JP2024079284A - Manufacturing method of rotor core, and rotor core - Google Patents

Abstract

The present invention aims to simplify the work of reducing the amount of unbalance.
[Solution] A manufacturing method of a rotor core includes a first measuring step of individually measuring the weights of a plurality of magnets, a second measuring step of measuring the amount of unbalance in a core body provided with a plurality of magnet mounting parts and then decomposing the amount of unbalance into components in a first direction and a second direction that are perpendicular to each other, a selection step of selecting from the plurality of magnets a plurality of target magnets that can reduce at least one of a first component that is a component of the amount of unbalance in the first direction and a second component that is a component of the amount of unbalance in the second direction, and a magnet mounting step of mounting the plurality of target magnets to the plurality of magnet mounting parts so as to reduce at least one of the first component and the second component. In the selection step, the plurality of target magnets are selected so as to include at least one pair of magnets having a weight difference.
[Selected figure] Figure 10

Description

This disclosure relates to a method for manufacturing a rotor core, and to a rotor core.

Patent Document 1 discloses a method for assembling a motor rotor, which includes a step of measuring the position of the center of gravity of the iron core, and a step of obtaining a plurality of magnets having a weight difference corresponding to the amount of deviation between the rotation center of the iron core and the position of the center of gravity. This assembly method further includes a step of fixing, of the plurality of magnets, lighter magnets to magnet mounting parts in the radial direction on the side of the center of gravity position that is offset from the rotation center of the iron core, and heavy magnets to magnet mounting parts located on the point-symmetric side of the rotation center of the magnet mounting parts.

Japanese Patent Application Laid-Open No. 9-294358

This disclosure provides a rotor core manufacturing method and rotor core that are useful for simplifying the work of reducing the amount of unbalance.

A manufacturing method of a rotor core according to one aspect of the present disclosure includes a first measurement step of preparing a plurality of magnets and individually measuring the weights of the plurality of magnets, a second measurement step of preparing a core body provided with a plurality of magnet mounting parts, measuring the amount of unbalance in the core body, and then decomposing the amount of unbalance into components in a first direction and a second direction that intersect the central axis of the core body and are mutually perpendicular, a selection step of selecting, from the plurality of magnets, a plurality of target magnets that can reduce at least one of the first component, which is the component of the amount of unbalance in the first direction, and the second component, which is the component of the amount of unbalance in the second direction, based on the weight measurement result in the first measurement step and the result obtained by decomposing the amount of unbalance in the second measurement step, and a magnet mounting step of mounting the plurality of target magnets to the plurality of magnet mounting parts so as to reduce at least one of the first component and the second component. In the selection step, the plurality of target magnets are selected so as to include at least one pair of magnets having a weight difference.

A rotor core according to one aspect of the present disclosure includes a core body provided with a plurality of magnet mounting portions, and a plurality of magnets attached to the plurality of magnet mounting portions. Of the plurality of magnets, a weight difference is provided between one or more magnets located in one area defined by a first virtual line and one or more magnets located in the other area defined by the first virtual line. Of the plurality of magnets, a weight difference is provided between one or more magnets located in one area defined by a second virtual line and one or more magnets located in the other area defined by the second virtual line. The first virtual line is a line that is perpendicular to the central axis of the core body and passes through the central axis. The second virtual line is a line that is perpendicular to the central axis and the first virtual line, and passes through the central axis.

This disclosure provides a rotor core manufacturing method and rotor core that are useful for simplifying the work of reducing the amount of unbalance.

FIG. 1 is a perspective view illustrating an example of a rotor core. FIG. 2 is a vertical cross-sectional view showing a schematic diagram of an example of a rotor core. FIG. 3 is a top view illustrating an example of a rotor core. FIG. 4 is a schematic diagram showing an example of a rotor core manufacturing apparatus. 5(a) and 5(b) are flowcharts showing an example of a manufacturing method for a rotor core. FIG. 6 is a schematic diagram illustrating how magnets are stored according to weight categories. 7A and 7B are schematic diagrams for explaining measurement of the amount of unbalance. 8(a) and 8(b) are schematic diagrams illustrating a method for reducing the amount of imbalance caused by the weight difference between magnets. 9(a) and 9(b) are schematic diagrams illustrating a method for reducing the amount of imbalance caused by the weight difference between magnets. 10A and 10B are schematic diagrams illustrating a method for reducing the amount of imbalance caused by the weight difference between magnets.

One embodiment will be described below with reference to the drawings. In the description, identical elements or elements having the same functions are given the same reference numerals, and duplicate descriptions will be omitted.

[Rotor core]
First, the configuration of the rotor core will be described with reference to Figures 1 to 3. The rotor laminated core 1 shown in Figure 1 is an example of a rotor core, and is a component included in a rotor. For example, a rotor is formed by attaching a shaft to the rotor laminated core 1. A motor is formed by combining a rotor including the rotor laminated core 1 with a stator. The rotor laminated core 1 may be used in an interior permanent magnet (IPM) motor. The rotor laminated core 1 includes laminations 4, a plurality of magnets M, and a plurality of solidified resins 12.

The laminated body 4 functions as the core body. The laminated body 4 is formed in a cylindrical shape. In the center of the laminated body 4, an axial hole 4a is provided that penetrates the laminated body 4 so as to extend along the central axis Ax. The axial hole 4a extends in the stacking direction of the laminated body 4 (hereinafter simply referred to as the "stacking direction"). In other words, the stacking direction is also the extension direction of the central axis Ax of the laminated body 4. Since the laminated body 4 rotates around the central axis Ax, the central axis Ax is also the rotation axis (center of rotation). Below, the configuration of the rotor laminated core 1 will be described based on a state in which the rotor laminated core 1 is arranged so that the central axis Ax is aligned in the vertical direction.

The lamination 4 has a key 6a and a key 6b. The key 6a and the key 6b are provided on the inner peripheral surface of the shaft hole 4a. The key 6a and the key 6b are formed in a convex shape so as to protrude inward from the inner peripheral surface of the shaft hole 4a. In this disclosure, the direction approaching the central axis Ax is referred to as "inner" or "inner side", and the direction away from the central axis Ax is referred to as "outer" or "outer side". When viewed from the axial direction along which the central axis Ax extends, the key 6a and the key 6b are arranged to face each other with the central axis Ax therebetween. In this case, the center of the key 6a and the center of the key 6b are arranged at positions 180° apart from each other on the circumference around the central axis Ax. A shaft is inserted into the shaft hole 4a. The inserted shaft may be fixed to the rotor laminated core 1 by the key 6a and the key 6b.

The keys 6a and 6b also function as indicators that indicate a reference position on the circumference around the central axis Ax of the laminate 4. That is, the keys 6a and 6b identify the positions (angles) of various parts of the laminate 4 in the direction along the circumference (hereinafter referred to as the "circumferential direction"). Instead of being convex, the keys 6a and 6b may be formed concavely so as to be recessed outward on the inner circumferential surface. The laminate 4 may have one of the keys 6a and 6b instead of two keys. The laminate 4 may not have any keys, and another part of the laminate 4 (for example, a part of the through hole) may function as an indicator that indicates a reference position in the circumferential direction.

The laminate 4 is formed by stacking a number of punched members 2. The punched members 2 are plate-like members formed by punching out an electromagnetic steel sheet ES (described later) into a predetermined shape. The punched members 2 have a shape corresponding to the laminate 4. One main surface of the punched member 2 constituting the top layer of the laminate 4 corresponds to the upper end surface of the laminate 4. One main surface of the punched member 2 constituting the bottom layer of the laminate 4 corresponds to the lower end surface of the laminate 4.

The laminate 4 may be formed by so-called rolling. "Rolling" refers to stacking a plurality of punched members 2 while shifting the angles between the punched members 2 relative to each other. Rolling is performed mainly for the purpose of offsetting the thickness deviation in each of the plurality of punched members 2. The rolling angle may be set to any size.

