Method for manufacturing a field element

Abstract

Provided is a manufacturing method of a magnetizing element capable of producing a bonded magnet in which a magnet is press-fitted into an outer shell with a low cost and with an inner peripheral surface of the magnet satisfying a desired accuracy. The present invention is a manufacturing method of a magnetizing element (F) in which a cylindrical bonded magnet (2) in which magnet particles are bonded using a thermosetting resin is fixed into a substantially bottomed cylindrical outer shell (1), and includes a softening step of reheating the bonded magnet after a thermosetting treatment to soften the bonded magnet, and a press-fitting step of press-fitting the bonded magnet after softening into the outer shell from an opening on one side of the outer shell. The outer shell has a cylindrical portion (11) in which at least a fixing portion (113) of the bonded magnet is made of a magnetic material, and a lid portion (12) coupled to the other side of the cylindrical portion. In the press-fitting step, the bonded magnet is relatively fed into the cylindrical portion while allowing a variation in the relative posture of the bonded magnet and the outer shell. Thus, the bonded magnet after softening can be stably fed into the outer shell, and the inner peripheral surface of the bonded magnet becomes the same degree of accuracy as the inner peripheral surface of the outer shell.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an excitation element having a bonded magnet serving as an excitation source fixed inside a housing. Background Technology

[0002] Excitation elements that use permanent magnets as excitation sources are manufactured, for example, by pressing a cylindrical bonded magnet (a permanent magnet for excitation) into a yoke or a housing that also serves as a yoke (appropriately referred to simply as a "yoke"). Descriptions relating to methods of manufacturing such excitation elements are found in the following patent documents.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-184642

[0006] Patent Document 2: WO2006 / 1304

[0007] Patent Document 3: WO2011 / 126026 Publication

[0008] Patent Document 4: Japanese Patent Application Publication No. 2005-33844

[0009] Patent Document 5: WO2006 / 059603

[0010] Patent Document 6: Japanese Patent Application Publication No. 2006-311661

[0011] Patent Document 7: Japanese Patent Application Publication No. 2007-28714

[0012] Patent Document 8: Japanese Patent Application Publication No. 2003-70194

[0013] Patent Document 9: Japanese Patent Application Publication No. 2000-37054

[0014] Patent Document 10: Japanese Utility Model Publication No. 55-178276 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] In Patent Documents 1-7, no adhesive is used; the bonded magnet is directly pressed into the yoke. Specifically, in Patent Document 1, the bonded magnet disposed within the yoke expands due to heating, thus pressing the two together. In Patent Document 2, a molded body (the bonded magnet before heat curing) is directly pressed into the yoke from the cavity, and the springback of the molded body is used to press the two together. In Patent Document 3, after the heated molded body (the bonded magnet before heat curing) is directly pressed into the yoke, the expansion of the molded body during the heat curing process (curing process) is used to press the two together. Patent Documents 1-3 are common in that they perform heat curing after the molded body is disposed or embedded into the yoke.

[0017] In patent documents 4-7, a bonded magnet (shaped body) that has undergone curing and reheating is pressed into a housing (yoke) to bond the two together. Although not detailed in these patent documents, this pressing is performed by considering that the bonded magnet softens due to reheating, and by binding the outer periphery of the housing to ensure the desired accuracy (coaxiality, roundness, cylindricality, etc.). It should be noted that the accuracy of the outer periphery of the housing has little impact on the performance of the motor, and is therefore only ensured for assembling the bonded magnet into the housing.

[0018] Incidentally, patent documents 8-10 also describe methods for mounting magnets to yokes. However, patent document 8 makes no mention of using thermosetting resin to bond magnets or the heating process during installation. Furthermore, patent documents 9 and 10 don't even describe the bonded magnets themselves.

[0019] The present invention was made in view of the following circumstances, and its object is to provide a new manufacturing method that can reduce the production cost of excitation elements using cylindrical bonded magnets.

[0020] Methods for solving problems

[0021] To solve this problem, the inventors conducted intensive research, resulting in the successful, low-cost production of excitation elements that meet desired specifications by pressing a softened cylindrical bonded magnet into a housing made of multiple components. This achievement led to the invention described below.

[0022] Manufacturing Method of Excitation Components

[0023] (1) The present invention is a method for manufacturing an excitation element, which is a method for manufacturing an excitation element by fixing a cylindrical bonded magnet, which is made of magnetic particles bonded by thermosetting resin, into a generally bottomed cylindrical shell. The method includes: a softening step, in which the thermosetting bonded magnet is reheated to soften the bonded magnet; and a pressing step, in which the softened bonded magnet is pressed into the shell from an opening on one side of the shell. The shell has at least a cylindrical part of the fixing part of the bonded magnet made of magnetic material and a cover part attached to the other side of the cylindrical part. In the pressing step, the bonded magnet is fed into the cylindrical part while allowing relative posture changes between the bonded magnet and the shell.

[0024] (2) According to the manufacturing method of the present invention, excitation elements that meet the required specifications can be produced at low cost. The reasons for this are as follows.

[0025] First, the shell formed by combining the cylindrical portion with the cover portion (appropriately referred to as a "combined shell") can be produced at a lower cost compared to a shell integrally formed through deep drawing or other methods (appropriately referred to as a "one-piece shell"). Specifically, by using a combined shell, for example, it is possible to improve material yield, reduce equipment (molds, etc.) costs, and reduce defect rates. In addition, it is basically sufficient for the shell (cylindrical portion) to ensure the accuracy (cylindricity, roundness, etc.) of the inner circumferential surface into which the bonded magnet is pressed, and its outer circumferential surface, ends, etc., do not necessarily need to be of high precision. These points also contribute to reducing the production cost of the combined shell.

