JP7120858B2 - Motor stator manufacturing method, motor stator - Google Patents

Description

The present invention relates to a method for manufacturing a motor stator and a motor stator.

2. Description of the Related Art Conventionally, analog electronic timepieces in which pointers such as an hour hand and a minute hand are rotationally driven by a motor drive device have been used. A stepping motor is used as a motor in such a motor drive device.
A stepping motor includes a stator having a rotor housing hole and a positioning portion (inner notch) for determining a stop position of the rotor, a rotor rotatably disposed in the rotor housing hole, and a coil provided in the stator. ing.

To rotate the stepping motor, the drive circuit alternately supplies drive pulses of different polarities to the coils. Leakage magnetic fluxes with different polarities are alternately generated in the stator by the supplied drive pulses. The supplied drive pulse causes the rotor of the stepping motor to rotate in one predetermined direction (positive direction) by 180 degrees, and the rotor stops at a position corresponding to the positioning portion.

In general, a stepping motor has narrowed width portions at two locations (180 degree intervals) around a rotor housing hole formed to dispose the rotor, thereby facilitating saturation of the magnetic flux. An integral stator is used. This structure facilitates the leakage flux that drives the rotor.

Furthermore, in a part of the magnetic path provided around the rotor housing hole (rotor through hole), a Cr diffusion region composed of a melted and solidified portion of Cr, which is a non-magnetic material, is formed to reduce the magnetic permeability of the region. It has been proposed to allow (for example, see Patent Document 1). In the invention described in Patent Document 1, first, an Fe—Ni alloy plate is subjected to machining such as punching to form a rotor housing hole (rotor through hole) and a magnetic path arranged around the rotor housing hole. forming a stator blank having R and a narrowed portion; Next, in the invention described in Patent Document 1, a Cr material for melting and diffusing is placed in at least a part of the stator material, and the Cr material is irradiated with a laser to melt and diffuse the Cr material inside the magnetic path R. Then, for example, a Cr diffusion region, which is a non-magnetic region, is formed in the narrow width portion. The width of the narrow portion is, for example, 0.1 mm. Also, in order to melt Cr, the temperature of the laser is higher than the melting point of Cr, for example 1900 degrees.

JP 2016-136830 A

However, in the conventional technology described above, since the Cr diffusion region is formed in the narrow portion by irradiating the laser after punching, there is a possibility that the narrow narrow portion may be deformed by the heat of the laser. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a motor stator and a motor stator capable of reducing thermal deformation due to laser irradiation when forming a non-magnetic region. With the goal.

To achieve the above object, a method of manufacturing a motor stator according to an aspect of the present invention includes a demagnetization step of forming a nonmagnetic region in a magnetic plate; A step of processing a plate material, which includes a processing step of processing a part of the non-magnetic region, and the demagnetizing step includes a chromium coating step of coating the magnetic plate material with chromium, and the magnetic plate material. and a laser irradiation step of irradiating the laser from the thickness direction .

A method of manufacturing a stator for a motor according to an aspect of the present invention includes a demagnetization step of forming a nonmagnetic region in a magnetic plate, and a step of processing the magnetic plate to form a rotor hole for a motor. and a processing step of processing a part of the non-magnetic region, and the demagnetization step includes a chromium coating step of continuously coating the magnetic plate with chromium, and a chromium coating step of coating the magnetic plate in the thickness direction. and a laser irradiation step of irradiating a laser from .

Further, in the motor stator according to one aspect of the present invention, the magnetic plate material has a nickel content of 37.5% to 38.5%, a chromium content of 7.5 to 8.5%, and an iron content of 52.5%. % to 54.5 % of Fe, Ni, and Cr, and the non-magnetic melting region may include a region having a Cr content of 15% or more.

Further, in the method for manufacturing a stator for a motor according to an aspect of the present invention, a guide hole forming step (first manufacturing step) of forming a guide hole in the magnetic plate material is included before the demagnetization step, and the chromium The applying step applies the chromium with reference to the guide hole, the laser irradiation step applies laser with reference to the guide hole, and the processing step includes applying a laser to one of the non-magnetic regions with reference to the guide hole. You may make it process a part.

Further, in the method for manufacturing a motor stator according to an aspect of the present invention, the magnetic plate material contains 37.5% to 38.5% nickel, 7.5 to 8.5% chromium, and 7.5% to 8.5% iron. The plate material is an alloy plate material containing 52.5% to 54.5% of Fe, Ni, and Cr, and the non-magnetic region may include a region having a Cr content of 15% or more.

Further, in the method for manufacturing a stator for a motor according to an aspect of the present invention, the processing step includes processing by punching out a portion of the non-magnetic region, processing by cutting a portion of the non-magnetic region with a laser, and machining a part of the non-magnetic region by wire electric discharge.

In order to achieve the above object, a motor stator (stator 201) according to one aspect of the present invention is formed around a rotor hole (rotor housing hole 203) in a magnetic plate material, and the magnetic plate material is demagnetized by melting. a non-magnetic melting region (melting portion 401, narrow width portions 210, 211), the cross-sectional area of which decreases from one surface side of the magnetic plate toward the other surface side in the thickness direction; , provided.

Further, in the motor stator according to the aspect of the present invention, the circularity of the rotor hole may be 99.5% or more.

Further, in the motor stator according to one aspect of the present invention, the magnetic plate material has a nickel content of 37.5% to 38.5%, a chromium content of 7.5 to 8.5%, and an iron content of 52.5%. % to 54.5% of Fe, Ni, and Cr, and the non-magnetic melting region may include a region having a Cr content of 15% or more.

Further, in the motor stator according to one aspect of the present invention, the weight of chromium in the non-magnetic melting region may be 6% to 18% larger than the weight of chromium in the magnetic plate material excluding the non-magnetic melting region. good.

Further, in the motor stator according to one aspect of the present invention, the non-magnetic melting region is formed in a portion where the distance between the rotor hole and the outer edge of the magnetic plate is narrower than other portions. may

According to the present invention, thermal deformation due to laser irradiation can be reduced when forming a non-magnetic region.

1 is a block diagram showing a timepiece using a stepping motor and a timepiece movement according to this embodiment; FIG. 1 is a perspective view showing a schematic configuration example of a stepping motor according to an embodiment; FIG. It is a front schematic diagram of the stator which concerns on this embodiment. 1 is a schematic front view of a stepping motor according to an embodiment; FIG. It is a figure which shows an example of the manufacturing method of the stator which concerns on this embodiment. FIG. 4 is a top view showing the hoop material before pressing of the stator according to the present embodiment; FIG. 2 is a photograph showing an example of a cross-section of a permalloy hoop material after melting and diffusing chromium applied to the permalloy hoop material with a laser to increase the chromium content to 15% by weight or more in the present embodiment. FIG. 2 is a photograph showing an example of a cross-section of a permalloy hoop material after melting and diffusing chromium applied to the permalloy hoop material with a laser to increase the chromium content to 15% by weight or more in the present embodiment. FIG. 2 is a photograph showing an example of a cross-section of a permalloy hoop material after melting and diffusing chromium applied to the permalloy hoop material with a laser to increase the chromium content to 15% by weight or more in the present embodiment. FIG. 4 is a diagram showing an example of the result of EDS line analysis of the fusion zone according to the present embodiment; FIG. 2 is a ternary alloy phase diagram of Fe—Ni—Cr. FIG. 10 is a diagram showing examples of current waveforms of a one-piece stator and a two-piece stator, and examples of drive pulses during reverse rotation; FIGS. 13A and 13B are diagrams for explaining a method of manufacturing a stator in a comparative example. FIG. 13C is a view of the hoop material cut during the plating process in the comparative example. Fig. 3 shows a graph representing the change in coil current value versus time for three types of stators; FIG. 15A is a diagram showing a case where the rotor housing hole is not deformed. FIG. 15B is a diagram showing a case where the rotor housing hole is deformed. FIG. 15C is a diagram for explaining the horizontal axis of the stator and the stationary angle θ of the rotor. FIG. 5 is a diagram showing changes in torque with respect to rotor angle when the rotor housing hole is not deformed and when the rotor housing hole is deformed; FIG. 17A is a diagram showing changes in cogging torque with respect to the rotor angle when the rotor housing hole is not deformed. FIG. 17B is a diagram showing changes in stored energy with respect to the rotor angle when the rotor housing hole is not deformed. FIG. 17C is a diagram showing changes in integral torque with respect to the rotor angle when the rotor housing hole is not deformed. FIG. 18A is a diagram showing changes in cogging torque with respect to the rotor angle when the rotor housing hole 203 is deformed. FIG. 18B is a diagram showing changes in stored energy with respect to the rotor angle when the rotor housing hole 203 is deformed. FIG. 18C is a diagram showing changes in integral torque with respect to the rotor angle when the rotor housing hole 203 is deformed. It is a figure which shows the modification of chromium application|coating which concerns on this embodiment. FIG. 20(A) is a perspective view of a hoop material after forming a chrome layer in a modified example. FIG. 20(B) is a cross-sectional view of the hoop material after the chromium layer is formed along line Y-Y' of FIG. 20(A). It is a front view before punching out the stator for two coil motors in a modification from a hoop material. It is a front view before a press of the stator for two coil motors in a modification. It is a figure which shows the example which performs the 3rd manufacturing process in the manufacturing method of the stator which concerns on this embodiment by laser cutting. It is a figure which shows the example which performs the 3rd manufacturing process by wire electric discharge machining in the manufacturing method of the stator which concerns on this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the drawings used for the following description, the scale of each member is appropriately changed so that each member has a recognizable size.