The punched members 2 adjacent to each other in the stacking direction may be fastened to each other by a crimping portion 14 as shown in FIG. 1 or FIG. 2. These punched members 2 may be fastened to each other by various known methods instead of the crimping portion 14. For example, the multiple punched members 2 may be joined to each other using an adhesive or a resin material, or may be joined to each other by welding. Alternatively, a temporary crimp may be provided on the punched members 2, and after the multiple punched members 2 are fastened to each other via the temporary crimp to obtain the laminate 4, the temporary crimp may be removed from the laminate 4.

The laminate 4 has a plurality of magnet insertion holes H. The plurality of magnet insertion holes H function as a plurality of magnet mounting portions to which a plurality of magnets M are attached. In the example shown in FIG. 1, the plurality of magnet insertion holes H are arranged at a predetermined interval along the outer periphery of the laminate 4 (see also FIG. 3). As shown in FIG. 2, each of the plurality of magnet insertion holes H penetrates the laminate 4 so as to extend along the central axis Ax. That is, the magnet insertion holes H extend in the lamination direction. Note that FIG. 2 shows a longitudinal section of the rotor laminated core 1 cut to include the magnet insertion holes H, the crimped portion 14, and the central axis Ax.

As shown in FIG. 3, when viewed from above, the multiple magnet insertion holes H may extend along a direction intersecting the central axis Ax. When viewed from above, the shape of each of the multiple magnet insertion holes H may be rectangular. The number of multiple magnet insertion holes H shown in FIG. 1 and FIG. 3 is 16. The multiple magnet insertion holes H shown in FIG. 1 and FIG. 3 are an example, and the position, shape, and number of the magnet insertion holes H may be changed depending on the application of the motor or the required performance, etc. Some of the multiple magnet insertion holes H may be located at a different position from the other magnet insertion holes H in the radial direction of the circumference around the central axis Ax.

In the following explanation, in order to individually identify the magnet insertion holes H, the multiple magnet insertion holes H (16 magnet insertion holes H) are referred to as "magnet insertion hole H1", "magnet insertion hole H2", ... and "magnet insertion hole H16". In the above circumferential direction, the line extending from the central axis Ax to the center of the key 6a is defined as the reference position (0°), and the counterclockwise direction is defined as the positive direction (positive angle). Magnet insertion holes H1 to H16 are lined up in this order from the reference position on the circumference around the central axis Ax.

In the example shown in FIG. 3, magnet insertion holes H1-H4 are arranged in an angle range of 0° to 90°, and magnet insertion holes H5-H8 are arranged in an angle range of 90° to 180°. Magnet insertion holes H9-H12 are arranged in an angle range of 180° to 270°, and magnet insertion holes H13-H16 are arranged in an angle range of 270° to 360° (0°). The center between magnet insertion holes H1 and H16 in the circumferential direction is 0°, and the center between magnet insertion holes H4 and H5 in the circumferential direction is 90°. The center between magnet insertion holes H8 and H9 in the circumferential direction is 180°, and the center between magnet insertion holes H12 and H13 in the circumferential direction is 270°.

The multiple magnets M are attached to the multiple magnet insertion holes H. In the example shown in Figures 1 and 3, one magnet M is inserted into each of the multiple magnet insertion holes H. The magnets M are permanent magnets. The shape of the magnets M is not particularly limited, but may be a rectangular parallelepiped. The type of magnet M may be determined according to the application of the motor or the required performance, and is, for example, a sintered magnet or a bonded magnet.

Each of the multiple solidified resins 12 is a member formed by filling the magnet insertion hole H with a molten resin material (molten resin) after the magnet M is inserted, and then solidifying the molten resin. The solidified resin 12 has the function of fixing the magnet M in the magnet insertion hole H and the function of joining adjacent punched members 2 in the stacking direction (up and down direction). The magnet M is attached to the magnet insertion hole H by fixing the magnet M in the magnet insertion hole H with the solidified resin 12. Examples of the resin material forming the solidified resin 12 include thermosetting resin and thermoplastic resin. Specific examples of thermosetting resins include a resin composition containing an epoxy resin, a curing initiator, and an additive. Examples of additives include a filler, a flame retardant, or a stress reducing agent.

As with the multiple magnet insertion holes H, in order to individually identify the magnets M in the description, the multiple magnets M (16 magnets M) will be referred to as "magnet M1", "magnet M2", ... and "magnet M16". Furthermore, the magnet M attached to magnet insertion hole Hn (n is any one integer from 1 to 16) will be referred to as "magnet Mn". For example, the magnet M inserted into magnet insertion hole H1 is represented as magnet M1. Similarly, the multiple magnets M inserted into magnet insertion holes H2 to H16 are represented as magnets M2 to M16. In this case, magnets M1 to M16 are lined up in this order from the reference position on the circumference around the central axis Ax.

The laminate 4 before the magnet M is attached has a weight imbalance (hereinafter referred to as "weight imbalance"). Weight imbalance refers to a state in which the position of the center of gravity Cg of the laminate 4 is shifted with respect to the center of rotation (center axis Ax) of the laminate 4. Factors that cause the position of the center of gravity Cg to be shifted with respect to the center of rotation include uneven mass distribution in the plane of each punching member 2. Since weight imbalance occurs due to various factors, the position of the center of gravity Cg differs for each individual laminate 4. When a rotor core is formed by providing multiple magnets and solidified resin in the magnet insertion holes H with a weight imbalance in the laminate 4, the rotor core also has a weight imbalance. When a motor formed using a rotor core with such a weight imbalance is driven, abnormal vibrations, noise, etc. may occur. Hereinafter, unless otherwise specified, "weight imbalance in the laminate 4" means a weight imbalance that exists in the laminate 4 before the magnet M is attached.

In the rotor laminated core 1 of the present disclosure, the weights of the multiple magnets M (magnets M1 to M16) are determined and the multiple magnets M are attached to the multiple magnet insertion holes H (magnet insertion holes H1 to H16) so that the weight unbalance in the laminated body 4 is reduced. Reducing the weight unbalance in the laminated body 4 means that the degree of weight unbalance in the laminated body 4 with the magnets M attached is smaller than the degree of weight unbalance in the laminated body 4 before the magnets M are attached. In this case, by reducing the weight unbalance, the distance between the central axis Ax and the center of gravity of the laminated body 4 (e.g., rotor laminated core 1) after the magnets M are attached is smaller than the distance between the central axis Ax and the center of gravity Cg of the laminated body 4 before the magnets M are attached.

As shown in FIG. 3, a virtual line passing through the 0° and 180° positions in the circumferential direction and the central axis Ax is defined as a "virtual line ILx", and the direction in which the virtual line ILx extends is defined as a "direction X". A virtual line passing through the 90° and 270° positions in the circumferential direction and the central axis Ax is defined as a "virtual line ILy", and the direction in which the virtual line ILy extends is defined as a "direction Y". The virtual line ILx is perpendicular to the central axis Ax. The virtual line ILy is perpendicular to the central axis Ax and the virtual line ILx. The directions X and Y are perpendicular to each other. The directions X and Y may be along the upper end surface (or the lower end surface) of the laminate 4.

The multiple magnet insertion holes H are line-symmetric with respect to the virtual line ILx, and the multiple magnet insertion holes H are also line-symmetric with respect to the virtual line ILy. In other words, the virtual line ILx and the virtual line ILy are set so that the multiple magnet insertion holes H are line-symmetric with respect to each line. When the virtual line ILx is the first virtual line and the direction X is the first direction, the virtual line ILy corresponds to the second virtual line and the direction X corresponds to the second direction. When the virtual line ILy is the first virtual line and the direction Y is the first direction, the virtual line ILx corresponds to the second virtual line and the direction Y corresponds to the second direction.

The degree of weight imbalance can be expressed by the amount of imbalance. The amount of imbalance is, for example, an amount that correlates with the shortest distance from the center of rotation (central axis Ax) to the center of gravity Cg. The unit of the amount of imbalance may be g·cm. In the rotor laminated core 1, the weights (for example, weight categories described below) of the magnets M1 to M16 are selected so as to reduce the component of the amount of imbalance in the laminations 4 in direction X and the component of the amount of imbalance in the laminations 4 in direction Y. Then, each of the selected magnets M1 to M16 is attached to the corresponding magnet insertion hole H.

