Connected body, powder molded body, and method for producing powder

Abstract

The invention provides a connected body, a powder compact, and a method for producing the powder compact. In a connected body, even if at least one of a first member and a second member connected by a screw is a powder compact, the first member and the second member are stably connected. The connecting body includes: a first member; a second member disposed so as to be in contact with the first member; and a screw penetrating the first member to reach the second member and connecting the first member and the second member, at least one of the first member and the second member being a powder compact. The powder compact is provided with: a first surface facing the head of the first member or the screw in contact with the powder compact; a recess formed in the first surface; and a first hole which extends from the recess and in which the shaft portion of the screw is disposed. The opening area of the recessed portion is larger than the opening area of the first hole, and the inner peripheral surface of the recessed portion does not have a cutting mark.

Description

Technical Field

[0001] This disclosure relates to a connector, a powder-pressed body, and a method for manufacturing the powder-pressed body. Background Technology

[0002] In recent years, attempts have been made to connect powder-pressed bodies, which are produced by pressing powder, to other components using self-tapping screws. As such a technology, Patent Document 1 discloses a connector obtained by connecting a first component and a second component that are independent of each other using self-tapping screws. At least one of the first component and the second component in this connector is a powder-pressed body.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2020 / 226011 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] If a self-tapping screw is screwed into the bottom hole formed in the powder forming body, the self-tapping screw forms a threaded groove on the inner circumferential surface of the bottom hole. Machining the bottom hole with the self-tapping screw creates a burr. The burr protrudes from the opening of the bottom hole. Here, when the powder forming body is overlapped with other components and a self-tapping screw is screwed in from the other components toward the powder forming body, the burr can become trapped between the powder forming body and the other components, easily creating a gap between them. Additionally, when the powder forming body is overlapped with other components and a self-tapping screw is screwed in from the powder forming body toward the other components, the burr can become trapped between the head of the self-tapping screw and the powder forming body, easily creating a gap between the head and the powder forming body. In either case, the connection between the powder forming body and other components may become unstable due to the burr.

[0008] One of the purposes of this disclosure is to provide a connector in which the first and second components are stably connected even if at least one of the first and second components connected by screws is a pressed powder body.

[0009] Technical solutions for solving technical problems

[0010] The connector disclosed comprises: a first component; a second component configured to engage with the first component; and a screw passing through the first component to the second component, connecting the first component and the second component, wherein at least one of the first component and the second component is a powder-forming body. The powder-forming body comprises: a first surface facing the head of the first component or the screw engaged with the powder-forming body; a recess formed on the first surface; and a first hole extending from the recess for accommodating the shaft portion of the screw. 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 cutting marks.

[0011] Invention Effects

[0012] The connector disclosed herein is a connector in which the first component and the second component are stably connected even if at least one of the first component and the second component is a powder-molded body. Attached Figure Description

[0013] Figure 1 This is a simplified structural diagram of the connector involved in Implementation Method 1.

[0014] Figure 2 yes Figure 1 A magnified view of a portion of the image.

[0015] Figure 3 This is an explanatory diagram illustrating the steps of manufacturing the powder-molded body of the connector involved in Embodiment 1.

[0016] Figure 4 Through Figure 3 The enlarged cross-sectional view of the pressed powder molded body obtained by the mold shown.

[0017] Figure 5 This is a simplified structural diagram of the connector involved in Implementation Method 2.

[0018] Figure 6 This is a simplified structural diagram of the connector involved in Implementation Method 3.

[0019] Figure 7 This is a simplified structural diagram of the connector involved in Implementation Method 4.

[0020] Figure 8 This is a simplified structural diagram of the connector involved in Implementation Method 5.

[0021] Figure 9 This is a simplified structural diagram of the rotary electric motor involved in Embodiment 6.

[0022] Figure 10 This is a simplified structural diagram showing a portion of the rotary electric motor according to Embodiment 7.

[0023] Figure 11 This is a simplified structural diagram showing a portion of the rotary electric motor according to Embodiment 8. Detailed Implementation

[0024] [Description of embodiments of this disclosure]

[0025] In researching the aforementioned technical problems, the inventors of this disclosure conceived of forming a recess in the opening of the bottom hole where a self-tapping screw is disposed in the powder compact. In this case, even if a burr protrudes from the opening of the bottom hole when the self-tapping screw is screwed into it, the burr will be contained within the recess. However, since the powder compact is relatively brittle, if the recess is formed by machining or the like, the edge of the opening of the recess is prone to breakage. Furthermore, the time and effort required to perform machining will reduce the productivity of the powder compact. Based on these insights, the inventors of this disclosure completed the structure of this disclosure. Hereinafter, embodiments of this disclosure will be described.

[0026] <1> The connector disclosed comprises: a first component; a second component configured to engage with the first component; and a screw passing through the first component to the second component, connecting the first component and the second component, wherein at least one of the first component and the second component is a powder-forming body. The powder-forming body comprises: a first surface facing the head of the first component or the screw engaged with the powder-forming body; a recess formed on the first surface; and a first hole extending from the recess for accommodating the shaft portion of the screw. 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 cutting marks.

