Connecting body, compacted powder body, and method for manufacturing a compacted powder body.

Abstract

The present invention provides a connected body in which the first and second members are stably connected, even if at least one of the first and second members connected by screws is a compacted powder molded body. [Solution] The connecting body comprises a first member, a second member positioned in contact with the first member, and a screw that penetrates the first member and reaches the second member, connecting the first member and the second member, wherein at least one of the first member and the second member is a compacted body. The compacted body comprises a first surface facing the head of the first member or the screw that is in contact with the compacted body, a recess formed on the first surface, and a first hole extending from the recess in which the shaft of the screw is positioned. The opening area of ​​the recess is larger than the opening area of ​​the first hole, and the inner circumferential surface of the recess does not have cutting marks.

Description

Technical Field

[0001] The present disclosure relates to a connected body, a compacted powder molded body, and a method for manufacturing a compacted powder molded body.

Background Art

[0002] In recent years, attempts have been made to connect a compacted powder molded body manufactured by pressure-molding powder to another member using a tapping screw. As such a technique, Patent Document 1 discloses a connected body in which a first member and a second member independent of each other are connected by a tapping screw. At least one of the first member and the second member in this connected body is a compacted powder molded body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a tapping screw is screwed into a pilot hole formed in a compacted powder molded body, screw grooves are formed on the inner peripheral surface of the pilot hole by the tapping screw. When the tapping screw processes the pilot hole, burrs are generated. The burrs protrude from the opening of the pilot hole. Here, when the compacted powder molded body and another member are overlapped and the tapping screw is screwed from the other member toward the compacted powder molded body, the burrs are sandwiched between the compacted powder molded body and the other member, and a gap is likely to form between the compacted powder molded body and the other member. Also, when the compacted powder molded body and another member are overlapped and the tapping screw is screwed from the compacted powder molded body toward the other member, the burrs are sandwiched between the head of the tapping screw and the compacted powder molded body, and a gap is likely to form between the head and the compacted powder molded body. In any case, there is a risk that the connection between the compacted powder molded body and the other member becomes unstable due to the burrs.

[0005] One of the objectives of this disclosure is to provide a connected body in which the first member and the second member are stably connected, even if at least one of the first and second members connected by screws is a compacted powder molded body. [Means for solving the problem]

[0006] The connecting body of the present disclosure comprises a first member, a second member disposed in contact with the first member, and a screw that penetrates the first member and reaches the second member, connecting the first member and the second member, wherein at least one of the first member and the second member is a powder compact. The powder compact has a first surface facing the head of the first member or the screw that is in contact with the powder compact, a recess formed on the first surface, and a first hole extending from the recess in which the shaft of the screw is disposed. The opening area of ​​the recess is larger than the opening area of ​​the first hole, and the inner circumferential surface of the recess does not have cutting marks. [Effects of the Invention]

[0007] The connected body of this disclosure is a connected body in which the first member and the second member are stably connected, even if at least one of the first member and the second member is a compacted powder molded body. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of the connecting body according to Embodiment 1. [Figure 2] Figure 2 is a magnified view of a portion of Figure 1. [Figure 3] Figure 3 is an explanatory diagram illustrating the procedure for manufacturing a compacted powder molded body provided in the connecting body according to Embodiment 1. [Figure 4] Figure 4 is a partially enlarged cross-sectional view of a powder compact manufactured by the mold shown in Figure 3. [Figure 5] Figure 5 is a schematic diagram of the connecting body according to Embodiment 2. [Figure 6] Figure 6 is a schematic diagram of the connecting body according to Embodiment 3. [Figure 7] Figure 7 is a schematic diagram of the connecting body according to Embodiment 4. [Figure 8] Figure 8 is a schematic diagram of the connecting body according to Embodiment 5. [Figure 9] Figure 9 is a schematic diagram of the rotating electric machine according to Embodiment 6. [Figure 10] Figure 10 is a schematic diagram showing a part of the rotating electric machine according to Embodiment 7. [Figure 11] Figure 11 is a schematic diagram showing a part of the rotating electric machine according to Embodiment 8. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] In the process of investigating the above problems, the inventors conceived of forming a recess in the opening of the pilot hole where a tapping screw is placed in a powder compact. In this case, even if a burr protrudes from the opening of the pilot hole when the tapping screw is screwed in, the burr is contained within the recess. However, because powder compacts are brittle, if a recess is formed by machining or other processes, the edges of the recess opening are prone to chipping. Furthermore, the effort required to perform machining reduces the productivity of the powder compact. Based on these findings, the inventors have completed the configuration of the present disclosure. Embodiments of the present disclosure will be described below.

[0010] <1> The connecting body of the present disclosure comprises a first member, a second member disposed in contact with the first member, and a screw that penetrates the first member and reaches the second member, connecting the first member and the second member, wherein at least one of the first member and the second member is a powder compact. The powder compact has a first surface facing the head of the first member or the screw that is in contact with the powder compact, a recess formed on the first surface, and a first hole extending from the recess in which the shaft of the screw is disposed. The opening area of ​​the recess is larger than the opening area of ​​the first hole, and the inner circumferential surface of the recess does not have cutting marks.

