JP5190792B2 - Unbalance correction method and motor - Google Patents

Description

  The present invention relates to an unbalance correction method for correcting a deviation of a center of gravity with respect to a rotation axis in a rotating body.

  In recent improvements in various devices such as improvement in the static pressure-air flow characteristics of fan motors, it is required to increase the motor rotation speed. In order to increase the speed of rotation of the motor, it is necessary to reduce the deviation of the center of gravity (hereinafter referred to as “unbalance”) in the rotor section with respect to the rotation axis. As the centrifugal force varies, energy loss increases, and vibration and noise due to vibration of the rotor portion increase. One method for correcting such imbalance is to remove a portion of the rotor using a laser.

  For example, in a laser processing method for a rotating body disclosed in Patent Document 1, laser light is repeatedly irradiated at predetermined angles in the circumferential direction of the rotating body. After the number of irradiations in the circumferential direction reaches a certain number, the laser beam irradiation position is shifted by a predetermined distance in the axial direction of the rotating body, and the irradiation is repeated in the circumferential direction again, so that the laser is applied to the entire correction region of the rotating body. Light is irradiated.

Further, in Patent Document 2, a laser beam converged from a plurality of laser light sources is irradiated in pulses to a plurality of positions in the axial direction of the rotating body, thereby removing a very small part of the rotating body. A balance adjustment device is disclosed.
JP 59-050987 A JP 2004-82167 A

  By the way, when the rotating body to be processed is a thin cylindrical shape like a rotor holder of a motor, residual stress is generated in the cylindrical portion due to expansion and contraction due to heat during laser processing, and deformation occurs. In particular, when the object to be processed is a covered cylinder, the deformation increases on the opening side. As a result, an error from an ideal circle having a shape in plan view of the rotating body (that is, roundness error) increases. When the roundness error increases, the radial runout width of the outer surface when the rotating body is rotated also increases, causing fluctuations in motor characteristics such as cogging torque, vibration, noise, and the like.

  The present invention has been made in view of the above problems, and has as its main object to correct the unbalance of the rotating body while suppressing an increase in roundness error.

  The invention described in claim 1 is an unbalance correction method for correcting the deviation of the center of gravity with respect to the rotation axis in a thin cylindrical rotating body formed of metal, and a) unbalance of the rotating body with respect to the rotation axis. A step of measuring an unbalance amount indicating a direction and a degree of unbalance; and b) setting a first removal region centered in the unbalance direction on the outer surface of the rotating body and centering the rotation axis A step of setting two second removal regions that are centrally located at angular positions that are separated from each other by a predetermined angle on both sides from the unbalance direction, and are separated from or adjacent to the first removal region; c) The first removal amount in the first removal region and the second removal amount in each of the two second removal regions are removal amounts corresponding to the unbalance amount in the unbalance direction. D) removing a part of the rotating body from the first removal region by the first removal amount by laser light irradiation, and removing the second removal amount from each of the two second removal regions. And removing only a part of the rotating body.

  The invention according to claim 2 is the unbalance correction method according to claim 1, wherein the predetermined angle is α, the unbalance amount is U, and the radius of the outer surface of the rotating body is R. Using the positive coefficient β, the first removal amount is (1-2βcos α) U / R, and the second removal amount is βU / R.

  The invention described in claim 3 is the unbalance correction method according to claim 1 or 2, wherein the predetermined angle is not less than 30 degrees and not more than 70 degrees.

  The invention according to claim 4 is the imbalance correction method according to any one of claims 1 to 3, wherein the rotation axis of each of the first removal region and the two second removal regions is centered. The angle around the rotation axis corresponding to the circumferential width is 60 degrees or less.

  The invention according to claim 5 is an unbalance correction method for correcting the deviation of the center of gravity with respect to the rotation axis in a thin cylindrical rotating body formed of metal, and a) unbalance of the rotating body with respect to the rotation axis. A step of measuring an unbalance amount indicating a direction and a degree of unbalance; and b) setting a first removal region whose center is located in the unbalance direction on the outer surface of the rotating body, and the first removal region. A plurality of second removal regions spaced apart or adjacent to each other are equally spaced in the circumferential direction around the rotation axis, and the first removal region is located at the center between any two adjacent second removal regions And c) removing a part of the rotating body from the first removal region by a first removal amount corresponding to the unbalance amount by irradiation with laser light, and removing the plurality of second removal regions. Each one Only certain second removal amount and a step of removing a portion of the rotating body.

  The invention according to claim 6 is the imbalance correction method according to claim 5, wherein the number of the plurality of second removal regions is any one of 2 to 4.

  The invention described in claim 7 is an electric motor, and includes a rotor part having a rotor holder whose imbalance is corrected by the method described in any one of claims 1 to 6, the stator part, and the rotor And a bearing mechanism that supports the stator with respect to the stator so as to be rotatable about a central axis.

  In the present invention, it is possible to correct the unbalance of the rotating body while suppressing an increase in roundness error.

  FIG. 1 is a longitudinal sectional view of the fan motor 60 according to the first embodiment of the present invention cut along a plane including the central axis J1. As shown in FIG. 1, the fan motor 60 includes an electric motor unit 1, an impeller 61 that is attached to the motor unit 1 and rotates about a central axis J <b> 1 to generate an air flow, and the motor unit 1. And a housing 62 that covers the periphery of the impeller 61.

