Manufacturing method of rotor

The manufacturing method of a rotor includes: a step of preparing a plate that is composed of an austenitic material and that has a projected portion and a part with a width in a rotational axis direction smaller than a width of the projected portion in the rotational axis direction; and a step of forming a welded portion across the projected portion of the plate and a rotation transmitting member by emitting an energy beam on at least a part of the projected portion to melt at least a part of the projected portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2019/000708, filed Jan. 11, 2019, claiming priority from Japanese Patent Application No. 2018-002675, filed Jan. 11, 2018, the contents of which are incorporated in their entirety by reference.

TECHNICAL FIELD

Aspect of the disclosure related to a manufacturing method of a rotor.

BACKGROUND ART

Conventionally, a manufacturing method of a rotor including a plate and a rotation transmitting member is known. Such a manufacturing method of a rotor is disclosed in Japanese Unexamined Patent Application Publication No. 2015-119557 (JP 2015-119557 A), for example.

JP 2015-119557 A discloses a manufacturing method of a rotor including a rotor core, end plates (plate), and a shaft body (rotation transmitting member). In the manufacturing method of the rotor, an inner peripheral surface of the rotor core and an outer peripheral surface of the shaft body are welded. Then, plate inner peripheral surfaces of the end plates and the outer peripheral surface of the shaft body are welded. In this way, the rotor in which the rotor core, the shaft body, and the end plates are fixed to each other is manufactured.

RELATED ART DOCUMENTS

Patent Documents

SUMMARY OF THE DISCLOSURE

Problem to be Solved by the Various Aspects of the Disclosure

Here, although not described in JP 2015-119557 A, it is preferable that the rotation transmitting member (shaft body) be configured of a material having a relatively hard structure, in view of a function of transmitting rotational motion between the rotor core and a shaft or a gear portion or the like. Specifically, the rotation transmitting member is composed of a martensitic material. Although the structure of martensite is harder than the structure of austenite or the structure of ferrite, martensitic material is disadvantageous in that low-temperature cracking, which is cracking that occurs after welding to another member (plate), is likely to occur. When low-temperature cracking occurs, it is difficult to ensure joining strength of the welded part. Thus, there has conventionally been a demand for a manufacturing method of a rotor where joining strength can be ensured when a plate is welded and fixed to a rotation transmitting member composed of a martensitic material.

The various aspects of the present disclosure have been made to solve the problem described above, and it is one aspect of the present disclosure to provide a manufacturing method of a rotor in which joining strength can be ensured even when a plate is welded and fixed to a rotation transmitting member composed of a martensitic material.

Means for Solving the Problem

In order to achieve the above aspect, a manufacturing method of a rotor including a rotor core, a plate that is disposed on at least one side of the rotor core in a rotational axis direction, and a rotation transmitting member that is composed of a martensitic material and that is welded and fixed to the plate. The manufacturing method includes: a step of preparing the plate that has a projected portion that is provided adjacent to the rotation transmitting member in a radial direction and that is projected, from an end face in the rotational axis direction, in a direction away from the rotor core out of the rotational axis direction, and a part that is adjacent to the projected portion in the radial direction and that has a width in the rotational axis direction smaller than a width of the projected portion in the rotational axis direction, the plate being formed of an austenitic material; a step of disposing the rotation transmitting member radially inward of the plate, after the step of preparing the plate; and a step of forming a welded portion across the projected portion of the plate and the rotation transmitting member by emitting an energy beam on at least a part of the projected portion to melt at least a part of the projected portion, after the step of disposing the rotation transmitting member.

In the rotor manufacturing method according to one aspect of the present disclosure, as described above, at least a portion of the projected portion is melted to form the welded portion across the projected portion of the plate and the rotation transmitting member. In this way, it is possible to decrease the heat capacity of the projected portion (a part of the plate to be melted), compared to when a part of the plate to be melted is formed as a surface that is not projected. As a result, since the melted amount of the plate composed of the austenitic material can be increased compared to when the projected portion is not provided, it is possible to increase the melting ratio of the austenitic material in the welded portion. As a result, since low-temperature cracking can be made less likely to occur in the welded portion, it is possible to ensure joining strength even when the plate is welded and fixed to the rotation transmitting member composed of martensitic material. Here, in order to increase the melting ratio of the austenitic material in the welded portion, it is conceivable that welding is performed while a welding wire composed of the austenitic material is supplied to the part being melted. However, in this case, there is a problem that the rotor manufacturing equipment increases in size, since it is necessary that a rotor manufacturing equipment is provided with a wire supply device that supplies the welding wire, separately from the welding device. In contrast, in the manufacturing method of the rotor according to the first aspect of the present disclosure, it is possible to melt the projected portion that is composed of austenitic material and that is provided beforehand on the plate. It is thus possible to increase the melting ratio of the austenitic material in the welded portion without the rotor manufacturing equipment being provided with the wire supply device. As a result, it is possible to ensure joining strength of the rotation transmitting member and the plate while preventing the rotor manufacturing equipment (welding equipment) from increasing in size.

Effects of the Disclosure

According to the present disclosure, as described above, joining strength can be ensured even when the plate is welded and fixed to the rotation transmitting member composed of a martensitic material.

DETAILED DESCRIPTION

The structure of a rotor100according to the first embodiment will be described with reference toFIGS. 1 to 8.

In the present specification, a “rotational axis direction” means a direction along a rotational axis C of the rotor100(Z direction, seeFIG. 1). A “circumferential direction” means a circumferential direction of the rotor100(arrow A1direction or arrow A2direction, seeFIG. 2). Further, “radially inward” means a direction toward the center of the rotor100(arrow R1direction). In addition, “radially outward” means a direction toward the outside of the rotor100(arrow R2direction).

As illustrated inFIG. 1, the rotor100forms a part of a rotating electrical machine101. For example, the rotating electrical machine101is configured as an inner rotor type rotating electrical machine. That is, in the rotating electrical machine101, the stator10is disposed radially outward of the rotor100. The stator10includes a stator core11and a winding12wound around the stator core11.

The rotor100includes a rotor core20, end plates30, and a hub member40. The end plates30and the hub member40are joined to each other by first welded portions50. The rotor core20and the hub member40are joined to each other by second welded portions60. The end plates30are an example of a “plate” in the claims. The hub member40is an example of a “rotation transmitting member” in the claims. The first welded portions50are an example of a “welded portion” in the claims. The second welded portions60are an example of a “core welded portion” in the claims.