When viewed from the axial direction along which the central axis Ax extends, the rotor can be divided into two regions in the direction X, with the imaginary line ILy as the boundary. In one region divided by the imaginary line ILy (the region located on the right side of the paper in FIG. 3; hereafter referred to as the "right region"), magnets M1 to M4 and M13 to M16 are present. In the other region divided by the imaginary line ILy (the region located on the left side of the paper in FIG. 3; hereafter referred to as the "left region"), magnets M5 to M12 are present. In the rotor laminated core 1, a weight difference is provided between the magnets M1 to M4, M13 to M16 and the magnets M5 to M12 so as to reduce the component of the imbalance amount in the direction X.

When the center of gravity Cg is located in the right region, the multiple magnets M used as magnets M1 to M16 are selected so that the total weight of magnets M1 to M4, M13 to M16 is smaller than the total weight of magnets M5 to M12. When the center of gravity Cg is located in the left region, the multiple magnets M used as magnets M1 to M16 are selected so that the total weight of magnets M1 to M4, M13 to M16 is greater than the total weight of magnets M5 to M12.

When a pair of magnets that are symmetrical with respect to the imaginary line ILy is defined as "one magnet set MX," there are eight magnet sets in the example shown in FIG. 3. In the following, one magnet set MX will be written as (Ml, Mm), where l and m are each an integer between 1 and 16. The eight magnet sets MX consist of (M4, M5), (M3, M6), (M2, M7), (M1, M8), (M16, M9), (M15, M10), (M14, M11), and (M13, M12). It is sufficient that there is a weight difference in at least some of the eight magnet sets MX.

In one example, a weight difference may be provided in each of the magnet groups MX (M1, M8) and (M16, M9), while no weight difference may be provided in the other magnet groups MX. The weight difference in (M1, M8) and the weight difference in (M16, M9) may be approximately the same. In this case, the weights of magnets M1 and M16 may be approximately the same, and the weights of magnets M8 and M9 may be approximately the same, so that no weight difference occurs in direction Y due to these two magnet groups MX.

In one example, a weight difference may be provided for each of the magnet groups MX (M2, M7), (M1, M8), (M16, M9), and (M15, M10), and no weight difference may be provided for the other magnet groups MY. The weight differences for (M2, M7), (M1, M8), (M16, M9), and (M15, M10) may be approximately the same. In this case, the weights of magnets M2, M1, M16, and M15 may be approximately the same, and the weights of magnets M7, M8, M9, and M10 may be approximately the same, so that no weight difference occurs in direction Y due to these four magnet groups MX.

When viewed from the axial direction along which the central axis Ax extends, the rotor can be divided into two regions in direction Y, with imaginary line ILx as the boundary. In one region divided by imaginary line ILx (the region located on the upper side of the paper in FIG. 3; hereafter referred to as the "upper region"), magnets M1 to M8 are present. In the other region divided by imaginary line ILx (the region located on the lower side of the paper in FIG. 3; hereafter referred to as the "lower region"), magnets M9 to M16 are present. In the rotor laminated core 1, a weight difference is provided between magnets M1 to M8 and magnets M9 to M16 so as to reduce the component of the imbalance amount in direction Y.

When the center of gravity Cg is located in the upper region, the multiple magnets M used as magnets M1 to M16 are selected so that the total weight of magnets M1 to M8 is less than the total weight of magnets M9 to M16. When the center of gravity Cg is located in the lower region, the multiple magnets M used as magnets M1 to M16 are selected so that the total weight of magnets M1 to M8 is greater than the total weight of magnets M9 to M16.

When a pair of magnets that are positioned symmetrically with respect to the imaginary line ILx is defined as "one magnet group MY," there are eight magnet groups MY in the example shown in FIG. 3. The eight magnet groups MY consist of (M1, M16), (M2, M15), (M3, M14), (M4, M13), (M5, M12), (M6, M11), (M7, M10), and (M8, M9). It is sufficient that there is a weight difference between at least some of the eight magnet groups MY.

In one example, a weight difference may be provided in each of the magnet groups MY (M4, M13) and (M5, M12), and no weight difference may be provided in the other magnet groups MY. The weight difference in (M4, M13) and the weight difference in (M5, M12) may be approximately equal to each other. In this case, the weights of magnets M4 and M5 may be approximately equal to each other, and the weights of magnets M13 and M12 may be approximately equal to each other, so that no weight difference occurs in direction X due to these two magnet groups MY.

In one example, a weight difference may be provided for each of the magnet groups MY (M3, M14), (M4, M13), (M5, M12), and (M6, M11), and a weight difference may not be provided for the other magnet groups MY. The weight differences for each of (M3, M14), (M4, M13), (M5, M12), and (M6, M11) may be approximately the same. In this case, the weights of magnets M3, M4, M5, and M6 may be approximately the same, and the weights of magnets M14, M13, M12, and M11 may be approximately the same, so that no weight difference occurs in direction X due to these four magnet groups MY.

Depending on the component of the unbalance amount in each direction, the number of magnets M used to reduce the component may differ for each individual laminate 4. For example, in one laminate 4, magnets M1, M2, M15, M16 and magnets M7 to M10 may be used to reduce the component of the unbalance amount in direction X. In another laminate 4, when the component of the unbalance amount in direction X is relatively small, magnets M2, M15, M7, M10 may not be used, and magnets M1, M16, M8, M9 may be used to reduce the amount of unbalance. Similarly, in one laminate 4, magnets M3 to M6 and magnets M11 to M14 may be used to reduce the component of the unbalance amount in direction Y. In addition, in another laminate 4, if the component of the imbalance amount in direction Y is relatively small, magnets M3, M6, M11, and M14 are not used, and magnets M4, M5, M12, and M13 do not need to be used to reduce the imbalance amount.

[Rotor core manufacturing equipment]
Next, an example of a manufacturing apparatus for a rotor core will be described with reference to Fig. 4. The manufacturing apparatus 50 shown in Fig. 4 is an example of a manufacturing apparatus for a rotor core, and is an apparatus (system) that executes at least a part of the process for manufacturing the rotor laminated core 1. The manufacturing apparatus 50 includes an uncoiler 52, a sending device 56, a punching device 60, a center of gravity measuring device 62, a magnet mounting device 64, a weight measuring device 72, a magnet storage unit 74, a magnet selection device 76, and a controller 90.

Coil material 54, which is formed by winding a strip-shaped electromagnetic steel sheet ES into a coil, is attached to the uncoiler 52, and the uncoiler 52 holds the coil material 54 so that it can rotate freely. The delivery device 56 has rollers 58 and 59 that sandwich the electromagnetic steel sheet ES from above and below. The pair of rollers 58 and 59 rotate and stop based on command signals from the controller 90, and intermittently deliver the electromagnetic steel sheet ES toward the punching device 60 in sequence.

The punching device 60 operates based on an instruction signal from the controller 90. The punching device 60 has a function of forming punched members 2 by sequentially punching the electromagnetic steel sheets ES intermittently fed by the feed device 56, and a function of manufacturing the laminate 4 by sequentially stacking the punched members 2 obtained by the punching process. The laminate 4 discharged from the punching device 60 may be placed on a conveyor Cv provided to extend between the punching device 60 and the center of gravity measuring device 62. The conveyor Cv operates based on an instruction signal from the controller 90, and sends the laminate 4 to the center of gravity measuring device 62.

The center of gravity measuring device 62 measures the position of the center of gravity Cg of the stack 4 before the magnet M is attached for each stack 4 based on an instruction signal from the controller 90. The center of gravity measuring device 62 may measure the amount of imbalance in the stack 4 (e.g., an amount correlating with the shortest distance between the central axis Ax and the center of gravity Cg) and the angle of the center of gravity Cg from a reference position in the circumferential direction, and transmit information indicating these measurement results to the controller 90. The center of gravity measuring device 62 may measure the position of the center of gravity Cg of the stack 4 by various known methods. The controller 90 may store information indicating the position of the center of gravity Cg (information indicating the amount of imbalance and the angle of the center of gravity Cg) in association with information identifying each individual stack 4.

