Positioning method and jig

Abstract

The present invention provides a positioning method and a jig that enable accurate phase setting of a plurality of iron core pieces. Provided is a positioning method for a rotor core 3 formed by laminating a plurality of core pieces 1 each having a key portion 9. In this method, a fixed abutting portion 13 and a rotating abutting portion 15 which can separately abut one side and the other side of the key portion 9 in the circumferential direction are rotated relative to each other, the relative rotation causes the key portion 9 to rotate and move relatively in the circumferential direction between the fixed abutting portion 13 and the rotating abutting portion 15, and the fixed abutting portion 13 and the rotating abutting portion 15 are respectively caused to abut the one side and the other side, in the circumferential direction, of the key portion 9 of each core piece 1 to sandwich the key portion 9 between the fixed abutting portion 13 and the rotating abutting portion 15, thereby aligning the phases of the laminated core pieces 1.

Description

Positioning method and jig

[0001] The present invention relates to a positioning method and a jig for aligning the phases of a plurality of core pieces to form a laminated core.

[0002] Conventional positioning methods include, as disclosed in Patent Document 1, aligning the phases of steel plates in a rotor core, which is a laminated core formed by laminating steel plates that are a plurality of core pieces formed by pressing.

[0003] In this method, the insertion part is loosely fitted into the central hole of the rotor core, and then the insertion part is rotated around the axis relative to the rotor core. As a result, one side surface formed on the insertion part comes into contact with and presses against the key portions of the multiple steel plates of the rotor core in the circumferential direction, aligning the key portions in the axial direction while rotating the multiple steel plates. In this way, the phases of the multiple steel plates are aligned and positioned.

[0004] However, with this positioning method, the steel plates may stick to each other due to press oil or the like, and the stuck steel plates inevitably rotate together. This co-rotation can make it difficult to position the multiple steel plates so that their phases are aligned.

[0005] Japanese Patent Application Laid-Open No. 2021-136756

[0006] The problem to be solved is that it can be difficult to position a plurality of laminated core pieces so that the phases of the pieces are aligned.

[0007] The present invention provides a positioning method for aligning the phases of multiple stacked core pieces having circumferential engaging portions. This positioning method involves relatively rotating first and second abutment portions that can abut on one and the other sides of the engaging portions in the circumferential direction, respectively, and relatively moving the engaging portions in the circumferential direction between the first and second abutment portions due to the relative rotation. Then, the first and second abutment portions abut on one and the other sides of the engaging portions of each core piece in the circumferential direction, respectively, to sandwich the engaging portions between the first and second abutment portions, thereby aligning the phases of the stacked multiple core pieces.

[0008] The present invention also provides a jig for aligning the phase of a plurality of stacked core pieces, each having a circumferential engaging portion and a central hole, the jig including first and second abutment portions that are arranged coaxially and rotatably relative to one another and that axially fit into the central holes of the stacked core pieces, and a space portion that positions the engaging portion between the first and second abutment portions in the circumferential direction and allows the relative rotation of the first and second abutment portions.

[0009] The present invention can reliably position a plurality of laminated core pieces so that the phases of the core pieces are aligned.

[0010] FIG. 1 is a perspective view of a rotor core according to a first embodiment of the present invention. FIG. 2 is an enlarged plan view showing a phase shift around the center hole of the rotor core of FIG. 1. FIG. 3 is an enlarged plan view showing the periphery of the center hole of the rotor core of FIG. 1 with a jig installed. FIG. 4 is an enlarged plan view showing the periphery of the center hole of the rotor core of FIG. 1 in a positioning state using the jig. FIG. 5 is a perspective view of the jig of FIG. 3. FIG. 6 is a front view of the jig of FIG. 5. FIG. 7 is a plan view of the jig of FIG. 5. FIG. 8 is an enlarged front view showing a portion of the jig of FIG. 5. FIG. 9 is an enlarged plan view showing a portion of the jig of FIG. 5. FIG. 10 is an enlarged plan view showing the periphery of the center hole of the rotor core with the jig installed according to a second embodiment of the present invention. FIG. 11 is an enlarged plan view showing the periphery of the center hole of the rotor core in a positioning state according to the second embodiment of the present invention.

[0011] The objective of reliably positioning the laminated core pieces so that the phases of the core pieces are aligned is achieved by sandwiching the engaging portions of the core pieces between the first and second abutment portions from both sides in the circumferential direction.