[0027] The first hole formed in the powder-formed body of the connector is either a threaded hole for threaded engagement with a screw or a through-hole through which the screw passes. In this specification, the hole formed in the powder-formed body before assembly into the connector and used for the shaft portion of the screw during connector manufacturing is called the base hole. No internal thread for threaded engagement with the screw is formed on the inner circumferential surface of this base hole. When a self-tapping screw is screwed into the base hole during connector manufacturing—that is, when the base hole functions as a pilot hole—the inner circumferential surface of the base hole is threaded using the self-tapping screw, forming an internal thread on the inner circumferential surface of the base hole. In this case, the base hole with the internal thread formed during connector manufacturing becomes the first hole in the connector. Here, refer to… Figure 7As shown in Embodiment 4, there may also be cases where the screw connecting the first component and the second component is not a self-tapping screw. In this case, the inner diameter of the base hole is set to be larger than the outer diameter of the screw. During the manufacturing of the connector, the base hole is not threaded; instead, only the shaft portion of the screw is inserted through the base hole. Therefore, the base hole of the powder-formed body directly becomes the first hole of the connector. In the following description, the connection between the first component and the second component via a self-tapping screw will be primarily explained.

[0028] In the above <1> In the connecting body, a screw is mounted from the first component toward the second component. When the first component is a pressed powder molded body, the recess of the first component faces the head of the screw. When the screw connecting the first and second components is a self-tapping screw, burrs generated by threading the base hole are contained within the space surrounded by the recess of the first component and the head of the screw. Therefore, to prevent burrs from being trapped between the first component and the head of the screw, the first and second components are securely connected.

[0029] When the second component is a pressed powder molded body, the recess of the second component faces the first component. When the screw connecting the first and second components is a self-tapping screw, burrs generated by threading the base hole are contained in the space surrounded by the recess of the second component and the first component. Therefore, to prevent burrs from being trapped between the first and second components, the first and second components are securely connected.

[0030] The inner circumferential surface of the recess in the aforementioned connector does not have cutting marks. Cutting marks, also known as tool marks, have a characteristic appearance and can therefore be identified visually. Thus, it can be confirmed by visually inspecting the inner circumferential surface of the recess that there are no cutting marks there. The absence of cutting marks on the inner circumferential surface of the recess indicates that the recess was not formed by cutting, but rather during the pressure forming process of the powder-molded body. In other words, visually inspecting the inner circumferential surface of the recess reveals that it is not a cutting surface formed by cutting, but rather a compression-formed surface with the shape of the mold transferred onto it. When the recess is formed by pressure forming, defects are less likely to occur. If the recess is free of defects, when connecting the first and second components, it is less likely that the powder-molded body will break due to defects.

[0031] <2> In the above <1> In the described connector, the second component may be the powder-forming body, and the surface of the second component facing the first component may be the first surface.

[0032] In the above <2> In this structure, the burrs generated by threading the base hole with self-tapping screws are positioned in the space surrounded by the recess of the second component and the first component. Therefore, it is less likely that the burrs will be trapped between the first and second components, thus preventing a gap from forming between them.

[0033] <3> In the above <1> or <2> The screw described in the connection can also be a self-tapping screw.

[0034] The self-tapping screw securely fixes itself to the powder forming body by threading the hole formed therein. This makes the connection between the first and second components via the self-tapping screw more stable. Furthermore, it eliminates the need to form internal threads in the hole of the powder forming body before connecting the first and second components, thus improving the productivity of the connection.

[0035] <4> In the above <1> to <3> In any of the connectors described herein, the relative density of the pressed powder molded body may be 85% or more.

[0036] If the relative density of the pressed powder molded body is above 85%, it is less likely to crack or break during the manufacturing of the connector. In particular, even when the first part and the second part are connected by self-tapping screws, the pressed powder molded body is less likely to crack or break due to the self-tapping screws.

[0037] <5> In the above <1> to <4> The connector described in any of the above may also be a powder-formed body comprising soft magnetic powder, wherein the soft magnetic powder is an aggregate of soft magnetic particles having an insulating coating on the surface, and the soft magnetic particles are at least one selected from the group consisting of pure iron, Fe-Si-Al alloys, Fe-Si alloys, Fe-Al alloys and Fe-Ni alloys.

[0038] Powder-molded bodies containing soft magnetic powder are used, for example, in the cores of rotating motors or reactors. Because powder-molded bodies containing soft magnetic powder have sufficient strength, they are not prone to cracking or damage even when connected to other components by screws.

[0039] <6> In the above <1> to <5> In any of the connectors described herein, the inner peripheral surface of the recess may have an inclined surface connected to the first surface, and the angle between the extended surface obtained by extending the inclined surface outward beyond the first surface and the first surface is less than 90°.

[0040] The recess with the aforementioned inclined surface has a shape that gradually widens from the opening of the first hole toward 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°, the mold used to form the recess can be easily removed when manufacturing the powder-pressed molded body.

[0041] <7> In the above <1> to <6> In any of the connectors described herein, the depth of the recess may be 0.1 mm or more and 3.0 mm or less.

[0042] 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 by threading the base hole of the powder compact are easily accommodated within the recess. If the depth of the recess is 3.0 mm or less, the solid portion of the powder compact will not be excessively reduced due to the recess. Furthermore, if the depth of the recess is 3.0 mm or less, the strength of the portion of the mold used to form the powder compact is less likely to be reduced.

[0043] <8> In the above <1> to <7> In any of the connectors described herein, the inner peripheral surface of the recess may have a bottom surface parallel to the first surface.

[0044] If the recess has a bottom surface parallel to the first surface, the screw is less likely to tilt when connecting the first component and the second component with a screw. If it is similar to the above... <8> If the structure is different and the recess is only composed of inclined surfaces, then when the first part and the second part are connected by screws, the screws are guided by the inclined surfaces and the screws may tilt.