A transport device 68 is provided between the center of gravity measuring device 62 and the magnet mounting device 64. The transport device 68 transports the laminate 4 from the center of gravity measuring device 62 to the magnet mounting device 64. The magnet mounting device 64 operates based on an instruction signal from the controller 90. The magnet mounting device 64 has a function of inserting a plurality of magnets M selected by the magnet selection device 76 into a plurality of magnet insertion holes H, and a function of forming solidified resin 12 inside each of the plurality of magnet insertion holes H with the plurality of magnets M inserted therein.

The weight measuring device 72 operates based on an instruction signal from the controller 90. The weight measuring device 72 is a device that individually measures the weight of multiple magnets M. The multiple magnets M to be measured by the weight measuring device 72 are used for attachment to multiple laminates 4. The weight measuring device 72 outputs information indicating the measured weight value for each magnet M to the controller 90. The weight measuring device 72 may have a transport device 72a. The transport device 72a includes, for example, a robot hand. The transport device 72a transports the magnets M to the magnet storage unit 74 based on the operational instruction of the controller 90.

The magnet storage section 74 stores (contains) the magnets M after their weights have been measured by the weight measuring device 72, for each predetermined weight category. The magnet storage section 74 is, for example, a shelf provided with a plurality of cells corresponding to a plurality of weight categories. In one example, a plurality of weight categories are set according to the difference in weight of the magnets M within the tolerance. The weight categories may be set in units of 0.01 g to 0.1 g. It is assumed that the weight of the magnet M, including the tolerance, is 10±0.4 (g) and the weight categories are set in units of 0.1 g. In this case, eight weight categories are set. The smallest weight category includes magnets M that are 9.6 g or more and less than 9.7 g. The heaviest weight category includes magnets M that are 10.3 g or more and less than 10.4 g.

The magnets M may be separated (sorted) into weight categories by transporting the magnets M to one of a number of cells in the magnet storage unit 74 according to the measured weight of the magnets M. The transport device 72a of the weight measuring device 72 transports (places) the magnets M into a cell of the magnet storage unit 74 that corresponds to the measured weight of the magnets M, among the number of cells in the magnet storage unit 74, based on the operational instructions of the controller 90. The magnet storage unit 74 may transmit information indicating the number of magnets M stored in each of the multiple weight categories to the controller 90 at a predetermined cycle.

The magnet selection device 76 operates based on operational instructions from the controller 90. The magnet selection device 76 may include a robot hand. For example, the magnet selection device 76 transports the multiple magnets M used in each stack 4 from the magnet storage unit 74 to the magnet mounting device 64. Hereinafter, the multiple magnets M to be mounted on each stack 4 are referred to as the "multiple magnets M to be mounted." When the multiple magnets M to be mounted are mounted on the stack 4, the multiple magnets M constitute the magnets M1 to M16.

The controller 90 is a computer that controls the uncoiler 52, the sending device 56, the punching device 60, the center of gravity measuring device 62, the magnet mounting device 64, the weight measuring device 72, and the magnet selection device 76. The controller 90 is configured to generate instruction signals for operating various controlled devices, for example, based on a program recorded on a recording medium or operation input from an operator. The controller 90 is configured to transmit the instruction signals to each of the various controlled devices. The controller 90 may include a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), etc.

The controller 90 controls the weight measuring device 72 to measure the magnets M individually, and controls the center of gravity measuring device 62 to measure the amount of unbalance in the stack 4 and resolves the amount of unbalance into components in the X and Y directions. The controller 90 further selects, from the magnets M, the magnet selection device 76 to select the magnets M to be attached that can reduce the components of the amount of unbalance in at least one of the X and Y directions (e.g., both) based on the measurement results of the weight of the magnets M and the results obtained by resolving the amount of unbalance. The controller 90 attaches the magnets M to be attached to the magnet insertion holes H by the magnet attachment device 64 so as to reduce the amount of unbalance in at least one of the X and Y directions (e.g., both).

[Method of manufacturing rotor core]
Next, an example of a manufacturing method for a rotor core will be described with reference to Figures 5 to 10. The manufacturing method for a rotor core includes at least a first measuring step, a second measuring step, a selection step, and a magnet mounting step. In the manufacturing method for a rotor core, a series of steps including the second measuring step, the selection step, and the magnet mounting step may be repeated during a period overlapping with at least a portion of the period during which the first measuring step is performed. By repeating the series of steps, a plurality of rotor laminated cores 1 may be manufactured in sequence.

The first measurement step is a step of preparing a plurality of magnets M and individually measuring the weight of the plurality of magnets M. The second measurement step is a step of preparing a laminate 4 having a plurality of magnet insertion holes H, measuring the amount of unbalance in the laminate 4, and then decomposing the amount of unbalance into components in the X direction and the Y direction. The selection step is a step of selecting, from the plurality of magnets M, a plurality of magnets M to be attached (a plurality of magnets to be attached) that can reduce at least one of the components of the unbalance amount in the X direction and the components of the unbalance amount in the Y direction, based on the weight measurement result in the first measurement step and the result obtained by decomposing the amount of unbalance in the second measurement step. In the selection step, the plurality of magnets M to be attached are selected so as to include at least one pair of magnets M having a weight difference (one or more pairs of magnets M having a weight difference).

The magnet mounting process is a process of mounting a plurality of magnets M to be mounted into a plurality of magnet insertion holes H so as to reduce at least one of the component of the unbalance amount in the X direction (hereinafter simply referred to as the "X component") and the component of the unbalance amount in the Y direction (hereinafter simply referred to as the "Y component"). Note that when the X component is the first component, the Y component corresponds to the second component, and when the Y component is the first component, the X component corresponds to the second component.

Figure 5 (a) is a flow chart showing an example of the first measurement process. In the first measurement process, step S11 is executed first. In step S11, for example, the weight of one magnet M is measured by the weight measuring device 72, and the controller 90 acquires the measurement result of the weight of the magnet M. Next, step S12 is executed. In step S12, for example, the controller 90 determines a corresponding category among a plurality of weight categories according to the weight measurement result in step S11. Then, the controller 90 controls the transport device 72a of the weight measuring device 72 so that the target magnet M is transported to the cell corresponding to the weight category determined in the magnet storage unit 74.

After step S12 is performed, or in parallel with step S12, step S11 is performed for another magnet M. Then, steps S11 and S12 are repeatedly performed. By repeatedly performing steps S11 and S12, multiple magnets M are divided (classified) into weight categories according to the weight measurement results in the first measurement process. Note that FIG. 6 uses a graph to show a state in which multiple magnets M are stored divided into eight weight categories. If the weight categories are set within the tolerance range, a bias in the number of magnets stored may occur, as shown in FIG. 6.

Figure 5(b) is a flow chart showing an example of a series of steps including the second measurement step, the selection step, and the magnet attachment step. Figure 5(b) shows the series of steps performed in the process of manufacturing one rotor laminated core 1.

In the above series of steps, step S21 is executed first. In step S21, for example, the controller 90 acquires information indicating the number of magnets M stored for each weight category in the magnet storage unit 74 (hereinafter referred to as "storage information"). The storage information acquired by the controller 90 may be information indicating the number of magnets M stored at the time when step S21 is executed (the current time). In this way, the above series of steps may include an information acquisition step of acquiring the storage information.

Next, step S22 is executed. In step S22, for example, the controller 90 controls the center of gravity measuring device 62 to obtain information indicating the position of the center of gravity Cg in the laminate 4 from the center of gravity measuring device 62. As shown in FIG. 7(a), the controller 90 may obtain from the center of gravity measuring device 62 information indicating the amount of unbalance UA that correlates with the shortest distance between the central axis Ax and the center of gravity Cg, and information indicating the angle θ of the center of gravity Cg in the circumferential direction.