[0012] The positioning method aligns the phase of a plurality of stacked core pieces 1 each having a circumferential engaging portion 9. In this positioning method, first and second abutment portions 13 and 15, which can abut against one and the other circumferential sides of the engaging portion 9, are rotated relative to one another, and the engaging portion 9 is moved relatively in the circumferential direction between the first and second abutment portions 13 and 15. Then, the first and second abutment portions 13 and 15 are abutted against one and the other circumferential sides of the engaging portion 9 of each core piece 1, respectively, to sandwich the engaging portion 9 between the first and second abutment portions 13 and 15, thereby aligning the phase of the stacked plurality of core pieces 1.

[0013] The first and second contact portions 13 and 15 may be provided so as to be rotatable relative to each other about the same axis. In this case, the first and second contact portions 13 and 15 may be attached to the stacked core pieces 1 and rotated relative to each other about the same axis, and may be brought into contact with one side and the other side of the engaging portion 9 in the circumferential direction, respectively.

[0014] When the core piece 1 has a central hole 5 with the engaging portion 9 protruding radially inward, the first and second abutment portions 13 and 15 may be fitted into the central hole 9 and rotated relative to each other.

[0015] One 15 of the first and second abutment portions 13 and 15 may be coupled to a shaft portion 23 that serves as the center of relative rotation, and the other 13 of the first and second abutment portions 13 and 15 may be arranged around the shaft portion 23 and be movable along the radial direction within a range that allows for abutment. In this case, the other 13 of the first and second abutment portions 13 and 15 may be pressed against the central holes 5 of the stacked multiple core pieces 1 depending on the circumferential shape of the shaft portion 23 in response to relative rotation, thereby positioning the multiple core pieces 1 in the radial direction.

[0016] The jig 17 used in the positioning method of the present invention may be configured to include first and second contact portions 13 and 15 and a space 33. The space 33 allows the engagement portion 9 to be disposed between the first and second contact portions 13 and 15 in the circumferential direction, thereby allowing the first and second contact portions 13 and 15 to rotate relative to each other.

[0017] The jig 17 may have a shaft portion 23, and one 15 of the first and second abutment portions 13 and 15 may be connected to the shaft portion 23, which serves as the center of relative rotation, and the other 13 of the first and second abutment portions 13 and 15 may be arranged to be able to rotate relatively around the shaft portion 23.

[0018] [Rotor Core] Fig. 1 is a perspective view of a rotor core according to a first embodiment of the present invention, Fig. 2 is an enlarged plan view showing a phase shift around the center hole of the rotor core in Fig. 1 .

[0019] The rotor core 3, which is a laminated core in Fig. 1, is a laminated body in which a plurality of core laminations 1, which are iron core laminations, are stacked in the axial direction, and the core laminations 1 are not bonded to each other. Note that a block in which a plurality of core laminations 1 are stacked may also be used as the laminated core of the present invention. The block is a laminated body of iron core laminations that are stacked in multiple layers to form the rotor core 3.

[0020] The core piece 1 is a plate-like body of a predetermined shape, for example, punched out of a silicon steel plate or the like by a press. The planar shape of the core piece 1 is ring-shaped, and in addition to a center hole 5, it has holes such as a magnet accommodating hole 7. The center hole 5 is circular around a center C.

[0021] A pair of key portions 9, which are engaging portions in this embodiment, protrude radially inward from the inner peripheral surface of the center hole 5. The radial direction is the direction along the diameter of the core piece 1. The pair of key portions 9 are rectangular convex portions in a plan view, with their tips facing each other radially across the center. These key portions 9 protrude radially inward from the inner peripheral surface of the center hole 5, allowing them to engage with a jig 17, described later, in the circumferential direction. In principle, only one key portion 9 is required as an engaging portion. The circumferential direction is the direction around the center of the core piece 1.

[0022] On both circumferential sides of each key portion 9, radial recesses 11 are formed on the inner periphery of the central hole 5. The recesses 11 enlarge the central hole 5 radially outward on both sides of the key portion 9.

[0023] In such a rotor core 3, if the core pieces 1 are not joined together without crimping or the like, the multiple core pieces 1 may be stacked out of phase with each other. For this reason, the phase shift of the core pieces 1 is corrected before other processes such as the magnet housing process and resin molding process are carried out. Note that when multiple blocks are stacked, the blocks may be stacked out of phase with each other.