[0011] The first hole formed in the compacted molded body of the connecting body is a screw hole into which a screw is screw-connected, or a through-hole through which a screw passes. In this specification, a hole formed in the compacted molded body before being incorporated into the connecting body, in which the shaft portion of a screw is placed during the manufacturing of the connecting body, is called a base hole. The inner circumferential surface of this base hole does not have a female thread portion formed for screw connection. When a tapping screw is screwed into the base hole during the manufacturing of the connecting body, that is, when the base hole functions as a pilot hole, the inner circumferential surface of the base hole is threaded by the tapping screw, and a female thread portion is formed on the inner circumferential surface of the base hole. In this case, the base hole with the female thread portion formed during the manufacturing of the connecting body becomes the first hole in the connecting body. Here, as shown in Embodiment 4 with reference to Figure 7, there may be cases where the screw connecting the first member and the second member is not a tapping screw. In this case, the inner diameter of the base hole is made larger than the outer diameter of the screw. During the manufacturing of the connecting body, the base hole is not threaded, and the shaft portion of the screw is simply inserted into the base hole, so the base hole of the compacted molded body becomes the first hole of the connecting body as is. The following explanation will primarily describe the connection between the first and second components using self-tapping screws.

[0012] the above <1> In this connecting structure, screws are attached from the first member toward the second member. If the first member is a compacted powder molded body, the recess in the first member faces the screw head. If the screws connecting the first and second members are self-tapping screws, the burrs generated when the base hole is threaded are contained within the space enclosed by the recess in the first member and the screw head. This prevents burrs from getting caught between the first member and the screw head, ensuring a secure connection between the first and second members.

[0013] If the second component is a compacted powder molded body, the recess of the second component faces the first component. If the screw connecting the first and second components is a self-tapping screw, the burr generated when the base hole is threaded is contained within the space enclosed by the recess of the second component and the first component. This prevents the burr from being caught between the first and second components, ensuring a secure connection between them.

[0014] The inner peripheral surface of the recess in the above-mentioned connecting body has no cutting marks. Cutting marks, also called tool marks, have a characteristic appearance and can be discriminated visually. Therefore, the absence of cutting marks on the inner peripheral surface of the recess can be confirmed by visually inspecting the inner peripheral surface of the recess. The fact that the inner peripheral surface of the recess has no cutting marks indicates that the recess was not formed by cutting, but was formed during the pressure molding of the compact. That is, by visually inspecting the inner peripheral surface of the recess, it can be seen that the inner peripheral surface of the recess is not a cutting surface formed by cutting, but a compression molding surface on which the shape of the mold is transferred. When the recess is formed by pressure molding, chipping and the like are less likely to occur in the recess. If there is no chipping in the recess, when connecting the first member and the second member, problems such as the compact cracking starting from the chipping are less likely to occur.

[0015] <2>In the connecting body according to <1> above, the second member may be the compact, and the surface of the second member facing the first member may be the first surface.

[0016] In the configuration of <2> above, the swarf generated by threading the base hole with a tapping screw is disposed in the space surrounded by the recess of the second member and the first member. Therefore, the swarf is sandwiched between the first member and the second member, and it is difficult to form a gap between the first member and the second member.

[0017] <3>In the connecting body according to <1> or <2> above, the screw may be a tapping screw.

[0018] The tapping screw is firmly fixed to the compact while threading the base hole formed in the compact. Therefore, the connection between the first member and the second member by the tapping screw becomes strong. Also, there is no need to form a female screw portion in the base hole of the compact before connecting the first member and the second member, and the productivity of the connecting body is improved.

[0019] <4>In the connecting body according to any one of <1> to <3> above, the relative density of the compact may be 85% or more.

[0020] If the relative density of the compacted molded body is 85% or higher, cracks or chips are less likely to occur in the compacted molded body during the manufacturing of the connected body. In particular, even when the first and second members are connected by tapping screws, cracks or chips are less likely to occur in the compacted molded body due to the tapping screws.

[0021] <5> the above <1> from <4> In the connected body described in any of the above, the compacted body contains soft magnetic powder, the soft magnetic powder is an aggregate of soft magnetic particles having an insulating coating on its surface, and the soft magnetic particles may be at least one selected from the group consisting of pure iron, Fe-Si-Al alloy, Fe-Si alloy, Fe-Al alloy, and Fe-Ni alloy.

[0022] Compacted bodies containing soft magnetic powder are used, for example, as cores for rotating electric machines or reactors. Because compacted bodies containing soft magnetic powder have sufficient strength, cracks or chips are less likely to occur in the compacted body even when it is connected to other components with screws.

[0023] <6> the above <1> from <5> In the connecting body described in any of the above, the inner circumferential surface of the recess is provided with an inclined surface connected to the first surface, and the angle between the extended surface, which extends the inclined surface outward from the first surface, and the first surface may be less than 90°.

[0024] The recess having the above-described inclined surface is a recess that gradually widens from the opening of the first hole towards the opening of the recess along the axis of the first hole. If the angle between the extended surface of the inclined surface and the first surface is less than 90°, it is easier to remove the mold used to form the recess when manufacturing the compacted product.

[0025] <7> the above <1> from <6> In the connecting body described in any of the above, the depth of the recess may be 0.1 mm or more and 3.0 mm or less.

[0026] The depth of the recess is the distance from the first surface to the deepest part of the recess. If the depth of the recess is 0.1 mm or more, burrs generated when the base hole of the compacted molded body is threaded can be easily contained within the recess. If the depth of the recess is 3.0 mm or less, the actual portion of the compacted molded body will not be reduced too much by the recess. Also, if the depth of the recess is 3.0 mm or less, the strength of the part of the mold used to form the compacted molded body that corresponds to the recess will not be easily reduced.

[0027] <8> the above <1> from <7> In the connecting body described in any of the above, the inner circumferential surface of the recess may have a bottom surface parallel to the first surface.

[0028] If the recess has a bottom surface parallel to the first surface, the screw is less likely to tilt when connecting the first and second members with a screw. <8> Unlike the previous configuration, if the recess consists only of an inclined surface, when connecting the first and second members with screws, the screws may be guided by the inclined surface, causing the screws to tilt.