[0045] <9> In the above <1> to <8> In any of the connecting bodies described herein, the second component may be the iron core of the stator of a rotary motor, the first component may be a housing for receiving the stator, and the iron core may be composed of the powder-pressed molding body.

[0046] According to the above <9> The structure securely fixes the stator to the housing. By making the stator relatively immobile relative to the housing, the operation of the rotary motor is stabilized.

[0047] <10> In the above <1> to <8> In any of the connecting bodies described herein, the second component may be a tooth of the stator core of a rotary motor, and the first component may be a magnetic yoke of the stator core, wherein the tooth is formed by the powder-pressed body.

[0048] The magnetic yoke is positioned on the end face of the teeth opposite the end face of the rotor of the rotating electric motor. In the above... <10> In this structure, since the teeth and yoke are made independently, it is easier to manufacture the teeth and yoke compared to making complex-shaped components where the teeth and yoke are made as one piece.

[0049] <11> In the above <1> to <8> In any of the connecting bodies described herein, the second component may be a tooth of the stator core of a rotary motor, and the first component may be a flange component disposed on the end face of the tooth, wherein the tooth is formed by the powder forming body.

[0050] The flange component is positioned on the end face of the tooth facing the rotor. In the above... <11> In this structure, since the teeth and flange components are manufactured independently, it is easier to manufacture the teeth and flange components compared to manufacturing complex-shaped components where the teeth and flanges are integrated.

[0051] <12> The powder forming body disclosed herein is a powder forming body connected to other components by screws, comprising: a first surface configured to face the other component or the head of the screw when the powder forming body is connected to the other component; a recess formed on the first surface; and a base hole extending from the recess and configured to accommodate the shaft portion of the screw when the powder forming body is connected to the other component. The opening area of ​​the recess is larger than the opening area of ​​the base hole, and the inner circumferential surface of the recess has no cutting marks.

[0052] The powder-pressed molded body disclosed herein is one of the constituent materials of the connector of this disclosure. The powder-pressed molded body of this disclosure can serve as either a first component or a second component in the connector of this disclosure. Furthermore, the base hole of the powder-pressed molded body of this disclosure serves as a first hole in the connector of this disclosure for the placement of screws.

[0053] <13> The method for manufacturing the pressed powder molded article disclosed herein involves manufacturing the above-mentioned... <12> The mold used to form the powder compact is used to form the recess of the powder compact.

[0054] In relation to the above <13> When the recess is formed by machining due to differences in structure, tensile stress during machining may cause edge damage to the opening of the recess. On the other hand, in the case where the recess of the powder-pressed body is formed by die forming, the aforementioned... <13> In the structure, the edges of the opening of the concave part are less prone to damage.

[0055] Furthermore, by forming the recesses of the powder-pressed body using a mold, the number of production steps for the powder-pressed body can be reduced compared to forming the recesses using machining. Therefore, the productivity of connectors, including the powder-pressed body, is improved.

[0056] <14> In the above <13> In the described method for manufacturing the pressed powder molded body, the basic hole may also be formed by drilling after the mold is formed.

[0057] If the base hole of the powder-pressed body is formed by molding, the density of the powder-pressed body near the base hole may deviate. Furthermore, the increased number of mold components results in a larger amount of core corresponding to the base hole. When the inner diameter of the base hole is small, the strength of the core corresponding to the base hole is easily reduced, potentially damaging the core during molding. On the other hand, the aforementioned method of forming the base hole by drilling... <14> In this structure, the overall density of the pressed powder molded body is easily homogenized. Here, since the pores are formed from the recessed areas, the burrs generated by drilling are contained within the recesses. Therefore, the burrs generated by drilling do not pose a problem when manufacturing the connector.

[0058] <15> In the above <14> In the described method for manufacturing the pressed powder molded body, a thickened portion protruding from the bottom surface of the recess can also be formed by forming the mold, and the entire thickened portion can be removed by drilling.

[0059] By forming a thickened portion protruding from the bottom surface of the recess during the molding process of the powder compact, the molding pressure is less likely to differ between the recessed portion and the non-recessed portion, thus making it easier to further homogenize the overall density of the powder compact.

[0060] [Details of the embodiments of this disclosure]

[0061] Hereinafter, specific examples of the connector, powder-pressed body, and method for manufacturing the powder-pressed body of this disclosure will be described based on the accompanying drawings. The same reference numerals in the drawings denote the same or equivalent parts. The sizes of the components shown in the drawings are for illustrative purposes only and do not necessarily represent actual dimensions. It should be noted that the present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims, as illustrated by the claims.

[0062] <Implementation Method 1>

[0063] Overall Structure

[0064] The connector 1 in this example includes a first component 11, a second component 12 configured to connect with the first component 11, and a self-tapping screw 13 connecting the first component 11 and the second component 12. The self-tapping screw 13 passes through the first component 11 to reach the second component 12 and is threadedly engaged with the second component 12. In this example, the second component 12 is a powder-molded body 2, and the first component 11 is a non-powder-molded body 3. One of the features of the connector 1 in this example is the structure of the powder-molded body 2. The structure of each part of the connector 1 in this example will be described in detail below.

[0065] Self-tapping screws

[0066] The self-tapping screw 13 has a shaft portion 13S and a head 13H. An external thread is formed on the outer periphery of the shaft portion 13S. The head 13H may also have a tool hole for inserting a screwdriver or similar tool. The type of self-tapping screw 13 is not particularly limited. For example, the self-tapping screw 13 can be type B-0 or type B-1. A type B-1 self-tapping screw 13 has a groove formed at its front end that serves as a cutting edge.

