arrow B in the same figure). In this embodiment, the control unit 10 moves the heating unit 4 to the heating position relative to the magnetized object 100 after the heating unit 4 has reached a predetermined heating temperature and the object to be magnetized 100 has reached a predetermined preheating temperature in the non-heating position, and starts heating the preheated magnetized object 100 with the lower side surface 6a of the field unit 6 in contact with the upper side surface 100a of the magnetized object 100 (heating process). When the control unit 10 moves the heating unit 4 from the non-heating position to the heating position by the moving unit 3, it terminates heating of the preheating unit 5, i.e., turns off the temperature control. The alignment of the field unit 6 and the base member 110 is performed by a positioning pin 7 attached to the field unit 6 and a positioning hole 110c of the base member 110. Then, during the heating process in which the positioning pin 7 and the positioning hole 110c are engaged, a gap s1 is formed between the inner circumferential surface of the through hole 100c and the outer circumferential surface of the positioning pin 7 (see Figure 9).

[0044] Next, the control unit 10 heats the object to be magnetized 100 until it reaches or exceeds the Curie point, with the lower side surface 6a of the field unit 6 in contact with the object to be magnetized 100. Then, after a predetermined time has elapsed at the heated position, the control unit 10 uses the moving unit 3 to move the heating unit 4 shown in Figure 9 from the heated position to the non-heated position relative to the object to be magnetized 100 (arrow D in the same figure). Here, the predetermined time elapsed refers to a sufficient amount of time for the object to be magnetized 100 to reach or exceed the Curie point.

[0045] Next, as shown in Figure 10, the control unit 10 cools the object to be magnetized 100 with the cooling unit 8 in the non-heated position. Then, in the non-heated position, the control unit 10 terminates the cooling by the cooling unit 8 after a predetermined time has elapsed since the start of cooling by the cooling unit 8. Here, the predetermined time elapsed as described above means a sufficient amount of time for the object to be magnetized 100 to go from above the Curie point to below the Curie point, preferably to Curie point minus 50°C.

[0046] Next, the control unit 10 removes the magnetized object 100'. When the magnetization device 1 is to re-magnetize the object 100, the control unit 10 starts heating the preheating unit 5 because the heating unit 4 is already heated.

[0047] As described above, the magnetization device 1 in this embodiment magnetizes the object to be magnetized 100 by raising its temperature from below the Curie point to above the Curie point, and then lowering its temperature from above the Curie point to below the Curie point while the magnetization magnetic field is applied by the field unit 6. In this way, the magnetization device 1 produces the magnetized object to be magnetized 100' shown in Figure 11 from the object to be magnetized 100. The magnetized object to be magnetized 100' has a magnetized region 102 formed by the permanent magnet 63 of the field unit. The magnetized object to be magnetized 100' in this embodiment is a permanent magnet in which a magnetized region 102 with alternately different magnetic poles is formed along the circumferential direction on its upper surface, and is a permanent magnet with two rows of multi-pole magnetization in a ring shape on at least the upper side surface 100a.

[0048] The magnetized object 100' formed by the manufacturing method according to this embodiment is used in rotating equipment such as motors and encoders. More specifically, the magnetized object 100' is used, for example, in an encoder (magnetic encoder) or a motor (axial gap motor). For example, the magnetized object 100' used in a magnetic encoder is used in a position detection sensor that is provided adjacent to a shaft that rotates around its axis and detects the rotational position of the shaft.

[0049] The method for manufacturing a permanent magnet according to this embodiment includes the following steps. The method for manufacturing a permanent magnet includes a magnetized object forming step of forming a magnetized object 100 by applying a predetermined pressure to magnet powder and thermosetting resin, and a heating step of magnetizing the magnet powder by heating it to a temperature above the Curie point while the magnetized object 100 is placed on a base member 110 and the field permanent magnet 63 is brought close to it, and fixing the magnetized object 100 to the base member 110 by melting and hardening the thermosetting resin. Therefore, according to the method for manufacturing a permanent magnet according to this embodiment, the magnetized powder can be magnetized and the magnetized object 100 can be fixed to the base member 110 by melting and hardening the thermosetting resin in a single heating step. Therefore, according to the method for manufacturing a permanent magnet according to this embodiment, there is no need to perform two heating steps, so the work efficiency during manufacturing can be improved. Moreover, because the method for manufacturing a permanent magnet according to this embodiment has only one heating step, the thermal history of the permanent magnet can be reduced. Furthermore, in the method for manufacturing a permanent magnet according to this embodiment, the object to be magnetized 100 can be fixed to the base member 110 by the cured thermosetting resin, eliminating the need to use a separate adhesive.

[0050] The method for manufacturing a permanent magnet according to this embodiment includes the following steps. The method for manufacturing a permanent magnet according to this embodiment includes a coating step of applying a release agent to at least one of the contact surfaces between the field section 6 and the object to be magnetized 100 before the heating step. Therefore, according to the method for manufacturing a permanent magnet according to this embodiment, it is possible to suppress the adhesion of the object to be magnetized 100 to the field section 6 after the heating step.

[0051] The method for manufacturing a permanent magnet according to this embodiment includes the following steps. In the method for manufacturing a permanent magnet according to this embodiment, the vertical thickness T2 of the object to be magnetized 100 formed in the object to be magnetized step is 1 to 2 mm. Therefore, in the method for manufacturing a permanent magnet according to this embodiment, the vertical thickness T2 of the object to be magnetized 100 is thin, and there is little uncured thermosetting resin after the heating step.