[0029] <9> the above <1> from <8> In the connecting body described in any of the above, the second member is the core of the stator of a rotating electric machine, the first member is a case for housing the stator, and the core may be made of the powder-molded body.

[0030] the above <9> This configuration allows the stator to be securely fixed to the case. Because the stator is less likely to move relative to the case, the operation of the rotating electric machine becomes more stable.

[0031] <10> the above <1> from <8> In the connecting body described in any of the above, the second member is a tooth provided on the core of the stator of a rotating electric machine, the first member is a yoke provided on the core, and the teeth may be made of the powder-molded body.

[0032] The yoke is positioned on the end face of the teeth opposite to the end face facing the rotor of the rotating electric machine. <10> In this configuration, the teeth and yoke are manufactured independently, making it easier to produce the teeth and yoke together than to manufacture a single, complex-shaped component.

[0033] <11> the above <1> from <8> In the connecting body described in any of the above, the second member is a tooth provided on the core of the stator of a rotating electric machine, the first member is a flange member disposed on the end face of the tooth, and the tooth may be made of the powder-molded body.

[0034] The flange member is positioned on the end face of the teeth that faces the rotor. <11> In this configuration, the teeth and the flange are manufactured independently, making it easier to manufacture the teeth and yoke compared to manufacturing a complex-shaped component in which the teeth and flange are integrated.

[0035] <12> The powder compacted body of the present disclosure is a powder compacted body connected to another member by a screw, comprising: a first surface configured to face the other member or the head of the screw when connected to the other member; a recess formed on the first surface; and a base hole extending from the recess and configured such that the shaft portion of the screw is positioned when connected to the other member. The opening area of ​​the recess is larger than the opening area of ​​the base hole, and the inner circumferential surface of the recess does not have cutting marks.

[0036] The compacted body of the present disclosure is one of the constituent materials of the connecting body of the present disclosure. The compacted body of the present disclosure may be a first member or a second member in the connecting body of the present disclosure. Furthermore, the base hole of the compacted body of the present disclosure becomes a first hole in the connecting body of the present disclosure where a screw is positioned.

[0037] <13> The method for manufacturing a compacted powder article described herein is as described above. <12> The recess in the compacted molded body described above is formed by mold molding used to manufacture the compacted molded body.

[0038] the above <13> Unlike the above configuration, when the recess is formed by cutting, there is a risk that the edge of the recess opening may chip due to tensile stress during cutting. On the other hand, when the recess of the powder compacted body is formed by die molding, <13> This configuration makes it less likely for chipping to occur at the edges of the recessed openings.

[0039] Furthermore, by forming the recesses in the powder compacted body using mold molding, the production process for the powder compacted body can be reduced compared to forming the recesses by machining. As a result, the productivity of the connected body including the powder compacted body is improved.

[0040] <14> the above <13> In the method for manufacturing a compacted powder product described above, the base hole may be formed by drilling after the mold molding.

[0041] When the base hole of a powder compact is formed by die molding, there is a risk of variations in the density of the powder compact near the base hole. Also, the number of mold parts increases by the amount of the core corresponding to the base hole. If the inner diameter of the base hole is narrow, the strength of the core corresponding to the base hole is easily reduced, and there is a risk of the core being damaged during die molding. On the other hand, when the base hole is formed by drilling, <12> In this configuration, the density of the entire compacted body is easily made uniform. Here, since the base hole is formed from the position of the recess, the burrs generated by drilling are contained in the recess. Therefore, the burrs generated by drilling do not pose a problem during the manufacturing of the connected body.

[0042] <15> the above <14> In the method for manufacturing a compacted powder body described above, a build-up portion protruding from the bottom surface of the recess may be formed by the mold molding, and the entire build-up portion may be removed by the drilling.

[0043] By forming a build-up portion that protrudes from the bottom surface of the recess during the mold molding of the powder compact, differences in molding pressure are less likely to occur between the parts with recesses and the parts without recesses. Therefore, the density of the entire powder compact is more easily made uniform.

[0044] [Details of the embodiments of this disclosure] Specific examples of the connectives, compacted bodies, and methods for manufacturing compacted bodies of the present disclosure will be described below with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. The dimensions of the members shown in each drawing are represented for illustrative purposes only and do not necessarily represent actual dimensions. The present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims as shown in the claims.

[0045] <Embodiment 1> ≪Overall Structure≫ The connecting body 1 in this example comprises a first member 11, a second member 12 positioned adjacent to the first member 11, and a tapping screw 13 connecting the first member 11 and the second member 12. The tapping screw 13 penetrates the first member 11 to the second member 12 and is screw-connected to the second member 12. In this example, the second member 12 is a compacted molded body 2, and the first member 11 is an uncompacted molded body 3. One of the features of the connecting body 1 in this example lies in the configuration of the compacted molded body 2. The various components of the connecting body 1 in this example will be described in detail below.

[0046] Tapping screws The tapping screw 13 comprises a shaft portion 13S and a head portion 13H. A male threaded portion is formed on the outer circumference of the shaft portion 13S. The head portion 13H may have a tool hole for inserting a screwdriver or the like. The type of tapping screw 13 is not particularly limited. For example, the tapping screw 13 may be of type B-0 or type B-1. A type B-1 tapping screw 13 is a tapping screw 13 in which a cutting edge groove is formed at its tip.

[0047] In the connecting body 1 of this example, a washer 14, which is a separate component from the tapping screw 13, is placed between the head 13H and the first member 11. Alternatively, a tapping screw 13 in which the washer 14 is integrated with the head 13H may be used. In that case, the head 13H will be in contact with the first member 11.