FIG. 1 is a block diagram showing a timepiece 1 using a stepping motor and a timepiece movement according to this embodiment. In this embodiment, an analog electronic timepiece will be exemplified and explained as an example of the timepiece.
As shown in FIG. 1, the clock 1 includes a battery 2, an oscillator circuit 3, a frequency divider circuit 4, a control circuit 5, a pulse drive circuit 6, a stepping motor 7, and an analog clock section 8.
The analog clock section 8 also includes a train wheel 11, an hour hand 12, a minute hand 13, a second hand 14, a calendar display section 15, a clock case 81, and a clock movement 82 (hereinafter referred to as movement 82). In this embodiment, when one of the hour hand 12, the minute hand 13, the second hand 14, and the calendar display portion 15 is not specified, the hand 16 is used.

The oscillation circuit 3 , the frequency dividing circuit 4 , the control circuit 5 , the pulse drive circuit 6 , the stepping motor 7 , and the train wheel 11 are components of the movement 82 .
In general, the mechanical body of the timepiece, which includes devices such as the time base of the timepiece 1, is called a movement.
The electronic type is sometimes called a module. When the watch is completed, the movement is fitted with, for example, a dial and pointers, and housed in a watch case.

The battery 2 is, for example, a lithium battery, a so-called button battery. Note that the battery 2 may be a solar battery and a storage battery that stores electric power generated by the solar battery. Battery 2 supplies power to control circuit 5 .

The oscillator circuit 3 is a passive element that uses, for example, the piezoelectric phenomenon of crystal and is used to oscillate a predetermined frequency from its mechanical resonance. Here, the predetermined frequency is, for example, 32 [kHz].
The frequency dividing circuit 4 divides the predetermined frequency signal output from the oscillation circuit 3 into a desired frequency, and outputs the frequency-divided signal to the control circuit 5 .

The control circuit 5 measures time using the frequency-divided signal output from the frequency dividing circuit 4, and generates a driving pulse based on the time-lapsed result. Note that the control circuit 5 generates a drive pulse for forward rotation when the hands 16 are operated in the forward rotation direction. The control circuit 5 generates a drive pulse for reverse rotation when the hands 16 are moved in the reverse direction. The control circuit 5 outputs the generated drive pulse to the pulse drive circuit 6 .

A pulse drive circuit 6 generates a drive pulse for each pointer according to a drive instruction output by the control circuit 5 . The pulse drive circuit 6 outputs the generated drive pulse to the stepping motor 7 .

The stepping motor 7 moves the hands 16 (the hour hand 12, the minute hand 13, the second hand 14, and the calendar display portion 15) according to the driving pulses output by the pulse driving circuit 6. FIG. In the example shown in FIG. 1, for example, one stepping motor 7 is provided for each of the hour hand 12, minute hand 13, second hand 14, and calendar display section 15. FIG.

The hour hand 12 , minute hand 13 , second hand 14 and calendar display section 15 are each moved by a stepping motor 7 .
The hour hand 12 rotates once every 12 hours as the pulse driving circuit 6 drives the stepping motor 7 . The minute hand 13 rotates once in 60 minutes by driving the stepping motor 7 by the pulse driving circuit 6 . The pulse drive circuit 6 drives the stepping motor 7 to rotate the second hand 14 once every 60 seconds. The calendar display unit 15 is, for example, a pointer for displaying the date, and rotates once every 24 hours as the stepping motor 7 is driven by the pulse driving circuit 6 .

Next, a schematic configuration example of the stepping motor 7 according to this embodiment will be described.
FIG. 2 is a perspective view showing a schematic configuration example of the stepping motor 7 according to this embodiment. As shown in FIG. 2, the stepping motor 7 includes a stator 201, a rotor 202, a magnetic core 208, coils 209, and screws 220.
The stator 201 is formed with a rotor housing hole 203, screw holes 218a, and screw holes 218b.
The rotor 202 is rotatably arranged in the rotor housing hole 203 .
A coil 209 is wound around a magnetic core.
When the stepping motor 7 is used in an analog electronic timepiece, the stator 201 and the magnetic core 208 are fixed to the main plate (not shown) of the movement 82 by screws 220 and joined together.

Here, the stator 201 will be explained using FIG.
FIG. 3 is a schematic front view of the stator 201 according to this embodiment. In FIG. 3, the longitudinal direction of the stator 7 is the y-axis direction, and the lateral direction is the x-axis direction. The stator 201 shown in FIG. 3 is manufactured by a method for manufacturing a motor stator, which will be described later. As shown in FIG. 3 , notches 204 and 205 are formed in the rotor housing hole 203 . Further, narrow width portions 210 and 211 are formed around the rotor housing hole 203 in the stator 201 . The stator 201 is made of, for example, a Fe—Ni (iron-nickel) magnetic plate material. Also, the narrow portions 210 and 211 are non-magnetic regions.

When the stepping motor 7 is used in a timepiece, an example of each size of the stator 7 will be explained.
The hole diameter of the rotor housing hole 203 is approximately 1.5 to 2 mm. The width of the narrowest portion of the narrow portions 210 and 211 is approximately 0.1 mm. The thickness of the stator 7 is approximately 0.5 mm±0.1 mm. The longitudinal length is approximately 10 mm.

Next, the stepping motor 7 according to this embodiment will be described in detail with reference to FIG.
FIG. 4 is a schematic front view of the stepping motor 7 according to this embodiment.
A stepping motor 7 shown in FIG.

The stator 201 is provided with a magnetic path R around the rotor housing hole 203 . The rotor 202 is a two-pole rotor rotatably arranged in the rotor housing hole 203 . Magnetic core 208 is joined to stator 201 . Coil 209 is wound around magnetic core 208 .

Note that the narrow portions 210 and 211 are provided at portions that do not interfere with the cutout portions 204 and 205 provided in the rotor housing hole 203 in order to secure the stable position of the rotor 202 . The coil 209 has a first terminal OUT1 and a second terminal OUT2.

The rotor housing hole 203 has a circular hole shape in which a plurality of (two in the example of FIG. 4) half-moon shaped cutouts (inner notches) 204 and 205 are integrally formed in opposing portions of the circular through hole. It is configured. These notch portions 204 and 205 are configured as positioning portions for determining the stop position or stationary stable position of the rotor 202 . For example, the notch (inner notch) 204 has the effect of stabilizing the position of the rotor by lowering its potential energy when the rotor reaches a predetermined position.