  The impeller 61 has a covered cylindrical impeller cup 611 attached to the rotor unit 3 described later of the motor unit 1, and a plurality (nine in this embodiment) of moving blades 612 on the outer surface of the impeller cup 611. The rotor blades 612 are arranged at equal intervals in the circumferential direction around the central axis J1 (hereinafter simply referred to as “circumferential direction”), and the impeller cup 611 and the rotor blades 612 are formed of resin as one member. Further, the housing 62 extends from the lower part of the inner side surface of the wind tunnel part 621 toward the central axis J1 and is connected to the base part 21 of the motor part 1 (covering the outer periphery of the motor part 1 and the impeller 61). In the present embodiment, there are 11) stationary blades 622, and the wind tunnel portion 621, the stationary blades 622, and the base portion 21 are formed as one member with resin.

  The motor unit 1 includes a stator unit 2, a rotor unit 3, and a bearing mechanism 4 that supports the rotor unit 3 with respect to the stator unit 2 so as to be rotatable about a central axis J <b> 1. In the following description, for convenience, the rotor part 3 side is described as the upper side and the stator part 2 side is the lower side along the central axis J1, but the central axis J1 does not necessarily need to coincide with the direction of gravity.

  The stator portion 2 includes a base portion 21 and an annular stator 22, and an outer periphery of a cylindrical bearing holding portion 211 protruding upward from the base portion 21 is press-fitted into the stator 22. The rotor unit 3 includes a substantially cylindrical shaft 31, a covered cylindrical rotor holder 32 attached to the upper end of the shaft 31, and a field magnet 33 fixed to the inner surface of the rotor holder 32. The impeller cup 611 is fixed by press fitting. The bearing mechanism 4 has ball bearings attached at two locations along the central axis J1 (hereinafter simply referred to as “axial direction”) inside the bearing holding portion 211 of the base portion 21, and the shaft 31 is inserted therein. The

  In the stator 22, a coil is formed by winding a conductive wire from above the insulator around a core in which thin silicon steel plates are laminated, and the conductive wire is electrically connected to a circuit board 51 attached to the lower side of the stator 22. The circuit board 51 supplies and controls current to the stator 22. The field magnet 33 of the rotor unit 3 is a multi-pole magnetized substantially cylindrical permanent magnet, and generates a rotational force (torque) around the central axis J <b> 1 with the stator 22. That is, the stator 22, the field magnet 33, and the circuit board 51 function as a drive mechanism 5 that rotates the rotor portion 3 with respect to the stator portion 2 about the central axis J1.

  FIG. 2 is a front view of the rotor unit 3, and FIG. 3 is a plan view of the rotor unit 3. The rotor holder 32 of the rotor portion 3 is a rotating body formed of metal, and extends in a direction perpendicular to the central axis J1. The lid portion 321 is attached to the shaft 31, and the thin cylindrical shape projects downward from the outer edge of the lid portion 321. Side 322.

  It is desirable that the center of gravity of the rotor holder 32 coincides with the central axis J1 that is the rotation center of the rotor holder 32. However, the rotor holder 32 immediately after assembly normally does not have a uniform mass distribution due to assembly error, uneven thickness, shape asymmetry, and the like. The center axis J1 and the center of gravity do not coincide. When such a rotor holder 32 is used for the fan motor 60, the mass of the rotor holder 32 is imbalanced (that is, the deviation of the center of gravity with respect to the rotation axis), and thus the centrifugal force may be biased during rotation, and vibration and noise may occur. . Therefore, the rotor holder 32 immediately after the assembly is corrected to bring the center of gravity close to the center of rotation (hereinafter referred to as “unbalance correction”).

  FIG. 4 is a diagram showing an outline of the unbalance correction device 7. The unbalance correction device 7 includes a positioning mechanism 71 that holds the rotor holder 32 on the upper surface, a laser head 72 that irradiates the rotor holder 32 with laser light, and a controller 73 that controls the positioning mechanism 71 and the laser head 72. Of the rotor holder 32 by irradiating a laser beam on the outer surface 323 of the rotor and removing a part of the rotor holder 32 by evaporation or by blowing a gas to the melted part or by scattering by centrifugal force or the like. I do.

  In response to a signal from the controller 73, the positioning mechanism 71 moves the rotor holder 32 up and down along the central axis J1 and rotates the rotor holder 32 in the circumferential direction. Further, the position and orientation of the laser head 72 are fixed, and laser light is irradiated to a predetermined position on the outer surface 323 of the rotor holder 32 determined by the positioning mechanism 71. Further, the removal amount at a predetermined position of the rotor holder 32 is adjusted by controlling the pitch, the number of pulses, the shot current, the voltage, and the like of the laser light irradiated by the laser head 72 by the control unit 73.

  The unbalance of the rotor holder 32 before the unbalance correction is performed is constant from the central axis J1 of the rotor holder 32 in an ideal balanced state (a state where the center of gravity of the rotor holder 32 is located on the central axis J1 that is the rotation center). Assuming that a virtual weight of mass m (g) is added at a position separated by the eccentric gravity center distance r (mm), in the present embodiment, the mass m (g) and the eccentric gravity center distance r (mm). The unbalance amount U (g · mm) indicating the degree of unbalance in the rotor holder 32 is defined as the product of. Note that the direction in which the weight is arranged is indicated by a straight line L1 in FIG. 3 as an unbalanced direction, and FIG. 2 shows the rotor holder 32 with the unbalanced direction as the front.

  FIG. 5 is a diagram showing the flow of correcting the unbalance of the rotor holder 32. In the unbalance correction of the rotor holder 32, first, the unbalance direction and the unbalance amount U (g · mm) with respect to the central axis J1 of the rotor holder 32 are determined by an unbalance measuring device (not shown) based on the centrifugal force generated when the rotor holder 32 rotates. ) Is measured (step S11).