Next, step S23 is executed. In step S23, for example, the controller 90 uses the angle θ obtained in step S22 to calculate the component in the direction X (the X component) and the component in the direction Y (the Y component) of the unbalance amount UA. In FIG. 7B, the X component of the unbalance amount UA is indicated by "UAx" and the Y component is indicated by "UAy". The controller 90 may set the sign of the X component to plus when the center of gravity Cg is located in the right region, and may set the sign of the X component to minus when the center of gravity Cg is located in the left region. The controller 90 may set the sign of the Y component to plus when the center of gravity Cg is located in the upper region, and may set the sign of the Y component to minus when the center of gravity Cg is located in the lower region. The first measurement process is executed by executing steps S22 and S23.

Next, step S24 is executed. In step S24, for example, the controller 90 selects the multiple magnets M to be attached from the multiple magnets M stored (contained) in the magnet storage unit 74 based on the magnitude and sign of the X component and the magnitude and sign of the Y component obtained in step S23. When the multiple magnets M are divided into weight categories in the magnet storage unit 74, selecting the multiple magnets M to be attached means determining the weight category of each of the multiple magnets M that will become the multiple magnets M to be attached (magnets M1 to M16). In other words, selecting the multiple magnets M to be attached means determining which weight category the magnet M belongs to for each of the magnet insertion holes H1 to H16. The above selection process is performed by executing step S24.

Next, step S25 is executed. In step S25, for example, the controller 90 uses the magnet mounting device 64 to mount the multiple magnets M to be mounted, selected in step S24, into the multiple magnet insertion holes H so as to reduce the first and second components. In one example, the controller 90 controls the magnet selection device 76 and the magnet mounting device 64 to mount the multiple magnets M, whose weight class and magnet insertion holes H to be mounted have been determined in step S24, into the multiple magnet insertion holes H according to the determination result in step S24.

Through the above steps S21 to S25, one rotor laminated core 1 is manufactured. In the process of manufacturing the rotor laminated core 1, the above steps S21 to S25 may be repeated to manufacture another subsequent rotor laminated core 1. Below, a specific example of a method for reducing (decreasing) the amount of unbalance by using the weight difference of magnets is described.

In step S24, the controller 90 determines which magnet groups among the magnets M1 to M16 will have a weight difference, depending on the calculation results of the X and Y components obtained in step S23. Hereinafter, the magnet groups with a weight difference will be referred to as "balancing magnet groups", and the magnet groups without a weight difference will be referred to as "non-balancing magnet groups". Figures 8(a), 8(b), 9(a), and 9(b) show examples of various patterns for reducing the component of the unbalance amount in the Y direction. In Figures 8(a), 8(b), 9(a), and 9(b), the magnitude of the Y component (the level of unbalance amount) increases in this order, and the center of gravity Cg is located in the upper region. In these figures, the weight of the selected magnet M is represented diagrammatically by the size of the hatched circle.

In the examples shown in Figures 8(a), 8(b), 9(a), and 9(b), at least a portion of magnets M3 to M6 and at least a portion of magnets M11 to M14 are used to reduce the Y component. An example of the selection results of multiple magnets M (weight categories of magnets M3 to M6 and M11 to M14) to be attached in relation to the reduction of the Y component is summarized in Table 1 below. In Table 1, Figure 8(a) corresponds to pattern I, Figure 8(b) corresponds to pattern II, Figure 9(a) corresponds to pattern III, and Figure 9(b) corresponds to pattern IV.

In pattern I shown in FIG. 8(a), the magnitude of the Y component is relatively small. Therefore, of magnets M3 to M6, M11 to M14, (M4, M13) and (M5, M12) are used as the magnet group MY for balancing. In this case, (M3, M14) and (M6, M11) are the magnet group MY for non-balancing. In each of the magnet groups MY (M4, M13) and (M5, M12), the difference in weight category of a pair of magnets M is 1. In FIG. 6, the selection at "unbalance level 1" corresponds to the above pattern I. In each of the magnet groups MY (M4, M13) and (M5, M12), the weight category of each magnet M is determined to be category 4 or category 5, where the number of magnets M stored in the storage information is equal to or greater than a predetermined number Th. For the magnet sets MY of (M3, M14) and (M6, M11), the weight category of each magnet M is determined to be category 5, which is the weight category with the largest number of magnets M stored in the storage information.

In pattern II shown in FIG. 8(b), the magnitude of the Y component is larger than that in pattern I. As in pattern I, (M4, M13) and (M5, M12) are used as magnet groups MY for balancing. Unlike pattern I, the difference in weight category between a pair of magnets M is 2 in each of the magnet groups MY (M4, M13) and (M5, M12). In FIG. 6, the selection at "unbalance level 2" corresponds to the above pattern II. In each of the magnet groups MY (M4, M13) and (M5, M12), the weight category of each magnet M is determined to be category 4 or category 6, where the number of magnets M stored in the storage information is equal to or greater than a predetermined number Th. As in pattern I, the weight category of each magnet M is determined to be category 5 in the magnet groups MY (M3, M14) and (M6, M11).

In pattern III shown in FIG. 9(a), the magnitude of the Y component is larger than in pattern II. Therefore, unlike patterns I and II, (M3, M14), (M4, M13), (M5, M12), and (M6, M11) of magnets M3 to M6, M11 to 14 are used as magnet sets MY for balancing. In magnet sets MY for (M3, M14), (M4, M13), (M5, M12), and (M6, M11), the difference in weight class between a pair of magnets M is 1. Even if the difference in weight class between a pair of magnets M is 1, the number of magnet sets for balancing is large, so the degree to which the Y component can be reduced in pattern III is greater than that in pattern II. In FIG. 6, the selection at "unbalance level 3" corresponds to the above pattern III. For magnet sets MY consisting of (M3, M14), (M4, M13), (M5, M12), and (M6, M11), the weight classification of each magnet M is determined to be category 4 or category 5, where the number of magnets M stored is equal to or greater than a predetermined number Th.

In pattern IV shown in FIG. 9(b), the magnitude of the Y component is larger than that in pattern III. As in pattern III, (M3, M14), (M4, M13), (M5, M12), and (M6, M11) are used as magnet groups MY for balancing. Unlike pattern III, the difference in weight category between a pair of magnets M is 2 in each of the magnet groups MY of (M3, M14), (M4, M13), (M5, M12), and (M6, M11). In FIG. 6, the selection at "unbalance level 4" corresponds to the above pattern IV. In the magnet groups MY of (M3, M14), (M4, M13), (M5, M12), and (M6, M11), the weight category of each magnet M is determined to be category 4 and category 6, where the number of magnets M stored is equal to or greater than the predetermined number Th.

When reducing the component of the imbalance amount in the X direction (X component), various patterns similar to those for reducing the Y component may be employed. At least a portion of the magnets M1, M2, M15, and M16 and at least a portion of the magnets M7 to M10 may be used to reduce the X component. An example of the selection results of multiple magnets M (weight categories of magnets M1, M2, M7 to M10, M15, and M16) to be attached in relation to reducing the X component when the center of gravity Cg is located in the right region is summarized in Table 2 below. Note that schematic diagrams similar to those in Figure 8(a) and the like are omitted.

For the reduction of the X component, as with the reduction of the Y component, the weight classification for each of the magnets M1, M2, M7 to M10, M15, and M16 may be determined based on the storage information. In the examples shown in Tables 1 and 2, the reduction of the X component and the Y component are performed independently of each other. Therefore, depending on the position of the center of gravity Cg, the reduction of the X component and the Y component may result in the same pattern selection, or may result in different patterns selection. FIG. 10(a) shows a schematic diagram of the selection result (weight classification selection result of the magnets M1 to M16) of the multiple magnets M to be attached when the reduction of the X component is pattern III and the reduction of the Y component is pattern I. In the examples shown in Tables 1 and 2, the magnets M in the area surrounded by the dashed lines marked with "y1" and "y2" contribute to the reduction of the Y component. In addition, the magnets M in the area surrounded by the dashed lines marked with "x1" and "x2" contribute to the reduction of the X component.