[0067] In connector 1 of this example, a washer 14, which is a different component from the self-tapping screw 13, is disposed between the head 13H and the first component 11. Alternatively, a self-tapping screw 13 that is integrated with the head 13H can also be used. In this case, the head 13H contacts the first component 11.

[0068] Powder-molded bodies

[0069] The pressed powder molded body 2 constituting the second component 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-Si-Al alloys, Fe-Si alloys, Fe-Al alloys, and Fe-Ni alloys. The soft magnetic particles may also have an insulating coating on their surface. By forming an insulating coating on the surface of the soft magnetic particles, the soft magnetic particles are electrically insulated from each other. When the pressed powder molded body 2 is used in the core of a rotating motor or the like, the eddy current loss of the core can be reduced by the insulating coating. The insulating coating is, for example, a phosphate coating or a silica coating.

[0070] The average particle size of the soft magnetic particles is, for example, 10µm or more and 400µm or less. If the average particle size of the soft magnetic particles is 10µm or more, the increase in hysteresis loss in the powder-pressed body 2 can be reduced when it is used in the core of a rotary motor or the like. If the average particle size of the soft magnetic particles is 400µm or less, the eddy current loss of the powder-pressed body 2 generated in the high-frequency region can be reduced when it is used in the core of a rotary motor or the like. The average particle size of the soft magnetic particles can be, for example, 10µm or more and 300µm or less, or 40µm or more and 260µm or less. Here, the average particle size refers to the particle size of the particles whose sum of mass from the smallest particle size to the largest particle size reaches 50% of the total mass in the particle size histogram, that is, the 50% particle size.

[0071] The relative density of the pressed powder molded body 2 is preferably 85% or higher. By increasing the density of the pressed powder molded body, it is less prone to cracking or breakage. The relative density of the pressed powder molded body 2 can be 90% or higher, 93% or higher, or 95% or higher. The relative density of the pressed powder molded body 2 is obtained by dividing its apparent density by its true density. The apparent density is calculated by determining the volume of the pressed powder molded body 2 using the Archimedes method and dividing its mass by the measured volume.

[0072] The powder-pressed molding body 2 includes 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 component 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. A shaft portion 13S of a self-tapping screw 13 is disposed in the first hole 25. The first hole 25 may also be a through hole that opens into the first surface 21 and the second surface 22. The second surface 22 is the surface opposite to the first surface 21.

[0073] The shaft portion 13S of the self-tapping screw 13 is threaded into the first hole 25. The first hole 25 is formed by screwing the self-tapping screw 13 into the base hole 24 pre-formed in the powder forming body 2. In this example, the base hole 24 is generally referred to as the prepared hole. The base hole 24 has an inner circumferential surface formed by a cylindrical surface. An internal thread portion 24f is formed in the base hole 24 by threading the self-tapping screw 13. The base hole 24 with the internal thread portion 24f is the first hole 25.

[0074] A gap is formed between the bottom surface of the first hole 25 and the front end of the shaft portion 13S. Therefore, the front end of the shaft portion 13S will not exert stress on the bottom surface of the first hole 25, and the powder-pressed molded body 2 is not prone to breakage.

[0075] The bottom of the first hole 25 can also be like... Figure 1 The shape shown is tapered at the front end. In this case, the front end of the shaft portion 13S of the self-tapping screw 13 is less likely to contact the bottom surface of the first hole 25, and even if the front end of the shaft portion 13S contacts the bottom surface of the first hole 25, the powder-molded body 2 is less likely to break. The included angle φ of the tapered shape at the bottom is, for example, 85° or more and 145° or less. The included angle φ is the angle between the left-hand inclined surface and the right-hand inclined surface at the bottom, separated by the axis, in the cross-section including the axis of the shaft portion 13S.

[0076] like Figure 2 As shown, the recess 23 is formed as an opening 25o surrounding the first hole 25. The opening area of ​​the recess 23 is larger than the opening area of ​​the first hole 25. That is, when viewed from above, the opening 25o of the first hole 25 is positioned inside the opening 23o of the recess 23.

[0077] The opening 23o of the recess 23 is, for example, accommodated in the washer 14 when viewed from above. Figure 1 The size of the inner side of the outer periphery of the self-tapping screw 13. In this case, the washer 14 will not fall into the recess 23. When the connector 1 does not use the washer 14, the opening 23o is, for example, the size of the inner side of the outer periphery of the head 13H of the self-tapping screw 13.

[0078] The inner circumferential surface 230 of the recess 23 is a compression-formed surface without cutting marks. It can be visually confirmed that the inner circumferential surface 230 is free of cutting marks. As will be described below, such a recess 23 can be formed by pressure forming. Since the opening 23o of the recess 23, formed without machining, does not contain defects caused by machining, furthermore, because the recess 23 is formed without machining, the production rate of the powder-formed body 2 is high.

[0079] 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 is based on 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 is likely to exceed 3.2 µm. That is, an arithmetic mean roughness Ra of 3.2 µm or less on the inner circumferential surface 230 is one of the indicators for the recess 23 formed by pressure forming.

[0080] In this example, the inner peripheral surface 230 of the recess 23 has 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 inclined in such a way that it gradually moves away from the axis 25s along the axis 25s of the first hole 25 towards the first surface 21.