[0026] Next, in this invention, when pressing the bonded magnet into such a bonding shell, the softened bonded magnet is fed into a cylindrical portion that allows for relative posture changes. As a result, the bonded magnet is stably pressed into the shell (cylindrical portion), and its inner circumferential surface can achieve the desired accuracy corresponding to the inner circumferential surface of the shell. Thus, an excitation element that meets the required specifications and achieves reduced production costs can be obtained.

[0027] Incidentally, the reasons for achieving both press-fit stabilization of the bonded magnet and ensuring the accuracy of its inner circumferential surface through the manufacturing method of the present invention are as follows.

[0028] Bonded magnets are formed by curing a mixture of magnet particles and a resin that has been heated, softened, or melted in a molding die cavity. The molded body is typically removed from the cavity before complete cooling and solidification. Such a molded body may not possess sufficient strength and rigidity, and therefore may experience slight deformation (strain) due to handling during removal from the cavity and subsequent transportation. This strain is not repaired during subsequent heat curing (curing treatment) and may be inherited by the bonded magnet. Heat-cured bonded magnets, due to their sufficient strength and rigidity, can be directly pressed into a shell. However, if bonded magnets with residual strain are directly pressed into a shell, the accuracy of the inner circumferential surface of the bonded magnet may not be guaranteed.

[0029] In contrast, the plasticity of the bonded magnet, softened by reheating after thermosetting, is restored, allowing the inner circumferential surface of the bonded magnet pressed into the cylindrical portion of the outer shell to take on a shape that follows the inner circumferential surface of the cylindrical portion. As a result, the inner circumferential surface of the bonded magnet can achieve a precision that corresponds to the precision of the inner circumferential surface of the cylindrical portion.

[0030] However, the softened bonded magnet has lower strength (bending strength, etc.) and rigidity compared to the cured bonded magnet. Therefore, if such a bonded magnet is forcibly pressed into the outer shell, it may deform due to excessive bending stress. Thus, in this invention, the bonded magnet is pressed in a state that allows for relative posture variation with respect to the outer shell. Through this relative posture variation, the outer shell and the bonded magnet are automatically aligned, suppressing excessive bending stress on the bonded magnet during pressing. In this way, even a softened bonded magnet can be stably pressed into the cylindrical portion without experiencing excessive stress concentration.

[0031] Thus, it can be considered that the manufacturing method according to the present invention can stably press the bonded magnet into the housing, and can also ensure the accuracy of the inner circumferential surface of the bonded magnet after pressing, thereby reducing the production cost of the excitation element.

[0032] "other"

[0033] (1) In this specification, for convenience, the side where the pressed-in body (bonding magnet) is located is referred to as one side, and the side where the pressed-in body (outer shell) is located is referred to as the other side. Regarding the outer shell, the side with the opening through which the bonding magnet is inserted is called one side, and the opposite side is called the other side. Regarding the bonding magnet, the front side (inner side) into which it is inserted (delivered) is called the other side, and the rear side (near the front side) is called one side. For example, if the outer shell is pressed in from above the bonding magnet, the bottom side is called one side, and the top side is called the other side.

[0034] (2) As used in this specification, “posture change” means that at least one of the housing and the bonded magnet moves (rotates, slides, etc.) as a whole while maintaining its own shape. In this respect, posture change is different from its own shape change or deformation (plastic deformation, elastic deformation) accompanied by local displacement.

[0035] (3) Unless otherwise specified, “x~y” in this specification includes the lower limit value x and the upper limit value y. It is possible to use any value contained in the various values ​​or ranges of values ​​recorded in this specification as new lower or upper limits to create a new range such as “a~b”. Attached Figure Description

[0036] Figure 1A This is a perspective view showing an excitation element (example).

[0037] Figure 1B This is a longitudinal sectional view (AA sectional view) of the excitation element.

[0038] Figure 2A This is a schematic cross-sectional view showing the initial stage (an example) of the toroidal magnet being pressed into the outer shell.

[0039] Figure 2B This is a schematic cross-sectional view showing the final stage (an example) of the toroidal magnet being pressed into the outer shell.

[0040] Figure 3A This is a schematic cross-sectional view showing an example of pressing a ring magnet into a housing that is offset from the central axis of the cylindrical part and the cover part.

[0041] Figure 3B This is a cross-sectional view schematically showing another example of pressing a ring magnet into a housing offset from the central axis of the cylindrical part and the cover part.

[0042] Figure 4 This is a cross-sectional view (BB section view) showing the inner surface side of the bearing fixture used in the press-in. Detailed Implementation

[0043] One or more structures, selected from those described in this specification, can be added to the structure of the present invention described above. Which embodiment is best varies depending on the object, required performance, etc. Structures related to the manufacturing method can become structures related to the object.

[0044] "shell"

[0045] The outer casing has at least a cylindrical portion and a cover portion located on its other side (especially the other end side). The cylindrical portion and the cover portion are not integrally formed, but are formed by joining separate components. The joining of the cylindrical portion and the cover portion is achieved, for example, by tightening, welding (including spot welding), etc. The cover portion may also be joined to a location other than the other end side of the cylindrical portion. The outer casing may also have other parts or components besides the cylindrical portion and the cover portion.