  Next, as shown in FIGS. 2 and 3, laser light is to be irradiated by the unbalance correction device 7 on the outer surface 323 of the rotor holder 32 at an axial position close to the lid portion 321 (upper part in FIG. 2). Area 3231 is set (step S12). The region 3231 has a central position 3232 set in the unbalanced direction indicated by the straight line L1, and each side has a substantially rectangular shape parallel to the axial direction or the circumferential direction. The region 3231 is centered on the central axis J1 corresponding to the circumferential width. Is represented by θ1 in FIG.

  On the outer side surface 323, two regions 3233 for irradiating laser light are further set on both sides of the region 3231 and at the same height (step S13). As shown in FIG. 3, the center position 3234, which is the center of each region 3233, is set to an angular position that is separated from the unbalance direction by a predetermined angle (shown with α) on both sides from the unbalance direction. Is done. The region 3233 has a substantially rectangular shape in which each side is parallel to the axial direction or the circumferential direction, and an angle about the central axis J1 corresponding to the circumferential width is indicated by θ2 in FIG.

  Hereinafter, the area 3231 is referred to as a “first removal area”, the central position 3232 is referred to as a “first central position”, the two areas 3233 are referred to as “second removal areas”, and the central position 3234 is referred to as a “second central position”. Call.

When the first removal region 3231 and the second removal region 3233 are set, the first removal amount m ₁ (g) corresponds to the unbalance amount U (g · mm) and is the mass removed from the first removal region 3231. ) And the second removal amount m ₂ (g), which is the mass removed from each second removal region 3233, is obtained by the processing described later (step S14). Further, the positioning mechanism 71 and the laser head 72 are controlled by the control unit 73 as described above. Specifically, as shown in FIG. 2, by irradiating a laser beam with a constant output every time, the irradiated portion is removed to form a laser mark 3235, and the entire first removal region 3231 is irradiated. The rotor holder 32 is sequentially rotated and moved in the axial direction until it is performed. Thereby, a part of the rotor holder 32 is removed so that the removal amount from the first removal region 3231 is substantially equal to the first removal amount m ₁ (g) (step S15). Further, by the same processing, a part of the rotor holder 32 is removed so that the removal amount from each of the two second removal regions 3233 is substantially equal to the second removal amount m ₂ (g) (step S16).

Note that it is assumed that the imbalance correction can be performed only at the first central position 3232 and the second central position 3234 that do not have a size (that is, it is possible to perform removal concentrated on one point). ) If the first removal amount m ₁ and the second removal amount m ₂ obtained under these conditions are uniformly removed from the first removal region 3231 and the second removal region 3233 having a size, the correction due to the removal is not corrected. The balance amount slightly deviates from the desired unbalance amount U. For example, when the first removal amount m ₁ is uniformly removed from the first removal region 3231 having a width of the angle θ1 (rad), the mass represented by Equation 1 is actually removed at the first central position 3232. Only the correction effect similar to that in the case of being applied is obtained.

As described above, when the removal amount is obtained on the assumption that removal can be performed concentrated on one point, the areas of the first removal region 3231 and the second removal region 3233 (more precisely, the center corresponding to the width of the region). The smaller the angle around the axis J1), the smaller the theoretical unbalance correction calculation error and the shorter the correction removal time. However, the first removal region 3231 and the second removal region 3233 are appropriately expanded and set in order to suppress an increase in processing error and a decrease in intensity at the side portion 322 due to the concentrated irradiation of the laser light. Further, when the angle θ1 is 60 degrees, since seen from about 1 number that the same effect can be obtained in the case of performing 95% removal of the first removal amount m ₁ and concentrated on one point, the angle θ1 and If each angle θ2 is 60 degrees or less, the removal amount may be obtained on the assumption that the removal can be concentrated on one point. Note that the minimum values of the angle θ1 and the angle θ2 depend on the ability of the unbalance correction device 7, but when the removal amount is small, the angle can theoretically be an angle corresponding to the width of one laser mark 3235. .

Of course, the calculated removal amount may be obtained accurately in consideration of the size of the first removal region 3231 and the second removal region 3233, and further, machining errors and measurement such as variations in the size and depth of the machining hole. The first removal amount m ₁ and the second removal amount m ₂ may be obtained in consideration of other errors such as errors.

Next, in step S14 of FIG. 5, the first removal amount m ₁ (g) and the second removal amount m ₂ (g) optimum for eliminating the imbalance without greatly deforming the side portion 322 of the rotor holder 32. A method for obtaining the value will be described. In the following description, the calculation is simplified on the assumption that the first removal amount m ₁ and the second removal amount m ₂ can be removed by concentrating on the first central position 3232 and the second central position 3234. ing.

  As described above, the difference between the angular position of the first central position 3232 on the straight line L1 shown in FIG. 3 and the angular position of the straight line L2 passing through the central axis J1 and the upper second central position 3234 in FIG. The difference between the central axis J1 and the angular position of the straight line L3 passing through the lower second central position 3234 in FIG. 3 is also α, and α is ((θ1 + θ2) / 2) or more, and the first removal The second removal region 3233 is separated or adjacent to the region 3231 and does not overlap.

Of the correction amounts with respect to the unbalance amount U (g · mm), the correction amount in the direction to which the first removal amount m ₁ (g) contributes (that is, the direction of the first central position 3232) is the first correction amount U _1. (G · mm), the relationship between the first correction amount U ₁ (g · mm) and the first removal amount m ₁ (g) is the radius R (mm) of the outer surface 323 (22. 4 mm).

Similarly, among the correction amounts for the unbalance amount U (g · mm), the correction amounts in the two directions (that is, the direction of the second center position 3234) to which the second removal amount m ₂ (g) contributes are respectively Assuming that 2 correction amount U ₂ (g · mm), the relationship between the second correction amount U ₂ (g · mm) and the second removal amount m ₂ (g) is expressed by Equation 3.