The rotor 202 is magnetized with two poles (S pole and N pole).
When the coil 209 is not energized, the rotor 202 is at a position corresponding to the positioning portion as shown in FIG. and is stably stopped (stationary) at a position (angle θ ₀ position) perpendicular to .

Narrow width portions 210 and 211 of non-magnetic regions are formed in a part (two places in the example of FIG. 4) of the magnetic path R provided around the rotor housing hole 203 . Here, the cross-sectional width of the narrow portion of the stator 201 is defined as a cross-sectional width t, and the width along the magnetic path is defined as a gap width w. The narrow portions 210 and 211 are formed in regions defined by the cross-sectional width t and the gap width w.
In the following description, in the stator 201, the outer circumference of the narrow portion 211 is a point a ₁ , the inside of the narrow portion 211 is a point b ₁ , the vicinity of the narrow portion 211 and between the outer circumference and the inner circumference of the magnetic path R is a point. Define c.
A method of manufacturing stator 201 will be described later.

Next, the operation of the stepping motor 7 according to this embodiment will be described with reference to FIG.
First, a drive pulse signal is supplied from the pulse drive circuit 6 between the terminals OUT1 and OUT2 of the coil 209 (for example, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative), and the current i is generated in the direction of the arrow in FIG. , magnetic flux is generated in the direction of the dashed arrow in the stator 201 .

In this embodiment, narrow width portions 210 and 211, which are non-magnetic regions, are formed, and the magnetic resistance of these regions is increased. Therefore, it is not necessary to magnetically saturate the region corresponding to the conventional “narrow width portion”, and leakage magnetic flux can be easily ensured. rotates 180 degrees in the direction of the arrow in FIG. 4, and the magnetic pole axis stably stops (stands still) at the angle θ ₁ position.
Note that the rotation direction (counterclockwise direction in FIG. 4) for performing normal operation (hand movement operation since each embodiment of the present invention is an analog electronic timepiece) by rotating the stepping motor 7 is the positive direction. and the reverse direction (clockwise direction) is defined as the reverse direction.

Next, from the pulse driving circuit 6, drive pulses of opposite polarity are supplied to the terminals OUT1 and OUT2 of the coil 209 (the first terminal OUT1 side is negative and the second terminal OUT2 side is the positive electrode), and when a current is passed in the direction opposite to the arrow in FIG.
After that, as in the case described above, since the narrow width portions 210 and 211 which are non-magnetic regions are formed, leakage magnetic flux can be easily secured, and the interaction between the magnetic poles generated in the stator 201 and the magnetic poles of the rotor 202 causes , the rotor 202 rotates 180 degrees in the same direction (positive direction) as above, and the magnetic pole axis stably stops (stands still) at the angle θ ₀ position.

Thereafter, by supplying signals of different polarities (alternating signals) to the coil 209 in this way, the above operation is repeated, and the rotor 202 can be continuously rotated in increments of 180 degrees in the direction of the arrow. .

As described above, since the narrow width portions 210 and 211, which are non-magnetic regions, are formed in part of the magnetic path around the rotor housing hole 203, the magnetic flux consumed in this region can be greatly reduced, and the rotor 202 It is possible to efficiently secure the leakage magnetic flux that drives the .
In addition, by forming narrow width portions 210 and 211, which are non-magnetic regions, in places conventionally referred to as “narrow width portions” to reduce magnetic permeability, the magnetic flux emitted from the rotor 202 itself can also consumption will be curtailed. As a result, the loss of magnetic potential can be prevented, and the holding force for magnetically stopping (stationary) and holding the rotor 202 can be increased.

In addition, after saturating the portion that was conventionally referred to as the “narrow width portion” with the magnetic flux on the OUT1 side (negative electrode) and rotating it on the OUT2 side (positive electrode), it occurs at the OUT1 side (negative electrode). It was necessary to cancel the residual magnetic flux. However, according to this embodiment, since the residual magnetic flux in the region is greatly reduced, the time required for canceling the residual magnetic flux is eliminated, and the time required for the rotation to converge can be shortened. Therefore, according to the present embodiment, it is possible to maintain operational stability during high-speed hand movement, and increase the drive frequency. A driving pulse for driving the stepping motor 7 will be described later.

<Description of manufacturing method>
Next, an example of a method for manufacturing stator 201 will be described with reference to FIG.
FIG. 5 is a diagram showing an example of a method of manufacturing the stator 201 according to this embodiment.

(First manufacturing process 1st press (creation of guide holes))
In the first manufacturing process, the manufacturing system 300 has a press device 302 . Reference numeral 301 denotes a state in which the hoop material 310 before pressing is wound. Reference numeral 303 denotes a state in which the pressed hoop material is wound up. Reference numeral 310 is a top view of the hoop material after pressing. In FIG. 5, the longitudinal direction of the hoop material is defined as the x-axis direction, and the lateral direction thereof is defined as the y-axis direction. Moreover, the width of the hoop material in the lateral direction is, for example, 16.5 mm.

A press device 302 forms guide holes 312 and 313 for positioning in the upper and lower positions in the magnetic material (38 permalloy, etc.) in the form of a hoop material. After pressing, the manufacturing system 300 winds up the pressed hoop material 303 .

(Second manufacturing process non-magnetic region creation)
In the second manufacturing process, the manufacturing system 300 includes a paste application device 322 that applies chromium (Cr) paste, a drying device 323 , a laser irradiation device 324 and a cleaning device 325 . Reference numeral 321 denotes a state in which the hoop material after being pressed in the first manufacturing process is wound. Reference numeral 326 is the wound state of the hoop material 310 after the non-magnetic regions have been created.

The paste application device 322 applies chromium paste to desired positions in the y-axis direction on the hoop material. The paste applicator 322, for example, mixes chromium with a binder to form a paste and dispenses it. That is, the paste application device 322 is a dispenser. It should be noted that the desired position in the y-axis direction is the region where the narrow width portions 210 and 211, which are the non-magnetic regions, of the stator 201 shown in FIG. 3 are to be formed. Note that the paste applying device 322 applies the chromium paste to a desired position based on the position of the guide hole. The coating thickness of Cr is, for example, 150 to 200 [microns].
Subsequently, a drying device 323 dries the pasted chromium.

Subsequently, the laser irradiator 324 irradiates the area (reference g331) where the chromium is pasted with a laser. The laser is preferably a fiber laser with a deep discharge depth. As a result, the applied chromium melts into the base material (permalloy material). Then, the applied chromium and the chromium inside the permalloy material diffuse and melt, forming a region where the chromium weight ratio is 15% or more. Note that the region where the chromium paste is applied by the laser irradiation becomes higher than the melting point of Cr and higher than 1900 degrees. Also, the aperture on the laser incident side is about 0.3 to 0.5 mm. Also, the laser irradiation device 324 irradiates the laser at intervals of, for example, 25 [microns] in the x-axis direction. As a result, heat applied to the base material (hoop material) due to laser irradiation can be reduced.

Subsequently, the cleaning device 325 cleans the applied chromium using a solvent to remove unnecessary portions. Symbol g310A is a top view of the hoop material after laser irradiation and cleaning. In code g310A, code g331 indicates a non-magnetic region. The width of the non-magnetic region in the y-axis direction is approximately 0.3 to 0.5 mm. In this way, by the second manufacturing process, linear non-magnetic regions continuous in the x-axis direction are formed at predetermined positions in the y-axis direction on the hoop material. Also, the time required for cleaning is, for example, 5 minutes.
After cleaning, the manufacturing system 300 winds up the hoop material after forming the non-magnetic regions, as at 326 .