[0081] As will be explained in the manufacturing method of connector 1 described below, bottom surface 231 is a structure designed to prevent the axis of self-tapping screw 13 from tilting when it is screwed in. As will be explained in the manufacturing method of powder-pressed body 2 described below, inclined surface 232 is designed to facilitate the powder-pressed body 2 from being easily removed from mold 9 (see reference 9) when the recess 23 is formed by forming it through the mold. Figure 3 The structure for pulling out the powder-formed body 2. The angle θ between the extended surface of the inclined surface 232 and the first surface 21 is less than 90°. The smaller the angle θ, the easier it is to pull out the powder-formed body 2 from the mold 9. The angle θ can be, for example, less than 80° or less than 70°. Regarding the lower limit of the angle θ, the angle θ can be, for example, greater than 30° or greater than 45°. In this example, the angle θ is 70°.

[0082] Unlike this example, the inner wall of the recess 23 can also be a wall perpendicular to the bottom surface 231. In this case, the angle θ between the extended surface of the wall and the first surface 21 is 90°.

[0083] As already described, when the self-tapping screw 13 is screwed into the base hole 24, the self-tapping screw 13 bites into the inner circumferential surface of the base hole 24, and a portion of the inner circumferential surface is shaved off. The shavings protrude as burrs 4 from the opening 25o of the first hole 25. In this example, since the recess 23 is formed to surround the opening 25o, the burrs 4 are disposed within the recess 23. Figure 1 As shown, the burr 4 disposed within the recess 23 is not sandwiched between the first component 11 and the second component 12. Therefore, no large gap is formed between the first component 11 and the second component 12, and the first component 11 and the second component 12 can be firmly connected. The firmly connected first component 11 and the second component 12 are not easily separated, and the connection can be maintained for a long time.

[0084] The depth D of the recess 23 for accommodating the burr 4 is, for example, 0.1 mm or more and 3.0 mm or less. The depth D of the recess 23 having the bottom surface 231 is the distance from the first surface 21 to the deepest point of the recess 23, and in this example, it 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, it is easy to accommodate the burr 4 within the recess 23. If the depth D of the recess 23 is 3.0 mm or less, the solid portion of the powder compact 2 will not be excessively reduced. The mold 9 used to form the powder compact 2 (see...) Figure 3 The strength of the portion corresponding to the recess 23 is not easily reduced. The depth D of the recess 23 can, for example, be 0.3 mm or more and 1.0 mm or less.

[0085] 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 self-tapping screw 13 into the base hole 24 when manufacturing the connector 1. If the length L1 is 3.0 mm or less, the recess 23 will not become too large, the first component 11 and the second component 12 will have sufficient contact area, and the connection between the first component 11 and the second component 12 will be easy to stabilize. Here, the smaller the included angle θ, the longer the length L1. Therefore, the upper limit of the length L1 can also be regarded as defining the lower limit of the included angle θ. If the included angle θ is above the lower limit value, it is not only easy to pull out the powder-pressed body 2 from the mold 9, but also the length L1 will not become too large even if the depth D of the recess 23 is increased.

[0086] Non-pressed Powder Molded Body

[0087] The non-pressed molding body 3 constituting the first component 11 is not limited to the pressed molding body 2. For example, the non-pressed molding body 3 can be metal or resin. The non-pressed molding body 3 has a through hole 35 through which the shaft portion 13S of the self-tapping screw 13 is inserted. The inner diameter of the through hole 35 is larger than the inner diameter of the shaft portion 13S. That is, the through hole 35 is a through hole through which only the self-tapping screw 13 passes. In this example, the through hole 35 does not have an internal thread on its inner circumferential surface, but has an inner circumferential surface composed of a cylindrical surface. Unlike this example, the through hole 35 can also be a threaded hole with an internal thread on its inner circumferential surface. In this case, a portion of the shaft portion 13S is threadedly engaged with the through hole 35.

[0088] Manufacturing Method of Powder-Pressed Molded Articles

[0089] By using Figure 3 The mold 9 shown is used to mold and form the powder-pressed body 2 constituting the second component 12. The mold 9 includes a die 91, a lower punch 92, and an upper punch 93. When manufacturing the powder-pressed body 2 using this mold 9, the lower punch 92 is first inserted 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 inserted into the die 91 from above, and the upper punch 93 is moved downwards, compressing the soft magnetic powder between the lower punch 92 and the upper punch 93. The compression direction is the moving direction of the upper punch 93, i.e., the downward direction. The powder-pressed body 2 is manufactured by this compression. Here, a protrusion 93p for forming the recess 23 of the powder-pressed body 2 is formed on the lower surface of the upper punch 93. In this example, a recess is formed on the end face of the protrusion 93p.

[0090] Figure 4 This is a partial enlarged view of the area near the recess 23 of the powder forming body 2. A recess 23 with the shape of a protrusion 93p of an upper punch 93 transferred onto the first surface 21 of the powder forming body 2 is formed. In this example, the recess 23 has an inclined surface 232, so when the upper punch 93 is moved upward to remove the powder forming body 2 from the mold 9, the upper punch 93 can easily separate from the powder forming body 2.

[0091] In this example, a thickened portion 23b protruding from the bottom surface 231 of the recess 23 in the powder compaction body 2 is formed at the position of the recess 23 formed on the end face of the protrusion 93p. By forming the thickened portion 23b, during mold forming, the forming pressure along the compression direction is less likely to differ between the portion having the recess 23 and the portion other than the recess 23. Therefore, the overall density of the powder compaction body 2 is easily homogenized. The protrusion height of the thickened portion 23b protruding from the bottom surface 231 is, for example, 50% or more and 100% or less of the depth D of the recess 23. The aforementioned protrusion height can be 60% or more, 70% or more, or 80% or more of the depth D.