The first correction amount U ₁ (g · mm) goes from the central axis J1 to the first central position 3232, and the second correction amount U ₂ (g · mm) goes from the central axis J1 to the two second central positions 3234. When regarded as two vectors, the sum of the components of the first correction amount U ₁ (g · mm) and the two second correction amounts U ₂ (g · mm) in the direction perpendicular to the unbalance direction is _two second correction amounts U ₁ (g · mm). It is 0 due to the symmetry of the correction amount U ₂ (g · mm), and the sum of the components parallel to the unbalance direction needs to be equal to the unbalance amount U (g · mm) as shown in Equation 4.

When the second correction amount U ₂ (g · mm) is expressed as βU using a positive coefficient β, Expression 4 is expressed by Expression 5.

Further, by transforming Equation 5, the first correction amount U ₁ (g · mm) can be expressed by Equation 6 using U.

Accordingly, the first correction amount U ₁ (g · mm) and the second correction amount U ₂ (g · mm) are set to the unbalance amount U (g · mm) in the unbalance direction using the angle α and the coefficient β as parameters. It is obtained as a corresponding correction amount. When the first correction amount U ₁ (g · mm) and the second correction amount U ₂ (g · mm) which are βU expressed by U in Equation 6 are compared with Equations 2 and 3, the first removal The amount m ₁ (g) can be expressed by Equation 7 and the second removal amount m ₂ (g) can be expressed by Equation 8.

As described above, the first correction amount U ₁ (g · mm), the second correction amount U ₂ (g · mm), the first removal amount m ₁ (g) and the first correction amount U ₁ (g · mm) are determined by determining the angle α and the coefficient β. 2 The removal amount m ₂ (g) can be determined.

  FIG. 6 shows the side portion 322 of the rotor holder 32 when the removal amount (U / R) (g) corresponding to a predetermined unbalance amount U (g · mm) is removed by laser processing only in the first removal region 3231. FIG. 2 is a diagram showing a change in the shape of FIG. 2, with the position of the central axis J1 as the origin, the distance from the central axis J1 at each angular position, and the ideal inner surface radius (radius) of the rotor holder 32 Is a graph showing a difference from a circle corresponding to. The change in the shape of the side portion 322 is indicated by the radial runout width (hereinafter referred to as “circumferential runout”) of the outer side surface. The rotor holder 32 is rotated to rotate the inner side surface at a predetermined axial position. It is obtained by measuring the radial distance between the measuring instrument at each point in the direction.

  In FIG. 6, the direction from the origin to the right is the unbalanced direction indicated by the straight line L1, and the first center position 3232 that is the intersection of the straight line L1 and the outer surface is indicated by an arrow. In this modification, the height of the first removal region 3231 is about 3 mm, the width in the circumferential direction is about 11.5 mm, and the removal amount is about 20 mg.

  FIG. 6 shows the result of laser processing and measurement of circumferential runout with the field magnet 33 removed from the rotor holder 32, but actual laser processing and measurement of circumferential runout, and In the measurement of the unbalance amount and the laser processing, the rotor holder 32 is in a state in which the field magnet 33 (see FIG. 1) is attached. In the following explanation, the rotor magnet 32 is attached to the field magnet 33. The same holds true even in the case of other cases (the same applies to other embodiments). Therefore, in the actual correction work shown in FIG. 5, the unbalance correction including the unbalance caused by the mounting of the field magnet 33 is performed.

  As shown in FIG. 6, when a part of the rotor holder 32 is removed by laser light irradiation in the first removal region 3231, the residual stress distribution in the side portion 322 changes greatly due to thermal expansion and contraction and metal removal. Deformation occurs. Large deformation does not occur on the opposite side (left side in FIG. 6) of the first removal region 3231 irradiated with the laser light, but the radial position is inward of the ideal circle in the first removal region 3231 and the vicinity thereof. It moves (that is, the side part 322 becomes concave when viewed from the outside in the radial direction), and the side part 322 becomes convex toward the outside on both sides in the circumferential direction of the first removal region 3231. As a result, the difference between the maximum value and the minimum value of the diameter of the side portion 322 increases, and the circumferential runout increases compared to before the unbalance correction. Further, as the circumferential deflection increases, an error from an ideal circle of the shape of the rotor holder 32 in plan view (that is, 2 when the outer surface of the rotor holder 32 is set between two concentric circles). Is the minimum difference between the radii of two concentric circles, and is hereinafter referred to as “roundness error”).

  FIG. 7 is a diagram showing circumferential runout of the rotor holder 32 predicted at the time of performing laser processing only on the two second removal regions 3233 (at the same axial position as in FIG. 6). In the example shown in FIG. 7, in consideration of the positions (both sides in the circumferential direction of the first central position 3232) in which the side portions 322 are convex in the shape of FIG. 6 (hereinafter referred to as “reference circumferential deflection”), The angle α is set to 60 degrees, and two second center positions 3234 indicated by arrows in FIG. 7 are determined.

The circumferential runout shown in FIG. 7 is calculated on the basis of the reference circumferential runout and assuming that the deformation amount of each second removal region 3233 is proportional to the coefficient β of the second modification amount βU (g · mm). And the deformation of the side portion 322 caused by laser processing in the two second removal regions 3233 is synthesized. Therefore, the circumferential runout shown in FIG. 7 is such that the height of each second removal region 3233 is about 3 mm and the width in the circumferential direction is about 11.5 mm, and the second correction amount βU is within the second removal region 3233. The corresponding second removal amount m ₂ (g) corresponds to the one that has been removed by (βU / R) (g). Each of the second removal regions 3233 irradiated with the laser beam and the region in the vicinity thereof are located radially inward of the ideal circle indicated by the dotted line, and are concave when viewed from the outside. On both sides in the circumferential direction, the side portions 322 are convex outward from an ideal circle. In FIG. 7, the first removal region 3231 (which has not been corrected) is located in the middle of the two second removal regions 3233, and thus bulges in a convex shape due to the influence of both the second removal regions 3233.

