JP3828830B2 - Wrapped iron core and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an iron core of a wound transformer having excellent magnetic properties and a method for manufacturing the same.
[0002]
[Prior art]
Directional electrical steel sheets with easy magnetization axes in the rolling direction are used as transformer iron core materials. As a method for producing grain-oriented electrical steel sheets, in Japanese Patent Publication No. Sho 58-26405, in a continuous production facility for grain-oriented electrical steel sheets, a linear strain that is substantially perpendicular to the rolling direction and periodic in the rolling direction is introduced. A method for reducing iron loss is disclosed. The principle of this method is that the 180 ° domain wall spacing is subdivided by the deep circulating magnetic domain in the plate thickness direction formed from the surface strain as a result, and in particular, eddy current loss is reduced, which is called magnetic domain control. . As a method for introducing strain, a method using laser irradiation has been put to practical use as the most excellent method in terms of non-contact, high-speed processing, and controllability.
[0003]
By the way, there are two types of transformer iron cores: a stacked iron core and a wound iron core. In the manufacturing process of the stacked iron core, the grain-oriented electrical steel sheets are only laminated, and there is no need for strain relief annealing because the steel sheets are not particularly deformed. On the other hand, in the manufacturing process of a wound iron core, after laminating steel plates, the steel sheet is wound into a roll shape and compressed into a square iron core shape. At that time, deformation occurs in the steel plate, and thus annealing is performed in order to remove unnecessary distortion. As a result, since the linear distortion imparted by laser irradiation or the like is removed at the same time, the magnetic domain control effect, that is, the iron loss reduction effect disappears. Therefore, conventionally, there has been a problem that magnetic domain-controlled grain-oriented electrical steel sheets can only be used for stacked iron cores.
[0004]
Therefore, as a magnetic domain control method applicable to a wound iron core, a method of forming periodic grooves on the surface of a steel sheet is disclosed in, for example, Japanese Patent Publication No. 63-44804, US Pat. PAT. Various use of a tooth profile press / roll, etching, laser processing, etc. is proposed in Japanese Patent No. 4750949, Japanese Patent Laid-Open No. 7-220913, and the like. The principle of magnetic domain control by groove formation utilizes the difference between the magnetic permeability of the air gap and the steel sheet, generates magnetic poles on the steel sheet surface, and obtains the same magnetic domain refinement effect as the circulating magnetic domain. However, since the source of magnetic domain refinement is limited to the steel plate surface, there is a problem that the effect of reducing iron loss is lower than that due to strain. Further, in order to form a groove in a steel plate, a tooth type press or other mechanical method has a problem of tooth wear, and an etching method complicates the process by resist processing / removal. The groove processing by laser has a problem that the required power is greatly increased compared to the introduction of laser distortion. That is, the magnetic domain control method by laser distortion is excellent in both the magnetic characteristics and the manufacturing process, and it has been desired to use this for a wound iron core.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to form a periodic recirculating magnetic domain by applying strain by laser irradiation, and to make it possible to use a magnetically controlled directional electrical steel sheet for a wound iron core, which has excellent magnetic properties. And providing a manufacturing method thereof.
[0006]
[Means for Solving the Problems]
The present inventors have examined the manufacturing process of the wound iron core in detail, and after performing strain relief annealing in the manufacturing process of the wound iron core, disassemble the stacked steel sheets, one by one or several units We focused on the process of reconstructing the iron core. By performing laser irradiation to give linear or point-sequence distortion to each steel plate in this process, there is no significant loss in conventional manufacturing efficiency, and since there is no annealing process after this process, excellent iron loss It was found that a wound iron core can be manufactured while maintaining the characteristics.
[0007]
That is, the present invention is a wound iron core formed by using a grain-oriented electrical steel sheet and subjected to strain relief annealing, and the steel sheet is rolled on all or part of the surface of the steel sheet constituting the iron core. A wound iron core characterized in that linear or point-like strains approximately perpendicular to the direction are imparted at substantially constant intervals in the rolling direction.