As illustrated inFIG. 1, the rotor core20includes a plurality of electromagnetic steel plates21. The rotor core20is formed by stacking the electromagnetic steel plates21in the rotational axis direction (Z direction) in which the rotational axis C extends. The electromagnetic steel plates21are composed of, for example, a silicon steel sheet that is a magnetic material. Each of the electromagnetic steel plates21is formed in an annular shape with the rotational axis C as the center, and the electromagnetic steel plates21are configured to have a cylindrical shape and extends in the rotational axis direction when stacked.

A through hole22is provided radially inward of the rotor core20. The hub member40is disposed in the through whole22of the rotor core20. A core inner peripheral surface22athat configures the through whole22of the rotor core20and an outer peripheral surface41of the hub member40are joined by the second welded portions60.

The rotor core20is provided with a plurality of insertion holes24in which respective permanent magnets23are inserted. As illustrated inFIG. 2, the insertion holes24are provided at regular angular intervals along the circumferential direction of the annular rotor core20. The insertion holes24are formed, for example, so as to extend from a core end face25aof the rotor core20on the arrow Z1direction side to a core end face25bof the rotor core20on the arrow Z2direction side.

As illustrated inFIG. 3, the rotor core20is provided with the following: recessed portions26that are each recessed radially outward from the core inner peripheral surface22aof the through hole22as viewed in the rotational axis direction; and a protruded portion27that is provided between two adjacent recessed portions26and that protrudes toward the rotational axis C. The recessed portions26are each formed, for example, as an oil passage that allows automatic transmission fluid (ATF) to pass through (for example, see arrow B inFIG. 3). The automatic transmission oil has a function of cooling the rotor100and the stator10.

The rotor core20is provided with core forming welded portions28that are formed by melting the protruded portions27. The magnetic steel plates21are joined to each other by the core forming welded portions28. Specifically, the core forming welded portions28are each provided near the top of the protruded portion27, so as to extend from the core end face25ato the core end face25b.

(Configuration of End Plate)

The end plates30are composed of a non-magnetic material. In the present embodiment, the end plates30are composed of stainless steel of austenitic material. The end plates30are preferably composed of, for example, SUS304 or SUS309 prescribed by the Japanese Industrial Standards (JIS).

As illustrated inFIG. 1, the end plates30are disposed on one side (core end face25a) and the other side (core end face25b) of the rotor core20in the rotational axis direction. The two end plates30are disposed so as to sandwich the rotor core20from both sides in the rotational axis direction. As illustrated inFIG. 4, the end plate30is formed in an annular shape as viewed in the rotational axis direction. An inner peripheral surface31of the end plate30is disposed nearly flush with the core inner peripheral surface22ain the rotational axis direction.

As illustrated inFIG. 5, each of the end plates30is disposed such that the inner peripheral surface31of the end plate30faces the outer peripheral surface41of the hub member40in the radial direction. Plate-side joining end faces31aof the inner peripheral surface31of the end plate30and hub-side joining end faces41aof the outer peripheral surface41of the hub member40are welded at the first welded portion50and thus, the end plate30and the hub member40are fixed to each other.

A thickness t2of the end plate30is larger than a thickness t1of the electromagnetic steel sheet21in the rotational axis direction. As illustrated inFIG. 6, the thickness t2of the end plate30means the length from an end face30ato an end face30b, and is described so as to mean the thickness in the rotational axis direction excluding the thickness t4of a bottom plate portion32c.

As illustrated inFIGS. 6 and 7, in the present embodiment, the end plate30includes projected portions70that are each provided adjacent to and radially outward of the plate-side joining end face31aof the inner peripheral surface31; that are each projected from a bottom face32aof a depressed portion32, which is an end face of the end plate30in the rotational axis direction, toward a direction (arrow Z1direction) away from the rotor core20out of the rotational axis direction; and that each have a part of the first welded portion50and a non-melted portion71, which is a part that is not melted. The projected portion70is formed between the depressed portion32and the plate-side joining end face31ain the radial direction. The “part that is not melted (non-melted portion71)” is not limited to a part in which there is no structural change when welded, and means a broad concept including heat-affected zones in which there is structural change due to welding heat. The plate-side joining end faces31aare an example of an “inner wall surface” in the claims.

Since the configuration of the end plate30disposed on the core end face25a(arrow Z1direction side) is similar to the end plate30disposed on the core end face25b(arrow Z2direction side) as illustrated inFIG. 5, in the following description, only the end plate30disposed on the core end face25awill be described and the description of the end plate30disposed on the core end face25bwill be omitted.

As illustrated inFIG. 6, the projected portion70includes a top surface72that is a surface in the projecting direction (arrow Z1direction side), the plate-side joining end face31a, and an inclined surface73. Here, in the present embodiment, the top surface72of the projected portion70is formed so as to be inclined radially inward (toward the hub member40) (in the arrow E1direction) as the top surface72extends toward a direction away from the rotor core20out of the rotational axis direction. That is, a projected height h1(a thickness t3of the end plate30) of the projected portion70in the rotational axis direction is larger on the hub member40side and smaller on the opposite side (depressed portion32side) of the projected portion70from the hub member40. The projected height h1of the projected portion70is a length from the bottom face32ato the top surface72. InFIG. 6, the projected height h1indicates a projected height of a part in which the projected height is the maximum (for example, the position near the plate-side joining end face31a). The thickness t3means a length from the end face30aof the end plate30on the rotor core20side to the top surface72.

Here, a top surface172(dotted line), which is the top surface72before the first welded portion50is formed, is formed as a flat surface orthogonal to the rotational axis direction. The top surface72is formed by deforming (providing excess weld material on) the top surface172when the first welded portion50is formed so that the top surface172rises to the arrow Z1direction side. That is, a weld bead (weld mark) is formed on the top surface72.

The plate-side joining end face31aforms a part of the inner peripheral surface31of the end plate30along the rotational axis direction before the first welded portion50is formed. Within the first welded portion50, a part of the plate-side joining end face31ais included (dotted line part), when the rotor100is completed. A length L1of the plate-side joining end face31ain the rotational axis direction is equal to the thickness t3. Although the expression “end face” is used for the description, the plate-side joining end face31aalso means a state (dotted line part) where a part of the plate-side joining end face31ais included within the first welded portion50, as described above.

Here, in the present embodiment, the inclined surface73is formed to be continuous with the top surface72of the projected portion70and the bottom face32aof the depressed portion32, and is configured to be inclined radially outward (in the direction away from the hub member40) with respect to the rotational axis direction, from the top surface72to the bottom face32a. That is, a width W1of the top surface72in the radial direction is smaller than a width W2of a root portion74of the projected portion70in the radial direction.