FIG. 8 is a diagram showing a circumferential run obtained by combining both of the deformations shown in FIGS. 6 and 7 with a solid line. The shape predicted to be obtained by the correction in the first removal region 3231 and the second removal region 3233 is shown. Show. However, in the first removal region 3231, it is assumed that the correction is performed by the first correction amount U ₁ (g · mm) expressed by Equation 6, and accordingly, the deformation amount in FIG. 6 is proportional to U ₁ / U. Then, after being converted, it is synthesized with the shape of FIG. For comparison, an ideal circle in the side portion 322 of the rotor holder 32 is indicated by a dotted line, and a modification example in which correction is performed only in the first removal region 3231 shown in FIG. As shown in FIG. 8, the deformation due to the correction in the first removal region 3231 and the second removal region 3233 cancels each other's unevenness due to the synthesis, the circumferential deflection and the roundness error are reduced, and the shape of the side portion 322 is It is close to the ideal circle.

FIG. 9 is a diagram showing the relationship between the coefficient β and the roundness error. In the graph shown in FIG. 9, the horizontal axis indicates the coefficient β, and the vertical axis indicates the first removal area 3231 and the second removal area 3233. A ratio between the roundness error after correcting the unbalance and the roundness error after correcting only the first removal region 3231 (roundness error in the shape shown in FIG. 6) (hereinafter referred to as “roundness”). "Degree error improvement ratio"). FIG. 9 shows the result of calculating the roundness error for a plurality of coefficients β with the angle α fixed at 60 degrees. By changing the coefficient β, the first correction amount U ₁ (g · mm) and the second correction amount U ₂ (g · mm) are changed, and as a result, the deformation of the rotor holder 32 is also different. In the result shown in FIG. 9, when the coefficient β is 0.4, the roundness error of the rotor holder 32 is minimized (that is, it approaches the most ideal circle). Note that the angle α may be set to other values as long as the roundness error can be reduced. The angle α is preferably 30 degrees or more and 70 degrees or less in order to reduce the convex shape shown in FIG. Is done.

Further, by calculating the roundness error with respect to the coefficient β for a plurality of angles α, the combination of the angle α and the coefficient β that can most reduce the roundness error is determined. Good. In the present embodiment, when the angle α is 60 degrees and the coefficient β is 0.4, the roundness error improvement ratio is 0.28, the roundness error is minimized, and the first correction amount U ₁ ( g · mm) is 0.6 U (first removal amount m ₁ (g) is (0.6 U / R)), and the second correction amount U ₂ (g · mm) is 0.4 U (second removal amount m _2). (G) is (0.4 U / R)), and the total correction amount at three locations is 1.4 U (g · mm).

The sizes of the first removal region 3231 and the second removal region 3233 are not limited to those shown in the above description, and the first correction amount U ₁ (g · mm) and the second correction amount U ₂ (g The height and the width in the circumferential direction may be changed as appropriate according to mm).

  As described above, by executing the unbalance correction after step S12 shown in FIG. 5 using the angle α and the coefficient β, the unbalance of the rotor holder 32 is suppressed while suppressing an increase in the roundness error of the rotor holder 32. Can be corrected.

  FIG. 10 is a diagram showing a flow of unbalance correction according to the second embodiment of the present invention, and FIG. 11 is a plan view of the rotor unit 3 in which the unbalance is corrected. The present embodiment is different from the unbalance correction flow shown in FIG. 5 in that unbalance correction and roundness error correction are performed independently, and the fan motor 60 and the unbalance correction device 7 are different. The other configurations are the same.

  In the unbalance correction shown in FIG. 10, as in the case of FIG. 5, first, the unbalance direction and unbalance amount U (g · mm) of the rotor holder 32 with respect to the center axis J <b> 1 are determined using an unbalance measurement device (not shown). It is measured (step S21).

  Next, as shown in FIG. 11, a first removal region 3231 is set on the outer surface 323 of the rotor holder 32 with the first center position 3232 located in the unbalance direction indicated by the straight line L1 as the center (step). S22). The first removal region 3231 has a substantially rectangular shape similar to that shown in FIG. 2, and an angle around the central axis J1 corresponding to the width in the circumferential direction is indicated by θ1 in FIG. Further, on the outer surface 323, the second center position 3234a is set at an angular position 90 degrees away from the unbalance direction indicated by the straight line L1 on both sides in the circumferential direction with the center axis J1 as the center, and two second center positions are set. A second removal region 3233a is set around each of 3234a (step S23). The second removal region 3233a has a substantially rectangular shape similar to that shown in FIG. 2, and in FIG. 10, the angle around the central axis J1 corresponding to the width in the circumferential direction is indicated by θ2.

  When the removal region is set, the laser head 72 of the unbalance correction device 7 shown in FIG. 4 irradiates the laser beam and the mass (U / R) as the first removal amount corresponding to the unbalance amount U (g · mm). ) (G) A part of the rotor holder 32 is removed from the first removal region 3231 by R (R is the radius of the outer surface of the rotor holder 32) (step S24). At this time, the rotor holder 32 is deformed by the heat generated by the laser light irradiation, and the side portion 322 (see FIG. 11) of the rotor holder 32 is radially inward from the ideal circle in the vicinity of the first removal region 3231. It becomes concave toward the outside, and both sides in the circumferential direction of the concave portion become convex outward in the radial direction (see FIG. 6). Thereafter, the circumferential shake is measured by a measurement device (not shown) (step S25).