[0092] Unlike this example, the protrusion 93p used to form the recess 23 of the powder forming body 2 can also be formed on the lower punch 92.

[0093] Next, a basic hole 24 extending from the bottom surface 231 of the recess 23 is formed by drilling. Figure 4 In the diagram, the area where the basic hole 24 is formed is indicated by a double-dotted line. The inner diameter of the basic hole 24 is smaller than the outer diameter of the self-tapping screw 13. The area where the basic hole 24 is formed is smaller than the bottom surface 231. Therefore, the bottom surface 231 remains in a ring-shaped manner around the opening of the basic hole 24. When forming the basic hole 24, the entire thickened portion 23b is removed. Unlike this example, the basic hole 24 can also be formed by die forming, but in this case, the density near the basic hole 24 in the powder-pressed body 2 is more likely to decrease compared to other parts. In the case where the basic hole 24 is formed after die forming as in this example, the density near the basic hole 24 is not significantly reduced compared to other parts.

[0094] Here, when the base hole 24 is formed by drilling, a burr (not shown) protrudes from the opening 24o of the base hole 24. Since the burr is located in the recess 23, it does not need to be removed. The burr can also be removed, but in this case, care should be taken to avoid creating defects at the edge of the opening 24o of the base hole 24.

[0095] The powder compact 2 can also be heat-treated before or after drilling. Heat treatment removes strain from the powder compact 2, thereby enabling the manufacture of a powder compact 2 with low loss. Furthermore, heat treatment facilitates the removal of binders or lubricants contained in the powder compact 2. The heat treatment temperature is, for example, 400°C or higher and 900°C or lower.

[0096] Manufacturing Method of Connectors

[0097] The pressed powder molded body 2, formed by molding, and the non-pressed powder molded body 3, prepared separately from the pressed powder molded body 2, are as follows: Figure 1 The self-tapping screw 13 is inserted into the through hole 35 of the non-pressed powder forming body 3 and screwed into the base hole 24 of the pressed powder forming body 2. At this time, since a bottom surface 231 is formed in the recess 23, the front end of the shaft portion 13S of the self-tapping screw 13 is not easily tilted relative to the axis of the base hole 24, and the shaft portion 13S can be easily guided straight to the base hole 24.

[0098] During the process of screwing the self-tapping screw 13 into the base hole 24, a burr 4 is generated. This burr 4 is disposed in the recess 23 and will not be trapped between the first component 11, which is made of non-pressed powder forming body 3, and the second component 12, which is made of pressed powder forming body 2. In this way, a connecting body 1 that firmly connects the first component 11 and the second component 12 is manufactured by using the pressed powder forming body 2 with the recess 23.

[0099] <Implementation Method 2>

[0100] based on Figure 5 The connector 1 according to Embodiment 2 will be described. In the connector 1 of this example, the first component 11 is a powder-pressed molding body 2, and the second component 12 is a non-powder-pressed molding body 3.

[0101] In this example, the first surface 21 of the powder-forming body 2 faces the head 13H of the self-tapping screw 13. The recess 23 formed on the first surface 21 also faces the head 13H. The first hole 25 is a through hole extending from the first surface 21 to the second surface 22. An internal thread 24f extending the entire length of the first hole 25 is formed on the inner circumferential surface of the first hole 25. This internal thread 24f is formed by the self-tapping screw 13. In this connecting body 1, burrs 4 generated by the self-tapping screw 13 are also disposed in the recess 23. The burrs 4 are not trapped between the first component 11, which is made of the powder-forming body 2, and the head 13H firmly applies equal pressure to the first surface 21. For this reason, the first component 11 and the second component 12 are firmly connected, and the connection is not easy to loosen.

[0102] A threaded hole 36 is formed in the second component 12, which is composed of a non-powder-formed body 3. A self-tapping screw 13 is threaded into the threaded hole 36. The threaded hole 36 may have an internal thread portion pre-formed with a tap, or it may have an internal thread portion formed by the self-tapping screw 13.

[0103] <Implementation Method 3>

[0104] based on Figure 6 The connector 1 according to Embodiment 3 will be described. In the connector 1 of this example, the first component 11 and the second component 12 are both powder-pressed molding bodies 2.

[0105] The first surface 21 and recess 23 of the powder-forming body 2 constituting the first component 11 face the head 13H of the self-tapping screw 13. The first hole 25 of the first component 11 is a through hole, and an internal thread 24f is formed along the entire length of its inner circumferential surface. The first surface 21 and recess 23 of the powder-forming body 2 constituting the second component 12 face the second surface 22 of the first component 11. The first hole 25 of the second component 12 is a blind hole, and an internal thread 24f is formed on a portion of its inner circumferential surface. The internal thread 24f in the first hole 25 of the first component 11 and the second component 12 is formed by the self-tapping screw 13. In the structure of this example, the burrs 4 generated by the self-tapping screw 13 in each powder-forming body 2 are disposed in the recess 23 of the powder-forming body 2 that generates the burrs 4. For this reason, the first component 11 and the second component 12 are firmly connected, and the connection is not easy to loosen.

[0106] <Implementation Method 4>

[0107] based on Figure 7 The connector 1 according to Embodiment 4 will be described. In the connector 1 of this example, the first component 11 is a powder-formed body 2, and the second component 12 is a non-powder-formed body 3. The screw 15 connecting the first component 11 and the second component 12 is not a self-tapping screw. The threaded hole 36 of the second component 12 has an internal thread portion obtained by machining the bottom hole with a tap. The first component 11 and the second component 12 are connected by threading the shaft portion 15S of the screw 15 into the threaded hole 36.