Here, it is preferable that an inclination angle θ1of the inclined surface73be 30 degrees or more and 60 degrees or less (for example, 40 degrees or more and 50 degrees or less) with respect to a plane orthogonal to the rotational axis direction. If the inclination angle of the inclined surface73is smaller than 30 degrees, the projected height h1(described below) of the projected portion70is relatively small, or the width W2of the root portion74of the projected portion70is relatively large, and the heat capacity of the projected portion70is increased. Thus, when the first welded portion50is formed, the input heat is easily transmitted to a radially outward part of the end plate30. The melting ratio of the end plate30in the first welded portion50is thus decreased. If the inclination angle of the inclined surface73is larger than 60 degrees, when an emission position P1of an energy beam described below is shifted from the top surface72to the inclined surface73, the energy beam is scattered and reflection of the energy beam is increased and thus, the input heat amount to the projected portion70(first welded portion50) is decreased. In contrast, if the inclination angle of the inclined surface73is set to be 30 degrees or more and 60 degrees or less, it is possible to prevent the melting ratio of the end plate30in the first welded portion50from decreasing and it is possible to prevent the input heat amount from decreasing.

As illustrated inFIG. 8, the projected portion70is provided radially inward of the insertion hole24in which the permanent magnet23is disposed as viewed in the rotational axis direction. A part of the projected portion70is disposed so as to overlap with at least a part of the recessed portion26and at least a part of the protruded portion27of the rotor core20, as viewed in the rotational axis direction.

<Structures other than Projection Portion>

As illustrated inFIG. 6, the depressed portion32includes the inclined surface73, the bottom face32a, and a radially outward inclined surface32b. The bottom face32ais configured as, for example, a flat surface orthogonal to the rotational axis direction. The radially outward inclined surface32bis formed so as to connect the bottom face32aand the end face30aof the end plate30on the arrow Z1direction side. The radially outward inclined surface32bis formed as an arcuate or linear inclined surface that is inclined radially outward toward the arrow Z1direction. A depression depth d1of the depressed portion32corresponds to the magnitude of the displacement of the position in the rotational axis direction between the bottom face32aand the end face30a.

As illustrated inFIG. 8, in the present embodiment, the end plate30has clearance portions33that are each depressed radially outward from the plate-side joining end face31aat a position adjacent to the projected portion70in the circumferential direction, as viewed in the rotational axis direction (arrow Z2direction). Specifically, the clearance portions33are each configured as a recessed portion that is depressed radially outward, and a part of the core end face25a(part of the core end face25b) and each second welded portion60are exposed via the clearance portion33, as viewed from the outside in the rotational axis direction. The clearance portions33are an example of a “core welding clearance portion” in the claims.

Each of the clearance portions33is disposed so as to be sandwiched from both sides by the projected portions70in the circumferential direction. Thus, in the projected portion70, the heat capacity is further reduced when the first welded portion50is formed.

As illustrated inFIG. 5, the end plates30are each provided with a bent portion34that is provided radially outward of the depressed portion32and that is bent and projected toward the outside in the rotational axis direction (direction away from the rotor core20).

In the present embodiment, the hub member40is composed of a martensitic material. Specifically, the hub member40is composed of carbon steel of a martensitic material (for example, S25C or S35C prescribed by JIS). It is preferable that S25C be adopted as the hub member40. Here, S25C has a relatively small carbon component and is relatively easy to weld.

As illustrated inFIG. 1, the hub member40is connected to a shaft member40a, and is configured to transmit rotational motion between the rotor core20and the shaft member40a, and between the end plates30and the shaft member40a.

As illustrated inFIG. 8, the hub member40is configured to have a cylindrical shape, and the outer peripheral surface41is provided with the first welded portions50and the second welded portions60. The outer peripheral surface41is provided with the hub-side joining end faces41athat each face the plate-side joining end face31ain the radial directions. A part of each hub-side joining end face41ais integrated with a part of the plate-side joining end face31ain a state where the first welded portion50is formed (seeFIG. 6). That is, there is no boundary between the hub-side joining end face41aand the plate-side joining end face31a. The outer peripheral surface41is an example of an “outer diameter surface of the rotation transmitting member” in the claims. The hub-side joining end faces41aare an example of a “facing surface that faces the inner wall surface” in the claims.

As illustrated inFIG. 6, in the present embodiment, the hub member40is provided with a heat releasing portion41bthat configures a part of the outer peripheral surface41of the hub member40and that is formed so as to be continuously in flush with the hub-side joining end faces41ain a direction away from the rotor core20(toward the arrow Z1direction) out of the rotational axis direction.

(Configuration of First Welded Portion: Configuration of Welded Portion Between End Plate and Hub Member)

As illustrated inFIG. 5, the first welded portions50are provided on both sides of the rotor100in the Z direction. For example, as illustrated inFIG. 2, the plurality of first welded portions50are provided at regular angular intervals in the circumferential direction. As illustrated inFIG. 8, the first welded portion50is provided radially inward of the insertion hole24in which the permanent magnet23is disposed, as viewed in the rotational axis direction. In addition, a part of the first welded portion50is disposed so as to overlap with at least a part of the recessed portion26and at least a part of the protruded portion27of the rotor core20, as viewed in the rotational axis direction.

As illustrated inFIG. 5, the first welded portion50is formed across from the projected portion70of the end plate30to the hub member40via the plate-side joining end face31aand the hub-side joining end face41a. Since the first welded portions50provided on both sides in the Z direction have the same configuration, one (the first welded portion50on the arrow Z1direction side) will be described below, and description of the other (the first welded portion50on the arrow Z2direction side) will be omitted.

As illustrated inFIG. 7, the shape of the radial cross section of the first welded portion50corresponds to the shape of a melted portion150when the end plate30and the hub member40are welded. The first welded portion50means a part that is formed by solidifying after a melted part of the end plate30and a melted part of the hub member40are mixed. That is, it is described that the heat-affected portion generated when forming the first welded portion50is not included in the first welded portion50. The heat-affected zone configures a part of the non-melted portion71of the projected portion70.

Here, in the first welded portion50, the melting ratio r of the end plate30is configured to be 40% or more and 80% or less. Specifically, in the first welded portion50, when the hub member40is formed of S25C and the end plate30is formed of SUS304, the first welded portion50is configured such that the melting ratio r of SUS304 is 40% or more and 80% or less. It is more preferable that the melting ratio r of SUS304 be larger than the melting ratio of S25C. When the end plate30is composed of SUS309, it is preferable that the melting ratio r be 20% or more and 80% or less.

Specifically, in the present embodiment, when the melted area of the end plate30in the radial cross section of the first welded portion50is S1and the melted area of the hub member40is S2, the melted area S1of the end plate30is 40% or more and 80% or less of the entire the first welded portion50(S1+S2). As in the example ofFIG. 7, it is more preferable that the melted area S1is larger than the melted area S2.