[0046] The cylindrical section can be constructed, for example, from a tube of a specified length, or by rounding a plate of a specified shape into a cylindrical shape. The rounded plate can be joined at both ends to form a cylindrical shape, or it can be held in a cylindrical shape by inserting an external ring. It should be noted that the inner circumferential surface of the cylindrical section can be formed, for example, by tightly fitting it against the outer circumferential surface of a cylindrical mandrel with ensured accuracy (cylindricity, etc.). This allows the inner circumferential surface of the cylindrical section to be given the desired accuracy. Furthermore, the outer circumferential surface of the cylindrical section can be either a cylindrical surface or a non-cylindrical surface. Incidentally, the portion of the cylindrical section for pressing and fixing the adhesive magnet (the fixing part) also serves as a magnetic yoke. Therefore, it is preferable that at least the fixing part is made of a magnetic material.

[0047] The cylindrical portion preferably has a tapered inlet (also called a "taper") with its inner circumferential surface expanding to one side on its opening side. This allows for smooth pressing of the bonded magnet into the housing. The angle of the tapered portion can be set, for example, to 5–12° relative to the central axis, and more preferably to 6–10°.

[0048] The cover can be, for example, a generally circular plate, a curved surface, or a flanged cylinder. Furthermore, the cover may only block the other end of the cylindrical portion, or it may constitute a bearing or bearing retainer for the armature housed within the excitation element. The cover and the cylindrical portion may be made of the same material or have different thicknesses.

[0049] Bonded Magnets

[0050] The bonded magnet is made by heat curing a cylindrical molded body composed of magnet particles and thermosetting resin.

[0051] (1) At least a portion of the magnetic particles is preferably rare-earth magnetic particles. This enables high performance and miniaturization of the bonded magnet (and consequently, the electric motor). The magnetic particles can be isotropic or anisotropic. The bonded magnet, which is at least composed of isotropic magnetic particles, is preferably magnetized after being pressed into the outer shell. The bonded magnet, which is composed of anisotropic magnetic particles, is preferably composed of a shaped body formed in a magnetic field orientation. In this case, it can also be further magnetized.

[0052] Rare earth magnetic particles include, for example, Nd-Fe-B based magnetic particles, Sm-Fe-N based magnetic particles, and Sm-Co based magnetic particles. Magnetic particles can also exist in a mixture of multiple types. These multiple types of magnetic particles can differ in composition, particle size distribution, or both.

[0053] (2) Thermosetting resins used as adhesive resins include, for example, epoxy resins, phenolic resins, unsaturated polyester resins, amino resins, polyamide resins, polyimide resins, polyamide-imide resins, urea resins, melamine resins, urea-formaldehyde resins, diallyl phthalate, polyurethane, etc. It should be noted that in this specification, when thermosetting requires curing agents and curing aids, this also includes those referred to as thermosetting resins in mainland China.

[0054] In bonded magnets, various additives may be appropriately included to improve the wettability and adhesion of the softened or melted thermosetting resin and magnet powder. Examples of such additives include alcohol-based lubricants, phthalate-based or silane-based coupling agents, etc.

[0055] (3) The conditions for thermosetting treatment should be adjusted appropriately according to the type of thermosetting resin and the size of the bonded magnet. If the thermosetting resin is epoxy resin, the conditions also depend on the type, but it is best to adjust them within the range of heating temperature: 80 to 200°C and heating time: 10 to 60 minutes. The heating atmosphere can also be atmospheric, but a non-oxidizing atmosphere (Ar, N2, vacuum, etc.) can suppress the deterioration of the bonded magnet (magnet particles) caused by oxidation.

[0056] Softening Process

[0057] The softening process involves reheating the thermosetting bonded magnet to soften it. Ideally, the softening should balance the plasticity of the bonded magnet into a cylindrical shape along the inner circumference of the shell with the mechanical properties (strength, rigidity, etc.) that allow the bonded magnet to be pressed into the shell.

[0058] The reheating temperature of the bonded magnet is adjusted appropriately according to the type of thermosetting resin, its mass ratio, and its heat history. Generally, the bonded magnet is preferably heated to a temperature lower than its thermosetting treatment temperature (T0) + 100 degrees Celsius. For example, this temperature is preferably below T0 + 70°C, below T0 + 40°C, below T0 + 10°C, below T0, or below T0 - 20°C. Furthermore, this temperature is preferably above 40°C, and more preferably above 50°C. As an example, if the thermosetting resin is a phenolic varnish-type epoxy resin, then this temperature is preferably set, for example, to 270–40°C, 240–40°C, 210–50°C, 180–60°C, 150–90°C, 140–100°C, and more preferably 130–110°C. In addition, as an example, if the thermosetting resin is a bisphenol A type epoxy resin, the temperature is preferably set to, for example, 150–40°C, 120–40°C, 90–40°C, 80–50°C, or further to 70–55°C.

[0059] If the reheating temperature is too high, the mechanical properties of the bonded magnet will decrease, making it difficult to press in. If the reheating temperature is too low, the plasticity of the bonded magnet will be insufficient, making it difficult to deform along the inner circumferential surface of the shell. It should be noted that the heating temperature of the bonded magnet mentioned in this specification refers to the atmosphere temperature of the heating furnace, etc. When the thermosetting temperature changes or when the thermosetting process is carried out in multiple stages, it is best to use the highest temperature in the thermosetting process as the reference for the reheating temperature (T0).

[0060] The heating time for bonding magnets can be adjusted appropriately according to their size (wall thickness), the type of thermosetting resin, and the mass ratio. For example, reheating is best performed for 10 seconds to 1 hour, or even more preferably for about 20 seconds to 30 minutes.

