JP7328522B2 - motor core - Google Patents

Description

The present invention relates to motor cores.

An iron core (motor core) of a motor used in an electric vehicle, a hybrid vehicle, or the like is formed by laminating non-oriented electrical steel sheets. One of the causes of the deterioration of the iron loss of the motor core is the strain due to the punching of the steel plate. Reference 5).

In addition, in order to prevent the stacked non-oriented electrical steel sheets from shifting, mainly the back yoke is formed with minute projections (if the bottom surface is a projection, the top surface is a recess), and these are laminated adjacent to the bottom surface. They are fixed to each other by being pushed into the concave portion (the upper portion is the concave portion) of the electromagnetic steel sheet, and this is called "caulking".

Japanese Patent No. 3993689 JP-A-58-104125 Japanese Patent No. 6270305 International Publication 2013/111726 JP 2017-110243 A

However, in the motor core fixed by caulking, the strain is released by the additional annealing, and although the iron loss is reduced due to this, the loss due to the short circuit between layers may also occur. This has been a cause of hindering loss reduction.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a motor core having a plurality of non-oriented electrical steel sheets fixed by caulking, and to suppress loss due to inter-layer short-circuiting while performing additional annealing, thereby reducing iron loss as a whole.

The inventors have found that additional annealing of a motor core fixed by caulking causes inter-layer short-circuiting at the caulked portion (the portion where a plurality of non-oriented electrical steel sheets are joined by caulking). We have found that the crimping occurs at the edge of the crimped portion, not on the laminated surface. Then, in order to suppress the interlayer short circuit, it was found that the problem can be solved by controlling the structure (grain size of crystal grains) and hardness to specific conditions, and by embodying this, the present invention completed. The present invention will be described below.

In one aspect of the present invention, a plurality of non-oriented electrical steel sheets are laminated to form a tubular shape, a tubular back yoke, a plurality of teeth arranged on the inner surface of the back yoke, and a plurality of teeth provided on the back yoke. A motor core comprising a crimped portion that joins non-oriented electrical steel sheets, wherein the teeth have a crystal grain size of greater than 10 μm at the tip, or a hardness at a position spaced 0.5 mm from the tip of the tooth. Hv1, when the hardness in the range of 0.05 mm to 0.07 mm from the tip of the tooth is Hv2, the value obtained by dividing Hv2 by Hv1 is smaller than 1.15, and the crimped portion is the crystal at the end of the crimped portion A motor core having a grain size of less than 20 μm.

Another aspect of the present invention is a tubular back yoke formed by laminating a plurality of non-oriented electrical steel sheets, a plurality of teeth arranged on the inner surface of the back yoke, and a plurality of teeth provided on the back yoke. A motor core comprising a crimped portion that joins non-oriented electrical steel sheets, wherein the teeth have a crystal grain size of greater than 10 μm at the tip, or a hardness at a position spaced 0.5 mm from the tip of the tooth. Hv1, when the hardness in the range of 0.05 mm to 0.07 mm from the tip of the tooth is Hv2, the value obtained by dividing Hv2 by Hv1 is smaller than 1.15, and the crimped portion is 0 from the end of the crimped portion. When the hardness in the range from 0.05 mm to 0.07 mm is Hv3, the value obtained by dividing Hv3 by Hv1 is 1.05 or more.

Another aspect of the present invention is a tubular back yoke formed by laminating a plurality of non-oriented electrical steel sheets, a plurality of teeth arranged on the inner surface of the back yoke, and a plurality of teeth provided on the back yoke. A motor core comprising a crimped portion that joins non-oriented electrical steel sheets, wherein the teeth have a crystal grain size of greater than 10 μm at the tip, or a hardness at a position spaced 0.5 mm from the tip of the tooth. Hv1, when the hardness in the range of 0.05 mm to 0.07 mm from the tip of the tooth is Hv2, the value obtained by dividing Hv2 by Hv1 is smaller than 1.15, and the crimped portion is the crystal at the end of the crimped portion The motor core has a value obtained by dividing D3 by D1, where D3 is the grain diameter and D1 is the grain diameter of the crystal grain at a position 0.5 mm away from the tip of the tooth.