The melted area S1means an area of a part of the first welded portion50, the part being radially outward of the plate-side joining end face31a(hub-side joining end face41a). Further, the melted area S2means an area of a part of the first welded portion50, the part being radially inward of the hub-side joining end face41a(plate-side joining end face31a) of the first welded portion50.

The first welded portion50is formed so as to have a tapered shape toward the tip end portion S2on the hub member40side. In the direction (arrow Z2direction) toward the rotor core20out of the rotational axis direction, the first welded portion50has the following: a part of the end plate30in which a width W11gradually becomes smaller, the width W11being in the direction (arrow R2direction) orthogonal to the plate-side joining end face31a(hub-side joining end face surface41a) of the first welded portion50; and a part of the hub member40in which a width W12gradually becomes larger, the width W12being in the direction (arrow R1direction) orthogonal to the plate-side joining end face31a(hub-side joining end face41a) of the first welded portion50. The maximum dimension of the width W11is larger than the maximum dimension of the width W12. The rotational axis direction position at which the width W11is the maximum is positioned on the projecting direction side (arrow Z1direction side) of the projected portion70, with respect to the rotational axis direction position at which the width W12becomes the maximum.

The projected portion70is provided with a boundary portion53between the first welded portion50and the non-melted portion71. For example, the boundary portion53is provided on the inclined surface73. That is, in the projected portion70, radially inward of the boundary portion53is the first welded portion50and radially outward of the boundary portion53is the non-melted portion71.

As seen inFIG. 8, at least a part of the first welded portion50(part on the end plate30side) is formed at a position where the part overlaps with the recessed portions26in the rotational axis direction, as viewed in the rotational axis direction. As a result, the heat capacity of the projected portion70becomes smaller, corresponding to the heat being not easily transmitted to the rotor core20. In addition, it is possible to prevent the rotor core20from being heat-affected (deformed, distorted, and the like) due to the heat that is generated when forming the first welded portion50.

(Structure of Second Welded Portion: Structure of Welded Portion Between Rotor Core and Hub Member)

As illustrated inFIG. 1, a plurality of the second welded portions60are provided on both sides of the rotor100in the Z direction. That is, the second welded portions60are formed on the core end faces25aand25bof the rotor core20, across the core inner peripheral surface22aof the through whole22of the rotor core20and the outer peripheral surface41of the hub member40.

The cross section along the radial direction of the second welded portions60has a shape tapered toward the inside of the rotor core20in the rotational axis direction, and is formed in a generally triangular shape. The second welded portions60are formed across a plurality of the electromagnetic steel sheets21.

As illustrated inFIG. 2, the second welded portions60are provided so as to be spaced away from each other in the circumferential direction. The first welded portions50and the second welded portions60are provided at generally the same radial position. The second welded portions60are disposed at positions in the circumferential direction corresponding to positions between the permanent magnets23(insertion holes24) in the circumferential direction. The first welded portions50are each disposed between two adjacent second welded portions60in the circumferential direction. The second welded portions60provided on the core end face25aof the rotor core20are formed so as to be exposed via the clearance portions33as viewed from the arrow Z1direction. The second welded portions60provided on the core end face25bof the rotor core20are formed so as to be exposed via the clearance portions33as viewed from the arrow Z2direction.

[Manufacturing Method of Rotor]

Next, a manufacturing method of the rotor100according to the first embodiment will be described.FIG. 9illustrates a flowchart of a manufacturing process of the rotor100.

(Step of Preparing End Plate and Hub Member)

First, in step S1(seeFIG. 9), the end plate30and the hub member40are prepared. That is, in the present embodiment, the end plate30that is configured of an austenitic material is prepared. Here, the end plate30has the projected portions70that are each provided adjacent the plate-side joining end face31ain the radial direction and that are each projected from the bottom face32aof the depressed portion32, which is an end face in the rotational axis direction, in the direction away from the rotor core20out of the rotational axis direction.

Specifically, a steel plate of austenitic stainless steel (preferably, SUS304 or SUS309) serving as an austenitic material having the thickness t2is prepared. Then, as illustrated inFIG. 10, the depressed portion32composed of the inclined surface73, the bottom face32a, and the radially outward inclined surface32bis formed on the steel plate by a machining or a press working performed with a working device (a press working device, a machining center, and the like). A through hole is formed in the steel plate and the inner peripheral surface31(plate-side joining end faces31a) is formed. As a result, the projected portions70are formed radially inward of the steel plate.

More specifically, the inclined surface73is formed on the steel plate so as to be continuous with the top surfaces172of the projected portions70and the bottom face32aof the depressed portion32. In addition, the inclined surface73is inclined radially outward (in the direction away from the hub member40) from the top surface172with respect to the rotational axis direction. Then, by forming the depressed portion32in the steel plate, the projected portions70are each formed between the depressed portion32and the plate-side joining end face31ain the radial direction, the projected portions70projecting from the bottom face32aof the depressed portion32in the direction away from the rotor core20out of the rotational axis direction.

Here, each of the top surfaces172is formed as a flat surface that is orthogonal to the plate-side joining end face31a. The top surface172becomes the top surface72with the formation of the first welded portion50thereon. In addition, the bent portion34(seeFIG. 10) is formed by the press working device.

As illustrated inFIG. 4, the clearance portions33, which are depressed radially outward from the plate-side joining end faces31a, are each formed on the steel plate at a position adjacent to the projected portion70in the circumferential direction by a press working device or a machining device. The bent portion34(seeFIG. 10) is formed by the press working device and the end plate30is formed (prepared).

As illustrated inFIG. 1, the hub member40composed of a martensitic material is prepared. Specifically, the hub member40composed of carbon steel (for example, S25C or S35C) serving as a martensitic material is prepared. The hub member40is prepared, which includes the outer peripheral surface41that is formed to have a cylindrical shape, that has the hub-side joining end faces41a, and that is provided with the heat releasing portions41b(seeFIG. 6) formed to be flush with (having the same radial position as) the hub-side joining end faces41aand continuous toward the outer side in the rotational axis direction.

(Step of Preparing Rotor Core)

In step S2, the rotor core20is formed (prepared). Specifically, the magnetic steel plates21are punched from a strip-shaped magnetic steel plate by a press working device. As illustrated inFIG. 3, the electromagnetic steel plates21each having an annular shape are stacked in the rotational axis rotation that is the extending direction of the rotational axis. In this way, the cylindrical electromagnetic steel plates21are formed, the electromagnetic steel plates21being rotated around the rotational axis and having the through hole22with the rotational axis C as the center.