[0061] Pressing Process

[0062] During the pressing process, the bonding magnet is fed into the housing while allowing relative positional changes between the bonding magnet and the housing.

[0063] (1) Regarding the posture change, provided that the bonding magnet is gradually fed into the outer shell, at least one of the bonding magnet and the outer shell can be movable in the direction of feeding. If such posture change can be performed, the bonding magnet or the outer shell can be in a completely unrestrained state (free state) or in a state partially supported by a guide or the like.

[0064] Postural changes can be, for example, tilting (rotational motion) or lateral movement (translational motion), or a combination of both. It should be noted that lateral movement (sliding) is movement in a direction intersecting the feeding direction (e.g., approximately orthogonal). For convenience, movement in the approximate feeding direction is also referred to as longitudinal movement.

[0065] Incidentally, tilting can be a rotation centered on a specific point (e.g., the contact point between the housing and the clamp) or a rotation about a changing instantaneous center. Tilting can be an oscillation (wobbling) relative to the feeding direction (an axis related to the inner circumferential surface of the cylindrical part or the inner circumferential surface of the bonded magnet) or a rotation (rotation / tilting) about that feeding direction. It should be noted that the change in posture can be achieved by the movement of either the housing or the bonded magnet, or by the movement of both (linkage).

[0066] (2) Insertion can be performed by moving one of the housing and the bonded magnet, or by moving both of them. Typically, insertion is performed while restricting the movement of one of the housing and the bonded magnet, and simultaneously moving the other. For example, the bonded magnet is inserted into the housing while supporting it and restricting its movement to the other side. In this case, the support of the housing can be point-like, line-like, surface-like, or a combination of two or more of these. As long as relative posture changes are possible, the support (movement restriction) of the housing can be performed at the other end or at a location other than that (e.g., the middle section). The other end of the supported housing can be the other end of the cylindrical section or the other end of the cover section. The other end of the supported cover section can be the outer edge or the central section.

[0067] The interference fit (press-in allowance) should be adjusted appropriately based on the thickness of the bonded magnet, the housing wall, the rigidity of the bonded magnet, and the application of the motor. Ideally, the interference fit should be at least sufficient to prevent the bonded magnet from detaching from the housing after the pressing-in process.

[0068] Excitation Components

[0069] The excitation element obtained by the manufacturing method of the present invention is used, for example, in electric motors (including generators) such as DC motors and AC motors. Such excitation elements typically constitute a stator.

[0070] Example

[0071] The present invention will be described more specifically using the example of manufacturing an excitation element for an electric motor by pressing a ring magnet (bonded magnet) into a housing.

[0072] Excitation Components

[0073] exist Figure 1A The image shows an example of an excitation element F for a motor (referred to as "excitation element F"). Additionally, in... Figure 1B It shows Figure 1AThe cross-section AA is shown. The excitation element F consists of a housing 1 and an annular magnet 2 fixed inside the housing 1 without adhesive. Details of these components are as follows. It should be noted that, for ease of explanation in this embodiment, the vertical direction, horizontal direction, feeding direction, or lateral direction are defined as shown in the figures. The lower (side) and upper (side) shown in each figure correspond to one side and the other side as described in this specification, respectively, and the vertical direction from lower to upper is the feeding direction. Furthermore, the same reference numerals are used for components already described, and their descriptions are appropriately omitted.

[0074] (1) The outer casing 1 is composed of a cylindrical portion 11 and a cover portion 12 fixed to the other side thereof. The cylindrical portion 11 further comprises, from one side, an opening portion 111, a tapered portion 112 (inlet portion), a fixing portion 113, and a claw portion 114 in sequence. The opening portion 111 is larger in diameter than the fixing portion 113. The tapered portion 112 (inlet portion) located in the middle of the two smoothly connects the inner and outer peripheral surfaces of the two. It should be noted that, for the convenience of explanation, the diameter difference between the opening portion 111 and the fixing portion 113 is exaggerated in the illustration, but in reality it is very small (for example, the diameter difference is less than 1 mm).

[0075] The claw portion 114 is three protrusions extending from the other end of the fixing portion 113. The claw portion 114 is formed corresponding to the cut portion 124 of the cover portion 12, which will be described later.

[0076] The cover 12 has a flange 121 and a cylindrical retaining portion 122 protruding from near the center of the flange 121 to the other side. Three slits 124 are formed at approximately 120° intervals on the outer periphery of the flange 121. A bearing supporting the rotating shaft of the motor is inserted into the inner cylindrical portion 123 of the retaining portion 122. It should be noted that the cover 12 blocks the other side of the cylindrical portion 11. That is, through the cylindrical portion 11 and the cover 12, the outer casing 1 becomes a generally bottomed cylindrical shape.

[0077] Both the cylindrical portion 11 and the cover portion 12 are made of plates obtained by cutting or punching soft iron steel plates (magnetic materials) into desired shapes. The cylindrical portion 11 is made of a joined cylindrical body formed by winding the plate into a cylindrical shape and joining its ends by welding or tightening. If the cut portion 124 of the cover portion 12 is fitted into the protrusion (the precursor of the claw portion 114) formed on the upper end side of the joined cylindrical body and the protrusion is bent inward, the other side of the cylindrical portion 11 becomes the state after the cover portion 12 is tightened and fixed by the claw portion 114. After the cover portion 12 is fixed or at the same time as the cover portion 12 is fixed, the opening portion 111, the conical portion 112, the fixing portion 113, and the retaining portion 122 of the cylindrical portion 11 are formed by a mandrel (punch). As a result, the inner circumferential surface of each part achieves the desired accuracy. Incidentally, the accuracy of the outer circumferential surface of the cylindrical part 11 and the upper surface (other end) of the cover part 12 has a much smaller impact on the performance of the excitation element F compared to the accuracy of the inner circumferential surface. Therefore, strict dimensional tolerances and geometric tolerances as those for the inner circumferential surfaces are not set for them.