(Third manufacturing process 2nd press (finishing))
In the third manufacturing process, the manufacturing system 300 includes a press device 342 as a finishing device. Reference numeral 341 denotes a state in which the hoop material after the second manufacturing process is wound. Reference numeral 343 denotes a state in which the pressed hoop material is wound up.
The press device 342 presses the positions of the guide holes 312 and 313 as a reference so that the narrow portions 210 and 211 of the stator 201 become the narrow portions 210 and 211 of the stator 201 as shown in FIG. I do. FIG. 6 is a top view showing hoop material 310A before pressing of stator 201 according to the present embodiment. Note that the stator 201' is a stator before the fourth manufacturing process. In FIG. 6, reference numeral 201'' indicates a position where the stator 201' is pressed. The punching is performed by punching a part of the non-magnetic region 331 to form a shape surrounding the rotor 202 for the stepping motor 7 . That is, the rotor receiving hole 203 is also formed at the same time by the third manufacturing process.
This completes the outer shape of the stator 201' in which the chromium weight ratio differs between the narrow width portion and the other portions.

(Fourth manufacturing process magnetic annealing)
In the fourth manufacturing process, the manufacturing system 300 has an annealing furnace 351 .
The annealing furnace 351 performs high temperature annealing (annealing) on the stator 201'. As a result, the residual stress due to the press working in the third manufacturing process is removed/relaxed.

Manufacturing system 300 manufactures stator 201 shown in FIG. 3 through the first to fourth manufacturing processes described above.

According to the stator 201 manufactured by the manufacturing process described above, it is possible to reduce thermal deformation due to laser irradiation during the formation of the non-magnetic regions.

<Explanation of a photograph example of the cross section of the hoop material after laser irradiation>
Next, the chromium coated on one side of the permalloy hoop material is irradiated with a laser, and melted and diffused by the laser to increase the chromium content to 15% by weight or more. It is shown in FIG. 7 to 9 are photographs showing examples of cross sections of the permalloy hoop material after the chromium applied to the permalloy hoop material is melted and diffused with a laser to increase the chromium content to 15% by weight or more in the present embodiment. .

7 to 9, the vertical direction (z-axis direction) is the thickness direction of the hoop material. Also, the laser is irradiated from the surface (upper surface) coated with chromium. The thickness of the hoop material is, for example, 0.5 mm±0.1 mm. 7 to 9, reference numeral 401 denotes a melted portion melted by laser irradiation.

FIG. 7 shows an example in which the fusion zone 401 penetrates from the upper surface to the lower surface. FIG. 8 shows an example in which the fusion zone 401 reaches the bottom surface. FIG. 9 shows an example in which the fusion zone 401 does not reach the bottom surface.
7 to 9, symbols L1, L11, and L21 indicate the width of the melted portion on the laser irradiation side. Reference numerals L2, L12, and L22 indicate the width of the fusion zone at the half thickness position of the hoop material.

As shown in FIGS. 7 to 9, when manufactured by the manufacturing method of this embodiment, the width of the melted portion on the laser incident side is wider than the width of the melted portion other than the surface in the thickness direction of the hoop material. In addition, the width of the fusion zone is narrowed from one surface side (upper side) of the hoop material, which is a magnetic plate material, toward the other surface side (lower side) in the thickness direction, and the cross-sectional area is reduced.
In any of the examples shown in FIGS. 7 to 9, the mass % of Cr in the fusion zone is 15% or more, and the fusion zone is formed as a non-magnetic region.

<Description of EDS line analysis results>
Next, the result of EDS line analysis of the fusion zone manufactured by the manufacturing method of the present embodiment will be described.
First, an outline of EDS (Energy Dispersive X-ray Spectroscopy) line analysis will be described.
When X-rays enter the device, electric charges are generated in proportion to the energy of the X-rays. An analyzer that performs EDS line analysis converts this charge into a current proportional to the amount of charge by accumulating it in, for example, the gate electrode of a field effect transistor. Then, the analyzer converts the current change for each X-ray into pulses, and measures the pulse number (X-ray count number) for each wave height with a multi-wave height analyzer. Furthermore, the analysis apparatus converts the measurement results into a spectrum with the X-ray energy value (keV) on the horizontal axis and the X-ray count number on the vertical axis (see Reference 1, for example).

Reference 1; "What is EDS analysis? How can it be analyzed well? (Basics of EDS analysis)", Iwao Yamazaki, Bruker AXS Co., Ltd., 2014, https://www .bruker.com/fileadmin/user_upload/8-PDF-Docs/X-rayDiffraction_ElementalAnalysis/Microanalysis_EBSD/Webinars/Bruker_Japanese_Webinar_2014-11-25_EDS_Feature_Analysis.pdf#search=%27%EF%BC%A5%EF%BC%A4%EF% BC%B3%E3%83%A9%E3%82%A4%E3%83%B3%E5%88%86%E6%9E%90%27 (internet search 2017.9.10)

An analysis device and analysis conditions will be explained.
Observed portions of the narrow portions 210 and 211 were cross-section polisher (CP) processed using IB-09020CP (trade name) manufactured by JEOL Ltd. The acceleration voltage was set to 7 kV.
A field emission scanning electron microscope (FE-SEM) (trade name: JSM-7800F, manufactured by JEOL Ltd.) was used as the scanning electron microscope.

After resin embedding and polishing, the sample was subjected to ion milling using IB-9020CP manufactured by JEOL.
The state of the sample at the time of measurement is a cross section processed by ion milling {Ar (argon) ions, acceleration 7 kV}.
The measurement environment was a vacuum with a degree of vacuum of 10 ^-4 to 10 ^-5 Pa.
The EDS line analysis was performed using NORAN SYSTEM7 (trade name) Ver3 manufactured by Thermo Fisher Scientific under the condition of an applied voltage of 15 kV.

Next, an example of the result of EDS line analysis of the fusion zone is shown.
FIG. 10 is a diagram showing an example of the result of EDS line analysis of the fusion zone according to the present embodiment.
In FIG. 10, the diagram indicated by symbol g1 is a diagram showing the fusion zone on which the EDS line analysis was performed. The y-axis direction is the longitudinal direction of the stator 201, as shown in FIG. Further, the figure indicated by symbol g1 is the result of imaging the dissolved portion with a reflection microscope, and the magnification is 120 times.
Also, the figure indicated by symbol g2 is a graph showing the result of the line analysis. The horizontal axis is position [microns] and the vertical axis is mass [%]. Further, the sign g21 represents the change in mass [%] with respect to the distance of Cr (chromium), the sign g22 represents the change in mass [%] with respect to the distance of Fe (iron), and the sign g23 represents Ni (nickel). represents the change in mass [%] with respect to the distance of A region surrounded by a dashed line g24 is a region where the mass of Cr changes.

In FIG. 10, the fusion zone is a section from about 140 [microns] to 400 [microns]. In this interval the mass of Cr is about 20-28%. In this region, since the mass of Cr is 15% by mass or more, it is paramagnetic at room temperature, and point b1 in FIG. ₄ is this region. Note that paramagnetism is magnetism that does not have magnetization when there is no external magnetic field and magnetizes in that direction when a magnetic field is applied. Moreover, the state of paramagnetism at normal temperature means the state of non-magnetism. The mass % of Fe in this region is about 41-51%, and the mass % of Ni is about 30-38%.

Here, an Fe--Ni--Cr alloy, which is 38 permalloy, is ferromagnetic at room temperature when it contains 54% by mass of Fe, 38% by mass of Ni, and 8% by mass of Cr. Note that ferromagnetism is the magnetism of a substance that has a magnetic moment.
In FIG. 10, the regions where the mass of Cr is about 8% are the positions up to about 140 [microns] from the outer end side and the positions after 400 [microns]. This region is a ferromagnetic region because the mass of Cr is about 7-8% by mass, which is equivalent to the mass of the Cr component in 38 permalloy, and _points b1 and c in FIG. 4 are this region.

As described above, the stator 201 manufactured by the manufacturing process of the present embodiment has a paramagnetic region having a Cr mass of 15% by mass or more and a ferromagnetic region having a Cr mass of 7 to 8% by mass. , and a region where the mass of Cr varies greatly (the region surrounded by the broken line g24 in FIG. 10). Thus, the stator 201 manufactured by the manufacturing process of this embodiment has a non-magnetic region (point b ₁ in FIG. 4). Further, in the stator 201, the difference between the Cr content X% of the fusion zone and the Cr content Y% of the other regions is 6% or more (XY≧6), and the Cr weight of the fusion zone is It is more than the base material.
Also, as shown in FIG. 10, the weight of chromium in the non-magnetic melting region is 6% to 18% larger than the 8% weight of chromium in the magnetic plate excluding the non-magnetic melting region.