Then, the stacked electromagnetic steel sheets21are welded. Specifically, the protruded portions27of the magnetic steel sheets21are melted by inputting heat to the top portion of the protruded portions27. When the melted part solidifies, the core forming welded portions28are formed in the protruded portions27. In this way, the rotor core20is formed (prepared). Welding is performed, for example, by emitting a high-energy beam (laser or electron beam) from a heat source device200(seeFIG. 12) so as to input heat to the protruded portions27.

(Step of Inserting Permanent Magnet)

In step S3, the permanent magnet23is inserted in each of the insertion holes24of the rotor core20. For example, the permanent magnet23is inserted into the insertion hole24by moving the permanent magnet23in the rotational axis direction with respect to the rotor core20.

(Step of Disposing End Plate)

As illustrated inFIG. 11, in step S4, the end plate30is disposed on each of the core end face25aand the core end face25bthat are the end portions of the rotor core20in the rotational axis direction, the end plate30having the inner peripheral surface31(through hole) with the rotational axis C as the center. At this time, as viewed from the outside in the rotational axis direction, a part of the core end face25aor a part of the core end face25bis exposed via the clearance portions33of the end plate30(seeFIG. 8). The core end faces25aand25bare covered by a part other than the clearance portions33of the end plate30.

As illustrated inFIG. 11, in step S5, the hub member40is disposed on the inner peripheral surface31(plate-side joining end faces31a) of the end plate30. Specifically, the hub member40is disposed so that the outer peripheral surface41of the hub member40faces in the radial direction, the inner peripheral surface31(plate-side joining end faces31a), which is formed as the through hole, and the through hole22of the rotor core20. For example, the hub member40, the end plate30, and the rotor core20are relatively moved in the rotational axis direction.

(Step of Forming First Welded Portion)

As illustrated inFIG. 12, in the present embodiment, in step S6, at least a part of the projected portion70is melted so that the first welded portion50is formed across the projected portion70of the end plate30, the plate-side joining end face31a, and the hub member40. For example, a part of the hub member40composed of carbon steel serving as a martensitic material and at least a part of the projected portion70, which is composed of austenitic stainless steel serving as an austenitic material, of the end plate30are melted so that the first welded portion50is formed.

Specifically, the high-energy beam G (hereinafter referred to as the “beam G”) is emitted on the top surface172of the projected portion70in the rotational axis direction by the heat source device200so that at least a part of the projected portion70is melted so as to form the melted portion150extending from the projected portion70to the hub member40. Then, the melted part is solidified to form the first welded portion50. It is preferable that the beam G be a laser beam and the heat source device200be a light source device. The heat source device200is configured to perform keyhole welding for forming a keyhole, when forming the melted portion150.

More specifically, the heat source device200emits the beam G on the top surface172so that a beam center C1of the beam G is positioned at a position P1offset radially outward (to the end plate30side) from the plate-side joining end face31aby a distance D1(offset amount D1), and so that an emission direction F1of the beam G is inclined radially inward (toward the hub member40) from the radially outer side with respect to the rotational axis C direction. For example, the emission direction F1is set to an inclination angle of 15 to 20 degrees with respect to the rotational axis C. In this way, as illustrated inFIG. 7, in the present embodiment, the melted portion150is formed so that the width W11of the melted portion150of the end plate30in the direction orthogonal to the plate-side joining end face31ais gradually decreased, and so that the width W12of the melted portion150of the hub member40in the direction orthogonal to the plate-side joining end face31ais gradually increased, in the direction toward the rotor core20out of the rotational axis direction.

Here, the beam G is emitted on the top surface172of the projected portion70having a width W21in the radial direction larger than a beam diameter φ of the beam G. As illustrated inFIG. 13, the width W21is preferably 0.8×φ or more (more preferably, 2.0×φ or more). For example, the width W21is 2.0×φ or more and 3.0φ or less.

The width W21is larger than a dimension obtained by adding a beam diameter (φ/2) to a dimension of three halves of the offset amount D1(D1×3/2). That is, W21>(D1×3/2)+(φ/2). Thus, the width W21allows accepting the magnitude of the error of the emission position (position P1) of the beam G, and the dimensional error of the end plate30and the hub member40. For example, the width W21of top surface172and the width W1of the top surface72are the same.

The beam G is emitted on the top surface172that is formed as a flat surface orthogonal to the plate-side joining end face31a. Thus, the top surface172is deformed into the top surface72so that the top surface172is inclined radially inward (toward the hub member40) in a direction away from the rotor core20out of the rotational axis direction.

In the present embodiment, a part of the hub member40composed of S25C serving as a martensitic material and at least a part of the projected portion70of the end plate30composed of SUS304 serving as an austenitic material are melted. Thus, the first welded portion50is formed so that the melted area S1of the end plate30in the radial section (seeFIG. 7) of the first welded portion50is 40% or more and 80% or less of the radial section.

In the present embodiment, the heat input to the projected portion70is transmitted to the heat releasing portion41b. Here, the heat releasing portion41bis formed to be continuous and in flush with the hub-side joining end faces41aof the outer peripheral surface41that faces the inner peripheral surface31of the end plate30, toward the direction away from the rotor core20out of the rotational axis direction. In this way, the heat in the hub member40is transmitted to the heat releasing portion41b.

As illustrated inFIG. 8, the first welded portion50is formed with the projected portion70and the recessed portions26overlapped, as viewed in the rotational axis direction.

(Step of Forming Second Welded Portion)

In step S7, the second welded portions60are formed. In the present embodiment, as illustrated inFIG. 8, the second welded portion60is formed by melting the rotor core20and the hub member40, while a part of the core end face25aor a part of the core end face25bof the rotor core20is exposed via the clearance portion33, in the direction away from the rotor core20out of the rotational axis direction (outward in the rotational axis direction).

Specifically, the beam G is emitted on the core end faces25aand25bexposed via the clearance portion33. In this way, the second welded portion60is formed so as to sandwich the first welded portion50in the circumferential direction so that the radial position is generally the same as that of the first welded portion50. The beam G is emitted by the heat source device200that forms the first welded portion50. Then, when the rotor100is completed and combined with the stator10, the rotating electrical machine101is completed.

[Comparison Result of Formation of First Welded Portion]

As illustrated inFIG. 13, a description will be provided of a comparison result of a first welded portion forming method according to a comparative example in which a hub member and an end plate that is not provided with projected portions are welded to form the first welded portions, and the first welded portion50forming method according to the present embodiment. The first welded portion forming method (in particular, setting the offset amount) according to the comparative example does not indicate a conventional technique, but is an example for showing the effects of the present embodiment.