[0078] (2) The ring magnet 2 is made of a bonded magnet after the composite material made of rare earth magnetic particles and thermosetting resin is compressed and molded into a cylindrical shape and then thermosetting is subjected to heat curing treatment. The ring magnet 2 has a cylindrical part 22, an annular end face 21 on one side thereon and an annular end face 23 on the other side thereon.

[0079] During the post-thermosetting stage, no strict dimensional or geometric tolerances are set for the inner circumferential surface 22a and the outer circumferential surface 22b of the cylindrical portion 22. However, the inner circumference or wall thickness (lateral / radial) of the cylindrical portion 22 is within a specified range.

[0080] Fixtures

[0081] exist Figure 2A and Figure 2B (Hereinafter referred to as "Figure 2") shows the supporting clamp 3 and the conveying clamp 4 used when pressing the toroidal magnet 2 into the housing 1. Their details are as follows.

[0082] (1) The bearing fixture 3 is a generally bottomed cylindrical body made of tool steel. The bearing fixture 3 has an opening 31, a cylindrical part 32 and a bottom 33 on one side. The inner diameter of the cylindrical part 32 is larger than the outer diameter of the cylindrical part 11 (opening 111) of the outer shell 1. Therefore, there is a gap between the inner peripheral surface 32a of the bearing fixture 3 and the outer peripheral surface 11b of the outer shell 1, and the outer shell 1 can tilt, move laterally and perform other posture changes within the range of this gap.

[0083] A cylindrical guide pin 34 protruding downwards from the center (one side) and three protrusions 35 (protrusions) formed by curved surfaces are formed on the inner surface side of the bottom 33. Each protrusion 35 is evenly arranged on the lower outer periphery of the guide pin 34. It should be noted that the clamping device 3 is configured (fixed) so that the guide pin 34 is in the vertical direction (feeding direction).

[0084] (2) The conveying clamp 4 is a stepped cylinder made of tool steel. The conveying clamp 4 has a cylindrical base 41 and a cylindrical insert 42 extending upward (to the other side) from the base 41. The outer diameter of the base 41 is slightly smaller than the outer diameter of the annular magnet 2 (outer peripheral surface 22b). The outer diameter of the insert 42 is smaller than the outer diameter of the base 41 and smaller than the inner diameter of the annular magnet 2 (inner peripheral surface 22a). The annular magnet 2 is mounted on an annular lower surface 411 formed between the base 41 and the insert 42 in such a way that the end faces 21 are in contact. There is also a gap between the outer peripheral surface 42b of the insert 42 and the inner peripheral surface 22a of the annular magnet 2, within which the annular magnet 2 can make slight posture changes (tilting or lateral movement, etc.).

[0085] It should be noted that the length of the inner insertion part 42 in the vertical direction is shorter than that of the annular magnet 2, and the upper surface 421 of the inner insertion part 42 does not protrude from the end face 23 of the annular magnet 2 placed on the transport jig 4. Therefore, the transport jig 4 can also feed the annular magnet 2 to the position where the end face 23 of the annular magnet 2 abuts against the lower surface 12a (inner bottom surface of the outer casing 1) of the cover part 12 or near it.

[0086] A hydraulic cylinder (not shown) is provided on one side of the conveying clamp 4. By controlling the supply of hydraulic pressure to the hydraulic cylinder, the conveying clamp 4 can move to the specified position at the desired speed.

[0087] Incidentally, as shown in Figure 2, in this embodiment, the bearing clamp 3 and the conveying clamp 4 are moved relative to each other in a straight line with their central axes approximately aligned. The bearing clamp 3 and the conveying clamp 4 can also move relative to each other while tilting, swaying, or otherwise altering the central axis of at least one of them. That is, at least one of the bearing clamp 3 and the conveying clamp 4 can also undergo posture changes with respect to the pressing direction. For example, at least one clamp can be swayed via a universal joint extending in the pressing direction. Thus, the posture change of at least one of the bearing clamp 3 and the conveying clamp 4 can be performed together with or instead of the posture change between the housing 1 and the annular magnet 2.

[0088] Assembly

[0089] (1) Softening process

[0090] The ring magnet 2 is preheated in a heating furnace (atmospheric atmosphere) at a temperature lower than the heat curing temperature. As a result, the ring magnet 2 softens and becomes malleable while maintaining the strength and rigidity required for pressing.

[0091] (2) Installation procedure

[0092] The softened ring magnet 2 is inserted from the top into the inner insertion part 42 and placed into the conveying clamp 4 (see reference). Figure 2A As described above, since there is a gap between the inner circumferential surface 22a of the annular magnet 2 and the inner insertion portion 42 of the conveying clamp 4, the annular magnet 2 can move laterally within the range of this gap.

[0093] The opening 111 of the outer casing 1 is inserted into the annular magnet 2 from above. At this time, the outer casing 1 is held in a slightly inclined state from the vertical direction, for example, with the inner peripheral surface of the cone 112 abutting against the outer peripheral edge of the end face 23 of the annular magnet 2 (see reference). Figure 2A ).