Further, the present invention provides a method for manufacturing a wound iron core using a grain-oriented electrical steel sheet, and after forming a desired wound iron core and performing strain relief annealing, all or one of the steel sheets constituting the iron core. A method for producing a wound iron core is characterized in that linear or point-like strains approximately perpendicular to the rolling direction of the steel sheet are applied to the surface of the portion at substantially constant intervals in the rolling direction.
The present invention also relates to a method for manufacturing a wound iron core using grain-oriented electrical steel sheets, wherein a plurality of steel sheets are superposed to form a desired wound iron core, and the iron core is formed after performing strain relief annealing. The wound iron core is characterized in that all or a part of the surface of the steel sheet is subjected to linear or point-sequence distortions substantially perpendicular to the rolling direction of the steel sheet at substantially constant intervals in the rolling direction. Production method.
The present invention also relates to a method for manufacturing a wound iron core using grain-oriented electrical steel sheets, in which a strip-shaped steel sheet is roll-formed to form a desired wound iron core and subjected to strain relief annealing. In a method of manufacturing a wound iron core, characterized in that in the step of unwinding the core, linear or point-like strains approximately perpendicular to the rolling direction are imparted to the steel sheet surface at approximately regular intervals in the rolling direction. is there.
Moreover, this invention is a manufacturing method of the wound iron core characterized by giving distortion by laser irradiation.
Further, the present invention provides a method for producing a wound iron core characterized in that an insulating film peeling trace on a steel sheet surface is not generated by adjusting a focused beam shape, power density, laser wavelength, or irradiation speed during laser irradiation. It is.
[0008]
Note that the linear or point-sequence distortion defined in the present invention is a compression or tension strain that is a source of generation of circulating magnetic domains, and is a comparison that does not involve melting / re-solidification or deformation of the steel plate base material. This is a weak strain. In addition, it is a strain that disappears in annealing for several hours, for example, 800 ° C., which is a strain relief annealing condition performed in the wound iron core manufacturing process. This strain can be measured by, for example, X-ray diffraction, and the circulating magnetic domain of the strain imparting portion can be observed by an electron microscope for observing the magnetic domain, so that the strain defined in the present invention can be determined. It is. Further, since it disappears by performing strain relief annealing, it is also possible to distinguish from strain generated due to a melted / re-solidified portion or deformation that does not easily disappear by annealing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The operation of the present invention will be described below with reference to examples.
FIG. 1 is an explanatory diagram of a method according to the present invention. First, the grain-oriented electrical steel sheet 1 is cut and laminated. At this time, the rolling direction of the grain-oriented electrical steel sheet corresponds to the L direction in the figure. Next, after winding in a roll shape, it is formed into a desired square shape. Thereafter, annealing is performed to remove the distortion of the deformed portion. The annealing temperature and time are, for example, 800 ° C. and 4 hours. After the annealing step is completed, the laser irradiation device 2 is used to separate each steel plate, and a laser beam is linearly scanned in the C direction perpendicular to the L direction. The laser beam is guided by the optical fiber 7, and the laser beam 6 is scan-condensed and irradiated almost perpendicularly to the rolling direction by a scan mirror (not shown) driven by a galvano motor and an fθ lens in the irradiation device 2. Further, the moving device 3 moves in the L direction along the outer shape of the steel sheet, and the entire surface of the steel sheet is irradiated with the laser beam. Here, the L-direction irradiation interval Pl is adjusted by the scan repetition frequency and the moving speed of the irradiation apparatus 2, and a linear or dot-sequence distortion 4 is obtained.
[0010]
In the present invention, the laser beam is a pulse or continuous wave laser, and the condensing shape is a dot or ellipse, and any of the methods provided by the conventional laser distortion introducing method may be used. The iron loss of the grain-oriented electrical steel sheet is reduced by periodic distortion caused by laser irradiation.
In particular, peeling of the surface coating is suppressed by adjusting the temperature reached by the irradiated portion to be equal to or lower than the melting point of the surface coating of the electromagnetic steel sheet by the laser focused beam shape, power density, wavelength, and scanning speed. When formed by such a special method, since the ground iron is not exposed on the surface, there is an advantage that the insulating property is more excellent.
After the laser irradiation, each steel plate is reconfigured into an iron core so as to sandwich the windings in the same order as before separation, and the final winding transformer 5 is manufactured.