Evaluation was performed for the welded part of the first welded portion according to the comparative example in which the offset amount D1of the beam G is set to 0 (no offset), 0.4×φ, 0.8×φ, 1.2×φ, and 1.6×φ, and the welded part of the first welded portion50according to the present embodiment. For the first welded portions50according to the present embodiment, evaluation was performed for the cases where the width W21of the top surface172is set to 0.8×φ and 2.0×φ. The evaluation “∘” means that joining strength is ensured and that low-temperature cracking or non-welding has not occurred, and the evaluation “×” means that joining strength is not easily ensured (low temperature cracking or non-welding has occurred).

As a result of the evaluation, in the comparative example, the evaluation is as follows: “×” when the offset amount D1is 0; “×” when 0.4×φ; “∘” when 0.8×φ; “∘” when 1.2×φ; and “×” when 1.6×φ.

When the width W21of the present embodiment is 0.8×φ, the evaluation is as follows: “∘” when the offset amount D1is 0; “∘” when 0.4×φ; “∘” when 0.8×φ; “×” when 1.2×φ; and “×” when 1.6×φ. When the width W21of the present embodiment is 2.0×φ, the evaluation is as follows: “∘” when the offset amount D1is 0; “∘” when 0.4×φ; “∘” when 0.8×φ; “∘” when 1.2×φ; and “×” when 1.6×φ.

As a result of comparison between the comparative example and the present embodiment, it is found that in the comparative example, joining strength can be ensured when the offset amount D1is 0.8×φ or more and 1.2×φ or less, and in contrast, in the present embodiment, joining strength can be ensured when the offset amount D1is 0 or more and 0.8×φ or less (1.2×φ when W21is 2.0×φ, which is a wider range than the comparative example. That is, it has been found that compared to the comparative example, the present embodiment has a wider allowable range for an error of the offset amount D1(the emission position error of the beam G or the dimensional error of the end plate30).

As a result of comparing the case where the width W21of the present embodiment is 0.8×φ and the case where the width W21of the present embodiment is 2.0×φ, the range of the offset amount D1is wider in the case of 2.0×φ. That is, it has been found that when the width W21of the present embodiment is 2.0×φ, the allowable range of the offset amount D1becomes wider.

[Evaluation Result of Melting Ratio of First Welded Portion]

With reference toFIG. 14, a description will be given regarding a result of changing the melting ratio r (melting ratio r of SUS304) of the end plate30and evaluating the welded part of the first welded portion50according to the present embodiment. The hub member40used was composed of S25C.

As a result of the evaluation, low-temperature cracking (“×”) occurs when the melting ratio r is 30%, as illustrated inFIG. 14. It was found that joining strength of the first welded portion50can be ensured (“∘”) in a range where the melting ratio r is 40% or more and 80% or less. It was also found that non-welding (“×”) occurs when the melting ratio r is 90%.

As a result, it was found that joining strength of the first welded portion50can be surely ensured when SUS304 is used as the end plate30and S25C is used as the hub member40, and when the melting ratio r is 40% or more and 80% or less.

[Effects of Manufacturing Method of Present Embodiment]

In the manufacturing method according to the present embodiment, the following effects can be obtained.

In the above embodiment, as described above, the welded portion (50) is formed across the projected portion (70) of the plate (30) and the rotation transmitting member (40) by melting at least part of the projected portion (70). In this way, the heat capacity of the projected portion (70) (the part of the plate (30) to be melted) can be made smaller than when the part of the plate (30) to be melted is formed as a surface that is not projected. As a result, the melting amount of the plate (30) composed of an austenitic material can be increased, compared to when the projected portion (70) is not provided. Thus, the melting ratio (r) of the austenitic material in the welded portion (50) can be increased. Therefore, it is possible to make low-temperature cracking is less likely to occur in the welded portion (50) and it is possible to ensure joining strength even when the plate (30) is welded and fixed to the rotation transmitting member (40) composed of a martensitic material. In the above embodiment, since the projected portion (70) composed of the austenitic material provided on the plate (30) beforehand can be melted, it is possible to increase the melting ratio (r) of the austenite material in the welded portion (50) without providing a device for supplying a welding wire or the like in the manufacturing equipment of the rotor (100). As a result, joining strength between the rotation transmitting member (40) and the plate (30) can be ensured while preventing the manufacturing equipment (welding equipment) of the rotor (100) from increasing in size.

In the above embodiment, the step (S5) of disposing the rotation transmitting member (40) is the step (S5) of disposing the rotation transmitting member (40) so that an inner wall surface (31a) radially inward of the projected portion (70) faces an outer diameter surface (41a) of the rotation transmitting member (40) in the radial direction; and the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) across the inner wall surface (31a) of the projected portion (70) and the outer diameter surface (41a) of the rotation transmitting member (40). With such a configuration, the projected portion and the rotation transmitting member can be directly joined thereacross, and thus joining strength between the rotation transmitting member (40) and the plate (30) can be further ensured.

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by melting a part of the rotation transmitting member (40) that is formed of carbon steel serving as the martensitic material and at least a part of the projected portion (70) of the plate (30) that is formed of austenitic stainless steel serving as the austenitic material. With such a configuration, carbon steel that is generally used as a material of the rotation transmitting member (40) and austenitic stainless steel that is generally used as a material of the plate (30) can be used. As a result, it is not necessary to form the rotation transmitting member (40) and the plate (30) with a special material and thus, joining strength of the rotation transmitting member (40) and the plate (30) can be ensured while using versatile materials.

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by emitting the energy beam (G) on the top surface (172) of the projected portion (70) in the rotational axis direction so as to melt at least a part of the projected portion (70) so as to form the melted portion (150) extending from the projected portion (70) to the rotation transmitting member (40). With such a configuration, melting can be started from the top surface (172) of the projected portion (70) composed of austenitic material, so that the melting ratio (r) of the austenitic material of the welded portion (50) can be easily increased, unlike the case where melting is started from the rotation transmitting member (40) composed of martensitic material. Since the energy beam (G) is emitted to form the welded portion (50), the shape of the melted portion (150) to be formed can be easily controlled according to the direction in which the energy beam (G) is emitted. As a result, the shape of the welded portion (50) can be easily controlled, unlike with arc welding, which is not welding (keyhole welding) performed by emitting the energy beam (G).