Another aspect of the present invention is a tubular back yoke formed by laminating a plurality of non-oriented electrical steel sheets, a plurality of teeth arranged on the inner surface of the back yoke, and a plurality of teeth provided on the back yoke. A motor core comprising a crimped portion that joins non-oriented electrical steel sheets, wherein the teeth have a grain size D2 of larger than 10 μm at the tip thereof, or the hardness at a position 0.5 mm away from the tip of the tooth is Hv1, and the hardness in the range of 0.05 mm to 0.07 mm from the tip of the tooth is Hv2, the value obtained by dividing Hv2 by Hv1 is less than 1.15, and the grain size at the end of the crimped portion is D3, the value obtained by dividing D2 by D3 is 1.20 or more.

According to the motor core of the present invention, it is possible to suppress interlayer short-circuit loss and reduce iron loss as a whole while performing additional annealing.

2 is an external perspective view of the motor core 10. FIG. 2 is a plan view of a motor core 10; FIG. 3 is an enlarged view of a part of FIG. 2; FIG. 3 is a cross-sectional view of part of the motor core 10. FIG. It is a figure explaining the other aspect of a crimping|crimped part. FIG. 4 is a diagram illustrating an aspect of teeth 12; FIG. 11 is another diagram for explaining the aspect of the tooth 12; 4A and 4B are diagrams for explaining a mode of a crimped portion 14; FIG. FIG. 10 is another diagram for explaining the aspect of the crimped portion 14;

FIG. 1 is an external perspective view of a motor core 10 according to one embodiment. A motor core 10 is formed by laminating a plurality of non-oriented electrical steel sheets 10a. The chemical composition that constitutes the non-oriented electrical steel sheet 10a may be as known, but is preferably as follows, for example.

The content of Si is preferably 0.5% by mass or more and 4% by mass or less. Si can increase the resistivity of steel and improve iron loss characteristics. However, if it exceeds 4% by mass, the steel tends to harden and it becomes difficult to work such as rolling.

Mn is preferably 0.05% by mass or more and 3% by mass or less. Mn, like Si, can increase the specific resistance of steel and improve iron loss characteristics. Also, the hot workability of the steel can be improved. However, if it is less than 0.05% by mass, it is difficult to obtain this effect, and if it exceeds 3% by mass, workability may be adversely affected.

Further, even if an element known to be contained in an electrical steel sheet is arbitrarily contained within a known range in place of Fe, the effects of the present invention are not lost. Examples of these elements include C, Al, N, P, S, Se, Sn, Sb, Ca, Cr, Ni, Cu, B, Ti, Nb, Mo, Mg, La, Ce, and Y. be done. Elements that have a relatively strong effect on the effects of the present invention will be described below.

C is preferably 0.005% by mass or less. When the C content exceeds 0.005% by mass, magnetic aging tends to occur and iron loss increases.

Al is preferably 3% by mass or less. Al, like Si, can improve iron loss characteristics. However, if it exceeds 3% by mass, there is a risk of impairing the rollability.

N is preferably 0.005% by mass or less. N is positioned as an impurity that is inevitably mixed into steel and is an element that degrades the magnetic properties, so it is desirable to reduce it as much as possible.

P is preferably 0.2% by mass or less. When P exceeds 0.2% by mass, the steel tends to harden and rolling becomes difficult.

S is preferably 0.005% by mass or less. S is positioned as an unavoidable impurity and is a harmful element that deteriorates the magnetic properties, so it is preferable to reduce it as much as possible.

Se is preferably 0.0010% by mass or less. Since Se may deteriorate the magnetic properties after strain relief annealing, it is preferable to reduce it as much as possible.

Sn can be contained at 0.003% by mass or more and 0.5% by mass or less. Sn has the effect of improving magnetic flux density and suppressing deterioration of magnetic properties.

Sb can be contained at 0.003% by mass or more and 0.5% by mass or less. Sb also has the effect of improving magnetic flux density and suppressing deterioration of magnetic properties.