[0011]
As another method for producing a wound iron core, there is a method in which one strip-shaped steel plate that is long in the rolling direction is wound into a roll shape, and further formed into a desired square shape, followed by strain relief annealing. After molding by this method, the iron core is unrolled layer by layer and cut at the same time. In the present invention, the steel sheet is irradiated with laser in this unwinding step. As a result, it is possible to continuously irradiate the moving steel sheet with the laser, so that efficient production can be performed. After irradiating and cutting the laser beam, the winding transformer 5 is manufactured by inserting each steel plate into the winding one by one.
[0012]
A winding transformer was manufactured by the manufacturing method described in FIG. The manufacturing conditions are a continuous wave YAG laser output of 50 W and an irradiation pitch Pl = 5 mm. When the performance of a transformer using a wound iron core manufactured under these conditions and a transformer manufactured without laser irradiation were compared, the transformer of the method of the present invention was about 7% more efficient.
Moreover, when this wound iron core was disassembled and the magnetic domain structure of each steel plate was observed with an electron microscope for magnetic domain observation, a circulating magnetic domain was formed in the portion subjected to laser irradiation to give distortion, and the 180 ° domain wall interval was subdivided. It was confirmed that
[0013]
In the present invention, since the magnetic domain control by laser irradiation distortion is performed after the annealing step in the wound iron core manufacturing process and before the final assembly of the winding transformer, the magnetic domain control effect is not lost by annealing, and the iron loss characteristics are reduced. It becomes possible to use an excellent material as a wound iron core material.
[0014]
【The invention's effect】
According to the present invention as described above, a directional electromagnetic wave with improved magnetic characteristics can be used for a wound iron core by forming a circulating magnetic domain by applying laser distortion, and therefore it is possible to provide a wound transformer with excellent magnetic characteristics. It is.
[Brief description of the drawings]
FIG. 1 is a process explanatory diagram of a wound iron core and a manufacturing method thereof according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Directional electrical steel sheet 2 Laser irradiation apparatus 3 Moving apparatus 4 Linear distortion 5 Coiled iron core 6 Laser beam 7 Optical fiber L Rolling direction of directionality electrical steel sheet C Direction of width of directionality electrical steel sheet

Claims (6)

A wound iron core formed by using a grain-oriented electrical steel sheet and subjected to strain relief annealing, and is substantially perpendicular to the rolling direction of the steel sheet on all or part of the surface of the steel sheet constituting the iron core. A wound iron core characterized in that linear or point-strain distortion is imparted at substantially constant intervals in the rolling direction. In the manufacturing method of the wound iron core using the grain-oriented electrical steel sheet, after forming the desired wound-shaped iron core and performing strain relief annealing, all or a part of the surface of the steel sheet constituting the iron core, A method for producing a wound iron core, characterized by imparting linear or point-sequence distortions substantially perpendicular to the rolling direction of a steel sheet at substantially constant intervals in the rolling direction. In the manufacturing method of a wound iron core using a grain-oriented electrical steel sheet, a plurality of steel sheets are overlapped to form a desired wound iron core, and after performing strain relief annealing, all of the steel sheets constituting the iron core, Alternatively, a method for producing a wound iron core, characterized in that a linear or point-sequence distortion substantially perpendicular to the rolling direction of the steel sheet is applied to a part of the surface at substantially constant intervals in the rolling direction. In a method for manufacturing a wound iron core using grain-oriented electrical steel sheets, a single strip steel sheet is formed into a roll shape to form a desired wound iron core, and after performing strain relief annealing, the iron core is wound. A method for producing a wound iron core, characterized in that, in the step of unwinding, linear or point-strain distortion substantially perpendicular to the rolling direction is imparted to the steel sheet surface at substantially constant intervals in the rolling direction. The method for producing a wound iron core according to any one of claims 2 to 4, wherein distortion is imparted by laser irradiation. The manufacture of a wound iron core according to claim 5, wherein an insulating film peeling trace on the steel sheet surface is not generated by adjusting a focused beam shape, power density, laser wavelength, or irradiation speed at the time of laser irradiation. Method.

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