[0108] The first component 11 facing the head 15H of the screw 15 is a powder-forming body 2. The first hole 25 of the powder-forming body 2 is a through hole with an inner diameter larger than the outer diameter of the shaft portion 15S of the screw 15. No internal thread is formed on the inner circumferential surface of the first hole 25. This first hole 25 is itself a base hole 24 formed by drilling during the manufacture of the powder-forming body 2. The burr 4 disposed in the recess 23 is generated during drilling.

[0109] In this example, the connector 1 is manufactured by connecting the powder-pressed body 2 and the non-powder-pressed body 3 without removing the burrs 4 generated when forming the basic holes 24 in the powder-pressed body 2. Corresponding to the fact that the burrs 4 do not need to be removed, the productivity of the connector 1 is high.

[0110] <Implementation Method 5>

[0111] As a reference Figure 5 A variation of implementation 2, based on Figure 8 The connecting body 1 according to Embodiment 5, in which the powder-pressed molding body 2 has a storage portion 29, will be described. In the connecting body 1 of this example, the first component 11 is the powder-pressed molding body 2, and the second component 12 is the non-powder-pressed molding body 3.

[0112] The powder-molded body 2 constituting the first component 11 has a receiving portion 29 that receives the entire head 13H of the self-tapping screw 13. In this case, the bottom surface of the receiving portion 29 becomes the first surface 21. In the connector 1 of this example, the burr 4 generated by the self-tapping screw 13 is also provided in the recess 23.

[0113] <Implementation Method 6>

[0114] In implementation method 6, based on Figure 9 An example of applying the structure of the connector 1 shown in Embodiment 1 to the rotary motor 5 will be described. The rotary motor 5 can be a generator or an electric motor.

[0115] The rotary motor 5 in this example includes a rotor 6, a stator 7, and a housing 8. The rotary motor 5 in this example is an axially spaced rotary motor 5 in which the rotor 6 and the stator 7 are arranged along the rotation axis of the rotor 6.

[0116] Rotor

[0117] The rotor 6 comprises a plurality of flat magnets 61 and an annular retaining plate 60 supporting 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. Furthermore, the magnets 61 are magnetized in the direction along the shaft 50. The magnetization directions of adjacent magnets 61 in the direction of rotation of the shaft 50 are opposite to each other.

[0118] "stator"

[0119] The stator 7 includes an iron core 70 and a plurality of coils 75. The iron core 70 includes a circular magnetic yoke 71 and a plurality of teeth 72. The teeth 72 may also have flanges 72f as shown in embodiment 7, which will be described below. Figure 10 Multiple teeth 72 protrude from one side of the magnetic yoke 71. A coil 75 is arranged on each tooth 72. The rotary motor 5 in this example has 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 iron core 70 in this example is formed from a powder-pressed molding body 2.

[0120] "case"

[0121] The housing 8 houses the rotor 6 and the stator 7. The housing 8 is, for example, a non-magnetic material. The non-magnetic material is, for example, an aluminum alloy. A shaft 50 connected to the rotor 6 passes through the housing 8. A bearing 51 is disposed between the outer circumferential surface of the shaft 50 and the housing 8.

[0122] In this example of the rotary motor 5, the iron core 70 formed by the powder-pressed molding body 2 and the housing 8 formed by the non-powder-pressed molding body 3 are connected by self-tapping screws 13. Burrs 4 are generated due to the self-tapping screws 13. Figure 1 It will not be trapped between the iron core 70 and the housing 8. Therefore, the iron core 70 is firmly fixed to the housing 8, and the rotation of the rotor 6 is stable.

[0123] The rotary motor 5 in this example is a single-rotor, double-stator type rotary motor. The rotary motor 5 using the structure of the connecting body 1 can also be other types of rotary motors, such as a double-rotor, single-stator type rotary motor.

[0124] <Implementation Method 7>

[0125] In implementation method 7, based on Figure 10 A rotary motor 5 having a connecting body 1 different from that in embodiment 6 will be described. Figure 10 The diagram shows only the left half of the rotary motor 5, and the housing is omitted.

[0126] In this example, the teeth 72 of the core 70 have flanges 72f. The flanges 72f extend laterally from the ends of the teeth 72 on the side of the teeth 72. The magnetic characteristics of the rotary motor 5 are improved by the flanges 72f.

[0127] In this example, the yoke 71 and teeth 72 of the iron core 70 are manufactured independently. The yoke 71 and teeth 72 are connected by self-tapping screws 13 to form the connecting body 1 of embodiment 7. In this case, the yoke 71 is the first component 11 and the teeth 72 is the second component 12.

[0128] In this example, the yoke 71 is a non-pressed material 3, and the tooth 72 is a pressed material 2. The non-pressed material 3 is, for example, an SS400 plate, a SUS plate, or a laminated steel plate. Unlike this example, both the yoke 71 and the tooth 72 can be pressed materials 2, or the yoke 71 can be a pressed material 2, while the tooth 72 is a non-pressed material 3.

[0129] <Implementation Method 8>

[0130] In implementation method 8, based on Figure 11 A rotary motor 5 having a connecting body 1 different from those in embodiments 6 and 7 will be described. Figure 11 The diagram shows only the left half of the rotary motor 5, and the housing is omitted.

[0131] In this example, the yoke 71 of the iron core 70 is integrated with the tooth 72, and the iron core 70 also includes a flange member 73 disposed on the end face of the tooth 72. The flange member 73 is a plate-shaped component, as described in embodiment 7. Figure 10 The function of the end of the tooth 72 and the flange 72f.