In addition, in the stepping motor 7 according to the present embodiment, the stator 201 is made of an Fe--Ni alloy, but it is preferable to use an Fe--Ni alloy with a high magnetic permeability. For example, the 38 permalloy mentioned above can be exemplified. From the phase diagram of FIG. 11, the Curie temperature of Fe-38%Ni-8%Cr is 500 K or more (point X), but when Cr is 15% by mass or more, the Curie temperature becomes 300 K and the austenite phase occurs at room temperature. becomes (point X'). FIG. 11 is a ternary alloy phase diagram of Fe—Ni—Cr. In other words, the non-magnetic state of the stator 201 can be ensured when the Cr content is 15% by mass or more around the normal temperature at which the stepping motor 7 is required to be driven. FIG. 11 is a phase diagram quoted from Item 188 of Ternary alloys Between Fe, Co or Ni and Ti, V, Cr or Mn (Landolt-Bornstein new Series III/32A).

<Current Flowing through Coil 209 of Stepping Motor 7>
Next, the current flowing through the coil 209 of the stepping motor 7 will be described with reference to FIG.
Fig. 1 shows an example of changes in current I with respect to time t in a general integrated stator (also called a one-body stator) in a stepping motor and changes in current with time in a general two-body stator (also called a two-body stator). 12 for explanation. 12A and 12B are diagrams showing examples of current waveforms of the one-piece stator and the two-piece stator, and examples of drive pulses during reverse rotation. Waveform g301 is the current waveform of the current change with respect to time in the integrated stator. A waveform g321 is a current waveform of a change in current with respect to time in the two-piece stator. In the waveforms g301 and g321, the horizontal axis is time, and the vertical axis is the current flowing through the coil. The configuration of the stepping motor having the integrated stator is the same as that of the stepping motor 7 shown in FIG.

As shown in waveform g301, waveform g301 has a plurality of different slope periods, such as the regions enclosed by dashed lines g302-g304. Hereinafter, in the present embodiment, the area surrounded by the dashed line g302 is called the first slope period, the area surrounded by the dashed line g303 is called the second slope period, and the area surrounded by the dashed line g304 is called the third slope period.

The first ramp period is a period dependent on the self-inductance L of the coil of the stepping motor, and is a period during which the magnetic flux generated from the coil flows through the stator.
The second tilt period is a period during which the magnetic flux generated by the coil during the first tilt period flows to the narrow width portion because the magnetic flux flows in the portion with low magnetic resistance. When a predetermined current flows, the magnetic flux in the narrow portion is saturated. In other words, the second tilt period is a period during which the magnetic flux in the narrow portion is saturated.
The third tilt period is a state in which the magnetic flux leaks into the rotor housing hole after the magnetic flux in the narrow portion is saturated during the second tilt period. In other words, the third tilt period is the period during which the rotor begins to move.
In a stepping motor having an integrated stator, the repulsive force of the magnetic flux acts on the rotor during the third tilt period, and the rotor starts to rotate.

A stepping motor having a two-piece stator has, as shown in waveform g321, a first slope period surrounded by a dashed line g322 and a third slope period surrounded by a dashed line g323. That is, a stepping motor with a two-piece stator does not have a second tilt period. That is, the two-piece stator does not require a period of magnetic saturation.

Next, examples of drive pulses for reverse rotation in a stepping motor having a one-piece stator and a stepping motor having a two-piece stator will be described.
In FIG. 12, waveforms g311 and g312 are drive pulse waveforms for reverse rotation in a stepping motor having an integrated stator. Waveforms g331 and g332 are drive pulse waveforms for reverse rotation of a stepping motor having a two-piece stator. In waveforms g311, g312, g331 and g332, the horizontal axis is time and the vertical axis is signal level. Out1 and out2 are terminals at both ends of the coil of the stepping motor. Vdd is the power supply voltage of a drive circuit that drives, for example, a stepping motor, and Vss is 0 V or a reference voltage.

As shown in waveforms g311 and g312, the drive pulse of the stepping motor having an integral stator is first of all, during the period from time t1 to t2, the width Pe is input to out1 of the coil. During a period of time t3 to t4 after a predetermined period of time Ps from time t2, a drive pulse having a width of P1 is input to the coil out1, thereby driving the rotor to slightly move in the forward direction. Note that the period Ps is a waiting period during which the rotor returns to its original position after the driving pulse of the period Pe is input. After that, during the period from time t4 to time t5, by inputting a drive pulse having a width P2 to the out2 of the coil, the rotor is driven so as to slightly move in the reverse direction. After that, during the period from time t5 to time t6, the rotor is driven to move in the reverse direction by inputting a drive pulse with a width P3 to the out1 of the coil.

If the driving pulse of width Pe is not input to coil out1 and the driving pulse of width P1 is input at time t3, the residual magnetic flux remains and the operation of the rotor becomes unstable. In this way, in a stepping motor having a general integrated stator, during reverse rotation, the period of the driving pulse with the width Pe for canceling the residual magnetic flux and the period Ps, which is the waiting period, move the pointer by one step. A frame f, which is a period for

Here, the period Ps is, for example, 5 to 6 [ms], and the total of the width P1, the width P2, and the width P3 is, for example, 10 to 15 [ms]. Also, the period until the rotor returns to the stationary position after being driven by the driving pulse of width P3 is, for example, about 5 [ms], like the standby time. In this case, the total of one frame f is 20 (=5+10+5) to 26 (=6+15+5) [ms]. For example, when one frame is 32 [Hz], it is 31.25 [ms]. For this reason, in a stepping motor having an integrated stator, one frame is driven at a cycle of 32 [Hz] when performing reverse rotation. Since the period of the driving pulse with the width Pe and the period Ps were necessary for the reverse rotation, there was a technical barrier that the frequency during the reverse rotation could not be set to 32 [Hz] or more.

On the other hand, when a stepping motor having a two-piece stator is reversed, one frame f is defined by widths P1, P2, P3, and the period until the rotor returns to the stationary position, as shown by waveforms g331 and g332. It is the total, for example, 20 (=15+5) [ms]. Therefore, a stepping motor having a two-piece stator can shorten one frame during reverse rotation, for example, 50 [Hz], compared to a stepping motor having an integral stator.

Although the two-piece stator has such an effect, the stator, which is completely separated and divided as a mechanical structure, has the problem that the static position is not stable due to positional deviation during assembly. In motors, it has been difficult to use a two-piece stator. In addition, in the stator of such a mechanically separated structure, as described above, the stator is divided into two parts by machining and then joined by welding. was likely to occur. For this reason, the two-body stator also has a problem that an error occurs in the distance between the rotor and the stator.

Here, a comparative example for solving such problems of the two-piece stator will be described.
FIGS. 13A and 13B are diagrams for explaining a method of manufacturing a stator in a comparative example. FIG. 13C is a view of the hoop material cut during the plating process in the comparative example.

In a comparative example (see Japanese Patent Application Laid-Open No. 2016-136830), first, an Fe—Ni alloy plate is subjected to machining such as punching (pressing) to form the rotor housing hole 203 and the periphery of the rotor housing hole 203. forming a stator blank having a magnetic path R disposed thereon; Cutouts (inner notches) 204 and 205 can also be formed in this step. It should be noted that the stator material 201a is preferably made of an Fe--Ni alloy having a high magnetic permeability, such as Fe-38% or Ni-8% Cr (so-called 38 permalloy).