[0094] (3) Pressing process

[0095] With the outer casing 1 covering the annular magnet 2, the hydraulic cylinder is operated to move the conveying clamp 4 upward. Thus, the outer casing 1 first enters the receiving clamp 3. Because there is a gap between the outer peripheral surface 11b of the outer casing 1 and the inner peripheral surface 32a of the receiving clamp 3, the outer casing 1 can perform kinetic changes (lateral movement, tilting, etc.) within the range of this gap.

[0096] As the conveyor clamp 4 rises, as Figure 2A As shown, the guide pin 34 of the bearing clamp 3 is inserted into the retaining portion 122 of the housing 1, and any protrusion 35 of the bearing clamp 3 begins to make point contact with the upper surface of the flange portion 121 of the housing 1 (the other end of the cover portion).

[0097] Within the gap formed between the guide pin 34 and the retaining part 122, the outer casing 1 tilts or moves laterally (slides / glides) about the contact point between the upper surface of the flange part 121 and the protrusion 35. In this way, the outer casing 1 and the annular magnet 2 are automatically aligned (the central axes of the fixing part 113 and the annular magnet 2 are approximately aligned). Then, the upper surface of the cover part 12 also abuts against the other protrusions 35, and the upward (other) movement of the outer casing 1 is restricted.

[0098] If the conveyor clamp 4 rises further, then as Figure 2BAs shown, the ring magnet 2 is inserted into the fixing part 113 while it is aligned by the outer shell 1. At this time, since the ring magnet 2 is in a softened state, its inner circumferential surface 22a is reshaped along the inner circumferential surface 113a of the fixing part 113. In this way, the inner circumferential surface 22a of the ring magnet 2 becomes approximately the same precision (roundness, etc.) as the inner circumferential surface 113a of the fixing part 113. It should be noted that the ring magnet 2 can be inserted until its end face 23 abuts against the lower surface 12a of the cover part 12, or it can be left in the middle position before abutting.

[0099] In this way, an excitation element F can be obtained in which the inner circumferential surface 22a of the annular magnet 2, after being pressed into the outer shell 1, meets the desired accuracy (roundness, etc.). As can be clearly seen from the above process, the accuracy of the inner circumferential surface 22a does not depend on the accuracy of the outer circumferential surface 11b of the outer shell 1 or the cover 12.

[0100] Variations

[0101] (1) The protrusion 35 of the bearing clamp 3 can also contact the claw 114. In addition to point contact, the inner bottom surface of the bearing clamp 3 and the upper end surface of the outer shell 1 can also be in line contact or surface contact. It should be noted that even without the guide pin 34 and the protrusion 35 of the bearing clamp 3, the pressing as described above can still be performed.

[0102] Furthermore, the protrusion 35 of the clamping fixture 3 can also contact the retaining portion 122 of the cover portion 12. That is, even the retaining portion 122, as long as it is located on the other side of the cover portion 12, can become the other end of the cover portion 12. Moreover, the support (movement restriction) of the outer casing 1 can be provided, for example, by the middle portion of the cylindrical portion 11 (the outer peripheral surface side of the conical portion 112, etc.). It should be noted that when the outer peripheral surface of the conical portion 112 is used to support the outer casing 1, the diameter difference between the opening portion 111 and the fixing portion 113 can be made larger than the size example described in the embodiment.

[0103] One axial end of the ring magnet 2 may protrude near the tapered portion 112 or from the fixing portion 113. Even in this case, the accuracy (roundness, etc.) of the inner circumferential surface of the ring magnet 2 pressed into the fixing portion 113 can be ensured.

[0104] Alternatively, a third clamp with a cone portion 112 can be provided independently of the bearing clamp 3 and the conveying clamp 4. The third clamp is located on the opening side of the housing 1, is integral with the housing 1, and can be oriented relative to the bearing clamp 3.

[0105] (2) Figure 3A and Figure 3B(Referring to both together as "Figure 3"), as shown, there is a situation where the central axis L1 of the cylindrical portion 11 constituting the outer shell 1 intersects with the central axis L2 of the cover portion 12 (inner cylinder portion 123). Even in this case, according to the manufacturing method of the present invention, the annular magnet 2 can be properly pressed into the cylindrical portion 11 of the outer shell 1. This will be explained below. It should be noted that the intersection of the central axis L1 of the cylindrical portion 11 and the central axis L2 of the cover portion 12 (inner cylinder portion 123) may occur, for example, when the two are tightened together for assembly.

[0106] It should be noted that the fixed state of the cylindrical portion 11 and the cover portion 12 shown in Figure 3 (the intersection of the central axis L1 and the central axis L2) is exaggerated for ease of explanation. Furthermore, the central axis L0 shown in Figure 3 represents the central axis of the support clamp 3 (guide pin 34), the transport clamp 4 (insertion portion 42), or the annular magnet 2. In Figure 3, for ease of explanation, a state where these central axes are aligned is shown, but each central axis may deviate in the left-right direction. Incidentally, the central axis L2 of the cover portion 12 is generally approximately orthogonal to the end face of the flange portion 121.

[0107] If the conveying clamp 4 is moved toward the receiving clamp 3 in order to press the annular magnet 2 into the outer casing 1, the other end face of the cover 12 can contact the protrusion 35 of the receiving clamp 3. At this time, the annular magnet 2 partially abuts against the cylindrical portion 11, so the outer casing 1 can receive a force in the direction of rotation and laterally.