When the circumferential shake is measured, a constant (that is, the same) second removal amount m ₂ (g) is obtained for the two second removal regions 3233a by the method described later based on the measurement result. (Step S26). Further, by irradiating the unbalance correction device 7 with laser light, a part of the rotor holder 32 is removed from each of the two second removal regions 3233a by the second removal amount m ₂ (g) (step S27). . Note that the first removal region 3231 and the second removal region 3233a are appropriately expanded and set in order to prevent a decrease in strength of the rotor holder 32 due to local processing by laser light irradiation. However, in order to keep the error of unbalance correction small, the angle θ1 and the angle θ2 are preferably 60 degrees or less, respectively. The minimum width that can be set for the angle θ1 and the angle θ2 is equal to the width of one laser mark.

Next, the process for obtaining the second removal amount m ₂ (g) in step S26 will be described. As described above, the second removal region 3233a is arranged at an interval of 180 degrees in the circumferential direction around the central axis J1, and the first removal region 3231 is located at the center between the two second removal regions 3233a. . Therefore, even if the same amount of removal is performed in each second removal region 3233a, the position of the center of gravity of the rotor holder 32 in which the unbalance is corrected is not affected.

FIG. 12 is a diagram showing the circumferential shake when the removal by the laser is performed only in the second removal region 3233a. In the following, the unbalance amount of the rotor holder 32 that is generated when the second removal amount m ₂ (g) is removed from only one second removal region 3233a according to the first embodiment is described as “second”. It is called “correction amount U ₂ (g · mm)”. Further, the relationship between the second correction amount U ₂ (g · mm) and the second removal amount m ₂ (g) is expressed by Equation 3, and the second correction amount U ₂ (g · mm) is expressed as an unbalance amount U ( g · mm) is represented by γU using a positive coefficient γ. In FIG. 12, each second removal region is based on the circumferential deflection measured in step S25 (however, in FIG. 12, it is assumed that the one shown in FIG. 6 was acquired in step S25). The deformation amount of 3233a is calculated as being proportional to the coefficient γ of the second correction amount U ₂ (ie, γU) (g · mm), and the deformation caused by the two second removal regions 3233a is synthesized. Each of the second removal regions 3233a irradiated with the laser light and the region in the vicinity thereof are located radially inward from the ideal circle indicated by the dotted line, and are concave when viewed from the outside, except for the second removal region 3233a. This region is located slightly outside the ideal circle.

  FIG. 13 is a diagram showing, in a solid line, the circumferential runout in which the deformation measured in step S25 and the deformation shown in FIG. 12 are combined, and the unbalance correction in the first removal region 3231 and the second removal region. The shape predicted to be obtained by the removal in 3233a (because it is a process for reducing the roundness error is hereinafter referred to as “roundness error correction”) is shown. For comparison, a circle indicating the ideal side portion 322 of the rotor holder 32 is indicated by a dotted line, and a modified example in the case where the unbalance correction is performed only by the first removal region 3231 is indicated by a one-dot chain line. The circumferential runout shown in FIG. 13 has a shape in which both deformation near the first removal region 3231 and deformation near the two second removal regions 3233a appear.

FIG. 14 is a diagram showing the relationship between the coefficient γ and the roundness error improvement ratio. The horizontal axis of the graph shown in FIG. 14 is the coefficient γ, and the vertical axis represents the first removal area 3231 and the second removal area 3233a. The roundness error between the roundness error after removal and the roundness error (roundness error in the shape shown in FIG. 6) after correcting the unbalance in only the first removal region 3231 It is an improvement ratio. As shown in FIG. 14, the second correction amount U ₂ (g · mm) is changed by changing the coefficient γ, and as a result, the deformation of the rotor holder 32 is also different.

In the result shown in FIG. 14, when the coefficient γ is 1.4, the roundness error improvement ratio is 0.92, and the roundness error of the rotor holder 32 is minimized. In step S27, correction is performed using the second removal amount m ₂ (g) determined based on this result. The coefficient γ may be determined from other conditions. For example, a coefficient that minimizes the total correction amount (that is, corresponding to the total removal amount and the correction cost) may be selected.

In the unbalance correction flow of FIG. 10, the second removal amount m ₂ (g) of step S26 may be set before the step of removing in the first removal region 3231 of step S24. In this case, as illustrated in FIG. 6, the coefficient γ is determined based on the preliminarily acquired reference circumferential direction shake, and the unbalance correction in the first removal region 3231 in step S24 and the second removal region 3233a in step S27. Roundness error correction is performed continuously.

Alternatively, the second removal amount m ₂ (g) may be obtained in advance, and the removal in the second removal region 3233a may be performed first. In this case, a method may be employed in which the unbalance correction is performed last while considering that the position of the center of gravity of the rotor holder 32 is shifted due to the removal in the second removal region 3233a. That is, first, the unbalance is measured, the removal amount in each second removal region 3233a is determined in advance, the removal in the second removal region 3233a is performed first, and then the unbalance of the rotor holder 32 is measured again, Unbalance correction in the first removal region 3231 may be performed.

  FIG. 15 is a plan view showing the rotor unit 3 in which the unbalance is corrected by another example of the unbalance correction method according to the second embodiment. The rotor holder 32 shown in FIG. 15 is different from that shown in FIG. 11 in that the second removal regions are provided at three places, and the others are the same.