Next, a Cr material for melting and diffusing is disposed on at least a portion of the stator material 201a, and a laser is irradiated to the Cr material to melt and diffuse the Cr material inside the magnetic path R, thereby forming the narrow portions 210 and 211. Form.
Specifically, for example, a paste containing powdered metallic chromium may be applied to at least a portion of the magnetic path, and the paste may be melted and diffused by irradiating the paste with a laser. Alternatively, a chromium plating layer may be formed in advance on the surface of the stator material 201a, and the chromium plating layer formed on at least a part of the magnetic path R may be melted and diffused by irradiating the chromium plating layer with a laser. good. In the case of plating, the mass ratio of Cr does not exceed 80% in consideration of the possibility of covering the stator base material. Alternatively, it may be powder instead of paste. When the plating process is performed, as shown in FIG. 13(C), the hoop material 216 is placed in a plating tank with a portion (215a, 215b) of the stator material 201a connected to the hoop material 216. Cut into thin strips. Then, a mask 217 is applied to portions not to be plated.

As shown in FIGS. 13(A) and 13(B), the narrow portions 210 and 211 are formed with the above-described paste or chromium plating layer on cutout portions (outer notches) 213 and 214 .
Next, after forming the narrow portions 210 and 211 (Cr diffusion regions) to obtain the stator material 201a, the rotor 202 is arranged in the rotor housing hole 203, and the magnetic core is fixed by the stator material 201a and arbitrary fixing means. is fixed, and a coil is wound around this magnetic core to manufacture a stepping motor.

FIG. 14 shows a graph representing changes in coil current values versus time for three types of stators. In other words, FIG. 14 is the saturation characteristic. In FIG. 14, the vertical axis is the current value (mA) of the coil 209, and the horizontal axis is time (msec). This graph was obtained by removing the rotor in order to confirm the saturation state only with the magnetic flux generated from the coil, excluding the influence of the magnetic flux generated from the magnet of the rotor. Here, the three types of stators are, for example, a first stator in which Cr is diffused in the narrow portions 210 and 211 in an inert helium atmosphere at 1200° C. for one hour, and a first stator in which Cr is diffused in the narrow width portions 210 and 211 in an inert helium gas atmosphere. C. for 24 hours, Cr is diffused into the narrow portions 210 and 211, and the third stator is a base material plated with Cr and not diffused at 1200.degree.
Waveform g401 shows the change in current over time for the first stator. Waveform g402 shows the change in current over time for the second stator. Waveform g403 shows the change in current over time for the third stator.

As shown by waveform g403, the third stator has three tilt periods, similar to the general integrated stator shown by waveform g301 in FIG. For example, the period from 0 to about 0.05 [ms] is the first slope period, the period from about 0.05 to 0.7 [ms] is the second slope period, and the time is about 0.7 to 1.7 [ms] is the third slope period.
Also, the first stator waveform g401 in which Cr is diffused for one hour has three slope periods. For example, the period from 0 to about 0.05 [ms] is the first slope period, the period from about 0.05 to 0.5 [ms] is the second slope period, and the time is about 0 A period of 0.5 to 1.2 [ms] is the third slope period.
Furthermore, the waveform g402 of the second stator in which Cr is diffused for 24 hours has two tilt periods like the general two-piece stator shown in the waveform g321 of FIG. For example, the period from 0 to about 0.05 [ms] is the first slope period, and the period from about 0.05 to 0.5 [ms] is the third slope period.
As shown in FIG. 14, the saturation characteristic of the stator having Cr diffused into the narrow width portions 210 and 211 can be improved as compared with the third stator in which Cr is not diffused into the narrow width portions 210 and 211. can.
It should be noted that each tilt area and the time and width of each tilt area described above are examples for explanation.

In the comparative example, the above-described paste or chromium plating layer was formed on cutouts (outer notches) 213 and 214 of a component punched into the shape of a stator. Further, in the comparative example, as shown in FIG. 13, the Cr paste was applied from the thickness direction of the plate, and after the application, the plate was irradiated with a laser for laser melting. Here, a plating time of about 2 hours was required to obtain a plating thickness of 20 [microns]. When such melting is performed, if the hoop material is pressed for the first time so that part of the stator is not cut, the size of the hoop material that fits in the plating bath (for example, the length in the longitudinal direction is 90 mm) ), it was necessary to cut and process the hoop material. Therefore, in the comparative example, it was difficult to manufacture a stator using a long hoop material. In addition, the required amount of plating had to be applied to both sides of the plate to allow the laser to penetrate. In addition, when plating is performed as in the comparative example, it takes a long time to remove the Cr plating adhered to unnecessary portions in the plating bath because the step of "peeling the plating" is required. Furthermore, in the comparative example, since the narrow width portions 210 and 211 are irradiated with the laser, there is concern that the rotor housing hole 203 may be deformed by heat.

On the other hand, in this embodiment, before the stator 201 is punched, Cr paste is applied to desired positions with reference to the guide holes in the thickness direction of the plate pressure. In this embodiment, the laser is subsequently irradiated from the plate thickness direction. In this embodiment, the stator 201 is manufactured by punching using the guide hole as a reference.
The stator 201 manufactured by the manufacturing method of the present embodiment can improve the saturation characteristic similarly to the second stator in which Cr is diffused into the narrow width portions 210 and 211 for 24 hours shown in FIG. .

Thus, according to the present embodiment, the stator 201 is punched after the laser is irradiated to form the melted portion, so deformation of the stator 201 during manufacturing can be prevented. As a result, according to this embodiment, the shape of the stator 201 can be produced with stable accuracy. According to the present embodiment, since Cr is applied in the thickness direction of the stator 201 to form the fusion zone, the cross-sectional area of the fusion zone increases as shown in FIGS. It can be increased to prevent deformation due to handling. Moreover, according to this embodiment, after the Cr paste is melted by the laser, the Cr paste adhering to unnecessary portions can be easily removed with a solvent. Further, according to the present embodiment, the amount of chromium necessary for demagnetization can be supplied from one surface.

Furthermore, according to the present embodiment, since the magnetically two-piece stator is used, it is possible to reduce the influence of the residual magnetic flux generated in the narrow portion caused by the reverse rotation of the stator in a general integrated stator. can be done. Thus, according to this embodiment, the width P3 shown in FIG. 12 can be made shorter than in the conventional art. By suppressing the total of the width P1, width P2, width P3, and the rest period after the width P3 to, for example, 15 [ms], the period of one frame can be reduced to 64 [Hz], that is, double that of the conventional one. At speed, the needle can be rotated backwards. That is, according to this embodiment, one frame when rotating the needle in reverse using a stepping motor using an integral stator is exceeded by 64 [Hz] beyond the technical barrier of 32 [Hz]. fast forward can be realized.

<Comparison between when the rotor housing hole of the stator is not deformed and when it is deformed>
Next, a case where the rotor housing hole of the stator is deformed and a case where it is not deformed will be described with reference to FIGS. 15 to 18. FIG.
FIG. 15A is a diagram showing a case where the rotor housing hole is not deformed. FIG. 15B is a diagram showing a case where the rotor housing hole is deformed. FIG. 15C is a diagram for explaining the horizontal axis of the stator and the stationary angle θ of the rotor.

As shown in FIG. 15A, when the rotor housing hole 203 is not deformed, the hole diameter is approximately a perfect circle with a diameter of 1.8 mm. As shown in FIG. 15B, when the rotor housing hole 203a is deformed, the hole diameter is approximately 1.8 mm in width and approximately 1.7 mm in length. In FIG. 15(C), a dashed line 218 in the horizontal direction (y-axis direction) represents the stator horizontal axis, and the angle θ is the orientation angle of the magnetic pole axes with respect to the stator horizontal axis 218 when not excited. In the following description, this angle θ will be referred to as the rotor stationary angle θ.

FIG. 16 is a diagram showing changes in torque with respect to the rotor angle when the rotor housing hole is not deformed and when the rotor housing hole is deformed. In FIG. 16, the horizontal axis is the rotor angle [deg] and the vertical axis is the torque [μNm]. A waveform g31 indicates a change when the rotor housing hole 203 is not deformed. A waveform g32 indicates a change when the rotor housing hole 203a is deformed.