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by emitting the energy beam (G) on the top surface (172) so that the beam center (C1) of the energy beam (G) is positioned at the position (P1) offset from the rotation transmitting member (40) to the plate (30) side in the radial direction and so that the emission direction of the energy beam (G) is inclined from the plate (30) side toward the rotation transmitting member (40) with respect to the rotational axis direction. With such a configuration, heat can be input while the emission position (P1) of the energy beam (G) is offset from the rotation transmitting member (40) toward the plate (30). Thus, the melting ratio (r) of the austenitic material in the welded portion (50) can be further increased. Further, by inclining the emission direction of the energy beam (G) from the plate (30) side in the radial direction toward the rotation transmitting member (40) in the radial direction, it is possible to easily form the melted portion (150) extending from the plate (30) to the rotation transmitting member (40), even when the emission position (P1) of the energy beam (G) is offset.

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by forming the melted portion (150) so that the width (W11) of the melted portion (150) of the plate (30) in the radial direction becomes gradually smaller and the width (W12) of the melted portion (150) of the rotation transmitting member (40) in the radial direction becomes gradually larger, in the direction toward the rotor core (20) out of the rotational axis direction. With such a configuration, it is possible to increase the melting amount of the plate (30) composed of austenitic material at a position relatively far from the rotor core (20) and decrease the melting amount of the plate (30) at a position relatively close to the rotor core (20). As a result, it is possible to reduce the effect of heat on the rotor core (20) when the plate (30) is melted.

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by emitting the energy beam (G) on the top surface (172) of the projected portion (70) that has the width (W21) in the radial direction larger than the beam diameter (φ) of the energy beam (G). Here, if the emission position (P1) of the energy beam (G) is the side face of the projected portion (70) that is a part other than the top surface (172) of the projected portion (70) when there is an error in the emission position (P1) of the energy beam (G) or there is an error in the dimension of the plate (30) or the rotation transmitting member (40), it is conceivable that the energy beam (G) on the emission part is scattered or the reflection is increased and thus the power density in the emission part is decreased. In this case, it is conceivable that since the power density in the emission part is reduced, the melted amount of the entire welded portion (50) is reduced, and joining strength between the rotation transmitting member (40) and the plate (30) is not easily ensured. In contrast, with the above configuration, even if there is an error in the emission position (P1) of the energy beam (G) or a dimensional error in the plate (30) and the rotation transmitting member (40), it is possible to prevent the emission position (P1) of the energy beam (G) from deviating from the top surface (172) of the projected portion (70). As a result, it is possible to prevent the power density in the emission part from decreasing and thus, it is possible to surely ensure joining strength between the rotation transmitting member (40) and the plate (30).

In the above embodiment, as described above, the step (S1) (S1) of preparing the plate (30) is the step (S1) of preparing the plate (30) having the inclined surface (73) that is formed so as to be continuous with the top surface (172) of the projected portion (70) and the end face (32a) in the rotational axis direction and that is inclined from the top surface (172) in the direction away from the rotation transmitting member (40) in the radial direction with respect to the rotational axis direction. Here, in the case where the top surface (172) of the projected portion (70) and the end face (32a) in the rotational axis direction are connected by the side face extended in the rotational axis direction, when the emission position (P1) of the energy beam (G) is deviated (moved) from the top surface (172) of the projected portion (70) to the side face, an incident angle of the energy beam (G) with respect to the side face becomes small and the reflection and scatter of the energy beam (G) on the side face is increased. In contrast, with the above configuration, even if the emission position (P1) of the energy beam (G) deviates from the top surface (172) of the projected portion (70) to the inclined surface (73), the decrease margin of the incident angle of the energy beam (G) with respect to the inclined surface (73) becomes small and thus, it is possible decrease reflection and scatter of the energy beam (G). As a result, even if there is an error in the emission position (P1) of the energy beam (G) or a dimensional error of the plate (30) and the rotation transmitting member (40), it is possible to further prevent the power density in the emission part of the energy beam (G) from being reduced.

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by emitting the energy beam (G) on the top surface (172) formed as a flat surface orthogonal to the rotational axis so as to deform the top surface (172) (into72) so that the top surface (172) is inclined toward the rotation transmitting member (40) in the radial direction as the top surface (172) is inclined toward the direction away from the rotor core (20) out of the rotational axis direction. With such a configuration, by deforming the top surface (172), it is possible to increase the length in the rotational axis direction of the part in which the plate (30) and the rotation transmitting member (40) are joined and thus, further ensure joining strength of the plate (30) and the rotation transmitting member (40).

Further, in the above embodiment, as described above, the step (S1) of preparing the plate (30) is the step (S1) of preparing the plate (30) by forming the depressed portion (32) depressed in the rotational axis direction as the part (32) having the width (t4) in the rotational axis direction smaller than the width (t2) of the projected portion (70) in the rotational axis direction, so as to form the projected portion (70), which is projected from the bottom face (32a) of the depressed portion (32) serving as the end face (32a) in the rotational axis direction toward the direction away from the rotor core (20) out of the rotational axis direction, between the depressed portion (32) and the inner wall surface (31a) radially inward in the radial direction. With such a configuration, by preparing a plate member (steel plate) composed of an austenitic material having the fixed thickness (t2) in the rotational axis direction to form the depressed portion (32), it is possible to easily form the plate (30) that is provided with the projected portion (70).

In the above embodiment, as described above, the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) by melting the part of the rotation transmitting member (40) that is formed of S25C serving as the martensitic material and at least the part of the projected portion (70) of the plate (30) that is formed of SUS304 serving as the austenitic material, so that the melted area (S1) of the plate (30) in the radial section of the welded portion (50) is 40% or more and 80% or less of the radial section. With such a configuration, low-temperature cracking of the welded portion (50) can be made less likely to occur. The effect has been confirmed by the above measurement results.

In the above embodiment, as described above, the step (S5) of disposing the rotation transmitting member (40) is the step (S5) of disposing the rotation transmitting member (40) so that the outer diameter surface of the rotation transmitting member (40) formed as the hub member (40) that is extended in the rotational axis direction faces the inner wall surface (31a) of the plate (30) formed as the through hole in the radial direction, and the step (S6) of forming the welded portion (50) is the step (S6) of forming the welded portion (50) so that heat input to the projected portion (70) is transmitted to the heat releasing portion (41b) that is formed to be continuous and in flush with the facing surface (41a), which faces the inner wall surface (31a), out of the outer diameter surface (41), toward the direction away from the rotor core (20) out of the rotational axis direction. With such a configuration, since the heat transmitted to the hub member (40) can be transmitted to the heat releasing portion (41b), it is possible to reduce the melting ratio of the welded portion (50) in the hub portion (40) material composed of martensitic material. As a result, the melting ratio (r) of the plate (30) composed of the austenitic material in the welded portion (50) can be increased, so that joining strength of the plate (30) and the rotation transmitting member (40) can be ensured.