Ca can be contained at 0.0010% by mass or more and 0.005% by mass or less. Ca promotes grain growth during stress relief annealing and has the effect of improving iron loss characteristics.

The balance other than the components explained above is Fe and unavoidable impurities.

As described above, the motor core is formed by laminating a plurality of non-oriented electrical steel sheets, and its shape can be considered similar to that of known motor cores. As an example, FIG. 1 shows a perspective view of the motor core 10, and FIGS. 2 and 3 further show other views for explaining the motor core 10. FIG. FIG. 2 is a plan view of the motor core 10 viewed from the direction of arrow II in FIG. FIG. 3 is a part of FIG. 2, and is a diagram extracting and expressing the portion surrounded by III in FIG.

As can be seen from these figures, the motor core 10 is formed by overlapping a plurality of annular non-oriented electrical steel sheets 10a, and has a circular tubular shape as a whole. Therefore, the motor core 10 can be considered as the central axis O of the circular tube (see FIG. 2).

The motor core 10 extends parallel to the central axis O on the inner wall surface of a circular tube, and has slots 11 which are grooves provided at predetermined intervals in the inner circumferential direction. and a back yoke 13 that connects the outer peripheral sides of the teeth 12 and has a tubular shape. Therefore, the teeth are a plurality of partition walls arranged at intervals of the width of the slot 11 on the inner surface of the back yoke.
The specific forms of these slots 11, teeth 12, and back yoke 13 are not limited to this example, and known forms can be applied.

Furthermore, the motor core 10 has a crimped portion 14 on the back yoke 13 . The caulked portion 14 is a portion that joins the plurality of non-oriented electrical steel sheets 10a to each other. In the caulked portion 14, unevenness is provided in the thickness direction of the non-oriented electrical steel sheet 10a, and these are fitted and engaged (caulked) to join. The form of caulking is well known, and the plane shapes shown in FIGS. 1 to 3 include, for example, a square shape and a round shape.
When the entire caulked portion is engaged while forming uniform unevenness in the direction of the central axis O, the cross-sectional view along the line IV-IV in FIG. 3 is shown in FIG. As shown in FIG. 4(b), which is a cross-sectional view taken along the line indicated by VV, both have the same aspect. In this case, the amount of protrusion of the step in the direction of the central axis O of the crimped portion 14 is designed to be smaller than the plate thickness of the non-oriented electrical steel sheet 10a, and the non-oriented electrical steel sheet adjacent in the plate thickness direction is engaged. state.
On the other hand, there is also a mode in which the depth of the unevenness changes in a V shape in the cross section. In this case, for example, a mode as shown in FIG. 5B, which is a cross-sectional view along line VV in FIG. 5(a), which is a cross-sectional view taken along the line IV-IV in FIG. 3, at the deepest position of the V shape. In this case, there is a region where the amount of protrusion of the step in the direction of the central axis O in the crimped portion 14 is larger than the thickness of the non-oriented electrical steel sheet 10a, and the non-oriented electrical steel sheet 10a adjacent in the thickness direction is projected. Since it is in a state of being engaged with a plurality of non-oriented electrical steel sheets, it is possible to achieve a stronger engagement.

The motor core 10 of this embodiment further has the following features. Therefore, the following (1) to (6) are defined first.

(1) Teeth particle size D1
The tooth grain size D1 is the grain size of crystal grains at a position separated by 0.5 mm from the tip of the tooth 12 (the end on the side of the central axis O). Specifically, the particle size is determined as follows. FIG. 6 shows a diagram for explanation. FIG. 6 is an enlarged view of the cross section at the tip of the tooth 12, which has been etched so as to make crystal grains visible.
As shown in FIG. 6, the grain size at a position separated by 0.5 mm from the tip of the tooth 12 is defined as a tooth grain size D1. The tooth grain diameter D1 (μm) is calculated by the following formula, where H1 (μm) is the tooth thickness at the position and A1 is the number of crystal grains present at the position.
D1=H1/A1
For D1, measurements are taken at least 10 locations with little deviation (sufficiently distant locations in a plurality of steel plates or one steel plate), and the average value thereof is used.

