JP2952169B2 - Motor core material with insulating coating on the surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core material and a material for a core material, and more particularly to a core material and a material for a core material used in electromagnetic equipment such as a motor and a transformer.

[0002]

2. Description of the Related Art Conventionally, for example, a cold-rolled steel strip specified in JIS G3141 is punched, and the punched steel sheets are laminated to form a core material for a motor core. Usually, oxygen in the air adheres to the surface of the cold-rolled steel strip to form an oxide film. Due to this oxide film, the surface of the steel sheet has surface resistance. However, this surface resistance is a very small value and is unstable. Therefore, when the steel plates are stacked and come into contact with each other, they are electrically connected.

When the steel plates are electrically connected, a large amount of eddy current flows and eddy current loss increases. Further, when the motor is rotated at a rated voltage with no load due to an increase in eddy current loss, there is a problem that a current value flowing through the motor (hereinafter, referred to as a motor current value) increases. In addition, there is a problem that when the motor current value increases, the power consumption increases, and the consumption of a battery or the like becomes faster.

[0004] As a countermeasure, it has been considered that an insulating sheet or the like is interposed between the steel plates to completely insulate the steel plates and reduce the eddy current to reduce the motor current value. In addition to this, as shown in JP-A-5-109545,
A proposal has been made to increase the contact resistance between steel sheets by interposing an amorphous soft magnetic material between the steel sheets.

[0005]

However, in the former case, since the insulating sheet is interposed between the steel plates, there is a problem that the size of the core material itself becomes large.

In the latter case, since the amorphous soft magnetic material is interposed between the steel plates, the size of the core material itself can be reduced more than the insulating sheet. However, since the cost of the amorphous soft magnetic material and the number of devices and steps for interposing the amorphous soft magnetic material between the steel sheets are increased, there is a problem that the production becomes complicated and the cost is significantly increased.

[0007] Similarly, in the former case, there is a problem that the material cost of the insulating sheet increases and the number of steps for interposing the insulating sheet between the steel sheets increases. The present invention has been made to solve the above problems, and a first object of the present invention is to reduce the size of a core material and reduce the eddy current to reduce the motor current value. It is to provide a core material and a material for a core material.

A second object of the present invention is to provide a core material and a material for a core material which can prevent cost increase without providing a special device and process. A third object is to provide a core material that can be easily manufactured.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of punching a cold-rolled steel strip by pressing.
It is constituted by laminating a predetermined number of formed steel sheets ,
The gist of the present invention is a motor core material in which an oxide film having a thickness of 8 nm to 20 nm is formed on the surface of the rope plate to increase the contact resistance between the steel plates in contact with each other , and the surface is coated with an insulating coating. .

[0010]

[0011]

[0012]

According to the first aspect of the present invention, an oxide film is formed on the surface of the steel sheet, and the oxide film increases the contact resistance between the steel sheets. The eddy current flowing through the core material is reduced by the contact resistance, and the motor current value can be reduced. Further, since the oxide film formed on the surface of the steel sheet is thin, the size of the core material can be reduced. Furthermore, the oxide film formed on the surface of the steel sheet can be easily formed by heat treatment or the like, and without using any special material.
It is possible to increase the contact resistance between the steel plates.

The oxide film formed on the surface of the steel sheet is 8
Since it is formed to a thickness of at least nm, the surface resistance of the steel sheet can be at least 9 mΩ. Therefore, it is possible to increase the contact resistance between the steel plates and reduce the eddy current flowing through the core material. Oxide film with a thickness of 20 nm or more
Large energy is required to form. I
If the thickness of the oxide film exceeds 20 nm, the core material
Adhesion with the insulating coating applied to the surface of the metal is reduced.

[0014]

[0015]

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIG.
Is a thickness t = 0.8 m formed in a predetermined shape
and about 30 to 60 steel sheets 2 each having a m. The rotation shaft 3 is inserted through the center of the core material 1. As shown in FIG. 2, an oxide film 5 is formed on the surface 2a of the steel plate 2. Therefore, the oxide film 5 is interposed between the steel sheets 2 overlapping each other. Therefore, the value of the surface resistance of the steel plate 2 is large. The oxide film 5 increases the value of the contact resistance between the steel plates 2. The thickness of the oxide film 5 is 8 nm or more.

Next, the relationship between the surface resistance of the steel sheet 2 due to the formation of the oxide film 5 and the motor current value will be described. First, the oxide film 5 is formed on the surface 2a of the steel material 2, and the surface is processed by an appropriate pressing force to remove the influence of burrs and the like. Then, the steel material 2 is sandwiched by a flat electrode with a force of 20 kgf.
At this time, a voltage (12 V in this example) was applied, and the flowing current was measured to measure the surface resistance of the steel material 2.

A plurality of steel materials 2 having the same surface resistance are laminated under pressure to produce a core material 1, and a motor is produced using the core material 1. A rated voltage (12 V in this embodiment) was applied to the motor to rotate it without load, and the motor current flowing at this time was measured. As shown in FIG. 3, it can be seen that the motor current value decreases in inverse proportion as the surface resistance of the steel material 2 constituting the core material 1 increases. Further, the surface resistance of the steel material 2 constituting the core material 1 is 9 m.
By setting the value to Ω or more, the motor current value can be reduced to achieve a substantially constant saturated state.