[0108] Thus, for example, the central axis L1 of the cylindrical portion 11 is not approximately aligned with the central axis L0 of the conveying clamp 4 (or the annular magnet 2). Figure 3A ) becomes a state where these central axes L1 and L0 are approximately aligned. Figure 3B At this time, the other side of the flange portion 121 of the cover portion 12 is in contact with only one or two of the protrusions 35 of the bearing clamp 3. In other words, even when there are more than three protrusions 35, the other side of the flange portion 121 is not in contact with more than three of these protrusions 35. At this time, the outer casing 1 is in a state where upward movement is restricted by one or two protrusions 35 that are in contact with the flange portion 121. In addition, the central axis L1 of the cylindrical portion 11 is in a state that is approximately constant or approximately parallel to the central axis L0 of the conveying clamp 4 or the annular magnet 2. If from this state ( Figure 3B The conveying clamp 4 moves further upward, and the annular magnet 2 is then properly pressed into the cylindrical part 11.

[0109] It should be noted that, comparing the case where the bearing fixture 3 has the protrusion 35 and the case where the protrusion 35 is not present, the presence of the protrusion 35 allows for a smaller change in the posture of the outer casing 1 under a smaller load. This is considered as follows: First, regarding rotation, when the bearing fixture 3 does not have the protrusion 35, the center of rotation of the outer casing 1 becomes the outer edge of the flange portion 121 in the cover portion 12. On the other hand, when the protrusion 35 is present, the center of rotation of the outer casing 1 becomes the contact portion between the protrusion 35 and the cover portion 12. Therefore, when the protrusion 35 is present, the center of rotation of the outer casing 1 is closer to the radially inward side, that is, the central axis L0.

[0110] Comparing the two, the angles of the rotation center (outer edge, protrusion 35) and the load-bearing position (contact between the cone 112 of the outer shell 1 and the ring magnet 2) are different. In other words, with the protrusion 35 present, a larger rotational torque is obtained under a smaller load. Therefore, it is possible to press the ring magnet 2 into the outer shell 1 while reducing the load acting on it, and deformation of the ring magnet 2 during pressing is suppressed.

[0111] Furthermore, considering lateral movement, with the protrusion 35 present, the protrusion 35 and the cover 12 are in near-point contact. On the other hand, without the protrusion 35, the bearing clamp 3 and the cover 12 are in near-surface contact. Therefore, comparing the two, with the protrusion 35 present, the frictional resistance applied to the cover 12 is sufficiently small. In other words, the load applied to the annular magnet 2 as a reaction force to the load applied to the outer shell 1 is also smaller, and at this point, deformation of the annular magnet 2 is also suppressed.

[0112] Thus, according to this embodiment (including variations), deformation of the annular magnet 2 accompanying the insertion can be avoided. In other words, by properly pressing the annular magnet 2 into the cylindrical portion 11, an excitation element F that meets the desired specifications can be obtained. It should be noted that the axial offset generated between the cover portion 12 and the cylindrical portion 11 can vary, so it is preferable to provide protrusions 35 at at least two locations across the central axis L2 of the cover portion 12. Of course, it is more preferable if there are three or more protrusions 35, and it is even more preferable if they are arranged at equal angular intervals. It should be noted that in this embodiment, the protrusions 35 and the cover portion 12 are in a state of near point contact, but the shape of the tip of the protrusion 35 is the same regardless of whether it is point-shaped, line-shaped, or surface-shaped.

[0113] According to the manufacturing method of the present invention, even if there are manufacturing errors (assembly errors, etc.) between the cylindrical portion 11 and the cover portion 12 constituting the housing 1, the desired excitation element F can be obtained. It should be noted that the errors generated during the manufacturing of the housing 1 are, of course, within the permissible range that meet the required specifications for the excitation element F. Within this range, the housing 1 is not limited to being composed of multiple components; it can also be a housing 1 integrally formed by deep drawing or the like. Even with integrally formed products, manufacturing errors (e.g., axial misalignment between the cylindrical portion 11 and the cover portion 12, etc.) may occur.

[0114] (3) Figure 4 ( Figure 3A As shown in section BB, three protrusions 35 are arranged approximately evenly (at equal angular intervals) on the inner surface of the receiving clamp 3. The central axis L0 of the conveying clamp 4 or the annular magnet 2 is preferably located within the area formed by connecting adjacent protrusions 35 with straight lines. Thus, regardless of the assembly state of the cylindrical portion 11 and the cover portion 12, a significant tilting of the inner and outer shell 1 of the receiving clamp 3 relative to the central axis L0 can be suppressed. Furthermore, when the conveying clamp 4 is inserted into the receiving clamp 3, the annular magnet 2 is properly pressed into the outer shell 1 regardless of the assembly state of the cylindrical portion 11 and the cover portion 12.

[0115] It should be noted that the number and size of the protrusions 35 can be adjusted appropriately. For example, if there are more than three protrusions 35 of approximately the same size, the cover 12 can stably contact any of the protrusions 35. However, if there are more protrusions 35, the range of motion of the outer shell 1 may become smaller.

[0116] Evaluation Example

[0117] (1) Outer shell and ring magnet

[0118] The effects of the softening and pressing processes described above were confirmed using the actual manufactured shell 1 and ring magnet 2.