(2) Teeth end grain size D2
The tooth end grain size D2 is the grain size of crystal grains at the ends of the teeth 12 (ends on the side of the central axis O). Specifically, the particle size is determined as follows. FIG. 7 shows a diagram for explanation. Similarly to FIG. 6, FIG. 7 is an enlarged view of the cross section at the tip of the tooth 12 on the side of the central axis O, which has been etched so as to reveal the crystal grains.
The tooth grain size D2 (μm) is calculated by the following formula, where H2 (μm) is the tooth thickness at the tip of the tooth, and A2 is the number of crystal grains existing along the tip S of the tooth. However, when calculating the thickness H2 of the tooth, as indicated by C in FIG. Here, "sagging" refers to a portion of the entire plate thickness that has been bent and deformed in the plate thickness direction by punching. The appearance of the surface is shown. Generally, in the breakage in the shearing process, the droop portion is adjacent to the shear deformation portion and the breakage portion. The shear deformation part is the part where the steel plate is rubbed in the plate thickness direction while being in strong contact with the die, and is linearly sheared. show.
D2=H2/A2
For D2, measurements are taken at least 10 locations with little deviation (sufficiently distant locations in a plurality of steel plates or one steel plate), and the average value thereof is used.

(3) Teeth hardness Hv1
The tooth hardness Hv1 is the hardness at a position separated by 0.5 mm from the tip of the tooth 12 (the end on the side of the central axis O). The hardness is set to Vickers hardness under a load of 25 g, and the measurement results are obtained at four points where the thickness is evenly divided as indicated by square (rhombus) marks in FIG. Furthermore, at least 10 points with little deviation (sufficiently distant positions in a plurality of steel sheets or one steel sheet) are measured, and the measured values of a total of 40 points are averaged to obtain tooth hardness Hv1.

(4) Teeth edge hardness Hv2
The tooth end hardness Hv2 is hardness measured so that the center position of the indentation falls within a range of 0.05 mm to 0.07 mm from the tip of the tooth 12 (the end on the side of the central axis O). The hardness is set to Vickers hardness under a load of 25 g, and the measurement results are obtained at four points where the thickness is evenly divided as indicated by square (rhombic) marks in FIG. Furthermore, at least 10 points with little deviation (sufficiently distant points in a plurality of steel sheets or one steel sheet) are measured, and the measured values of a total of 40 points are averaged to obtain tooth hardness Hv2. In this case as well, as indicated by C in FIG. 7, the so-called "who" part is excluded.

(5) Crimped portion end grain size D3
The crimped portion end grain size D3 is the grain size of the crystal grains at the end portion of the crimped portion 14 . Specifically, the particle size is determined as follows. As shown in FIG. 8, the grain size of the crystal grains at the position P, which is the end portion of the crimped portion 14, is defined as the crimped portion end grain size D3. The crimped portion end grain diameter D3 (μm) is calculated by the following formula, where H3 (μm) is the thickness of the crimped portion 14 at the relevant position, and A3 is the number of crystal grains present at the relevant position.
D3=H3/A3
For D3, measurements are performed at least 10 locations with little deviation (sufficiently distant locations in a plurality of steel plates or one steel plate), and the average value thereof is used in the present invention.

Here, as shown in FIG. 4, FIG. 8 shows a form in which the protruding amount of the crimped portion 14 does not exceed the thickness of the adjacent non-oriented electrical steel sheet 10a and no discontinuous portion is produced in the material. On the other hand, in the embodiment in which the crimped portion has a V-shaped cross section, as shown in FIG. 9 in the cross section corresponding to FIG. The end of the discontinuous portion of the material that occurs beyond the thickness of the adjacent non-oriented electrical steel sheet 10a is the position P, the number of crystal grains existing along the tip is A3 as in D2 described above, and " D3 is calculated by setting the plate thickness excluding the droop portion as H3.