FIG. 4 shows the relationship between the thickness of the oxide film 5 formed on the surface 2a of the steel material 2 and the surface resistance. It can be seen that when the thickness of the oxide film 5 formed on the surface 2a of the steel material 2 is increased, the surface resistance of the steel material 2 increases almost proportionally.
It is already known that the motor current value can be reduced by setting the surface resistance of the steel material 2 to 9 mΩ or more. Therefore, if the thickness of the oxide film 5 formed on the surface 2a of the steel material 2 is 8 nm or more, the surface resistance can be 9 mΩ or more.

Next, the thickness of the oxide film 5 is evaluated as follows. As shown in FIG. 5, an oxide film 5 is formed on the surface 2a of the steel sheet 2, and the thickness of the oxide film 5 is determined by ESCA.
Analyze by The horizontal axis indicates the sputtering time, and the amount of sputtering per minute is 1.5 nm. The vertical axis indicates the component ratio.

The region from the start of the analysis to the intersection of the carbon C characteristic and the oxygen O 2 characteristic is determined as an organic contaminated layer composed of dust and the like attached to the surface of the oxide film 5. Then, after the oxygen O2 characteristic shows a peak, it gradually falls and becomes a half of the peak, and the region from the intersection of the carbon C characteristic and the oxygen O2 characteristic to the reference is oxidized. It is determined as the thickness of the film 5.
The time in this area is about 3 minutes and 10 seconds, 1.5 minutes per minute.
The thickness of the oxide film 5 is about 4.75 in order to perform the sputtering.
It is determined as nm. In addition, the area of 3 minutes and 40 seconds or more is a layer of the steel sheet 2.

Based on this evaluation, an oxide film 5 having a thickness of 8 nm or more is formed on the surface 2a of the steel plate 2, and the surface resistance is set to 9 mΩ or more. The core material 1 of the motor is manufactured using the steel plate 2 to manufacture the motor. Then
Since the contact resistance between the steel plates 2 increases, the eddy current decreases, and the eddy current loss can be reduced. As a result, the value of the motor current flowing through the motor can be reduced, so that the power consumption can be reduced.

Further, since the thickness of the oxide film 5 formed on the surface 2a of the steel plate 2 is very small, on the order of 10 ^-9 , even if the core material 1 is manufactured by laminating the steel plates 2, The material 1 itself does not increase in size, and can be reduced in size.

Further, since the oxide film 5 can be formed by oxygen in the air, the oxide film 5 can be easily formed on the surface 2a of the steel plate 2 without using any special material.
As a result, since no special material is used, it is possible to prevent an increase in cost.

Next, the manufacturing process of the oxide film 5 formed on the surface 2a of the steel plate 2 will be described. As shown in FIG. 6, the rolled steel strip 7 that has been subjected to the cold rolling is guided by a plurality of tension rollers 8 and guided into an annealing furnace 10. Then, the steel strip 7 is heated to 900 ° C. and subjected to a continuous annealing treatment. The annealed steel strip 7 is guided to a cooling shower process 12 by a guide roller 11. In the cooling shower step 12, the steel strip 7 heated by the annealing treatment is cooled by the cooling water discharged from the shower nozzle 13. At this time, since the surface 7a of the steel strip 7 comes into contact with oxygen in the air, the oxide film 5 is formed on the surface 7a.

Thereafter, the cooled steel strip 7 is guided to a rinsing step 16 by a guide roller 15. In the rinsing step 16, dust and the like that have been washed by the rinsing liquid discharged from the rinsing nozzle 17 and adhered to the surface 7 a of the steel strip 7 are washed away. Thereafter, the steel strip 7 is dried while being guided by the tension roller 19. The dried steel strip 7 is pressed by the temper rolling roller 20, adjusted to an appropriate hardness, and wound up.

An oxide film 5 having a thickness of 10 nm to 18 nm is formed on the surface 7a of the cold-rolled steel strip 7 manufactured by this process. Oxide film 5 is 10 nm to 18
When the thickness becomes nm, the surface resistance of the steel strip 7 can be maintained at 9 mΩ or more.

Accordingly, the cold-rolled steel strip 7 manufactured as described above is punched out by a press to manufacture the steel sheet 2.
Then, the core material 1 is manufactured by laminating a predetermined number of sheets and laminating under pressure. For this reason, if the steel sheet 2 is formed using the steel strip 7 on which the oxide film 5 is formed, and the steel sheets 2 are stacked and pressed and laminated as in the related art to produce the core material 1, Oxide film 5 is interposed. And the contact resistance between the steel plates 2 can be increased.

As a result, the oxide film 5 is formed on the surface 2a of the steel plate 2.
It is not necessary to provide a special device or process for forming the core material, and the core material 1 can be easily manufactured. In addition, since no special device or process is required, it is possible to prevent an increase in cost.

Further, when the cold-rolled steel strip 7 is manufactured, usually, the steel strip 7 cooled and annealed in the cooling shower process 12 is pickled. The oxide film 5 was forcibly left on the surface 7a.