As shown in FIG. 16, when the rotor housing hole 203 is not deformed, the rotor stationary angle θ is approximately 40°. Note that the rotor static angle θ is the rotor angle at which the torque is approximately zero.
When the rotor housing hole 203a is deformed, the rotor stationary angle θ is approximately 10°.
When the rotor housing hole 203 is not deformed, the cogging torque (potential energy) is approximately 0.5 [μNm]. Note that the cogging torque is the maximum value of torque.
When the rotor housing hole 203a is deformed, the cogging torque is approximately 1.1 [μNm].

Next, examples of cogging torque, stored energy, and integral torque with respect to the rotor angle will be described.
FIG. 17A is a diagram showing changes in cogging torque with respect to the rotor angle when the rotor housing hole 203 is not deformed. FIG. 17B is a diagram showing changes in stored energy with respect to the rotor angle when the rotor housing hole 203 is not deformed. FIG. 17C is a diagram showing changes in integral torque with respect to the rotor angle when the rotor housing hole 203 is not deformed.

In FIG. 17A, the horizontal axis is the rotor angle [deg] and the vertical axis is the cogging torque [μNm]. In FIG. 17B, the horizontal axis is the rotor angle [deg] and the vertical axis is the accumulated energy [μJ]. In FIG. 17C, the horizontal axis is the rotor angle [deg] and the vertical axis is the integrated torque [μNm].

17, when the rotor housing hole 203 is not deformed, the holding torque is about 0.514 [μNm], the stored energy ΔΕ is about 0.421 [μJ], and the static angle is about 131.7. [deg] and the balance is 0.024. Note that the holding torque is the average value of the maximum and minimum torque values. The stored energy ΔΕ is the difference between the maximum and minimum stored energy. The static angle is an interpolated value at the low potential position. Balance is the maximum and minimum torque divided by the holding torque.
The low potential position has an elementary angle of about 130 [deg], an operation of about 31 [deg], and an interpolation of 131.68. Note that the elementary angle is the angle at which the integrated torque becomes the minimum value.
The work is the value based on the minimum value of the integral torque.
The high potential position has an elementary angle of about 40 [deg], an operation of about 13 [deg], and an interpolated value of 42.53.

FIG. 18A is a diagram showing changes in cogging torque with respect to the rotor angle when the rotor housing hole 203a is deformed. FIG. 18B is a diagram showing changes in stored energy with respect to the rotor angle when the rotor housing hole 203a is deformed. FIG. 18C is a diagram showing changes in integral torque with respect to the rotor angle when the rotor housing hole 203a is deformed.

In FIG. 18A, the horizontal axis is the rotor angle [deg] and the vertical axis is the cogging torque [μNm]. In FIG. 18B, the horizontal axis is the rotor angle [deg] and the vertical axis is the accumulated energy [μJ]. In FIG. 18C, the horizontal axis is the rotor angle [deg] and the vertical axis is the integrated torque [μNm].

From FIG. 18, when the rotor housing hole 203a is deformed, the holding torque is about 1.147 [μNm], the stored energy ΔΕ is about 0.962 [μJ], and the static angle is about 104.4. [deg] and the balance is 0.043.
The low potential position has an elementary angle of about 100 [deg], an operation of about 25 [deg], and an interpolated value of 104.43.
The high potential position has an elementary angle of about 180 [deg], an operation of about 41 [deg], and an interpolation of 0.

As described with reference to FIG. 16, when the rotor housing hole 203a is deformed, the rotor stationary angle deviates and the cogging torque increases compared to when the rotor housing hole 203a is not deformed.
As described with reference to FIGS. 17 and 18, when the rotor housing hole 203a is deformed, each of the holding torque, the stored energy ΔΕ, and the static angle deviates compared to when the rotor housing hole 203a is not deformed. . Furthermore, when the rotor housing hole 203a is deformed, the elementary angle at the low potential position and the elementary angle at the high potential position are shifted compared to when the rotor housing hole 203a is not deformed.
When the rotor housing hole 203a is deformed in this manner, the characteristics of the stepping motor deviate, and the stepping motor may not have the desired performance.

On the other hand, according to the present embodiment, since the stator 201 is manufactured by punching after forming the fusion zone, the rotor housing hole 203 can be manufactured in a perfectly circular state without being deformed. As a result, by using the stator 201 manufactured according to this embodiment, a stepping motor with desired performance can be manufactured.
Note that the rotor housing hole 203 in the stator 201 manufactured by the manufacturing method of the present embodiment has a lower limit of 0 [μm] with respect to the design value of the diameter of the arc of the portion excluding the notches 204 and 205 of 1.8 mm. , the upper limit is 9 [μm]. Therefore, the circularity of the rotor housing hole 203 in the stator 201 manufactured by the manufacturing method of this embodiment is approximately 99.5% (=1-(9×10 ⁻⁶ /0.0018)).

<Modified example of embodiment>
Modifications of the above-described embodiment will be described below.
In the second manufacturing process, as described with reference to FIGS. 5 and 6, an example in which chromium is applied linearly in the longitudinal direction (x-axis direction) of the hoop material has been described, but the present invention is not limited to this.
FIG. 19 is a diagram showing a modification of chromium coating according to this embodiment. The difference from FIG. 6 is that chromium is applied to the regions corresponding to the narrow portions 210 and 211 of the stator 201 . In this modification, in the second manufacturing process, the paste applying device 322 applies chromium paste to the regions 332 corresponding to the narrow portions 210 and 211 of the hoop material 310B with reference to the guide holes 312 and 313. You may do so.
Thereby, according to the variant, the amount of chromium to be applied can be reduced. Furthermore, according to the modification, the heat generated in the hoop material can be reduced by reducing the positions irradiated with the laser.

In the above example, chromium is linearly applied in the longitudinal direction (x-axis direction) of the hoop material, but a mask may be applied to form a chromium layer by chromium plating.
FIG. 20 is a diagram showing a chromium layer formed on the hoop material according to this embodiment. FIG. 20A is a perspective view of a hoop member 310C after forming a chrome layer in a modified example. FIG. 20(B) is a cross-sectional view of the hoop material 310C taken along line YY' of FIG. 20(A) after forming the chrome layer. In addition, in FIG. 20, the guide holes are omitted. Symbol g331c is a chrome layer formed by chrome plating.
Also in this modification, the chromium layer 331c may be formed, for example, linearly in the regions corresponding to the narrow portions 210 and 211 with reference to the guide holes in the second manufacturing process.
Alternatively, with the guide holes 312 and 313 as a reference, chrome plate members 331C may be embedded in regions corresponding to the narrow portions 210 and 211 of the hoop member 310C.

Also, in the above example, the stepping motor is a one-coil motor, and the example in which the stator is manufactured in accordance with this has been described, but the present invention is not limited to this. The stepping motor may be a two coil motor.
FIG. 21 is a front view of a modified two-coil motor stator 201A'' before being punched out from a hoop material 310D.

Numerals 210a, 210b and 210c are narrow portions. Positions 311Da, 331Db, and 331Dc are positions where chromium is applied and laser is irradiated.
Also in this case, in the second manufacturing process, the manufacturing system 300 (see FIG. 5) uses the guide holes 312 and 313 as a reference to form the regions 311Da, 331Db, and 331Dc corresponding to the narrow portions 210a, 210b, and 210c. Apply chrome.
Subsequently, in the second manufacturing process, the manufacturing system 300 uses the guide holes 312, 313 as a reference to irradiate the regions 311Da, 331Db, and 331Dc corresponding to the narrow portions 210a, 210b, and 210c with a laser to form the melted portions. form.
Subsequently, the manufacturing system 300 randomly punches the stator 201A with reference to the guide hole in the third manufacturing process, and performs magnetic annealing treatment in the fourth manufacturing process, thereby manufacturing the stator 201A for the two-coil motor. can.
In this modification as well, the stator 201A is manufactured by stamping the hoop material after forming the melted portions in the narrow portions 210a, 210b, and 210c. can be created with great precision.