(6) Crimped end hardness Hv3
The crimped portion end hardness Hv3 is the hardness of the crimped portion 14 measured so that the center position of the indentation falls within a range of 0.05 mm to 0.07 mm from the end portion P of the crimped portion 14 . The hardness is set to Vickers hardness with a load of 25 g, and the measurement results are obtained at four points that divide the thickness of this portion equally. Furthermore, at least 10 points are measured at less uneven points (sufficiently distant positions in a plurality of steel sheets or one steel sheet), and the measured values of a total of 40 points are averaged to obtain the crimped end hardness Hv3. .

With respect to the above items, the motor core 10 has the following features.
(A) Teeth Since the reduction of iron loss is affected by the strain in the teeth, it is preferable that the grain size is reduced to a predetermined size by recrystallization in strain relaxation by additional annealing. Specifically, it is preferable that the tooth edge particle diameter D2 is larger than 10 μm.
Moreover, the reduction in strain due to additional annealing can also be evaluated by the uniformity of hardness in the teeth. From this point of view, it is preferable that the ratio of the tooth end hardness Hv2 divided by the tooth hardness Hv1 is smaller than 1.15.
Therefore, for Teeth,
D2>10 μm, or
Hv2/Hv1<1.15
It is preferable that at least one of

(B) Crimped portion It has been found that when strain is relaxed by additional annealing as described above, an interlayer short circuit occurs particularly near the end of the crimped portion. On the other hand, the interlayer short circuit can be suppressed by any one of the following configurations in the crimped portion.
For one, it is preferable that the grain diameter D3 at the crimped portion end is smaller than 20 μm.
Secondly, it is preferable that the ratio represented by the value obtained by dividing the crimped portion end hardness Hv3 by the tooth hardness Hv1 is 1.05 or more.
Thirdly, it is preferable that the ratio represented by the value obtained by dividing the crimped portion end portion grain size D3 by the teeth grain size D1 is greater than 1.10.
Therefore, for the crimped part,
D<20 μm,
Hv3/Hv1≧1.05, and
D3/D1>1.10
It is preferable that at least one of

In addition to the above (A) and (B), from the viewpoint of additional annealing by local heating of the teeth, as a result, the ratio expressed by the value obtained by dividing the tooth end grain size D2 by the crimped portion end grain size D3 is 1. .20 or more is preferred. Therefore,
D2/D3≧1.20
is preferably This also produces the above effects.

The method for manufacturing the motor core 10 as described above is not particularly limited except for the heat treatment conditions described below, and known methods can be used. Therefore, a motor core can be obtained by manufacturing a non-oriented electrical steel sheet by a known method and processing it. Specifically, after punching the non-oriented electrical steel sheet as a material into the above-described predetermined shape, this is laminated and crimped (formation of the crimped portion) to form a plurality of laminated layers. Non-oriented electrical steel sheets are joined to form a joined body.
Then, additional annealing is applied to relieve strain caused by punching or caulking. By this additional annealing, the configuration of the motor core is as described in (A) and (B) above. A specific method therefor is not particularly limited, but the following conditions can be mentioned, for example. Under the conditions described here, it is possible to more reliably manufacture the motor core 10 that satisfies the above-described characteristics that can solve the problem by performing heat treatment that causes an intentional temperature deviation depending on the part of the motor core. . Specifically, the heat treatment is performed within the following conditions (C), (D), (E) and (F).

Condition (C) is a prerequisite condition for additional annealing, and is a heat treatment in which at least a part of the steel sheet reaches 500° C. or higher. This relieves at least part of the working strain of the steel plate. This is a prerequisite because if such heat treatment is not performed, there is no need to pay attention to the reduction in iron loss due to the release of working strain in the first place, and no interlayer short circuit occurs at the caulked portion. No issues arise.
Generally, such heat treatments are conducted so as to provide uniformity throughout the core and avoid intentional non-uniformity within the core. Therefore, by performing such a heat treatment, strain release and interlayer short-circuiting occur at the same time, which poses the problem of the present invention.