[0119] The outer casing 1 is made of cold-rolled steel sheet, and its fixing part 113 is defined by the outer diameter: Inner diameter: Length: 70.0 mm. The inclination angle of the inner circumferential surface of the cone 112 relative to the central axis is set to 8°. The roundness of the inner circumferential surface 113a of the fixing part 113 is set to 0.10 mm. It should be noted that the roundness is measured in accordance with JIS B0021 (the same applies below).

[0120] The toroidal magnet 2 is manufactured as follows. The raw materials used are a composite material consisting of NdFeB-based rare-earth anisotropic magnet particles (MAGFINE magnet powder MF15P from Aichi Steel Corporation) and epoxy resin. It should be noted that the epoxy resin content relative to the total composite is 3% by mass. Furthermore, the epoxy resin is a phenolic varnish type, and its thermosetting temperature is 150°C.

[0121] The composite was heated and compressed simultaneously (150℃ × 130 MPa × 6 seconds) within the cavity of a mold to obtain a cylindrical molded body (outer diameter: (30mm). The molded body was heated in an atmospheric furnace and subjected to thermosetting treatment (150℃ × 40 minutes). In this way, a ring magnet 2 composed of bonded magnets was prepared.

[0122] (2) Assembly

[0123] First, use Figure 2A The ring magnet 2, after the softening process, is loaded into the housing 1 by the bearing fixture 3 and the conveying fixture 4 (pressing process). The softening process involves heating the ring magnet 2 in an atmospheric furnace (150°C × 30 seconds). The pressing process is performed with a load of 985 N and a moving speed of 30 mm / sec.

[0124] The roundness of the inner circumferential surface 22a of the annular magnet 2, which is thus installed into the outer casing 1, is 0.12 mm.

[0125] (3) Comparative Examples

[0126] When the aforementioned pressing process is performed on the annular magnet 2 without a softening process, cracks sometimes occur on the inner circumferential surface 22a of the annular magnet 2. In addition, if the annular magnet 2 after the aforementioned softening process is fed into the outer casing 1 without allowing changes in the posture of the outer casing 1 and the annular magnet 2, an abnormal load occurs, and it fails to be pressed in.

[0127] (4) Evaluation

[0128] Based on the various measurement results (roundness), it was confirmed that by pressing the softened toroidal magnet 2 into the outer shell 1 in a state that allows for ergonomic variation, the inner circumferential surface 22a of the toroidal magnet 2 can achieve the desired accuracy. Conversely, it was also known that if the softening process is omitted or the pressing process is performed without allowing for ergonomic variation, it is difficult to press the toroidal magnet 2 into the outer shell 1 stably.

[0129] Furthermore, the same evaluation was also conducted on the housing 1 assembled with the cover portion 12 and the cylindrical portion 11 axially offset. As a result, it was confirmed that by pressing it in a state with permissible posture variation as described above, the inner circumferential surface 22a of the toroidal magnet 2 can also achieve the desired accuracy.

[0130] Explanation of reference numerals in the attached figures

[0131] 1. Outer shell

[0132] 11 Cylindrical section

[0133] 12 covers

[0134] 2. Ring magnet (bonded magnet)

[0135] 3 bearing fixture

[0136] 4. Conveying clamps.

Claims

1. A method for manufacturing an excitation element, comprising fixing a cylindrical bonded magnet, formed by bonding magnetic particles with thermosetting resin, into a generally bottomed cylindrical shell to form the excitation element, wherein... include: The softening process involves reheating the heat-cured bonded magnet to soften it. and In the pressing process, the softened bonded magnet is pressed into the housing through an opening on one side of the housing. The housing has a cylindrical portion and a cover portion attached to the other side of the cylindrical portion, wherein at least the fixing portion of the bonded magnet in the cylindrical portion is made of magnetic material. In this pressing process, the adhesive magnet is fed into the cylindrical portion while allowing relative positional changes between the adhesive magnet and the outer casing. The pressing process is performed by moving the adhesive magnet to the other side while allowing the outer casing to tilt or move laterally.

2. The method for manufacturing the excitation element according to claim 1, The pressing process is performed by supporting the other end of the housing to restrict its movement to the other side.

3. The method for manufacturing the excitation element according to claim 2, The other end of the outer shell is the other end of the cover.

4. The method for manufacturing the excitation element according to any one of claims 1 to 3, The cover is joined to the other end of the cylindrical portion by tightening or welding.

5. The method for manufacturing the excitation element according to any one of claims 1 to 3, The cylindrical portion has a tapered inlet portion with its inner circumferential surface expanding to one side, located on a side closer to the fixed portion.

6. The method for manufacturing the excitation element according to any one of claims 1 to 3, The softening process is performed by heating the bonded magnet at a temperature lower than (T0+100°C) that is 100°C higher than the thermosetting temperature (T0).

7. The method for manufacturing the excitation element according to any one of claims 1 to 3, The outer casing is for use with an electric motor.

8. The method for manufacturing the excitation element according to any one of claims 1 to 3, The pressing process is performed using a bearing fixture that restricts the movement of the housing to the other side and a conveying fixture that feeds the bonding magnet into the housing. The bearing clamp has at least one protrusion that engages with the other end of the housing.

9. The method for manufacturing the excitation element according to claim 8, The conveying clamp feeds the adhesive magnet into the housing while the other end of the housing is in contact with the protrusion.

10. The method for manufacturing the excitation element according to claim 8, The protrusion is composed of three or more protrusions that are separated from each other.

11. The method for manufacturing the excitation element according to claim 10, The conveying clamp feeds the bonded magnet in such a manner that the central axis of the bonded magnet intersects with the area formed by connecting adjacent protrusions in a straight line.

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