[0048] ≪Filled Powder Products≫ The compacted body 2 constituting the second member 12 includes, for example, soft magnetic powder. The soft magnetic powder is an aggregate of soft magnetic particles. The soft magnetic particles are, for example, at least one selected from the group consisting of pure iron, Fe (iron)-Si (silicon)-Al (aluminum) alloys, Fe-Si alloys, Fe-Al alloys, and Fe-Ni (nickel) alloys. The soft magnetic particles may have an insulating coating on their surface. The insulating coating on the surface of the soft magnetic particles provides electrical insulation between them. When the compacted body 2 is used as a core for a rotating electric machine or the like, the insulating coating can reduce eddy current losses in the core. The insulating coating is, for example, a phosphate coating or a silica coating.

[0049] The average particle size of the soft magnetic particles is, for example, 10 μm to 400 μm. If the average particle size of the soft magnetic particles is 10 μm or more, the increase in hysteresis loss in the compacted body 2 can be reduced when the compacted body 2 is used as a core for a rotating electric machine or the like. If the average particle size of the soft magnetic particles is 400 μm or less, the eddy current loss of the compacted body 2 generated in the high-frequency range can be reduced when the compacted body 2 is used as a core for a rotating electric machine or the like. The average particle size of the soft magnetic particles may also be, for example, 10 μm to 300 μm or 40 μm to 260 μm. Here, the average particle size refers to the particle size of the particles whose mass sum from the smallest particle size to the largest particle size in the particle size histogram reaches 50% of the total mass, i.e., the 50% particle size.

[0050] The relative density of the compacted body 2 should preferably be 85% or higher. Higher density makes the compacted body 2 less prone to cracking or chipping. The relative density of the compacted body 2 may be 90% or higher, 93% or higher, or 95% or higher. The relative density of the compacted body 2 is the value obtained by dividing the apparent density of the compacted body 2 by its true density. The apparent density is obtained by measuring the volume of the compacted body 2 using the Archimedes method and dividing the mass of the compacted body 2 by the measured volume.

[0051] The compacted body 2 comprises a first surface 21, a recess 23, and a first hole 25. In this example, the first surface 21 is the surface facing the first member 11. The recess 23 is a depression formed in the first surface 21. The first hole 25 is a blind hole extending from the recess 23. The shaft portion 13S of the tapping screw 13 is positioned in the first hole 25. The first hole 25 may also be a through hole opening into the first surface 21 and the second surface 22. The second surface 22 is the surface opposite to the first surface 21.

[0052] The shaft portion 13S of the tapping screw 13 is screw-connected to the first hole 25. The first hole 25 is formed by screwing the tapping screw 13 into a base hole 24 that is pre-formed in the compacted molded body 2. The base hole 24 in this example is generally called a prepared hole. The base hole 24 has an inner circumferential surface composed of a cylindrical surface. This base hole 24 is threaded with the tapping screw 13 to form a female thread portion 24f. The base hole 24 with the female thread portion 24f is the first hole 25.

[0053] A gap is formed between the bottom surface of the first hole 25 and the tip of the shaft portion 13S. Therefore, the tip of the shaft portion 13S does not apply stress to the bottom surface of the first hole 25, making the compacted powder molded body 2 less likely to crack.

[0054] The bottom of the first hole 25 may be tapered, as shown in Figure 1. In this case, the tip of the shaft portion 13S of the tapping screw 13 is less likely to come into contact with the bottom surface of the first hole 25, and even if the tip of the shaft portion 13S comes into contact with the bottom surface of the first hole 25, the compacted molded body 2 is less likely to crack. The angle φ formed by the tapered shape of the bottom is, for example, 85° to 145°. The angle φ is the angle between the left-sloping surface and the right-sloping surface of the bottom that straddle the axis in a cross-section containing the axis of the shaft portion 13S.

[0055] As shown in Figure 2, the recess 23 is formed to surround the opening 25o of the first hole 25. The opening area of ​​the recess 23 is larger than the opening area of ​​the first hole 25. In other words, in a top view, the opening 25o of the first hole 25 is located inside the opening 23o of the recess 23.

[0056] The opening 23o of the recess 23 is sized to fit inside the outer contour of the washer 14 (Figure 1) when viewed from above. In this case, the washer 14 will not fall into the recess 23. If the washer 14 is not used in the connecting body 1, the opening 23o is sized to fit inside the outer contour of the head 13H of the tapping screw 13.

[0057] The inner circumferential surface 230 of the recess 23 is a compression-molded surface without cutting marks. The absence of cutting marks on the inner circumferential surface 230 can be confirmed by visual inspection. Such a recess 23 can be formed by pressure molding, as will be described later. The opening 23o of the recess 23 formed without using cutting does not have any chipping caused by cutting. Furthermore, since the recess 23 is formed without cutting, the productivity of the compacted molded body 2 is high.

[0058] The arithmetic mean roughness Ra of the inner circumferential surface 230 of the recess 23 is, for example, 3.2 μm or less. The arithmetic mean roughness Ra conforms to JIS B 0601:2013. When the recess 23 is formed by machining, the arithmetic mean roughness Ra of the inner circumferential surface 230 of the recess 23 tends to exceed 3.2 μm. In other words, an arithmetic mean roughness Ra of 3.2 μm or less on the inner circumferential surface 230 is one indicator that the recess 23 was formed by pressure molding.

[0059] The inner circumferential surface 230 of the recess 23 in this example comprises a bottom surface 231 parallel to the first surface 21 and an inclined surface 232 connecting the first surface 21 and the bottom surface 231. The inclined surface 232 is tilted so as it moves from the first hole 25 toward the first surface 21 along the axis 25s of the first hole 25, it gradually moves away from the axis 25s.