Condition (D) relates to sufficiently annealing the teeth, and is a heat treatment in which the teeth reach a temperature of 500° C. or higher and the residence time in the temperature range of 500° C. or higher is 10 minutes or longer. The temperature reached is preferably 600° C. or higher, more preferably 700° C. or higher. However, when the tooth reaches a higher temperature, it becomes difficult to control the temperature of the caulked portion, which will be described later, below the required temperature due to heat conduction in the steel plate. The temperature reached by the teeth is preferably 800.degree. The residence time in the temperature range of 500° C. or higher is preferably 20 minutes or longer, more preferably 30 minutes or longer. However, if the residence time is long, it becomes difficult to control the temperature reached at the caulked portion, which will be described later, below a required temperature due to heat conduction in the steel plate. The residence time is preferably 60 minutes or less because the properties of the motor core may be impaired due to oxidation or the like.

Condition (E) is related to sufficiently suppressing the thermal effect on the crimped portion, and the retention time in the temperature range of 500° C. or lower or 450° C. or higher is set to 10 minutes or less. It is a heat treatment that
When the temperature is 500° C. or lower, the temperature reached is preferably 400° C. or lower, more preferably 300° C. or lower.
When the temperature is 450° C. or higher, the residence time is preferably 5 minutes or less, more preferably 2 minutes or less.
At first glance, it seems that if the crimped portion is not sufficiently heat-treated, the working strain around the crimped portion is not released and the iron loss increases. However, in actual use, the magnetic flux passing near the caulked portion is weak, so the effect of residual processing strain in this area on the increase in iron loss of the entire motor core is enough to avoid inter-layer short circuits at the caulked portion. This is sufficiently small and negligible compared to the suppression of iron loss increase due to this, so it does not pose a problem in obtaining the effects of the present invention.

Condition (F) is a preferred heat treatment for simultaneously satisfying condition (D) and condition (E). Specifically, the temperature rise rate of the teeth is set to 2° C./s or more. This allows the teeth to reach the required temperature range before sufficient heat transfer occurs from the teeth whose temperature should be raised to the caulked portion whose temperature rise should be suppressed. It is preferably 10° C./s or more, more preferably 100° C./s or more, and the higher the temperature rise rate, the better.

Known means such as localized heating, heating suppression, or cooling may be appropriately used to form the temperature non-uniformity in the motor core as defined by conditions (D) and (E). Specific examples include the following method.
・Only the teeth and their surroundings are locally heated by induction heating or laser irradiation.
・Heat locally by bringing a heater smaller than the size of the motor core close to the teeth.
・When the entire motor core is placed in a heating furnace and heated, heat is shielded by a heat insulating material at and near the crimped portion to suppress the temperature rise of the portion.
・By bringing a cooled metal member into contact with the crimped part, the temperature rise of the part is suppressed.

Detailed conditions for such heating, heating suppression, or cooling for the heat treatments of conditions (C) to (E) and condition (F) described above may vary depending on the size of the motor core, the configuration of the heating or cooling device, and the It can be set appropriately according to ability. Such settings are routinely used in steel materials of various sizes under various temperature conditions, It is not difficult for a person skilled in the art who performs heat treatment under time and apparatus constraints to set the necessary conditions for the necessary motor core.

With the motor core as described above, it is possible to suppress loss due to short-circuiting between layers while performing additional annealing, and to reduce iron loss as a whole.

The characteristics of motor cores manufactured by changing the conditions of additional annealing were investigated, and iron loss was evaluated. Conditions and results are shown in Table 1.

The motor core had an outer diameter (diameter) of 140 mm, an inner diameter (diameter) of 90 mm, 48 slots, and 80 sheets of non-oriented electromagnetic steel sheets laminated. The non-oriented electrical steel sheet used here is a material containing 3.0% by mass of Si and 0.5% by mass of Mn. It is characterized by an iron loss under excitation of 14 W/kg and a magnetic flux density B50 of 1.68 T.
The crimped portion is provided on the back yoke portion, and has 6 equal center angles, a width (radial direction) of 2 mm, a length (circumferential direction) of 4 mm, and a V-shape (examples in FIGS. 5 and 9) with a pressing depth of 0.5 mm. 8 mm.