In the examples shown in FIGS. 6, 19 and 21, the stators are manufactured by punching the hoop material in one direction, but the stators are punched alternately as shown in FIG. may FIG. 22 is a front view of a stator for a two-coil motor in a modified example before being pressed.
In this modified example, in the second manufacturing process, manufacturing system 300 applies chromium to a region corresponding to stator 201B with reference to guide holes 312 and 313, and irradiates a laser.
Although FIG. 22 shows an example of a stator for a two-coil motor, a stator for a one-coil motor can also be manufactured in the same manner by arranging them alternately. In this case, for example, in FIG. 19, the areas 332 corresponding to the narrow portions 210 and 211 may be coated not only on the guide hole 313 side but also on the guide hole 312 side.
Also, the stator has been described as an example in which it is arranged at approximately 90 degrees with respect to the hoop material, but the present invention is not limited to this. The stator angle to the hoop may not be 90 degrees. In that case, chromium may be applied to the area forming the non-magnetic area.

Note that when a material other than 38 permalloy in which the mass % of Ni is 38% is used as the magnetic material, the weight ratio of chromium in the material is different from 15% as described above. For example, when a material such as Ni-2Cr whose chromium weight ratio that indicates a non-magnetic region on the ternary alloy diagram (Fig. 11) is not 15% is used as a magnetic material, the chromium weight ratio must be at least 15% in that material. becomes.

<Description of another third manufacturing process>
In the example of FIG. 5, the press device 342 (FIG. 5), which is the finishing device, performs the punching in the third manufacturing process. However, the third manufacturing process is not limited to this.

FIG. 23 is a diagram showing an example in which the third manufacturing step in the stator manufacturing method according to this embodiment is performed by laser cutting.
In this example, instead of the press device 342 of FIG. 5, for example, a laser cutting device (finishing device) configured as shown in FIG. 23 is used for processing.

As shown in FIG. 23, the laser cutting device includes a laser transmitter (a solid state laser transmitter such as a YAG laser or disk laser or a fiber laser transmitter) 501, an optical fiber 502 connected to the laser transmitter 501, and an optical fiber 502 and a laser head 504 connected via a laser emitting portion 503 connected to the other end of the laser head 504 . The laser head 504 has a collimation lens 506 for collimating the laser beam 505 emitted from the laser emitting portion 503 and a condenser lens 507 for condensing the collimated laser beam 505 . The cutting nozzle 511 is connected through an assist gas pipe 508 to an assist gas supply device 509 (assist gas is N ₂ with a volume % of 90% or more or an inert gas such as argon or helium) 509 . A laser beam 505 condensed by a condensing lens 507 and an assist gas 510 are emitted below the cutting nozzle 511 . A material to be cut (magnetic plate material) 512 is placed with a space of, for example, 2 to 3 mm from the lower surface of the cutting nozzle 511, and laser cutting is performed.
This material to be cut (magnetic plate material) 512 is a part of the state in which the hoop material after the second manufacturing process in FIG. 5 is wound.
Note that the configuration example of the laser cutting apparatus shown in FIG. 23 is just an example, and the present invention is not limited to this.

FIG. 24 is a diagram showing an example in which the third manufacturing step in the stator manufacturing method according to the present embodiment is performed by wire electrical discharge machining.
In this example, instead of the press device 342 in FIG. 5, for example, a wire electric discharge machine (finishing machine) configured as shown in FIG. 24 is used.

As shown in FIG. 24, in wire electric discharge machining, a wire electrode 601 travels along upper and lower guide rollers 602 and wire guides 603 and is taken up as indicated by arrows. The wire electrode 601 is given a required tension and movement speed by a brake and a take-up device (not shown), and the material to be cut (magnetic plate material) 609 is opposed to the wire electrode 601 which moves linearly between the wire guides 603 for processing. do. Reference numeral 608 denotes an XY table on which a material to be cut (magnetic plate material) 609 is placed and which is movable in the X-axis and Y-axis directions. Reference numeral 604 denotes machining fluid nozzles for supplying machining fluid, which are provided above and below a material to be cut (magnetic plate material) 608 and are provided coaxially with the wire electrode 601 so as to wrap the wire guide 603 . A machining power source 606 is connected to the wire electrode 601 by an electric current (not shown), performs pulse discharge between the wire electrode 601 and a material to be cut (magnetic plate material) 609, and cuts the material to be cut (magnetic plate material) 609 by electrical discharge machining. cutting is performed. Reference numeral 607 is an NC device that performs various controls in this wire electric discharge machining.
This material to be cut (magnetic plate material) 609 is a part of the wound hoop material after the second manufacturing process in FIG.
Note that the configuration example of the wire electric discharge machining apparatus shown in FIG. 24 is merely an example, and the present invention is not limited to this.

Note that the third manufacturing process is not limited to punching (FIG. 5), laser cutting (FIG. 23), and wire electric discharge machining (FIG. 24), and may be other cutting methods, processing methods, or non-contact cutting methods. .

As described above, the mode for carrying out the present invention has been described using the embodiments, but the present invention is not limited to such embodiments at all, and various modifications and replacements can be made without departing from the scope of the present invention. can be added.

REFERENCE SIGNS LIST 1 clock 2 battery 3 oscillator circuit 4 frequency divider circuit 5 control circuit 6 pulse drive circuit 7 stepping motor 8 analog clock section 12 hour hand 13 minute hand 14 Second hand 15 Calendar display portion 81 Watch case 82 Watch movement 201 Stator 202 Rotor 208 Magnetic core 209 Coil 210, 211 Narrow portion 401 Melting portion 220 Screw 203 Rotor accommodation hole 218a Screw hole 218b Screw hole 220 Screw 300 Manufacturing system 302 Pressing device 322 Paste coating device 323 Drying device 324 Laser irradiation device 325... Cleaning device, 342... Press device (finishing device), 312, 313... Guide hole, 310... Hoop material, 331... Non-magnetic area

Claims (8)

a non-magnetization step of forming a non-magnetic region in the magnetic plate;
a step of machining the magnetic plate material to form a rotor hole for a motor, the machining step of machining a portion of the non-magnetic region;
including
The demagnetization step includes:
a chromium applying step of applying chromium to the magnetic plate;
a laser irradiation step of irradiating the magnetic plate material with a laser from the thickness direction;
A method of manufacturing a stator for a motor, comprising: a non-magnetization step of forming a non-magnetic region in the magnetic plate;
a step of machining the magnetic plate material to form a rotor hole for a motor, the machining step of machining a portion of the non-magnetic region;
including
The demagnetization step includes:
a chromium coating step of continuously coating the magnetic plate with chromium;
a laser irradiation step of irradiating the magnetic plate material with a laser from the thickness direction;
A method of manufacturing a stator for a motor, comprising : including a guide hole forming step of forming a guide hole in the magnetic plate before the demagnetizing step;
In the chromium application step, the chromium is applied with reference to the guide hole,
The laser irradiation step includes irradiating a laser with reference to the guide hole,
The processing step includes processing a portion of the non-magnetic region with reference to the guide hole.
3. A method for manufacturing a motor stator according to claim 1 or 2 . The processing step includes
one of processing a portion of the non-magnetic region by punching, processing a portion of the non-magnetic region by laser cutting, and processing a portion of the non-magnetic region by wire electric discharge. 4. A method of manufacturing a motor stator according to claim 1 . A non-magnetic melting region formed around a rotor hole in a magnetic plate material and in which the magnetic plate material is demagnetized by melting, and is cut from one surface side of the magnetic plate material toward the other surface side in the thickness direction. a non-magnetic melting region with a smaller area;
A stator for a motor. The circularity of the rotor hole is 99.5% or more,
The stator for a motor according to claim 5 . The magnetic plate material is
An alloy containing Fe, Ni, and Cr containing 37.5% to 38.5% nickel, 7.5% to 8.5% chromium, and 52.5% to 54.5% iron. is a plate material ,
The non-magnetic melting region is
including a region with a Cr content of 15% or more,
The motor stator according to claim 5 or 6 . The chromium weight of the non-magnetic melting region is 6% to 18% larger than the chromium weight of the magnetic plate excluding the non-magnetic melting region,
The motor stator according to claim 5 or 6 .

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