[0060] The bottom surface 231 is configured to prevent the axis of the tapping screw 13 from tilting when screwing in the tapping screw 13, as will be explained later in the manufacturing method of the connecting body 1. The inclined surface 232 is configured to make it easier to remove the powder compacted body 2 from the mold 9 (see Figure 3) when forming the recess 23 by mold molding, as will be explained later in the manufacturing method of the powder compacted body 2. The angle θ between the extended surface, which is an extension of this inclined surface 232, and the first surface 21 is less than 90°. The smaller the angle θ, the easier it is to remove the powder compacted body 2 from the mold 9. The angle θ may be, for example, 80° or less, or 70° or less. Regarding the lower limit of the angle θ, the angle θ may be, for example, 30° or more, or 45° or more. In this example, the angle θ is 70°.

[0061] Unlike this example, the inner wall surface of the recess 23 may be a wall surface perpendicular to the bottom surface 231. In that case, the angle θ between the extended surface obtained by extending the wall surface and the first surface 21 is 90°.

[0062] As already mentioned, when the tapping screw 13 is screwed into the base hole 24, the tapping screw 13 bites into the inner circumferential surface of the base hole 24, and a portion of the inner circumferential surface is removed. This removed material protrudes as a burr 4 from the opening 25o of the first hole 25. In this example, since a recess 23 is formed so as to surround the opening 25o, the burr 4 is located within the recess 23. The burr 4 located within the recess 23 is not sandwiched between the first member 11 and the second member 12, as shown in Figure 1. Therefore, the first member 11 and the second member 12 can be firmly connected without forming a large gap between them. The firmly connected first member 11 and the second member 12 are unlikely to come apart, and the connected state is maintained over a long period of time.

[0063] The depth D of the recess 23 in which the burr 4 is contained is, for example, 0.1 mm or more and 3.0 mm or less. The depth D of the recess 23 having a bottom surface 231 is the distance from the first surface 21 to the deepest point of the recess 23, which in this example is the distance from the first surface 21 to the bottom surface 231. If the depth D of the recess 23 is 0.1 mm or more, the burr 4 is easily contained within the recess 23. If the depth D of the recess 23 is 3.0 mm or less, the solid portion of the compacted molded body 2 is not reduced too much. The strength of the part of the mold 9 (see Figure 3) for forming the compacted molded body 2 that corresponds to the recess 23 is not easily reduced. The depth D of the recess 23 may also be, for example, 0.3 mm or more and 1.0 mm or less.

[0064] The length L1 from the edge of the first hole 25 to the edge of the opening 23o of the recess 23 is, for example, 0.2 mm or more and 3.0 mm or less. If the length L1 is 0.2 mm or more, it is easy to insert the tapping screw 13 into the base hole 24 when manufacturing the connecting body 1. If the length L1 is 3.0 mm or less, the recess 23 does not become too large, and the first member 11 and the second member 12 have a sufficient contact area, so the connection between the first member 11 and the second member 12 is easily stabilized. Here, the smaller the angle θ formed above, the longer the length L1 becomes. Therefore, the upper limit of the length L1 can also be considered to define the lower limit of the angle θ formed. If the angle θ formed is greater than or equal to the lower limit value mentioned above, not only is it easier to remove the compacted molded body 2 from the mold 9, but the length L1 does not become too large even if the depth D of the recess 23 is increased.

[0065] <<Uncompacted Powdered Products>> The non-compacted molded body 3 constituting the first member 11 can be anything other than the compacted molded body 2. For example, the non-compacted molded body 3 may be metal or resin. The non-compacted molded body 3 has a through hole 35 through which the shaft portion 13S of the tapping screw 13 is inserted. The inner diameter of the through hole 35 is larger than the inner diameter of the shaft portion 13S. In other words, the through hole 35 is a through hole through which the tapping screw 13 passes. In this example, the through hole 35 does not have a female thread portion on its inner circumferential surface, but has an inner circumferential surface composed of a cylindrical surface. Unlike this example, the through hole 35 may be a screw hole having a female thread portion on its inner circumferential surface. In that case, a part of the shaft portion 13S is screw-connected to the through hole 35.

[0066] ≪Method for manufacturing compacted powder products≫ The compacted body 2, which constitutes the second member 12, is manufactured by mold molding using the mold 9 shown in Figure 3. The mold 9 comprises a die 91, a lower punch 92, and an upper punch 93. When manufacturing the compacted body 2 using this mold 9, first the lower punch 92 is fitted into the die 91. Soft magnetic powder is filled into the cavity surrounded by the inner circumferential surface of the die 91 and the upper surface of the lower punch 92. Finally, the upper punch 93 is fitted into the die 91 from above, and the upper punch 93 is moved downward, compressing the soft magnetic powder between the lower punch 92 and the upper punch 93. The compression direction is the direction of movement of the upper punch 93, i.e., downward. The compacted body 2 is manufactured by this compression. Here, a convex portion 93p is formed on the lower surface of the upper punch 93 to form the recess 23 of the compacted body 2. In this example, a recess is formed on the end face of the convex portion 93p.

[0067] Figure 4 is a magnified view of the vicinity of the recess 23 of the compacted body 2. The first surface 21 of the compacted body 2 has a recess 23 formed on it, onto which the shape of the convex portion 93p of the upper punch 93 has been transferred. In this example, the recess 23 has an inclined surface 232, so when the upper punch 93 is moved upward to remove the compacted body 2 from the mold 9, the upper punch 93 easily separates from the compacted body 2.

