JPH0556004B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electromagnetic laminated core used in electrical equipment such as transformers and actuators. [Prior Art] There are two types of electrical steel sheets used in electrical equipment: non-oriented electrical steel sheets and grain-oriented electrical steel sheets. The magnetic properties of these electrical steel sheets depend on the alignment of iron crystals. Iron crystals have a structure called a body-centered cubic lattice, in which iron atoms are arranged at each vertex of a cube and at its center. The ease with which magnetic lines of force penetrate through iron varies depending on the direction of magnetization and the direction of atomic arrangement in the crystal (crystal orientation). The ridge direction [100] is the easiest to see through, followed by the plane diagonal direction [110] and the body diagonal direction [111] the worst. Directional (unidirectional) electromagnetic steel sheet in which the ridge direction [100], where magnetic lines of force are most transparent, is neatly aligned in the rolling direction.
It is called electromagnetic steel sheet. Further, an electrical steel sheet in which the direction is random is called a non-oriented electrical steel sheet. Unidirectional electrical steel sheets have good magnetism in the rolling direction (longitudinal direction), but are very poor in other directions, such as the direction perpendicular to rolling (width direction) or the thickness direction.
On the other hand, non-oriented electrical steel sheets show slightly better magnetism in the rolling direction, but are almost uniform in all directions. Generally, in a transformer, the direction of the lines of magnetic force always flows in a constant manner, so the direction is matched with the rolling direction of the grain-oriented electrical steel sheet. On the other hand, in rotating machines such as motors, the direction of magnetic lines of force is constantly changing, so non-oriented electrical steel sheets are used. When using a unidirectional electrical steel sheet, a wound core transformer can match the direction of the magnetic flux with the magnetization direction of the steel sheet, but the manufacturing method is more complicated than that of a laminated core. Therefore, the iron core is divided into a yoke part (yoke part) and a leg part (leg part), and each
There is a structure in which an iron core is formed by using electromagnetic steel sheets having an axis of easy magnetization along the flow direction of magnetic flux and joining these sheets together. However, in a laminated core transformer with such a complicated shape, not only is the manufacturing process complicated, but also the flow of magnetic flux is complicated at the joints between the yoke and the leg iron, and the magnetic circuit is not always correct. It is not possible to maintain magnetic properties throughout. In contrast to such conventional electromagnetic steel sheets, bidirectional electromagnetic steel sheets have been proposed (for example,
(See Publication No. 21857). This has an axis of easy magnetization in the rolling direction and in a direction perpendicular to the rolling direction. This bidirectional electrical steel sheet has excellent magnetic properties in two directions, so it has superior properties compared to unidirectional electrical steel sheets, and is expected to be applied to applications such as transformer cores. has been done. By the way, in unidirectional electrical steel sheets, <100
> When tension is applied to the axis, the magnetic domains are subdivided,
It is known that iron loss, especially abnormal eddy current loss among eddy current losses, is reduced. This abnormal eddy current loss is an eddy current loss based on the movement of domain walls, and its analysis has been conducted only recently when magnetic domain theory and magnetic domain observation were developed. In grain-oriented electrical steel sheets,
This abnormal eddy current loss accounts for approximately 50% of the total iron loss. FIG. 6 shows this situation. In this figure, when tension is applied in the direction of the easy magnetization axis <100>,
It appears that the abnormal eddy current loss is reduced. This is thought to be because when tension is applied, the magnetic domains are deformed, and the axis of easy magnetization <100> is aligned in the direction of tension. [Problems to be solved by the invention] In unidirectional electrical steel sheets, abnormal eddy current loss can be reduced by applying tension in one direction, but in bidirectional electrical steel sheets,
In order to reduce the abnormal eddy current loss, tension must be applied simultaneously in the directions of the two easy magnetization axes, which is not realistic. Therefore, an object of the present invention is to reduce the iron loss of a bidirectional electrical steel sheet by simultaneously applying a tension effect in two directions even if the force is applied in one direction. [Means for Solving the Problems] In order to achieve the above object, the laminated core of the present invention has the following features:
It is characterized by comprising means for applying a surface pressure of 0.3 Kgf/cm ² or more perpendicular to the laminated surface of the iron core. [Function] In the present invention, a bidirectional electrical steel sheet is used for the laminated core, and a surface pressure is applied perpendicularly to the laminated surface in the state of the laminated core. In a bidirectional electrical steel sheet, easy magnetization axes are formed in the rolling direction and a direction (width direction) perpendicular thereto. If compressive force is applied in the thickness direction,
The same effect as when tension is applied in the directions of the two easy magnetization axes of the plate surface is produced, and iron loss due to abnormal eddy current loss can be reduced. In other words, by applying surface pressure, the magnetic domain in the plate thickness direction is divided into two magnetic domains in two directions parallel to the plate surface.
And these magnetic domains are subdivided. Therefore, the properties in two directions are improved, especially the magnetization properties in a low magnetic field. Figures 4 and 5 show that 3% Si bidirectional electrical steel sheets are cut into ring shapes and laminated to form an iron core.
It shows the magnetic properties measured by applying stress to the laminated surface. FIG. 4 shows the results of measuring the coercive force H _c while changing the surface pressure, and FIG. 5 shows the results of measuring the initial magnetic permeability μ _i . As you can see from these graphs, the surface pressure is 0.3
At Kgf/ ^cm2 , the coercive force _Hc decreases rapidly,
It can be seen that there is an inflection point where the initial magnetic permeability μ _i rapidly increases. Therefore, if a surface pressure of 0.3 Kgf/cm ² or more is applied to the laminated surfaces, the effect of improving magnetic properties can be obtained. [Examples] Hereinafter, the present invention will be specifically described based on Examples. C0.048wt%, Si3.40wt%, Mn0.14wt%,
A hot rolled plate with a thickness of 1.65 mm consisting of 0.023% by weight of acid-soluble Al, 0.0035% by weight of total N, the balance Fe and unavoidable impurities was annealed at 1070℃ for 2 minutes, and the rolling reduction was applied in the same direction as the hot rolling direction. Cold rolled at 65%. Then,
It was cold rolled in a direction crossing this rolling direction at a reduction rate of 60%, and finished to a final plate thickness of 0.23 mm. This cold-rolled sheet was decarburized and annealed at 810°C for 90 seconds in a wet hydrogen atmosphere. After decarburization annealing, a magnesia-based annealing separation agent was applied to the surface of the steel plate, and annealing was performed at 1200℃ x 20 in an atmosphere of 100% _H2 .
Final annealing was performed for an hour and secondary recrystallization was performed. As a result, a bidirectional electrical steel sheet with (100) <001> oriented grains was obtained. Then, this bidirectional electrical steel sheet was annealed at 850°C and 600°C for 1 hour, respectively.
The results are shown in Table 1.