[0024] 2 shows a stacked state in which multiple core pieces 1 are out of phase with each other, with the key portions 9 of the lower layers being shifted to one side in the circumferential direction relative to the key portions 9 of the top core piece 1. However, the phase shift is not limited to the state shown in FIG. 2 , and there are various other modes in which multiple core pieces 1 are not aligned in the axial direction. For example, the key portions 9 of the lower layers may be shifted to both sides in the circumferential direction relative to the top core piece 1.

[0025] [Positioning method] Fig. 3 is an enlarged plan view showing the state in which a jig 17 is installed, showing the periphery of the central hole 5 of the rotor core 3 in Fig. 1. Fig. 4 is an enlarged plan view showing the periphery of the central hole 5 of the rotor core 3 in Fig. 1, showing the state in which positioning is performed using the jig 17. In Figs. 3 and 4, the fixed contact portion 13 and the rotary contact portion 15 are indicated by hatching for ease of understanding.

[0026] In the positioning method of this embodiment, as shown in Figures 3 and 4, multiple core laminations 1 having key portions 9 on their inner peripheries as circumferential engaging portions are stacked and positioned to align their phases. However, the core laminations to be positioned may also be, for example, core laminations of a stator core having protrusions on their outer peripheries. In addition, in this embodiment, the multiple stacked core laminations 1 are rotor cores 3. However, the multiple stacked core laminations 1 may also be blocks as described above, or a stack of core laminations 1 that are neither rotor cores 3 nor blocks.

[0027] This positioning method can also be applied to other core pieces that have an engaging portion that can engage circumferentially on the inner or outer periphery. The shape of the engaging portion is not limited to a radial protrusion like the key portion 9, and may be a recess. In the case of a recess, the fixed abutment portion 13 and the rotary abutment portion 15 rotate relative to each other within the recess that is the engaging portion.

[0028] In the positioning method of this embodiment, first, the fixed contact portion 13 and the rotary contact portion 15, which serve as the first and second contact portions, are mounted and positioned within the central hole 5 of the rotor core 3. As a result, the fixed contact portion 13, the rotary contact portion 15, and the multiple core pieces 1 are positioned concentrically.

[0029] In this state, the fixed contact portion 13 and the rotary contact portion 15 can each contact the key portion 9. That is, at least a portion of the fixed contact portion 13 and the rotary contact portion 15 is located on the same imaginary circle as the key portion 9.

[0030] 3 shows a state in which the fixed abutment portion 13 abuts against one side of the key portion 9 of the uppermost core piece 1. However, depending on the phase shift state, the core piece 1 in the lower layer may also abut against the fixed abutment portion 13. In other words, depending on the shift of the multiple core pieces 1, the fixed abutment portion 13 will abut against the key portion 9 located at the circumferentially most one side.

[0031] The fixed abutment portion 13 and the rotary abutment portion 15 are then rotated relative to each other about the same axis to abut against one circumferential side and the other circumferential side of the key portions 9 of the multiple core pieces 1. In this embodiment, the rotary abutment portion 15 rotates relative to the fixed abutment portion 13 that is fixed in the circumferential direction. However, both the first and second abutment portions may be rotary abutment portions that rotate.

[0032] This rotation causes the rotary abutment portion 15 to rotate relative to the fixed abutment portion 13, causing one circumferential side of the key portion 9 to be received by one side surface 13a of the fixed abutment portion 13, and one side surface 15a of the rotary abutment portion 15 pushing the out-of-phase key portion 9 in the rotational direction.

[0033] Therefore, with one side surface 13a of the fixed abutment portion 13 abutting on one circumferential side of the key portion 9, one side surface 15a of the rotary abutment portion 15 abuts on the other side as shown in Figure 4. Therefore, the fixed abutment portion 13 and the rotary abutment portion 15 circumferentially sandwich the key portion 9, allowing the phases of the multiple core pieces 1 to be aligned. It is also possible to align the phase of the key portion 9 between the other side surfaces 13b and 15b.

[0034] The fixed abutment portion 13 and the rotating abutment portion 15 can have various shapes throughout the axial direction of the rotor core 3, such as columnar, wall-shaped, rod-shaped, etc., as long as they can abut against one side and the other side of the key portions 9 of the multiple core pieces 1 in the circumferential direction, respectively.