[0068] In this example, a recess formed on the end face of the convex portion 93p creates a build-up portion 23b that protrudes from the bottom surface 231 at the position of the bottom surface 231 of the recess 23 of the compacted body 2. By forming the build-up portion 23b, it is less likely that there will be a difference in molding pressure along the compression direction between the part with the recess 23 and the part without the recess 23 during mold molding. Therefore, the density of the entire compacted body 2 is more likely to be uniform. The protrusion height of the build-up portion 23b from the bottom surface 231 is, for example, 50% or more and 100% or less of the depth D of the recess 23. The above protrusion height may also be 60% or more, 70% or more, or 80% or more of the depth D.

[0069] Unlike this example, the protrusion 93p for forming the recess 23 of the compacted molded body 2 may be formed on the lower punch 92.

[0070] Next, a base hole 24 extending from the bottom surface 231 of the recess 23 is formed by drilling. In Figure 4, the formation area of ​​the base hole 24 is shown by a dashed line. The inner diameter of the base hole 24 is smaller than the outer diameter of the tapping screw 13. The formation area of ​​the base hole 24 is smaller than the bottom surface 231. Therefore, the bottom surface 231 remains, encircling the opening of the base hole 24 in an annular shape. When forming this base hole 24, the entire build-up portion 23b is removed. Unlike this example, the base hole 24 may also be formed by mold forming, but in that case, the density near the base hole 24 in the compacted body 2 tends to decrease compared to other parts. When the base hole 24 is formed after mold forming, as in this example, the density near the base hole 24 does not decrease significantly compared to other parts.

[0071] When the base hole 24 is formed by drilling, a burr (not shown) protrudes from the opening 24o of the base hole 24. Since this burr is located in the recess 23, it does not need to be removed. The burr may be removed, but in that case, care must be taken to prevent chipping from occurring on the edge of the opening 24o of the base hole 24.

[0072] The compacted body 2 may be heat-treated before or after drilling. By removing the distortion of the compacted body 2 through heat treatment, a compacted body 2 with low loss can be manufactured. In addition, heat treatment makes it easier to remove binders or lubricants contained in the compacted body 2. The heat treatment temperature is, for example, between 400°C and 900°C.

[0073] ≪Method for manufacturing the connected body≫ As shown in Figure 1, a compacted body 2 manufactured by mold molding and a non-compacted body 3 prepared separately from the compacted body 2 are stacked on top of each other, and a tapping screw 13 is inserted through the through hole 35 of the non-compacted body 3 and screwed into the base hole 24 of the compacted body 2. At this time, because a bottom surface 231 is formed in the recess 23, the tip of the shaft portion 13S of the tapping screw 13 is less likely to tilt with respect to the axis of the base hole 24, and the shaft portion 13S is easily guided straight into the base hole 24.

[0074] During the process of screwing the tapping screw 13 into the base hole 24, a burr 4 is generated. This burr 4 is located in the recess 23 and is not sandwiched between the first member 11, which is made of the non-compacted molded body 3, and the second member 12, which is made of the compacted molded body 2. In this way, by using the compacted molded body 2 having the recess 23, a connected body 1 is manufactured in which the first member 11 and the second member 12 are firmly connected.

[0075] <Embodiment 2> The connecting body 1 according to Embodiment 2 will be described with reference to Figure 5. In the connecting body 1 of this example, the first member 11 is a compacted molded body 2, and the second member 12 is an uncompacted molded body 3.

[0076] In this example, the first surface 21 of the compacted body 2 faces the head 13H of the tapping screw 13. The recess 23 formed on the first surface 21 also naturally faces the head 13H. The first hole 25 is a through hole that penetrates from the first surface 21 to the second surface 22. On the inner circumferential surface of the first hole 25, a female threaded portion 24f is formed along the entire length of the first hole 25. This female threaded portion 24f is formed by the tapping screw 13. In this connecting body 1 as well, the burr 4 generated by the tapping screw 13 is located within the recess 23. The burr 4 is not caught between the first member 11, which is made of the compacted body 2, and the head 13H, and the head 13H firmly applies even pressure to the first surface 21. As a result, the first member 11 and the second member 12 are firmly connected, and the connection is unlikely to loosen.

[0077] A screw hole 36 is formed in the second member 12, which is made of an uncompacted powder molded body 3. A tapping screw 13 is screw-connected to this screw hole 36. The screw hole 36 may have a female thread portion that has been formed in advance by a tap, or it may have a female thread portion that has been formed by the tapping screw 13.

[0078] <Embodiment 3> The connecting body 1 according to Embodiment 3 will be described with reference to Figure 6. In the connecting body 1 of this example, both the first member 11 and the second member 12 are compacted powder molded bodies 2.

[0079] The first surface 21 and recess 23 of the compacted body 2 constituting the first member 11 face the head 13H of the tapping screw 13. The first hole 25 of the first member 11 is a through hole, and a female thread portion 24f is formed on its inner circumferential surface along the entire length of the first hole 25. The first surface 21 and recess 23 of the compacted body 2 constituting the second member 12 face the second surface 22 of the first member 11. The first hole 25 of the second member 12 is a blind hole, and a female thread portion 24f is formed on a part of its inner circumferential surface. The female thread portions 24f in the first holes 25 of the first member 11 and the second member 12 are formed by the tapping screw 13. In this configuration, the burrs 4 generated on each compacted body 2 by the tapping screw 13 are placed in the recesses 23 of the compacted body 2 where the burrs 4 were generated. Therefore, the first member 11 and the second member 12 are firmly connected, and the connection is unlikely to loosen.

[0080] <Embodiment 4> The connecting body 1 according to Embodiment 4 will be described with reference to Figure 7. In the connecting body 1 of this example, the first member 11 is a compacted molded body 2, and the second member 12 is an uncompacted molded body 3. The screw 15 connecting the first member 11 and the second member 12 is not a self-tapping screw. The screw hole 36 of the second member 12 has a female threaded portion that has been machined into a pilot hole with a tap. The first member 11 and the second member 12 are connected by screwing the shaft portion 15S of the screw 15 into this screw hole 36.