〔Effect of the invention〕

As described above, in the present invention, perpendicular to the laminated surface of the core in which bidirectional electrical steel sheets are laminated,
It is equipped with means for applying a surface pressure of 0.3 Kgf/cm ² or more. In bidirectional electrical steel sheets, the easy magnetization axes are formed in the rolling direction and the direction perpendicular thereto (width direction), so if compressive force is applied in the sheet thickness direction, the two easy magnetization axes on the sheet surface are The same effect as when tension is applied is produced, and iron loss caused by abnormal eddy current loss can be reduced. As a result, a high-performance laminated core with low core loss can be obtained as a core for electrical equipment such as transformers and actuators.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention;
Fig. 2 is a side view of the laminated state, Fig. 3 is a diagram showing another embodiment of the present invention, Fig. 4 is a graph showing changes in coercive force when surface pressure is changed, and Fig. 5 is a graph showing changes in coercive force when surface pressure is changed. FIG. 6 is a graph showing changes in initial magnetic permeability when surface pressure is changed, and FIG. 6 is a diagram showing how abnormal eddy current loss in a grain-oriented electrical steel sheet changes depending on tension. 1: Laminated core 2, 3: End plate 4: Bead
5: Copper winding.

Claims (1)

[Claims] 1 In an iron core laminated with bidirectional electrical steel sheets,
A laminated iron core comprising means for applying a surface pressure of 0.3 Kgf/cm ² or more perpendicular to the laminated surface of the iron core.