In the above embodiment, as described above, the step (S1) of preparing the plate (30) is the step (S1) of preparing the plate (30) having the core welding clearance portion (33) that is depressed from the end face (31a) of the plate (30) on one side in the radial direction to the other side in the radial direction at the position adjacent to the projected portion (70) in the circumferential direction, and the manufacturing method further includes the step (S6) of forming the core welded portion (50) by melting the rotor core (20) and the rotation transmitting member (40) while a part (25a,25b) of the rotor core (20) is exposed in the direction away from the rotor core (20) out of the rotational axis direction via the core welding clearance portion (33). With such a configuration, the rotor core (20) and the rotation transmitting member (40) can be welded while the plate (30) is disposed on the end face (32a) of the rotor core (20) in the rotational axis direction. As a result, since the step (S7) of forming the core welded portion (60) and the step (S6) of forming the welded portion (50) can be performed continuously, it is possible to perform the step (S6) of forming the welded portion (50), without retracting the heat source device (200) from the vicinity of the rotor (100) (rotation transmitting member (40)), after the step (S6) of forming the core welded portion (50). As a result, it is possible to prevent the manufacturing process of the rotor (100) from being complicated.

The embodiment disclosed herein is by way of example in all respects and should not be interpreted as restrictive. The scope of the present disclosure is defined by the scope of the claims, rather than the description of the above embodiment, and includes the scope of claims and all changes (modifications) within the meaning and scope equivalence.

For example, in the above embodiment, an example is described in which the rotor is configured as an inner rotor. However, the present disclosure is not limited to this. That is, the rotor may be configured as an outer rotor.

In the above embodiment, an example is described in which the welded portions are formed between the hub member and the end plate. However, the present disclosure is not limited to this. For example, the welded portions may be formed between the shaft member serving as the rotation transmitting member and the end plate, without providing the hub member.

In the above embodiment, stainless steel (SUS304 and SUS309) is indicated as the austenitic material forming the end plate. However, the present disclosure is not limited to this. That is, the material forming the end plate only needs to have an austenitic structure, and the end plate may be formed of an austenitic material other than austenitic stainless steel.

In the above embodiment, carbon steel (S25C and S35C) is indicated as the martensitic material for the hub member. However, the present disclosure is not limited to this. That is, the material forming the hub member only needs to have a martensitic structure, and the hub member may be formed of a martensitic material other than martensitic carbon steel.

In the above embodiment, an example is described in which the boundary portion of the first welded portion is provided on the inclined surface of the projected portion. However, the present disclosure is not limited to this. For example, as in a rotor300according to a first modification illustrated inFIG. 15, a boundary portion353of a first welded portion350may be provided on the top surface172of a projected portion370. In this case, by forming the first welded portion350, a part of the top surface172of the projected portion370becomes the top surface72having a shape with excess weld material and the other portion of the top surface172becomes a flat surface.

In the above embodiment, an example is described in which the projected portion is provided with the surface inclined at 30 degrees or more and 60 degrees or less. However, the present disclosure is not limited to this. For example, as in an end plate430according to a second modified example illustrated inFIG. 16, a side face473that is a radially outward side face of a projected portion470and an inner side face of a depressed portion432may be formed generally in parallel with the rotational axis direction. The side face473is formed so as to connect a top surface472and a bottom face432a.

In the above embodiment, an example is described in which the depressed portion is formed in the end plate to form the projected portion in the end plate. However, the present disclosure is not limited to this. For example, as in an end plate530according to a third modified example illustrated inFIG. 17, a projected portion570protruding from an end face530ain the rotational axis direction of the end plate530may be formed without forming a depressed portion. For example, an inclined surface573is formed so as to connect a top surface572and an end face530a(a part having a width in the rotational axis direction smaller than the width of the projected portion570in the rotational axis direction).

In the above embodiment, an example is described in which the energy beam is emitted on the top surface while the beam center of the energy beam is positioned at a position offset to the end plate side in the radial direction from the plate-side joining end face, and the emission direction of the energy beam is inclined with respect to the rotational axis direction. However, the present disclosure is not limited to this. For example, when the end plate and the hub member are formed nearly flush along the radial direction, the energy beam may be emitted along the rotational axis direction without the beam center being offset. If the beam center is positioned at the position offset to the end plate side as in the above embodiment, it is possible to effectively increase the melting ratio of the end plate.

In the above embodiment, an example is described in which the width of the top surface in the radial direction is set to be larger than the beam diameter of the energy beam. However, the present disclosure is not limited to this. For example, the top surface may be configured to have a radial width that is the beam diameter of the energy beam or less. As in the above embodiment, since reflection and scattering are prevented when the width of the top surface in the radial direction is set to be larger than the beam diameter of the energy beam, the energy beam can be efficiently emitted on the projected portion.

In the above embodiment, an example is described in which the radial cross section of the inclined surface is formed to be linear. However, the present disclosure is not limited to this. For example, the inclined surface may be formed so that the radial cross section has an arc shape.

In the above embodiment, an example is described in which the heat releasing portion is provided in the hub member. However, the present disclosure is not limited to this. For example, the heat releasing portion does not have to be provided, if it is possible to sufficiently ensure the melting ratio of the end plate in the first welded portion without providing the heat releasing portion on the hub member by providing the projected portion in the end plate.

In the above embodiment, an example is described in which the clearance portion is formed as the recessed portion. However, the present disclosure is not limited to this. That is, the clearance portion need only be configured so that the rotor core and the hub member can be welded via the clearance portion. For example, the clearance portion may be formed as a through hole.

In the above embodiment, an example is described in which the step of forming the second welded portion is performed after the step of forming the first welded portion. However, the present disclosure is not limited to this. That is, the step of forming the first welded portion may be performed after the step of forming the second welded portion, or the step of forming the first welded portion and the step of forming the second welded portion may be performed alternately.

In the above embodiment, an example is described in which the end plates are disposed radially outward of the hub member (the hub member is disposed radially inward of the end plates). However, the present disclosure is not limited to this. That is, the end plates may be disposed radially inward of the hub member (the hub member may be disposed radially outward of the end plates).

In the above embodiment, an example is described in which the plate of the present disclosure is applied to the end plate. However, the present disclosure is not limited to this. That is, the plate of the present disclosure may be applied to a plate other than the end plate.

DESCRIPTION OF THE REFERENCE NUMERALS

32,432Depressed portion (part having width in rotational axis direction smaller than width of projected portion in rotational axis direction)

32a,432aBottom face (end face in rotational axis direction)

41aHub-side joining end face (facing surface of outer diameter surface)

530aEnd face (part having width in rotational axis direction smaller than width of projected portion in rotational axis direction)