[0052] The method for manufacturing a permanent magnet according to this embodiment includes the following steps. In the heating step in which the positioning pin 7 and the positioning hole 110c are engaged, a gap s1 is formed between the inner circumferential surface of the through hole 100c and the outer circumferential surface of the positioning pin 7. Therefore, the method for manufacturing a permanent magnet according to this embodiment can prevent the thermally expanded positioning pin 7 from pressing against the object to be magnetized 100 during the heating step, and can also prevent the thermally expanded base member 110 from pressing against the object to be magnetized 100. As a result, the method for manufacturing a permanent magnet according to this embodiment can prevent excessive thermal stress from being applied to the object to be magnetized 100 by the heated base member 110 or the positioning pin 7.

[0053] The permanent magnet (the object to be magnetized 100' after magnetization) according to this embodiment includes the following configuration. The upper end portion 110b1 of the base member 110 to which the object to be magnetized 100 is fixed is a flat surface that does not protrude in any direction in the vertical direction. Therefore, the permanent magnet according to this embodiment can prevent the thermally expanded base member 110 from pressing against the object to be magnetized 100 during the manufacturing process. As a result, the permanent magnet according to this embodiment can prevent excessive thermal stress from being applied to the object to be magnetized 100 by the base member 110.

[0054] The permanent magnet according to this embodiment (the object to be magnetized 100' after magnetization) includes the following configuration. The radial size of the through hole 100c is larger than the radial size of the positioning hole 110c. Therefore, in the manufacturing process, the permanent magnet according to this embodiment can prevent the positioning pin 7, which engages with the positioning hole 110c, from pressing against the object to be magnetized 100 due to thermal expansion. As a result, the permanent magnet according to this embodiment can prevent excessive thermal stress from being applied to the object to be magnetized 100 by the positioning pin 7.

[0055] In the method for manufacturing a permanent magnet described above, a mixture 101 is formed from magnetic powder and a thermosetting resin. However, the method for manufacturing a permanent magnet according to this embodiment is not limited to this. For example, the method for manufacturing a permanent magnet may involve forming a mixture 101 from magnetic powder, a thermosetting resin, and a lubricant. For example, calcium stearate can be used as the lubricant. The lubricant can be added to the magnetic powder at a concentration of 0.25 weight percent of the weight of the magnetic powder. When a lubricant is added to the mixture 101, it is possible to suppress the adhesion of the magnetized object 100 to the lower side surface 6a of the field section 6 after magnetization when the field section 6 is moved upward together with the heating section 4.

[0056] Furthermore, the method for manufacturing a permanent magnet described above uses Nd-Fe-B type magnet powder as the rare earth magnet powder. However, the method for manufacturing a permanent magnet according to this embodiment is not limited to that, and Sm-Fe-N type magnet powder or the like can be used as the rare earth magnet powder.

[0057] Furthermore, it is preferable that the magnetization device 1 is placed inside a chamber (not shown), and that the inside of the chamber be evacuated or filled with an inert gas.

[0058] Furthermore, when Nd-Fe-B type magnetic powder is used as the magnetic powder, it is preferable to apply a rust-preventive treatment to the magnetized object 100' after magnetization.

[0059] Furthermore, the present invention is not limited by the embodiments described above. Configurations that appropriately combine the above-described components are also included in the present invention. Moreover, further effects and modifications can be easily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the embodiments described above, and various modifications are possible. [Explanation of Symbols]

[0060] 6 Field section, 6a Downward side surface (contact surface), 63 Field section permanent magnet (permanent magnet), 7 Positioning pin, 100 Object to be magnetized, 100' Object to be magnetized after magnetization (permanent magnet), 100a Upward side surface (contact surface), 100c Through hole, 102 Magnetization area, 110 Base member, 110b1 Upper end, 110c Positioning hole, s1 Gap, T2 Vertical thickness of object to be magnetized

Claims

1. A process for forming a magnetized object by applying a predetermined pressure to magnetic powder and thermosetting resin, A heating step in which the permanent magnet of the field section is brought close to the object to be magnetized, which is placed on the base member, and the magnetized powder is heated to a temperature above the Curie point of the magnetized powder, thereby magnetizing the magnetized powder, and the thermosetting resin is melted and cured to fix the object to be magnetized to the base member, A method for manufacturing a permanent magnet, comprising at least [a specific element].

2. Prior to the heating step, the process includes a coating step of applying a release agent to at least one of the contact surfaces between the field element and the object to be magnetized. A method for manufacturing a permanent magnet according to claim 1.

3. The thickness of the magnetized object formed by the above-mentioned magnetized object forming process is 1 to 2 mm in the vertical direction. A method for manufacturing a permanent magnet according to claim 1 or 2.

4. The aforementioned field section has a positioning pin that protrudes downward, The base member has a positioning hole into which the positioning pin fits, and an upper end that does not protrude in either the vertical or vertical direction, and on which the object to be magnetized is placed. The object to be magnetized has a through hole through which the positioning pin can be inserted, In the heating step in which the positioning pin and the positioning hole are engaged, a gap is formed between the inner circumferential surface of the through hole and the outer circumferential surface of the positioning pin. A method for manufacturing a permanent magnet according to any one of claims 1 to 3.

5. A magnetized object formed in a ring shape and having a magnetized region and a non-magnetized region, The base member to which the object to be magnetized is fixed, Equipped with, The upper end of the base member to which the object to be magnetized is fixed is a flat surface that does not protrude in any direction in the vertical direction. Permanent magnet.

6. The base member has a positioning hole into which the positioning pin of the field section is fitted. The object to be magnetized has a through hole that penetrates the object in the vertical direction and through which the positioning pin can be inserted. The radial size of the through hole is larger than the radial size of the positioning hole. The permanent magnet according to claim 5.

7. The magnetic object to be attached is fixed to the base member solely by a hardened thermosetting resin. The permanent magnet according to claim 5 or 6.

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