As described above, in step S24, the controller 90 may select (determine) one or more magnet sets MX capable of reducing the X component based on the calculation result of the X component obtained in step S23. Each of the one or more selected magnet sets MX is composed of a pair of magnets M having a weight difference. Selecting (determining) one or more magnet sets MX capable of reducing the X component may include determining which magnet set MX of the eight magnet sets MX included in magnets M1 to M16 is to be used for reduction, and the weight difference in the magnet sets MX.

In addition, in step S24, the controller 90 may select (determine) one or more magnet sets MY (one or more other magnet sets) capable of reducing the Y component based on the calculation result of the Y component obtained in step S24. Each of the one or more selected magnet sets MY consists of a pair of magnets M having a weight difference. Selecting (determining) one or more magnet sets MY capable of reducing the Y component may include determining which magnet set MY out of the eight magnet sets MY included in magnets M1 to M16 is to be used for reduction, and the weight difference in the magnet set MY.

When multiple magnets M are divided into weight categories in the magnet storage section 74, the magnets M having a weight difference between them means that the weight category to which one magnet M belongs is different from the weight category to which another magnet M belongs. Furthermore, the weight differences between the magnets M being approximately the same means that the weight categories to which these two magnets M belong are the same.

In step S24, the controller 90 may select the multiple magnets M to be attached so that the multiple magnets M include the one or more magnet sets MX that reduce the X component and the one or more magnet sets MY that reduce the Y component. The multiple magnets M to be attached may include multiple magnets M (multiple standard magnets) that do not contribute to reducing the amount of imbalance in the laminate 4. For example, in pattern I shown in Table 1 and FIG. 8(a), magnets M3, M6, M11, and M14 do not contribute to reducing the Y component (X component and Y component).

In step S24, the controller 90 may determine the number of the one or more magnet groups MX for reducing the X component and the magnet insertion holes H for mounting the one or more magnet groups MX according to the magnitude of the X component. The controller 90 may determine the number of the one or more magnet groups MY for reducing the Y component and the magnet insertion holes H for mounting the one or more magnet groups MY according to the magnitude of the Y component. In this case, determining which magnet group MX (magnet group MY) is used to reduce the X component (Y component) of the unbalance amount corresponds to determining the number of magnet groups and the magnet insertion holes H for mounting the magnet groups. In step S24, the controller 90 may determine the difference in weight class between a pair of magnets M in each of the one or more magnet groups MX for reducing the X component according to the magnitude of the X component. The controller 90 may determine the difference in weight class between a pair of magnets M in each of the one or more magnet groups MY for reducing the Y component according to the magnitude of the Y component.

In step S24, the controller 90 may determine the number of one or more magnet sets MX for reducing the X component, the magnet insertion holes H for mounting the one or more magnet sets MX, and the weight class difference between a pair of magnets M in each of the one or more magnet sets MX, depending on the magnitude of the X component. In the example shown in Table 2, the controller 90 may select one of the above patterns I to IV depending on the magnitude (level) of the X component. Note that, if the weight class difference is the same in the one pattern selected, a class different from the classes shown in Table 2 may be selected.

In step S24, the controller 90 may determine the number of the one or more magnet sets MY for reducing the Y component, the magnet insertion holes H for mounting the one or more other magnet sets MY, and the weight class difference between a pair of magnets M in each of the one or more magnet sets MY, depending on the magnitude of the Y component. In the example shown in Table 1, the controller 90 may select one of the above patterns I to IV depending on the magnitude (level) of the Y component. Note that, if the weight class difference is the same in the one pattern selected, a class different from the classes shown in Table 1 may be selected.

In step S24, the controller 90 may select multiple magnets M to be attached based on the storage information obtained in step S21. In one example, the controller 90 selects magnets M included in the magnet set for which a weight difference is to be provided from a weight category in which the number of stored magnets M in the storage information obtained in step S21 is equal to or greater than a predetermined number Th. That is, the controller 90 selects magnets M constituting the one or more magnet sets MX for reducing the X component and the one or more magnet sets MY for reducing the Y component from a plurality of weight categories in which the number of stored magnets M is equal to or greater than a predetermined number Th. The predetermined number Th may be set in advance by an operator or the like, or may be set based on the storage information after the storage information is obtained in step S21 and before step S24 is executed.

In step S24, if the multiple magnets M to be attached include multiple magnets M that do not contribute to reducing the amount of unbalance, the controller 90 may select the multiple magnets M as follows. The controller 90 selects multiple magnets M that do not contribute to reducing the amount of unbalance from the weight category with the largest number of magnets M stored in the storage information acquired in step S21. The presence or absence of multiple magnets M that do not contribute to reducing the amount of unbalance and their number are determined for each individual piece of the laminate 4 by the selection result of the one or more magnet sets MX that reduce the X component and the one or more magnet sets MY that reduce the Y component.

In step S25, a plurality of magnets M to be mounted, including the one or more magnet sets MX that reduce the X component and the one or more magnet sets MY that reduce the Y component, may be mounted in a plurality of magnet insertion holes H. When the above series of steps are repeated, in the selection step, the maximum number of one or more magnet sets MX for reducing the X component and the maximum number of one or more magnet sets MY for reducing the Y component may be the same. In the examples shown in Tables 1 and 2, a maximum of four magnet sets MX are used for reducing the X component, and a maximum of four magnet sets MY are used for reducing the Y component.

[Modification]
The disclosure in this specification should be considered to be illustrative and not restrictive in all respects. Various omissions, substitutions, or modifications may be made to the above examples without departing from the scope and spirit of the claims.

In the above-mentioned example of the manufacturing method of the rotor laminated core 1, in the selection process, a plurality of magnets M to be attached that can reduce both the X component and the Y component are selected. In the selection process, a plurality of magnets M to be attached that can reduce either the X component or the Y component may be selected based on the calculation results of the X component and the Y component. The controller 90 may select a plurality of magnets M to be attached that can reduce only the X component when the ratio of the X component to the Y component is greater than a predetermined level. The controller 90 may select a plurality of magnets M to be attached that can reduce only the Y component when the ratio of the Y component to the X component is greater than a predetermined level. FIG. 10(b) shows an example in which there is no weight difference in the magnets M in the Y direction, and there is a weight difference in the magnets M in the X direction.

In the selection of the multiple magnets M to be attached that can reduce either the X component or the Y component, the difference in weight class between the pair of magnets M that can reduce the X component may be determined according to the magnitude of the X component when the X component is reduced. In addition, in this selection, the difference in weight class between the pair of magnets M that can reduce the Y component may be determined according to the magnitude of the Y component when the Y component is reduced. In the selection of the multiple magnets M to be attached based on the storage information, when the X component is reduced, a pair of magnets M that can reduce the X component may be selected from a weight class in which the number of magnets M stored in the storage information is equal to or greater than a predetermined number. In addition, in the above selection based on the storage information, when the Y component is reduced, a pair of magnets M that can reduce the Y component may be selected from a weight class in which the number of magnets M stored in the storage information is equal to or greater than a predetermined number.

When manufacturing multiple rotor laminated cores 1, some of the magnets M among the magnets M1 to M16 may be used in one rotor laminated core 1 to reduce the X component, and in another rotor laminated core 1 to reduce the Y component. For example, in one rotor laminated core 1, the magnet set MX of (M2, M7) and (M15, M10) may have a weight difference to reduce the X component. And in another rotor laminated core 1, the magnet set MY of (M2, M15) and (M7, M10) may have a weight difference to reduce the Y component.

In the above example, the number of one or more magnet sets MX for reducing the X component varies depending on the magnitude of the X component. Alternatively, the difference in weight classes may be determined according to the magnitude of the X component, without changing the number of one or more magnet sets MX for reducing the X component, so that the difference in weight classes increases as the magnitude of the X component increases. Similarly, the difference in weight classes may be determined according to the magnitude of the Y component, without changing the number of one or more magnet sets MY for reducing the Y component, so that the difference in weight classes increases as the magnitude of the Y component increases.