As a result, even in the process of manufacturing the cold-rolled steel strip 7, since the oxide film 5 is formed on the surface 7 a of the steel strip 7 only by eliminating the pickling, special equipment, processes and materials are required. Since it is not used, it is possible to prevent an increase in cost and to save labor in manufacturing.

In addition, as shown in FIG.
The steel strip 7 annealed by inert gas is made inert (for example, N2
The steel strip 7 that has been heated by the annealing process is guided by the cooling furnace 25 filled with the gas (gas). External air may be blown into the cooling furnace 25 to form the oxide film 5 on the surface 7a of the steel strip 7.

In this case, the surface 7 of the steel strip 7 depends on the amount of external air or oxygen from the oxygen cylinder blown into the cooling furnace 25.
The thickness of the oxide film 5 formed on a can be accurately controlled.

The thickness of the oxide film 5 is preferably not less than 8 nm at which the motor current value becomes low and saturation starts. The thickness of the oxide film 5 is preferably as large as 20 nm or more.
Large energy is required to form the layer 7a. Moreover, when the thickness of the oxide film 5 is 20 nm or more, the adhesion to the insulating coating applied to the surface of the core material 1 is reduced. As a result, it is preferable that the thickness of the oxide film 5 formed on the surfaces 2a and 7a of the steel plate 2 and the steel strip 7 be 8 nm or more and 20 nm or less.

Further, the steel sheet 2 and the steel strip 7 constituting the core material 1
Is 0.8 mm, but this thickness can be arbitrarily changed. Even if the thickness of the steel plate 2 or the steel strip 7 is changed, the thickness of the oxide film 5 formed on the surfaces 2a and 7a may be 8 nm or more and 20 nm or less.

That is, as shown in FIG. 8, when the thickness of the steel plate 2 changes, the characteristics of the motor current value also change. However, the surface resistance of the steel plate 2 at which the motor current value is saturated is 9 mΩ, which is constant regardless of the thickness of the steel plate 2. As a result, in order to make the surface resistance of the steel sheet 2 9 mΩ or more, the thickness of the oxide film 5 may be made 8 nm or more regardless of the thickness of the steel sheet 2.

In this embodiment, the present invention is embodied in the motor core material 1. However, the present invention can be applied to a transformer and other electromagnetic devices. The motor may be a DC motor or an AC motor.

Next, technical ideas other than the claims as understood from the above embodiments are described below together with their effects. (1) An oxide film was formed on the surface of a steel plate or a steel strip so that the surface resistance became 9 mΩ or more.

When the core material is formed of a steel sheet or a steel strip having an oxide film having a surface resistance of 9 mΩ or more, the eddy current can be reduced and the motor current value can be reduced.
As a result, the core material can be reduced in size, and a motor with low power consumption can be manufactured.

[0040]

As described above in detail, according to the present invention, the contact resistance between steel sheets can be increased without using any special material, and the oxide film is extremely thin, so that the core material can be reduced in size. Can be achieved. The oxide film can be easily formed by a heat treatment or the like without using a special material. As a result, the power consumption can be reduced by reducing the eddy current to reduce the motor current value. In addition, since the oxide film can be easily formed without using a special material, an increase in cost can be prevented.

The oxide film formed on the surface of the steel sheet is 8
Since it is formed to a thickness of at least nm, the surface resistance of the steel sheet can be at least 9 mΩ. As a result, the contact resistance between the steel plates can be maintained at a certain contact resistance or more, and the eddy current flowing through the core material can be reduced.
Also, in order to form an oxide film having a thickness of 20 nm or more.
Requires a lot of energy, and the thickness of the oxide film
Insulation coating applied to the surface of the core material when it exceeds 20nm
The thickness of the oxide film is from 8 nm to
Preferably it is 20 nm.

[0042]

[0043]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a core material according to the present invention.

FIG. 2 is a partially enlarged view showing that an oxide film is formed on the surface of the steel sheet.

FIG. 3 is a characteristic diagram showing characteristics of a motor current value with respect to a surface resistance of a steel plate.

FIG. 4 is a characteristic diagram showing characteristics of a surface resistance of a steel sheet with respect to a thickness of an oxide film.

FIG. 5 is an explanatory diagram for explaining evaluation of the thickness of an oxide film.

FIG. 6 is an explanatory view showing a step of forming an oxide film on the surface of a steel strip.

FIG. 7 is an explanatory view showing a step of forming an oxide film on the surface of a steel strip.

FIG. 8 is a characteristic diagram showing characteristics of a motor current value with respect to a surface resistance of a steel sheet when a thickness of the steel sheet is changed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Core material, 2 ... Steel plate, 2a ... Surface, 5 ... Oxide film, 7
... steel strip, 7a ... surface

Claims (1)

(57) [Claims] 1. Stamping from a cold-rolled steel strip by a press
It is constituted by laminating a predetermined number of formed steel sheets ,
Mo having a thickness on the surface of the steel plate to form an oxide film as a 8Nm～20nm, characterized in that to increase the contact resistance between the steel sheets in contact with each other, subjected to insulating coating on the surface
Core material for data.