[0035] In this embodiment, the fixed abutment portion 13 and the rotary abutment portion 15 have a columnar cross section with a sector shape and include side surfaces 13a and 15a or other side surfaces 13b and 15b that can abut against one and the other sides of the key portion 9. The side surfaces 13a and 15a and the other side surfaces 13b and 15b are flat surfaces extending in the radial and axial directions. However, the shape of the side surfaces 13a and 15a and the other side surfaces 13b and 15b is not important as long as they can abut against one and the other sides of the key portion 9.

[0036] Two rotary abutments 15 are provided corresponding to both key portions 9 of each rotor piece 1. These rotary abutments 15 are connected to a shaft portion 23, which serves as the center of relative rotation. The shaft portion 23 may be any member capable of connecting the rotary abutments 15, but in this embodiment, it is a columnar body with a circular cross section. The shaft portion 23 may also be omitted.

[0037] Two fixed abutment portions 13 are arranged around the shaft portion 23 corresponding to both key portions 9 of each rotor piece 1. The radial inner surface 25 of the fixed abutment portion 13 is formed to have an arc-shaped cross section, allowing relative rotation of the shaft portion 23. Note that the fixed abutment portion 13 and the rotary abutment portion 15 may be provided for only one of the key portions 9.

[0038] These fixed abutment portion 13 and rotary abutment portion 15 are attached to a rotor core 3, which is a plurality of stacked core pieces 1, and are arranged within a central hole 5 of the rotor core 3. In other words, the fixed abutment portion 13 and the rotary abutment portion 15 can be easily set by being arranged and attached to the central hole 5.

[0039] With this arrangement, if the fixed abutment portions 13 and the rotary abutment portions 15 are configured to fit snugly into the central hole 5, the multiple core pieces 1 can be positioned radially. Note that it is not necessary to position the multiple core pieces 1 radially. The fixed abutment portions 13 and the rotary abutment portions 15 rotate coaxially relative to each other while positioned in the central hole 5 of the rotor core 3. Therefore, the fixed abutment portions 13 and the rotary abutment portions 15 can rotate stably relative to each other while the core pieces 1 are positioned radially.

[0040] In this embodiment, the outer peripheral surface 19 of the fixed abutment portion 13 and the outer peripheral surface 21 of the rotary abutment portion 15 have a curvature equivalent to the curvature of the center hole 5. The diameter between the outer peripheral surfaces 19 and 21 is formed to be equal to or smaller than the center hole 5 of the core piece 1. When the diameter between the outer peripheral surfaces 19 and 21 is equal to the center hole 5 of the core piece 1, radial positioning is possible. Note that when the diameter between the outer peripheral surfaces 19 and 21 is smaller than the diameter of the center hole 5 of the core piece 1, the shapes of the outer peripheral surfaces 19 and 21 can be set arbitrarily as long as the fixed abutment portion 13 and the rotary abutment portion 15 can rotate relative to each other within the center hole 5.

[0041] The fixed contact portion 13 and the rotary contact portion 15 are provided as a jig 17 that can be handled as a single unit.

[0042] Fig. 5 is a perspective view of the jig in Fig. 3, Fig. 6 is a front view of the same, Fig. 7 is a plan view of the same, Fig. 8 is an enlarged side view showing a part of the jig in Fig. 5, and Fig. 9 is an enlarged plan view showing a part of the jig in Fig. 5.

[0043] As shown in FIGS. 5 to 8, the jig 17 includes a base plate 27, the fixed contact portion 13, and the rotary contact portion 15.

[0044] The base plate 27 is a plate-like body. The planar shape of the base plate 27 can be set as appropriate, but in this embodiment, it is formed into a chamfered square in plan view. A through hole 27a is formed in the center of the base plate 27. The fixed abutment portion 13 and the rotary abutment portion 15 are supported on the base plate 27.

[0045] The fixed contact portions 13 are provided around the shaft portion 23 of the rotary contact portion 15. In this embodiment, a pair of fixed contact portions 13 are provided so as to face each other in the radial direction with the shaft portion 23 in between. These fixed contact portions 13 are each fixed to stand upright on the base plate 27.

[0046] The shaft portion 23 is concentrically fitted between the inner surfaces 25 of the fixed abutment portions 13 and is rotatable relative to the fixed abutment portions 13. A drive shaft 31 is integrally formed at the end of the shaft portion 23. The drive shaft 31 protrudes outside the base plate 27 from a through-hole 27a in the base plate 27. A drive actuator (not shown), such as an electric motor for alignment, is coupled to the drive shaft 31, and the rotational drive of the rotary abutment portions 15 is controlled.