In the above example, the difference in weight class differs depending on the magnitude of the X component. Alternatively, the multiple magnets M to be attached may be selected depending on the magnitude of the X component, without changing the difference in weight class, such that the number of one or more magnet sets MX for reducing the X component increases as the magnitude of the X component increases. Similarly, the multiple magnets M to be attached may be selected depending on the magnitude of the Y component, without changing the difference in weight class, such that the number of one or more magnet sets MY for reducing the Y component increases as the magnitude of the Y component increases.

The various patterns shown in Tables 1 and 2 are examples, and a pattern in which the difference in weight classes is 3 or more may be set in a magnet set for reducing any of the components. In the manufacturing method of the rotor laminated core 1, multiple magnets M manufactured to have different weights may be prepared, instead of being differentiated by weight classes within the weight tolerance. A pair of magnets M constituting a magnet set for reducing each component may be selected based on the measured weight instead of the difference between weight classes.

In the second measurement step, in addition to the direction X and the direction Y, the amount of unbalance may be resolved in one or more other directions intersecting these directions. One or more magnet pairs that reduce the components of the amount of unbalance may be selected in each of the one or more other directions. In the above example, the imaginary line ILx is set to pass through the key 6a, but the imaginary line ILx may be shifted by a predetermined angle from the indicator parts of the keys 6a, 6b, etc. in the circumferential direction. In the above example, the X component or the Y component is reduced by the weight difference between a pair of magnets M attached to a pair of magnet insertion holes H that are in a line-symmetrical position with respect to the imaginary line. Alternatively, the X component or the Y component may be reduced by the weight difference between a pair of magnets M attached to a pair of magnet insertion holes H that are not in a line-symmetrical position with respect to the imaginary line. The direction in which the amount of unbalance is resolved (for example, the direction X and the direction Y) may be set to intersect the central axis Ax without being perpendicular to the central axis Ax. Two or more directions for resolving the amount of imbalance and the virtual line ILx and the virtual line ILy may be set to intersect with each other in a plane that intersects (e.g., perpendicular to) the central axis Ax.

In the above example, the laminate 4 formed by stacking multiple punched members 2 functions as the core body to which the magnet M is attached, but the core body may be composed of something other than the laminate. For example, the core body may be formed by compression molding ferromagnetic powder, or injection molding a resin material containing ferromagnetic powder. In the above example, the multiple magnet insertion holes H function as multiple magnet mounting parts, but at least some of the multiple magnet mounting parts may be grooves provided on the outer circumferential surface of the core body. The magnets may be manually attached in the magnet mounting device 64 by an operator. At least some of the process of transporting the magnet M or the laminate 4 may be manually performed.

At least some of the matters described in one of the various examples described above may be applied to the other examples.

[Summary of the Disclosure]
The present disclosure includes the following methods or configurations (1) to (10).

(1) A first measurement step of preparing a plurality of magnets M and measuring the weights of the plurality of magnets M individually; a second measurement step of preparing a laminate 4 (core body) having a plurality of magnet insertion holes H (a plurality of magnet mounting portions), measuring the amount of unbalance in the laminate 4, and then decomposing the amount of unbalance into components in a direction X (a first direction) and a direction Y (a second direction) that intersect with the central axis Ax of the laminate 4 and intersect with each other; and a first measurement step of determining the weight of the plurality of magnets M based on the weight measurement results in the first measurement step and the results obtained by decomposing the amount of unbalance in the second measurement step. the manufacturing method of a rotor laminated core 1 (rotor core) including a selection process for selecting a plurality of magnets M to be mounted (a plurality of magnets to be mounted) capable of reducing at least one of an X component which is a component in a direction X of the unbalance amount and a Y component which is a component in a direction Y of the unbalance amount, and a magnet mounting process for mounting the plurality of magnets M to be mounted into a plurality of magnet insertion holes H so as to reduce at least one of the X component and the Y component, wherein in the selection process, the plurality of magnets M to be mounted are selected so as to include at least one pair of magnets M having a weight difference.
It is conceivable to reduce the amount of unbalance in the core body by utilizing the weight difference of the magnets attached to the core body such as the laminate 4. For example, a method is conceivable in which the amount of unbalance is reduced in a direction along a line connecting the central axis of the core body and the center of gravity by utilizing the weight difference of the magnets. In this method, there may be cases where there is no magnet attachment part on the line to which magnets having a weight difference can be attached, which may complicate the selection of magnets to reduce the amount of unbalance. In contrast, in the above manufacturing method, the amount of unbalance is resolved in two mutually intersecting directions, and the component of the amount of unbalance is reduced in at least one direction. In this case, the above two directions can be set according to the direction in which the magnet attachment parts to which magnets having a weight difference can be attached are arranged, regardless of the position of the center of gravity. This makes it easy to select multiple magnets M to be attached, including magnets to reduce the amount of unbalance. Therefore, the above manufacturing method is useful for simplifying the work of reducing the amount of unbalance.

(2) The manufacturing method described in (1) above, wherein the selection step includes selecting one or more magnet sets MX capable of reducing the X-component based on a result obtained by decomposing the amount of unbalance in the second measurement step, and selecting one or more magnet sets MY (another magnet set) capable of reducing the Y-component based on a result obtained by decomposing the amount of unbalance in the second measurement step, wherein each of the one or more magnet sets MX is made of a pair of magnets M having a weight difference, and each of the one or more magnet sets MY is made of a pair of magnets having a weight difference, and in the selection step, a plurality of magnets M to be attached are selected so as to include the one or more magnet sets MX and the one or more magnet sets MY, and in the magnet attaching step, the plurality of magnets M to be attached are attached to a plurality of magnet insertion holes H so as to reduce the X-component and the Y-component.
In the above-mentioned method, if there is no magnet mounting portion on the line connecting the central axis and the center of gravity to which magnets with weight differences can be attached, the amount of unbalance may not be reduced accurately. In contrast, in this method, the amount of unbalance is resolved into, for example, the X component and the Y component, and the components of the unbalance amount can be reduced in each direction, making it possible to reduce the amount of unbalance with high accuracy.

(3) The manufacturing method described in (2) above, wherein the selection process includes determining the number of the one or more magnet groups MX and magnet insertion holes H (magnet mounting portions) for mounting the magnets M included in the one or more magnet groups MX according to the magnitude of the X component, and determining the number of the one or more magnet groups MY and magnet insertion holes H (magnet mounting portions) for mounting the magnets M included in the one or more magnet groups MY according to the magnitude of the Y component.
In this case, the greater the degree of imbalance, the more the number of magnets M that provide a weight difference can be increased, so that the position of the center of gravity after the magnets M are attached can be made closer to the central axis Ax with higher accuracy.

(4) The manufacturing method described in (2) or (3) above, in which a series of steps including a second measurement step, a selection step, and a magnet mounting step are repeated, and the maximum number of the one or more magnet groups MX selected in the selection step and the maximum number of the one or more magnet groups MY selected in the selection step are the same as each other.
The position of the center of gravity Cg may vary for each individual core body such as the laminated body 4. In this method, since the maximum number of magnets M required to reduce the X-component and the Y-component are the same, it is possible to adjust the position of the center of gravity in a well-balanced manner in two directions.

(5) A manufacturing method according to any one of (1) to (4) above, wherein the first measuring step includes dividing the multiple magnets M into weight categories according to the weight measurement results, and the selection step determines, in the case of reducing the X component, a difference in weight category between a pair of magnets M capable of reducing the X component among the multiple magnets M to be attached, according to the magnitude of the X component, and, in the case of reducing the Y component, determines, in the case of reducing the Y component, a difference in weight category between a pair of magnets M capable of reducing the Y component among the multiple magnets M to be attached, according to the magnitude of the Y component.
In this case, the greater the degree of imbalance, the greater the difference in weight classes can be made. When the difference in weight classes is large, the weight difference between the magnets M for adjusting the position of the center of gravity is large, so it is possible to more accurately approximate the position of the center of gravity after the magnets M are attached to the central axis Ax.