  The second removal region 3233b shown in FIG. 15 is set around the second central position 3234b arranged at equal intervals of 120 degrees in the circumferential direction around the central axis J1, and is between the two second central positions 3234b. The first removal region 3231 is located in the center. That is, one of the three second central positions 3234b is located opposite to the unbalance direction (first center position 3232), and the other two are located 60 degrees symmetrically away from the unbalance direction. ing. Therefore, also in the example shown in FIG. 15, the gravity center position of the rotor holder 32 is not affected by the roundness error correction in the second removal region 3233b.

Next, a method for setting the second removal amount m ₂ (g) to be removed in the second removal region 3233b in step S26 of FIG. 10 will be described. FIG. 16 is a diagram showing a predicted circumferential shake when removal is performed only in the second removal region 3233b, and the circumferential shake is obtained by the same calculation as that shown in FIG. Each second removal region 3233b is concave when viewed from the outside, and the region between adjacent second removal regions 3233b is convex.

  FIG. 17 is a diagram showing, by a solid line, a combination of the circumferential runout acquired in step S25 (assuming that the one shown in FIG. 6 is obtained) and the circumferential runout shown in FIG. Yes, it shows the circumferential deflection of the rotor holder 32 that is predicted when unbalance correction and roundness error correction are performed. Further, for comparison, a circle indicating the ideal side portion 322 of the rotor holder 32 is indicated by a dotted line, and a modification example in which the imbalance is corrected only by the first removal region 3231 shown in FIG. Show. The circumferential shake shown in FIG. 17 has a shape in which both the first removal region 3231 and the deformation in the vicinity thereof, and the three second removal regions 3233b and the deformation in the vicinity thereof appear.

FIG. 18 is a diagram showing the relationship between the coefficient γ and the roundness error improvement ratio. By changing the coefficient γ, the second correction amount U ₂ (g · mm) corresponding to the second removal amount m ₂ (g). ) Changes, and as a result, the roundness error improvement ratio also changes. In the result shown in FIG. 18, when the coefficient γ is 1.5, the roundness error improvement ratio is 0.63, and the roundness error of the rotor holder 32 is minimized. In step S27, the removal is performed using the second removal amount m ₂ (g) determined based on this result.

  FIG. 19 is a plan view showing the rotor unit 3 in which the unbalance is corrected by still another example of the unbalance correction method according to the second embodiment. The rotor holder 32 shown in FIG. 19 is different from that shown in FIG. 11 in that the second removal regions are provided at four places, and the others are the same.

  The second removal region 3233c shown in FIG. 19 is set around a second central position 3234c that is arranged at equal intervals of 90 degrees in the circumferential direction about the central axis J1, and two of the second central positions The first removal region 3231 is located at the center between 3234c. Therefore, also in the example shown in FIG. 19, the position of the center of gravity of the rotor holder 32 is not affected by the roundness error correction in the second removal region 3233c.

Next, a method for setting the second removal amount m ₂ (g) to be removed in the second removal region 3233c in step S26 of FIG. 10 will be described. FIG. 20 is a diagram for predicting the circumferential shake when the removal is performed only in the second removal region 3233c. The circumferential shake is obtained by the same calculation as that shown in FIG. Each second removal region 3233c is concave when viewed from the outside, and the region between adjacent second removal regions 3233c is convex.

  FIG. 21 is a diagram showing, by a solid line, a combination of the circumferential runout acquired in step S25 (assuming that what is shown in FIG. 6 is obtained) and the circumferential runout shown in FIG. Yes, it shows the circumferential deflection of the rotor holder 32 that is predicted when unbalance correction and roundness error correction are performed. Further, for comparison, a circle indicating the ideal side 322 of the rotor holder 32 is indicated by a dotted line, and a modification example in which correction is performed only by the first removal region 3231 shown in FIG. Yes. The circumferential shake shown in FIG. 21 has a shape in which both the first removal region 3231 and the deformation in the vicinity thereof, and the four second removal regions 3233c and the deformation in the vicinity thereof appear.

Figure 22 is a diagram showing the relationship between the coefficient gamma and roundness error improvement ratio, by changing the coefficient gamma, a second correction amount which corresponds to the second removal amount _{m 2 (g) U 2 (} g · mm) changes, and as a result, the roundness error improvement ratio also changes. In the result shown in FIG. 22, when the coefficient γ is 1.3, the roundness error improvement ratio is 0.74, and the roundness error of the rotor holder 32 is minimum. In step S27, the removal is performed using the second removal amount m ₂ (g) determined based on this result.

  As described above, after the unbalance correction is performed in the first removal region 3231, the roundness error correction is performed in the second removal regions arranged at a plurality of equally spaced locations, thereby The unbalance of the rotor holder 32 can be corrected while suppressing an increase in roundness error. The number of the plurality of second removal regions is preferably 2 to 4, but the second removal regions may be provided at five or more locations. In this case as well, the plurality of second removal regions are arranged in the circumferential direction. The first removal region 3231 is located at the center between any two adjacent second removal regions, and a plurality of second removal regions are separated from or adjacent to the first removal region 3231.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, in the step of optimizing the angle α and the coefficient β in the unbalance correction method according to the first embodiment and the coefficient γ in the unbalance correction method according to the second embodiment, these parameters are determined. The method to do is not limited to calculation. Machining using each parameter may be actually performed on the rotor holder 32, and each parameter may be optimized by measuring the circumferential runout after the machining. In addition, a database based on previously obtained calculation data or actual measurement data may be constructed, and the database may be referred to as needed to determine optimal parameters.