[0081] The first member 11 facing the head 15H of the screw 15 is a compacted body 2. The inner diameter of the first hole 25 in the compacted body 2 is a through hole larger than the outer diameter of the shaft portion 15S of the screw 15. No female threads are formed on the inner surface of the first hole 25. This first hole 25 is the base hole 24 itself, formed by drilling during the manufacturing of the compacted body 2. The burrs 4 located in the recess 23 were generated during drilling.

[0082] In this example, the connecting body 1 is manufactured by connecting the compacted body 2 and the uncompacted body 3 without removing the burrs 4 that are generated when forming the base hole 24 in the compacted body 2. Because there is no need to remove the burrs 4, the productivity of the connecting body 1 is high.

[0083] <Embodiment 5> As a modified example of Embodiment 2, which refers to Figure 5, a connecting body 1 according to Embodiment 5, in which the compacted molded body 2 is equipped with a storage section 29, will be described based on Figure 8. In the connecting body 1 of this example, the first member 11 is the compacted molded body 2, and the second member 12 is the uncompacted molded body 3.

[0084] The compacted powder body 2 constituting the first member 11 has a storage section 29 in which the entire head 13H of the tapping screw 13 is housed. In this case, the bottom surface of the storage section 29 becomes the first surface 21. In the connecting body 1 of this example as well, the burrs 4 generated by the tapping screw 13 are placed in the recess 23.

[0085] <Embodiment 6> Embodiment 6 describes an example in which the configuration of the connecting body 1 shown in Embodiment 1 is applied to the rotating electric machine 5, based on Figure 9. The rotating electric machine 5 may be a generator or an electric motor.

[0086] The rotating electric machine 5 in this example comprises a rotor 6, a stator 7, and a case 8. The rotating electric machine 5 in this example is an axial gap type rotating electric machine 5 in which the rotor 6 and the stator 7 are aligned in a direction along the rotation axis of the rotor 6.

[0087] Rotor The rotor 6 comprises a plurality of flat magnets 61 and an annular retaining plate 60 that supports these magnets 61. The retaining plate 60 is fixed to the shaft 50 and rotates with the shaft 50. The magnets 61 are embedded in the retaining plate 60. The magnets 61 are arranged at intervals around the shaft 50. The magnetization directions of adjacent magnets 61 in the direction of rotation of the shaft 50 are opposite to each other.

[0088] ≪Stata≫ The stator 7 comprises a core 70 and a plurality of coils 75. The core 70 comprises an annular yoke 71 and a plurality of teeth 72. The teeth 72 may have a flange 72f (Figure 10) as shown in Embodiment 7 described later. The plurality of teeth 72 protrude from one surface of the yoke 71. A coil 75 is arranged on each tooth 72. The rotating electric machine 5 in this example comprises two stators 7. The end faces of the teeth 72 of the first stator 7 and the end faces of the teeth 72 of the second stator 7 face each other across the rotor 6. The core 70 in this example is formed from a compacted powder molded body 2.

[0089] ≪Case≫ Case 8 houses the rotor 6 and the stator 7. Case 8 is made of a non-magnetic material, such as an aluminum alloy. The shaft 50 connected to the rotor 6 passes through case 8. A bearing 51 is positioned between the outer surface of the shaft 50 and case 8.

[0090] In the rotating electric machine 5 of this example, the core 70 formed by the compacted powder molded body 2 and the case 8 formed by the uncompacted powder molded body 3 are connected by tapping screws 13. The burrs 4 (Figure 1) generated by the tapping screws 13 are not trapped between the core 70 and the case 8. As a result, the core 70 is firmly fixed to the case 8, and the rotation of the rotor 6 is stable.

[0091] The rotating electric machine 5 in this example is a single-rotor, double-stator type rotating electric machine. The rotating electric machine 5 to which the configuration of the connecting body 1 is applied may also be other types of rotating electric machines, such as a double-rotor, single-stator type rotating electric machine.

[0092] <Embodiment 7> Embodiment 7 describes a rotating electric machine 5 equipped with a different connecting body 1 than that of Embodiment 6, based on Figure 10. Figure 10 shows only the left half of the rotating electric machine 5, and the case is not shown.

[0093] The teeth 72 of the core 70 in this example are equipped with flanges 72f. The flanges 72f protrude laterally from the ends of the teeth 72 on the side surface of the teeth 72. The flanges 72f improve the magnetic properties of the rotating electric machine 5.

[0094] In this example, the core 70 is manufactured with the yoke 71 and teeth 72 independently produced. The yoke 71 and teeth 72 are connected by tapping screws 13 to form the connecting body 1 of embodiment 7. In this case, the yoke 71 is the first member 11 and the teeth 72 is the second member 12.

[0095] In this example, the yoke 71 is an uncompacted molded body 3, and the teeth 72 are a compacted molded body 2. The uncompacted molded body 3 is, for example, an SS400 plate, a SUS plate, or a laminated steel plate. Unlike this example, both the yoke 71 and the teeth 72 may be compacted molded bodies 2, or the yoke 71 may be a compacted molded body 2 and the teeth 72 may be an uncompacted molded body 3.

[0096] <Embodiment 8> Embodiment 8 describes a rotating electric machine 5 equipped with a different connecting body 1 than those in Embodiments 6 and 7, based on Figure 11. Figure 11 shows only the left half of the rotating electric machine 5, and the case is not shown.