(6) A manufacturing method described in (5) above, further including an information acquisition step of acquiring storage information indicating the number of magnets M stored for each weight category before executing the selection step, and the selection step includes selecting multiple magnets M to be attached based on the storage information.
In this case, even if there is a difference in the number of magnets M stored between weight categories, it is possible to select (consume) the magnets M to be attached to the core body such as the laminate 4 so as to reduce the difference.

(7) The manufacturing method described in (6) above, in which, in selecting the multiple magnets M to be attached based on the storage information, when the X component is reduced, a pair of magnets M capable of reducing the X component of the multiple magnets M to be attached is selected from a weight category in which the number of stored magnets M in the storage information is a predetermined number or more, and when the Y component is reduced, a pair of magnets M capable of reducing the Y component of the multiple magnets M to be attached is selected from a weight category in which the number of stored magnets M in the storage information is a predetermined number or more.
In this case, in order to reduce the amount of imbalance, magnets M are used (consumed) preferentially in the weight category in which a relatively large number of magnets M are stored. Therefore, it is possible to reduce the difference in the number of magnets M stored between the weight categories.

(8) A manufacturing method described in any one of (5) to (7) above, wherein selecting a plurality of magnets M to be installed based on the storage information includes, when the plurality of magnets M to be installed include a plurality of standard magnets that do not contribute to reducing the amount of imbalance, selecting the plurality of standard magnets from the weight category in which the largest number of magnets M are stored in the storage information.
Depending on the position of the center of gravity Cg in the core body such as the laminated body 4, it may not be necessary to utilize all of the magnets M used in the core body to reduce the amount of unbalance. In this method, magnets M that do not contribute to reducing the amount of unbalance are used (consumed) starting from the weight category with the largest number of magnets stored. This makes it possible to reduce the difference in the number of magnets M stored between weight categories.

(9) The manufacturing method according to any one of (1) to (8) above, wherein the direction X and the direction Y are set based on an index portion that represents a reference position on a circumference around the central axis Ax of the laminate 4.
In this case, it is easy to specify the direction X and the direction Y using the indicator portion, which is further useful for simplifying the work of reducing the amount of unbalance.

(10) A rotor laminated core 1 (rotor core) comprising a laminate 4 (core body) having a plurality of magnet insertion holes H (a plurality of magnet mounting portions) and a plurality of magnets M attached to the plurality of magnet insertion holes H, wherein a weight difference is provided between one or more magnets M located in one area defined by a virtual line ILx and one or more magnets M located in the other area defined by the virtual line ILx, and a weight difference is provided between one or more magnets M located in one area defined by a virtual line ILy and one or more magnets M located in the other area defined by the virtual line ILy, wherein the virtual line ILx is a line perpendicular to a central axis Ax of the laminate 4 and passes through the central axis Ax, and the virtual line ILy is a line intersecting the virtual line ILx in a plane perpendicular to the central axis Ax and passing through the central axis Ax.
When manufacturing this rotor laminated core 1, similarly to the above manufacturing method, it is easy to select a plurality of magnets M to be attached, including magnets for reducing the amount of unbalance, and therefore is useful for simplifying the work of reducing the amount of unbalance.

1... rotor laminated core, 4... laminated body, 6a, 6b... key, H, H1 to H16... magnet insertion holes, M, M1 to M16... magnets, MX, MY... magnet set, Ax... central axis, Cg... center of gravity, ILx, ILy... imaginary line.

Claims (10)

a first measuring step of preparing a plurality of magnets and measuring the weights of the plurality of magnets individually;
a second measurement step of preparing a core body provided with a plurality of magnet mounting portions, measuring an amount of unbalance in the core body, and then decomposing the amount of unbalance into components in a first direction and a second direction that intersect with a central axis of the core body and intersect with each other;
a selection process for selecting, from the plurality of magnets, a plurality of target magnets that can reduce at least one of a first component, which is a component of the amount of unbalance in the first direction, and a second component, which is a component of the amount of unbalance in the second direction, based on the weight measurement result in the first measurement process and the result obtained by resolving the amount of unbalance in the second measurement process;
a magnet mounting step of mounting the plurality of target magnets to the plurality of magnet mounting portions so as to reduce at least one of the first component and the second component,
A manufacturing method of a rotor core, wherein in the selecting step, the plurality of target magnets are selected so as to include at least one pair of magnets having a weight difference. The selection step includes:
selecting one or more magnet pairs capable of reducing the first component based on a result obtained by resolving the amount of unbalance in the second measurement step;
selecting one or more other magnet sets capable of reducing the second component based on a result obtained by resolving the amount of unbalance in the second measuring step;
Each of the one or more magnet sets comprises a pair of magnets having a weight difference;
each of the one or more other magnet sets comprises a pair of magnets having a weight difference;
In the selection step, the plurality of target magnets are selected so as to include the one or more magnet sets and the one or more other magnet sets;
The manufacturing method according to claim 1 , wherein in the magnet mounting step, the plurality of target magnets are mounted to the plurality of magnet mounting portions so as to reduce the first component and the second component. The selection step includes:
determining a number of the one or more magnet sets and magnet mounting portions for mounting magnets included in the one or more magnet sets according to a magnitude of the first component;
and determining a number of the one or more other magnet sets and magnet mounting portions for mounting magnets included in the one or more other magnet sets in accordance with a magnitude of the second component. In the manufacturing method, a series of steps including the second measuring step, the selection step, and the magnet mounting step are repeated,
The manufacturing method according to claim 2 or 3, wherein a maximum number of the one or more magnet sets selected in the selection step and a maximum number of the one or more other magnet sets selected in the selection step are the same as each other. The first measuring step includes dividing the plurality of magnets into weight categories according to a weight measurement result,
In the selection step,
When the first component is reduced, a difference in weight class between a pair of magnets among the plurality of target magnets, the pair of magnets capable of reducing the first component, is determined according to the magnitude of the first component;
The manufacturing method according to any one of claims 1 to 3, wherein, when the second component is reduced, the difference in weight class between a pair of magnets among the plurality of target magnets, in which the second component can be reduced, is determined according to the magnitude of the second component. The method further includes, before the selection step, acquiring storage information indicating the number of magnets stored for each weight category;
The manufacturing method according to claim 5 , wherein the selection step includes selecting the plurality of target magnets based on the storage information. In selecting the plurality of target magnets based on the storage information,
When the first component is reduced, a pair of magnets capable of reducing the first component is selected from the weight category in which the number of magnets stored in the storage information is equal to or greater than a predetermined number, among the plurality of target magnets,
The manufacturing method described in claim 6, wherein when the second component is reduced, a pair of magnets capable of reducing the second component is selected from the weight category in which the number of magnets stored in the storage information is equal to or greater than the predetermined number, among the plurality of target magnets. The manufacturing method according to claim 6, wherein selecting the plurality of target magnets based on the storage information includes, when the plurality of target magnets includes a plurality of standard magnets that do not contribute to reducing the amount of imbalance, selecting the plurality of standard magnets from the weight category in which the number of magnets stored in the storage information is the largest. The manufacturing method according to any one of claims 1 to 3, wherein the first direction and the second direction are set based on an index portion that represents a reference position on the circumference around the central axis of the core body. an iron core body provided with a plurality of magnet mounting portions;
a plurality of magnets attached to the plurality of magnet attachment portions;
a weight difference is provided between one or more magnets located in one area defined by a first virtual line and one or more magnets located in another area defined by the first virtual line, among the plurality of magnets;
a weight difference is provided between one or more magnets located in one area defined by a second virtual line and one or more magnets located in another area defined by the second virtual line, among the plurality of magnets;
The first virtual line is a line that is perpendicular to a central axis of the core body and passes through the central axis,
A rotor core, wherein the second virtual line intersects the first virtual line in a plane perpendicular to the central axis and is a line passing through the central axis.

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