  The axial position of each removal region shown in FIG. 2 is not limited to the position on the upper side (lid portion 321 side) in FIG. 2, and may be other axial positions such as the lower side (opening side) and the middle position. Also good. Further, unbalance correction may be performed at a plurality of axial positions. Furthermore, the shape of each removal region may be other than a substantially rectangular shape. For example, the number of laser marks may be changed for each column arranged in the circumferential direction, and the axial distribution of the removal amount may be adjusted.

  The object to which the unbalance correction method is applied is not limited to the rotor holder 32 alone, but may be the rotor holder 32 combined with other parts such as an impeller cup. The unbalance correction method may be applied to a rotor portion in a motor other than the fan motor 60. For example, a disk drive device that rotates a fixed disk, an optical disk, a magneto-optical disk, etc., a polygon mirror rotating device used in a laser printer, or the like. The present invention may be applied to a motor unit used in the above or a rotor unit of an encoder. Further, the object of unbalance correction may be other than the rotor holder 32 as long as it is a thin cylindrical rotating body.

It is a longitudinal cross-sectional view of the fan motor which concerns on 1st Embodiment. It is a front view of a rotor part. It is a top view of a rotor part. It is a figure which shows the outline of an unbalance correction apparatus. It is a figure which shows the flow of unbalance correction. It is a figure which shows the circumferential direction shake after the removal by the laser beam in a 1st removal area | region. It is a figure which shows the circumferential direction shake after the removal only in a 2nd removal area | region. It is a figure which shows the circumferential direction shake after the removal in a total removal area | region. It is a figure which shows the relationship between coefficient (beta) and a roundness error improvement ratio. It is a figure which shows the flow of unbalance correction which concerns on 2nd Embodiment. It is a top view of a rotor part. It is a figure which shows the circumferential direction shake after the removal only in a 2nd removal area | region. It is a figure which shows the circumferential direction shake after the removal in a total removal area | region. It is a figure which shows the relationship between coefficient (gamma) and a roundness error improvement ratio. It is a top view of the rotor part which concerns on another example. It is a figure which shows the circumferential direction shake after the removal only in a 2nd removal area | region. It is a figure which shows the circumferential direction shake after the removal in a total removal area | region. It is a figure which shows the relationship between coefficient (gamma) and a roundness error improvement ratio. It is a top view of the rotor part concerning other examples. It is a figure which shows the circumferential direction shake after the removal only in a 2nd removal area | region. It is a figure which shows the circumferential direction shake after the removal in a total removal area | region. It is a figure which shows the relationship between coefficient (gamma) and a roundness error improvement ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor part 2 Stator part 3 Rotor part 4 Bearing mechanism 32 Rotor holder 323 Outer surface 3231 1st removal area 3232 1st center position 3233-3233c 2nd removal area 3234-3234c 2nd center position (alpha) (1st center position and 2nd Angle θ1 (indicating the range of the first removal region) angle θ2 (indicating the range of the second removal region) angle J1 central axes S11 to S16, S21 to S27

Claims (7)

An unbalance correction method for correcting the deviation of the center of gravity with respect to the rotation axis in a thin cylindrical rotating body formed of metal,
a) measuring an unbalance amount indicating the unbalance direction and the degree of unbalance of the rotating body with respect to the rotating shaft;
b) On the outer surface of the rotating body, a first removal region having a center located in the unbalance direction is set, and at an angular position away from the unbalance direction by a predetermined angle from the unbalance direction around the rotation axis. A step of setting two second removal regions that are located in the center and are spaced apart from or adjacent to the first removal region;
c) obtaining a first removal amount in the first removal region and a second removal amount in each of the two second removal regions as a removal amount corresponding to the unbalance amount in the unbalance direction;
d) A part of the rotator is removed from the first removal region by the first removal amount by laser light irradiation, and one part of the rotator is removed from each of the two second removal regions by the second removal amount. Removing the part,
An unbalance correction method comprising the steps of: The unbalance correction method according to claim 1,
With the predetermined angle α, the unbalance amount U, the radius of the outer surface of the rotating body R, and a positive coefficient β,
The unbalance correction method, wherein the first removal amount is (1-2βcos α) U / R, and the second removal amount is βU / R. The unbalance correction method according to claim 1 or 2,
The unbalance correction method, wherein the predetermined angle is not less than 30 degrees and not more than 70 degrees. The unbalance correction method according to any one of claims 1 to 3,
The angle around the rotation axis corresponding to the circumferential width around the rotation axis of each of the first removal region and the two second removal regions is 60 degrees or less. Balance correction method. An unbalance correction method for correcting the deviation of the center of gravity with respect to the rotation axis in a thin cylindrical rotating body formed of metal,
a) measuring an unbalance amount indicating the unbalance direction and the degree of unbalance of the rotating body with respect to the rotating shaft;
b) On the outer surface of the rotator, a first removal region whose center is located in the unbalance direction is set, and a plurality of second removal regions that are separated from or adjacent to the first removal region are centered on the rotation axis A step of setting the first removal region so that the first removal region is located in the center between any two adjacent second removal regions at equal intervals in the circumferential direction.
c) A part of the rotating body is removed from the first removal region by a first removal amount corresponding to the unbalance amount by laser light irradiation, and a constant second removal is performed from each of the plurality of second removal regions. Removing a portion of the rotating body by an amount;
An unbalance correction method comprising the steps of: The unbalance correction method according to claim 5,
The method of correcting unbalance, wherein the number of the plurality of second removal regions is any one of 2 to 4. An electric motor,
A rotor portion having a rotor holder in which the unbalance is corrected by the method according to claim 1;
A stator portion;
A bearing mechanism for supporting the rotor portion rotatably with respect to the stator portion about a central axis;
A motor comprising:

Images