[0047] The rotary contact portion 15 has substantially the same shape as the fixed contact portion 13, and is provided symmetrically in the radial direction around the shaft portion 23. The rotary contact portion 15 is formed integrally with the central shaft portion 23, and is set lower than the fixed contact portion 13.

[0048] The fixed contact portion 13 and the rotary contact portion 15 have inclined surfaces 13c and 15c formed on the outer periphery of the tip end thereof. The inclined surfaces 13c and 15c together form a single tapered surface 16.

[0049] 3, in the initial position where the other side surface 15b of the rotary contact portion 15 is in contact with the other side surface 13b of the fixed contact portion 13, a space 33 is provided between the fixed contact portion 13 and the rotary contact portion 15. When the fixed contact portion 13 and the rotary contact portion 15 are disposed in the central hole 5, the space 33 allows the key portion 9 to be disposed between the fixed contact portion 13 and the rotary contact portion 15 in the circumferential direction, thereby enabling relative rotation.

[0050] When positioning the core pieces 1 to align their phases, the fixed abutment portion 13 and the rotating abutment portion 15 of the jig 17 are inserted into the central hole 5 of the rotor core 3 as shown in Figure 3, and the key portion 9 is positioned circumferentially between the fixed abutment portion 13 and the rotating abutment portion 15 in the space portion 33.

[0051] At this time, the tapered surfaces 16 of the fixed contact portion 13 and the rotary contact portion 15 make it easy to insert the rotor core 3 into the central hole 5 .

[0052] By this insertion, when the outer peripheral surfaces 19 and 21 of the fixed abutment portion 13 and the rotary abutment portion 15 are fitted into the central hole 5, the core piece 1 is positioned in the radial direction.

[0053] When the drive shaft 31 is rotated by an electric motor, the rotating abutment portion 15 rotates coaxially relative to the fixed abutment portion 13 as described above, and the phases of the key portions 9 of the multiple core pieces 1 can be aligned in the circumferential direction.

[0054] 4, one side and the other side of the key portion 9 in the circumferential direction are sandwiched between the fixed abutment portion 13 and the rotary abutment portion 15 so that one side surface 13a of the fixed abutment portion 13 and one side surface 15a of the rotary abutment portion 15 abut against each other. When the drive torque of the drive actuator that drives the drive shaft 31 reaches a specified value in response to this sandwiching, the drive control of the drive actuator is stopped.

[0055] Therefore, by controlling the driving torque of the drive shaft 31, the phase of the plurality of core pieces 1 can be reliably determined between the fixed contact portion 13 and the rotary contact portion 15.

[0056] Fig. 10 is an enlarged plan view showing the periphery of the center hole of the rotor core in which a jig is installed, according to a second embodiment of the present invention. Fig. 11 is an enlarged plan view showing the periphery of the center hole of the rotor core in a positioning state, according to the second embodiment of the present invention. Note that, since the basic configuration of the second embodiment is the same as that of the first embodiment, components that are the same as or correspond to those of the first embodiment are indicated by the same reference numerals, and redundant explanations will be omitted. Note that, for ease of understanding, in Figs. 10 and 11, the fixed contact portion 13 and the rotary contact portion 15 are indicated by hatching.

[0057] The positioning method of Example 2 of the present invention is such that the outer surface 19 of the fixed abutment portion 13, which is the other of the first and second abutment portions, is positioned radially in accordance with the circumferential shape of the shaft portion 23.

[0058] Although not shown, the fixed abutment portion 13 is configured to be movable in the radial direction relative to the base plate 27. For example, the fixed abutment portion 13 may be formed separately from the base plate 27, and a guide such as a radial guide groove or guide rail for the fixed abutment portion 13 may be formed on the base plate 27.

[0059] This radial movement is set as a range in which one side surface 13a of the fixed abutment portion 13 is maintained in contact with one side of the key portion 9. In other words, it is a range in which part of the fixed abutment portion 13 and part of the key portion 9 are located on the same imaginary circle.