[0097] In this example, the core 70 has a yoke 71 and teeth 72 integrated together, and further includes a flange member 73 positioned on the end face of the teeth 72. The flange member 73 is a plate-shaped member and has the function of the end of the teeth 72 and the flange 72f in Figure 10 of Embodiment 7.

[0098] In this example, the core 70 is manufactured with teeth 72 and flange member 73 independently produced. The teeth 72 and flange member 73 are connected by tapping screws 13 to form the connecting body 1 of embodiment 8. In this case, the flange member 73 is the first member 11, and the teeth 72 is the second member 12.

[0099] In Embodiment 8, the yoke 71 and the teeth 72 may be independent components. In that case, the yoke 71 and the teeth 72 may be connected by tapping screws 13, as in the configuration of Embodiment 7.

[0100] <Note> The configuration of the connecting body of this disclosure can be applied to the connection of injection-molded bodies. Specifically, the connecting body comprises a first member, a second member positioned in contact with the first member, and a screw that penetrates the first member and reaches the second member, connecting the first member and the second member, wherein at least one of the first member and the second member is an injection-molded body. The injection-molded body comprises a first surface facing the head of the first member or the screw that is in contact with the injection-molded body, a recess formed on the first surface, and a first hole extending from the recess in which the shaft of the screw is positioned. The opening area of ​​the recess is larger than the opening area of ​​the first hole, and the inner circumferential surface of the recess has no machining marks.

[0101] The injection-molded body is, for example, a composite material or resin molded body containing resin and powder. In the composite material, the powder is dispersed in the resin. The powder is, for example, soft magnetic powder. With the configuration described above, the burr that protrudes from the opening of the first hole when the first member and the second member are connected can be placed in the recess, allowing the first member and the second member to be securely connected. [Explanation of symbols]

[0102] 1 Concatenation 2. Compacted powder body 3. Uncompacted molded body 4 Return 5 Rotating Electric Machines 6 rotors 7 Status 8 cases 9 molds 11 First component 12 Second Member 13 Tapping screws 13H head 13S Shaft 14 washers 15 screws 15H head 15S shaft part 21 Front page 22 Second side 23 Recess 23b Meat buildup section 23o opening 24 base holes 24f Female thread section 24o opening 25 First hole 25o opening 25s axis 29 Storage compartment 35 Through hole 36 screw holes 50 shaft 51 Bearings 60 Holding plate 61 Magnets 70 cores 71 York 72 Teeth 72f Tsuba (sword guard) 73. Flange member 75 coils 91 Die 92. Lower punch 93 Upper punch 93p Convex part 230 Inner surface 231 Bottom 232 Slope D Depth L1 Length Angle between θ and φ

Claims

1. First component and A second member is positioned in contact with the first member, A screw that penetrates the first member and reaches the second member, connecting the first member and the second member, is provided. At least one of the first member and the second member is a compacted powder molded body. The compacted powder molded body is The first member that contacts the compacted body or the first surface facing the head of the screw, The recess formed on the first surface, It comprises a first hole extending from the recess and in which the shaft portion of the screw is located, The opening area of ​​the recess is wider than the opening area of ​​the first hole. The inner circumferential surface of the recess does not have any cutting marks. Connector.

2. The second member is the powder compacted body, The connecting body according to claim 1, wherein the surface of the second member facing the first member is the first surface.

3. The connecting body according to claim 1 or claim 2, wherein the screw is a self-tapping screw.

4. The connecting body according to claim 3, wherein the relative density of the compacted molded body is 85% or more.

5. The compacted powder body contains soft magnetic powder, The soft magnetic powder is an aggregate of soft magnetic particles having an insulating coating on its surface. The connecting body according to claim 4, wherein the soft magnetic particles are at least one selected from the group consisting of pure iron, Fe-Si-Al alloy, Fe-Si alloy, Fe-Al alloy, and Fe-Ni alloy.

6. The inner circumferential surface of the recess is provided with an inclined surface connected to the first surface, The connecting body according to claim 1 or claim 2, wherein the angle between the extended surface, which extends the inclined surface outward from the first surface, and the first surface is less than 90°.

7. The connecting body according to claim 1 or claim 2, wherein the depth of the recess is 0.1 mm or more and 3.0 mm or less.

8. The connecting body according to claim 1 or claim 2, wherein the inner circumferential surface of the recess has a bottom surface parallel to the first surface.

9. The second member is the core of the stator of a rotating electric machine, The first member is a case for housing the stator. The connecting body according to claim 1 or claim 2, wherein the core is made of the compacted powder body.

10. The second member is a tooth provided on the core of the stator of a rotating electric machine. The first member is a yoke provided in the core, The connecting body according to claim 1 or claim 2, wherein the teeth are made of the compacted molded body.

11. The second member is a tooth provided on the core of the stator of a rotating electric machine. The first member is a flange member positioned on the end face of the teeth, The connecting body according to claim 1 or claim 2, wherein the teeth are made of the compacted molded body.

12. A compacted powder body connected to other members by screws, A first surface configured to face the other member or the head of the screw when connected to the other member, The recess formed on the first surface, It comprises a base hole extending from the recess and configured such that the shaft portion of the screw is positioned in a state connected to the other member, The opening area of ​​the recess is wider than the opening area of ​​the base hole. The inner circumferential surface of the recess does not have any cutting marks. Compacted powder body.

13. The recess in the compacted body described in claim 12 is formed by mold molding for manufacturing the compacted body. A method for manufacturing a compacted powder body.

14. The method for manufacturing a compacted molded body according to claim 13, wherein the base hole is formed by drilling after the mold forming.

15. The mold forming creates a built-up portion that protrudes from the bottom surface of the recess, The method for manufacturing a compacted molded body according to claim 14, wherein the entire build-up portion is removed by the drilling described above.

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