[0132] In this example, the teeth 72 of the core 70 and the flange member 73 are manufactured independently. The teeth 72 and the flange member 73 are connected by self-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.

[0133] In embodiment 8, the magnetic yoke 71 and the tooth 72 can also be independent components. In this case, the magnetic yoke 71 and the tooth 72 can be connected by self-tapping screws 13, as in embodiment 7.

[0134] <Postscript>

[0135] The structure of the connector disclosed herein can be applied to the connection of injection-molded bodies. Specifically, the connector includes: a first component; a second component configured to engage with the first component; and a screw passing through the first component to the second component, connecting the first component and the second component, wherein at least one of the first component and the second component is an injection-molded body. The injection-molded body includes: a first surface facing the head of the first component or the screw that engages with the injection-molded body; a recess formed on the first surface; and a first hole extending from the recess for the shaft portion of the screw to be 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 has no cutting marks.

[0136] Injection-molded articles are, for example, composite materials or resin molded articles comprising resin and powder. In composite materials, the powder is dispersed in the resin. The powder is, for example, a soft magnetic powder. Through the noted structure, when connecting the first component and the second component, burrs protruding from the opening of the first hole can be disposed within the recess, enabling a secure connection between the first component and the second component.

[0137] Explanation of reference numerals in the attached figures

[0138] 1 Connector; 2 Powder-formed body; 3 Non-powder-formed body; 4 Burr; 5 Rotary motor; 6 Rotor; 7 Stator; 8 Housing; 9 Mold; 11 First component; 12 Second component; 13 Self-tapping screw; 13H Head; 13S Shaft; 14 Washer; 15 Screw; 15H Head; 15S Shaft; 21 First surface; 22 Second surface; 23 Recess; 23b Thickened part; 23o Opening; 24 Base hole; 24f Internal threaded part; 24o Opening; 25 First hole; 25o Opening; 25s Axis; 29 Reception part; 35 Through hole; 36 Threaded hole; 50 Shaft; 51 Bearing; 60 Retaining plate; 61 Magnet; 70 Iron core; 71 Magnetic yoke; 72 Tooth; 72f Flange; 73 Flange component; 75 Coil; 91 Die; 92 Lower punch; 93 Upper punch; 93p Protrusion; 230 Inner circumferential surface; 231 Bottom surface; 232 Inclined surface; D Depth; L1 Length; θ, φ Angles.

Claims

1. A connector, comprising: First component; The second component is configured to connect with the first component; and A screw penetrates the first component and reaches the second component, connecting the first component and the second component. At least one of the first component and the second component is a powder-pressed body. The powder-pressed body comprises: The first side faces the head of the first component or the screw that is in contact with the powder forming body; A recess is formed on the first surface; and A first hole extends from the recess for the shaft portion of the screw to be positioned. The opening area of ​​the recess is larger than the opening area of ​​the first hole. The inner circumferential surface of the recess has no cutting marks.

2. The connector according to claim 1, wherein, The second component is the powder-pressed molding body. The surface of the second component that faces the first component is the first surface.

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

4. The connector according to claim 3, wherein, The relative density of the pressed powder molded body is above 85%.

5. The connector according to claim 4, wherein, The pressed powder-formed body contains soft magnetic powder. The soft magnetic powder is an aggregate of soft magnetic particles with an insulating coating on their surface. The soft magnetic particles are selected from at least one group consisting of pure iron, Fe-Si-Al alloys, Fe-Si alloys, Fe-Al alloys, and Fe-Ni alloys.

6. The connector according to claim 1 or 2, wherein, The inner peripheral surface of the recess has an inclined surface connected to the first surface. The angle between the extended surface obtained by extending the inclined surface outward beyond the first surface and the first surface is less than 90°.

7. The connector according to claim 1 or 2, wherein, The depth of the recess is greater than 0.1 mm and less than 3.0 mm.

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

9. The connector according to claim 1 or 2, wherein, The second component is the stator core of the rotating electric motor. The first component is a housing that houses the stator. The iron core is formed by the powder-pressed body.

10. The connector according to claim 1 or 2, wherein, The second component is the teeth on the iron core of the stator of the rotary electric motor. The first component is the magnetic yoke of the iron core. The teeth are formed by the powder-pressed molding body.

11. The connector according to claim 1 or 2, wherein, The second component is the teeth on the iron core of the stator of the rotary electric motor. The first component is a flange component disposed on the end face of the tooth. The teeth are formed by the powder-pressed molding body.

12. A powder-pressed body connected to other components by screws, the powder-pressed body comprising: The first side is configured to face the other components or the head of the screw when the powder-pressed body is connected to the other components; A recess is formed on the first surface; and A base hole extends from the recess and is configured to allow the shaft portion of the screw to be positioned when the powder-pressed body is connected to the other components. The opening area of ​​the recess is larger than the opening area of ​​the base hole. The inner circumferential surface of the recess has no cutting marks.

13. A method for manufacturing a powder-pressed molded body, wherein the recess of the powder-pressed molded body is formed by forming a mold for manufacturing the powder-pressed molded body according to claim 12.

14. The method for manufacturing a powder-pressed molded article according to claim 13, wherein, The base hole is formed by drilling after the mold is formed.

15. The method for manufacturing a powder-pressed molded article according to claim 14, wherein, The thickened portion protruding from the bottom surface of the recess is formed by the mold. The entire thickened portion is removed through the drill hole.

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