[0060] The outer peripheral surface 23a of the shaft portion 23 is provided with contact portions 23b. In this embodiment, a pair of contact portions 23b are provided symmetrically in the radial direction. These contact portions 23b have a larger diameter than the outer peripheral surface 23a. The diameter between the surfaces of both contact portions 23b corresponds to the diameter between the inner surfaces 25 of the fixed abutment portions 13, and is, for example, approximately the same diameter so that the surfaces of both contact portions 23b can come into contact with the inner surfaces 25 of both fixed abutment portions 13.

[0061] These contact portions 23b come into contact with an inner surface 25 of the fixed abutment portion 13 depending on the circumferential position due to the relative rotation of the rotating abutment portion 15 with respect to the fixed abutment portion 13. A gap is formed between the outer peripheral surface 23a of the shaft portion 23 and the inner surface 25 of the fixed abutment portion 13 within a range that allows the abutment to be maintained.

[0062] This gap facilitates insertion of the fixed abutment portion 13 and the rotary abutment portion 15 into the central hole 5 of the rotor core 3. When positioning the rotor pieces 1 to align their phases, the contact portion 23b of the shaft portion 23 can be pressed against the inner surface 25 of the fixed abutment portion 13 in accordance with the relative rotation of the rotary abutment portion 15 with respect to the fixed abutment portion 13. This pressing force presses the fixed abutment portion 13 radially against the inner periphery of the central hole 5 of the core piece 1, as shown in Figure 11, thereby positioning the core piece 1 radially.

[0063] In addition, the second embodiment can also achieve the same effects as the first embodiment.

[0064] REFERENCE SIGNS LIST 1 Core piece (iron core piece) 3 Rotor core (laminated iron core) 5 Center hole 9 Key portion (engagement portion) 13 Fixed contact portion (first contact portion) 13a One side surface 13b Other side surface 15 Rotational contact portion (second contact portion) 15a One side surface 15b Other side surface 17 Jig 19 Outer circumferential surface of fixed contact portion 21 Outer circumferential surface of rotational contact portion 27 Base plate 27a Through hole 33 Space portion

Claims

1. A positioning method for aligning the phase of multiple stacked core pieces having circumferential engaging portions, comprising the steps of: relatively rotating first and second abutment portions that can abut against one and the other sides, respectively, of the engaging portions in the circumferential direction; relatively moving the engaging portions in the circumferential direction between the first and second abutment portions due to the relative rotation; and abutting the first and second abutment portions against one and the other sides, respectively, of the engaging portions of each core piece in the circumferential direction, thereby sandwiching the engaging portions between the first and second abutment portions, thereby aligning the phase of the stacked multiple core pieces.

2. A positioning method according to claim 1, wherein the first and second contact parts are provided so as to be rotatable relative to one another about the same axis, and the first and second contact parts are attached to the plurality of core pieces and rotated relative to one another about the same axis to come into contact with one side and the other side of the engagement part in the circumferential direction, respectively.

3. A positioning method as claimed in claim 2, wherein the core pieces are provided with a central hole through which the engagement parts protrude radially inward, and the first and second abutment parts perform the relative rotation in a state of being fitted into the central hole.

4. A positioning method as claimed in claim 3, wherein one of the first and second abutment parts is connected to a shaft part which is the centre of the relative rotation, and the other of the first and second abutment parts is arranged around the shaft part and is movable along the radial direction within a range which enables the abutment, and the multiple iron core pieces are positioned in the radial direction by being pressed against central holes of the stacked multiple iron core pieces due to the circumferential shape of the shaft part in response to the relative rotation.

5. A jig for aligning the phase of multiple stacked core pieces each having a circumferential engagement portion and a central hole, the jig comprising: first and second abutment portions arranged to be freely rotatable relative to one another about the same axis and adapted to axially fit into the central holes of the stacked core pieces; and a space portion for arranging the engagement portion between the first and second abutment portions in the circumferential direction to allow the relative rotation of the first and second abutment portions.

6. A jig as claimed in claim 5, wherein one of the first and second contact parts is connected to a shaft part which is the centre of the relative rotation, and the other of the first and second contact parts is arranged around the shaft part so as to be capable of relative rotation.

7. A jig as claimed in claim 6, wherein the other of the first and second abutment portions is movable along the radial direction within a range that maintains the abutment, the shaft portion has a contact portion that contacts the radially inner side of the other of the first and second abutment portions in response to the relative rotation, and the contact portion presses the other of the first and second abutment portions against a central hole of the stacked multiple iron core pieces in response to the relative rotation, thereby positioning the multiple iron core pieces in the radial direction.

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