In the heat treatment, only the teeth are preferentially heated by a coil brought close to the teeth, the temperature is measured at a position 0.06 mm from the tip of the teeth, and the heat treatment conditions are set based on the temperature reached at this position and the heating rate. It was done by

Regarding the prepared motor core, the grain size, hardness ratio, etc. of the teeth and crimped portions were measured. The measuring method is as described above.
Furthermore, iron loss was measured for each motor core. The iron loss was obtained by inserting a 4-pole pair magnet rotor having an outer diameter of 88 mm and a lamination thickness of 24 mm into the motor core, and measuring the torque T generated when the rotor was externally rotated at a rotational speed f=50 rps. Specifically, the torque T0 was measured when the rotor was rotated in the absence of the motor core, and the iron loss generated inside the motor core was obtained from the following equation.
W=2πf(T−T0)
A comparison of the iron loss is as follows. The ratio was expressed as a percentage with 7 as the standard (100%).

As can be seen from Table 1, No. 1 to No. For No. 4, a reduction in iron loss was observed. In addition, it is a rule about the above crimped part,
D<20 μm,
Hv3/Hv1≧1.05,
D3/D1>1.10, and
D2/D3≧1.2
of which two or more are satisfied. 1 to No. In No. 3, a more remarkable decrease in iron loss could be recognized.

10 Motor Core 11 Slot 12 Teeth 13 Back Yoke 14 Crimped Part

Claims (4)

A tubular back yoke, a plurality of teeth arranged on the inner surface of the back yoke, and the plurality of non-oriented electromagnetic steel sheets provided on the back yoke. A motor core comprising a crimped portion that joins the
The teeth have a crystal grain diameter of more than 10 μm at the tips, a hardness of Hv1 at a position spaced 0.5 mm from the tips of the teeth, and a hardness of 0.05 mm to 0.07 mm from the tips of the teeth. When the hardness in the range is Hv2, the value obtained by dividing the Hv2 by the Hv1 is 1.01 or more and less than 1.15,
The motor core, wherein the crimped portion has a crystal grain size smaller than 20 μm at the end portion of the crimped portion. A tubular back yoke, a plurality of teeth arranged on the inner surface of the back yoke, and the plurality of non-oriented electromagnetic steel sheets provided on the back yoke. A motor core comprising a crimped portion that joins the
The teeth have a grain size of more than 10 μm at the tips, or a hardness of Hv1 at a position spaced 0.5 mm from the tips of the teeth, and a range of 0.05 mm to 0.07 mm from the tips of the teeth. When the hardness at is Hv2, the value obtained by dividing the Hv2 by the Hv1 is smaller than 1.15,
In the motor core, the crimped portion has a hardness of 1.05 or more, which is Hv3 divided by Hv1 in a range of 0.05 mm to 0.07 mm from the end of the crimped portion. A tubular back yoke, a plurality of teeth arranged on the inner surface of the back yoke, and the plurality of non-oriented electromagnetic steel sheets provided on the back yoke. A motor core comprising a crimped portion that joins the
The teeth have a grain size of more than 10 μm at the tips, or a hardness of Hv1 at a position spaced 0.5 mm from the tips of the teeth, and a range of 0.05 mm to 0.07 mm from the tips of the teeth. When the hardness at is Hv2, the value obtained by dividing the Hv2 by the Hv1 is smaller than 1.15,
In the crimped portion, when the grain size of the crystal grains at the end of the crimped portion is D3 and the grain size of the crystal grains at a position separated by 0.5 mm from the tip of the tooth is D1, D3 is divided by D1. motor core, the value of which is greater than 1.10. A tubular back yoke, a plurality of teeth arranged on the inner surface of the back yoke, and the plurality of non-oriented electromagnetic steel sheets provided on the back yoke. A motor core comprising a crimped portion that joins the
The teeth have a crystal grain diameter D2 greater than 10 μm at the tips, or a hardness Hv1 at a position spaced 0.5 mm from the tips of the teeth, and a hardness of 0.05 mm to 0.07 mm from the tips of the teeth. When the hardness in the range is Hv2, the value obtained by dividing the Hv2 by the Hv1 is less than 1.15,
A motor core, wherein a value obtained by dividing D2 by D3 is 1.20 or more, where D3 is a grain size of a crystal grain at an end portion of the crimped portion.

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